Acute Radiation Syndrome

Complex MONDO:0033938 Pathograph 54 Show in embeddings browser Radiation Injury

Acute radiation syndrome follows whole-body or substantial partial-body exposure to a high dose of penetrating ionizing radiation over a short interval. Injury can involve hematopoietic, gastrointestinal, cutaneous and neurovascular tissues in combination. Dose thresholds do not determine chronological order: early lymphocyte loss and prodromal symptoms can precede marrow failure over subsequent weeks, whereas very-high-dose neurovascular injury can become fatal within days. Dose distribution, radiation quality, concurrent injuries and supportive care influence outcome. Growth factors and a thrombopoietin-receptor agonist target the hematopoietic component; gastrointestinal and other organ injuries require additional supportive care.

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Classifications

Harrison's Part

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Subtypes

Hematopoietic subsyndrome

Marrow injury predominates at lower ARS dose ranges. CDC describes the full syndrome usually between 0.7 and 10 Gy; these are approximate gamma-equivalent ranges and do not exclude concomitant organ injury.

Show evidence (1 reference)

url:https://www.cdc.gov/radiation-emergencies/hcp/clinical-guidance/ars.html SUPPORT DIRECT BACKGROUND Other

"the full syndrome will usually occur with a dose between 0.7 and 10 Gy"

CDC range for the hematopoietic syndrome.

Gastrointestinal subsyndrome

Severe gastrointestinal injury coexists with marrow injury at higher exposures. CDC describes full syndrome usually above approximately 10 Gy, with some symptoms from 6 Gy; other consensus sources use lower syndrome thresholds.

Show evidence (2 references)

url:https://www.cdc.gov/radiation-emergencies/hcp/clinical-guidance/ars.html SUPPORT DIRECT BACKGROUND Other

"the full syndrome will usually occur with a dose greater than approximately 10 Gy"

CDC range for full gastrointestinal syndrome.

url:https://www.cdc.gov/radiation-emergencies/hcp/clinical-guidance/ars.html SUPPORT DIRECT BACKGROUND Other

"Some symptoms may occur as low as 6 Gy or 600 rads."

Lower-dose symptoms do not imply that all cases have a full gastrointestinal syndrome.

Neurovascular subsyndrome

Very-high-dose cardiovascular and central nervous system injury can evolve within hours. CDC describes full syndrome usually above approximately 50 Gy and some symptoms from 20 Gy; these ranges are source-dependent and are not individual survival cutoffs.

Show evidence (2 references)

url:https://www.cdc.gov/radiation-emergencies/hcp/clinical-guidance/ars.html SUPPORT DIRECT BACKGROUND Other

"the full syndrome will usually occur with a dose greater than approximately 50 Gy"

CDC range for full cardiovascular/CNS syndrome.

url:https://www.cdc.gov/radiation-emergencies/hcp/clinical-guidance/ars.html SUPPORT DIRECT BACKGROUND Other

"Some symptoms may occur as low as 20 Gy or 2000 rads."

CDC distinguishes lower-dose symptoms from the full syndrome.

Associated cutaneous radiation injury

Skin injury can accompany systemic ARS or follow localized exposure independently. It is an overlapping organ component, not a mandatory systemic stage.

Show evidence (1 reference)

url:https://www.cdc.gov/radiation-emergencies/hcp/clinical-guidance/ars.html SUPPORT DIRECT BACKGROUND Other

"It is also possible to receive a damaging dose to the skin without symptoms of ARS"

CDC explicitly distinguishes isolated skin irradiation from systemic ARS.

Discussions and Knowledge Gaps

How do exposure heterogeneity, combined injury and available supportive care modify the benefit expected from controlled animal countermeasure studies?

HUMAN MODEL MISMATCH OPEN ars_animal_rule_evidence_base

Attached to

pathophysiology#Bone Marrow Hematopoietic Suppression

Animal efficacy studies support regulatory approval because controlled efficacy experiments involving deliberate harmful human irradiation are unethical or infeasible. Human accident-treatment observations and healthy-volunteer safety/pharmacology studies nevertheless exist. Their designs answer different questions: uncontrolled temporal marrow recovery is not a randomized survival estimate, and healthy-volunteer pharmacology is not irradiated-patient efficacy. Neither the filgrastim macaque experiment nor any single regimen establishes a universal effect for all countermeasures.

Show evidence (3 references)

PMID:21987000 SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical

"Descriptive studies like these that do not have an appropriate, contemporaneous comparison group allow assessment of hypotheses for possible associations but not robust assessments of causality."

Consensus identifies the limitation of uncontrolled accident observations.

url:https://www.accessdata.fda.gov/drugsatfda_docs/label/2021/125268s167lbl.pdf SUPPORT DIRECT BACKGROUND Other

"Approval for this indication was based on efficacy studies conducted in animals"

FDA label identifies the regulatory efficacy source.

clinicaltrials:NCT02343133 SUPPORT DIRECT Human Clinical

"The purpose of this study is to determine whether HemaMax is safe and well tolerated to support efficacy under FDA's Animal Rule to reduce the morbidity and mortality associated with the hematopoietic syndrome of acute radiation syndrome."

Registry description establishes the study purpose and population; it is not an efficacy result.

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Pathophysiology

Radiation-Induced DNA Double-Strand Breaks

Ionizing radiation induces DNA double-strand breaks that activate cellular DNA-damage responses. DNA repair, apoptosis, senescence, and chromosome misrepair are downstream cell-context-dependent outcomes of this proximal lesion.

DNA damage response GO:0006974 ↑ INCREASED

Downstream

Hematopoietic Progenitor Injury DNA damage is upstream of radiation-induced loss of mitotic and survival capacity in marrow stem/progenitor cells.

Radiation-Induced Chromosomal Aberrations Misrepair of DNA double-strand breaks generates dicentric chromosomes and translocations.

Show evidence (2 references)

PMID:24124731 SUPPORT DIRECT REVIEW SYNTHESIS Other

"IR induces several different types of damage to DNA, which include base damages and changes, cross linking, single-strand breaks, and double-strand breaks (DSBs)."

This review places double-strand breaks in the ionizing-radiation DNA-damage response.

PMID:36543843 SUPPORT DIRECT BACKGROUND Other

"Radiation-induced DNA double-strand breaks activate cellular damage repair mechanisms. However, misrepair of chromosomes results in chromosomal aberrations, typically dicentric chromosomes and translocations"

The assay paper describes double-strand breaks as an early molecular lesion after irradiation.

Hematopoietic Progenitor Injury

Radiation impairs survival and proliferative capacity of marrow stem/progenitor cells and their progeny. Radiosensitivity does not mean every hematopoietic stem cell is rapidly cycling. Surviving marrow reserve helps determine reversibility.

hematopoietic stem cell CL:0000037 hematopoietic precursor cell CL:0008001

cellular response to ionizing radiation GO:0071479 ↑ INCREASED

bone marrow UBERON:0002371

Downstream

Bone Marrow Hematopoietic Suppression Loss of functional progenitors reduces hematopoietic capacity.

Show evidence (1 reference)

PMID:21987000 SUPPORT DIRECT REVIEW SYNTHESIS Other

"The primary causes of HS are radiation-induced suppression of mitosis in hematopoietic stem/progenitor cells and their progeny, resulting in hypocellularity and aplasia of the bone marrow and apoptosis in lymphocytes and other hematopoietic cells."

The consensus distinguishes impaired marrow production from radiation-induced lymphocyte apoptosis.

Bone Marrow Hematopoietic Suppression

Reduced marrow cellularity and hematopoietic output follow progenitor injury. Recovery can arise from residual endogenous cells; severe aplasia may persist. Exposure heterogeneity and associated organ injury affect recovery.

bone marrow UBERON:0002371

Animal models

Rhesus macaque filgrastim total-body irradiation study Macaca mulatta recapitulates Reproduces hematopoietic suppression and measures filgrastim-associated survival under this protocol.

Rhesus macaque pegfilgrastim irradiation study Macaca mulatta partially recapitulates Models hematopoietic injury and tests an intervention-associated survival outcome.

Rhesus macaque romiplostim irradiation study Macaca mulatta partially recapitulates Models hematopoietic injury and tests an intervention-associated survival outcome.

Downstream

Multilineage Peripheral Cytopenias Reduced production produces delayed depletion of circulating blood-cell lineages.

Bone marrow hypocellularity Marrow hypocellularity is a tissue manifestation of reduced hematopoiesis.

Show evidence (1 reference)

PMID:21987000 SUPPORT DIRECT REVIEW SYNTHESIS Other

The consensus distinguishes impaired marrow production from radiation-induced lymphocyte apoptosis.

Multilineage Peripheral Cytopenias

Neutropenia, thrombocytopenia and anemia develop with kinetics influenced by lineage turnover, dose and surviving progenitors. Early lymphopenia also reflects direct apoptosis of mature lymphocytes and is represented separately.

Animal models

Rhesus macaque filgrastim total-body irradiation study Macaca mulatta recapitulates Reproduces the peripheral cytopenia phase and measures filgrastim's effect on the duration of neutropenia under this protocol.

Downstream

Decreased total neutrophil count Granulocyte production declines.

Thrombocytopenia Platelet production declines.

Anemia Erythrocyte depletion can follow sustained marrow suppression; it is generally later than neutropenia.

Pancytopenia Multiple blood-cell lineages may be reduced.

Neutropenic Infection Susceptibility Loss of neutrophil defense increases infection risk.

Impaired Primary Hemostasis Thrombocytopenia impairs hemostasis.

Show evidence (1 reference)

PMID:21987000 SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical

"Depending on the dose, dose rate, and radiation quality factor, various degrees of pancytopenia develop over several weeks after whole-body or significant partial-body exposure."

Clinical synthesis supports dose-dependent cytopenias developing over weeks.

Neutropenic Infection Susceptibility

Neutrophil depletion increases susceptibility to infection, including potentially lethal sepsis. This is an acute vulnerability; recurrent infections are not required.

Downstream

Sepsis Infection can progress to systemic illness in the neutropenic host.

Show evidence (1 reference)

url:https://www.fda.gov/emergency-preparedness-and-response/medical-countermeasure-mcm-issues/radiological-and-nuclear-emergency-preparedness SUPPORT DIRECT BACKGROUND Other

"Severe neutropenia increases the risk of sepsis and death due to infections, while thrombocytopenia increases the risk of hemorrhage and death due to bleeding."

FDA describes the distinct infection and bleeding consequences of marrow injury.

Impaired Primary Hemostasis

Reduced circulating platelets increase bleeding risk during hematopoietic radiation injury.

Downstream

Petechiae Thrombocytopenic bleeding may manifest as petechiae.

Show evidence (1 reference)

url:https://www.fda.gov/emergency-preparedness-and-response/medical-countermeasure-mcm-issues/radiological-and-nuclear-emergency-preparedness SUPPORT DIRECT BACKGROUND Other

"Severe neutropenia increases the risk of sepsis and death due to infections, while thrombocytopenia increases the risk of hemorrhage and death due to bleeding."

FDA describes the distinct infection and bleeding consequences of marrow injury.

Mature Lymphocyte Apoptosis

Resting lymphocytes are highly radiosensitive and can undergo early interphase apoptosis. This mechanism contributes to early lymphocyte depletion independently of delayed loss of marrow output.

lymphocyte CL:0000542

apoptotic process GO:0006915 ↑ INCREASED

Experimental models

Irradiated resting human lymphocytes PRIMARY CELL CULTURE Demonstrates early interphase apoptosis in nondividing lymphocytes.

Downstream

Decreased total lymphocyte count Apoptosis contributes to early lymphocyte depletion.

Show evidence (1 reference)

PMID:9525257 SUPPORT DIRECT PRIMARY RESULT In Vitro

"The dose-response data confirm the high radiosensitivity of lymphocytes and demonstrate that their response to undergo early interphase cell death by apoptosis is largely independent of LET."

Resting human lymphocytes underwent apoptosis after ex-vivo irradiation; cell division is not required.

Intestinal Epithelial Injury

Radiation destroys cells of the intestinal epithelial lining, reducing mucosal integrity. Gastrointestinal and marrow injury can coexist.

intestinal epithelial cell CL:0002563

small intestine UBERON:0002108

Downstream

Intestinal Barrier Failure Loss of the epithelial lining disrupts the mucosal barrier.

Show evidence (1 reference)

PMID:21986999 SUPPORT DIRECT REVIEW SYNTHESIS Other

"Destruction of the intestinal epithelial lining causes breakdown of the mucosal barrier that normally separates the contents of the intestinal lumen from the GI tissue, resulting in severe secretory diarrhea, dehydration, and electrolyte imbalance."

Consensus links epithelial destruction to loss of barrier function and gastrointestinal fluid losses.

Intestinal Barrier Failure

Loss of mucosal integrity permits intestinal fluid loss and microbial passage across the bowel wall.

Downstream

Diarrhea Mucosal injury causes secretory diarrhea.

Dehydration Gastrointestinal fluid loss can produce dehydration.

Enteric Bacterial Translocation The damaged mucosal barrier permits enteric bacteria to cross into tissue and blood.

Show evidence (2 references)

PMID:21986999 SUPPORT DIRECT REVIEW SYNTHESIS Other

Consensus links epithelial destruction to loss of barrier function and gastrointestinal fluid losses.

PMID:21986999 SUPPORT DIRECT REVIEW SYNTHESIS Other

"bacterial translocation (passage of bacteria from the intestinal lumen through the defective mucosal barrier and into the bloodstream), which may occur coincident with the period of severe compromise of cell-mediated immunity."

Barrier failure provides a route for enteric organisms to reach the circulation; marrow injury increases vulnerability.

Enteric Bacterial Translocation

Enteric bacteria can cross the radiation-injured mucosa into the circulation, particularly during concomitant immune compromise.

Downstream

Sepsis Translocated bacteria can cause systemic infection.

Show evidence (1 reference)

PMID:21986999 SUPPORT DIRECT REVIEW SYNTHESIS Other

Barrier failure provides a route for enteric organisms to reach the circulation; marrow injury increases vulnerability.

Basal Epidermal Injury

Radiation injury to the basal epidermis impairs skin integrity and produces local inflammation. Skin involvement can evolve after an initially quiet interval.

skin of body UBERON:0002097

Downstream

Erythema Local skin inflammation causes erythema.

Abnormal blistering of the skin Injured skin may blister after the latent interval.

Skin ulcer Severe local injury can cause ulceration.

Show evidence (1 reference)

url:https://www.cdc.gov/radiation-emergencies/hcp/clinical-guidance/ars.html SUPPORT DIRECT BACKGROUND Other

"When the basal cell layer of the skin is damaged by radiation, inflammation, erythema, and dry or moist desquamation can occur."

CDC links basal epidermal injury to local cutaneous manifestations.

Hair Follicle Injury

Radiation can damage hair follicles and cause local epilation; reversibility depends on the extent of injury.

hair follicle UBERON:0002073

Downstream

Alopecia Hair-follicle damage produces epilation.

Show evidence (1 reference)

url:https://www.cdc.gov/radiation-emergencies/hcp/clinical-guidance/ars.html SUPPORT DIRECT BACKGROUND Other

"Also, hair follicles may be damaged, causing epilation."

Hair-follicle injury is a separate cause of post-exposure hair loss.

Neurovascular Injury

At very high exposures, vascular injury, permeability changes and inflammation may contribute to neurovascular collapse. The detailed human mechanism is incompletely resolved. This syndrome can develop faster than delayed marrow failure.

Downstream

Confusion Severe neurovascular injury is associated with this manifestation.

Ataxia Severe neurovascular injury is associated with this manifestation.

Seizure Severe neurovascular injury is associated with this manifestation.

Hypotension Severe neurovascular injury is associated with this manifestation.

Coma Severe neurovascular injury is associated with this manifestation.

Cerebral edema Severe neurovascular injury is associated with this manifestation.

Show evidence (1 reference)

PMID:21986999 SUPPORT INDIRECT REVIEW SYNTHESIS Other

"Several pathophysiologic processes may contribute to neurovascular collapse, including vascular damage, inflammation, cerebral edema, increased vascular permeability, and perivascular hemorrhage."

The consensus presents contributing processes, not a single experimentally resolved human cascade.

Radiation-Induced Chromosomal Aberrations

Misrepair of radiation-induced DNA breaks can generate acquired dicentric chromosomes and other aberrations. The dicentric readout supports biological dosimetry; it is not a germline cause of ARS.

Experimental models

Healthy-donor blood dicentric biodosimetry assay PRIMARY CELL CULTURE Measures acquired dicentrics for calibrated dose estimation.

Show evidence (1 reference)

PMID:36543843 SUPPORT DIRECT BACKGROUND Other

The assay paper explains the biological basis of the acquired chromosome-damage readout.

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Pathograph

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Phenotypes

Blood 7

Decreased total lymphocyte count HP:0001888

Temporal: ACUTE

Show evidence (1 reference)

PMID:21987000 SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical

"The rate of decline in absolute lymphocyte count correlates closely with dose and dose rate, and has been used as a surrogate marker for whole-body dose."

Clinical synthesis supports early lymphocyte depletion as a dose-associated finding.

Decreased total neutrophil count HP:0001875

Temporal: ACUTE

Show evidence (1 reference)

url:https://www.fda.gov/emergency-preparedness-and-response/medical-countermeasure-mcm-issues/radiological-and-nuclear-emergency-preparedness SUPPORT DIRECT BACKGROUND Other

"Severe neutropenia increases the risk of sepsis and death due to infections, while thrombocytopenia increases the risk of hemorrhage and death due to bleeding."

FDA describes the distinct infection and bleeding consequences of marrow injury.

Thrombocytopenia HP:0001873

Temporal: ACUTE

Show evidence (1 reference)

url:https://www.fda.gov/emergency-preparedness-and-response/medical-countermeasure-mcm-issues/radiological-and-nuclear-emergency-preparedness SUPPORT DIRECT BACKGROUND Other

"Severe neutropenia increases the risk of sepsis and death due to infections, while thrombocytopenia increases the risk of hemorrhage and death due to bleeding."

FDA describes the distinct infection and bleeding consequences of marrow injury.

Anemia HP:0001903

Temporal: ACUTE

Show evidence (1 reference)

PMID:21987000 SUPPORT DIRECT REVIEW SYNTHESIS Other

"Individuals with prolonged anemia, a significant decline in hemoglobin concentration, or both may be candidates for treatment with erythropoietin."

The guideline explicitly addresses anemia in radiation-associated marrow injury.

Pancytopenia HP:0001876

Temporal: ACUTE

Show evidence (1 reference)

PMID:21987000 SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical

"Depending on the dose, dose rate, and radiation quality factor, various degrees of pancytopenia develop over several weeks after whole-body or significant partial-body exposure."

Clinical synthesis supports dose-dependent cytopenias developing over weeks.

Bone marrow hypocellularity HP:0005528

Temporal: ACUTE

Show evidence (1 reference)

PMID:21987000 SUPPORT DIRECT REVIEW SYNTHESIS Other

The consensus distinguishes impaired marrow production from radiation-induced lymphocyte apoptosis.

Petechiae HP:0000967

Temporal: ACUTE

Show evidence (1 reference)

PMID:21987000 SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical

"Petechiae, easy bruising, normal hemoglobin level"

The clinical hematopoietic toxicity table includes petechiae.

Cardiovascular 2

Erythema HP:0010783

Temporal: ACUTE

Show evidence (1 reference)

url:https://www.cdc.gov/radiation-emergencies/hcp/clinical-guidance/ars.html SUPPORT DIRECT BACKGROUND Other

"When the basal cell layer of the skin is damaged by radiation, inflammation, erythema, and dry or moist desquamation can occur."

CDC links basal epidermal injury to local cutaneous manifestations.

Hypotension HP:0002615

Temporal: ACUTE

Show evidence (1 reference)

PMID:21986999 SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical

"Disorientation, ataxia, prostration, and seizures, together with fever (>40°C) and hypotension (<80 mm Hg/palpable), are predictive of a nonsurvivable exposure."

Clinical description of severe neurovascular involvement.

Digestive 4

Nausea HP:0002018

Temporal: ACUTE

Show evidence (1 reference)

PMID:21986999 SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical

"Prodromal-phase symptoms include anorexia, nausea, vomiting, and diarrhea."

The clinical review describes gastrointestinal symptoms during the prodrome.

Vomiting HP:0002013

Temporal: ACUTE

Show evidence (1 reference)

PMID:21986999 SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical

"Prodromal-phase symptoms include anorexia, nausea, vomiting, and diarrhea."

The clinical review describes gastrointestinal symptoms during the prodrome.

Anorexia HP:0002039

Temporal: ACUTE

Show evidence (1 reference)

PMID:21986999 SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical

"Prodromal-phase symptoms include anorexia, nausea, vomiting, and diarrhea."

The clinical review describes gastrointestinal symptoms during the prodrome.

Diarrhea HP:0002014

Temporal: ACUTE

Show evidence (2 references)

PMID:21986999 SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical

"Prodromal-phase symptoms include anorexia, nausea, vomiting, and diarrhea."

The clinical review describes gastrointestinal symptoms during the prodrome.

PMID:21986999 SUPPORT DIRECT REVIEW SYNTHESIS Other

Consensus links epithelial destruction to loss of barrier function and gastrointestinal fluid losses.

Head and Neck 1

Stomatitis HP:0010280

Temporal: ACUTE

Show evidence (1 reference)

url:https://www.cdc.gov/radiation-emergencies/hcp/clinical-guidance/ars.html SUPPORT DIRECT BACKGROUND Other

"Careful observation for erythema (document locations), hair loss, skin injury, mucositis, parotitis, weight loss, or fever"

CDC includes mucositis among findings to watch for during ARS management; HPO represents oral mucositis through Stomatitis.

Immune 1

Sepsis HP:0100806

Temporal: ACUTE

Show evidence (1 reference)

url:https://www.fda.gov/emergency-preparedness-and-response/medical-countermeasure-mcm-issues/radiological-and-nuclear-emergency-preparedness SUPPORT DIRECT BACKGROUND Other

"Severe neutropenia increases the risk of sepsis and death due to infections, while thrombocytopenia increases the risk of hemorrhage and death due to bleeding."

FDA describes the distinct infection and bleeding consequences of marrow injury.

Integument 3

Abnormal blistering of the skin HP:0008066

Temporal: ACUTE

Show evidence (1 reference)

url:https://www.cdc.gov/radiation-emergencies/hcp/clinical-guidance/ars.html SUPPORT DIRECT BACKGROUND Other

"when intense reddening, blistering, and ulceration of the irradiated site are visible."

Clinical guidance lists blistering after latent skin injury.

Skin ulcer HP:0200042

Temporal: ACUTE

Show evidence (1 reference)

url:https://www.cdc.gov/radiation-emergencies/hcp/clinical-guidance/ars.html SUPPORT DIRECT BACKGROUND Other

"when intense reddening, blistering, and ulceration of the irradiated site are visible."

Clinical guidance lists skin ulceration.

Alopecia HP:0001596

Temporal: ACUTE

Show evidence (1 reference)

url:https://www.cdc.gov/radiation-emergencies/hcp/clinical-guidance/ars.html SUPPORT DIRECT BACKGROUND Other

"Also, hair follicles may be damaged, causing epilation."

Hair-follicle injury is a separate cause of post-exposure hair loss.

Metabolism 3

Dehydration HP:0001944

Temporal: ACUTE

Show evidence (1 reference)

PMID:21986999 SUPPORT DIRECT REVIEW SYNTHESIS Other

Consensus links epithelial destruction to loss of barrier function and gastrointestinal fluid losses.

Fever HP:0001945

Temporal: ACUTE

Show evidence (1 reference)

PMID:21986999 SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical

"Disorientation, ataxia, prostration, and seizures, together with fever (>40°C) and hypotension (<80 mm Hg/palpable), are predictive of a nonsurvivable exposure."

Clinical description of severe neurovascular involvement.

Cerebral edema HP:0002181

Temporal: ACUTE

Show evidence (1 reference)

PMID:21986999 SUPPORT INDIRECT REVIEW SYNTHESIS Other

"Several pathophysiologic processes may contribute to neurovascular collapse, including vascular damage, inflammation, cerebral edema, increased vascular permeability, and perivascular hemorrhage."

The consensus presents contributing processes, not a single experimentally resolved human cascade.

Nervous System 4

Confusion HP:0001289

Temporal: ACUTE

Show evidence (1 reference)

PMID:21986999 SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical

"Disorientation, ataxia, prostration, and seizures, together with fever (>40°C) and hypotension (<80 mm Hg/palpable), are predictive of a nonsurvivable exposure."

Clinical description of severe neurovascular involvement.

Ataxia HP:0001251

Temporal: ACUTE

Show evidence (1 reference)

PMID:21986999 SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical

"Disorientation, ataxia, prostration, and seizures, together with fever (>40°C) and hypotension (<80 mm Hg/palpable), are predictive of a nonsurvivable exposure."

Clinical description of severe neurovascular involvement.

Seizure HP:0001250

Temporal: ACUTE

Show evidence (1 reference)

PMID:21986999 SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical

"Disorientation, ataxia, prostration, and seizures, together with fever (>40°C) and hypotension (<80 mm Hg/palpable), are predictive of a nonsurvivable exposure."

Clinical description of severe neurovascular involvement.

Coma HP:0001259

Temporal: ACUTE

Show evidence (1 reference)

PMID:21986999 SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical

"A brief latent period lasting several hours typically is followed by severe incapacitation, progressing to coma and death within 24 to 48 hours."

Very-high-dose neurovascular illness can progress rapidly after a short latent interval.

Constitutional 1

Malaise HP:0033834

Temporal: ACUTE

Show evidence (1 reference)

url:https://www.cdc.gov/radiation-emergencies/hcp/clinical-guidance/ars.html SUPPORT DIRECT BACKGROUND Other

"Symptoms are anorexia, fever, and malaise."

CDC lists malaise during manifest hematopoietic radiation illness.

Growth 1

Weight loss HP:0001824

Temporal: ACUTE

Show evidence (1 reference)

url:https://www.cdc.gov/radiation-emergencies/hcp/clinical-guidance/ars.html SUPPORT DIRECT BACKGROUND Other

"Careful observation for erythema (document locations), hair loss, skin injury, mucositis, parotitis, weight loss, or fever"

CDC includes weight loss among findings to watch for during ARS management.

💊

Medical Actions

Filgrastim

Action: Pharmacotherapy NCIT:C15986

Agent: Filgrastim NCIT:C1474

Platform: Other

Recombinant G-CSF is FDA-approved to improve survival after myelosuppressive radiation exposure. It stimulates residual hematopoiesis. The cited macaque experiment shortened neutropenia without changing its nadir and demonstrated a protocol-specific survival benefit.

Mechanism Target:

RESTORES Bone Marrow Hematopoietic Suppression — Stimulates recovery of granulopoiesis from surviving progenitors.

Show evidence (3 references)

PMID:23210705 SUPPORT DIRECT PRIMARY RESULT Model Organism

"Filgrastim significantly (P < 0.004) reduced 60 day overall mortality [20.8% (5/24)] compared to the controls [59.1% (13/22)]."

Randomized rhesus study with supportive care: mortality difference was 38.3 percentage points under this protocol.

PMID:23210705 SUPPORT DIRECT PRIMARY RESULT Model Organism

"Filgrastim significantly decreased the duration of neutropenia, but did not affect the absolute neutrophil count nadir."

The duration-versus-nadir result applies to this regimen and does not define every countermeasure.

url:https://www.fda.gov/emergency-preparedness-and-response/medical-countermeasure-mcm-issues/radiological-and-nuclear-emergency-preparedness SUPPORT DIRECT BACKGROUND Other

"Neupogen (filgrastim) – approved March 2015"

FDA current preparedness page lists the approved parent product; biosimilars are not separate mechanisms.

Show evidence (3 references)

PMID:23210705 SUPPORT DIRECT PRIMARY RESULT Model Organism

"Filgrastim significantly (P < 0.004) reduced 60 day overall mortality [20.8% (5/24)] compared to the controls [59.1% (13/22)]."

Randomized rhesus study with supportive care: mortality difference was 38.3 percentage points under this protocol.

PMID:23210705 SUPPORT DIRECT PRIMARY RESULT Model Organism

"Filgrastim significantly decreased the duration of neutropenia, but did not affect the absolute neutrophil count nadir."

The duration-versus-nadir result applies to this regimen and does not define every countermeasure.

url:https://www.fda.gov/emergency-preparedness-and-response/medical-countermeasure-mcm-issues/radiological-and-nuclear-emergency-preparedness SUPPORT DIRECT BACKGROUND Other

"Neupogen (filgrastim) – approved March 2015"

FDA current preparedness page lists the approved parent product; biosimilars are not separate mechanisms.

Pegfilgrastim

Action: Pharmacotherapy NCIT:C15986

Agent: Pegfilgrastim NCIT:C1854

Platform: Other

Pegylated G-CSF is another FDA-approved hematopoietic countermeasure. Its animal efficacy study used a separate two-dose regimen and does not establish a gastrointestinal or neurovascular treatment effect.

Mechanism Target:

RESTORES Bone Marrow Hematopoietic Suppression — Promotes recovery of hematopoietic cell production.

Show evidence (3 references)

url:https://www.accessdata.fda.gov/drugsatfda_docs/label/2015/125031s180lbl.pdf SUPPORT DIRECT BACKGROUND Other

"Pegfilgrastim is a colony-stimulating factor that acts on hematopoietic cells by binding to specific cell surface receptors, thereby stimulating proliferation, differentiation, commitment, and end cell functional activation."

FDA label explains colony-stimulating activity.

url:https://www.fda.gov/emergency-preparedness-and-response/medical-countermeasure-mcm-issues/radiological-and-nuclear-emergency-preparedness SUPPORT DIRECT BACKGROUND Other

"Neulasta (pegfilgrastim) – approved November 2015"

FDA current preparedness page lists the approved parent product; biosimilars are not separate mechanisms.

url:https://www.accessdata.fda.gov/drugsatfda_docs/label/2015/125031s180lbl.pdf SUPPORT DIRECT REVIEW SYNTHESIS Model Organism

"91% survival (21/23) in the pegfilgrastim group compared to 48% survival (11/23) in the control group."

This separate randomized rhesus study used treatment on days 1 and 8 plus medical management; it is not the filgrastim trial.

Show evidence (3 references)

url:https://www.accessdata.fda.gov/drugsatfda_docs/label/2015/125031s180lbl.pdf SUPPORT DIRECT BACKGROUND Other

FDA label explains colony-stimulating activity.

url:https://www.fda.gov/emergency-preparedness-and-response/medical-countermeasure-mcm-issues/radiological-and-nuclear-emergency-preparedness SUPPORT DIRECT BACKGROUND Other

"Neulasta (pegfilgrastim) – approved November 2015"

FDA current preparedness page lists the approved parent product; biosimilars are not separate mechanisms.

url:https://www.accessdata.fda.gov/drugsatfda_docs/label/2015/125031s180lbl.pdf SUPPORT DIRECT REVIEW SYNTHESIS Model Organism

"91% survival (21/23) in the pegfilgrastim group compared to 48% survival (11/23) in the control group."

This separate randomized rhesus study used treatment on days 1 and 8 plus medical management; it is not the filgrastim trial.

Sargramostim

Action: Pharmacotherapy NCIT:C15986

Agent: Sargramostim NCIT:C1492

Platform: Other

Recombinant GM-CSF is FDA-approved for hematopoietic ARS and stimulates surviving myeloid progenitors. Human accident reports of colony-stimulating factors are uncontrolled and do not supply a precise drug-specific survival effect.

Mechanism Target:

RESTORES Bone Marrow Hematopoietic Suppression — Stimulates recovery of myeloid hematopoiesis.

Show evidence (2 references)

PMID:34402734 SUPPORT DIRECT REVIEW SYNTHESIS Other

"These agents are largely recombinant growth factors (e.g. rhuG-CSF/filgrastim, rhuGM-CSF/sargramostim) that target and stimulate myeloid progenitors within bone marrow."

Review identifies sargramostim and its marrow progenitor target.

url:https://www.fda.gov/emergency-preparedness-and-response/medical-countermeasure-mcm-issues/radiological-and-nuclear-emergency-preparedness SUPPORT DIRECT BACKGROUND Other

"Leukine (sargramostim) – approved March 29, 2018"

FDA current preparedness page lists the approved parent product; biosimilars are not separate mechanisms.

Show evidence (2 references)

PMID:34402734 SUPPORT DIRECT REVIEW SYNTHESIS Other

"These agents are largely recombinant growth factors (e.g. rhuG-CSF/filgrastim, rhuGM-CSF/sargramostim) that target and stimulate myeloid progenitors within bone marrow."

Review identifies sargramostim and its marrow progenitor target.

url:https://www.fda.gov/emergency-preparedness-and-response/medical-countermeasure-mcm-issues/radiological-and-nuclear-emergency-preparedness SUPPORT DIRECT BACKGROUND Other

"Leukine (sargramostim) – approved March 29, 2018"

FDA current preparedness page lists the approved parent product; biosimilars are not separate mechanisms.

Romiplostim

Action: Pharmacotherapy NCIT:C15986

Agent: Romiplostim NCIT:C52183

Platform: Other

The FDA-approved thrombopoietin-receptor agonist is an Fc-peptide fusion protein that increases platelet production. Regulatory efficacy rests on animal studies, with supportive human pharmacodynamic and safety information from other settings.

Mechanism Target:

INHIBITS Thrombocytopenia — Increases platelet production through activation of the TPO receptor.

Show evidence (4 references)

url:https://www.accessdata.fda.gov/drugsatfda_docs/label/2021/125268s167lbl.pdf SUPPORT DIRECT BACKGROUND Other

"Romiplostim is a thrombopoietin receptor agonist (TPO-RA). Romiplostim, a member of the TPO mimetic class, is an Fc-peptide fusion protein (peptibody)."

Romiplostim is a biologic peptibody, not a small molecule.

url:https://www.accessdata.fda.gov/drugsatfda_docs/label/2021/125268s167lbl.pdf SUPPORT DIRECT BACKGROUND Other

"Nplate increases platelet production through binding and activation of the TPO receptor, a mechanism analogous to endogenous TPO."

FDA label supports the platelet-production mechanism.

url:https://www.accessdata.fda.gov/drugsatfda_docs/label/2021/125268s167lbl.pdf SUPPORT DIRECT BACKGROUND Other

"Nplate is indicated to increase survival in adults and in pediatric patients (including term neonates) acutely exposed to myelosuppressive doses of radiation"

FDA label states the hematopoietic ARS indication.

+ 1 more reference

Show evidence (4 references)

url:https://www.accessdata.fda.gov/drugsatfda_docs/label/2021/125268s167lbl.pdf SUPPORT DIRECT BACKGROUND Other

"Romiplostim is a thrombopoietin receptor agonist (TPO-RA). Romiplostim, a member of the TPO mimetic class, is an Fc-peptide fusion protein (peptibody)."

Romiplostim is a biologic peptibody, not a small molecule.

url:https://www.accessdata.fda.gov/drugsatfda_docs/label/2021/125268s167lbl.pdf SUPPORT DIRECT BACKGROUND Other

"Nplate increases platelet production through binding and activation of the TPO receptor, a mechanism analogous to endogenous TPO."

FDA label supports the platelet-production mechanism.

url:https://www.accessdata.fda.gov/drugsatfda_docs/label/2021/125268s167lbl.pdf SUPPORT DIRECT BACKGROUND Other

"Nplate is indicated to increase survival in adults and in pediatric patients (including term neonates) acutely exposed to myelosuppressive doses of radiation"

FDA label states the hematopoietic ARS indication.

+ 1 more reference

Erythropoiesis-stimulating agents for prolonged anemia

Action: Pharmacotherapy NCIT:C15986

Agent: Recombinant Erythropoietin NCIT:C477

Platform: Other

The 2011 consensus weakly recommends considering erythropoietin in selected patients with prolonged anemia or a significant hemoglobin decline. Response takes weeks. Use requires individualized assessment of risks, iron status and applicable product labeling; this recommendation does not establish controlled human ARS efficacy or an FDA ARS indication.

Mechanism Target:

INHIBITS Anemia — Stimulates erythrocyte production in selected patients with prolonged anemia.

Show evidence (3 references)

PMID:21987000 SUPPORT DIRECT REVIEW SYNTHESIS Other

"Individuals with prolonged anemia, a significant decline in hemoglobin concentration, or both may be candidates for treatment with erythropoietin."

The 2011 consensus makes a weak recommendation for selected prolonged anemia; this is not controlled human ARS efficacy.

PMID:21987000 SUPPORT DIRECT REVIEW SYNTHESIS Other

"Experiencing a response to erythropoietin will take weeks rather than days."

The expected response is delayed and does not replace urgent transfusion support.

PMID:21987000 SUPPORT DIRECT REVIEW SYNTHESIS Other

"Strong caveats recommending specific indications for the use of ESAs are incorporated in a “black box” warning by the US Food and Drug Administration (FDA)."

The consensus emphasizes regulatory safety constraints and individualized selection.

Show evidence (3 references)

PMID:21987000 SUPPORT DIRECT REVIEW SYNTHESIS Other

"Individuals with prolonged anemia, a significant decline in hemoglobin concentration, or both may be candidates for treatment with erythropoietin."

The 2011 consensus makes a weak recommendation for selected prolonged anemia; this is not controlled human ARS efficacy.

PMID:21987000 SUPPORT DIRECT REVIEW SYNTHESIS Other

"Experiencing a response to erythropoietin will take weeks rather than days."

The expected response is delayed and does not replace urgent transfusion support.

PMID:21987000 SUPPORT DIRECT REVIEW SYNTHESIS Other

"Strong caveats recommending specific indications for the use of ESAs are incorporated in a “black box” warning by the US Food and Drug Administration (FDA)."

The consensus emphasizes regulatory safety constraints and individualized selection.

Antimicrobial prophylaxis and infection treatment

Action: Antibiotic Therapy NCIT:C15620

Infection prevention and prompt treatment are central during neutropenia. Antibacterial, antifungal and antiviral choices depend on clinical findings, cultures, local resistance and patient factors; the evidence for specific gastrointestinal prophylaxis strategies is limited.

Mechanism Target:

INHIBITS Sepsis — Antimicrobial treatment addresses infection complicating immune and barrier injury.

Show evidence (1 reference)

PMID:21986999 SUPPORT DIRECT REVIEW SYNTHESIS Other

"Patients with suspected or established infection should be placed on a treatment regimen that is similar to that of patients with malignancy and neutropenic sepsis."

Consensus supports management of neutropenic infection.

Show evidence (1 reference)

PMID:21986999 SUPPORT DIRECT REVIEW SYNTHESIS Other

"Patients with suspected or established infection should be placed on a treatment regimen that is similar to that of patients with malignancy and neutropenic sepsis."

Consensus supports management of neutropenic infection.

Fluid and electrolyte replacement

Action: Fluid Therapy NCIT:C116537

Replace losses from vomiting and diarrhea and support intravascular volume according to clinical and laboratory assessment.

Mechanism Target:

INHIBITS Dehydration — Replenishes lost fluid and electrolytes.

Show evidence (1 reference)

PMID:21986999 SUPPORT DIRECT REVIEW SYNTHESIS Other

"Hospitalized patients should be provided with electrolyte and fluid replacement."

Consensus recommends fluid/electrolyte support.

Show evidence (1 reference)

PMID:21986999 SUPPORT DIRECT REVIEW SYNTHESIS Other

"Hospitalized patients should be provided with electrolyte and fluid replacement."

Consensus recommends fluid/electrolyte support.

Antiemetic therapy

Action: Nausea and Vomiting Therapy NCIT:C15473

Serotonin-receptor antagonists are recommended for radiation-associated nausea and vomiting. This is symptom control, not reversal of the initial radiation injury.

Mechanism Target:

INHIBITS Vomiting — Reduces emesis and associated fluid loss.

Show evidence (1 reference)

PMID:21986999 SUPPORT DIRECT REVIEW SYNTHESIS Other

"The antiemetic of choice is a serotonin-receptor antagonist"

Consensus identifies this class as preferred antiemetic support.

Show evidence (1 reference)

PMID:21986999 SUPPORT DIRECT REVIEW SYNTHESIS Other

"The antiemetic of choice is a serotonin-receptor antagonist"

Consensus identifies this class as preferred antiemetic support.

Antidiarrheal therapy

Action: Pharmacotherapy NCIT:C15986

Agent: loperamide CHEBI:6532

Loperamide is a recommended symptomatic option for diarrhea. The consensus recommendation is weak and does not establish reversal of mucosal injury.

Mechanism Target:

INHIBITS Diarrhea — Reduces the diarrheal symptom burden.

Show evidence (1 reference)

PMID:21986999 SUPPORT DIRECT REVIEW SYNTHESIS Other

"Administer loperamide pro re nata for control of diarrhea"

Consensus table recommends symptomatic diarrhea control.

Show evidence (1 reference)

PMID:21986999 SUPPORT DIRECT REVIEW SYNTHESIS Other

"Administer loperamide pro re nata for control of diarrhea"

Consensus table recommends symptomatic diarrhea control.

Nutritional support

Action: Nutritional Support NCIT:C15433

Enteral support is preferred when feasible; parenteral support may be required when ileus or diffuse gastrointestinal mucosal bleeding prevents its use.

Show evidence (2 references)

PMID:21986999 SUPPORT DIRECT REVIEW SYNTHESIS Other

"parenteral support is indicated in patients with adynamic ileus or diffuse bleeding from the GI mucosa."

The full consensus text supplies the exception to enteral support.

PMID:21986999 SUPPORT DIRECT REVIEW SYNTHESIS Other

"Oral nutritional support is preferred over parenteral nutrition because it promotes the immunological and physiological integrity of the GI tract"

Consensus supports enteral nutrition when feasible.

Transfusion support

Action: Platelet Transfusion NCIT:C15366

Platelet transfusion may be required for severe thrombocytopenia. Blood-product support is supportive treatment and does not demonstrate restored endogenous marrow production.

Mechanism Target:

BYPASSES Thrombocytopenia — Supplies platelets while endogenous production is impaired.

Show evidence (1 reference)

url:https://www.cdc.gov/radiation-emergencies/hcp/clinical-guidance/ars.html SUPPORT DIRECT REVIEW SYNTHESIS Other

"Stem cell transplantation or platelet transfusions (if platelet count is too low)"

CDC lists platelet transfusion among indicated support measures.

Show evidence (1 reference)

url:https://www.cdc.gov/radiation-emergencies/hcp/clinical-guidance/ars.html SUPPORT DIRECT REVIEW SYNTHESIS Other

"Stem cell transplantation or platelet transfusions (if platelet count is too low)"

CDC lists platelet transfusion among indicated support measures.

Selective hematopoietic stem-cell transplantation

Action: Hematopoietic Cell Transplantation NCIT:C15431

Consider transplantation only for persistent marrow aplasia without spontaneous recovery or response after 2–3 weeks of cytokine treatment and without significant nonhematopoietic organ injury. The consensus recommendation is weak; historical uncontrolled outcomes do not establish benefit from routine early transplantation.

Mechanism Target:

RESTORES Bone Marrow Hematopoietic Suppression — Provides hematopoietic progenitors in selected patients with persistent marrow failure.

Show evidence (2 references)

PMID:21987000 SUPPORT DIRECT REVIEW SYNTHESIS Other

"Stem/progenitor cell replacement therapy should not be administered until there is a documented lack of spontaneous recovery and/or lack of response following 2 to 3 weeks of cytokine treatment."

Consensus restricts timing and patient selection.

PMID:21987000 SUPPORT DIRECT REVIEW SYNTHESIS Other

"it has been recommended that hematopoietic stem/progenitor cell therapy not be used for patients with aplasia and significant injury to another organ system."

Nonhematopoietic organ injury limits transplantation candidacy.

Show evidence (2 references)

PMID:21987000 SUPPORT DIRECT REVIEW SYNTHESIS Other

"Stem/progenitor cell replacement therapy should not be administered until there is a documented lack of spontaneous recovery and/or lack of response following 2 to 3 weeks of cytokine treatment."

Consensus restricts timing and patient selection.

PMID:21987000 SUPPORT DIRECT REVIEW SYNTHESIS Other

"it has been recommended that hematopoietic stem/progenitor cell therapy not be used for patients with aplasia and significant injury to another organ system."

Nonhematopoietic organ injury limits transplantation candidacy.

Topical treatment of cutaneous radiation injury

Action: Wound Care Management NCIT:C116681

Specialist local care can include topical corticosteroids, antibiotics and antihistamines. Systemic corticosteroids are not routine therapy without a specific indication.

Mechanism Target:

INHIBITS Erythema — Topical anti-inflammatory care reduces cutaneous inflammation.

Show evidence (1 reference)

PMID:21986999 SUPPORT DIRECT REVIEW SYNTHESIS Other

"Anti-inflammatory agents such as topical class II to III steroids (eg, betamethasone, mometasone), topical antibiotics, and antihistamines should be considered."

Consensus describes topical management of radiation skin injury.

Show evidence (1 reference)

PMID:21986999 SUPPORT DIRECT REVIEW SYNTHESIS Other

"Anti-inflammatory agents such as topical class II to III steroids (eg, betamethasone, mometasone), topical antibiotics, and antihistamines should be considered."

Consensus describes topical management of radiation skin injury.

Excision and grafting for severe skin injury

Action: Skin Transplantation NCIT:C15325

Surgical excision and grafting may be required for radiation ulcers, localized necrosis or severe intractable pain, with specialist assessment of injury extent.

Mechanism Target:

BYPASSES Skin ulcer — Resects severely injured tissue and replaces lost skin coverage.

Show evidence (1 reference)

PMID:21986999 SUPPORT DIRECT REVIEW SYNTHESIS Other

"Ulcers, localized necrosis, and severe intractable pain are best treated by surgical excision and skin grafts."

Consensus specifies circumstances for surgery.

Show evidence (1 reference)

PMID:21986999 SUPPORT DIRECT REVIEW SYNTHESIS Other

"Ulcers, localized necrosis, and severe intractable pain are best treated by surgical excision and skin grafts."

Consensus specifies circumstances for surgery.

Neurovascular supportive and palliative care

Action: Palliative Therapy NCIT:C15292

Provide symptom relief, seizure management and appropriate supportive or palliative care for severe neurovascular syndrome. Such care does not imply established reversal of nonsurvivable radiation injury.

Show evidence (1 reference)

PMID:21986999 SUPPORT DIRECT REVIEW SYNTHESIS Other

"At present, supportive care alone is recommended for patients diagnosed as having the neurovascular syndrome."

Consensus emphasizes supportive care rather than proven organ rescue.

Intensive care organ support

Action: Supportive Care NCIT:C15747

Severe multisystem injury may require intensive care, including lung-protective mechanical ventilation for acute respiratory failure and individualized hemodynamic or renal support. These are supportive-care recommendations extrapolated in part from other critical illnesses, not demonstrated reversal of radiation damage.

Show evidence (2 references)

PMID:21986999 SUPPORT DIRECT REVIEW SYNTHESIS Other

"Administer mechanical ventilation with a lung-protective strategy for acute respiratory failure"

The consensus table gives a strong recommendation for supportive ventilation.

PMID:21986999 SUPPORT DIRECT REVIEW SYNTHESIS Other

"hemodialysis for patients with significant renal impairment."

The 2011 consensus identifies renal replacement as possible supportive care; no ARS-specific efficacy estimate is supplied.

Psychological support

Action: Supportive Care NCIT:C15747

Provide psychological support for exposed patients and families alongside physical care.

Show evidence (1 reference)

PMID:21986999 SUPPORT DIRECT REVIEW SYNTHESIS Other

"every attempt should be made to provide psychological support, sedatives, and anxiolytics, as necessary."

Consensus includes psychological support alongside medical management.

HemaMax (investigational recombinant human IL-12)

Action: Pharmacotherapy NCIT:C15986

Agent: recombinant human interleukin-12 (HemaMax)

Platform: Other

HemaMax has completed registered Phase I and Phase II healthy-volunteer safety/pharmacology studies for countermeasure development. These studies do not establish efficacy against ARS in irradiated people.

Show evidence (2 references)

clinicaltrials:NCT01742221 SUPPORT DIRECT Human Clinical

"This trial is designed to evaluate the safety, pharmacokinetics, and pharmacodynamics of HemaMax in healthy male and female volunteers."

Registry description establishes the study purpose and population; it is not an efficacy result.

clinicaltrials:NCT02343133 SUPPORT DIRECT Human Clinical

Registry description establishes the study purpose and population; it is not an efficacy result.

🌍

Environmental Factors

Acute whole-body or substantial partial-body ionizing radiation exposure

Hazard type: PHYSICAL

Duration: ACUTE

The ECTO binding covers ionizing-radiation exposure broadly; the acute duration, penetrating quality and extent are specified in this record. Localized skin injury alone does not establish systemic ARS.

A large short-duration dose of penetrating radiation to the whole body or a substantial fraction can produce ARS. Dose distribution can be heterogeneous. Irradiation is distinct from radioactive contamination, which may coexist; chemical absorption-route categories do not describe external irradiation.

Show evidence (1 reference)

url:https://www.cdc.gov/radiation-emergencies/hcp/clinical-guidance/ars.html SUPPORT DIRECT BACKGROUND Other

"Acute Radiation Syndrome (ARS) (sometimes known as acute radiation sickness) is an acute illness caused by radiation exposure (or irradiation) of the entire body (or most of the body) by a high dose of penetrating radiation in a very short period of time (usually a matter of minutes)."

Clinical guidance defines the systemic exposure pattern.

Mechanism Target:

TRIGGERS Radiation-Induced DNA Double-Strand Breaks — Radiation exposure induces the DNA double-strand-break response.

Show evidence (1 reference)

PMID:24124731 SUPPORT DIRECT REVIEW SYNTHESIS Other

"IR induces several different types of damage to DNA, which include base damages and changes, cross linking, single-strand breaks, and double-strand breaks (DSBs)."

This review describes ionizing radiation as an inducer of DNA double-strand breaks.

TRIGGERS Mature Lymphocyte Apoptosis — Radiation exposure initiates this component of tissue injury.

Show evidence (1 reference)

PMID:9525257 SUPPORT DIRECT PRIMARY RESULT In Vitro

"The dose-response data confirm the high radiosensitivity of lymphocytes and demonstrate that their response to undergo early interphase cell death by apoptosis is largely independent of LET."

Resting human lymphocytes underwent apoptosis after ex-vivo irradiation; cell division is not required.

TRIGGERS Intestinal Epithelial Injury — Radiation exposure initiates this component of tissue injury.

Show evidence (1 reference)

PMID:21986999 SUPPORT DIRECT REVIEW SYNTHESIS Other

Consensus links epithelial destruction to loss of barrier function and gastrointestinal fluid losses.

TRIGGERS Basal Epidermal Injury — Radiation exposure initiates this component of tissue injury.

Show evidence (1 reference)

url:https://www.cdc.gov/radiation-emergencies/hcp/clinical-guidance/ars.html SUPPORT DIRECT BACKGROUND Other

"When the basal cell layer of the skin is damaged by radiation, inflammation, erythema, and dry or moist desquamation can occur."

CDC links basal epidermal injury to local cutaneous manifestations.

TRIGGERS Hair Follicle Injury — Radiation exposure initiates this component of tissue injury.

Show evidence (1 reference)

url:https://www.cdc.gov/radiation-emergencies/hcp/clinical-guidance/ars.html SUPPORT DIRECT BACKGROUND Other

"Also, hair follicles may be damaged, causing epilation."

Hair-follicle injury is a separate cause of post-exposure hair loss.

TRIGGERS Neurovascular Injury — Radiation exposure initiates this component of tissue injury.

Show evidence (1 reference)

PMID:21986999 SUPPORT INDIRECT REVIEW SYNTHESIS Other

"Several pathophysiologic processes may contribute to neurovascular collapse, including vascular damage, inflammation, cerebral edema, increased vascular permeability, and perivascular hemorrhage."

The consensus presents contributing processes, not a single experimentally resolved human cascade.

🔬

Diagnosis

Dicentric chromosome assay biodosimetry

Dicentric chromosomes in cultured peripheral lymphocytes are scored against a calibrated dose-response curve. This is a reference method for biological dose estimation, with laboratory and throughput constraints. Automated scoring remains method-dependent; the cited DLADES evaluation used healthy donor blood irradiated ex vivo, not an ARS casualty cohort.

Show evidence (2 references)

PMID:36543843 SUPPORT Other

"The dicentric chromosome assay is the "gold standard" in biodosimetry for estimating radiation exposure."

Establishes the assay as the reference standard for dose estimation.

PMID:36543843 SUPPORT Other

"its large-scale deployment is limited owing to its time-consuming nature and requirement for expert reviewers"

Records the throughput limitation, which is what makes the faster clinical triage methods below necessary rather than merely convenient.

Lymphocyte depletion kinetics and time to emesis

Serial lymphocyte counts and the interval from exposure to vomiting support early dose assessment. They should be interpreted with exposure history, physical dosimetry, cytogenetics and evolving clinical findings. Vomiting can be absent after a clinically important exposure or occur for other reasons; a single count or symptom should not determine prognosis.

Show evidence (4 references)

PMID:17993851 SUPPORT Human Clinical

"Lymphocyte depletion kinetics and time to emesis have previously been shown to correlate with radiation dose."

Establishes both triage parameters as dose-correlated.

PMID:17993851 SUPPORT Human Clinical

"dose can be estimated by a simple table lookup, given the ratio of two lymphocyte counts and the time between blood samples."

Documents the simplified method, derived from radiation-accident case data, that makes lymphocyte kinetics usable at the bedside.

PMID:21986999 SUPPORT DIRECT REVIEW SYNTHESIS Other

"Health care providers should base individualized treatment decisions on whatever data are available, especially clinical signs and symptoms, but also take into consideration physical dosimetry and individual biodosimetry."

Consensus recommends integrated assessment rather than a symptom-only dose estimate.

+ 1 more reference

Serial assessment of organ involvement

Assess blood-cell lineages and gastrointestinal, cutaneous and neurologic findings over time, including areas and timing of skin injury. Apparent wellness during a latent interval does not exclude evolving organ damage.

Show evidence (2 references)

url:https://www.cdc.gov/radiation-emergencies/hcp/clinical-guidance/ars.html SUPPORT DIRECT BACKGROUND Other

"In this stage, the patient looks and feels generally healthy for a few hours or even up to a few weeks."

CDC describes the latent stage.

url:https://www.cdc.gov/radiation-emergencies/hcp/clinical-guidance/ars.html SUPPORT DIRECT BACKGROUND Other

"Precisely record all clinical symptoms, particularly nausea, vomiting, diarrhea, and itching, reddening or blistering of the skin. Be sure to include time of onset."

Clinical guidance supports serial symptom and skin documentation.

🪜

Stages

Prodromal stage

Nausea, vomiting, anorexia and sometimes diarrhea can begin within minutes to days; timing and severity depend on exposure.

Show evidence (1 reference)

url:https://www.cdc.gov/radiation-emergencies/hcp/clinical-guidance/ars.html SUPPORT DIRECT BACKGROUND Other

"The classic symptoms for this stage are nausea, vomiting, as well as anorexia and possibly diarrhea (depending on dose)"

CDC describes the prodromal symptom cluster.

Latent stage

Symptoms may improve while tissue injury continues. Its duration varies greatly and can be very brief after severe exposure.

Show evidence (1 reference)

url:https://www.cdc.gov/radiation-emergencies/hcp/clinical-guidance/ars.html SUPPORT DIRECT BACKGROUND Other

"In this stage, the patient looks and feels generally healthy for a few hours or even up to a few weeks."

The latent interval does not demonstrate recovery.

Manifest illness stage

Organ-specific hematologic, gastrointestinal, skin or neurovascular manifestations emerge; subsyndromes can coexist.

Show evidence (1 reference)

url:https://www.cdc.gov/radiation-emergencies/hcp/clinical-guidance/ars.html SUPPORT DIRECT BACKGROUND Other

"In this stage the symptoms depend on the specific syndrome"

CDC describes the organ-dependent manifest phase.

Recovery or death

Outcome depends on exposure, residual tissue reserve, associated injury and care. Recovery can take weeks to years; neurovascular death can occur within days.

Show evidence (1 reference)

url:https://www.cdc.gov/radiation-emergencies/hcp/clinical-guidance/ars.html SUPPORT DIRECT BACKGROUND Other

"The recovery process lasts from several weeks up to two years."

Recovery time is variable rather than a fixed sequence of subsyndromes.

🔬

Clinical Trials

NCT02343133 PHASE_II COMPLETED

Safety Study of HemaMax™ (rHuIL-12) to Treat Acute Radiation Syndrome. Safety/pharmacology research in healthy volunteers; it does not test survival benefit in ARS casualties.

Show evidence (1 reference)

clinicaltrials:NCT02343133 SUPPORT DIRECT Human Clinical

Registry description establishes the study purpose and population; it is not an efficacy result.

NCT01742221 PHASE_I COMPLETED

Safety and Tolerability of HemaMax™ (rHuIL-12) as Radiation Countermeasure. Safety/pharmacology research in healthy volunteers; it does not test survival benefit in ARS casualties.

Show evidence (1 reference)

clinicaltrials:NCT01742221 SUPPORT DIRECT Human Clinical

"This trial is designed to evaluate the safety, pharmacokinetics, and pharmacodynamics of HemaMax in healthy male and female volunteers."

Registry description establishes the study purpose and population; it is not an efficacy result.

NCT03585803 PHASE_I COMPLETED

A Clinical Trial to Evaluate Safety, Tolerability and Pharmacokinetic/Pharmacodynamic Characteristics of KMRC 011. Safety/pharmacology research in healthy volunteers; it does not test survival benefit in ARS casualties.

Show evidence (1 reference)

clinicaltrials:NCT03585803 SUPPORT DIRECT Human Clinical

"This trial is designed to evaluate the safety, tolerability, pharmacokinetic and pharmacodynamic of KMRC011 injection in healthy adult volunteers."

Registry description establishes the study purpose and population; it is not an efficacy result.

NCT06741345 PHASE_I COMPLETED

Phase 1 BIO 300 Oral Suspension. Safety/pharmacology research in healthy volunteers; it does not test survival benefit in ARS casualties.

Show evidence (1 reference)

clinicaltrials:NCT06741345 SUPPORT DIRECT Human Clinical

"This is a two-part study of BIO 300 Oral Suspension in healthy male and female volunteers."

Registry description establishes the study purpose and population; it is not an efficacy result.

NCT03797040 PHASE_I UNKNOWN

Open-label Phase I Study for PEP or Treatment of HS-ARS PLX-R 18 for the Post-Exposure Prevention (PEP) or Treatment of Hematopoietic Syndrome of Acute Radiation Syndrome (HS-ARS). A safety protocol for people exposed to ionizing radiation; registration alone does not document enrollment or benefit.

Show evidence (1 reference)

clinicaltrials:NCT03797040 SUPPORT DIRECT Human Clinical

"The objective of the study is to evaluate the safety of intramuscular (IM) administration of PLX-R18 in subjects exposed to ionizing radiation and who are at risk of developing HS-ARS."

Registry description establishes the study purpose and population; it is not an efficacy result.

NCT04650555 PHASE_I COMPLETED

BIO 300 Oral Powder Safety and Pharmacokinetics. Safety/pharmacology research in healthy volunteers; it does not test survival benefit in ARS casualties.

Show evidence (1 reference)

clinicaltrials:NCT04650555 SUPPORT DIRECT Human Clinical

"Open-label, single ascending dose and multiple single dose study in healthy volunteers to evaluate the safety and pharmacokinetics of BIO 300 Oral Powder (BIO 300). The single ascending dose study consists of 4 ascending dose cohorts and the multiple single dose study consists of a single dose..."

Registry description establishes the study purpose and population; it is not an efficacy result.

NCT00504335 PHASE_I COMPLETED

Safety and Pharmacokinetic Study of BIO 300 Capsules. Safety/pharmacology research in healthy volunteers; it does not test survival benefit in ARS casualties.

Show evidence (1 reference)

clinicaltrials:NCT00504335 SUPPORT DIRECT Human Clinical

"This trial is designed to evaluate the safety and pharmacokinetics of BIO 300 capsules when administered orally to healthy male and female volunteers."

Registry description establishes the study purpose and population; it is not an efficacy result.

NCT02587442 PHASE_I UNKNOWN

A Study to Evaluate the Safety and Pharmacokinetics of RadProtect® in Healthy Volunteers. Safety/pharmacology research in healthy volunteers; it does not test survival benefit in ARS casualties.

Show evidence (1 reference)

clinicaltrials:NCT02587442 SUPPORT DIRECT Human Clinical

"This is a Phase 1, non-randomized, sequential-cohort, dose escalation, open-label study designed to evaluate the safety and tolerability of RadProtect® in healthy volunteers. This study is to be conducted at two clinical centers and in conformity with Good Clinical Practice (GCP)."

Registry description establishes the study purpose and population; it is not an efficacy result.

🧫

Experimental Models

Irradiated resting human lymphocytes PRIMARY_CELL_CULTURE

Resting lymphocytes were irradiated with cobalt-60 gamma rays or fast neutrons and evaluated for apoptosis after 24 hours of culture. Doses ranged from 0.05 to 5 Gy.

Organism

Homo sapiens NCBITaxon:9606

Cell source

Primary peripheral-blood lymphocytes from healthy donors.

Publication

PMID:9525257

Pathograph links

Mature Lymphocyte Apoptosis recapitulates fidelity: moderate Demonstrates early interphase apoptosis in nondividing lymphocytes.

Limitations: Ex-vivo assay, not whole-body exposure or an ARS patient cohort; it does not alone establish clinical depletion kinetics.

Readouts

Apoptotic lymphocyte yield

Direction: INCREASED

Interpretation: Apoptotic yield increased steeply below 1 Gy and flattened toward 5 Gy.

Show evidence (1 reference)

PMID:9525257 SUPPORT DIRECT PRIMARY RESULT In Vitro

"Dose-response curves obtained with both radiation qualities were characterized by an initial steep increase in the number of apoptotic cells below 1 Gy, with a flattening of the curves at higher doses towards 5 Gy."

Measured ex-vivo dose response.

Show evidence (1 reference)

PMID:9525257 SUPPORT DIRECT PRIMARY RESULT In Vitro

"The dose-response data confirm the high radiosensitivity of lymphocytes and demonstrate that their response to undergo early interphase cell death by apoptosis is largely independent of LET."

Resting human lymphocytes underwent apoptosis after ex-vivo irradiation; cell division is not required.

Healthy-donor blood dicentric biodosimetry assay PRIMARY_CELL_CULTURE

DLADES dose-response calibration used blood from two donors irradiated with cobalt-60 gamma rays at 0–4 Gy and 0.8 Gy/min. Two other donors provided blinded samples. Chromosome-number filtering improved image selection.

Organism

Homo sapiens NCBITaxon:9606

Cell source

Healthy-donor peripheral blood, with cultured mononuclear cells.

Publication

PMID:36543843

Pathograph links

Radiation-Induced Chromosomal Aberrations measures fidelity: moderate Measures acquired dicentrics for calibrated dose estimation.

Limitations: Healthy blood irradiated ex vivo, not ARS casualties; only four donors overall. The blinded evaluation spanned 0.5–4 Gy. The 0.5 Gy sample had no finite lower confidence bound; lower/higher doses, heterogeneous exposures and other radiation qualities were not validated.

Readouts

Blind-sample dose reconstruction

Interpretation: The known doses lay within the reported 95% confidence limits after quality filtering, with an undefined lower bound for the 0.5 Gy sample.

Show evidence (1 reference)

PMID:36543843 SUPPORT DIRECT PRIMARY RESULT In Vitro

"The actual dose for each sample was within the 95% confidence limits of the estimated dose."

Performance finding applies only to the tested ex-vivo samples.

Show evidence (1 reference)

PMID:36543843 SUPPORT DIRECT PRIMARY RESULT In Vitro

"Blood samples from two donors were exposed to cobalt-60 gamma rays (0-4 Gy, 0.8 Gy/min)."

Abstract specifies the calibration exposure.

🐁

Animal Models

Rhesus macaque filgrastim total-body irradiation study

Randomized blinded study in 46 rhesus macaques given 7.5 Gy total-body LINAC irradiation at 0.8 Gy/min, with medical management in both arms. Filgrastim began 23±3 hours after irradiation; 24 treated animals were compared with 22 controls.

Species

Macaca mulatta

Publication

PMID:23210705

Pathograph links

Bone Marrow Hematopoietic Suppression recapitulates fidelity: moderate Reproduces hematopoietic suppression and measures filgrastim-associated survival under this protocol.

Limitations: Controlled total-body irradiation, treatment timing and supportive care differ from heterogeneous accidental exposure. This experiment supports filgrastim; it is not the sole efficacy study for all approved drugs. It does not establish human dose equivalence or gastrointestinal/neurovascular rescue.

Readouts

60-day overall mortality

Direction: DECREASED

Interpretation: Filgrastim reduced 60-day mortality from 59.1% to 20.8% at an approximate LD 50/60 dose.

Show evidence (1 reference)

PMID:23210705 SUPPORT Model Organism

"Filgrastim significantly (P < 0.004) reduced 60 day overall mortality [20.8% (5/24)] compared to the controls [59.1% (13/22)]."

The survival readout that carries the efficacy claim for this model.

Show evidence (2 references)

PMID:23210705 SUPPORT Model Organism

"We evaluated the efficacy of filgrastim to increase survival of nonhuman primates (NHP) exposed to an approximate mid-lethal dose"

Establishes the model, species and dose regimen this entry's efficacy evidence comes from.

+ 1 more reference

Multilineage Peripheral Cytopenias recapitulates fidelity: moderate Reproduces the peripheral cytopenia phase and measures filgrastim's effect on the duration of neutropenia under this protocol.

Limitations: Controlled total-body irradiation, treatment timing and supportive care differ from heterogeneous accidental exposure. Filgrastim shortened the duration of neutropenia without changing the absolute neutrophil count nadir, so this readout does not show that the depth of the cytopenia is rescued, and it does not transfer to other countermeasures.

Readouts

Duration of neutropenia

Direction: DECREASED

Interpretation: Filgrastim shortened neutropenia in this experiment; the ANC nadir did not differ significantly.

Show evidence (1 reference)

PMID:23210705 SUPPORT DIRECT PRIMARY RESULT Model Organism

"Filgrastim significantly decreased the duration of neutropenia, but did not affect the absolute neutrophil count nadir."

The duration-versus-nadir result applies to this regimen and does not define every countermeasure.

Rhesus macaque pegfilgrastim irradiation study

The FDA label describes a randomized placebo-controlled study with 23 animals per arm, 7.50±0.15 Gy total-body irradiation at 0.8±0.03 Gy/min, pegfilgrastim on days 1 and 8, and medical management including fluids, antibiotics and transfusions.

Species

Macaca mulatta

Publication

url:https://www.accessdata.fda.gov/drugsatfda_docs/label/2015/125031s180lbl.pdf

Pathograph links

Bone Marrow Hematopoietic Suppression partially recapitulates fidelity: moderate Models hematopoietic injury and tests an intervention-associated survival outcome.

Limitations: Controlled exposure, species and protocol-defined care limit transfer to human casualties. Survival is an integrated outcome and does not prove rescue of every organ injury.

Readouts

60-day survival

Direction: INCREASED

Interpretation: Pegfilgrastim increased 60-day survival under this two-dose protocol.

Show evidence (1 reference)

url:https://www.accessdata.fda.gov/drugsatfda_docs/label/2015/125031s180lbl.pdf SUPPORT DIRECT REVIEW SYNTHESIS Model Organism

"91% survival (21/23) in the pegfilgrastim group compared to 48% survival (11/23) in the control group."

Pegfilgrastim increased 60-day survival under this two-dose protocol.

Show evidence (1 reference)

url:https://www.accessdata.fda.gov/drugsatfda_docs/label/2015/125031s180lbl.pdf SUPPORT DIRECT REVIEW SYNTHESIS Model Organism

"91% survival (21/23) in the pegfilgrastim group compared to 48% survival (11/23) in the control group."

Pegfilgrastim increased 60-day survival under this two-dose protocol.

Rhesus macaque romiplostim irradiation study

The FDA label describes a randomized blinded placebo-controlled study with 40 animals per arm, 6.8 Gy cobalt-60 total-body irradiation, romiplostim 24 hours later and medical management. A combination arm was exploratory.

Species

Macaca mulatta

Publication

url:https://www.accessdata.fda.gov/drugsatfda_docs/label/2021/125268s167lbl.pdf

Pathograph links

Bone Marrow Hematopoietic Suppression partially recapitulates fidelity: moderate Models hematopoietic injury and tests an intervention-associated survival outcome.

Limitations: Controlled exposure, species and protocol-defined care limit transfer to human casualties. Survival is an integrated outcome and does not prove rescue of every organ injury.

Readouts

60-day survival

Direction: INCREASED

Interpretation: Romiplostim increased 60-day survival by 40 percentage points in the monotherapy comparison; this is not a human effect estimate.

Show evidence (1 reference)

url:https://www.accessdata.fda.gov/drugsatfda_docs/label/2021/125268s167lbl.pdf SUPPORT DIRECT REVIEW SYNTHESIS Model Organism

"72.5% survival (29/40) in the Nplate group compared to 32.5% survival (13/40) in the control group."

Romiplostim increased 60-day survival by 40 percentage points in the monotherapy comparison; this is not a human effect estimate.

Show evidence (1 reference)

url:https://www.accessdata.fda.gov/drugsatfda_docs/label/2021/125268s167lbl.pdf SUPPORT DIRECT REVIEW SYNTHESIS Model Organism

"72.5% survival (29/40) in the Nplate group compared to 32.5% survival (13/40) in the control group."

Romiplostim increased 60-day survival by 40 percentage points in the monotherapy comparison; this is not a human effect estimate.

{ }

Source YAML

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name: Acute Radiation Syndrome
creation_date: '2026-09-01T14:00:00Z'
description: 'Acute radiation syndrome follows whole-body or substantial partial-body exposure to a high dose of penetrating ionizing radiation over a short interval. Injury can involve hematopoietic, gastrointestinal, cutaneous and neurovascular tissues in combination. Dose thresholds do not determine chronological order: early lymphocyte loss and prodromal symptoms can precede marrow failure over subsequent weeks, whereas very-high-dose neurovascular injury can become fatal within days. Dose distribution, radiation quality, concurrent injuries and supportive care influence outcome. Growth factors and a thrombopoietin-receptor agonist target the hematopoietic component; gastrointestinal and other organ injuries require additional supportive care.'
categories:
- Environmental Health Disorder
- Toxic Exposure Disorder
category: Complex
parents:
- Radiation Injury
disease_term:
  preferred_term: acute radiation syndrome
  term:
    id: MONDO:0033938
    label: acute radiation syndrome
pathophysiology:
- name: Radiation-Induced DNA Double-Strand Breaks
  description: Ionizing radiation induces DNA double-strand breaks that activate cellular DNA-damage responses. DNA repair, apoptosis, senescence, and chromosome misrepair are downstream cell-context-dependent outcomes of this proximal lesion.
  role: trigger
  biological_scale: MOLECULAR
  evidence:
  - reference: PMID:24124731
    reference_title: Hematopoietic stem cell injury induced by ionizing radiation.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: IR induces several different types of damage to DNA, which include base damages and changes, cross linking, single-strand breaks, and double-strand breaks (DSBs).
    explanation: This review places double-strand breaks in the ionizing-radiation DNA-damage response.
    directness: DIRECT
    quote_role: REVIEW_SYNTHESIS
  - reference: PMID:36543843
    reference_title: Dicentric chromosome assay using a deep learning-based automated system.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: Radiation-induced DNA double-strand breaks activate cellular damage repair mechanisms. However, misrepair of chromosomes results in chromosomal aberrations, typically dicentric chromosomes and translocations
    explanation: The assay paper describes double-strand breaks as an early molecular lesion after irradiation.
    directness: DIRECT
    quote_role: BACKGROUND
  biological_processes:
  - preferred_term: DNA damage response
    term:
      id: GO:0006974
      label: DNA damage response
    modifier: INCREASED
  downstream:
  - target: Hematopoietic Progenitor Injury
    description: DNA damage is upstream of radiation-induced loss of mitotic and survival capacity in marrow stem/progenitor cells.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:24124731
      reference_title: Hematopoietic stem cell injury induced by ionizing radiation.
      supports: SUPPORT
      evidence_source: OTHER
      snippet: DSBs can effectively trigger a series of cellular reactions termed DNA damage response (DDR) to ensure the rapid detection and repair of DSBs or to remove the damaged cells via the induction of apoptosis and senescence to maintain genome integrity.
      explanation: The review describes DSB-triggered damage-response signaling that can remove irradiated cells by apoptosis or senescence.
      directness: INDIRECT
      quote_role: REVIEW_SYNTHESIS
    - reference: PMID:24124731
      reference_title: Hematopoietic stem cell injury induced by ionizing radiation.
      supports: SUPPORT
      evidence_source: OTHER
      snippet: Induction of apoptosis in HSCs and hematopoietic progenitor cells is primarily responsible for IR-induced acute bone marrow (BM) injury.
      explanation: The HSC-injury review identifies HSC/HPC apoptosis as the proximate cellular route from ionizing-radiation damage to acute marrow injury.
      directness: DIRECT
      quote_role: REVIEW_SYNTHESIS
  - target: Radiation-Induced Chromosomal Aberrations
    description: Misrepair of DNA double-strand breaks generates dicentric chromosomes and translocations.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:36543843
      reference_title: Dicentric chromosome assay using a deep learning-based automated system.
      supports: SUPPORT
      evidence_source: OTHER
      snippet: Radiation-induced DNA double-strand breaks activate cellular damage repair mechanisms. However, misrepair of chromosomes results in chromosomal aberrations, typically dicentric chromosomes and translocations
      explanation: The assay paper explains that misrepair of radiation-induced DNA breaks causes the acquired chromosome aberrations used in biodosimetry.
      directness: DIRECT
      quote_role: BACKGROUND
- name: Hematopoietic Progenitor Injury
  description: Radiation impairs survival and proliferative capacity of marrow stem/progenitor cells and their progeny. Radiosensitivity does not mean every hematopoietic stem cell is rapidly cycling. Surviving marrow reserve helps determine reversibility.
  role: trigger
  biological_scale: CELLULAR
  evidence:
  - reference: PMID:21987000
    reference_title: First global consensus for evidence-based management of the hematopoietic syndrome resulting from exposure to ionizing radiation.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: The primary causes of HS are radiation-induced suppression of mitosis in hematopoietic stem/progenitor cells and their progeny, resulting in hypocellularity and aplasia of the bone marrow and apoptosis in lymphocytes and other hematopoietic cells.
    explanation: The consensus distinguishes impaired marrow production from radiation-induced lymphocyte apoptosis.
    directness: DIRECT
    quote_role: REVIEW_SYNTHESIS
  conforms_to: myelosuppression#Cytotoxic Insult to Proliferating Hematopoietic Progenitors
  cell_types:
  - preferred_term: hematopoietic stem cell
    term:
      id: CL:0000037
      label: hematopoietic stem cell
  - preferred_term: hematopoietic precursor cell
    term:
      id: CL:0008001
      label: hematopoietic precursor cell
  locations:
  - preferred_term: bone marrow
    term:
      id: UBERON:0002371
      label: bone marrow
  biological_processes:
  - preferred_term: cellular response to ionizing radiation
    term:
      id: GO:0071479
      label: cellular response to ionizing radiation
    modifier: INCREASED
  downstream:
  - target: Bone Marrow Hematopoietic Suppression
    description: Loss of functional progenitors reduces hematopoietic capacity.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:21987000
      reference_title: First global consensus for evidence-based management of the hematopoietic syndrome resulting from exposure to ionizing radiation.
      supports: SUPPORT
      evidence_source: OTHER
      snippet: The primary causes of HS are radiation-induced suppression of mitosis in hematopoietic stem/progenitor cells and their progeny, resulting in hypocellularity and aplasia of the bone marrow and apoptosis in lymphocytes and other hematopoietic cells.
      explanation: The consensus distinguishes impaired marrow production from radiation-induced lymphocyte apoptosis.
      directness: DIRECT
      quote_role: REVIEW_SYNTHESIS
- name: Bone Marrow Hematopoietic Suppression
  description: Reduced marrow cellularity and hematopoietic output follow progenitor injury. Recovery can arise from residual endogenous cells; severe aplasia may persist. Exposure heterogeneity and associated organ injury affect recovery.
  role: central_effector
  biological_scale: TISSUE
  evidence:
  - reference: PMID:21987000
    reference_title: First global consensus for evidence-based management of the hematopoietic syndrome resulting from exposure to ionizing radiation.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: The primary causes of HS are radiation-induced suppression of mitosis in hematopoietic stem/progenitor cells and their progeny, resulting in hypocellularity and aplasia of the bone marrow and apoptosis in lymphocytes and other hematopoietic cells.
    explanation: The consensus distinguishes impaired marrow production from radiation-induced lymphocyte apoptosis.
    directness: DIRECT
    quote_role: REVIEW_SYNTHESIS
  conforms_to: myelosuppression#Bone Marrow Hematopoietic Suppression
  locations:
  - preferred_term: bone marrow
    term:
      id: UBERON:0002371
      label: bone marrow
  downstream:
  - target: Multilineage Peripheral Cytopenias
    description: Reduced production produces delayed depletion of circulating blood-cell lineages.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:21987000
      reference_title: First global consensus for evidence-based management of the hematopoietic syndrome resulting from exposure to ionizing radiation.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: Depending on the dose, dose rate, and radiation quality factor, various degrees of pancytopenia develop over several weeks after whole-body or significant partial-body exposure.
      explanation: Clinical synthesis supports dose-dependent cytopenias developing over weeks.
      directness: DIRECT
      quote_role: REVIEW_SYNTHESIS
  - target: Bone marrow hypocellularity
    description: Marrow hypocellularity is a tissue manifestation of reduced hematopoiesis.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:21987000
      reference_title: First global consensus for evidence-based management of the hematopoietic syndrome resulting from exposure to ionizing radiation.
      supports: SUPPORT
      evidence_source: OTHER
      snippet: The primary causes of HS are radiation-induced suppression of mitosis in hematopoietic stem/progenitor cells and their progeny, resulting in hypocellularity and aplasia of the bone marrow and apoptosis in lymphocytes and other hematopoietic cells.
      explanation: The consensus distinguishes impaired marrow production from radiation-induced lymphocyte apoptosis.
      directness: DIRECT
      quote_role: REVIEW_SYNTHESIS
- name: Multilineage Peripheral Cytopenias
  description: Neutropenia, thrombocytopenia and anemia develop with kinetics influenced by lineage turnover, dose and surviving progenitors. Early lymphopenia also reflects direct apoptosis of mature lymphocytes and is represented separately.
  role: effector
  biological_scale: ORGANISM
  evidence:
  - reference: PMID:21987000
    reference_title: First global consensus for evidence-based management of the hematopoietic syndrome resulting from exposure to ionizing radiation.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Depending on the dose, dose rate, and radiation quality factor, various degrees of pancytopenia develop over several weeks after whole-body or significant partial-body exposure.
    explanation: Clinical synthesis supports dose-dependent cytopenias developing over weeks.
    directness: DIRECT
    quote_role: REVIEW_SYNTHESIS
  conforms_to: myelosuppression#Multilineage Peripheral Cytopenias
  downstream:
  - target: Decreased total neutrophil count
    description: Granulocyte production declines.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:21987000
      reference_title: First global consensus for evidence-based management of the hematopoietic syndrome resulting from exposure to ionizing radiation.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: Depending on the dose, dose rate, and radiation quality factor, various degrees of pancytopenia develop over several weeks after whole-body or significant partial-body exposure.
      explanation: Clinical synthesis supports dose-dependent cytopenias developing over weeks.
      directness: DIRECT
      quote_role: REVIEW_SYNTHESIS
  - target: Thrombocytopenia
    description: Platelet production declines.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:21987000
      reference_title: First global consensus for evidence-based management of the hematopoietic syndrome resulting from exposure to ionizing radiation.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: Depending on the dose, dose rate, and radiation quality factor, various degrees of pancytopenia develop over several weeks after whole-body or significant partial-body exposure.
      explanation: Clinical synthesis supports dose-dependent cytopenias developing over weeks.
      directness: DIRECT
      quote_role: REVIEW_SYNTHESIS
  - target: Anemia
    description: Erythrocyte depletion can follow sustained marrow suppression; it is generally later than neutropenia.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:21987000
      reference_title: First global consensus for evidence-based management of the hematopoietic syndrome resulting from exposure to ionizing radiation.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: Depending on the dose, dose rate, and radiation quality factor, various degrees of pancytopenia develop over several weeks after whole-body or significant partial-body exposure.
      explanation: Clinical synthesis supports dose-dependent cytopenias developing over weeks.
      directness: DIRECT
      quote_role: REVIEW_SYNTHESIS
  - target: Pancytopenia
    description: Multiple blood-cell lineages may be reduced.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:21987000
      reference_title: First global consensus for evidence-based management of the hematopoietic syndrome resulting from exposure to ionizing radiation.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: Depending on the dose, dose rate, and radiation quality factor, various degrees of pancytopenia develop over several weeks after whole-body or significant partial-body exposure.
      explanation: Clinical synthesis supports dose-dependent cytopenias developing over weeks.
      directness: DIRECT
      quote_role: REVIEW_SYNTHESIS
  - target: Neutropenic Infection Susceptibility
    description: Loss of neutrophil defense increases infection risk.
    causal_link_type: DIRECT
    evidence:
    - reference: url:https://www.fda.gov/emergency-preparedness-and-response/medical-countermeasure-mcm-issues/radiological-and-nuclear-emergency-preparedness
      reference_title: Radiological and Nuclear Emergency Preparedness | FDA
      supports: SUPPORT
      evidence_source: OTHER
      snippet: Severe neutropenia increases the risk of sepsis and death due to infections, while thrombocytopenia increases the risk of hemorrhage and death due to bleeding.
      explanation: FDA describes the distinct infection and bleeding consequences of marrow injury.
      directness: DIRECT
      quote_role: BACKGROUND
  - target: Impaired Primary Hemostasis
    description: Thrombocytopenia impairs hemostasis.
    causal_link_type: DIRECT
    evidence:
    - reference: url:https://www.fda.gov/emergency-preparedness-and-response/medical-countermeasure-mcm-issues/radiological-and-nuclear-emergency-preparedness
      reference_title: Radiological and Nuclear Emergency Preparedness | FDA
      supports: SUPPORT
      evidence_source: OTHER
      snippet: Severe neutropenia increases the risk of sepsis and death due to infections, while thrombocytopenia increases the risk of hemorrhage and death due to bleeding.
      explanation: FDA describes the distinct infection and bleeding consequences of marrow injury.
      directness: DIRECT
      quote_role: BACKGROUND
- name: Neutropenic Infection Susceptibility
  description: Neutrophil depletion increases susceptibility to infection, including potentially lethal sepsis. This is an acute vulnerability; recurrent infections are not required.
  role: consequence
  biological_scale: ORGANISM
  evidence:
  - reference: url:https://www.fda.gov/emergency-preparedness-and-response/medical-countermeasure-mcm-issues/radiological-and-nuclear-emergency-preparedness
    reference_title: Radiological and Nuclear Emergency Preparedness | FDA
    supports: SUPPORT
    evidence_source: OTHER
    snippet: Severe neutropenia increases the risk of sepsis and death due to infections, while thrombocytopenia increases the risk of hemorrhage and death due to bleeding.
    explanation: FDA describes the distinct infection and bleeding consequences of marrow injury.
    directness: DIRECT
    quote_role: BACKGROUND
  downstream:
  - target: Sepsis
    description: Infection can progress to systemic illness in the neutropenic host.
    causal_link_type: DIRECT
    evidence:
    - reference: url:https://www.fda.gov/emergency-preparedness-and-response/medical-countermeasure-mcm-issues/radiological-and-nuclear-emergency-preparedness
      reference_title: Radiological and Nuclear Emergency Preparedness | FDA
      supports: SUPPORT
      evidence_source: OTHER
      snippet: Severe neutropenia increases the risk of sepsis and death due to infections, while thrombocytopenia increases the risk of hemorrhage and death due to bleeding.
      explanation: FDA describes the distinct infection and bleeding consequences of marrow injury.
      directness: DIRECT
      quote_role: BACKGROUND
- name: Impaired Primary Hemostasis
  description: Reduced circulating platelets increase bleeding risk during hematopoietic radiation injury.
  role: consequence
  biological_scale: ORGANISM
  evidence:
  - reference: url:https://www.fda.gov/emergency-preparedness-and-response/medical-countermeasure-mcm-issues/radiological-and-nuclear-emergency-preparedness
    reference_title: Radiological and Nuclear Emergency Preparedness | FDA
    supports: SUPPORT
    evidence_source: OTHER
    snippet: Severe neutropenia increases the risk of sepsis and death due to infections, while thrombocytopenia increases the risk of hemorrhage and death due to bleeding.
    explanation: FDA describes the distinct infection and bleeding consequences of marrow injury.
    directness: DIRECT
    quote_role: BACKGROUND
  downstream:
  - target: Petechiae
    description: Thrombocytopenic bleeding may manifest as petechiae.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:21987000
      reference_title: First global consensus for evidence-based management of the hematopoietic syndrome resulting from exposure to ionizing radiation.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: Petechiae, easy bruising, normal hemoglobin level
      explanation: The hematopoietic toxicity table explicitly includes petechiae.
      directness: DIRECT
      quote_role: REVIEW_SYNTHESIS
- name: Mature Lymphocyte Apoptosis
  description: Resting lymphocytes are highly radiosensitive and can undergo early interphase apoptosis. This mechanism contributes to early lymphocyte depletion independently of delayed loss of marrow output.
  role: trigger
  biological_scale: CELLULAR
  evidence:
  - reference: PMID:9525257
    reference_title: Apoptosis induced by fast neutrons versus 60Co gamma-rays in human peripheral blood lymphocytes.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: The dose-response data confirm the high radiosensitivity of lymphocytes and demonstrate that their response to undergo early interphase cell death by apoptosis is largely independent of LET.
    explanation: Resting human lymphocytes underwent apoptosis after ex-vivo irradiation; cell division is not required.
    directness: DIRECT
    quote_role: PRIMARY_RESULT
  cell_types:
  - preferred_term: lymphocyte
    term:
      id: CL:0000542
      label: lymphocyte
  biological_processes:
  - preferred_term: apoptotic process
    term:
      id: GO:0006915
      label: apoptotic process
    modifier: INCREASED
  downstream:
  - target: Decreased total lymphocyte count
    description: Apoptosis contributes to early lymphocyte depletion.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:21987000
      reference_title: First global consensus for evidence-based management of the hematopoietic syndrome resulting from exposure to ionizing radiation.
      supports: SUPPORT
      evidence_source: OTHER
      snippet: The primary causes of HS are radiation-induced suppression of mitosis in hematopoietic stem/progenitor cells and their progeny, resulting in hypocellularity and aplasia of the bone marrow and apoptosis in lymphocytes and other hematopoietic cells.
      explanation: The consensus distinguishes impaired marrow production from radiation-induced lymphocyte apoptosis.
      directness: DIRECT
      quote_role: REVIEW_SYNTHESIS
    - reference: PMID:9525257
      reference_title: Apoptosis induced by fast neutrons versus 60Co gamma-rays in human peripheral blood lymphocytes.
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: The dose-response data confirm the high radiosensitivity of lymphocytes and demonstrate that their response to undergo early interphase cell death by apoptosis is largely independent of LET.
      explanation: Resting human lymphocytes underwent apoptosis after ex-vivo irradiation; cell division is not required.
      directness: DIRECT
      quote_role: PRIMARY_RESULT
- name: Intestinal Epithelial Injury
  description: Radiation destroys cells of the intestinal epithelial lining, reducing mucosal integrity. Gastrointestinal and marrow injury can coexist.
  role: trigger
  biological_scale: CELLULAR
  evidence:
  - reference: PMID:21986999
    reference_title: Literature review and global consensus on management of acute radiation syndrome affecting nonhematopoietic organ systems.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: Destruction of the intestinal epithelial lining causes breakdown of the mucosal barrier that normally separates the contents of the intestinal lumen from the GI tissue, resulting in severe secretory diarrhea, dehydration, and electrolyte imbalance.
    explanation: Consensus links epithelial destruction to loss of barrier function and gastrointestinal fluid losses.
    directness: DIRECT
    quote_role: REVIEW_SYNTHESIS
  cell_types:
  - preferred_term: intestinal epithelial cell
    term:
      id: CL:0002563
      label: intestinal epithelial cell
  locations:
  - preferred_term: small intestine
    term:
      id: UBERON:0002108
      label: small intestine
  downstream:
  - target: Intestinal Barrier Failure
    description: Loss of the epithelial lining disrupts the mucosal barrier.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:21986999
      reference_title: Literature review and global consensus on management of acute radiation syndrome affecting nonhematopoietic organ systems.
      supports: SUPPORT
      evidence_source: OTHER
      snippet: Destruction of the intestinal epithelial lining causes breakdown of the mucosal barrier that normally separates the contents of the intestinal lumen from the GI tissue, resulting in severe secretory diarrhea, dehydration, and electrolyte imbalance.
      explanation: Consensus links epithelial destruction to loss of barrier function and gastrointestinal fluid losses.
      directness: DIRECT
      quote_role: REVIEW_SYNTHESIS
- name: Intestinal Barrier Failure
  description: Loss of mucosal integrity permits intestinal fluid loss and microbial passage across the bowel wall.
  role: effector
  biological_scale: TISSUE
  evidence:
  - reference: PMID:21986999
    reference_title: Literature review and global consensus on management of acute radiation syndrome affecting nonhematopoietic organ systems.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: Destruction of the intestinal epithelial lining causes breakdown of the mucosal barrier that normally separates the contents of the intestinal lumen from the GI tissue, resulting in severe secretory diarrhea, dehydration, and electrolyte imbalance.
    explanation: Consensus links epithelial destruction to loss of barrier function and gastrointestinal fluid losses.
    directness: DIRECT
    quote_role: REVIEW_SYNTHESIS
  - reference: PMID:21986999
    reference_title: Literature review and global consensus on management of acute radiation syndrome affecting nonhematopoietic organ systems.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: bacterial translocation (passage of bacteria from the intestinal lumen through the defective mucosal barrier and into the bloodstream), which may occur coincident with the period of severe compromise of cell-mediated immunity.
    explanation: Barrier failure provides a route for enteric organisms to reach the circulation; marrow injury increases vulnerability.
    directness: DIRECT
    quote_role: REVIEW_SYNTHESIS
  downstream:
  - target: Diarrhea
    description: Mucosal injury causes secretory diarrhea.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:21986999
      reference_title: Literature review and global consensus on management of acute radiation syndrome affecting nonhematopoietic organ systems.
      supports: SUPPORT
      evidence_source: OTHER
      snippet: Destruction of the intestinal epithelial lining causes breakdown of the mucosal barrier that normally separates the contents of the intestinal lumen from the GI tissue, resulting in severe secretory diarrhea, dehydration, and electrolyte imbalance.
      explanation: Consensus links epithelial destruction to loss of barrier function and gastrointestinal fluid losses.
      directness: DIRECT
      quote_role: REVIEW_SYNTHESIS
  - target: Dehydration
    description: Gastrointestinal fluid loss can produce dehydration.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:21986999
      reference_title: Literature review and global consensus on management of acute radiation syndrome affecting nonhematopoietic organ systems.
      supports: SUPPORT
      evidence_source: OTHER
      snippet: Destruction of the intestinal epithelial lining causes breakdown of the mucosal barrier that normally separates the contents of the intestinal lumen from the GI tissue, resulting in severe secretory diarrhea, dehydration, and electrolyte imbalance.
      explanation: Consensus links epithelial destruction to loss of barrier function and gastrointestinal fluid losses.
      directness: DIRECT
      quote_role: REVIEW_SYNTHESIS
  - target: Enteric Bacterial Translocation
    description: The damaged mucosal barrier permits enteric bacteria to cross into tissue and blood.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:21986999
      reference_title: Literature review and global consensus on management of acute radiation syndrome affecting nonhematopoietic organ systems.
      supports: SUPPORT
      evidence_source: OTHER
      snippet: bacterial translocation (passage of bacteria from the intestinal lumen through the defective mucosal barrier and into the bloodstream), which may occur coincident with the period of severe compromise of cell-mediated immunity.
      explanation: Barrier failure provides a route for enteric organisms to reach the circulation; marrow injury increases vulnerability.
      directness: DIRECT
      quote_role: REVIEW_SYNTHESIS
- name: Enteric Bacterial Translocation
  description: Enteric bacteria can cross the radiation-injured mucosa into the circulation, particularly during concomitant immune compromise.
  role: intermediate
  biological_scale: TISSUE
  evidence:
  - reference: PMID:21986999
    reference_title: Literature review and global consensus on management of acute radiation syndrome affecting nonhematopoietic organ systems.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: bacterial translocation (passage of bacteria from the intestinal lumen through the defective mucosal barrier and into the bloodstream), which may occur coincident with the period of severe compromise of cell-mediated immunity.
    explanation: Barrier failure provides a route for enteric organisms to reach the circulation; marrow injury increases vulnerability.
    directness: DIRECT
    quote_role: REVIEW_SYNTHESIS
  downstream:
  - target: Sepsis
    description: Translocated bacteria can cause systemic infection.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:21986999
      reference_title: Literature review and global consensus on management of acute radiation syndrome affecting nonhematopoietic organ systems.
      supports: SUPPORT
      evidence_source: OTHER
      snippet: Hence, it has been postulated that sepsis from enteric bacteria is a potential cause of death, regardless of radiation dose.
      explanation: The review identifies a proposed route to sepsis and preserves its inferential status.
      directness: INDIRECT
      quote_role: REVIEW_SYNTHESIS
- name: Basal Epidermal Injury
  description: Radiation injury to the basal epidermis impairs skin integrity and produces local inflammation. Skin involvement can evolve after an initially quiet interval.
  role: trigger
  biological_scale: CELLULAR
  evidence:
  - reference: url:https://www.cdc.gov/radiation-emergencies/hcp/clinical-guidance/ars.html
    reference_title: 'Acute Radiation Syndrome: Information for Clinicians | Radiation Emergencies | CDC'
    supports: SUPPORT
    evidence_source: OTHER
    snippet: When the basal cell layer of the skin is damaged by radiation, inflammation, erythema, and dry or moist desquamation can occur.
    explanation: CDC links basal epidermal injury to local cutaneous manifestations.
    directness: DIRECT
    quote_role: BACKGROUND
  locations:
  - preferred_term: skin of body
    term:
      id: UBERON:0002097
      label: skin of body
  downstream:
  - target: Erythema
    description: Local skin inflammation causes erythema.
    causal_link_type: DIRECT
    evidence:
    - reference: url:https://www.cdc.gov/radiation-emergencies/hcp/clinical-guidance/ars.html
      reference_title: 'Acute Radiation Syndrome: Information for Clinicians | Radiation Emergencies | CDC'
      supports: SUPPORT
      evidence_source: OTHER
      snippet: When the basal cell layer of the skin is damaged by radiation, inflammation, erythema, and dry or moist desquamation can occur.
      explanation: CDC links basal epidermal injury to local cutaneous manifestations.
      directness: DIRECT
      quote_role: BACKGROUND
  - target: Abnormal blistering of the skin
    description: Injured skin may blister after the latent interval.
    causal_link_type: DIRECT
    evidence:
    - reference: url:https://www.cdc.gov/radiation-emergencies/hcp/clinical-guidance/ars.html
      reference_title: 'Acute Radiation Syndrome: Information for Clinicians | Radiation Emergencies | CDC'
      supports: SUPPORT
      evidence_source: OTHER
      snippet: when intense reddening, blistering, and ulceration of the irradiated site are visible.
      explanation: CDC describes delayed skin manifestations.
      directness: DIRECT
      quote_role: BACKGROUND
  - target: Skin ulcer
    description: Severe local injury can cause ulceration.
    causal_link_type: DIRECT
    evidence:
    - reference: url:https://www.cdc.gov/radiation-emergencies/hcp/clinical-guidance/ars.html
      reference_title: 'Acute Radiation Syndrome: Information for Clinicians | Radiation Emergencies | CDC'
      supports: SUPPORT
      evidence_source: OTHER
      snippet: when intense reddening, blistering, and ulceration of the irradiated site are visible.
      explanation: CDC describes delayed skin ulceration.
      directness: DIRECT
      quote_role: BACKGROUND
- name: Hair Follicle Injury
  description: Radiation can damage hair follicles and cause local epilation; reversibility depends on the extent of injury.
  role: trigger
  biological_scale: CELLULAR
  evidence:
  - reference: url:https://www.cdc.gov/radiation-emergencies/hcp/clinical-guidance/ars.html
    reference_title: 'Acute Radiation Syndrome: Information for Clinicians | Radiation Emergencies | CDC'
    supports: SUPPORT
    evidence_source: OTHER
    snippet: Also, hair follicles may be damaged, causing epilation.
    explanation: Hair-follicle injury is a separate cause of post-exposure hair loss.
    directness: DIRECT
    quote_role: BACKGROUND
  locations:
  - preferred_term: hair follicle
    term:
      id: UBERON:0002073
      label: hair follicle
  downstream:
  - target: Alopecia
    description: Hair-follicle damage produces epilation.
    causal_link_type: DIRECT
    evidence:
    - reference: url:https://www.cdc.gov/radiation-emergencies/hcp/clinical-guidance/ars.html
      reference_title: 'Acute Radiation Syndrome: Information for Clinicians | Radiation Emergencies | CDC'
      supports: SUPPORT
      evidence_source: OTHER
      snippet: Also, hair follicles may be damaged, causing epilation.
      explanation: Hair-follicle injury is a separate cause of post-exposure hair loss.
      directness: DIRECT
      quote_role: BACKGROUND
- name: Neurovascular Injury
  description: At very high exposures, vascular injury, permeability changes and inflammation may contribute to neurovascular collapse. The detailed human mechanism is incompletely resolved. This syndrome can develop faster than delayed marrow failure.
  role: trigger
  biological_scale: TISSUE
  evidence:
  - reference: PMID:21986999
    reference_title: Literature review and global consensus on management of acute radiation syndrome affecting nonhematopoietic organ systems.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: Several pathophysiologic processes may contribute to neurovascular collapse, including vascular damage, inflammation, cerebral edema, increased vascular permeability, and perivascular hemorrhage.
    explanation: The consensus presents contributing processes, not a single experimentally resolved human cascade.
    directness: INDIRECT
    quote_role: REVIEW_SYNTHESIS
  downstream:
  - target: Confusion
    description: Severe neurovascular injury is associated with this manifestation.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:21986999
      reference_title: Literature review and global consensus on management of acute radiation syndrome affecting nonhematopoietic organ systems.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: Disorientation, ataxia, prostration, and seizures, together with fever (>40°C) and hypotension (<80 mm Hg/palpable), are predictive of a nonsurvivable exposure.
      explanation: Clinical description of severe neurovascular involvement.
      directness: DIRECT
      quote_role: REVIEW_SYNTHESIS
  - target: Ataxia
    description: Severe neurovascular injury is associated with this manifestation.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:21986999
      reference_title: Literature review and global consensus on management of acute radiation syndrome affecting nonhematopoietic organ systems.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: Disorientation, ataxia, prostration, and seizures, together with fever (>40°C) and hypotension (<80 mm Hg/palpable), are predictive of a nonsurvivable exposure.
      explanation: Clinical description of severe neurovascular involvement.
      directness: DIRECT
      quote_role: REVIEW_SYNTHESIS
  - target: Seizure
    description: Severe neurovascular injury is associated with this manifestation.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:21986999
      reference_title: Literature review and global consensus on management of acute radiation syndrome affecting nonhematopoietic organ systems.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: Disorientation, ataxia, prostration, and seizures, together with fever (>40°C) and hypotension (<80 mm Hg/palpable), are predictive of a nonsurvivable exposure.
      explanation: Clinical description of severe neurovascular involvement.
      directness: DIRECT
      quote_role: REVIEW_SYNTHESIS
  - target: Hypotension
    description: Severe neurovascular injury is associated with this manifestation.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:21986999
      reference_title: Literature review and global consensus on management of acute radiation syndrome affecting nonhematopoietic organ systems.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: Disorientation, ataxia, prostration, and seizures, together with fever (>40°C) and hypotension (<80 mm Hg/palpable), are predictive of a nonsurvivable exposure.
      explanation: Clinical description of severe neurovascular involvement.
      directness: DIRECT
      quote_role: REVIEW_SYNTHESIS
  - target: Coma
    description: Severe neurovascular injury is associated with this manifestation.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:21986999
      reference_title: Literature review and global consensus on management of acute radiation syndrome affecting nonhematopoietic organ systems.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: A brief latent period lasting several hours typically is followed by severe incapacitation, progressing to coma and death within 24 to 48 hours.
      explanation: Very-high-dose neurovascular illness can progress rapidly after a short latent interval.
      directness: DIRECT
      quote_role: REVIEW_SYNTHESIS
  - target: Cerebral edema
    description: Severe neurovascular injury is associated with this manifestation.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:21986999
      reference_title: Literature review and global consensus on management of acute radiation syndrome affecting nonhematopoietic organ systems.
      supports: SUPPORT
      evidence_source: OTHER
      snippet: Several pathophysiologic processes may contribute to neurovascular collapse, including vascular damage, inflammation, cerebral edema, increased vascular permeability, and perivascular hemorrhage.
      explanation: The consensus presents contributing processes, not a single experimentally resolved human cascade.
      directness: INDIRECT
      quote_role: REVIEW_SYNTHESIS
- name: Radiation-Induced Chromosomal Aberrations
  description: Misrepair of radiation-induced DNA breaks can generate acquired dicentric chromosomes and other aberrations. The dicentric readout supports biological dosimetry; it is not a germline cause of ARS.
  role: consequence
  biological_scale: MOLECULAR
  evidence:
  - reference: PMID:36543843
    reference_title: Dicentric chromosome assay using a deep learning-based automated system.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: Radiation-induced DNA double-strand breaks activate cellular damage repair mechanisms. However, misrepair of chromosomes results in chromosomal aberrations, typically dicentric chromosomes and translocations
    explanation: The assay paper explains the biological basis of the acquired chromosome-damage readout.
    directness: DIRECT
    quote_role: BACKGROUND
phenotypes:
- name: Decreased total lymphocyte count
  description: Early lymphocyte depletion is useful for serial clinical assessment; one count does not define an exact dose.
  phenotype_term:
    preferred_term: Decreased total lymphocyte count
    term:
      id: HP:0001888
      label: Decreased total lymphocyte count
    temporality: ACUTE
  evidence:
  - reference: PMID:21987000
    reference_title: First global consensus for evidence-based management of the hematopoietic syndrome resulting from exposure to ionizing radiation.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: The rate of decline in absolute lymphocyte count correlates closely with dose and dose rate, and has been used as a surrogate marker for whole-body dose.
    explanation: Clinical synthesis supports early lymphocyte depletion as a dose-associated finding.
    directness: DIRECT
    quote_role: REVIEW_SYNTHESIS
- name: Decreased total neutrophil count
  description: Delayed neutropenia increases infection risk.
  phenotype_term:
    preferred_term: Decreased total neutrophil count
    term:
      id: HP:0001875
      label: Decreased total neutrophil count
    temporality: ACUTE
  evidence:
  - reference: url:https://www.fda.gov/emergency-preparedness-and-response/medical-countermeasure-mcm-issues/radiological-and-nuclear-emergency-preparedness
    reference_title: Radiological and Nuclear Emergency Preparedness | FDA
    supports: SUPPORT
    evidence_source: OTHER
    snippet: Severe neutropenia increases the risk of sepsis and death due to infections, while thrombocytopenia increases the risk of hemorrhage and death due to bleeding.
    explanation: FDA describes the distinct infection and bleeding consequences of marrow injury.
    directness: DIRECT
    quote_role: BACKGROUND
- name: Thrombocytopenia
  description: Platelet depletion increases hemorrhage risk.
  phenotype_term:
    preferred_term: Thrombocytopenia
    term:
      id: HP:0001873
      label: Thrombocytopenia
    temporality: ACUTE
  evidence:
  - reference: url:https://www.fda.gov/emergency-preparedness-and-response/medical-countermeasure-mcm-issues/radiological-and-nuclear-emergency-preparedness
    reference_title: Radiological and Nuclear Emergency Preparedness | FDA
    supports: SUPPORT
    evidence_source: OTHER
    snippet: Severe neutropenia increases the risk of sepsis and death due to infections, while thrombocytopenia increases the risk of hemorrhage and death due to bleeding.
    explanation: FDA describes the distinct infection and bleeding consequences of marrow injury.
    directness: DIRECT
    quote_role: BACKGROUND
- name: Anemia
  description: Anemia may develop with prolonged marrow suppression or blood loss.
  phenotype_term:
    preferred_term: Anemia
    term:
      id: HP:0001903
      label: Anemia
    temporality: ACUTE
  evidence:
  - reference: PMID:21987000
    reference_title: First global consensus for evidence-based management of the hematopoietic syndrome resulting from exposure to ionizing radiation.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: Individuals with prolonged anemia, a significant decline in hemoglobin concentration, or both may be candidates for treatment with erythropoietin.
    explanation: The guideline explicitly addresses anemia in radiation-associated marrow injury.
    directness: DIRECT
    quote_role: REVIEW_SYNTHESIS
- name: Pancytopenia
  description: Multiple peripheral lineages can decline over weeks.
  phenotype_term:
    preferred_term: Pancytopenia
    term:
      id: HP:0001876
      label: Pancytopenia
    temporality: ACUTE
  evidence:
  - reference: PMID:21987000
    reference_title: First global consensus for evidence-based management of the hematopoietic syndrome resulting from exposure to ionizing radiation.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Depending on the dose, dose rate, and radiation quality factor, various degrees of pancytopenia develop over several weeks after whole-body or significant partial-body exposure.
    explanation: Clinical synthesis supports dose-dependent cytopenias developing over weeks.
    directness: DIRECT
    quote_role: REVIEW_SYNTHESIS
- name: Bone marrow hypocellularity
  description: Marrow hypocellularity or aplasia reflects severe hematopoietic injury.
  phenotype_term:
    preferred_term: Bone marrow hypocellularity
    term:
      id: HP:0005528
      label: Bone marrow hypocellularity
    temporality: ACUTE
  evidence:
  - reference: PMID:21987000
    reference_title: First global consensus for evidence-based management of the hematopoietic syndrome resulting from exposure to ionizing radiation.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: The primary causes of HS are radiation-induced suppression of mitosis in hematopoietic stem/progenitor cells and their progeny, resulting in hypocellularity and aplasia of the bone marrow and apoptosis in lymphocytes and other hematopoietic cells.
    explanation: The consensus distinguishes impaired marrow production from radiation-induced lymphocyte apoptosis.
    directness: DIRECT
    quote_role: REVIEW_SYNTHESIS
- name: Sepsis
  description: Sepsis may complicate neutropenia and disrupted intestinal barriers.
  phenotype_term:
    preferred_term: Sepsis
    term:
      id: HP:0100806
      label: Sepsis
    temporality: ACUTE
  evidence:
  - reference: url:https://www.fda.gov/emergency-preparedness-and-response/medical-countermeasure-mcm-issues/radiological-and-nuclear-emergency-preparedness
    reference_title: Radiological and Nuclear Emergency Preparedness | FDA
    supports: SUPPORT
    evidence_source: OTHER
    snippet: Severe neutropenia increases the risk of sepsis and death due to infections, while thrombocytopenia increases the risk of hemorrhage and death due to bleeding.
    explanation: FDA describes the distinct infection and bleeding consequences of marrow injury.
    directness: DIRECT
    quote_role: BACKGROUND
- name: Petechiae
  description: Petechiae may accompany thrombocytopenic bleeding.
  phenotype_term:
    preferred_term: Petechiae
    term:
      id: HP:0000967
      label: Petechiae
    temporality: ACUTE
  evidence:
  - reference: PMID:21987000
    reference_title: First global consensus for evidence-based management of the hematopoietic syndrome resulting from exposure to ionizing radiation.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Petechiae, easy bruising, normal hemoglobin level
    explanation: The clinical hematopoietic toxicity table includes petechiae.
    directness: DIRECT
    quote_role: REVIEW_SYNTHESIS
- name: Nausea
  description: Nausea can occur during the prodrome; severity and timing depend on exposure.
  phenotype_term:
    preferred_term: Nausea
    term:
      id: HP:0002018
      label: Nausea
    temporality: ACUTE
  evidence:
  - reference: PMID:21986999
    reference_title: Literature review and global consensus on management of acute radiation syndrome affecting nonhematopoietic organ systems.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Prodromal-phase symptoms include anorexia, nausea, vomiting, and diarrhea.
    explanation: The clinical review describes gastrointestinal symptoms during the prodrome.
    directness: DIRECT
    quote_role: REVIEW_SYNTHESIS
- name: Vomiting
  description: Vomiting can begin early, but neither its presence nor its absence alone determines dose.
  phenotype_term:
    preferred_term: Vomiting
    term:
      id: HP:0002013
      label: Vomiting
    temporality: ACUTE
  evidence:
  - reference: PMID:21986999
    reference_title: Literature review and global consensus on management of acute radiation syndrome affecting nonhematopoietic organ systems.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Prodromal-phase symptoms include anorexia, nausea, vomiting, and diarrhea.
    explanation: The clinical review describes gastrointestinal symptoms during the prodrome.
    directness: DIRECT
    quote_role: REVIEW_SYNTHESIS
- name: Anorexia
  description: Reduced appetite may occur during prodromal and manifest illness.
  phenotype_term:
    preferred_term: Anorexia
    term:
      id: HP:0002039
      label: Anorexia
    temporality: ACUTE
  evidence:
  - reference: PMID:21986999
    reference_title: Literature review and global consensus on management of acute radiation syndrome affecting nonhematopoietic organ systems.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Prodromal-phase symptoms include anorexia, nausea, vomiting, and diarrhea.
    explanation: The clinical review describes gastrointestinal symptoms during the prodrome.
    directness: DIRECT
    quote_role: REVIEW_SYNTHESIS
- name: Diarrhea
  description: Diarrhea can occur during the prodrome and become severe with gastrointestinal injury.
  phenotype_term:
    preferred_term: Diarrhea
    term:
      id: HP:0002014
      label: Diarrhea
    temporality: ACUTE
  evidence:
  - reference: PMID:21986999
    reference_title: Literature review and global consensus on management of acute radiation syndrome affecting nonhematopoietic organ systems.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Prodromal-phase symptoms include anorexia, nausea, vomiting, and diarrhea.
    explanation: The clinical review describes gastrointestinal symptoms during the prodrome.
    directness: DIRECT
    quote_role: REVIEW_SYNTHESIS
  - reference: PMID:21986999
    reference_title: Literature review and global consensus on management of acute radiation syndrome affecting nonhematopoietic organ systems.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: Destruction of the intestinal epithelial lining causes breakdown of the mucosal barrier that normally separates the contents of the intestinal lumen from the GI tissue, resulting in severe secretory diarrhea, dehydration, and electrolyte imbalance.
    explanation: Consensus links epithelial destruction to loss of barrier function and gastrointestinal fluid losses.
    directness: DIRECT
    quote_role: REVIEW_SYNTHESIS
- name: Dehydration
  description: Severe gastrointestinal fluid loss can cause dehydration.
  phenotype_term:
    preferred_term: Dehydration
    term:
      id: HP:0001944
      label: Dehydration
    temporality: ACUTE
  evidence:
  - reference: PMID:21986999
    reference_title: Literature review and global consensus on management of acute radiation syndrome affecting nonhematopoietic organ systems.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: Destruction of the intestinal epithelial lining causes breakdown of the mucosal barrier that normally separates the contents of the intestinal lumen from the GI tissue, resulting in severe secretory diarrhea, dehydration, and electrolyte imbalance.
    explanation: Consensus links epithelial destruction to loss of barrier function and gastrointestinal fluid losses.
    directness: DIRECT
    quote_role: REVIEW_SYNTHESIS
- name: Fever
  description: Fever can occur in manifest illness; high fever is also described with severe neurovascular injury.
  phenotype_term:
    preferred_term: Fever
    term:
      id: HP:0001945
      label: Fever
    temporality: ACUTE
  evidence:
  - reference: PMID:21986999
    reference_title: Literature review and global consensus on management of acute radiation syndrome affecting nonhematopoietic organ systems.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Disorientation, ataxia, prostration, and seizures, together with fever (>40°C) and hypotension (<80 mm Hg/palpable), are predictive of a nonsurvivable exposure.
    explanation: Clinical description of severe neurovascular involvement.
    directness: DIRECT
    quote_role: REVIEW_SYNTHESIS
- name: Malaise
  description: Malaise can occur during the manifest illness stage of hematopoietic and gastrointestinal radiation syndromes.
  phenotype_term:
    preferred_term: Malaise
    term:
      id: HP:0033834
      label: Malaise
    temporality: ACUTE
  evidence:
  - reference: url:https://www.cdc.gov/radiation-emergencies/hcp/clinical-guidance/ars.html
    reference_title: 'Acute Radiation Syndrome: Information for Clinicians | Radiation Emergencies | CDC'
    supports: SUPPORT
    evidence_source: OTHER
    snippet: Symptoms are anorexia, fever, and malaise.
    explanation: CDC lists malaise during manifest hematopoietic radiation illness.
    directness: DIRECT
    quote_role: BACKGROUND
- name: Weight loss
  description: Weight loss is a monitored clinical feature after suspected acute radiation exposure.
  phenotype_term:
    preferred_term: Weight loss
    term:
      id: HP:0001824
      label: Weight loss
    temporality: ACUTE
  evidence:
  - reference: url:https://www.cdc.gov/radiation-emergencies/hcp/clinical-guidance/ars.html
    reference_title: 'Acute Radiation Syndrome: Information for Clinicians | Radiation Emergencies | CDC'
    supports: SUPPORT
    evidence_source: OTHER
    snippet: Careful observation for erythema (document locations), hair loss, skin injury, mucositis, parotitis, weight loss, or fever
    explanation: CDC includes weight loss among findings to watch for during ARS management.
    directness: DIRECT
    quote_role: BACKGROUND
- name: Stomatitis
  description: Mucositis is monitored after suspected acute radiation exposure.
  phenotype_term:
    preferred_term: Stomatitis
    term:
      id: HP:0010280
      label: Stomatitis
    temporality: ACUTE
  evidence:
  - reference: url:https://www.cdc.gov/radiation-emergencies/hcp/clinical-guidance/ars.html
    reference_title: 'Acute Radiation Syndrome: Information for Clinicians | Radiation Emergencies | CDC'
    supports: SUPPORT
    evidence_source: OTHER
    snippet: Careful observation for erythema (document locations), hair loss, skin injury, mucositis, parotitis, weight loss, or fever
    explanation: CDC includes mucositis among findings to watch for during ARS management; HPO represents oral mucositis through Stomatitis.
    directness: DIRECT
    quote_role: BACKGROUND
- name: Erythema
  description: Cutaneous erythema can be transient initially and recur as local injury evolves.
  phenotype_term:
    preferred_term: Erythema
    term:
      id: HP:0010783
      label: Erythema
    temporality: ACUTE
  evidence:
  - reference: url:https://www.cdc.gov/radiation-emergencies/hcp/clinical-guidance/ars.html
    reference_title: 'Acute Radiation Syndrome: Information for Clinicians | Radiation Emergencies | CDC'
    supports: SUPPORT
    evidence_source: OTHER
    snippet: When the basal cell layer of the skin is damaged by radiation, inflammation, erythema, and dry or moist desquamation can occur.
    explanation: CDC links basal epidermal injury to local cutaneous manifestations.
    directness: DIRECT
    quote_role: BACKGROUND
- name: Abnormal blistering of the skin
  description: Blistering can develop after a latent interval following skin irradiation.
  phenotype_term:
    preferred_term: Abnormal blistering of the skin
    term:
      id: HP:0008066
      label: Abnormal blistering of the skin
    temporality: ACUTE
  evidence:
  - reference: url:https://www.cdc.gov/radiation-emergencies/hcp/clinical-guidance/ars.html
    reference_title: 'Acute Radiation Syndrome: Information for Clinicians | Radiation Emergencies | CDC'
    supports: SUPPORT
    evidence_source: OTHER
    snippet: when intense reddening, blistering, and ulceration of the irradiated site are visible.
    explanation: Clinical guidance lists blistering after latent skin injury.
    directness: DIRECT
    quote_role: BACKGROUND
- name: Skin ulcer
  description: Severe local radiation injury can produce ulceration.
  phenotype_term:
    preferred_term: Skin ulcer
    term:
      id: HP:0200042
      label: Skin ulcer
    temporality: ACUTE
  evidence:
  - reference: url:https://www.cdc.gov/radiation-emergencies/hcp/clinical-guidance/ars.html
    reference_title: 'Acute Radiation Syndrome: Information for Clinicians | Radiation Emergencies | CDC'
    supports: SUPPORT
    evidence_source: OTHER
    snippet: when intense reddening, blistering, and ulceration of the irradiated site are visible.
    explanation: Clinical guidance lists skin ulceration.
    directness: DIRECT
    quote_role: BACKGROUND
- name: Alopecia
  description: Hair loss reflects follicular injury at irradiated sites.
  phenotype_term:
    preferred_term: Alopecia
    term:
      id: HP:0001596
      label: Alopecia
    temporality: ACUTE
  evidence:
  - reference: url:https://www.cdc.gov/radiation-emergencies/hcp/clinical-guidance/ars.html
    reference_title: 'Acute Radiation Syndrome: Information for Clinicians | Radiation Emergencies | CDC'
    supports: SUPPORT
    evidence_source: OTHER
    snippet: Also, hair follicles may be damaged, causing epilation.
    explanation: Hair-follicle injury is a separate cause of post-exposure hair loss.
    directness: DIRECT
    quote_role: BACKGROUND
- name: Confusion
  description: Disorientation can occur in severe neurovascular involvement.
  phenotype_term:
    preferred_term: Confusion
    term:
      id: HP:0001289
      label: Confusion
    temporality: ACUTE
  evidence:
  - reference: PMID:21986999
    reference_title: Literature review and global consensus on management of acute radiation syndrome affecting nonhematopoietic organ systems.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Disorientation, ataxia, prostration, and seizures, together with fever (>40°C) and hypotension (<80 mm Hg/palpable), are predictive of a nonsurvivable exposure.
    explanation: Clinical description of severe neurovascular involvement.
    directness: DIRECT
    quote_role: REVIEW_SYNTHESIS
- name: Ataxia
  description: Ataxia is a feature of severe neurovascular injury.
  phenotype_term:
    preferred_term: Ataxia
    term:
      id: HP:0001251
      label: Ataxia
    temporality: ACUTE
  evidence:
  - reference: PMID:21986999
    reference_title: Literature review and global consensus on management of acute radiation syndrome affecting nonhematopoietic organ systems.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Disorientation, ataxia, prostration, and seizures, together with fever (>40°C) and hypotension (<80 mm Hg/palpable), are predictive of a nonsurvivable exposure.
    explanation: Clinical description of severe neurovascular involvement.
    directness: DIRECT
    quote_role: REVIEW_SYNTHESIS
- name: Seizure
  description: Seizures can occur in very-high-dose neurovascular syndrome.
  phenotype_term:
    preferred_term: Seizure
    term:
      id: HP:0001250
      label: Seizure
    temporality: ACUTE
  evidence:
  - reference: PMID:21986999
    reference_title: Literature review and global consensus on management of acute radiation syndrome affecting nonhematopoietic organ systems.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Disorientation, ataxia, prostration, and seizures, together with fever (>40°C) and hypotension (<80 mm Hg/palpable), are predictive of a nonsurvivable exposure.
    explanation: Clinical description of severe neurovascular involvement.
    directness: DIRECT
    quote_role: REVIEW_SYNTHESIS
- name: Hypotension
  description: Hypotension accompanies severe neurovascular collapse and can also result from fluid loss.
  phenotype_term:
    preferred_term: Hypotension
    term:
      id: HP:0002615
      label: Hypotension
    temporality: ACUTE
  evidence:
  - reference: PMID:21986999
    reference_title: Literature review and global consensus on management of acute radiation syndrome affecting nonhematopoietic organ systems.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Disorientation, ataxia, prostration, and seizures, together with fever (>40°C) and hypotension (<80 mm Hg/palpable), are predictive of a nonsurvivable exposure.
    explanation: Clinical description of severe neurovascular involvement.
    directness: DIRECT
    quote_role: REVIEW_SYNTHESIS
- name: Coma
  description: Coma may follow rapid neurovascular deterioration.
  phenotype_term:
    preferred_term: Coma
    term:
      id: HP:0001259
      label: Coma
    temporality: ACUTE
  evidence:
  - reference: PMID:21986999
    reference_title: Literature review and global consensus on management of acute radiation syndrome affecting nonhematopoietic organ systems.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: A brief latent period lasting several hours typically is followed by severe incapacitation, progressing to coma and death within 24 to 48 hours.
    explanation: Very-high-dose neurovascular illness can progress rapidly after a short latent interval.
    directness: DIRECT
    quote_role: REVIEW_SYNTHESIS
- name: Cerebral edema
  description: Cerebral edema is a proposed contributor to neurovascular collapse.
  phenotype_term:
    preferred_term: Cerebral edema
    term:
      id: HP:0002181
      label: Cerebral edema
    temporality: ACUTE
  evidence:
  - reference: PMID:21986999
    reference_title: Literature review and global consensus on management of acute radiation syndrome affecting nonhematopoietic organ systems.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: Several pathophysiologic processes may contribute to neurovascular collapse, including vascular damage, inflammation, cerebral edema, increased vascular permeability, and perivascular hemorrhage.
    explanation: The consensus presents contributing processes, not a single experimentally resolved human cascade.
    directness: INDIRECT
    quote_role: REVIEW_SYNTHESIS
diagnosis:
- name: Dicentric chromosome assay biodosimetry
  description: Dicentric chromosomes in cultured peripheral lymphocytes are scored against a calibrated dose-response curve. This is a reference method for biological dose estimation, with laboratory and throughput constraints. Automated scoring remains method-dependent; the cited DLADES evaluation used healthy donor blood irradiated ex vivo, not an ARS casualty cohort.
  evidence:
  - reference: PMID:36543843
    reference_title: Dicentric chromosome assay using a deep learning-based automated system.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: The dicentric chromosome assay is the "gold standard" in biodosimetry for estimating radiation exposure.
    explanation: Establishes the assay as the reference standard for dose estimation.
  - reference: PMID:36543843
    reference_title: Dicentric chromosome assay using a deep learning-based automated system.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: its large-scale deployment is limited owing to its time-consuming nature and requirement for expert reviewers
    explanation: Records the throughput limitation, which is what makes the faster clinical triage methods below necessary rather than merely convenient.
- name: Lymphocyte depletion kinetics and time to emesis
  description: Serial lymphocyte counts and the interval from exposure to vomiting support early dose assessment. They should be interpreted with exposure history, physical dosimetry, cytogenetics and evolving clinical findings. Vomiting can be absent after a clinically important exposure or occur for other reasons; a single count or symptom should not determine prognosis.
  evidence:
  - reference: PMID:17993851
    reference_title: Estimating radiation dose from time to emesis and lymphocyte depletion.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Lymphocyte depletion kinetics and time to emesis have previously been shown to correlate with radiation dose.
    explanation: Establishes both triage parameters as dose-correlated.
  - reference: PMID:17993851
    reference_title: Estimating radiation dose from time to emesis and lymphocyte depletion.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: dose can be estimated by a simple table lookup, given the ratio of two lymphocyte counts and the time between blood samples.
    explanation: Documents the simplified method, derived from radiation-accident case data, that makes lymphocyte kinetics usable at the bedside.
  - reference: PMID:21986999
    reference_title: Literature review and global consensus on management of acute radiation syndrome affecting nonhematopoietic organ systems.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: Health care providers should base individualized treatment decisions on whatever data are available, especially clinical signs and symptoms, but also take into consideration physical dosimetry and individual biodosimetry.
    explanation: Consensus recommends integrated assessment rather than a symptom-only dose estimate.
    directness: DIRECT
    quote_role: REVIEW_SYNTHESIS
  - reference: PMID:21986999
    reference_title: Literature review and global consensus on management of acute radiation syndrome affecting nonhematopoietic organ systems.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: a false-negative rate of >45% at doses of ≤3 Gy
    explanation: The review documents important false-negative limitations of postexposure vomiting.
    directness: DIRECT
    quote_role: REVIEW_SYNTHESIS
- name: Serial assessment of organ involvement
  description: Assess blood-cell lineages and gastrointestinal, cutaneous and neurologic findings over time, including areas and timing of skin injury. Apparent wellness during a latent interval does not exclude evolving organ damage.
  evidence:
  - reference: url:https://www.cdc.gov/radiation-emergencies/hcp/clinical-guidance/ars.html
    reference_title: 'Acute Radiation Syndrome: Information for Clinicians | Radiation Emergencies | CDC'
    supports: SUPPORT
    evidence_source: OTHER
    snippet: In this stage, the patient looks and feels generally healthy for a few hours or even up to a few weeks.
    explanation: CDC describes the latent stage.
    directness: DIRECT
    quote_role: BACKGROUND
  - reference: url:https://www.cdc.gov/radiation-emergencies/hcp/clinical-guidance/ars.html
    reference_title: 'Acute Radiation Syndrome: Information for Clinicians | Radiation Emergencies | CDC'
    supports: SUPPORT
    evidence_source: OTHER
    snippet: Precisely record all clinical symptoms, particularly nausea, vomiting, diarrhea, and itching, reddening or blistering of the skin. Be sure to include time of onset.
    explanation: Clinical guidance supports serial symptom and skin documentation.
    directness: DIRECT
    quote_role: BACKGROUND
animal_models:
- name: Rhesus macaque filgrastim total-body irradiation study
  species: Macaca mulatta
  description: Randomized blinded study in 46 rhesus macaques given 7.5 Gy total-body LINAC irradiation at 0.8 Gy/min, with medical management in both arms. Filgrastim began 23±3 hours after irradiation; 24 treated animals were compared with 22 controls.
  publication: PMID:23210705
  modeled_mechanisms:
  - target: Bone Marrow Hematopoietic Suppression
    relationship: RECAPITULATES
    fidelity: MODERATE
    description: Reproduces hematopoietic suppression and measures filgrastim-associated survival under this protocol.
    limitations: Controlled total-body irradiation, treatment timing and supportive care differ from heterogeneous accidental exposure. This experiment supports filgrastim; it is not the sole efficacy study for all approved drugs. It does not establish human dose equivalence or gastrointestinal/neurovascular rescue.
    readouts:
    - name: 60-day overall mortality
      target: Bone Marrow Hematopoietic Suppression
      direction: DECREASED
      interpretation: Filgrastim reduced 60-day mortality from 59.1% to 20.8% at an approximate LD 50/60 dose.
      evidence:
      - reference: PMID:23210705
        reference_title: Filgrastim improves survival in lethally irradiated nonhuman primates.
        supports: SUPPORT
        evidence_source: MODEL_ORGANISM
        snippet: Filgrastim significantly (P < 0.004) reduced 60 day overall mortality [20.8% (5/24)] compared to the controls [59.1% (13/22)].
        explanation: The survival readout that carries the efficacy claim for this model.
    evidence:
    - reference: PMID:23210705
      reference_title: Filgrastim improves survival in lethally irradiated nonhuman primates.
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: We evaluated the efficacy of filgrastim to increase survival of nonhuman primates (NHP) exposed to an approximate mid-lethal dose
      explanation: Establishes the model, species and dose regimen this entry's efficacy evidence comes from.
    - reference: PMID:23210705
      reference_title: Filgrastim improves survival in lethally irradiated nonhuman primates.
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: A total of 46 (38 males/8 females) rhesus macaques, Macaca Mulatta, Chinese substrain, 4.0–6.5 kg body weight, were used.
      explanation: Methods establish the number, sex distribution and species of experimental animals.
      directness: DIRECT
      quote_role: PRIMARY_RESULT
  - target: Multilineage Peripheral Cytopenias
    relationship: RECAPITULATES
    fidelity: MODERATE
    description: Reproduces the peripheral cytopenia phase and measures filgrastim's effect on the duration of neutropenia under this protocol.
    limitations: Controlled total-body irradiation, treatment timing and supportive care differ from heterogeneous accidental exposure. Filgrastim shortened the duration of neutropenia without changing the absolute neutrophil count nadir, so this readout does not show that the depth of the cytopenia is rescued, and it does not transfer to other countermeasures.
    readouts:
    - name: Duration of neutropenia
      target: Multilineage Peripheral Cytopenias
      direction: DECREASED
      interpretation: Filgrastim shortened neutropenia in this experiment; the ANC nadir did not differ significantly.
      evidence:
      - reference: PMID:23210705
        reference_title: Filgrastim improves survival in lethally irradiated nonhuman primates.
        supports: SUPPORT
        evidence_source: MODEL_ORGANISM
        snippet: Filgrastim significantly decreased the duration of neutropenia, but did not affect the absolute neutrophil count nadir.
        explanation: The duration-versus-nadir result applies to this regimen and does not define every countermeasure.
        directness: DIRECT
        quote_role: PRIMARY_RESULT
- name: Rhesus macaque pegfilgrastim irradiation study
  species: Macaca mulatta
  description: The FDA label describes a randomized placebo-controlled study with 23 animals per arm, 7.50±0.15 Gy total-body irradiation at 0.8±0.03 Gy/min, pegfilgrastim on days 1 and 8, and medical management including fluids, antibiotics and transfusions.
  publication: url:https://www.accessdata.fda.gov/drugsatfda_docs/label/2015/125031s180lbl.pdf
  modeled_mechanisms:
  - target: Bone Marrow Hematopoietic Suppression
    relationship: PARTIALLY_RECAPITULATES
    fidelity: MODERATE
    description: Models hematopoietic injury and tests an intervention-associated survival outcome.
    limitations: Controlled exposure, species and protocol-defined care limit transfer to human casualties. Survival is an integrated outcome and does not prove rescue of every organ injury.
    evidence:
    - reference: url:https://www.accessdata.fda.gov/drugsatfda_docs/label/2015/125031s180lbl.pdf
      reference_title: https://www.accessdata.fda.gov/drugsatfda_docs/label/2015/125031s180lbl.pdf
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: 91% survival (21/23) in the pegfilgrastim group compared to 48% survival (11/23) in the control group.
      explanation: Pegfilgrastim increased 60-day survival under this two-dose protocol.
      directness: DIRECT
      quote_role: REVIEW_SYNTHESIS
    readouts:
    - name: 60-day survival
      target: Bone Marrow Hematopoietic Suppression
      direction: INCREASED
      interpretation: Pegfilgrastim increased 60-day survival under this two-dose protocol.
      evidence:
      - reference: url:https://www.accessdata.fda.gov/drugsatfda_docs/label/2015/125031s180lbl.pdf
        reference_title: https://www.accessdata.fda.gov/drugsatfda_docs/label/2015/125031s180lbl.pdf
        supports: SUPPORT
        evidence_source: MODEL_ORGANISM
        snippet: 91% survival (21/23) in the pegfilgrastim group compared to 48% survival (11/23) in the control group.
        explanation: Pegfilgrastim increased 60-day survival under this two-dose protocol.
        directness: DIRECT
        quote_role: REVIEW_SYNTHESIS
- name: Rhesus macaque romiplostim irradiation study
  species: Macaca mulatta
  description: The FDA label describes a randomized blinded placebo-controlled study with 40 animals per arm, 6.8 Gy cobalt-60 total-body irradiation, romiplostim 24 hours later and medical management. A combination arm was exploratory.
  publication: url:https://www.accessdata.fda.gov/drugsatfda_docs/label/2021/125268s167lbl.pdf
  modeled_mechanisms:
  - target: Bone Marrow Hematopoietic Suppression
    relationship: PARTIALLY_RECAPITULATES
    fidelity: MODERATE
    description: Models hematopoietic injury and tests an intervention-associated survival outcome.
    limitations: Controlled exposure, species and protocol-defined care limit transfer to human casualties. Survival is an integrated outcome and does not prove rescue of every organ injury.
    evidence:
    - reference: url:https://www.accessdata.fda.gov/drugsatfda_docs/label/2021/125268s167lbl.pdf
      reference_title: https://www.accessdata.fda.gov/drugsatfda_docs/label/2021/125268s167lbl.pdf
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: 72.5% survival (29/40) in the Nplate group compared to 32.5% survival (13/40) in the control group.
      explanation: Romiplostim increased 60-day survival by 40 percentage points in the monotherapy comparison; this is not a human effect estimate.
      directness: DIRECT
      quote_role: REVIEW_SYNTHESIS
    readouts:
    - name: 60-day survival
      target: Bone Marrow Hematopoietic Suppression
      direction: INCREASED
      interpretation: Romiplostim increased 60-day survival by 40 percentage points in the monotherapy comparison; this is not a human effect estimate.
      evidence:
      - reference: url:https://www.accessdata.fda.gov/drugsatfda_docs/label/2021/125268s167lbl.pdf
        reference_title: https://www.accessdata.fda.gov/drugsatfda_docs/label/2021/125268s167lbl.pdf
        supports: SUPPORT
        evidence_source: MODEL_ORGANISM
        snippet: 72.5% survival (29/40) in the Nplate group compared to 32.5% survival (13/40) in the control group.
        explanation: Romiplostim increased 60-day survival by 40 percentage points in the monotherapy comparison; this is not a human effect estimate.
        directness: DIRECT
        quote_role: REVIEW_SYNTHESIS
environmental:
- name: Acute whole-body or substantial partial-body ionizing radiation exposure
  description: A large short-duration dose of penetrating radiation to the whole body or a substantial fraction can produce ARS. Dose distribution can be heterogeneous. Irradiation is distinct from radioactive contamination, which may coexist; chemical absorption-route categories do not describe external irradiation.
  exposure_term:
    preferred_term: acute whole-body or substantial partial-body exposure to ionizing radiation
    term:
      id: ECTO:7000047
      label: exposure to ionizing radiation
  exposure_classifications:
    hazard_agent_type:
    - classification_value: PHYSICAL
    exposure_duration:
    - classification_value: ACUTE
  influences_mechanisms:
  - target: Radiation-Induced DNA Double-Strand Breaks
    environmental_effect: TRIGGERS
    causal_link_type: DIRECT
    description: Radiation exposure induces the DNA double-strand-break response.
    evidence:
    - reference: PMID:24124731
      reference_title: Hematopoietic stem cell injury induced by ionizing radiation.
      supports: SUPPORT
      evidence_source: OTHER
      snippet: IR induces several different types of damage to DNA, which include base damages and changes, cross linking, single-strand breaks, and double-strand breaks (DSBs).
      explanation: This review describes ionizing radiation as an inducer of DNA double-strand breaks.
      directness: DIRECT
      quote_role: REVIEW_SYNTHESIS
  - target: Mature Lymphocyte Apoptosis
    environmental_effect: TRIGGERS
    causal_link_type: DIRECT
    description: Radiation exposure initiates this component of tissue injury.
    evidence:
    - reference: PMID:9525257
      reference_title: Apoptosis induced by fast neutrons versus 60Co gamma-rays in human peripheral blood lymphocytes.
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: The dose-response data confirm the high radiosensitivity of lymphocytes and demonstrate that their response to undergo early interphase cell death by apoptosis is largely independent of LET.
      explanation: Resting human lymphocytes underwent apoptosis after ex-vivo irradiation; cell division is not required.
      directness: DIRECT
      quote_role: PRIMARY_RESULT
  - target: Intestinal Epithelial Injury
    environmental_effect: TRIGGERS
    causal_link_type: DIRECT
    description: Radiation exposure initiates this component of tissue injury.
    evidence:
    - reference: PMID:21986999
      reference_title: Literature review and global consensus on management of acute radiation syndrome affecting nonhematopoietic organ systems.
      supports: SUPPORT
      evidence_source: OTHER
      snippet: Destruction of the intestinal epithelial lining causes breakdown of the mucosal barrier that normally separates the contents of the intestinal lumen from the GI tissue, resulting in severe secretory diarrhea, dehydration, and electrolyte imbalance.
      explanation: Consensus links epithelial destruction to loss of barrier function and gastrointestinal fluid losses.
      directness: DIRECT
      quote_role: REVIEW_SYNTHESIS
  - target: Basal Epidermal Injury
    environmental_effect: TRIGGERS
    causal_link_type: DIRECT
    description: Radiation exposure initiates this component of tissue injury.
    evidence:
    - reference: url:https://www.cdc.gov/radiation-emergencies/hcp/clinical-guidance/ars.html
      reference_title: 'Acute Radiation Syndrome: Information for Clinicians | Radiation Emergencies | CDC'
      supports: SUPPORT
      evidence_source: OTHER
      snippet: When the basal cell layer of the skin is damaged by radiation, inflammation, erythema, and dry or moist desquamation can occur.
      explanation: CDC links basal epidermal injury to local cutaneous manifestations.
      directness: DIRECT
      quote_role: BACKGROUND
  - target: Hair Follicle Injury
    environmental_effect: TRIGGERS
    causal_link_type: DIRECT
    description: Radiation exposure initiates this component of tissue injury.
    evidence:
    - reference: url:https://www.cdc.gov/radiation-emergencies/hcp/clinical-guidance/ars.html
      reference_title: 'Acute Radiation Syndrome: Information for Clinicians | Radiation Emergencies | CDC'
      supports: SUPPORT
      evidence_source: OTHER
      snippet: Also, hair follicles may be damaged, causing epilation.
      explanation: Hair-follicle injury is a separate cause of post-exposure hair loss.
      directness: DIRECT
      quote_role: BACKGROUND
  - target: Neurovascular Injury
    environmental_effect: TRIGGERS
    causal_link_type: DIRECT
    description: Radiation exposure initiates this component of tissue injury.
    evidence:
    - reference: PMID:21986999
      reference_title: Literature review and global consensus on management of acute radiation syndrome affecting nonhematopoietic organ systems.
      supports: SUPPORT
      evidence_source: OTHER
      snippet: Several pathophysiologic processes may contribute to neurovascular collapse, including vascular damage, inflammation, cerebral edema, increased vascular permeability, and perivascular hemorrhage.
      explanation: The consensus presents contributing processes, not a single experimentally resolved human cascade.
      directness: INDIRECT
      quote_role: REVIEW_SYNTHESIS
  notes: The ECTO binding covers ionizing-radiation exposure broadly; the acute duration, penetrating quality and extent are specified in this record. Localized skin injury alone does not establish systemic ARS.
  evidence:
  - reference: url:https://www.cdc.gov/radiation-emergencies/hcp/clinical-guidance/ars.html
    reference_title: 'Acute Radiation Syndrome: Information for Clinicians | Radiation Emergencies | CDC'
    supports: SUPPORT
    evidence_source: OTHER
    snippet: Acute Radiation Syndrome (ARS) (sometimes known as acute radiation sickness) is an acute illness caused by radiation exposure (or irradiation) of the entire body (or most of the body) by a high dose of penetrating radiation in a very short period of time (usually a matter of minutes).
    explanation: Clinical guidance defines the systemic exposure pattern.
    directness: DIRECT
    quote_role: BACKGROUND
treatments:
- name: Filgrastim
  description: Recombinant G-CSF is FDA-approved to improve survival after myelosuppressive radiation exposure. It stimulates residual hematopoiesis. The cited macaque experiment shortened neutropenia without changing its nadir and demonstrated a protocol-specific survival benefit.
  evidence:
  - reference: PMID:23210705
    reference_title: Filgrastim improves survival in lethally irradiated nonhuman primates.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: Filgrastim significantly (P < 0.004) reduced 60 day overall mortality [20.8% (5/24)] compared to the controls [59.1% (13/22)].
    explanation: 'Randomized rhesus study with supportive care: mortality difference was 38.3 percentage points under this protocol.'
    directness: DIRECT
    quote_role: PRIMARY_RESULT
  - reference: PMID:23210705
    reference_title: Filgrastim improves survival in lethally irradiated nonhuman primates.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: Filgrastim significantly decreased the duration of neutropenia, but did not affect the absolute neutrophil count nadir.
    explanation: The duration-versus-nadir result applies to this regimen and does not define every countermeasure.
    directness: DIRECT
    quote_role: PRIMARY_RESULT
  - reference: url:https://www.fda.gov/emergency-preparedness-and-response/medical-countermeasure-mcm-issues/radiological-and-nuclear-emergency-preparedness
    reference_title: Radiological and Nuclear Emergency Preparedness | FDA
    supports: SUPPORT
    evidence_source: OTHER
    snippet: Neupogen (filgrastim) – approved March 2015
    explanation: FDA current preparedness page lists the approved parent product; biosimilars are not separate mechanisms.
    directness: DIRECT
    quote_role: BACKGROUND
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: Filgrastim
      term:
        id: NCIT:C1474
        label: Filgrastim
  target_mechanisms:
  - target: Bone Marrow Hematopoietic Suppression
    treatment_effect: RESTORES
    description: Stimulates recovery of granulopoiesis from surviving progenitors.
    evidence:
    - reference: PMID:23210705
      reference_title: Filgrastim improves survival in lethally irradiated nonhuman primates.
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: Filgrastim significantly (P < 0.004) reduced 60 day overall mortality [20.8% (5/24)] compared to the controls [59.1% (13/22)].
      explanation: 'Randomized rhesus study with supportive care: mortality difference was 38.3 percentage points under this protocol.'
      directness: DIRECT
      quote_role: PRIMARY_RESULT
    - reference: PMID:23210705
      reference_title: Filgrastim improves survival in lethally irradiated nonhuman primates.
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: Filgrastim significantly decreased the duration of neutropenia, but did not affect the absolute neutrophil count nadir.
      explanation: The duration-versus-nadir result applies to this regimen and does not define every countermeasure.
      directness: DIRECT
      quote_role: PRIMARY_RESULT
    - reference: url:https://www.fda.gov/emergency-preparedness-and-response/medical-countermeasure-mcm-issues/radiological-and-nuclear-emergency-preparedness
      reference_title: Radiological and Nuclear Emergency Preparedness | FDA
      supports: SUPPORT
      evidence_source: OTHER
      snippet: Neupogen (filgrastim) – approved March 2015
      explanation: FDA current preparedness page lists the approved parent product; biosimilars are not separate mechanisms.
      directness: DIRECT
      quote_role: BACKGROUND
  therapeutic_modality: OTHER
- name: Pegfilgrastim
  description: Pegylated G-CSF is another FDA-approved hematopoietic countermeasure. Its animal efficacy study used a separate two-dose regimen and does not establish a gastrointestinal or neurovascular treatment effect.
  evidence:
  - reference: url:https://www.accessdata.fda.gov/drugsatfda_docs/label/2015/125031s180lbl.pdf
    reference_title: https://www.accessdata.fda.gov/drugsatfda_docs/label/2015/125031s180lbl.pdf
    supports: SUPPORT
    evidence_source: OTHER
    snippet: Pegfilgrastim is a colony-stimulating factor that acts on hematopoietic cells by binding to specific cell surface receptors, thereby stimulating proliferation, differentiation, commitment, and end cell functional activation.
    explanation: FDA label explains colony-stimulating activity.
    directness: DIRECT
    quote_role: BACKGROUND
  - reference: url:https://www.fda.gov/emergency-preparedness-and-response/medical-countermeasure-mcm-issues/radiological-and-nuclear-emergency-preparedness
    reference_title: Radiological and Nuclear Emergency Preparedness | FDA
    supports: SUPPORT
    evidence_source: OTHER
    snippet: Neulasta (pegfilgrastim) – approved November 2015
    explanation: FDA current preparedness page lists the approved parent product; biosimilars are not separate mechanisms.
    directness: DIRECT
    quote_role: BACKGROUND
  - reference: url:https://www.accessdata.fda.gov/drugsatfda_docs/label/2015/125031s180lbl.pdf
    reference_title: https://www.accessdata.fda.gov/drugsatfda_docs/label/2015/125031s180lbl.pdf
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: 91% survival (21/23) in the pegfilgrastim group compared to 48% survival (11/23) in the control group.
    explanation: This separate randomized rhesus study used treatment on days 1 and 8 plus medical management; it is not the filgrastim trial.
    directness: DIRECT
    quote_role: REVIEW_SYNTHESIS
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: Pegfilgrastim
      term:
        id: NCIT:C1854
        label: Pegfilgrastim
  target_mechanisms:
  - target: Bone Marrow Hematopoietic Suppression
    treatment_effect: RESTORES
    description: Promotes recovery of hematopoietic cell production.
    evidence:
    - reference: url:https://www.accessdata.fda.gov/drugsatfda_docs/label/2015/125031s180lbl.pdf
      reference_title: https://www.accessdata.fda.gov/drugsatfda_docs/label/2015/125031s180lbl.pdf
      supports: SUPPORT
      evidence_source: OTHER
      snippet: Pegfilgrastim is a colony-stimulating factor that acts on hematopoietic cells by binding to specific cell surface receptors, thereby stimulating proliferation, differentiation, commitment, and end cell functional activation.
      explanation: FDA label explains colony-stimulating activity.
      directness: DIRECT
      quote_role: BACKGROUND
    - reference: url:https://www.fda.gov/emergency-preparedness-and-response/medical-countermeasure-mcm-issues/radiological-and-nuclear-emergency-preparedness
      reference_title: Radiological and Nuclear Emergency Preparedness | FDA
      supports: SUPPORT
      evidence_source: OTHER
      snippet: Neulasta (pegfilgrastim) – approved November 2015
      explanation: FDA current preparedness page lists the approved parent product; biosimilars are not separate mechanisms.
      directness: DIRECT
      quote_role: BACKGROUND
    - reference: url:https://www.accessdata.fda.gov/drugsatfda_docs/label/2015/125031s180lbl.pdf
      reference_title: https://www.accessdata.fda.gov/drugsatfda_docs/label/2015/125031s180lbl.pdf
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: 91% survival (21/23) in the pegfilgrastim group compared to 48% survival (11/23) in the control group.
      explanation: This separate randomized rhesus study used treatment on days 1 and 8 plus medical management; it is not the filgrastim trial.
      directness: DIRECT
      quote_role: REVIEW_SYNTHESIS
  therapeutic_modality: OTHER
- name: Sargramostim
  description: Recombinant GM-CSF is FDA-approved for hematopoietic ARS and stimulates surviving myeloid progenitors. Human accident reports of colony-stimulating factors are uncontrolled and do not supply a precise drug-specific survival effect.
  evidence:
  - reference: PMID:34402734
    reference_title: 'Radiation countermeasures for hematopoietic acute radiation syndrome: growth factors, cytokines and beyond.'
    supports: SUPPORT
    evidence_source: OTHER
    snippet: These agents are largely recombinant growth factors (e.g. rhuG-CSF/filgrastim, rhuGM-CSF/sargramostim) that target and stimulate myeloid progenitors within bone marrow.
    explanation: Review identifies sargramostim and its marrow progenitor target.
    directness: DIRECT
    quote_role: REVIEW_SYNTHESIS
  - reference: url:https://www.fda.gov/emergency-preparedness-and-response/medical-countermeasure-mcm-issues/radiological-and-nuclear-emergency-preparedness
    reference_title: Radiological and Nuclear Emergency Preparedness | FDA
    supports: SUPPORT
    evidence_source: OTHER
    snippet: Leukine (sargramostim) – approved March 29, 2018
    explanation: FDA current preparedness page lists the approved parent product; biosimilars are not separate mechanisms.
    directness: DIRECT
    quote_role: BACKGROUND
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: Sargramostim
      term:
        id: NCIT:C1492
        label: Sargramostim
  target_mechanisms:
  - target: Bone Marrow Hematopoietic Suppression
    treatment_effect: RESTORES
    description: Stimulates recovery of myeloid hematopoiesis.
    evidence:
    - reference: PMID:34402734
      reference_title: 'Radiation countermeasures for hematopoietic acute radiation syndrome: growth factors, cytokines and beyond.'
      supports: SUPPORT
      evidence_source: OTHER
      snippet: These agents are largely recombinant growth factors (e.g. rhuG-CSF/filgrastim, rhuGM-CSF/sargramostim) that target and stimulate myeloid progenitors within bone marrow.
      explanation: Review identifies sargramostim and its marrow progenitor target.
      directness: DIRECT
      quote_role: REVIEW_SYNTHESIS
    - reference: url:https://www.fda.gov/emergency-preparedness-and-response/medical-countermeasure-mcm-issues/radiological-and-nuclear-emergency-preparedness
      reference_title: Radiological and Nuclear Emergency Preparedness | FDA
      supports: SUPPORT
      evidence_source: OTHER
      snippet: Leukine (sargramostim) – approved March 29, 2018
      explanation: FDA current preparedness page lists the approved parent product; biosimilars are not separate mechanisms.
      directness: DIRECT
      quote_role: BACKGROUND
  therapeutic_modality: OTHER
- name: Romiplostim
  description: The FDA-approved thrombopoietin-receptor agonist is an Fc-peptide fusion protein that increases platelet production. Regulatory efficacy rests on animal studies, with supportive human pharmacodynamic and safety information from other settings.
  evidence:
  - reference: url:https://www.accessdata.fda.gov/drugsatfda_docs/label/2021/125268s167lbl.pdf
    reference_title: https://www.accessdata.fda.gov/drugsatfda_docs/label/2021/125268s167lbl.pdf
    supports: SUPPORT
    evidence_source: OTHER
    snippet: Romiplostim is a thrombopoietin receptor agonist (TPO-RA). Romiplostim, a member of the TPO mimetic class, is an Fc-peptide fusion protein (peptibody).
    explanation: Romiplostim is a biologic peptibody, not a small molecule.
    directness: DIRECT
    quote_role: BACKGROUND
  - reference: url:https://www.accessdata.fda.gov/drugsatfda_docs/label/2021/125268s167lbl.pdf
    reference_title: https://www.accessdata.fda.gov/drugsatfda_docs/label/2021/125268s167lbl.pdf
    supports: SUPPORT
    evidence_source: OTHER
    snippet: Nplate increases platelet production through binding and activation of the TPO receptor, a mechanism analogous to endogenous TPO.
    explanation: FDA label supports the platelet-production mechanism.
    directness: DIRECT
    quote_role: BACKGROUND
  - reference: url:https://www.accessdata.fda.gov/drugsatfda_docs/label/2021/125268s167lbl.pdf
    reference_title: https://www.accessdata.fda.gov/drugsatfda_docs/label/2021/125268s167lbl.pdf
    supports: SUPPORT
    evidence_source: OTHER
    snippet: Nplate is indicated to increase survival in adults and in pediatric patients (including term neonates) acutely exposed to myelosuppressive doses of radiation
    explanation: FDA label states the hematopoietic ARS indication.
    directness: DIRECT
    quote_role: BACKGROUND
  - reference: url:https://www.accessdata.fda.gov/drugsatfda_docs/label/2021/125268s167lbl.pdf
    reference_title: https://www.accessdata.fda.gov/drugsatfda_docs/label/2021/125268s167lbl.pdf
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: 72.5% survival (29/40) in the Nplate group compared to 32.5% survival (13/40) in the control group.
    explanation: Randomized blinded rhesus efficacy study under 6.8 Gy total-body irradiation and medical management.
    directness: DIRECT
    quote_role: REVIEW_SYNTHESIS
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: Romiplostim
      term:
        id: NCIT:C52183
        label: Romiplostim
  target_mechanisms:
  - target: Thrombocytopenia
    treatment_effect: INHIBITS
    description: Increases platelet production through activation of the TPO receptor.
    evidence:
    - reference: url:https://www.accessdata.fda.gov/drugsatfda_docs/label/2021/125268s167lbl.pdf
      reference_title: https://www.accessdata.fda.gov/drugsatfda_docs/label/2021/125268s167lbl.pdf
      supports: SUPPORT
      evidence_source: OTHER
      snippet: Romiplostim is a thrombopoietin receptor agonist (TPO-RA). Romiplostim, a member of the TPO mimetic class, is an Fc-peptide fusion protein (peptibody).
      explanation: Romiplostim is a biologic peptibody, not a small molecule.
      directness: DIRECT
      quote_role: BACKGROUND
    - reference: url:https://www.accessdata.fda.gov/drugsatfda_docs/label/2021/125268s167lbl.pdf
      reference_title: https://www.accessdata.fda.gov/drugsatfda_docs/label/2021/125268s167lbl.pdf
      supports: SUPPORT
      evidence_source: OTHER
      snippet: Nplate increases platelet production through binding and activation of the TPO receptor, a mechanism analogous to endogenous TPO.
      explanation: FDA label supports the platelet-production mechanism.
      directness: DIRECT
      quote_role: BACKGROUND
    - reference: url:https://www.accessdata.fda.gov/drugsatfda_docs/label/2021/125268s167lbl.pdf
      reference_title: https://www.accessdata.fda.gov/drugsatfda_docs/label/2021/125268s167lbl.pdf
      supports: SUPPORT
      evidence_source: OTHER
      snippet: Nplate is indicated to increase survival in adults and in pediatric patients (including term neonates) acutely exposed to myelosuppressive doses of radiation
      explanation: FDA label states the hematopoietic ARS indication.
      directness: DIRECT
      quote_role: BACKGROUND
    - reference: url:https://www.accessdata.fda.gov/drugsatfda_docs/label/2021/125268s167lbl.pdf
      reference_title: https://www.accessdata.fda.gov/drugsatfda_docs/label/2021/125268s167lbl.pdf
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: 72.5% survival (29/40) in the Nplate group compared to 32.5% survival (13/40) in the control group.
      explanation: Randomized blinded rhesus efficacy study under 6.8 Gy total-body irradiation and medical management.
      directness: DIRECT
      quote_role: REVIEW_SYNTHESIS
  therapeutic_modality: OTHER
- name: Erythropoiesis-stimulating agents for prolonged anemia
  description: The 2011 consensus weakly recommends considering erythropoietin in selected patients with prolonged anemia or a significant hemoglobin decline. Response takes weeks. Use requires individualized assessment of risks, iron status and applicable product labeling; this recommendation does not establish controlled human ARS efficacy or an FDA ARS indication.
  evidence:
  - reference: PMID:21987000
    reference_title: First global consensus for evidence-based management of the hematopoietic syndrome resulting from exposure to ionizing radiation.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: Individuals with prolonged anemia, a significant decline in hemoglobin concentration, or both may be candidates for treatment with erythropoietin.
    explanation: The 2011 consensus makes a weak recommendation for selected prolonged anemia; this is not controlled human ARS efficacy.
    directness: DIRECT
    quote_role: REVIEW_SYNTHESIS
  - reference: PMID:21987000
    reference_title: First global consensus for evidence-based management of the hematopoietic syndrome resulting from exposure to ionizing radiation.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: Experiencing a response to erythropoietin will take weeks rather than days.
    explanation: The expected response is delayed and does not replace urgent transfusion support.
    directness: DIRECT
    quote_role: REVIEW_SYNTHESIS
  - reference: PMID:21987000
    reference_title: First global consensus for evidence-based management of the hematopoietic syndrome resulting from exposure to ionizing radiation.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: Strong caveats recommending specific indications for the use of ESAs are incorporated in a “black box” warning by the US Food and Drug Administration (FDA).
    explanation: The consensus emphasizes regulatory safety constraints and individualized selection.
    directness: DIRECT
    quote_role: REVIEW_SYNTHESIS
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: Recombinant Erythropoietin
      term:
        id: NCIT:C477
        label: Recombinant Erythropoietin
  target_mechanisms:
  - target: Anemia
    treatment_effect: INHIBITS
    description: Stimulates erythrocyte production in selected patients with prolonged anemia.
    evidence:
    - reference: PMID:21987000
      reference_title: First global consensus for evidence-based management of the hematopoietic syndrome resulting from exposure to ionizing radiation.
      supports: SUPPORT
      evidence_source: OTHER
      snippet: Individuals with prolonged anemia, a significant decline in hemoglobin concentration, or both may be candidates for treatment with erythropoietin.
      explanation: The 2011 consensus makes a weak recommendation for selected prolonged anemia; this is not controlled human ARS efficacy.
      directness: DIRECT
      quote_role: REVIEW_SYNTHESIS
    - reference: PMID:21987000
      reference_title: First global consensus for evidence-based management of the hematopoietic syndrome resulting from exposure to ionizing radiation.
      supports: SUPPORT
      evidence_source: OTHER
      snippet: Experiencing a response to erythropoietin will take weeks rather than days.
      explanation: The expected response is delayed and does not replace urgent transfusion support.
      directness: DIRECT
      quote_role: REVIEW_SYNTHESIS
    - reference: PMID:21987000
      reference_title: First global consensus for evidence-based management of the hematopoietic syndrome resulting from exposure to ionizing radiation.
      supports: SUPPORT
      evidence_source: OTHER
      snippet: Strong caveats recommending specific indications for the use of ESAs are incorporated in a “black box” warning by the US Food and Drug Administration (FDA).
      explanation: The consensus emphasizes regulatory safety constraints and individualized selection.
      directness: DIRECT
      quote_role: REVIEW_SYNTHESIS
  therapeutic_modality: OTHER
- name: Antimicrobial prophylaxis and infection treatment
  description: Infection prevention and prompt treatment are central during neutropenia. Antibacterial, antifungal and antiviral choices depend on clinical findings, cultures, local resistance and patient factors; the evidence for specific gastrointestinal prophylaxis strategies is limited.
  evidence:
  - reference: PMID:21986999
    reference_title: Literature review and global consensus on management of acute radiation syndrome affecting nonhematopoietic organ systems.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: Patients with suspected or established infection should be placed on a treatment regimen that is similar to that of patients with malignancy and neutropenic sepsis.
    explanation: Consensus supports management of neutropenic infection.
    directness: DIRECT
    quote_role: REVIEW_SYNTHESIS
  treatment_term:
    preferred_term: Antibiotic Therapy
    term:
      id: NCIT:C15620
      label: Antibiotic Therapy
  target_mechanisms:
  - target: Sepsis
    treatment_effect: INHIBITS
    description: Antimicrobial treatment addresses infection complicating immune and barrier injury.
    evidence:
    - reference: PMID:21986999
      reference_title: Literature review and global consensus on management of acute radiation syndrome affecting nonhematopoietic organ systems.
      supports: SUPPORT
      evidence_source: OTHER
      snippet: Patients with suspected or established infection should be placed on a treatment regimen that is similar to that of patients with malignancy and neutropenic sepsis.
      explanation: Consensus supports management of neutropenic infection.
      directness: DIRECT
      quote_role: REVIEW_SYNTHESIS
- name: Fluid and electrolyte replacement
  description: Replace losses from vomiting and diarrhea and support intravascular volume according to clinical and laboratory assessment.
  evidence:
  - reference: PMID:21986999
    reference_title: Literature review and global consensus on management of acute radiation syndrome affecting nonhematopoietic organ systems.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: Hospitalized patients should be provided with electrolyte and fluid replacement.
    explanation: Consensus recommends fluid/electrolyte support.
    directness: DIRECT
    quote_role: REVIEW_SYNTHESIS
  treatment_term:
    preferred_term: Fluid Therapy
    term:
      id: NCIT:C116537
      label: Fluid Therapy
  target_mechanisms:
  - target: Dehydration
    treatment_effect: INHIBITS
    description: Replenishes lost fluid and electrolytes.
    evidence:
    - reference: PMID:21986999
      reference_title: Literature review and global consensus on management of acute radiation syndrome affecting nonhematopoietic organ systems.
      supports: SUPPORT
      evidence_source: OTHER
      snippet: Hospitalized patients should be provided with electrolyte and fluid replacement.
      explanation: Consensus recommends fluid/electrolyte support.
      directness: DIRECT
      quote_role: REVIEW_SYNTHESIS
- name: Antiemetic therapy
  description: Serotonin-receptor antagonists are recommended for radiation-associated nausea and vomiting. This is symptom control, not reversal of the initial radiation injury.
  evidence:
  - reference: PMID:21986999
    reference_title: Literature review and global consensus on management of acute radiation syndrome affecting nonhematopoietic organ systems.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: The antiemetic of choice is a serotonin-receptor antagonist
    explanation: Consensus identifies this class as preferred antiemetic support.
    directness: DIRECT
    quote_role: REVIEW_SYNTHESIS
  treatment_term:
    preferred_term: Nausea and Vomiting Therapy
    term:
      id: NCIT:C15473
      label: Nausea and Vomiting Therapy
  target_mechanisms:
  - target: Vomiting
    treatment_effect: INHIBITS
    description: Reduces emesis and associated fluid loss.
    evidence:
    - reference: PMID:21986999
      reference_title: Literature review and global consensus on management of acute radiation syndrome affecting nonhematopoietic organ systems.
      supports: SUPPORT
      evidence_source: OTHER
      snippet: The antiemetic of choice is a serotonin-receptor antagonist
      explanation: Consensus identifies this class as preferred antiemetic support.
      directness: DIRECT
      quote_role: REVIEW_SYNTHESIS
- name: Antidiarrheal therapy
  description: Loperamide is a recommended symptomatic option for diarrhea. The consensus recommendation is weak and does not establish reversal of mucosal injury.
  evidence:
  - reference: PMID:21986999
    reference_title: Literature review and global consensus on management of acute radiation syndrome affecting nonhematopoietic organ systems.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: Administer loperamide pro re nata for control of diarrhea
    explanation: Consensus table recommends symptomatic diarrhea control.
    directness: DIRECT
    quote_role: REVIEW_SYNTHESIS
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: loperamide
      term:
        id: CHEBI:6532
        label: loperamide
  target_mechanisms:
  - target: Diarrhea
    treatment_effect: INHIBITS
    description: Reduces the diarrheal symptom burden.
    evidence:
    - reference: PMID:21986999
      reference_title: Literature review and global consensus on management of acute radiation syndrome affecting nonhematopoietic organ systems.
      supports: SUPPORT
      evidence_source: OTHER
      snippet: Administer loperamide pro re nata for control of diarrhea
      explanation: Consensus table recommends symptomatic diarrhea control.
      directness: DIRECT
      quote_role: REVIEW_SYNTHESIS
- name: Nutritional support
  description: Enteral support is preferred when feasible; parenteral support may be required when ileus or diffuse gastrointestinal mucosal bleeding prevents its use.
  evidence:
  - reference: PMID:21986999
    reference_title: Literature review and global consensus on management of acute radiation syndrome affecting nonhematopoietic organ systems.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: parenteral support is indicated in patients with adynamic ileus or diffuse bleeding from the GI mucosa.
    explanation: The full consensus text supplies the exception to enteral support.
    directness: DIRECT
    quote_role: REVIEW_SYNTHESIS
  - reference: PMID:21986999
    reference_title: Literature review and global consensus on management of acute radiation syndrome affecting nonhematopoietic organ systems.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: Oral nutritional support is preferred over parenteral nutrition because it promotes the immunological and physiological integrity of the GI tract
    explanation: Consensus supports enteral nutrition when feasible.
    directness: DIRECT
    quote_role: REVIEW_SYNTHESIS
  treatment_term:
    preferred_term: Nutritional Support
    term:
      id: NCIT:C15433
      label: Nutritional Support
- name: Transfusion support
  description: Platelet transfusion may be required for severe thrombocytopenia. Blood-product support is supportive treatment and does not demonstrate restored endogenous marrow production.
  evidence:
  - reference: url:https://www.cdc.gov/radiation-emergencies/hcp/clinical-guidance/ars.html
    reference_title: 'Acute Radiation Syndrome: Information for Clinicians | Radiation Emergencies | CDC'
    supports: SUPPORT
    evidence_source: OTHER
    snippet: Stem cell transplantation or platelet transfusions (if platelet count is too low)
    explanation: CDC lists platelet transfusion among indicated support measures.
    directness: DIRECT
    quote_role: REVIEW_SYNTHESIS
  treatment_term:
    preferred_term: Platelet Transfusion
    term:
      id: NCIT:C15366
      label: Platelet Transfusion
  target_mechanisms:
  - target: Thrombocytopenia
    treatment_effect: BYPASSES
    description: Supplies platelets while endogenous production is impaired.
    evidence:
    - reference: url:https://www.cdc.gov/radiation-emergencies/hcp/clinical-guidance/ars.html
      reference_title: 'Acute Radiation Syndrome: Information for Clinicians | Radiation Emergencies | CDC'
      supports: SUPPORT
      evidence_source: OTHER
      snippet: Stem cell transplantation or platelet transfusions (if platelet count is too low)
      explanation: CDC lists platelet transfusion among indicated support measures.
      directness: DIRECT
      quote_role: REVIEW_SYNTHESIS
- name: Selective hematopoietic stem-cell transplantation
  description: Consider transplantation only for persistent marrow aplasia without spontaneous recovery or response after 2–3 weeks of cytokine treatment and without significant nonhematopoietic organ injury. The consensus recommendation is weak; historical uncontrolled outcomes do not establish benefit from routine early transplantation.
  evidence:
  - reference: PMID:21987000
    reference_title: First global consensus for evidence-based management of the hematopoietic syndrome resulting from exposure to ionizing radiation.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: Stem/progenitor cell replacement therapy should not be administered until there is a documented lack of spontaneous recovery and/or lack of response following 2 to 3 weeks of cytokine treatment.
    explanation: Consensus restricts timing and patient selection.
    directness: DIRECT
    quote_role: REVIEW_SYNTHESIS
  - reference: PMID:21987000
    reference_title: First global consensus for evidence-based management of the hematopoietic syndrome resulting from exposure to ionizing radiation.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: it has been recommended that hematopoietic stem/progenitor cell therapy not be used for patients with aplasia and significant injury to another organ system.
    explanation: Nonhematopoietic organ injury limits transplantation candidacy.
    directness: DIRECT
    quote_role: REVIEW_SYNTHESIS
  treatment_term:
    preferred_term: Hematopoietic Cell Transplantation
    term:
      id: NCIT:C15431
      label: Hematopoietic Cell Transplantation
  target_mechanisms:
  - target: Bone Marrow Hematopoietic Suppression
    treatment_effect: RESTORES
    description: Provides hematopoietic progenitors in selected patients with persistent marrow failure.
    evidence:
    - reference: PMID:21987000
      reference_title: First global consensus for evidence-based management of the hematopoietic syndrome resulting from exposure to ionizing radiation.
      supports: SUPPORT
      evidence_source: OTHER
      snippet: Stem/progenitor cell replacement therapy should not be administered until there is a documented lack of spontaneous recovery and/or lack of response following 2 to 3 weeks of cytokine treatment.
      explanation: Consensus restricts timing and patient selection.
      directness: DIRECT
      quote_role: REVIEW_SYNTHESIS
    - reference: PMID:21987000
      reference_title: First global consensus for evidence-based management of the hematopoietic syndrome resulting from exposure to ionizing radiation.
      supports: SUPPORT
      evidence_source: OTHER
      snippet: it has been recommended that hematopoietic stem/progenitor cell therapy not be used for patients with aplasia and significant injury to another organ system.
      explanation: Nonhematopoietic organ injury limits transplantation candidacy.
      directness: DIRECT
      quote_role: REVIEW_SYNTHESIS
- name: Topical treatment of cutaneous radiation injury
  description: Specialist local care can include topical corticosteroids, antibiotics and antihistamines. Systemic corticosteroids are not routine therapy without a specific indication.
  evidence:
  - reference: PMID:21986999
    reference_title: Literature review and global consensus on management of acute radiation syndrome affecting nonhematopoietic organ systems.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: Anti-inflammatory agents such as topical class II to III steroids (eg, betamethasone, mometasone), topical antibiotics, and antihistamines should be considered.
    explanation: Consensus describes topical management of radiation skin injury.
    directness: DIRECT
    quote_role: REVIEW_SYNTHESIS
  treatment_term:
    preferred_term: Wound Care Management
    term:
      id: NCIT:C116681
      label: Wound Care Management
  target_mechanisms:
  - target: Erythema
    treatment_effect: INHIBITS
    description: Topical anti-inflammatory care reduces cutaneous inflammation.
    evidence:
    - reference: PMID:21986999
      reference_title: Literature review and global consensus on management of acute radiation syndrome affecting nonhematopoietic organ systems.
      supports: SUPPORT
      evidence_source: OTHER
      snippet: Anti-inflammatory agents such as topical class II to III steroids (eg, betamethasone, mometasone), topical antibiotics, and antihistamines should be considered.
      explanation: Consensus describes topical management of radiation skin injury.
      directness: DIRECT
      quote_role: REVIEW_SYNTHESIS
- name: Excision and grafting for severe skin injury
  description: Surgical excision and grafting may be required for radiation ulcers, localized necrosis or severe intractable pain, with specialist assessment of injury extent.
  evidence:
  - reference: PMID:21986999
    reference_title: Literature review and global consensus on management of acute radiation syndrome affecting nonhematopoietic organ systems.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: Ulcers, localized necrosis, and severe intractable pain are best treated by surgical excision and skin grafts.
    explanation: Consensus specifies circumstances for surgery.
    directness: DIRECT
    quote_role: REVIEW_SYNTHESIS
  treatment_term:
    preferred_term: Skin Transplantation
    term:
      id: NCIT:C15325
      label: Skin Transplantation
  target_mechanisms:
  - target: Skin ulcer
    treatment_effect: BYPASSES
    description: Resects severely injured tissue and replaces lost skin coverage.
    evidence:
    - reference: PMID:21986999
      reference_title: Literature review and global consensus on management of acute radiation syndrome affecting nonhematopoietic organ systems.
      supports: SUPPORT
      evidence_source: OTHER
      snippet: Ulcers, localized necrosis, and severe intractable pain are best treated by surgical excision and skin grafts.
      explanation: Consensus specifies circumstances for surgery.
      directness: DIRECT
      quote_role: REVIEW_SYNTHESIS
- name: Neurovascular supportive and palliative care
  description: Provide symptom relief, seizure management and appropriate supportive or palliative care for severe neurovascular syndrome. Such care does not imply established reversal of nonsurvivable radiation injury.
  evidence:
  - reference: PMID:21986999
    reference_title: Literature review and global consensus on management of acute radiation syndrome affecting nonhematopoietic organ systems.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: At present, supportive care alone is recommended for patients diagnosed as having the neurovascular syndrome.
    explanation: Consensus emphasizes supportive care rather than proven organ rescue.
    directness: DIRECT
    quote_role: REVIEW_SYNTHESIS
  treatment_term:
    preferred_term: Palliative Therapy
    term:
      id: NCIT:C15292
      label: Palliative Therapy
- name: Intensive care organ support
  description: Severe multisystem injury may require intensive care, including lung-protective mechanical ventilation for acute respiratory failure and individualized hemodynamic or renal support. These are supportive-care recommendations extrapolated in part from other critical illnesses, not demonstrated reversal of radiation damage.
  evidence:
  - reference: PMID:21986999
    reference_title: Literature review and global consensus on management of acute radiation syndrome affecting nonhematopoietic organ systems.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: Administer mechanical ventilation with a lung-protective strategy for acute respiratory failure
    explanation: The consensus table gives a strong recommendation for supportive ventilation.
    directness: DIRECT
    quote_role: REVIEW_SYNTHESIS
  - reference: PMID:21986999
    reference_title: Literature review and global consensus on management of acute radiation syndrome affecting nonhematopoietic organ systems.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: hemodialysis for patients with significant renal impairment.
    explanation: The 2011 consensus identifies renal replacement as possible supportive care; no ARS-specific efficacy estimate is supplied.
    directness: DIRECT
    quote_role: REVIEW_SYNTHESIS
  treatment_term:
    preferred_term: Supportive Care
    term:
      id: NCIT:C15747
      label: Supportive Care
- name: Psychological support
  description: Provide psychological support for exposed patients and families alongside physical care.
  evidence:
  - reference: PMID:21986999
    reference_title: Literature review and global consensus on management of acute radiation syndrome affecting nonhematopoietic organ systems.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: every attempt should be made to provide psychological support, sedatives, and anxiolytics, as necessary.
    explanation: Consensus includes psychological support alongside medical management.
    directness: DIRECT
    quote_role: REVIEW_SYNTHESIS
  treatment_term:
    preferred_term: Supportive Care
    term:
      id: NCIT:C15747
      label: Supportive Care
- name: HemaMax (investigational recombinant human IL-12)
  description: HemaMax has completed registered Phase I and Phase II healthy-volunteer safety/pharmacology studies for countermeasure development. These studies do not establish efficacy against ARS in irradiated people.
  evidence:
  - reference: clinicaltrials:NCT01742221
    reference_title: A Phase 1b, Single-Dose, Randomized, Double-Blind, Placebo-Controlled Study to Evaluate the Safety, Tolerability, Pharmacokinetics, and Pharmacodynamics of HemaMax™ (rHuIL-12) in Healthy Subjects
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: This trial is designed to evaluate the safety, pharmacokinetics, and pharmacodynamics of HemaMax in healthy male and female volunteers.
    explanation: Registry description establishes the study purpose and population; it is not an efficacy result.
    directness: DIRECT
  - reference: clinicaltrials:NCT02343133
    reference_title: A Phase 2 Single-Dose, Randomized, Double-Blind, Placebo-Controlled Study to Evaluate the Safety, Tolerability, Pharmacokinetics, and Pharmacodynamics of HemaMax™ (rHuIL-12) in Healthy Subjects
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: The purpose of this study is to determine whether HemaMax is safe and well tolerated to support efficacy under FDA's Animal Rule to reduce the morbidity and mortality associated with the hematopoietic syndrome of acute radiation syndrome.
    explanation: Registry description establishes the study purpose and population; it is not an efficacy result.
    directness: DIRECT
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: recombinant human interleukin-12 (HemaMax)
  therapeutic_modality: OTHER
discussions:
- discussion_id: ars_animal_rule_evidence_base
  kind: HUMAN_MODEL_MISMATCH
  status: OPEN
  prompt: How do exposure heterogeneity, combined injury and available supportive care modify the benefit expected from controlled animal countermeasure studies?
  attaches_to:
  - pathophysiology#Bone Marrow Hematopoietic Suppression
  rationale: 'Animal efficacy studies support regulatory approval because controlled efficacy experiments involving deliberate harmful human irradiation are unethical or infeasible. Human accident-treatment observations and healthy-volunteer safety/pharmacology studies nevertheless exist. Their designs answer different questions: uncontrolled temporal marrow recovery is not a randomized survival estimate, and healthy-volunteer pharmacology is not irradiated-patient efficacy. Neither the filgrastim macaque experiment nor any single regimen establishes a universal effect for all countermeasures.'
  evidence:
  - reference: PMID:21987000
    reference_title: First global consensus for evidence-based management of the hematopoietic syndrome resulting from exposure to ionizing radiation.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Descriptive studies like these that do not have an appropriate, contemporaneous comparison group allow assessment of hypotheses for possible associations but not robust assessments of causality.
    explanation: Consensus identifies the limitation of uncontrolled accident observations.
    directness: DIRECT
    quote_role: REVIEW_SYNTHESIS
  - reference: url:https://www.accessdata.fda.gov/drugsatfda_docs/label/2021/125268s167lbl.pdf
    reference_title: https://www.accessdata.fda.gov/drugsatfda_docs/label/2021/125268s167lbl.pdf
    supports: SUPPORT
    evidence_source: OTHER
    snippet: Approval for this indication was based on efficacy studies conducted in animals
    explanation: FDA label identifies the regulatory efficacy source.
    directness: DIRECT
    quote_role: BACKGROUND
  - reference: clinicaltrials:NCT02343133
    reference_title: A Phase 2 Single-Dose, Randomized, Double-Blind, Placebo-Controlled Study to Evaluate the Safety, Tolerability, Pharmacokinetics, and Pharmacodynamics of HemaMax™ (rHuIL-12) in Healthy Subjects
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: The purpose of this study is to determine whether HemaMax is safe and well tolerated to support efficacy under FDA's Animal Rule to reduce the morbidity and mortality associated with the hematopoietic syndrome of acute radiation syndrome.
    explanation: Registry description establishes the study purpose and population; it is not an efficacy result.
    directness: DIRECT
classifications:
  harrisons_chapter:
  - classification_value: ENVIRONMENTAL_EXPOSURES
notes: This entry emphasizes acute illness, established countermeasures, supportive care and directly relevant experimental systems. Cutaneous injury can accompany ARS but can also occur after local exposure without systemic ARS. Absorbed-dose boundaries are approximate and source-dependent; CDC ranges quoted here are gamma-equivalent values and are not individual prognostic cutoffs. Delayed radiation effects and exploratory regeneration, microbiome and cell-death pathways are outside the detailed acute pathograph. Clinical-trial records describe research designs and do not establish efficacy in irradiated patients.
has_subtypes:
- name: Hematopoietic subsyndrome
  description: Marrow injury predominates at lower ARS dose ranges. CDC describes the full syndrome usually between 0.7 and 10 Gy; these are approximate gamma-equivalent ranges and do not exclude concomitant organ injury.
  evidence:
  - reference: url:https://www.cdc.gov/radiation-emergencies/hcp/clinical-guidance/ars.html
    reference_title: 'Acute Radiation Syndrome: Information for Clinicians | Radiation Emergencies | CDC'
    supports: SUPPORT
    evidence_source: OTHER
    snippet: the full syndrome will usually occur with a dose between 0.7 and 10 Gy
    explanation: CDC range for the hematopoietic syndrome.
    directness: DIRECT
    quote_role: BACKGROUND
- name: Gastrointestinal subsyndrome
  description: Severe gastrointestinal injury coexists with marrow injury at higher exposures. CDC describes full syndrome usually above approximately 10 Gy, with some symptoms from 6 Gy; other consensus sources use lower syndrome thresholds.
  evidence:
  - reference: url:https://www.cdc.gov/radiation-emergencies/hcp/clinical-guidance/ars.html
    reference_title: 'Acute Radiation Syndrome: Information for Clinicians | Radiation Emergencies | CDC'
    supports: SUPPORT
    evidence_source: OTHER
    snippet: the full syndrome will usually occur with a dose greater than approximately 10 Gy
    explanation: CDC range for full gastrointestinal syndrome.
    directness: DIRECT
    quote_role: BACKGROUND
  - reference: url:https://www.cdc.gov/radiation-emergencies/hcp/clinical-guidance/ars.html
    reference_title: 'Acute Radiation Syndrome: Information for Clinicians | Radiation Emergencies | CDC'
    supports: SUPPORT
    evidence_source: OTHER
    snippet: Some symptoms may occur as low as 6 Gy or 600 rads.
    explanation: Lower-dose symptoms do not imply that all cases have a full gastrointestinal syndrome.
    directness: DIRECT
    quote_role: BACKGROUND
- name: Neurovascular subsyndrome
  description: Very-high-dose cardiovascular and central nervous system injury can evolve within hours. CDC describes full syndrome usually above approximately 50 Gy and some symptoms from 20 Gy; these ranges are source-dependent and are not individual survival cutoffs.
  evidence:
  - reference: url:https://www.cdc.gov/radiation-emergencies/hcp/clinical-guidance/ars.html
    reference_title: 'Acute Radiation Syndrome: Information for Clinicians | Radiation Emergencies | CDC'
    supports: SUPPORT
    evidence_source: OTHER
    snippet: the full syndrome will usually occur with a dose greater than approximately 50 Gy
    explanation: CDC range for full cardiovascular/CNS syndrome.
    directness: DIRECT
    quote_role: BACKGROUND
  - reference: url:https://www.cdc.gov/radiation-emergencies/hcp/clinical-guidance/ars.html
    reference_title: 'Acute Radiation Syndrome: Information for Clinicians | Radiation Emergencies | CDC'
    supports: SUPPORT
    evidence_source: OTHER
    snippet: Some symptoms may occur as low as 20 Gy or 2000 rads.
    explanation: CDC distinguishes lower-dose symptoms from the full syndrome.
    directness: DIRECT
    quote_role: BACKGROUND
- name: Associated cutaneous radiation injury
  description: Skin injury can accompany systemic ARS or follow localized exposure independently. It is an overlapping organ component, not a mandatory systemic stage.
  evidence:
  - reference: url:https://www.cdc.gov/radiation-emergencies/hcp/clinical-guidance/ars.html
    reference_title: 'Acute Radiation Syndrome: Information for Clinicians | Radiation Emergencies | CDC'
    supports: SUPPORT
    evidence_source: OTHER
    snippet: It is also possible to receive a damaging dose to the skin without symptoms of ARS
    explanation: CDC explicitly distinguishes isolated skin irradiation from systemic ARS.
    directness: DIRECT
    quote_role: BACKGROUND
stages:
- name: Prodromal stage
  description: Nausea, vomiting, anorexia and sometimes diarrhea can begin within minutes to days; timing and severity depend on exposure.
  evidence:
  - reference: url:https://www.cdc.gov/radiation-emergencies/hcp/clinical-guidance/ars.html
    reference_title: 'Acute Radiation Syndrome: Information for Clinicians | Radiation Emergencies | CDC'
    supports: SUPPORT
    evidence_source: OTHER
    snippet: The classic symptoms for this stage are nausea, vomiting, as well as anorexia and possibly diarrhea (depending on dose)
    explanation: CDC describes the prodromal symptom cluster.
    directness: DIRECT
    quote_role: BACKGROUND
- name: Latent stage
  description: Symptoms may improve while tissue injury continues. Its duration varies greatly and can be very brief after severe exposure.
  evidence:
  - reference: url:https://www.cdc.gov/radiation-emergencies/hcp/clinical-guidance/ars.html
    reference_title: 'Acute Radiation Syndrome: Information for Clinicians | Radiation Emergencies | CDC'
    supports: SUPPORT
    evidence_source: OTHER
    snippet: In this stage, the patient looks and feels generally healthy for a few hours or even up to a few weeks.
    explanation: The latent interval does not demonstrate recovery.
    directness: DIRECT
    quote_role: BACKGROUND
- name: Manifest illness stage
  description: Organ-specific hematologic, gastrointestinal, skin or neurovascular manifestations emerge; subsyndromes can coexist.
  evidence:
  - reference: url:https://www.cdc.gov/radiation-emergencies/hcp/clinical-guidance/ars.html
    reference_title: 'Acute Radiation Syndrome: Information for Clinicians | Radiation Emergencies | CDC'
    supports: SUPPORT
    evidence_source: OTHER
    snippet: In this stage the symptoms depend on the specific syndrome
    explanation: CDC describes the organ-dependent manifest phase.
    directness: DIRECT
    quote_role: BACKGROUND
- name: Recovery or death
  description: Outcome depends on exposure, residual tissue reserve, associated injury and care. Recovery can take weeks to years; neurovascular death can occur within days.
  evidence:
  - reference: url:https://www.cdc.gov/radiation-emergencies/hcp/clinical-guidance/ars.html
    reference_title: 'Acute Radiation Syndrome: Information for Clinicians | Radiation Emergencies | CDC'
    supports: SUPPORT
    evidence_source: OTHER
    snippet: The recovery process lasts from several weeks up to two years.
    explanation: Recovery time is variable rather than a fixed sequence of subsyndromes.
    directness: DIRECT
    quote_role: BACKGROUND
clinical_trials:
- name: NCT02343133
  description: Safety Study of HemaMax™ (rHuIL-12) to Treat Acute Radiation Syndrome. Safety/pharmacology research in healthy volunteers; it does not test survival benefit in ARS casualties.
  phase: PHASE_II
  status: COMPLETED
  evidence:
  - reference: clinicaltrials:NCT02343133
    reference_title: A Phase 2 Single-Dose, Randomized, Double-Blind, Placebo-Controlled Study to Evaluate the Safety, Tolerability, Pharmacokinetics, and Pharmacodynamics of HemaMax™ (rHuIL-12) in Healthy Subjects
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: The purpose of this study is to determine whether HemaMax is safe and well tolerated to support efficacy under FDA's Animal Rule to reduce the morbidity and mortality associated with the hematopoietic syndrome of acute radiation syndrome.
    explanation: Registry description establishes the study purpose and population; it is not an efficacy result.
    directness: DIRECT
  notes: Registry status checked on 2026-09-21. Unknown status is not evidence of current recruitment.
- name: NCT01742221
  description: Safety and Tolerability of HemaMax™ (rHuIL-12) as Radiation Countermeasure. Safety/pharmacology research in healthy volunteers; it does not test survival benefit in ARS casualties.
  phase: PHASE_I
  status: COMPLETED
  evidence:
  - reference: clinicaltrials:NCT01742221
    reference_title: A Phase 1b, Single-Dose, Randomized, Double-Blind, Placebo-Controlled Study to Evaluate the Safety, Tolerability, Pharmacokinetics, and Pharmacodynamics of HemaMax™ (rHuIL-12) in Healthy Subjects
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: This trial is designed to evaluate the safety, pharmacokinetics, and pharmacodynamics of HemaMax in healthy male and female volunteers.
    explanation: Registry description establishes the study purpose and population; it is not an efficacy result.
    directness: DIRECT
  notes: Registry status checked on 2026-09-21. Unknown status is not evidence of current recruitment.
- name: NCT03585803
  description: A Clinical Trial to Evaluate Safety, Tolerability and Pharmacokinetic/Pharmacodynamic Characteristics of KMRC 011. Safety/pharmacology research in healthy volunteers; it does not test survival benefit in ARS casualties.
  phase: PHASE_I
  status: COMPLETED
  evidence:
  - reference: clinicaltrials:NCT03585803
    reference_title: A Dose Blocked-Randomized, Single-Blind, Placebo-Controlled and Dose-Escalation Phase I Clinical Trial to Evaluate Safety, Tolerability and Pharmacokinetic/Pharmacodynamic Characteristics of KMRC011 After Intramuscular Administration in Healthy Adult Volunteers
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: This trial is designed to evaluate the safety, tolerability, pharmacokinetic and pharmacodynamic of KMRC011 injection in healthy adult volunteers.
    explanation: Registry description establishes the study purpose and population; it is not an efficacy result.
    directness: DIRECT
  notes: Registry status checked on 2026-09-21. Unknown status is not evidence of current recruitment.
- name: NCT06741345
  description: Phase 1 BIO 300 Oral Suspension. Safety/pharmacology research in healthy volunteers; it does not test survival benefit in ARS casualties.
  phase: PHASE_I
  status: COMPLETED
  evidence:
  - reference: clinicaltrials:NCT06741345
    reference_title: A Phase 1 Multiple Ascending Dose and Food Effect Trial of BIO 300 Oral Suspension in Healthy Volunteers
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: This is a two-part study of BIO 300 Oral Suspension in healthy male and female volunteers.
    explanation: Registry description establishes the study purpose and population; it is not an efficacy result.
    directness: DIRECT
  notes: Registry status checked on 2026-09-21. Unknown status is not evidence of current recruitment.
- name: NCT03797040
  description: Open-label Phase I Study for PEP or Treatment of HS-ARS PLX-R 18 for the Post-Exposure Prevention (PEP) or Treatment of Hematopoietic Syndrome of Acute Radiation Syndrome (HS-ARS). A safety protocol for people exposed to ionizing radiation; registration alone does not document enrollment or benefit.
  phase: PHASE_I
  status: UNKNOWN
  evidence:
  - reference: clinicaltrials:NCT03797040
    reference_title: Open-label Phase I Study to Evaluate the Safety of PLX-R18 for the Post-Exposure Prevention (PEP) or Treatment of Hematopoietic Syndrome of Acute Radiation Syndrome (HS-ARS)
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: The objective of the study is to evaluate the safety of intramuscular (IM) administration of PLX-R18 in subjects exposed to ionizing radiation and who are at risk of developing HS-ARS.
    explanation: Registry description establishes the study purpose and population; it is not an efficacy result.
    directness: DIRECT
  notes: Registry status checked on 2026-09-21. Unknown status is not evidence of current recruitment.
- name: NCT04650555
  description: BIO 300 Oral Powder Safety and Pharmacokinetics. Safety/pharmacology research in healthy volunteers; it does not test survival benefit in ARS casualties.
  phase: PHASE_I
  status: COMPLETED
  evidence:
  - reference: clinicaltrials:NCT04650555
    reference_title: A Phase 1 Dose Escalation Trial Evaluating the Safety and Pharmacokinetic Profile of BIO 300 Oral Powder in Healthy Volunteers
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Open-label, single ascending dose and multiple single dose study in healthy volunteers to evaluate the safety and pharmacokinetics of BIO 300 Oral Powder (BIO 300). The single ascending dose study consists of 4 ascending dose cohorts and the multiple single dose study consists of a single dose given daily for 6 consecutive days.
    explanation: Registry description establishes the study purpose and population; it is not an efficacy result.
    directness: DIRECT
  notes: Registry status checked on 2026-09-21. Unknown status is not evidence of current recruitment.
- name: NCT00504335
  description: Safety and Pharmacokinetic Study of BIO 300 Capsules. Safety/pharmacology research in healthy volunteers; it does not test survival benefit in ARS casualties.
  phase: PHASE_I
  status: COMPLETED
  evidence:
  - reference: clinicaltrials:NCT00504335
    reference_title: A Dose Escalation Trial Evaluating the Safety and Pharmacokinetic Profiles of BIO 300 Capsules in Healthy Male and Female Volunteers
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: This trial is designed to evaluate the safety and pharmacokinetics of BIO 300 capsules when administered orally to healthy male and female volunteers.
    explanation: Registry description establishes the study purpose and population; it is not an efficacy result.
    directness: DIRECT
  notes: Registry status checked on 2026-09-21. Unknown status is not evidence of current recruitment.
- name: NCT02587442
  description: A Study to Evaluate the Safety and Pharmacokinetics of RadProtect® in Healthy Volunteers. Safety/pharmacology research in healthy volunteers; it does not test survival benefit in ARS casualties.
  phase: PHASE_I
  status: UNKNOWN
  evidence:
  - reference: clinicaltrials:NCT02587442
    reference_title: A Phase I Study to Evaluate the Safety and Pharmacokinetics of RadProtect® in Healthy Volunteers
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: This is a Phase 1, non-randomized, sequential-cohort, dose escalation, open-label study designed to evaluate the safety and tolerability of RadProtect® in healthy volunteers. This study is to be conducted at two clinical centers and in conformity with Good Clinical Practice (GCP).
    explanation: Registry description establishes the study purpose and population; it is not an efficacy result.
    directness: DIRECT
  notes: Registry status checked on 2026-09-21. Unknown status is not evidence of current recruitment.
experimental_models:
- name: Irradiated resting human lymphocytes
  experimental_model_type: PRIMARY_CELL_CULTURE
  organism:
    preferred_term: Homo sapiens
    term:
      id: NCBITaxon:9606
      label: Homo sapiens
  cell_source: Primary peripheral-blood lymphocytes from healthy donors.
  publication: PMID:9525257
  description: Resting lymphocytes were irradiated with cobalt-60 gamma rays or fast neutrons and evaluated for apoptosis after 24 hours of culture. Doses ranged from 0.05 to 5 Gy.
  modeled_mechanisms:
  - target: Mature Lymphocyte Apoptosis
    relationship: RECAPITULATES
    fidelity: MODERATE
    description: Demonstrates early interphase apoptosis in nondividing lymphocytes.
    limitations: Ex-vivo assay, not whole-body exposure or an ARS patient cohort; it does not alone establish clinical depletion kinetics.
    evidence:
    - reference: PMID:9525257
      reference_title: Apoptosis induced by fast neutrons versus 60Co gamma-rays in human peripheral blood lymphocytes.
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: The dose-response data confirm the high radiosensitivity of lymphocytes and demonstrate that their response to undergo early interphase cell death by apoptosis is largely independent of LET.
      explanation: Resting human lymphocytes underwent apoptosis after ex-vivo irradiation; cell division is not required.
      directness: DIRECT
      quote_role: PRIMARY_RESULT
    readouts:
    - name: Apoptotic lymphocyte yield
      target: Mature Lymphocyte Apoptosis
      direction: INCREASED
      interpretation: Apoptotic yield increased steeply below 1 Gy and flattened toward 5 Gy.
      evidence:
      - reference: PMID:9525257
        reference_title: Apoptosis induced by fast neutrons versus 60Co gamma-rays in human peripheral blood lymphocytes.
        supports: SUPPORT
        evidence_source: IN_VITRO
        snippet: Dose-response curves obtained with both radiation qualities were characterized by an initial steep increase in the number of apoptotic cells below 1 Gy, with a flattening of the curves at higher doses towards 5 Gy.
        explanation: Measured ex-vivo dose response.
        directness: DIRECT
        quote_role: PRIMARY_RESULT
- name: Healthy-donor blood dicentric biodosimetry assay
  experimental_model_type: PRIMARY_CELL_CULTURE
  organism:
    preferred_term: Homo sapiens
    term:
      id: NCBITaxon:9606
      label: Homo sapiens
  cell_source: Healthy-donor peripheral blood, with cultured mononuclear cells.
  publication: PMID:36543843
  description: DLADES dose-response calibration used blood from two donors irradiated with cobalt-60 gamma rays at 0–4 Gy and 0.8 Gy/min. Two other donors provided blinded samples. Chromosome-number filtering improved image selection.
  modeled_mechanisms:
  - target: Radiation-Induced Chromosomal Aberrations
    relationship: MEASURES
    fidelity: MODERATE
    description: Measures acquired dicentrics for calibrated dose estimation.
    limitations: Healthy blood irradiated ex vivo, not ARS casualties; only four donors overall. The blinded evaluation spanned 0.5–4 Gy. The 0.5 Gy sample had no finite lower confidence bound; lower/higher doses, heterogeneous exposures and other radiation qualities were not validated.
    evidence:
    - reference: PMID:36543843
      reference_title: Dicentric chromosome assay using a deep learning-based automated system.
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: Blood samples from two donors were exposed to cobalt-60 gamma rays (0-4 Gy, 0.8 Gy/min).
      explanation: Abstract specifies the calibration exposure.
      directness: DIRECT
      quote_role: PRIMARY_RESULT
    readouts:
    - name: Blind-sample dose reconstruction
      target: Radiation-Induced Chromosomal Aberrations
      interpretation: The known doses lay within the reported 95% confidence limits after quality filtering, with an undefined lower bound for the 0.5 Gy sample.
      evidence:
      - reference: PMID:36543843
        reference_title: Dicentric chromosome assay using a deep learning-based automated system.
        supports: SUPPORT
        evidence_source: IN_VITRO
        snippet: The actual dose for each sample was within the 95% confidence limits of the estimated dose.
        explanation: Performance finding applies only to the tested ex-vivo samples.
        directness: DIRECT
        quote_role: PRIMARY_RESULT
references:
- reference: PMID:17993851
  title: Estimating radiation dose from time to emesis and lymphocyte depletion.
- reference: PMID:21986999
  title: Literature review and global consensus on management of acute radiation syndrome affecting nonhematopoietic organ systems.
- reference: PMID:21987000
  title: First global consensus for evidence-based management of the hematopoietic syndrome resulting from exposure to ionizing radiation.
- reference: PMID:23210705
  title: Filgrastim improves survival in lethally irradiated nonhuman primates.
- reference: PMID:34402734
  title: 'Radiation countermeasures for hematopoietic acute radiation syndrome: growth factors, cytokines and beyond.'
- reference: PMID:36543843
  title: Dicentric chromosome assay using a deep learning-based automated system.
- reference: PMID:9525257
  title: Apoptosis induced by fast neutrons versus 60Co gamma-rays in human peripheral blood lymphocytes.
- reference: clinicaltrials:NCT00504335
  title: A Dose Escalation Trial Evaluating the Safety and Pharmacokinetic Profiles of BIO 300 Capsules in Healthy Male and Female Volunteers
- reference: clinicaltrials:NCT01742221
  title: A Phase 1b, Single-Dose, Randomized, Double-Blind, Placebo-Controlled Study to Evaluate the Safety, Tolerability, Pharmacokinetics, and Pharmacodynamics of HemaMax™ (rHuIL-12) in Healthy Subjects
- reference: clinicaltrials:NCT02343133
  title: A Phase 2 Single-Dose, Randomized, Double-Blind, Placebo-Controlled Study to Evaluate the Safety, Tolerability, Pharmacokinetics, and Pharmacodynamics of HemaMax™ (rHuIL-12) in Healthy Subjects
- reference: clinicaltrials:NCT02587442
  title: A Phase I Study to Evaluate the Safety and Pharmacokinetics of RadProtect® in Healthy Volunteers
- reference: clinicaltrials:NCT03585803
  title: A Dose Blocked-Randomized, Single-Blind, Placebo-Controlled and Dose-Escalation Phase I Clinical Trial to Evaluate Safety, Tolerability and Pharmacokinetic/Pharmacodynamic Characteristics of KMRC011 After Intramuscular Administration in Healthy Adult Volunteers
- reference: clinicaltrials:NCT03797040
  title: Open-label Phase I Study to Evaluate the Safety of PLX-R18 for the Post-Exposure Prevention (PEP) or Treatment of Hematopoietic Syndrome of Acute Radiation Syndrome (HS-ARS)
- reference: clinicaltrials:NCT04650555
  title: A Phase 1 Dose Escalation Trial Evaluating the Safety and Pharmacokinetic Profile of BIO 300 Oral Powder in Healthy Volunteers
- reference: clinicaltrials:NCT06741345
  title: A Phase 1 Multiple Ascending Dose and Food Effect Trial of BIO 300 Oral Suspension in Healthy Volunteers
- reference: url:https://www.accessdata.fda.gov/drugsatfda_docs/label/2015/125031s180lbl.pdf
  title: https://www.accessdata.fda.gov/drugsatfda_docs/label/2015/125031s180lbl.pdf
- reference: url:https://www.accessdata.fda.gov/drugsatfda_docs/label/2021/125268s167lbl.pdf
  title: https://www.accessdata.fda.gov/drugsatfda_docs/label/2021/125268s167lbl.pdf
- reference: url:https://www.cdc.gov/radiation-emergencies/hcp/clinical-guidance/ars.html
  title: 'Acute Radiation Syndrome: Information for Clinicians | Radiation Emergencies | CDC'
- reference: url:https://www.fda.gov/emergency-preparedness-and-response/medical-countermeasure-mcm-issues/radiological-and-nuclear-emergency-preparedness
  title: Radiological and Nuclear Emergency Preparedness | FDA

📚

References & Deep Research

References

PMID:17993851

Estimating radiation dose from time to emesis and lymphocyte depletion.

No top-level findings curated for this source.

PMID:21986999

Literature review and global consensus on management of acute radiation syndrome affecting nonhematopoietic organ systems.

No top-level findings curated for this source.

PMID:21987000

First global consensus for evidence-based management of the hematopoietic syndrome resulting from exposure to ionizing radiation.

No top-level findings curated for this source.

PMID:23210705

Filgrastim improves survival in lethally irradiated nonhuman primates.

No top-level findings curated for this source.

PMID:34402734

Radiation countermeasures for hematopoietic acute radiation syndrome: growth factors, cytokines and beyond.

No top-level findings curated for this source.

PMID:36543843

Dicentric chromosome assay using a deep learning-based automated system.

No top-level findings curated for this source.

PMID:9525257

Apoptosis induced by fast neutrons versus 60Co gamma-rays in human peripheral blood lymphocytes.

No top-level findings curated for this source.

clinicaltrials:NCT00504335

A Dose Escalation Trial Evaluating the Safety and Pharmacokinetic Profiles of BIO 300 Capsules in Healthy Male and Female Volunteers

No top-level findings curated for this source.

clinicaltrials:NCT01742221

A Phase 1b, Single-Dose, Randomized, Double-Blind, Placebo-Controlled Study to Evaluate the Safety, Tolerability, Pharmacokinetics, and Pharmacodynamics of HemaMax™ (rHuIL-12) in Healthy Subjects

No top-level findings curated for this source.

clinicaltrials:NCT02343133

A Phase 2 Single-Dose, Randomized, Double-Blind, Placebo-Controlled Study to Evaluate the Safety, Tolerability, Pharmacokinetics, and Pharmacodynamics of HemaMax™ (rHuIL-12) in Healthy Subjects

No top-level findings curated for this source.

clinicaltrials:NCT02587442

A Phase I Study to Evaluate the Safety and Pharmacokinetics of RadProtect® in Healthy Volunteers

No top-level findings curated for this source.

clinicaltrials:NCT03585803

A Dose Blocked-Randomized, Single-Blind, Placebo-Controlled and Dose-Escalation Phase I Clinical Trial to Evaluate Safety, Tolerability and Pharmacokinetic/Pharmacodynamic Characteristics of KMRC011 After Intramuscular Administration in Healthy Adult Volunteers

No top-level findings curated for this source.

clinicaltrials:NCT03797040

Open-label Phase I Study to Evaluate the Safety of PLX-R18 for the Post-Exposure Prevention (PEP) or Treatment of Hematopoietic Syndrome of Acute Radiation Syndrome (HS-ARS)

No top-level findings curated for this source.

clinicaltrials:NCT04650555

A Phase 1 Dose Escalation Trial Evaluating the Safety and Pharmacokinetic Profile of BIO 300 Oral Powder in Healthy Volunteers

No top-level findings curated for this source.

clinicaltrials:NCT06741345

A Phase 1 Multiple Ascending Dose and Food Effect Trial of BIO 300 Oral Suspension in Healthy Volunteers

No top-level findings curated for this source.

url:https://www.accessdata.fda.gov/drugsatfda_docs/label/2015/125031s180lbl.pdf

https://www.accessdata.fda.gov/drugsatfda_docs/label/2015/125031s180lbl.pdf

No top-level findings curated for this source.

url:https://www.accessdata.fda.gov/drugsatfda_docs/label/2021/125268s167lbl.pdf

https://www.accessdata.fda.gov/drugsatfda_docs/label/2021/125268s167lbl.pdf

No top-level findings curated for this source.

url:https://www.cdc.gov/radiation-emergencies/hcp/clinical-guidance/ars.html

Acute Radiation Syndrome: Information for Clinicians | Radiation Emergencies | CDC

No top-level findings curated for this source.

url:https://www.fda.gov/emergency-preparedness-and-response/medical-countermeasure-mcm-issues/radiological-and-nuclear-emergency-preparedness

Radiological and Nuclear Emergency Preparedness | FDA

No top-level findings curated for this source.

Deep Research

Deep research results are used as seeds for research; they do not undergo the same validation as the main records and may contain errors. How we use deep research.

Evaluations and curation notes (2)

Review acute radiation syndrome using full consensus texts, animal studies and regulatory guidance · 2026-09-21T06:26:57Z · View source

# Acute radiation syndrome source review Reviewed the original entry against every cited cached source, the matching deep-research report, current CDC/FDA guidance and directly retrieved registry protocols. Base eaa5fe99; parsed CREATE-only history. GeneReviews and StatPearls dated index (2026-09-10) both report NO_CHAPTER. Fresh fully paginated PR-file overlap preflight is saved separately. ## Original references - PMID34402734: complete 2021 review abstract. Sanctioned full-text refresh did not improve the available cache. Its claim that romiplostim is a small molecule was corrected using the FDA label (Fc-peptide fusion peptibody). The reference remains useful for growth-factor mechanisms, with its scope explicit. - PMID17993851: complete abstract; sanctioned refresh did not recover full text. Regression based on more than 100 radiation-accident cases supports time to emesis and lymphocyte kinetics as components of assessment, not exact individual dosimetry. - PMID23210705: complete cached scientific body, methods/results/discussion and tables/legends read. Forty-six Chinese-substrain rhesus macaques (38 males, 8 females), 7.5 Gy LINAC irradiation at 0.8 Gy/min; 24 treated versus 22 controls, both receiving medical management. Filgrastim began 23±3 hours after irradiation. Mortality was 20.8% versus 59.1%, a 38.3-percentage-point difference under this protocol. Neutropenia duration shortened, but ANC nadir, febrile-neutropenia incidence, diarrhea and selected platelet outcomes did not significantly improve. Animal results are not human effect estimates or evidence for all four parent drugs. - PMID36543843: complete ten-page scientific PDF text including methods, results, discussion, tables and legends. Ex-vivo healthy blood, two calibration donors and two independent validation donors; cobalt-60 irradiation, 0–4 Gy calibration, five blinded doses 0.5–4 Gy. Actual doses were within confidence intervals, with one lower confidence bound unavailable at 0.5 Gy. One calibration point remained overdispersed after filtering. This does not validate an assay in ARS casualties, partial-body exposure, doses above 4 Gy or below 0.5 Gy. Background diagnostic statements and experimental results are classified separately. ## Expanded full-text evidence - PMID21987000: complete 2011 WHO hematopoietic consensus main scientific body and tables. Human accident experience includes 18 cytokine-treated cases without adequate untreated comparators; spontaneous recovery can occur. Distinguishes suppression of progenitor mitosis from mature lymphocyte apoptosis. Strong G-CSF/GM-CSF recommendations, weak ESA and transplantation recommendations. ESA response takes weeks; selection and labeling warnings matter. Transplantation is conditional on lack of spontaneous/cytokine recovery after 2–3 weeks and absence of significant other-organ injury. Its historical lack of a thrombopoietic recommendation is superseded by current FDA romiplostim approval. - PMID21986999: complete 2011 nonhematopoietic consensus scientific text and tables read, first in the generated USZ PDF and then canonical full XML. Clinical GI, skin and neurovascular findings; barrier damage with bacterial translocation qualified as a possible mechanism; enteral support with ileus/diffuse-bleeding exceptions; antimicrobials, antiemetics, diarrhea control, topical care, conditional excision/grafting, psychological support and ICU organ support. Source-specific dose thresholds are not universal. Neurovascular edema/permeability mechanisms remain inferred. The inpatient scenario and extrapolated critical-care evidence are distinguished from direct ARS trials. Obsolete generic ICU recommendations were not imported (e.g. activated protein C). - PMID9525257: complete abstract; full-text retrieval did not succeed. Resting human lymphocytes exposed ex vivo to cobalt-60 or fast neutrons, 0.05–5 Gy, analyzed at 24 hours. Apoptosis rises steeply at low dose and flattens at high dose; this supports a separate mature-lymphocyte mechanism, not clinical timing estimates. - PMID35767939: complete 2022 review abstract read; full-text attempt timed out. Reiterates the limitations of controlled human evidence. Not needed as a redundant citation. - PMID24376971: complete abstract; publisher/PMC retrieval did not yield accessible full text. Its mixed countermeasure discussion requires irradiation-versus-internal-contamination distinctions. Better full consensus sources were used instead. ## Regulatory and clinical guidance - CDC clinical ARS page: complete generated HTML body and table footnotes. Distinguishes dose thresholds from temporal onset and distinguishes localized cutaneous injury from systemic ARS. Four clinical stages, serial assessment, broad symptom support and approximate gamma-equivalent dose ranges were consumed. Not population frequency data. - FDA radiological/nuclear preparedness page: complete generated HTML body, content current 2026-07-13. Confirms four parent agents and subsequent biosimilar approvals. Internal contamination and potassium iodide content was not conflated with treatment of external-radiation ARS. - FDA romiplostim 2021 label: relevant indication, molecular structure, mechanism, pharmacology and ARS efficacy sections read in full; unrelated ITP and patient instructions were not read in full. Forty animals per randomized blinded rhesus arm, 6.8 Gy cobalt-60, treatment at 24 hours with medical management; survival 29/40 versus 13/40. The exploratory combination arm is not a clinical comparison. No animal dose was curated because the extracted PDF unit is ambiguous. Human ARS pharmacokinetics were unavailable; dose bridging uses other human settings and animal efficacy. - FDA pegfilgrastim 2015 label: relevant indication, mechanism, ARS pharmacology/human bridge, safety context and efficacy section read in full; unrelated cancer/device instructions were not read in full. Separate macaque study, 23 per arm, 7.5±0.15 Gy, dosing on days 1 and 8 with medical management; survival 21/23 versus 11/23. No transfer of animal regimens into patient dosing instructions. - Generated URL-PDF metadata use URL titles. Human-readable identities are provided in evidence explanations, descriptions and this audit; cache metadata were not hand-edited. ## Registry and research completeness All eight included registry cache summaries were read in full, with directly retrieved protocol identification/status/design/intervention/population/endpoints inspected on 2026-09-21. HemaMax NCT01742221 is Phase I and NCT02343133 Phase II, both healthy-volunteer safety/pharmacology research. KMRC011 NCT03585803 and three BIO300 studies NCT06741345/NCT04650555/NCT00504335 are also healthy-volunteer development, not ARS survival trials. NCT03797040 (PLX-R18) is an exposed-person safety protocol with UNKNOWN status; estimated enrollment is not an observed result. NCT02587442 (RadProtect) is a healthy-volunteer protocol with UNKNOWN status. NCT00903929 concerns planned transplant-conditioning irradiation and was excluded from uncontrolled acute exposure scope. Read the entire actual deep-research report (scientific text lines 513–1590); preceding material is the retrieval prompt. Its citation analysis resolves 68 references, 44 on-topic, but report leads are not proof. Corrected its overgeneralized HSC cycling, syndrome timing and supposed permanent ceiling on all human research. Central acute mechanisms, four overlapping organ components, stages, clinical manifestations, diagnostic limitations, supportive care, approved agents and the Phase-II healthy-volunteer record are represented. Late radiation effects and exploratory regeneration/microbiome mechanisms are explicitly outside this acute entry's reviewed scope; animal-only findings were not promoted to human phenotypes. ## Final review Thirteen atomic pathophysiology nodes distinguish delayed marrow suppression, rapid mature-lymphocyte injury, GI barrier failure, skin injury, inferred neurovascular injury and cytogenetic damage. Twenty-four evidence-backed acute phenotypes; eighteen treatments; three distinct macaque models; two human ex-vivo models; eight registry records. A second agent independently read both consensus main bodies/tables, CDC/FDA guidance and relevant label efficacy sections and found no clinical/evidence blocker after duplicate-record and treatment-direction fixes. Full schema/ontology/reference validation passes with 172/172 snippets; final additional gates and formatting are tracked separately.

Create Acute Radiation Syndrome conforming to myelosuppression · 2026-09-01T17:50:16Z · View source

New entry for the haematopoietic subsyndrome of acute radiation syndrome, absent from the KB. The myelosuppression module names ionizing radiation among its cytotoxic insults, so the conformance is one the module already anticipated. Three pathophysiology nodes, all three conforming to the module. The framing the entry adds beyond the module is that marrow fails first because its progenitors are the most rapidly cycling, which is the same reason it is dose-limiting for cytotoxic chemotherapy - the insult differs but the vulnerable cell population does not. Filgrastim and romiplostim both join the marrow-suppression node with RESTORES, since they rescue output from surviving progenitors rather than preventing the radiation injury itself. A HUMAN_MODEL_MISMATCH discussion records the epistemically unusual feature of this indication. Every treatment here carries MODEL_ORGANISM evidence, and that ceiling is permanent by regulatory design rather than a gap in curation: countermeasures are approved under the FDA Animal Rule, which permits approval on animal efficacy data precisely because deliberately irradiating humans to test a drug is neither ethical nor feasible. The efficacy claims can therefore never be upgraded to HUMAN_CLINICAL by finding a better trial, because no such trial will exist. The open question is how dose-equivalence and supportive-care differences between a primate protocol and a mass-casualty setting affect expected benefit. A curation error worth recording. The exposure was first bound to ECTO:0000006 (exposure to ultraviolet radiation), which is wrong - ultraviolet is non-ionizing and does not produce this syndrome - and was accompanied by a notes block asserting that no better term was available and that this was the least-bad option. That note was false: ECTO:7000047 (exposure to ionizing radiation) was already in the validated cache and resolves in the local ECTO build. The justification had been written without running the search. It is now bound correctly and the notes record what happened, because a confident but wrong rationale is more damaging than a bare wrong binding - a later curator would have trusted it and left the term alone. Deep research was run with claude_code and is committed as provenance. No quote from it was curated; all evidence was independently sourced and pre-verified against the local cache, and reference_title values were generated from cache rather than typed. Validated with just validate-disorders (batched sweep CI runs), just count-verified-snippets (7/7), just check-duplicate-keys, just check-entity-refs, and a graph build showing 5 edges with no integrity issues.

Claude Code ▸

Acute Radiation Syndrome — Disease Characteristics Research Report

claude-haiku-4-5-20251001, claude-opus-5[1m] 90 citations 2026-09-01T12:33:58.907524

Acute Radiation Syndrome — Disease Characteristics Research Report

Prepared: 2026-09-01 · Target: Acute Radiation Syndrome · MONDO:0033938 · Category: Complex (environmental / toxicologic, non-Mendelian)

⚠️ Read this before you paste anything into a `snippet:` field

Every quoted fragment below came out of PubMed's efetch records through an automated retrieval layer, which means a summarizing model touched them on the way here. They are almost certainly verbatim, but "almost certainly" is exactly the failure mode that eats a whole curation session three PRs later. So:

Run just fetch-reference PMID:<id> and re-verify every snippet against the cache before it goes into YAML. Treat this whole document the way the repo already tells you to treat a deep-research report — as leads, not as evidence.

Same deal with the ontology terms. I've split them into two buckets: - ✅ VERIFIED — I looked the CURIE up either in this repo's own cache/<prefix>/terms.csv (which is authority-backed and already passing term validation elsewhere in the KB) or live against EBI OLS4. The id↔label pair is real. - 🔎 LEAD — a plausible term I did not resolve. Do not bind it until just validate-terms says yes.

sup. Let's get into it.

1. Disease Information

What it is

Acute radiation syndrome is what happens when a body absorbs a big dose of penetrating ionizing radiation all at once. It isn't one disease so much as a scheduling problem: radiation preferentially kills cells that are dividing, and the body's fastest-dividing tissues are the ones constantly rebuilding themselves — bone marrow, gut lining, skin, gonads. The mature cells already made keep working until they hit their normal expiry date. Then nothing replaces them. So the illness arrives on a timetable set by the half-life of each cell type, which is why ARS has that eerie "feels fine for a week, then falls apart" shape. It's less like a poisoning and more like quietly firing the entire maintenance staff of a building and waiting.

Orphanet's definition (ORPHA:454831):

"Acute radiation syndrome is a rare radiation-induced disorder resulting from whole body exposure to large doses of penetrating radiation (>0.7 Gray) within a very short period of time (usually minutes) and characterized by bone marrow syndrome with pancytopenia, gastrointestinal syndrome, and cardiovascular/central nervous system syndrome."

Four conditions have to be met simultaneously for ARS (this is the CDC framing): the dose must be large, the radiation must be penetrating (gamma, X-ray, neutrons — an external alpha or low-energy beta source can't reach marrow), it must hit most or all of the body, and it must be delivered in a short time at high dose rate. Drop any one of those four and you get a different disease. Chronic low-dose exposure, internal contamination, and a localized radiotherapy field are all not ARS, which matters for scoping the KB entry.

Identifiers

Resource	Identifier	Status
MONDO	MONDO:0033938 — "acute radiation syndrome"	✅ VERIFIED (OLS4 + local `cache/mondo/terms.csv`)
Orphanet	ORPHA:454831 — "Acute radiation syndrome"	✅ VERIFIED (orpha.net)
ICD-10-CM	T66 "Radiation sickness, unspecified" (billable children: `T66.XXXA` initial, `T66.XXXD` subsequent, `T66.XXXS` sequela)	✅ VERIFIED
MeSH	D054508 "Acute Radiation Syndrome"	✅ VERIFIED
ICD-11	one source returned `NF00`; the prompt guessed `NF06`. These disagree.	🔎 LEAD — resolve against the ICD-11 browser before binding `icd11f`
OMIM	Not applicable — no Mendelian entry, this is not a heritable disease	—
DOID	not retrieved	🔎 LEAD

MONDO synonym on record: "Acute radiation sickness". Other names in common clinical and lay use: radiation poisoning, radiation toxicity, radiation sickness, and in the older Soviet/Ukrainian literature acute radiation disease (ARD).

Where the knowledge comes from — and why this matters for evidence grading

This is the unusual bit and it should shape the whole entry. Human ARS knowledge is aggregated from a small number of catastrophes, not from cohorts or EHR. The total documented human experience is a few thousand people across ~80 years. Lazarus & Gale put it bluntly (PMID:40074513, Best Pract Res Clin Haematol 2024):

"Radiological accidents/incidents are common with nearly 400 reported since 1944 exposing about 3000 people to substantial doses of ionizing radiations with 127 deaths."

So the sources stack like this: - Accident registries and case series — REAC/TS Radiation Accident Registry (Oak Ridge), IAEA accident reports, the Ukrainian Chernobyl ARS survivor cohort. - Atomic bomb survivor data (RERF, Hiroshima/Nagasaki) — the largest human dose-response dataset, but confounded by blast, burns, and wartime lack of medical care. - Iatrogenic near-analogs — total body irradiation conditioning before transplant is essentially a controlled ARS, and is the reason we know anything at all about supportive care windows. - Animal-Rule preclinical studies — because you cannot ethically run an ARS efficacy trial, the FDA's Animal Rule means every approved drug for this disease was licensed on non-human primate and rodent data. Christy & Herzig say it plainly (PMID:39000080): "Since clinical trials for ARS cannot be ethically conducted, animal testing is extremely important."

Curation consequence: a large fraction of the mechanistic evidence for this entry will legitimately carry evidence_source: MODEL_ORGANISM, and that's not a defect — it's the epistemic structure of the field. But per the repo's own rule, model-organism evidence should not be the only support for a human phenotype, and here the human phenotypes genuinely are documented (Chernobyl, Goiânia, Tokai-mura). Keep the two layers distinct.

2. Etiology

Primary cause

One cause, no ambiguity: acute, high-dose-rate, whole-body or significant partial-body exposure to penetrating ionizing radiation.

Exposure term: ECTO:7000047 — "exposure to ionizing radiation" ✅ VERIFIED (local cache/ecto/terms.csv; already bound elsewhere in the KB, so it validates offline).

This is the entry's single initiating node, and it should be wired into the pathograph via environmental[].influences_mechanisms with environmental_effect: TRIGGERS, not left as a floating list item. There is no other etiology to model.

Exposure scenarios (the real-world routes)

Scenario	Worked example	Notes
Reactor accident	Chernobyl 1986; Fukushima Daiichi 2011	Chernobyl produced the largest ARS case series ever assembled
Criticality accident	Tokaimura, Japan, 30 Sept 1999	Uranium conversion plant; 2 worker deaths; mixed neutron/gamma field
Orphan / lost source	Goiânia, Brazil, 13 Sept 1987	Cs-137 teletherapy source cracked open and handled by the public; 4 ARS deaths, ~250 contaminated
Nuclear detonation	Hiroshima, Nagasaki 1945	Combined injury — blast + thermal burn + radiation
Industrial radiography	numerous	Usually localized/cutaneous rather than whole-body
Radiological dispersal device ("dirty bomb") / deliberate act	threat scenario	Drives most current countermeasure funding
Medical/radiotherapy accident	numerous	Usually partial-body
Iatrogenic TBI conditioning	routine	Intentional, controlled, marrow-rescued ARS

Feldman & Kazzi (PMID:37280005) note the driver behind the recent surge in preparedness work:

"The conflict in Ukraine has raised the specter of radiological and nuclear incidents, including fighting at the Zaporizhzhia nuclear plant, the largest nuclear powerplant in Europe; concerns that a radiological dispersion device ('dirty bomb') may be used; and threats to deploy tactical nuclear weapons. Children are more susceptible than adults to immediate and delayed radiation health effects."

Dose–effect thresholds (the load-bearing numbers)

These are the numbers that structure the whole entry, so get them right and cite them individually rather than as a block.

Threshold	Value	Source
ARS possible at all	>0.7 Gy whole body (some references say ~1 Gy for clinically overt ARS at high dose rate)	Orphanet ORPHA:454831; CDC
H-ARS (hematopoietic) onset	≥ ~2 Gy clinically overt; damage begins ~0.7 Gy	Christy & Herzig PMID:39000080 — "Exposure to a whole-body radiation dose above about 0.7 Gy results in H-ARS"
GI-ARS onset	~6 Gy	Freeman PMID:40368913 — "GI-ARS occurs at radiation doses of 6 Gy, with doses of ≥10 Gy typically resulting in death within 10 days."
Uniformly lethal GI dose	≥10 Gy → death within ~10 days	same
Limit of current therapy	>12 Gy	Arnautou & Garnier PMID:39025400 — "Radiation doses below 2 Gray generally result in insignificant clinical consequences, while exposures surpassing 12 Gray exceeds current therapeutic capacities."
Neurovascular / CNS syndrome	>20–50 Gy (sources vary; commonly cited >50 Gy for the fulminant form)	see §6 Branch D
Human LD50/60, no medical care	~2.7–3.1 Gy marrow dose (DS02 dosimetry, A-bomb data); 2.3–2.6 Gy by the earlier DS86 system	Fujita, Kato & Schull PMID:1762100, PMID:2693695
Human LD50/60, with modern supportive care	commonly quoted ~4.5 Gy, plausibly higher with cytokines	secondary literature — ⚠️ this number is soft; do not present it as a measured value

A caution worth writing into notes:. The A-bomb LD50 is lower than the textbook "3.5–4.5 Gy" figure, and the difference isn't a contradiction — it's confounding. Hiroshima and Nagasaki survivors had concurrent burns, blast trauma, malnutrition, and essentially no medical infrastructure. The higher figure assumes an intact hospital. Any prevalence/prognosis record here should carry the care context in population or notes, or the two numbers will look like a data error to a later reader.

Modifying factors — physical

Not all Grays are equal, and the entry should say so:

Dose rate. Same total dose delivered slowly is far less lethal; sublethal damage repair happens between hits.
Dose uniformity / partial-body sparing. This is enormous. Shielding even a small marrow volume changes the outcome completely — the standard preclinical GI-ARS model deliberately spares 5% of marrow precisely so the animal survives long enough to have a GI syndrome (Mitra et al., PMID:39930324: "13 Gy partial body X-irradiation with 5% bone marrow shielding").
Radiation quality / LET. Neutrons carry higher relative biological effectiveness than photons at equal absorbed dose. Royba et al. (PMID:35994701) found in the dicentric assay that "the frequency of dicentrics depends on the type of radiation" — which means dose estimation itself is quality-dependent.
Geometry — anteroposterior vs. rotational exposure changes marrow dose for the same free-in-air dose.

Modifying factors — host

Age. Children are more radiosensitive both acutely and for late effects (PMID:37280005). Elderly patients have less marrow reserve.
Pregnancy. Fetal exposure is a separate injury class (teratogenesis, growth restriction) beyond this entry's scope but relevant to triage.
Combined injury — the big one. Radiation plus burn or trauma is dramatically worse than either alone, and this is a real mechanistic interaction rather than additive risk. Kiang & Blakely (PMID:36947602) state: "At present, no FDA-approved drug to protect, mitigate, or treat CI is available." Glowacki et al. (PMID:34233299) confirm mouse models "show dose-dependent impairment of wound healing." This deserves its own pathophysiology node with EXACERBATES semantics, not a footnote.
Nutritional status, baseline marrow reserve, comorbid immunosuppression.
Microbiome composition — see §6; this turns out to be a genuine host modifier, not a curiosity.

Genetic risk factors

There is no causal gene. ARS is fully environmental. But germline DNA-repair defects are legitimate susceptibility modifiers, and the mechanism is clean: if you can't repair a double-strand break, the same physical dose becomes a larger biological dose.

Gene	HGNC	Syndrome	Radiosensitivity evidence
ATM	hgnc:795 ✅	Ataxia-telangiectasia (AR)	Homozygotes are clinically radiosensitive; literature reports a severe reaction at a dose as low as 3 Gy in an A-T patient. Amirifar et al. (PMID:32791865) describe A-T as "a rare autosomal recessive syndrome characterized by progressive cerebellar ataxia, oculocutaneous telangiectasia, variable immunodeficiency, radiosensitivity, and cancer predisposition."
NBN	hgnc:7652 ✅	Nijmegen breakage syndrome	"Lymphocytes and fibroblasts of NBS patients have been found to be hypersensitive to IR"
MRE11	hgnc:7230 ✅	ATLD (A-T–like disorder)	Later onset, milder than A-T, same radiosensitivity + chromosomal instability
PRKDC (DNA-PKcs)	hgnc:9413 ✅	NHEJ deficiency / RS-SCID	Core NHEJ kinase
LIG4	🔎 LEAD	LIG4 syndrome	Well-documented clinical radiosensitivity
TP53	hgnc:11998 ✅	Li-Fraumeni	Central to the apoptotic response; relevant to late-effect risk
DCLRE1C (Artemis), NHEJ1 (Cernunnos), Fanconi anemia genes	🔎 LEAD	RS-SCID, FA	FA is "characterized by childhood-onset aplastic anemia, cancer or leukemia susceptibility, and cellular hypersensitivity to DNA-crosslinking agents" — note the crosslinker sensitivity is the defining feature; IR sensitivity in FA is more variable and contested

The ATM heterozygote question is unsettled and should be curated as such. Carriers are roughly 1–2.5% of the population, and whether they have clinically meaningful intermediate radiosensitivity remains debated. Model this as a discussions entry with kind: KNOWLEDGE_GAP rather than asserting an effect.

Beyond single genes, radiogenomics — Story & Durante (PMID:30421807) define it as "the study of genomic changes that underlie the radioresponse of normal and tumor tissues" — is the field studying common-variant contributions to normal-tissue radiation toxicity. Almost all of it is radiotherapy-derived (fractionated, localized) and its transfer to single-fraction whole-body ARS is an inference, not a demonstration. Flag that explicitly if you use it.

Suggested inheritance modeling: no inheritance: block for the disease itself. Susceptibility genes go in genetic: with relationship_type: SUSCEPTIBILITY or MODIFIER. Do not use CAUSATIVE here — nothing in the genome causes ARS.

Protective factors

Physical, not biological, is where the real protection lives: time, distance, shielding; sheltering and evacuation; partial-body shielding of marrow.

Genetic protective factors: none established. 🔎 No published protective allele for ARS that I could find.

Pharmacological prophylaxis: none FDA-approved. Singh et al. (PMID:39160790) are explicit: "Currently, there is no radiation medical countermeasure approved by the U.S. FDA which can be used before radiation exposure to protect exposed individuals." Candidates in §12.

A distinction the entry must not blur: potassium iodide is not ARS prophylaxis. KI (CHEBI:8346 ✅) saturates the thyroid so inhaled/ingested radioiodine can't be taken up. It does nothing about external whole-body dose and nothing about marrow. Same for Prussian blue (cesium/thallium) and Ca-/Zn-DTPA (transuranics) — those are decorporation agents for internal contamination, a different disease process. Putting them in treatments: for ARS without a very clear scoping note is a modeling error I'd expect a reviewer to flag.

Gene–environment interaction

The core interaction is dose × DNA-repair capacity: identical physical dose produces a larger biological insult in a repair-deficient host, because unrejoined double-strand breaks are the substrate for cell death. That's the mechanistic through-line linking §2 and §6. Beyond the monogenic syndromes, GxE evidence for ARS specifically is thin — most of it is extrapolated from radiotherapy toxicity cohorts.

3. Phenotypes

The four-phase temporal architecture

Every ARS phenotype has to be anchored to a phase, or the entry will read as if these things happen at once. They don't. Arnautou & Garnier (PMID:39025400):

"This syndrome typically progresses through three stages with a prodromal phase, a latency phase and a critical phase. Each of them varies in intensity and duration depending on the absorbed dose of radiation."

Orphanet counts four: prodromal → latent → manifest illness → recovery or death. Use four; the recovery/death fork is a real branch. Higher dose compresses every phase — at very high dose the latent period disappears entirely, which is itself diagnostic.

Suggested progression: records (the phase field is the foreign-key target):

Phase	Timing	What happens
Prodromal	minutes–48 h	Nausea, vomiting, anorexia, sometimes diarrhea, fatigue, headache; possibly early transient erythema. Time-to-onset is dose-proportional.
Latent	days–~3 weeks (dose-dependent; absent at very high dose)	Patient feels well. Counts are falling. This is the window where dose assessment and countermeasure administration happen.
Manifest illness	~1–6 weeks (much sooner for GI)	Subsyndrome-specific: infection/hemorrhage (H), fluid loss/sepsis (GI), necrosis (cutaneous), coma (CNS).
Recovery or death	weeks–months	Marrow reconstitution, or death; survivors enter DEARE.

Prodromal phenotypes

Phenotype	HP term	Status	Notes
Nausea	`HP:0002018` Nausea	✅
Vomiting	`HP:0002013` Vomiting	✅	Time to emesis is the single best bedside dose proxy — see §10
Nausea and vomiting (composite)	`HP:0002017` Nausea and vomiting	✅
Diarrhea	`HP:0002014` Diarrhea	✅	Early diarrhea = high dose; `temporality: ACUTE`
Fatigue	`HP:0012378` Fatigue	✅
Headache	`HP:0002315` Headache	✅
Fever	`HP:0001945` Fever	✅	Early fever is a bad sign
Anorexia	🔎 LEAD (`HP:0002039` Anorexia — verify)	🔎

Frequency: near-universal above ~2 Gy. Prodromal nausea/vomiting is the CDC's and REMM's frontline triage sign precisely because it shows up in essentially everyone with a meaningful dose. Use frequency bands cautiously — I did not find a clean cohort denominator to cite, and per the repo's frequency-band guidance, a definitional-sounding statement is not a frequency.

Hematopoietic subsyndrome (H-ARS) — ≥ ~2 Gy

The dominant subsyndrome and the one every approved drug targets. Yamaga et al. (PMID:38333215) on the kinetics:

"Depending on the dose of ionizing radiation, death of hematopoietic stem and progenitor cells and apoptosis of lymphocytes occur, and lymphopenia becomes apparent within 6-24 hours after radiation exposure."

Phenotype	HP term	Status	Timing / notes
Decreased total lymphocyte count	`HP:0001888` (label: Decreased total lymphocyte count; syn. Lymphopenia)	✅ OLS4	6–24 h. Earliest measurable change. Lymphocytes die by interphase apoptosis without needing to divide
Decreased total neutrophil count	`HP:0001875` (syn. Neutropenia)	✅ OLS4	Nadir ~10–21 d
Decreased total leukocyte count	`HP:0001882` (syn. Leukopenia)	✅ OLS4
Thrombocytopenia	`HP:0001873`	✅	Nadir ~2–4 weeks; drives hemorrhage
Anemia	`HP:0001903`	✅	Latest to appear — RBC lifespan ~120 d
Pancytopenia	`HP:0001876`	✅	The composite; Orphanet's headline term
Aplastic anemia	`HP:0001915`	✅	For the irreversible (METREPOL H4) case
Bone marrow hypocellularity	`HP:0005528`	✅	The histopathologic finding
Petechiae	`HP:0000967`	✅	Thrombocytopenic bleeding
Sepsis	`HP:0100806`	✅	The proximate cause of most H-ARS deaths
Recurrent infections	`HP:0002719`	✅
Immunodeficiency	`HP:0002721`	✅
Gastrointestinal hemorrhage	`HP:0002239`	✅	Overlaps with GI subsyndrome
Epilation / alopecia	`HP:0001596` Alopecia	✅	~2–3 weeks; threshold ~3 Gy

Severity: dose-graded, from mild transient cytopenia to irreversible marrow failure. Progression: progressive to nadir, then either recovery or not — model as PROGRESSIVE through manifest illness. QoL: during aplasia, near-total functional dependence — protective isolation, transfusion dependence, high infection risk. Formal EQ-5D/SF-36 data for ARS specifically: 🔎 not found. Don't invent one.

Gastrointestinal subsyndrome (GI-ARS) — ≥ ~6 Gy

Winters & Marzella (PMID:38616048) on the consequence chain:

"Damage incurred in the latter can lead to nutrient malabsorption, dehydration, electrolyte imbalance, altered microbiome and metabolites, and impaired barrier function, which can lead to septicemia and death."

Phenotype	HP term	Status
Diarrhea (severe, often bloody)	`HP:0002014`	✅ — use `severity: SEVERE`
Malabsorption	`HP:0002024`	✅
Dehydration	`HP:0001944`	✅
Hypovolemic shock	`HP:0031274`	✅
Hypotension	`HP:0002615`	✅
Gastrointestinal hemorrhage	`HP:0002239`	✅
Weight loss	`HP:0001824`	✅
Sepsis / septicemia	`HP:0100806`	✅
Stomatitis / mucositis	`HP:0010280` Stomatitis	✅
Oral ulcer	`HP:0000155`	✅
Electrolyte imbalance	🔎 LEAD	—

Timing: onset within days; death typically 5–10 days at ≥10 Gy. Prognosis: without marrow support, uniformly fatal above ~10 Gy — GI-ARS is a concurrent syndrome, not a replacement, so the patient has a wrecked gut and no white cells at the same time. That combination is why bacterial translocation across a denuded barrier is so reliably lethal.

Cutaneous radiation syndrome (CRS)

Iddins et al. (PMID:34488201) frame it: "Cutaneous radiation injuries (CRI) or local radiation injuries (LRI) may lead to cutaneous radiation syndrome."

Manifestations, per the search literature: "skin damages, erythema, altered sensation, itching, edema, blistering, desquamation, ulcer, necrosis, hair loss, and onycholysis."

Phenotype	HP term	Status	Approx. skin-dose threshold
Erythema	`HP:0010783`	✅	~2–3 Gy (often biphasic — an early transient wave, then a later one)
Alopecia / epilation	`HP:0001596`	✅	~3 Gy
Abnormal blistering of the skin	`HP:0008066`	✅	~15–20 Gy (moist desquamation)
Skin erosion	`HP:0200041`	✅
Skin ulcer	`HP:0200042`	✅	~20–25 Gy
Abnormality of the skin (generic parent)	`HP:0000951`	✅
Dry desquamation, onycholysis, skin necrosis	🔎 LEAD	—	~10 Gy / ~25 Gy

⚠️ The dose thresholds in this table came from general secondary sources, not a single citable primary paper I verified. They're broadly consensus but you need a real citation per row before they go in as evidence-backed claims.

CRS is famously waves, not a single event — erythema recurs at intervals over weeks as successive cell populations fail, which is why it fools clinicians who expect a burn to behave like a burn. It's also the subsyndrome most likely to appear without whole-body ARS (industrial source handling), and the one most likely to demand surgery.

Neurovascular / cardiovascular / CNS subsyndrome — very high dose

"The neurovascular/cardiovascular/central nervous system syndrome occurs at doses >50 Gray and is characterized by watery diarrhea, convulsions, coma, and death within three days of exposure."

Phenotype	HP term	Status
Seizure	`HP:0001250`	✅
Coma	`HP:0001259`	✅
Confusion	`HP:0001289`	✅
Ataxia	`HP:0001251`	✅
Cerebral edema	`HP:0002181`	✅
Hypotension (refractory)	`HP:0002615`	✅
Cognitive impairment	`HP:0100543`	✅

Prognosis: universally fatal. There is no treatment; management is palliative. Note the dose threshold varies across sources (>20 Gy in some, >50 Gy in others) — 🔎 pin this to a specific citation rather than averaging.

Delayed effects (DEARE) — survivors

Wu & Orschell's DEARE work (PMID:37014943) documented in mice, after a sub-threshold H-ARS dose: "residual bone marrow damage (RBMD) and progressive renal and cardiovascular DEARE", plus "physiological and neural function, progressive fur graying, ocular inflammation, and malignancy."

Late phenotype	HP term	Status	Evidence
Renal insufficiency	`HP:0000083`	✅	Gasperetti et al. PMID:36688956 — rats >8 Gy show "a dose-dependent impairment of renal function as assessed by blood urea nitrogen (BUN) and urine protein to urine creatinine ratio"
Abnormal renal physiology	`HP:0012211`	✅	same
Pulmonary fibrosis	`HP:0002206`	✅	Rat PBI >12 Gy → pneumonitis days 50–100
Cataract	`HP:0000518`	✅	Classic late radiation effect (`UBERON:0000965` lens ✅)
Cardiomyopathy	`HP:0001638`	✅	Coronary rarefaction + endothelial loss in mouse DEARE
Leukemia	`HP:0001909`	✅	Thymic lymphoma in mouse models; leukemia in A-bomb survivors
Neoplasm	`HP:0002664`	✅	Solid tumors, long latency
Hypothyroidism	`HP:0000821`	✅
Male infertility / Azoospermia / Infertility	`HP:0003251` / `HP:0000027` / `HP:0000789`	✅	Spermatogonia are exquisitely radiosensitive
Xerostomia	`HP:0000217`	✅	Salivary gland involvement
Cognitive impairment	`HP:0100543`	✅	Behavioral DEARE demonstrated in mice — ⚠️ mouse data; human translation is a `HUMAN_MODEL_MISMATCH` candidate, not a settled human phenotype

Important curation note: most of the specific DEARE phenotype list is rodent-derived. The Ukrainian ARS survivor cohort (Belyi et al., PMID:20445398) is the human counterpart and covers "over 20 years of health outcomes among confirmed ARS survivors." Cite the human study for human claims; keep the mouse detail tagged MODEL_ORGANISM.

4. Genetic / Molecular Information

Causal genes: none

State this explicitly in the entry rather than leaving genetic: empty and ambiguous. ARS has no causal gene, no pathogenic variant class, no inheritance pattern, no penetrance, no carrier frequency, no founder effect, and no consanguinity role. Every one of those template fields is not applicable, and saying so is more useful than silence.

Somatic / acquired genomic change — the actual "genetics" of ARS

What radiation does to the genome is the disease:

DNA double-strand breaks — the lethal lesion. Huang & Zhou (PMID:32355263): "DNA double-strand breaks are the most lethal lesions induced by ionizing radiation."
Clustered/complex lesions — multiple damages within one or two helical turns, much harder to repair than isolated breaks. This is why high-LET radiation is disproportionately lethal.
Chromosomal aberrations — dicentrics, rings, translocations, micronuclei. These aren't just damage; they're the diagnostic assay (§10).

Genes as biodosimetry readout (not as cause)

This is the one place a gene list genuinely belongs in the entry — as biochemical: / BiomarkerReadout records, not as genetic: causal entries.

The canonical radiation-responsive transcript panel:

Gene	HGNC	Role
FDXR	hgnc:3642 ✅	The most-cited single transcriptional dosimeter
DDB2	hgnc:2718 ✅	DNA damage-binding, p53 target
MDM2	hgnc:6973 ✅	p53 autoregulatory loop
CDKN1A (p21)	🔎 LEAD	Cell-cycle arrest effector
AEN, BAX, BBC3 (PUMA), GADD45A, CCNG1, PCNA, ACTA2, ASCC3, WNT3, POU2AF1, ACTN1	🔎 LEAD	Rest of the reported panel

From the biodosimetry literature: "Specific radiation-sensitive genes such as FDXR, DDB2, WNT3, and POU2AF1 have become well established for biodosimetry purposes and acute radiation sickness prediction, with FDXR and DDB2 commonly used as biomarkers for retrospective dosimetry within 72 hours after radiation exposure."

At the protein level: "When combining FDXR, ACTN1, and DDB2 proteins to estimate radiation dose by linear regression, the combination showed the lowest mean absolute errors (≤0.13 Gy) and highest coefficients of determination (R² = 0.96)." ⚠️ Verify this against the primary paper before quoting — it came through a search-result layer, not efetch.

Mechanism-relevant genes (for pathophysiology node binding)

Gene	HGNC	Where it sits in the chain
ATM	hgnc:795 ✅	Apical DSB kinase. Also, unexpectedly, a ferroptosis regulator — Wu et al. (PMID:36752571) show ATM "phosphorylat[es] NCOA4" to control ferritinophagy, "largely independently of p53 downstream signaling"
PRKDC	hgnc:9413 ✅	NHEJ catalytic subunit
NBN, MRE11	hgnc:7652, hgnc:7230 ✅	MRN complex, break sensing
TP53	hgnc:11998 ✅	The apoptosis/arrest decision node
SMPD1 (acid sphingomyelinase)	hgnc:11120 ✅	The ceramide arm. ASMase-null mice are protected from GI syndrome
MPL	hgnc:7217 ✅	TPO receptor — romiplostim's target
CSF2 (GM-CSF)	hgnc:2434 ✅	Sargramostim's ligand
CSF3 (G-CSF)	🔎 LEAD	Filgrastim/pegfilgrastim
HMGB1	hgnc:4983 ✅	Prototype DAMP
NLRP3	hgnc:16400 ✅	Inflammasome; upregulated post-TBI in minipig ileum
IL1B, TNF	hgnc:5992, hgnc:11892 ✅	Cytokine amplification
YAP1	hgnc:16262 ✅	Revival stem cell program
GPX4, SLC7A11	🔎 LEAD	Ferroptosis axis — both downregulated post-irradiation in minipig ileum (PMID:38674120)
LGR5, CLU	🔎 LEAD	Crypt base columnar ISC marker; revival SC marker

Epigenetics

Radiation-induced methylation and chromatin changes are reported in the multi-omics literature (Shakyawar et al., PMID:36368026, catalogs "radiation-induced changes across genomic, transcriptomic, proteomic, metabolomic, and microbiome profiles"), but I found no ARS-specific epigenetic mechanism with the evidentiary weight to be a pathophysiology node. 🔎 Treat as an open area, not a claim.

Chromosomal abnormalities

Acquired only: dicentric chromosomes (the biodosimetry gold standard), rings, reciprocal translocations (persistent — used for retrospective dosimetry years later), and micronuclei. None germline.

5. Environmental Information

This section is the etiology, so it carries most of the entry's causal weight. See §2 for the full scenario list.

Environmental factor to model:

environmental:
- name: Acute whole-body exposure to penetrating ionizing radiation
  exposure_term:
    preferred_term: acute whole-body exposure to penetrating ionizing radiation
    term:
      id: ECTO:7000047          # ✅ VERIFIED
      label: exposure to ionizing radiation
  influences_mechanisms:
  - target: <the DNA damage / energy deposition node>
    environmental_effect: TRIGGERS
    causal_link_type: DIRECT

Note the preferred_term is deliberately more specific than the ECTO label — that's exactly the pattern the repo's ontology contract endorses, since ECTO has no term for the acute high-dose-rate whole-body case.

Lifestyle factors: essentially none. Occupation is the real exposure axis (nuclear workers, industrial radiographers, radiotherapy staff, emergency responders, military). Smoking/diet/alcohol are not established modifiers of acute radiation lethality.

Infectious agents: not causal — but bacteria are absolutely part of the mechanism. The killing blow in both H-ARS and GI-ARS is usually endogenous bacterial translocation across a failed gut barrier into a host with no neutrophils. Yamaga et al. (PMID:38333215) name it: "lethal sepsis stands as a major contributor to the mortality in ARS." So the microbiome belongs in the pathograph, and the relevant taxa are commensals gone rogue rather than an outside pathogen.

Gut microbiome as a bidirectional modifier — genuinely one of the most interesting recent developments, covered in §6.

6. Mechanism / Pathophysiology

The causal chain, step by step

Here's the spine. Branches are marked. Where a step is inferred rather than demonstrated in humans, I say so.

Step 0 — Energy deposition. An ionizing photon or particle traverses tissue and deposits energy, both by directly ionizing macromolecules and — for about two-thirds of low-LET damage — by radiolysis of water, generating hydroxyl radicals, superoxide, and hydrogen peroxide. → leads to

Step 1 — Clustered DNA lesions, especially double-strand breaks. DSBs are the lethal lesion (PMID:32355263). Base damage and single-strand breaks are mostly repaired; complex clustered damage is not. → leads to

Step 2 — DNA damage response activation. MRN complex senses the break; ATM (and ATR, DNA-PKcs) phosphorylate H2AX and downstream substrates; CHK1/CHK2 relay; TP53 is stabilized. → branches into three fates: - 2a — Repair and survive. NHEJ or homologous recombination rejoins the break; cell cycle resumes. - 2b — Arrest / senescence. p53 → CDKN1A/p21 → durable arrest. GO:0090398 cellular senescence ✅ — observed as p21/waf1 upregulation in irradiated minipig ileum (PMID:38674120). - 2c — Death. p53 → BAX/PUMA → mitochondrial outer membrane permeabilization → intrinsic apoptosis (GO:0008630 ✅). Or, for cells that attempt to divide with unrepaired breaks, mitotic catastrophe — which is why proliferating compartments are hit hardest.

Step 3 (parallel arm, not downstream of Step 2) — the membrane/ceramide pathway. This one is important and easy to model wrong. Radiation triggers translocation of secretory acid sphingomyelinase (SMPD1) into cholesterol/glycosphingolipid rafts of the outer plasma membrane leaflet, where sphingomyelin is hydrolyzed to ceramide, which coordinates transmembrane apoptotic signaling. This happens within hours and does not require nuclear DNA damage signaling — it's a parallel initiating lesion, and if you draw it downstream of p53 you've inverted the biology.

From Paris et al. and the anti-ceramide follow-up work: "Extensive endothelial cell apoptosis occurred in the first 4 hours after administering radiation doses sufficient for inducing the GI syndrome (≥15 Gy), while epithelial cell apoptosis occurred several hours after endothelial cell death." And the causal test: "Genetic inactivation of ASMase in mice, or intravenous treatment with the endothelial cell survival factor bFGF prior to whole body irradiation, attenuated radiation-induced endothelial apoptosis of the intestinal microvascular system, preserved crypt stem cell clonogens, and protected mice against lethality from the GI syndrome."

⚠️ This is MODEL_ORGANISM evidence and the endothelial-first model has been contested in the field. Curate it as the leading mechanism with an explicit discussions entry noting the debate, not as settled fact.

Step 4 — Selective destruction of self-renewing compartments. The tissues that lose are the ones that must constantly rebuild: hematopoietic stem/progenitor cells, intestinal crypt stem cells, basal keratinocytes and follicular stem cells, spermatogonia. Plus lymphocytes, which are the exception that proves the rule — they die by interphase apoptosis without dividing, which is why lymphopenia is the earliest signal. → branches into the four subsyndromes

Branch A — Hematopoietic ARS (≥ ~2 Gy)

4A.1 HSPC apoptosis + mitotic death, plus damage to the bone marrow niche itself — endothelial and mesenchymal stromal cells, not just the stem cells. This is a relatively recent refinement and matters therapeutically. Vercellino et al. (PMID:38679747) established that a thrombopoietin mimetic works partly through the niche: "TPOm interacts with BM vascular and stromal niches to locally support hematopoietic reconstitution and systemically improve survival in mice after TBI." → leads to

4A.2 Loss of proliferative reserve. Nothing dramatic happens yet — this is the latent phase. → leads to

4A.3 Sequential cytopenias as each mature lineage runs out on its own clock: lymphocytes 6–24 h, neutrophils ~10–21 d, platelets ~2–4 wk, red cells latest. → leads to

4A.4 Two convergent failure modes — infection (no neutrophils + breached mucosal barriers) and hemorrhage (no platelets). → leads to

4A.5 Sepsis, multi-organ failure, death. Or, with support and cytokines, marrow reconstitution and recovery.

Branch B — Gastrointestinal ARS (≥ ~6 Gy)

4B.1 Endothelial apoptosis in the lamina propria microvasculature (Step 3) plus direct crypt stem cell clonogen death. → leads to

4B.2 Crypt depopulation. → leads to

4B.3 Villus denudation — enterocytes continue their normal migration up the villus and slough off, and nothing arrives to replace them. Takes ~3–5 days, which sets the syndrome's timing. → leads to

4B.4 Barrier failure + massive fluid/electrolyte loss + malabsorption. → leads to

4B.5 Dysbiosis and bacterial translocation, DAMP release, cytokine amplification. Freeman (PMID:40368913): the field's priorities are "Understanding intestinal stem cell contributions to recovery, vascular damage mechanisms, and crypt-villus regeneration following irradiation." → converges with 4A.4 →

4B.6 Septicemia and death, typically 5–10 days.

The regeneration counter-branch — genuinely exciting recent biology, and the reason GI-ARS may become treatable: - Revival stem cells (revSC) — Ayyaz et al. (PMID:31019301) identified "a distinct, damage-induced quiescent cell type that we term the revival stem cell (revSC)", marked by high clusterin, "extremely rare under homoeostatic conditions," which "reconstitute the LGR5+ CBC compartment and are required to regenerate a functional intestine" via YAP1. - Tuft cells as a human reserve pool — Huang et al. (PMID:39358509): "tuft cells survive irradiation damage and retain the ability to generate all other epithelial cell types," representing "a damage-induced reserve intestinal stem cell pool in humans." Human tissue evidence, which is rare here — weight it accordingly. - Isthmus progenitors — Malagola et al. (PMID:38848678) argue stemness "resides in the isthmus region" and that "neither de-differentiation nor reserve ISC are drivers of intestinal regeneration." ⚠️ This directly contradicts the revSC model. That's a real live controversy and belongs in mechanistic_hypotheses with competing hypothesis_group_ids, not resolved by fiat. - Niche signals — macrophages drive repair via NRG1 and osteopontin, and "macrophage ablation led to compromised regeneration" (PMID:40086603); a tissue-intrinsic IL-33/EGF circuit promotes epithelial regeneration (PMID:37669929).

Branch C — Cutaneous radiation syndrome

4C.1 Basal keratinocyte and hair-follicle stem cell death + dermal microvascular endothelial injury. → 4C.2 epilation, erythema in waves, dry then moist desquamation, blistering. → 4C.3 at higher dose, ulceration and necrosis, often requiring surgery. → 4C.4 late dermal fibrosis.

When CRS coexists with whole-body dose, you get radiation combined injury, where wound healing is itself radiation-impaired — a vicious circle with no approved therapy (PMID:36947602).

Branch D — Neurovascular / CNS syndrome (very high dose)

4D.1 Overwhelming endothelial death and vascular permeability + direct neuronal/glial damage. → 4D.2 cerebral edema, refractory hypotension. → 4D.3 prostration, ataxia, convulsions, coma. → 4D.4 death within ~3 days. Gorbunov & Kiang (PMID:33979447) note "cranial or total-body irradiation can cause a plethora of biochemical and cellular disorders in brain tissues."

Step 5 — Systemic amplification via DAMPs. Yamaga et al. (PMID:38333215) describe the loop: radiation causes cellular injury through DNA damage and oxidative stress, prompting DAMP release; these molecules then "interact with pattern recognition receptors, triggering inflammatory responses"; and "lethal sepsis stands as a major contributor to the mortality in ARS." This makes the syndromes non-independent — GI barrier failure feeds the systemic inflammation that worsens everything else. Radiation-induced multi-organ dysfunction syndrome is the terminal common path.

Step 6 — DEARE in survivors (months to years): residual bone marrow damage, progressive renal failure, pneumonitis→fibrosis, cardiovascular rarefaction and senescence, cataract, cognitive/behavioral change, secondary malignancy.

The microbiome layer — a real modifier, not decoration

This deserves its own treatment because the evidence is now strong enough to model.

Guo et al., Science 2020 (PMID:33122357) — the "elite survivor" study. Mice that survived high-dose radiation to live normal lifespans harbored "distinct gut microbiota that developed after radiation and protected against radiation-induced damage and death." Elevated Lachnospiraceae and Enterococcaceae correlated with restored hematopoiesis and GI repair, and — critically — "these bacteria were also found to be more abundant in leukemia patients undergoing radiotherapy, who also displayed milder gastrointestinal dysfunction", which is the human anchor. On the metabolite side: "Metabolomics revealed increased fecal concentrations of microbially derived propionate and tryptophan metabolites," and administering those metabolites "caused long-term radioprotection."

Supporting metabolite work: - Propionate (CHEBI:17272 ✅) and butyrate (CHEBI:17968 ✅) — short-chain fatty acids. - Valeric acid — Li et al. (PMID:31931652): "VA exerted the most significant radioprotection among the SCFAs." - Indole-3-carboxaldehyde (I3A) — Xie et al. (PMID:38706205): I3A "activated the AhR/IL-10/Wnt signaling pathway to promote intestinal epithelial proliferation." - Contrarily, Jiao et al. (PMID:40192235) found raffinose-metabolizing bacteria impair hematopoietic recovery via bile acid/FXR/NF-κB — so it cuts both ways. - And Cook et al. (PMID:36253079) found that antibiotic microbiome depletion did not protect against radiation carcinogenesis and actually "shortened the lifespan when Ab were administered before and after TBI" — a useful REFUTE-direction evidence item against naive "just sterilize the gut" reasoning.

Cell death modes beyond apoptosis

Ferroptosis is now implicated. Horseman et al. in the Göttingen minipig (PMID:38674120): "GPX-4 and SLC7A11 were downregulated post-irradiation, consistent with ferroptosis at 6 and 35 days post-irradiation in all groups." And the ATM–NCOA4–ferritinophagy link (PMID:36752571) connects the DDR kinase directly to iron-dependent death. Also relevant: necroptosis, autophagy, and pyroptosis via NLRP3 — the minipig study found radiation increased "IL1B, TNFA, CCL2, IL18, and CXCL8, and the inflammasome component NLRP3."

Suggested GO / CL bindings for pathophysiology nodes

Biological processes — all ✅ VERIFIED against cache/go/terms.csv:

GO ID	Label	Node it fits
`GO:0006974`	DNA damage response	Step 2
`GO:0006281`	DNA repair	Step 2a
`GO:0006302`	double-strand break repair	Step 2a
`GO:0072331`	signal transduction by p53 class mediator	Step 2
`GO:0008630`	intrinsic apoptotic signaling pathway in response to DNA damage	Step 2c
`GO:0006915`	apoptotic process	Steps 2c, 4A.1
`GO:0006685`	sphingomyelin catabolic process	Step 3 — `modifier: INCREASED`
`GO:0046513`	ceramide biosynthetic process	Step 3 — `modifier: INCREASED`
`GO:0072577`	endothelial cell apoptotic process	Step 3 / 4B.1 — `modifier: INCREASED`
`GO:0006979`	response to oxidative stress	Step 0/1
`GO:0072593`	reactive oxygen species metabolic process	Step 0
`GO:0090398`	cellular senescence	Step 2b
`GO:0097707`	ferroptosis	alternate death mode
`GO:0070266`	necroptotic process	alternate death mode
`GO:0006914`	autophagy	ferritinophagy arm
`GO:0006954`	inflammatory response	Step 5
`GO:0045087`	innate immune response	Step 5
`GO:0019221`	cytokine-mediated signaling pathway	Step 5
`GO:0071425`	hematopoietic stem cell proliferation	4A.2 — `modifier: DECREASED`
`GO:0030099`	myeloid cell differentiation	4A.3 — `modifier: DECREASED`
`GO:0030219`	megakaryocyte differentiation	4A.3 — `modifier: DECREASED`
`GO:0038163`	thrombopoietin-mediated signaling pathway	romiplostim target
`GO:0050673`	epithelial cell proliferation	4B.2 — `modifier: DECREASED`
`GO:0016055`	Wnt signaling pathway	crypt regeneration
`GO:0001525`	angiogenesis	niche recovery
`GO:0051882`	mitochondrial depolarization	Step 2c

On modifier choice: most of these are genuinely INCREASED/DECREASED (quantitative), and per the repo's guidance that's the default. Don't reach for LOSS_OF_FUNCTION — nothing here is escaping regulatory control; things are simply running above or below normal.

Cell types — all ✅ VERIFIED against cache/cl/terms.csv:

CL:0000037 hematopoietic stem cell · CL:0000049 common myeloid progenitor · CL:0000557 granulocyte monocyte progenitor cell · CL:0000556 megakaryocyte · CL:0000775 neutrophil · CL:0000542 lymphocyte · CL:0000084 T cell · CL:0000236 B cell · CL:0000115 endothelial cell · CL:0002139 endothelial cell of vascular tree · CL:0002250 intestinal crypt stem cell · CL:0002563 intestinal epithelial cell · CL:0000584 enterocyte · CL:0000510 paneth cell · CL:0002253 epithelial cell of large intestine · CL:0000312 keratinocyte · CL:0002559 hair follicle cell · CL:0000134 mesenchymal stem cell · CL:0000235 macrophage · CL:0000216 Sertoli cell · CL:0000023 oocyte

🔎 LEAD: tuft cell, revival stem cell (no CL term likely exists — use preferred_term and leave term: off rather than binding something wrong).

Chemical entities — ✅ VERIFIED: CHEBI:17761 ceramide · CHEBI:26523 reactive oxygen species · CHEBI:16240 hydrogen peroxide · CHEBI:15379 dioxygen · CHEBI:17272 propionate · CHEBI:17968 butyrate 🔎 LEAD: hydroxyl radical, superoxide, indole-3-carbaldehyde, valerate/pentanoate.

Molecular profiling

Transcriptomics — the biodosimetry panels above; single-cell RNA-seq of the irradiated marrow niche (PMID:38679747) and regenerating intestine (PMID:31019301, PMID:38848678).
Proteomics — FDXR/ACTN1/DDB2 plasma panel; a "plasma proteomic biodosimetry approach based on a panel of radiation-responsive biomarkers" for combined injury (PMID:36947602).
Metabolomics — SCFAs, tryptophan/indole metabolites, bile acids.
Microbiome — 16S and shotgun profiling across mouse, minipig, and human radiotherapy cohorts.
Multi-omics integration — Shakyawar et al. (PMID:36368026): "multi-omic profiles obtained from high-resolution omics platforms offer a holistic approach" for identifying organ-specific damage biomarkers.
Single-cell — see above. Spatial transcriptomics and CRISPR screens for ARS specifically: 🔎 not found in this sweep.

Datasets: I did not run just discover-datasets. Do that before adding any datasets: block, and remember the relevance-triage warning — searching "radiation" or a DDR gene will surface a mountain of radiotherapy and cancer datasets that resolve perfectly and have nothing to do with ARS. That's Named Entity Confusion reached through dataset search, and it's a live risk here more than for most diseases.

7. Anatomical Structures Affected

Organ level

Primary (in rough order of radiosensitivity):

Structure	UBERON	Status
Bone marrow	`UBERON:0002371`	✅
Small intestine	`UBERON:0002108`	✅
Ileum	`UBERON:0002116`	✅
Jejunum	`UBERON:0002115`	✅
Duodenum	`UBERON:0002114`	✅
Colon	`UBERON:0001155`	✅
Skin of body	`UBERON:0002097`	✅
Hair follicle	`UBERON:0002073`	✅
Thymus	`UBERON:0002370`	✅
Spleen	`UBERON:0002106`	✅
Gonad / testis / ovary	`UBERON:0000991` / `UBERON:0000473` / `UBERON:0000992`	✅
Blood	`UBERON:0000178`	✅

Secondary / late (DEARE): lung UBERON:0002048 ✅ · kidney UBERON:0002113 ✅ · brain UBERON:0000955 ✅ · central nervous system UBERON:0001017 ✅ · lens of camera-type eye UBERON:0000965 ✅ · thyroid gland UBERON:0002046 ✅. 🔎 LEAD: heart, oral mucosa, salivary gland, vasculature/microcirculation.

Body systems: hematopoietic/immune, gastrointestinal, integumentary, reproductive, then cardiovascular, respiratory, renal, and nervous late.

Tissue and cell level

Epithelium (intestinal, epidermal, follicular), hematopoietic tissue, vascular endothelium, and lymphoid tissue. The cell list is in §6. The organizing principle worth stating in the entry's prose: radiosensitivity tracks proliferative rate (the old Bergonié–Tribondeau observation), with lymphocytes as the glaring exception — they're radiosensitive despite being quiescent, because they're primed for apoptosis.

Subcellular level

Nucleus / chromosome — the DSB target. 🔎 LEAD: GO:0005634 nucleus, GO:0005694 chromosome (verify).
Plasma membrane lipid rafts — the ASMase/ceramide platform, and the reason the membrane is a second independent target rather than an afterthought. 🔎 LEAD: GO:0045121 membrane raft (verify).
Mitochondrion — MOMP, ROS amplification, GO:0051882 mitochondrial depolarization ✅.
Lysosome — ferritinophagy/autophagy arm.

Localization / lateralization

Bilateral and systemic by definition for whole-body exposure. The clinically important exception is partial-body exposure, which is common in real accidents (a worker holding a source) and produces asymmetric, geometry-dependent injury: severe local cutaneous/deep-tissue damage over the exposed area with relative marrow sparing elsewhere. This isn't a footnote — partial-body geometry is the thing that determines whether biodosimetry estimates are even interpretable, and it's why the field built assays that can distinguish partial- from total-body exposure.

8. Temporal Development

Onset

Age: any. Not congenital, not age-dependent — it's whenever the exposure happens. Occupational cases skew adult; mass-casualty scenarios include all ages, with children at higher risk per unit dose.

Pattern: acute, sharply. temporality: ACUTE is the right qualifier throughout. Prodromal symptoms begin within minutes to 48 hours; the entire syndrome is defined by a single point-source exposure.

Progression and the phase structure

Covered in §3, but the two things worth restating for a progression: block:

Higher dose compresses everything. The latent period shortens and eventually disappears; time-to-emesis shortens; time-to-death shortens. The phase structure is dose-parameterized, not fixed.
The subsyndromes are concurrent, not sequential. At 8 Gy a patient has H-ARS and GI-ARS and CRS simultaneously. Modeling them as stages would be wrong. MacVittie & Farese's framing (PMID:32868706) — "concomitant multiple organ injury" — is the right one.

Duration: self-limited in one direction or the other within weeks, then either full recovery, recovery-with-DEARE (lifelong), or death.

Critical intervention windows — the actionable part

Window	Why it matters
0–6 h	Time-to-emesis observation; decontamination; first CBC for the lymphocyte baseline; blood draw for cytogenetics before transfusion
First 24 h	Cytokine administration — this is the window every approved MCM was tested in. Romiplostim, TPOm, and pegfilgrastim efficacy studies all dose at ~24 h post-exposure
First 48 h	Serial CBC q6h for lymphocyte depletion kinetics; HLA typing while lymphocytes still exist
≤72 h	Transcriptional biodosimetry validity window (FDXR/DDB2)
~3 weeks	The HSCT decision point. Arnautou & Garnier: transplant "will be carefully considered on an individual basis, especially for patients who do not respond following 3 weeks of cytokine therapy"
Months–years	DEARE surveillance; no approved DEARE countermeasure exists

There's a real asymmetry here that the entry should capture: the drugs work if given early, and the diagnostics work if sampled early, but the patient feels fine during exactly that window. The latent phase is a trap, and it's the single most operationally important fact about this disease.

Remission

Recovery is treatment-assisted, not spontaneous above ~2 Gy — marrow reconstitution from surviving stem cells, accelerated by cytokines. Below ~2 Gy, spontaneous recovery is the norm. Above ~12 Gy, neither happens.

9. Inheritance and Population

Inheritance

Not applicable. No inheritance pattern, penetrance, expressivity, anticipation, mosaicism, founder effect, consanguinity role, or carrier frequency. Say so explicitly.

Epidemiology

Orphanet prevalence: 1–9 per 1,000,000. That maps to prevalence_class: BAND_1_9_PER_1000000 and a rate_per_100000 of roughly 0.1–0.9 — though honestly a "prevalence" for an accident-driven condition is a strange quantity, and the notes: field should say that plainly. It's a rare-disease registry artifact more than an epidemiological measurement.

Cumulative human experience (the more meaningful figure), from Lazarus & Gale (PMID:40074513):

"Radiological accidents/incidents are common with nearly 400 reported since 1944 exposing about 3000 people to substantial doses of ionizing radiations with 127 deaths."

Chernobyl — the reference case series. From Belyi et al. (PMID:20445398): "134 of those were confirmed, including 28 patients who died due to lethal total-body gamma-irradiation." The fuller picture from IAEA/WNA sources: 237 initially suspected, 134 confirmed by 1989, doses 0.8–16 Gy, 28 deaths within 11 to 96 days, and a further 19 deaths 1987–2004 from causes not necessarily radiation-attributable.

Goiânia, 1987 — a Cs-137 teletherapy source opened in a scrapyard: ~250 people contaminated, 4 deaths from ARS. The definitive account is the IAEA's The Radiological Accident in Goiânia.

Tokaimura, 1999 — criticality accident at a uranium conversion plant, 2 worker deaths, 436 people dose-assessed.

Hiroshima/Nagasaki, 1945 — the largest dataset, but combined injury throughout.

REAC/TS registry inclusion criteria (useful for understanding what "a case" means): ≥250 mSv to whole body/marrow/gonads, ≥6,000 mSv to skin of extremities, ≥750 mSv to eye or thyroid, or internal contamination above half the maximum permissible body burden.

Demographics

Sex ratio: no biological sex difference in radiosensitivity is well established for ARS. Observed case series skew male because of occupational composition, not biology. ⚠️ Don't record a sex ratio as a disease property.
Geographic distribution: wherever sources and reactors are. Historical clusters follow accidents, not populations.
Age: children more sensitive; occupational cases adult.
Ethnicity: no established difference.

10. Diagnostics

ARS has an unusual diagnostic problem: there is no confirmatory test that's fast, and the fast tests aren't confirmatory. So triage runs on clinical kinetics while the real dosimetry catches up.

Clinical dose assessment — the frontline

Time to emesis. From the REMM/AFRRI guidance: "For time to emesis less than 4 hours, the effective whole-body dose is likely to be at least 3.5 Gy" and "If time to emesis is less than 1 hour, the whole-body dose probably exceeds 6.5 Gy, and a very complicated and likely fatal medical course may be expected."

Lymphocyte depletion kinetics. Serial absolute lymphocyte counts, ideally q6h for 48 h. The rule of thumb: "if within the first two days of exposure, lymphocytes have decreased by 50% and are less than 1000 cells per μL, the patient has received at least a moderate dose." Two formal models exist — the Andrews Lymphocyte Nomogram and the Goans exponential-decline model (see PMID:17993851, "Estimating radiation dose from time to emesis and lymphocyte depletion").

METREPOL response categories — the structured severity system, and a natural fit for a dismech definitions: entry with definition_type: PHENOTYPE_ALGORITHM and derivation_basis: ESTABLISHED_CRITERIA. It grades four organ systems separately — H (hematologic), N (neurovascular), C (cutaneous), G (gastrointestinal) — each on a 1–4 scale, and "identifies the likelihood of 'irreversible' (H4), and 'reversible' (H3, H2, and H1) damage to the bone marrow", linking the four to predict multiorgan failure. Lebaron-Jacobs & Herrera-Reyes (PMID:34801995) revisited it 20 years on, asking "if proposed criteria are still relevant for the medical management of radiation-induced injuries" — so treat it as established-but-under-review, with validation_status.status: UNVALIDATED unless you find a validation study.

Biodosimetry — the confirmatory layer

Dicentric chromosome assay (DCA) — the gold standard. Jeong et al. (PMID:36543843): "The dicentric chromosome assay is the 'gold standard' in biodosimetry for estimating radiation exposure." Its weakness is throughput: it needs a 48-hour lymphocyte culture and manual scoring, which is fine for one patient and hopeless for ten thousand.

The whole recent field is about fixing that: - RENEB inter-laboratory comparison 2021 (Endesfelder et al., PMID:37018160): "In total 33 laboratories from 22 countries around the world participated", with all participants successfully classifying extreme doses into clinically relevant exposure groups. This is the network that would actually run a mass-casualty response. - RABiT-II high-throughput DCA (Royba et al., PMID:35994701) — automated, validated under complex exposures including mixed fields. - Deep-learning automated scoring (PMID:36543843, PMID:38687685) — "particularly advantageous in scenarios such as large-scale radiological incidents." - G0-PCC (premature chromosome condensation) multiwell assay (PMID:38854157): "Our method can address the need for a same-day cytogenetic biodosimetry test in radiation emergency situations." Same-day is the goal.

Other cytogenetics: cytokinesis-block micronucleus assay (faster, less specific); FISH translocation painting (for retrospective dose years later); ring chromosomes.

Transcriptional/protein biodosimetry: the FDXR/DDB2/CDKN1A/AEN qPCR panels (§4), valid within ~72 h. Machine-learning combinations — e.g. ACTN1 + DDB2 + FDXR plus B and T cell counts — can "quantify and distinguish between partial-body irradiation and total-body irradiation exposures", which no single marker does.

Physical dosimetry: personal dosimeters where worn; EPR spectroscopy of tooth enamel, fingernails, or toenails; OSL of personal electronics; activation analysis (Na-24 in blood) for neutron exposure.

The NIAID program overview is Satyamitra et al. (PMID:37742625), "The NIAID/RNCP Biodosimetry Program: An Overview."

Routine clinical workup

CBC with differential q6h × 48 h then daily; comprehensive metabolic panel; serum amylase (rises with salivary gland dose); C-reactive protein; blood/urine/stool cultures; HLA typing early (do it while there are still lymphocytes to type); type and screen. Imaging as clinically indicated. Skin photography with serial documentation and mapping for CRS. Biopsy is rarely needed for diagnosis but marrow biopsy documents hypocellularity.

LOINC-coded lab observations for a biochemical: block: absolute lymphocyte count, absolute neutrophil count, platelet count, hemoglobin. 🔎 I did not resolve specific LOINC codes — look them up rather than guessing, and note the repo's memory that LOINC does not carry reference ranges as a field.

Genetic testing

Not applicable for diagnosis. ARS is not a genetic disease. Genetic testing has one narrow role: if a patient shows radiation toxicity grossly disproportionate to estimated dose, consider a DNA-repair-deficiency syndrome (ATM, NBN, LIG4, etc.) — that's a rare-but-real scenario and worth a sentence, not a section. WGS/WES/panels/CMA/karyotype/FISH/mtDNA/repeat expansion: all not applicable. (Note the irony that karyotyping is central here — just as a dosimeter, not a genetic test.)

Differential diagnosis

This is where ARS actually gets missed, because a patient with nausea, vomiting, and falling counts and no exposure history looks like ten other things. Ebeling et al. built a whole simulation curriculum around exactly this (PMID:37538304): "ARS is a high-risk, low-frequency diagnosis that can be fatal and is difficult to diagnose without an obvious history of ionizing radiation exposure."

Differential	Distinguishing feature
Viral gastroenteritis / food poisoning	No progressive lymphopenia; no dicentrics
Chemotherapy toxicity / drug-induced marrow suppression	Drug history; different cytopenia kinetics
Idiopathic aplastic anemia	Insidious onset; no prodrome; no exposure
Sepsis from another source	Cultures; no cytogenetic damage
Thrombotic thrombocytopenic purpura	Schistocytes, ADAMTS13
Thermal or chemical burn	CRS is delayed, recurs in waves, and doesn't match a contact pattern
Acute leukemia	Blasts on smear/marrow

The tell that separates ARS from all of them is the combination of a compressed prodrome, a deceptively well latent period, dose-proportional lymphocyte decline, and dicentric chromosomes. Nothing else does all four.

Screening

No population screening — there's no pre-symptomatic state to screen for. "Screening" in the ARS context means mass-casualty triage biodosimetry: rapidly sorting thousands of worried-well from the genuinely exposed. That's the entire design driver behind RABiT-II, the G0-PCC assay, and the qPCR panels.

11. Outcome / Prognosis

Survival

Prognosis is a nearly pure function of dose, medical care, and combined injury.

Dose band	Expected course
<1 Gy	Minimal to no clinical effect; "Radiation doses below 2 Gray generally result in insignificant clinical consequences" (PMID:39025400)
1–2 Gy	Mild prodrome, mild cytopenia, recovery expected
2–6 Gy	H-ARS; survivable with aggressive supportive care + cytokines; mortality climbs steeply with dose
6–10 Gy	H-ARS + GI-ARS; survival possible at the low end with maximal care, poor at the high end
10–12 Gy	Very poor; GI-ARS typically fatal within ~10 days
>12 Gy	"exceeds current therapeutic capacities" (PMID:39025400)
>20–50 Gy	Neurovascular syndrome; uniformly fatal within days

Human LD50/60: ~2.7–3.1 Gy marrow dose without medical care (A-bomb data, DS02); commonly quoted as ~4.5 Gy with modern care, though as noted in §2 that higher figure is soft.

NHP LD50/60 with medical management: 7.52 Gy (Farese et al., PMID:22929469): "The study defined an LD30/60 of 7.06 Gy, LD50/60 of 7.52 Gy, and an LD70/60 of 7.99 Gy." ⚠️ Do not present this as a human number — the macaque with full supportive care is roughly twice as tolerant as an unsupported human, and conflating the two is an easy and serious error.

Cause of death: in H-ARS, infection and hemorrhage during aplasia. In GI-ARS, sepsis from bacterial translocation plus fluid/electrolyte collapse. In CNS syndrome, cerebral edema and cardiovascular collapse.

Morbidity and function

Survivors face DEARE — progressive renal impairment, pulmonary fibrosis, cardiovascular disease, cataract, endocrine dysfunction, infertility, cognitive/behavioral change, and elevated cancer risk. Gasperetti et al. (PMID:36688956) drive the point home: "These data show survivors of H-ARS are at risk for the development of delayed renal toxicity and emphasize the need for the development of medical countermeasures for delayed renal injury." The Ukrainian ARS survivor cohort (PMID:20445398) is the long human record.

There's a structural irony worth writing into the entry: as H-ARS treatment improves, DEARE becomes a bigger problem, because more people survive to develop it. Wu et al. (PMID:37014943) note that "while effective medical countermeasures (MCM) for the hematopoietic-acute radiation syndrome (H-ARS) have been identified and approved by the FDA, development of MCM for DEARE has not yet been successful." We got good at the first act and never wrote the second.

QoL instruments: 🔎 No ARS-specific validated instrument found. EQ-5D/SF-36/PROMIS data for this population: not located.

Prognostic factors

Absorbed dose and its uniformity; time to emesis; lymphocyte depletion slope; METREPOL response category (especially H4 = irreversible marrow damage); presence of combined injury (major adverse factor); age; comorbidity; internal contamination; time from exposure to cytokine administration.

Prognostic biomarkers: dicentric frequency; ALC nadir and slope; the FDXR/DDB2 transcript panel; 🔎 candidate protein panels not yet clinically qualified.

12. Treatment

The frame

There is no antidote. Treatment is: replace what the marrow can't make, push what's left to regenerate faster, keep infection out, and manage the gut and skin. Everything approved is in the second category.

FDA-approved medical countermeasures

All licensed under the Animal Rule — no human efficacy trials exist or can exist. Indication wording is consistently "acute exposure to myelosuppressive doses of radiation." From REMM's countermeasure page:

Drug	Brand	Approved	Dose	Mechanism
Filgrastim	Neupogen	Mar 2015	10 mcg/kg/day SC	G-CSF; neutrophil recovery
Pegfilgrastim	Neulasta	Nov 2015	two 6 mg SC doses, 1 wk apart (≥45 kg)	Pegylated G-CSF
Sargramostim	Leukine	Mar 2018	7–12 mcg/kg/day SC	GM-CSF
Romiplostim	Nplate	28 Jan 2021	10 mcg/kg single SC dose	TPO receptor agonist; platelet recovery
Pegfilgrastim-cbqv	Udenyca	Nov 2022	as Neulasta	biosimilar
Pegfilgrastim-fpgk	Stimufend	Sep 2023	as Neulasta	biosimilar
Pegfilgrastim-bmez	Ziextenzo	Feb 2024	as Neulasta	biosimilar
Filgrastim-txid	Nypozi	Jun 2024	as Neupogen	biosimilar
Filgrastim-sndz	Zarxio	Oct 2024	as Neupogen	biosimilar
Pegfilgrastim-pbbk	Fylnetra	Apr 2025	as Neulasta	biosimilar
Filgrastim-ayow	Releuko	Apr 2025	as Neupogen	biosimilar
Pegfilgrastim-unne	Armlupeg	Nov 2025	as Neulasta	biosimilar

⚠️ Verify the biosimilar approval dates against FDA sources before committing them — they came from a single page fetch and dates are exactly the kind of thing that gets transcribed wrong.

Romiplostim is the mechanistically distinct one and worth its own treatment record. It targets the platelet arm rather than the neutrophil arm — Bussel et al. (PMID:34079225): "Romiplostim binds to and activates the TPO receptor on megakaryocyte precursors, thus promoting cell proliferation and viability, resulting in increased platelet production." The pivotal NHP data (Bunin et al., PMID:37224926) showed a "40% to 55% survival benefit compared with controls, less severe clinical signs, reduced incidence of thrombocytopenia and/or neutropenia." Single dose, which matters enormously for mass-casualty logistics.

Lazarus & Gale's clinical bottom line (PMID:40074513): "The favorable benefit-to-risk ratio of these drugs over hematopoietic cell transplants suggests giving them soon after exposure to acute high-dose and-dose-rate whole body ionizing radiations."

Suggested treatment YAML shape

treatments:
- name: Filgrastim
  therapeutic_modality: OTHER        # 🔎 no ideal value; G-CSF is a recombinant protein
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986                # ✅ VERIFIED
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: filgrastim
      term:
        id: NCIT:C1474               # ✅ VERIFIED in cache/ncit/terms.csv
        label: Filgrastim

⚠️ Two traps here. 1. There's a known pattern in this repo where NCIT drug terms fail therapeutic_agent dynamic-enum validation even when the CURIE and label are both correct — CHEBI is the safer default. But filgrastim/pegfilgrastim/sargramostim/romiplostim are recombinant proteins and peptibodies with no CHEBI terms, so NCIT is the only option. Run just validate-terms on this block specifically and be ready for it to fail. 2. therapeutic_modality has no value that cleanly fits a recombinant cytokine. PROTEIN_REPLACEMENT is wrong (nothing is being replaced), SMALL_MOLECULE is wrong. OTHER is honest. Don't stretch a value to look complete.

Verified NCIT terms for the rest:

Treatment	NCIT	Status
Supportive Care	`NCIT:C15747`	✅
Pharmacotherapy	`NCIT:C15986`	✅
Hematopoietic Cell Transplantation	`NCIT:C15431`	✅
Bone Marrow Transplantation	`NCIT:C15194`	✅
Blood Transfusion	`NCIT:C15192`	✅
Platelet Transfusion	`NCIT:C15366`	✅
Antibiotic Therapy	`NCIT:C15620`	✅
Antifungal Therapy	`NCIT:C15704`	✅
Antiviral Therapy	`NCIT:C16119`	✅
Fluid Therapy	`NCIT:C116537`	✅
Nutritional Support	`NCIT:C15433`	✅
Wound Care Management	`NCIT:C116681`	✅
Skin Transplantation	`NCIT:C15325`	✅
Surgical Procedure	`NCIT:C15329`	✅
Therapeutic Procedure	`NCIT:C49236`	✅
Palliative Therapy	`NCIT:C15292`	✅
Filgrastim / Sargramostim / Romiplostim	`NCIT:C1474` / `NCIT:C1492` / `NCIT:C52183`	✅
Pegfilgrastim	`NCIT:C1854`	✅ (OLS4)

Reminder from the repo's own guidance: NCIT:C15433 Nutritional Support should not be reflexively tagged BEHAVIORAL — here it usually means parenteral nutrition, which isn't a diet-pattern change.

Supportive care backbone

This is where survival actually comes from, and it deserves as much detail as the drugs: - Protective/reverse isolation during neutropenia - Broad-spectrum antimicrobial prophylaxis and treatment — antibacterial, antifungal, antiviral - Transfusion support — and here's the ARS-specific detail that matters: all cellular blood products must be irradiated to prevent transfusion-associated GVHD, because a profoundly lymphopenic irradiated patient cannot reject donor lymphocytes. Leukoreduced and CMV-safe as well. This is a genuine ARS-specific practice point, not generic transfusion medicine - Antiemetics — 5-HT3 antagonists; ondansetron CHEBI:7773 ✅ - Fluid and electrolyte replacement, especially in GI-ARS - Nutritional support, often parenteral when the gut is denuded - Analgesia and wound care for CRS; surgical debridement, grafting, sometimes amputation - Psychosocial support — the Chernobyl and Goiânia experiences both document severe psychological morbidity, including in the unexposed

Hematopoietic cell transplantation

Reserved and controversial. Arnautou & Garnier: HSCT "will be carefully considered on an individual basis, especially for patients who do not respond following 3 weeks of cytokine therapy." The Chernobyl transplant experience was poor — GVHD in the setting of combined injury, plus autologous recovery in patients who'd been transplanted anyway. The modern consensus leans strongly toward cytokines first.

Investigational — the pipeline

Hematopoietic: - TPOm (JNJ-26366821), a PEGylated thrombopoietin mimetic — works through the niche (PMID:38679747): "TPOm interacts with BM vascular and stromal niches to locally support hematopoietic reconstitution." - HemaMax (rHuIL-12) — Phase 1 completed, NCT01742221, "Hematopoietic syndrome due to acute radiation syndrome" - PLX-R18 placental cell therapy — Phase 1, NCT03797040, for post-exposure prophylaxis or treatment of HS-ARS - KMRC011 — Phase 1 completed, NCT03585803, listed condition "Acute radiation syndrome" - 16,16-dimethyl PGE2 — effective as radioprotector but notably not as a mitigator for DEARE (PMID:37014943): given after TBI it "enhances survival from H-ARS but has little impact on RBMD or other DEARE." A nice worked example of directness mattering - Eltrombopag post-TBI — NCT00903929, Phase 1, completed

Radioprotectors (pre-exposure): - BIO 300 (synthetic genistein nanosuspension) — NHP pilot (PMID:39160790): all four treated animals survived to day 60 vs 50% of vehicle controls, but notably "BIO 300 Injectable Suspension did not mediate an improvement in blood cell counts," and the authors conclude "protection against irradiation is attainable without much improvement in the complete blood count (CBC) profile." Oral suspension Phase 1 NCT06741345 completed Dec 2024. ⚠️ n=4 per arm — a pilot, not efficacy - 5-androstenediol / NEUMUNE (PMID:38097137) — IND status granted; "modulate[s] cell cycle progression, reduces radiation-induced apoptosis, and regulates DNA repair" - Gamma-tocotrienol, amifostine (CHEBI:2636 ✅, active metabolite WR-1065 CHEBI:72583 ✅ — but amifostine is approved only for radiotherapy-related xerostomia and cisplatin nephrotoxicity, not ARS)

GI-targeted: - MIIST305, a mucus-layer glycopolymer (PMID:39930324) — the standout result: "Approximately 85% of the animals survived the irradiation exposure... In contrast, no control, Vehicle-treated animals survived past day 10 at this radiation dose." - Anti-ceramide scFv (Nagesh et al., PMID:37815783) — mechanistically the most elegant thing in the pipeline, targeting the Step-3 ceramide arm directly. Mice at 15 Gy + BMT + scFv survived to day 90 with "normal appearance, behavior, and serum biochemistries, and surprisingly, at full autopsy, near-normal physiology in all 42 tissues examined" - Captopril (CHEBI:3380 ✅) — ACE inhibitor, mitigates H-ARS in Göttingen minipigs (PMID:34449797, PMID:38674120); "suppressed radiation-induced IL1B and TNFA" - Microbial metabolites — propionate, tryptophan metabolites, I3A, valeric acid (§6) - Liangxue-Guyuan-Yishen decoction — a TCM formulation with GI-ARS rat data via WNT and MEK/ERK (PMID:37697698)

Cell and EV therapies: - MSCs and MSC-derived extracellular vesicles (Miura & Fujii, PMID:39679884) — promising preclinically, but the authors are appropriately cautious: "the effectiveness of MSC transplantation in addressing acute radiation syndrome affecting organs in irradiated individuals is limited" and "further investigation is required" - Umbilical cord blood (Hurley et al., PMID:37967239) — improved survival, hematopoietic recovery, reduced GI damage, and mitigation of pneumonitis/fibrosis in preclinical work - Romiplostim-induced EVs (Yamaguchi et al., PMID:37238707) — a genuinely odd and interesting result: serum EVs from romiplostim-rescued mice, transferred to other irradiated mice, "drastically improved by 50-100%" their 30-day survival, with miR-144-5p found only in EVs from treated animals

Combined injury: nothing. Worth stating as an explicit gap (PMID:36947602).

Treatment algorithms

Follow the METREPOL response category. Broadly: decontaminate → assess dose (clinical + biodosimetry) → cytokines within 24 h if dose >2 Gy → supportive care scaled to RC → HSCT decision at ~3 weeks for non-responders → DEARE surveillance for survivors.

Pharmacogenomics: none established for ARS. NOT_APPLICABLE.

Personalized medicine: dose-guided rather than genotype-guided. The "biomarker" here is absorbed dose, and the whole biodosimetry enterprise exists to make treatment personalized in that sense.

13. Prevention

Primary prevention — where nearly all the real benefit lives

Radiation protection fundamentals: time, distance, shielding. ALARA.
Source security and regulatory control — the Goiânia accident happened because a teletherapy source was abandoned in an unsecured building. "A caesium-137 teletherapy unit was left unsecured after an institute moved to new premises, becoming totally insecure." Every orphan-source accident is a regulatory failure before it's a medical one.
Reactor safety, criticality controls, transport regulation (IAEA framework)
Emergency planning — sheltering, evacuation, exclusion zones
Occupational dosimetry and dose limits
Nuclear nonproliferation and counterterrorism — the actual primary prevention for the scenarios driving current funding

Pharmacological primary prevention: none approved. Restating Singh et al. (PMID:39160790): "Currently, there is no radiation medical countermeasure approved by the U.S. FDA which can be used before radiation exposure to protect exposed individuals."

The KI distinction, one more time

Potassium iodide (CHEBI:8346 ✅) is thyroid-blocking prophylaxis against radioiodine uptake. It is on every emergency-planning list and is not ARS prophylaxis. If the KB entry lists it under treatments: without a scoping note, a reader will reasonably conclude it protects against whole-body exposure. It does not. Same logic for Prussian blue (Cs/Tl decorporation) and Ca-DTPA/Zn-DTPA (transuranic decorporation) — these are for internal contamination, which is a different disease process with a different time course. Consider ECTO:9000084 "exposure to iodine" ✅ if you model the radioiodine arm at all, and consider whether internal contamination deserves a differentials: entry rather than a treatment entry.

Secondary prevention

Mass-casualty triage biodosimetry (§10) — rapid identification of who actually got a dose so countermeasures go to the right people and the worried-well don't consume the supply.

Tertiary prevention

Countermeasure administration within the therapeutic window; infection prophylaxis; irradiated blood products; DEARE surveillance — renal function, pulmonary function, ophthalmologic exam, cardiovascular risk management, cancer screening. The Ukrainian ARS survivor cohort is the model for this.

Immunization

Not applicable — no vaccine, no infectious etiology. (Standard vaccination status matters for a neutropenic patient's infection risk, but that's not ARS prevention.)

Genetic screening and counseling

Not applicable. No carrier screening, no PGD, no prenatal testing. NCIT:C15240 Genetic Counseling ✅ has a vanishingly narrow role — only if a DNA-repair syndrome is uncovered incidentally through disproportionate radiosensitivity.

Public health

Emergency preparedness training (the simulation curricula like PMID:37538304 exist because clinicians genuinely don't recognize this), stockpiling (Strategic National Stockpile holds the approved cytokines), risk communication, environmental monitoring and remediation, food/water controls after a release.

14. Other Species / Natural Disease

Taxonomy

Every mammal gets ARS, with the same subsyndrome structure and different dose thresholds. Verified taxon IDs from cache/ncbitaxon/terms.csv:

NCBITaxon:9606 Homo sapiens ✅ · NCBITaxon:10090 Mus musculus ✅ · NCBITaxon:10116 Rattus norvegicus ✅ · NCBITaxon:9544 Macaca mulatta ✅ · NCBITaxon:9615 Canis lupus familiaris ✅ · NCBITaxon:9823 Sus scrofa ✅ · NCBITaxon:9825 Sus scrofa domesticus ✅ · NCBITaxon:7955 Danio rerio ✅

🔎 LEAD: Macaca fascicularis (cynomolgus).

Comparative radiosensitivity

Species differ substantially in LD50 — dogs are notably more radiosensitive than mice, primates intermediate. ⚠️ I did not find a single citable modern comparative table, and the numbers floating around secondary sources vary with dose rate, strain, and supportive care. Don't tabulate species LD50s without a primary citation per row. One 2025 paper directly compares macaque species ("Comparison of sensitivity of rhesus and cynomolgus macaque for acute radiation effects", Sci Rep) — worth chasing for a proper citation.

Natural disease in other species

Yes, and it's documented. Cannon & Kiang (PMID:32663058) reviewed wildlife after Chernobyl and Fukushima: "Humans were evacuated from the immediate regions but the wildlife stayed and continued to be affected." Their review covers effects on "vegetation, insects, fish, birds and mammals," and notes that "adaptation to radiation is evident and the ecosystems have dynamically changed."

Domestic animals in the Chernobyl exclusion zone experienced ARS. There is no established naturally occurring animal ARS outside of accidental exposure — no OMIA entry, because it isn't a genetic condition.

VBO breed identifiers: not applicable — no breed predisposition.

Orthologous genes: the DDR is deeply conserved (ATM, TP53, the MRN complex, NHEJ machinery all have orthologs from yeast through mammals), which is exactly why model organisms work here. 🔎 Specific NCBI Gene IDs not retrieved.

Zoonosis / transmission

Not applicable. ARS is not transmissible. Worth stating explicitly, because there is a persistent public misconception that irradiated people are themselves radioactive. They are not — unless they carry internal or external contamination, which is a separate and real concern for responders. That distinction (irradiation ≠ contamination) is worth a notes: line; it's the single most consequential public-understanding error about this disease.

15. Model Organisms

Because of the Animal Rule, model organisms aren't a supporting line of evidence here — they are the regulatory basis for every approved therapy. That inverts the usual weighting and should be said in the entry.

The consortium context

MCART (Medical Countermeasures Against Radiological Threats), NIAID-sponsored, is the organizing body: "charged with developing medical countermeasures (MCM) to treat the key sequelae of acute radiation syndrome (ARS) and the delayed effects of acute radiation exposure (DEARE)." Its models are built "within the criteria of the FDA's 'animal rule.'" Key reference: MacVittie & Farese, PMID:32868706, "Defining the Concomitant Multiple Organ Injury within the ARS and DEARE in an Animal Model Research Platform."

Models

Mouse — NCBITaxon:10090 ✅ - C57BL/6J TBI — the workhorse H-ARS model, 30-day survival endpoint, LD50/30 typically ~7–8 Gy strain- and facility-dependent - Partial-body irradiation with 5% bone marrow shielding at 13 Gy — the standard GI-ARS model (PMID:39930324). The shielding is the whole trick: without it the animal dies of H-ARS before GI-ARS can be studied - 15 Gy WBI — the ~90% GI-ARS lethal dose for C57BL/6J (PMID:37815783) - ASMase-knockout (Smpd1−/−) — the genetic proof of the ceramide arm - DEARE longitudinal model — mice followed to 12+ months (PMID:37014943) - Recapitulation: excellent for H-ARS kinetics and mechanism. Limitations: small body mass changes dosimetry; different marrow reserve; supportive care not comparable to human ICU; 30-day endpoint misses DEARE by design

Rat — NCBITaxon:10116 ✅ - WAG/RijCmcr — Gasperetti et al. (PMID:36688956) established it "as an effective model for the evaluation of medical countermeasures (MCM) for acute hematologic radiation syndrome (H-ARS)." LD50/30 determined for adult and pediatric animals, both sexes. "87.5% and 100% of adult rats succumb to lethal hematopoietic acute radiation syndrome (H-ARS) at TBI doses of 8 and 8.5 Gy, respectively", and pegfilgrastim "improved 30 d survival from 12.5% to 83% at 8 Gy and from 0% to 63% at 8.5 Gy." - The best DEARE model — followed to 300 days with renal endpoints. Lung-DEARE at PBI >12 Gy (pneumonitis days 50–100); kidney-DEARE at >8 Gy (BUN >120 mg/dL)

Non-human primate — NCBITaxon:9544 ✅ (rhesus); cynomolgus 🔎 - The pivotal licensure model. Farese et al. (PMID:22929469): 48 rhesus macaques, blinded and randomized, LD30/60 7.06 Gy, LD50/60 7.52 Gy, LD70/60 7.99 Gy, with supportive care, "with a relatively steep slope of 1.13 probits per linear dose" - Different radiation sources give different curves — a LINAC 6MV photon study reported LD30/50/70 of 5.71 / 6.78 / 7.84 Gy. Source and dose rate are not interchangeable - Recapitulation: the closest to human physiology and supportive care. Limitations: cost, ethics, small n (the BIO 300 study had four animals per arm), and macaques with full care substantially out-tolerate unsupported humans

Minipig — NCBITaxon:9823 / NCBITaxon:9825 ✅ - Göttingen minipig H-ARS — captopril studies at 1.79–1.80 Gy Co-60 (PMID:34449797, PMID:38674120); skin physiology is the closest available to human, making it the preferred CRS model - Sinclair minipig GI-ARS — dose-finding with microbiome and inflammasome endpoints (PMID:39012765) - ⚠️ Provenance caution: the two Kenchegowda/Seed/Singh minipig methodology papers (PMID:34402700, PMID:32892657) came back with one flagged RETRACTED. Check retraction status before citing either

Canine — NCBITaxon:9615 ✅ — historical importance (much of the classical dose-response and marrow-transplant work), less used now.

Zebrafish — NCBITaxon:7955 ✅ — 🔎 not prominent in the ARS literature I sampled; more common for developmental radiobiology.

In vitro / NAM systems: - Human intestinal organoids — used to validate the macrophage/NRG1 regeneration finding (PMID:40086603) and the human tuft-cell reserve pool (PMID:39358509). These belong in experimental_models: (not animal_models:) - Human intestinal resection tissue — the strongest evidence tier available for GI mechanism - Hematopoietically humanized mice — used for candidate protein biodosimetry markers - Primary human lymphocyte culture — the substrate for the dicentric assay itself

Modeling these in dismech

Use ModelMechanismLink on animal_models: entries (this is what modeled_mechanisms is for — animal models never belong in experimental_models:). Sketch:

animal_models:
- name: Rhesus macaque total-body irradiation with medical management
  species: Rhesus macaque
  publication: PMID:22929469
  modeled_mechanisms:
  - target: <the H-ARS marrow failure node>
    relationship: RECAPITULATES
    fidelity: HIGH
    description: >-
      Dose-response for hematopoietic lethality with supportive care;
      the licensure model for every FDA-approved H-ARS countermeasure.
    limitations: >-
      LD50/60 of 7.52 Gy with full supportive care substantially exceeds the
      human LD50/60 of roughly 2.7-3.1 Gy estimated from atomic-bomb survivor
      marrow doses, so the dose axis does not transfer directly to humans.
    readouts:
    - name: 60-day survival
      target: <same node>
      direction: DECREASED

And there's at least one good FAILS_TO_RECAPITULATE / HUMAN_MODEL_MISMATCH candidate here: the behavioral and cognitive DEARE findings in mice (PMID:37014943 — anxiety changes in females, blunted shock flinch, altered exploratory behavior in males) have no established human counterpart. That's exactly the "evidence exists in a model, translational validity is the open question" shape the schema's HUMAN_MODEL_MISMATCH was built for.

Model resources

MGI, RGD, ZFIN, Alliance of Genome Resources for the standard organism databases; MCART for consortium models; NIAID/RNCP for the countermeasure program.

Gaps and honest non-findings

Things I looked for and did not find, so nobody re-runs the same search:

A validated QoL instrument for ARS. None found. EQ-5D/SF-36/PROMIS data: absent.
An ARS-specific epigenetic mechanism with enough weight to be a pathophysiology node.
Spatial transcriptomics or CRISPR screens specific to ARS.
A clean modern comparative species LD50 table with a citable primary source.
A definitive ICD-11 code. One source said NF00, the template guessed NF06. Unresolved.
A DOID identifier.
Human efficacy data for any ARS drug. By construction — the Animal Rule exists because this data cannot exist.
Recent ClinicalTrials.gov ARS-condition trials are sparse: NCT01742221 (HemaMax), NCT03585803 (KMRC011), NCT03797040 (PLX-R18), NCT00903929 (eltrombopag), NCT06741345 (BIO 300 oral, Phase 1). Most acute radiation syndrome query hits are TBI-conditioning transplant trials, which are a different thing wearing similar words — classic Named Entity Confusion, and worth a note in the entry so the next curator doesn't fall in.
LOINC codes for the ARS lab panel — not resolved.

Suggested curation approach, briefly

Some structural calls that follow from the above:

entry_type: DISEASE. ARS is a real clinical entity with a defined mechanism, not a grouping — even though it bundles four subsyndromes.
Model the four subsyndromes as has_subtypes, not separate entries. They share one etiology, one dose axis, and one temporal architecture; they differ only in which tissue's threshold you crossed. Names should be short and slug-friendly: H-ARS, GI-ARS, CRS, CNS-ARS. Then use the subtype: foreign key on phenotypes and progression records.
The initiating node is the exposure, wired via environmental[].influences_mechanisms with TRIGGERS. If it isn't wired, the pathograph will have every mechanism node orphaned from its cause — one of the recurring reviewer findings in this repo.
Watch for module conformance opportunities. just list-modules before you build anything — cellular senescence, inflammaging, and any fibrosis or DAMP/inflammation module are plausible conformance targets, and there may be a toxicology-family module that already covers part of this chain under a name you wouldn't guess.
Give the "irradiation ≠ contamination" distinction and the "KI is not ARS prophylaxis" distinction each a notes: line. They're the two errors most likely to be introduced by a future well-meaning editor.
Expect heavy MODEL_ORGANISM grading and don't apologize for it — but keep the human accident evidence (Chernobyl, Goiânia, Tokai-mura, A-bomb) carrying the human phenotype claims.

Sources

Primary literature (PMIDs cited above): 40368913 · 39025400 · 38616048 · 39930324 · 39000080 · 40074513 · 37280005 · 38679747 · 39679884 · 37967239 · 39160790 · 37238707 · 36688956 · 38097137 · 37014943 · 38674120 · 37815783 · 37697698 · 37538304 · 37224926 · 20445398 · 38333215 · 36947602 · 34488201 · 34801995 · 34233299 · 33979447 · 32663058 · 37018160 · 36543843 · 38687685 · 35994701 · 38854157 · 38029728 · 37742625 · 33122357 · 38706205 · 31931652 · 40192235 · 36253079 · 36368026 · 34084131 · 31019301 · 39358509 · 38848678 · 40086603 · 37669929 · 22929469 · 32868706 · 34449797 · 39012765 · 32355263 · 32791865 · 36752571 · 30421807 · 34079225 · 1762100 · 2693695 · 17993851 · 18544701 · 39270512 · 37642199 · 39600027 · 37149389 · 38003561 · 34402700 · 39355046

Databases and guidance: - MONDO:0033938 via EBI OLS4 - Orphanet — Acute radiation syndrome (ORPHA:454831) - MeSH D054508 - ICD-10-CM T66 - REMM — Acute Radiation Syndrome · Myeloid Cytokines for H-ARS · Time Phases of ARS · Lymphocyte Depletion Kinetics · Time to Onset of Vomiting - CDC — Acute Radiation Syndrome: Information for Clinicians - AFRRI — Medical Management of Radiological Casualties, 4th ed. - IAEA — The Radiological Accident in Goiânia · IAEA — Tokaimura · UNSCEAR — Chernobyl - REAC/TS Radiation Accident Registry overview - NIAID — approval of romiplostim for acute radiation injury · FDA Nplate approval letter, 2021 - MCART Consortium Animal Models Series - ClinicalTrials.gov: NCT01742221 · NCT03585803 · NCT03797040 · NCT00903929 · NCT06741345

One last time, because it's the thing most likely to bite: every quote in here needs re-verification against just fetch-reference before it becomes a snippet:, and every 🔎 CURIE needs just validate-terms before it becomes a term:. The verified ✅ ones came from this repo's own caches or live OLS, so those should sail through — but the MONDO and ECTO terms in particular are worth a validation run in both the worktree and the primary checkout, since the write hook validates from the primary and that's exactly where a cache gap hides.

Reference Validation

Checked with linkml-reference-validator 0.2.1.

Outcome	Count
References checked	68
Resolved	68
Unresolved (possible confabulation)	0
Unverifiable	0
Quoted claims checked	2
Quoted claims found in source	2
Quoted claims not found in source	0
References weighed for topical relevance	68
On topic	44
Off topic	0

All extracted references resolved successfully.

Ask OpenScientist

OpenScientist Report

Classifications

Subtypes

Discussions and Knowledge Gaps

Pathophysiology

Pathograph

Phenotypes

Medical Actions

Environmental Factors

Diagnosis

Stages

Clinical Trials

Experimental Models

Animal Models

Source YAML

References & Deep Research

References

Deep Research

Acute Radiation Syndrome — Disease Characteristics Research Report

⚠️ Read this before you paste anything into a snippet: field

1. Disease Information

What it is

Identifiers

Where the knowledge comes from — and why this matters for evidence grading

2. Etiology

Primary cause

Exposure scenarios (the real-world routes)

Dose–effect thresholds (the load-bearing numbers)

Modifying factors — physical

Modifying factors — host

Genetic risk factors

Protective factors

Gene–environment interaction

3. Phenotypes

The four-phase temporal architecture

Prodromal phenotypes

Hematopoietic subsyndrome (H-ARS) — ≥ ~2 Gy

Gastrointestinal subsyndrome (GI-ARS) — ≥ ~6 Gy

Cutaneous radiation syndrome (CRS)

Neurovascular / cardiovascular / CNS subsyndrome — very high dose

Delayed effects (DEARE) — survivors

4. Genetic / Molecular Information

Causal genes: none

Somatic / acquired genomic change — the actual "genetics" of ARS

Genes as biodosimetry readout (not as cause)

Mechanism-relevant genes (for pathophysiology node binding)

Epigenetics

Chromosomal abnormalities

5. Environmental Information

6. Mechanism / Pathophysiology

The causal chain, step by step

Branch A — Hematopoietic ARS (≥ ~2 Gy)

Branch B — Gastrointestinal ARS (≥ ~6 Gy)

Branch C — Cutaneous radiation syndrome

Branch D — Neurovascular / CNS syndrome (very high dose)

The microbiome layer — a real modifier, not decoration

Cell death modes beyond apoptosis

Suggested GO / CL bindings for pathophysiology nodes

Molecular profiling

7. Anatomical Structures Affected

Organ level

Tissue and cell level

Subcellular level

Localization / lateralization

8. Temporal Development

Onset

Progression and the phase structure

Critical intervention windows — the actionable part

Remission

9. Inheritance and Population

Inheritance

Epidemiology

Demographics

10. Diagnostics

Clinical dose assessment — the frontline

Biodosimetry — the confirmatory layer

Routine clinical workup

Genetic testing

Differential diagnosis

⚠️ Read this before you paste anything into a `snippet:` field