Deficiency of Adenosine Deaminase 2

Mendelian MONDO:0014306 Pathograph 22 Show in embeddings browser Vasculitis Type 1 interferonopathy of childhood Hereditary disorder of connective tissue

Deficiency of adenosine deaminase 2 (DADA2) is a rare autosomal recessive systemic autoinflammatory vasculopathy caused by biallelic loss-of-function variants in ADA2 (formerly CECR1), encoding the major extracellular adenosine deaminase, which also acts as a secreted growth factor. Reduced ADA2 enzymatic activity and impaired growth-factor function disrupt endothelial integrity and myeloid homeostasis, driving a spectrum of intermittent fevers, livedo racemosa, early-onset lacunar and hemorrhagic strokes, polyarteritis-nodosa-like vasculitis, immunodeficiency, and bone marrow / hematologic abnormalities. Disease typically presents in childhood with marked inter- and intrafamilial variability. Anti-TNF agents are the mainstay of treatment and prevent stroke; hematopoietic stem cell transplantation can correct severe hematologic and immune disease.

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6
Pathophys.
16
Phenotypes
22
Pathograph
1
Genes
2
Medical Actions
1
References
1
Deep Research
⚙

Pathophysiology

6
ADA2 Loss of Function
Biallelic loss-of-function variants in ADA2 (formerly CECR1) markedly reduce or abolish the extracellular adenosine deaminase 2 enzyme, the major plasma adenosine deaminase. Diagnosis is supported by low (<5% of normal) or undetectable ADA2 catalytic activity in plasma or serum. ADA2 is a secreted protein with both adenosine-deaminating activity and growth-factor activity, so loss of function impairs purine catabolism and ADA2-dependent signaling in the vasculature and myeloid compartment.
adenosine catabolic process GO:0006154 ↓ DECREASED
Downstream
Endothelial Damage and Vasculopathy
Myeloid Inflammatory Dysregulation
Lysosomal DNA Editing and TLR9 Immune Sensing
Show evidence (2 references)
PMID:24552284 SUPPORT Human Clinical
"Patients had a marked reduction in the levels of ADA2 and ADA2-specific enzyme activity in the blood."
Demonstrates that recessive CECR1/ADA2 mutations cause loss of ADA2 protein and enzyme activity in patients, the primary biochemical lesion.
PMID:24552285 SUPPORT Human Clinical
"Recessive loss-of-function mutations of ADA2, a growth factor that is the major extracellular adenosine deaminase, can cause polyarteritis nodosa vasculopathy with highly varied clinical expression."
Establishes ADA2 as the major extracellular adenosine deaminase and a growth factor whose loss of function causes the vasculopathy.
Endothelial Damage and Vasculopathy
Loss of ADA2 compromises endothelial integrity. Biopsies of skin, liver, and brain show vasculopathic changes with compromised endothelial integrity, endothelial cellular activation, and inflammation. Patient monocytes induce damage in cocultured endothelial-cell layers, linking myeloid dysregulation to the vascular injury that underlies stroke and polyarteritis-nodosa-like vasculitis.
vascular endothelial cell CL:0002139
inflammatory response GO:0006954 ↑ INCREASED
Downstream
Vascular and Neurologic Manifestations
Show evidence (2 references)
PMID:24552284 SUPPORT Human Clinical
"Skin, liver, and brain biopsies revealed vasculopathic changes characterized by compromised endothelial integrity, endothelial cellular activation, and inflammation."
Direct histopathologic evidence of endothelial injury and vascular inflammation in DADA2 patient tissues.
PMID:24552284 SUPPORT In Vitro
"Monocytes from patients induced damage in cocultured endothelial-cell layers."
In vitro coculture shows DADA2 patient monocytes directly damage endothelium, mechanistically linking myeloid cells to vasculopathy.
Myeloid Inflammatory Dysregulation
ADA2 deficiency skews monocyte/macrophage differentiation toward a proinflammatory state and disrupts neutrophil homeostasis. In a zebrafish model, knockdown of the ADA2 homologue caused intracranial hemorrhages and neutropenia, phenotypes rescued by wild-type but not mutant human CECR1, implicating ADA2 in myeloid and vascular development. Proinflammatory cytokines, including TNF, drive the autoinflammatory phenotype, which is why TNF inhibition is clinically effective.
monocyte CL:0000576 macrophage CL:0000235 neutrophil CL:0000775
macrophage activation GO:0042116 ↑ INCREASED tumor necrosis factor production GO:0032640 ↑ INCREASED
Downstream
Hematologic Manifestations
Show evidence (1 reference)
PMID:24552284 SUPPORT Model Organism
"Knockdown of a zebrafish ADA2 homologue caused intracranial hemorrhages and neutropenia - phenotypes that were prevented by coinjection with nonmutated (but not with mutated) human CECR1."
Model-organism data linking ADA2 loss to hemorrhage and neutropenia and confirming the variants are loss-of-function.
Vascular and Neurologic Manifestations
Endothelial injury and systemic vasculopathy produce intermittent fevers, livedoid rash, early-onset lacunar (ischemic) and hemorrhagic strokes, hepatosplenomegaly, hypertension, and cutaneous or systemic polyarteritis nodosa.
Downstream
Recurrent fever
Livedo racemosa
Stroke
Ischemic stroke
Intracranial hemorrhage
Polyarteritis nodosa
Hepatosplenomegaly
Hypertension
Arthritis
Show evidence (1 reference)
PMID:24552284 SUPPORT Human Clinical
"We observed a syndrome of intermittent fevers, early-onset lacunar strokes and other neurovascular manifestations, livedoid rash, hepatosplenomegaly, and systemic vasculopathy in three unrelated patients."
Describes the core inflammatory/vascular clinical syndrome of DADA2.
Hematologic Manifestations
Bone marrow failure and cytopenias are a major DADA2 phenotype group, including pure red cell aplasia, immune-mediated neutropenia, and pancytopenia. These hematologic features respond variably to anti-TNF therapy and may require hematopoietic stem cell transplantation.
Downstream
Immunodeficiency
Decreased circulating immunoglobulin concentration
Pure red cell aplasia
Decreased total neutrophil count
Pancytopenia
Thrombocytopenia
Decreased total lymphocyte count
Show evidence (1 reference)
PMID:35095905 SUPPORT Human Clinical
"Hematologic findings including pure red cell aplasia (PRCA), immune-mediated neutropenia, and pancytopenia were observed in half of patients."
Cohort evidence that hematologic manifestations are a prominent, frequent DADA2 phenotype.
Lysosomal DNA Editing and TLR9 Immune Sensing
An emerging (2024) mechanistic model expands the classical extracellular adenosine paradigm. ADA2 localizes within lysosomes, where it acts as a deoxyadenosine deaminase on DNA, converting deoxyadenosine (dA) to deoxyinosine (dI). This dA-to-dI editing modulates lysosomal innate immune sensing of nucleic acids through Toll-like receptor 9 (TLR9), providing a cell-intrinsic mechanism that may drive the type I interferon and TNF pathway activation seen in DADA2 (a recognized type 1 interferonopathy of childhood).
toll-like receptor 9 signaling pathway GO:0034162 ⚠ ABNORMAL type I interferon production GO:0032606 ↑ INCREASED
Downstream
Myeloid Inflammatory Dysregulation
Show evidence (1 reference)
PMID:39441717 SUPPORT In Vitro
"we demonstrate that dA-to-dI editing of DNA molecules and ADA2 regulate lysosomal immune sensing of nucleic acids (NAs) by modulating Toll-like receptor 9 (TLR9) activation."
Establishes the emerging lysosomal DNA-editing / TLR9 mechanism that may underlie the innate-immune activation of DADA2, complementing the extracellular-adenosine model.
⬡

Pathograph

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Pathograph: causal mechanism network for Deficiency of Adenosine Deaminase 2 Interactive directed graph showing how pathophysiology mechanisms, phenotypes, genetic factors and variants, experimental models, environmental triggers, and treatments relate through causal and linked edges.
●

Phenotypes

16
Blood 6
Decreased circulating immunoglobulin concentration Decreased circulating immunoglobulin concentration HP:0004313
Show evidence (1 reference)
PMID:35095905 SUPPORT Human Clinical
"Evidence of immune dysregulation was commonly observed, including hypogammaglobulinemia, absent to low class-switched memory B cells, and inadequate response to vaccination."
Documents hypogammaglobulinemia in the DADA2 cohort.
Pure red cell aplasia Pure red cell aplasia HP:0012410
Show evidence (1 reference)
PMID:35095905 SUPPORT Human Clinical
"Hematologic findings including pure red cell aplasia (PRCA), immune-mediated neutropenia, and pancytopenia were observed in half of patients."
Pure red cell aplasia documented as a DADA2 hematologic phenotype.
Decreased total neutrophil count Decreased total neutrophil count HP:0001875
Show evidence (1 reference)
PMID:35095905 SUPPORT Human Clinical
"Hematologic findings including pure red cell aplasia (PRCA), immune-mediated neutropenia, and pancytopenia were observed in half of patients."
Documents immune-mediated neutropenia in DADA2.
Pancytopenia Pancytopenia HP:0001876
Show evidence (1 reference)
PMID:35095905 SUPPORT Human Clinical
"Hematologic findings including pure red cell aplasia (PRCA), immune-mediated neutropenia, and pancytopenia were observed in half of patients."
Pancytopenia documented as a DADA2 hematologic phenotype.
Thrombocytopenia Thrombocytopenia HP:0001873
Show evidence (1 reference)
PMID:31393689 SUPPORT Human Clinical
"lymphopenia, neutropenia, pure red cell aplasia, thrombocytopenia, or pancytopenia"
GeneReviews lists thrombocytopenia among the hematologic disorders of DADA2.
Decreased total lymphocyte count Decreased total lymphocyte count HP:0001888
Show evidence (1 reference)
PMID:31393689 SUPPORT Human Clinical
"lymphopenia, neutropenia, pure red cell aplasia, thrombocytopenia, or pancytopenia"
GeneReviews lists lymphopenia among the hematologic disorders of DADA2.
Cardiovascular 5
Stroke FREQUENT Stroke HP:0001297
Show evidence (1 reference)
PMID:24552284 SUPPORT Human Clinical
"Loss-of-function mutations in CECR1 were associated with a spectrum of vascular and inflammatory phenotypes, ranging from early-onset recurrent stroke to systemic vasculopathy or vasculitis."
Establishes early-onset recurrent stroke as a core DADA2 phenotype.
Ischemic stroke Ischemic stroke HP:0002140
Show evidence (1 reference)
PMID:24552284 SUPPORT Human Clinical
"We observed a syndrome of intermittent fevers, early-onset lacunar strokes and other neurovascular manifestations, livedoid rash, hepatosplenomegaly, and systemic vasculopathy in three unrelated patients."
Documents early-onset lacunar (ischemic) strokes in DADA2.
Polyarteritis nodosa Medium vessel vasculitis HP:6000658
Show evidence (1 reference)
PMID:24552285 SUPPORT Human Clinical
"In all the families, vasculitis was caused by recessive mutations in CECR1, the gene encoding adenosine deaminase 2 (ADA2)."
DADA2 was independently identified as the cause of familial polyarteritis nodosa vasculitis. The ontology term Medium vessel vasculitis (HP:6000658) precisely captures the PAN-type vasculitis, whose ontology definition explicitly cites polyarteritis nodosa.
Hepatosplenomegaly Hepatosplenomegaly HP:0001433
Show evidence (1 reference)
PMID:24552284 SUPPORT Human Clinical
"We observed a syndrome of intermittent fevers, early-onset lacunar strokes and other neurovascular manifestations, livedoid rash, hepatosplenomegaly, and systemic vasculopathy in three unrelated patients."
Hepatosplenomegaly was present in the founding DADA2 cohort.
Hypertension Hypertension HP:0000822
Show evidence (1 reference)
PMID:31393689 SUPPORT Human Clinical
"Hypertension and hepatosplenomegaly are often found."
GeneReviews notes hypertension is often found in DADA2.
Immune 1
Immunodeficiency Immunodeficiency HP:0002721
Show evidence (1 reference)
PMID:35095905 SUPPORT Human Clinical
"Evidence of immune dysregulation was commonly observed, including hypogammaglobulinemia, absent to low class-switched memory B cells, and inadequate response to vaccination."
Cohort evidence of the immunodeficiency/immune-dysregulation phenotype.
Metabolism 1
Recurrent fever Recurrent fever HP:0001954
Show evidence (1 reference)
PMID:24552284 SUPPORT Human Clinical
"We observed a syndrome of intermittent fevers, early-onset lacunar strokes and other neurovascular manifestations, livedoid rash, hepatosplenomegaly, and systemic vasculopathy in three unrelated patients."
Intermittent fevers were a defining feature of the initial DADA2 cohort.
Musculoskeletal 1
Arthritis Arthritis HP:0001369
Show evidence (1 reference)
PMID:31393689 SUPPORT Human Clinical
"musculoskeletal involvement (myalgia/arthralgia, arthritis, myositis)"
GeneReviews documents musculoskeletal involvement including arthritis in DADA2.
Other 2
Livedo racemosa Livedo racemosa HP:0033260
Show evidence (1 reference)
PMID:35095905 SUPPORT Human Clinical
"first described in patients with fevers, recurrent strokes, livedo racemosa, and polyarteritis nodosa in 2014"
Livedo racemosa is a cardinal cutaneous feature of DADA2.
Intracranial hemorrhage Intracranial hemorrhage HP:0002170
Show evidence (2 references)
PMID:24552284 SUPPORT Model Organism
"Knockdown of a zebrafish ADA2 homologue caused intracranial hemorrhages and neutropenia - phenotypes that were prevented by coinjection with nonmutated (but not with mutated) human CECR1."
Zebrafish model recapitulates the intracranial hemorrhage phenotype seen in DADA2 patients (hemorrhagic strokes are part of the human phenotype per the GeneReviews chapter).
PMID:31393689 SUPPORT Human Clinical
"manifest as early-onset ischemic (lacunar) and/or hemorrhagic strokes, or as"
GeneReviews documents hemorrhagic strokes / intracranial hemorrhage as part of the human DADA2 vasculitis phenotype, providing human clinical support alongside the zebrafish model.
🧬

Genetic Associations

1
ADA2 biallelic loss of function (Pathogenic Variants)
Gene: ADA2 hgnc:1839
Autosomal recessive
Show evidence (2 references)
PMID:24552285 SUPPORT Human Clinical
"In all the families, vasculitis was caused by recessive mutations in CECR1, the gene encoding adenosine deaminase 2 (ADA2)."
Establishes recessive (biallelic) CECR1/ADA2 loss-of-function variants as the cause of DADA2. CECR1 is the former symbol for ADA2.
PMID:24552284 SUPPORT Human Clinical
"All nine patients carried recessively inherited mutations in CECR1 (cat eye syndrome chromosome region, candidate 1), encoding adenosine deaminase 2 (ADA2), that were predicted to be deleterious; these mutations were rare or absent in healthy controls."
Independent confirmation of recessive deleterious CECR1/ADA2 variants in patients.
💊

Medical Actions

2
Anti-TNF Therapy
Action: anti-TNF therapy Ontology label: Pharmacotherapy NCIT:C15986
Agent: adalimumab NCIT:C65216 etanercept NCIT:C2381
Anti-tumor necrosis factor (TNF) agents (etanercept, adalimumab, golimumab, infliximab, certolizumab) are the drugs of choice for symptomatic and asymptomatic individuals with biallelic ADA2 pathogenic variants. They prevent and eliminate autoinflammatory/vasculitic manifestations and reduce the risk of ischemic stroke. Hematologic and immune features respond more variably, and anti-TNF agents have little effect on severe bone marrow failure.
Show evidence (2 references)
PMID:35095905 SUPPORT Human Clinical
"We significantly extended our experience using anti-TNF agents, with no strokes observed in 2026 patient months on TNF inhibitors."
Cohort evidence that anti-TNF therapy prevents stroke in DADA2, the mainstay of treatment.
PMID:33420503 SUPPORT Human Clinical
"Anti-TNF treatment significantly reduced the incidence of ischaemic events and other vasculitic manifestations of DADA2, but was not effective for immunodeficiency or bone marrow failure."
Multicenter retrospective study quantifying that anti-TNF therapy prevents ischemic events and vasculitis but not the hematologic/immune phenotype, consistent with anti-TNF as first-line disease-modifying therapy.
Hematopoietic Stem Cell Transplantation
Action: hematopoietic stem cell transplantation MAXO:0000747
Allogeneic hematopoietic cell transplantation (HCT) can correct severe hematologic and immunologic DADA2 disease that is refractory to anti-TNF therapy; transplanted patients in the NIH cohort discontinued anti-TNF therapy after engraftment.
Show evidence (2 references)
PMID:35095905 SUPPORT Human Clinical
"All transplanted patients are still alive and have discontinued anti-TNF therapy."
Cohort evidence that allogeneic HCT can be curative for DADA2 hematologic / immune disease, allowing discontinuation of anti-TNF therapy.
PMID:34324127 SUPPORT Human Clinical
"HCT was an effective treatment for DADA2, successfully reversing the refractory cytopenia, as well as the vasculopathy and immunodeficiency."
International 30-patient series showing HCT reverses refractory cytopenia, vasculopathy, and immunodeficiency, establishing HCT as a definitive cure for DADA2.
{ }

Source YAML

click to show 
name: Deficiency of Adenosine Deaminase 2
creation_date: "2026-06-03T00:00:00Z"
category: Mendelian
disease_term:
  preferred_term: Deficiency of adenosine deaminase 2
  term:
    id: MONDO:0014306
    label: deficiency of adenosine deaminase 2
description: >
  Deficiency of adenosine deaminase 2 (DADA2) is a rare autosomal recessive
  systemic autoinflammatory vasculopathy caused by biallelic loss-of-function
  variants in ADA2 (formerly CECR1), encoding the major extracellular adenosine
  deaminase, which also acts as a secreted growth factor. Reduced ADA2 enzymatic
  activity and impaired growth-factor function disrupt endothelial integrity and
  myeloid homeostasis, driving a spectrum of intermittent fevers, livedo
  racemosa, early-onset lacunar and hemorrhagic strokes, polyarteritis-nodosa-like
  vasculitis, immunodeficiency, and bone marrow / hematologic abnormalities.
  Disease typically presents in childhood with marked inter- and intrafamilial
  variability. Anti-TNF agents are the mainstay of treatment and prevent stroke;
  hematopoietic stem cell transplantation can correct severe hematologic and
  immune disease.
parents:
- Vasculitis
- Type 1 interferonopathy of childhood
- Hereditary disorder of connective tissue
references:
- reference: PMID:31393689
  title: "Adenosine Deaminase 2 Deficiency."
  tags:
  - GeneReviews
pathophysiology:
- name: ADA2 Loss of Function
  description: >
    Biallelic loss-of-function variants in ADA2 (formerly CECR1) markedly
    reduce or abolish the extracellular adenosine deaminase 2 enzyme, the major
    plasma adenosine deaminase. Diagnosis is supported by low (<5% of normal)
    or undetectable ADA2 catalytic activity in plasma or serum. ADA2 is a
    secreted protein with both adenosine-deaminating activity and growth-factor
    activity, so loss of function impairs purine catabolism and ADA2-dependent
    signaling in the vasculature and myeloid compartment.
  biological_processes:
  - preferred_term: adenosine catabolic process
    term:
      id: GO:0006154
      label: adenosine catabolic process
    modifier: DECREASED
  evidence:
  - reference: PMID:24552284
    reference_title: "Early-onset stroke and vasculopathy associated with mutations in ADA2."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Patients had a marked reduction in the levels of ADA2 and ADA2-specific enzyme activity in the blood."
    explanation: >
      Demonstrates that recessive CECR1/ADA2 mutations cause loss of ADA2
      protein and enzyme activity in patients, the primary biochemical lesion.
  - reference: PMID:24552285
    reference_title: "Mutant adenosine deaminase 2 in a polyarteritis nodosa vasculopathy."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Recessive loss-of-function mutations of ADA2, a growth factor that is the major extracellular adenosine deaminase, can cause polyarteritis nodosa vasculopathy with highly varied clinical expression."
    explanation: >
      Establishes ADA2 as the major extracellular adenosine deaminase and a
      growth factor whose loss of function causes the vasculopathy.
  downstream:
  - target: Endothelial Damage and Vasculopathy
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
  - target: Myeloid Inflammatory Dysregulation
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
  - target: Lysosomal DNA Editing and TLR9 Immune Sensing
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
- name: Endothelial Damage and Vasculopathy
  description: >
    Loss of ADA2 compromises endothelial integrity. Biopsies of skin, liver,
    and brain show vasculopathic changes with compromised endothelial
    integrity, endothelial cellular activation, and inflammation. Patient
    monocytes induce damage in cocultured endothelial-cell layers, linking
    myeloid dysregulation to the vascular injury that underlies stroke and
    polyarteritis-nodosa-like vasculitis.
  cell_types:
  - preferred_term: vascular endothelial cell
    term:
      id: CL:0002139
      label: endothelial cell of vascular tree
  biological_processes:
  - preferred_term: inflammatory response
    term:
      id: GO:0006954
      label: inflammatory response
    modifier: INCREASED
  evidence:
  - reference: PMID:24552284
    reference_title: "Early-onset stroke and vasculopathy associated with mutations in ADA2."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Skin, liver, and brain biopsies revealed vasculopathic changes characterized by compromised endothelial integrity, endothelial cellular activation, and inflammation."
    explanation: >
      Direct histopathologic evidence of endothelial injury and vascular
      inflammation in DADA2 patient tissues.
  - reference: PMID:24552284
    reference_title: "Early-onset stroke and vasculopathy associated with mutations in ADA2."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Monocytes from patients induced damage in cocultured endothelial-cell layers."
    explanation: >
      In vitro coculture shows DADA2 patient monocytes directly damage
      endothelium, mechanistically linking myeloid cells to vasculopathy.
  downstream:
  - target: Vascular and Neurologic Manifestations
    causal_link_type: DIRECT
- name: Myeloid Inflammatory Dysregulation
  description: >
    ADA2 deficiency skews monocyte/macrophage differentiation toward a
    proinflammatory state and disrupts neutrophil homeostasis. In a zebrafish
    model, knockdown of the ADA2 homologue caused intracranial hemorrhages and
    neutropenia, phenotypes rescued by wild-type but not mutant human CECR1,
    implicating ADA2 in myeloid and vascular development. Proinflammatory
    cytokines, including TNF, drive the autoinflammatory phenotype, which is why
    TNF inhibition is clinically effective.
  cell_types:
  - preferred_term: monocyte
    term:
      id: CL:0000576
      label: monocyte
  - preferred_term: macrophage
    term:
      id: CL:0000235
      label: macrophage
  - preferred_term: neutrophil
    term:
      id: CL:0000775
      label: neutrophil
  biological_processes:
  - preferred_term: macrophage activation
    term:
      id: GO:0042116
      label: macrophage activation
    modifier: INCREASED
  - preferred_term: tumor necrosis factor production
    term:
      id: GO:0032640
      label: tumor necrosis factor production
    modifier: INCREASED
  evidence:
  - reference: PMID:24552284
    reference_title: "Early-onset stroke and vasculopathy associated with mutations in ADA2."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "Knockdown of a zebrafish ADA2 homologue caused intracranial hemorrhages and neutropenia - phenotypes that were prevented by coinjection with nonmutated (but not with mutated) human CECR1."
    explanation: >
      Model-organism data linking ADA2 loss to hemorrhage and neutropenia and
      confirming the variants are loss-of-function.
  downstream:
  - target: Hematologic Manifestations
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
- name: Vascular and Neurologic Manifestations
  description: >
    Endothelial injury and systemic vasculopathy produce intermittent fevers,
    livedoid rash, early-onset lacunar (ischemic) and hemorrhagic strokes,
    hepatosplenomegaly, hypertension, and cutaneous or systemic polyarteritis
    nodosa.
  evidence:
  - reference: PMID:24552284
    reference_title: "Early-onset stroke and vasculopathy associated with mutations in ADA2."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We observed a syndrome of intermittent fevers, early-onset lacunar strokes and other neurovascular manifestations, livedoid rash, hepatosplenomegaly, and systemic vasculopathy in three unrelated patients."
    explanation: >
      Describes the core inflammatory/vascular clinical syndrome of DADA2.
  downstream:
  - target: Recurrent fever
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
  - target: Livedo racemosa
    causal_link_type: DIRECT
  - target: Stroke
    causal_link_type: DIRECT
  - target: Ischemic stroke
    causal_link_type: DIRECT
  - target: Intracranial hemorrhage
    causal_link_type: DIRECT
  - target: Polyarteritis nodosa
    causal_link_type: DIRECT
  - target: Hepatosplenomegaly
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
  - target: Hypertension
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
  - target: Arthritis
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
- name: Hematologic Manifestations
  description: >
    Bone marrow failure and cytopenias are a major DADA2 phenotype group,
    including pure red cell aplasia, immune-mediated neutropenia, and
    pancytopenia. These hematologic features respond variably to anti-TNF
    therapy and may require hematopoietic stem cell transplantation.
  evidence:
  - reference: PMID:35095905
    reference_title: "The Spectrum of the Deficiency of Adenosine Deaminase 2: An Observational Analysis of a 60 Patient Cohort."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Hematologic findings including pure red cell aplasia (PRCA), immune-mediated neutropenia, and pancytopenia were observed in half of patients."
    explanation: >
      Cohort evidence that hematologic manifestations are a prominent,
      frequent DADA2 phenotype.
  downstream:
  - target: Immunodeficiency
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
  - target: Decreased circulating immunoglobulin concentration
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
  - target: Pure red cell aplasia
    causal_link_type: DIRECT
  - target: Decreased total neutrophil count
    causal_link_type: DIRECT
  - target: Pancytopenia
    causal_link_type: DIRECT
  - target: Thrombocytopenia
    causal_link_type: DIRECT
  - target: Decreased total lymphocyte count
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
- name: Lysosomal DNA Editing and TLR9 Immune Sensing
  description: >
    An emerging (2024) mechanistic model expands the classical extracellular
    adenosine paradigm. ADA2 localizes within lysosomes, where it acts as a
    deoxyadenosine deaminase on DNA, converting deoxyadenosine (dA) to
    deoxyinosine (dI). This dA-to-dI editing modulates lysosomal innate immune
    sensing of nucleic acids through Toll-like receptor 9 (TLR9), providing a
    cell-intrinsic mechanism that may drive the type I interferon and TNF
    pathway activation seen in DADA2 (a recognized type 1 interferonopathy of
    childhood).
  biological_processes:
  - preferred_term: toll-like receptor 9 signaling pathway
    term:
      id: GO:0034162
      label: toll-like receptor 9 signaling pathway
    modifier: ABNORMAL
  - preferred_term: type I interferon production
    term:
      id: GO:0032606
      label: type I interferon production
    modifier: INCREASED
  evidence:
  - reference: PMID:39441717
    reference_title: "ADA2 is a lysosomal deoxyadenosine deaminase acting on DNA involved in regulating TLR9-mediated immune sensing of DNA."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "we demonstrate that dA-to-dI editing of DNA molecules and ADA2 regulate lysosomal immune sensing of nucleic acids (NAs) by modulating Toll-like receptor 9 (TLR9) activation."
    explanation: >
      Establishes the emerging lysosomal DNA-editing / TLR9 mechanism that may
      underlie the innate-immune activation of DADA2, complementing the
      extracellular-adenosine model.
  downstream:
  - target: Myeloid Inflammatory Dysregulation
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
phenotypes:
- category: Phenotypic abnormality
  name: Recurrent fever
  description: Intermittent inflammatory fevers are a cardinal feature of DADA2.
  phenotype_term:
    preferred_term: Recurrent fever
    term:
      id: HP:0001954
      label: Recurrent fever
  evidence:
  - reference: PMID:24552284
    reference_title: "Early-onset stroke and vasculopathy associated with mutations in ADA2."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We observed a syndrome of intermittent fevers, early-onset lacunar strokes and other neurovascular manifestations, livedoid rash, hepatosplenomegaly, and systemic vasculopathy in three unrelated patients."
    explanation: Intermittent fevers were a defining feature of the initial DADA2 cohort.
- category: Phenotypic abnormality
  name: Livedo racemosa
  description: Livedo racemosa/reticularis is the characteristic cutaneous manifestation.
  phenotype_term:
    preferred_term: Livedo racemosa
    term:
      id: HP:0033260
      label: Livedo racemosa
  evidence:
  - reference: PMID:35095905
    reference_title: "The Spectrum of the Deficiency of Adenosine Deaminase 2: An Observational Analysis of a 60 Patient Cohort."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "first described in patients with fevers, recurrent strokes, livedo racemosa, and polyarteritis nodosa in 2014"
    explanation: Livedo racemosa is a cardinal cutaneous feature of DADA2.
- category: Phenotypic abnormality
  name: Stroke
  description: Early-onset recurrent lacunar (ischemic) and hemorrhagic strokes, usually before age ten.
  phenotype_term:
    preferred_term: Stroke
    term:
      id: HP:0001297
      label: Stroke
    # frequency assigned as a clinical estimate (Pattern D, frequency-evidence-guidelines.md):
    # stroke is described as a cardinal/core feature of DADA2 across the founding cohort
    # (PMID:24552284) and the 60-patient observational cohort (PMID:35095905), but no exact
    # percentage is reported in the cited abstracts.
  frequency: FREQUENT
  evidence:
  - reference: PMID:24552284
    reference_title: "Early-onset stroke and vasculopathy associated with mutations in ADA2."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Loss-of-function mutations in CECR1 were associated with a spectrum of vascular and inflammatory phenotypes, ranging from early-onset recurrent stroke to systemic vasculopathy or vasculitis."
    explanation: Establishes early-onset recurrent stroke as a core DADA2 phenotype.
- category: Phenotypic abnormality
  name: Ischemic stroke
  description: Lacunar ischemic strokes affecting deep brain structures, often recurrent.
  phenotype_term:
    preferred_term: Ischemic (lacunar) stroke
    term:
      id: HP:0002140
      label: Ischemic stroke
  evidence:
  - reference: PMID:24552284
    reference_title: "Early-onset stroke and vasculopathy associated with mutations in ADA2."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We observed a syndrome of intermittent fevers, early-onset lacunar strokes and other neurovascular manifestations, livedoid rash, hepatosplenomegaly, and systemic vasculopathy in three unrelated patients."
    explanation: Documents early-onset lacunar (ischemic) strokes in DADA2.
- category: Phenotypic abnormality
  name: Intracranial hemorrhage
  description: Hemorrhagic strokes / intracranial hemorrhage can occur in addition to ischemic events.
  phenotype_term:
    preferred_term: Hemorrhagic stroke / intracranial hemorrhage
    term:
      id: HP:0002170
      label: Intracranial hemorrhage
  evidence:
  - reference: PMID:24552284
    reference_title: "Early-onset stroke and vasculopathy associated with mutations in ADA2."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "Knockdown of a zebrafish ADA2 homologue caused intracranial hemorrhages and neutropenia - phenotypes that were prevented by coinjection with nonmutated (but not with mutated) human CECR1."
    explanation: >
      Zebrafish model recapitulates the intracranial hemorrhage phenotype seen
      in DADA2 patients (hemorrhagic strokes are part of the human phenotype
      per the GeneReviews chapter).
  - reference: PMID:31393689
    reference_title: "Adenosine Deaminase 2 Deficiency."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "manifest as early-onset ischemic (lacunar) and/or hemorrhagic strokes, or as"
    explanation: >
      GeneReviews documents hemorrhagic strokes / intracranial hemorrhage as part
      of the human DADA2 vasculitis phenotype, providing human clinical support
      alongside the zebrafish model.
- category: Phenotypic abnormality
  name: Polyarteritis nodosa
  description: Cutaneous or systemic polyarteritis-nodosa-like medium-vessel vasculitis.
  phenotype_term:
    preferred_term: Polyarteritis nodosa
    term:
      id: HP:6000658
      label: Medium vessel vasculitis
  evidence:
  - reference: PMID:24552285
    reference_title: "Mutant adenosine deaminase 2 in a polyarteritis nodosa vasculopathy."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "In all the families, vasculitis was caused by recessive mutations in CECR1, the gene encoding adenosine deaminase 2 (ADA2)."
    explanation: >
      DADA2 was independently identified as the cause of familial polyarteritis
      nodosa vasculitis. The ontology term Medium vessel vasculitis (HP:6000658)
      precisely captures the PAN-type vasculitis, whose ontology definition
      explicitly cites polyarteritis nodosa.
- category: Phenotypic abnormality
  name: Hepatosplenomegaly
  description: Enlargement of the liver and spleen is commonly observed.
  phenotype_term:
    preferred_term: Hepatosplenomegaly
    term:
      id: HP:0001433
      label: Hepatosplenomegaly
  evidence:
  - reference: PMID:24552284
    reference_title: "Early-onset stroke and vasculopathy associated with mutations in ADA2."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We observed a syndrome of intermittent fevers, early-onset lacunar strokes and other neurovascular manifestations, livedoid rash, hepatosplenomegaly, and systemic vasculopathy in three unrelated patients."
    explanation: Hepatosplenomegaly was present in the founding DADA2 cohort.
- category: Phenotypic abnormality
  name: Immunodeficiency
  description: >
    Immune dysregulation with hypogammaglobulinemia, low class-switched memory
    B cells, and inadequate vaccine responses; infections are nonetheless rare.
  phenotype_term:
    preferred_term: Immunodeficiency
    term:
      id: HP:0002721
      label: Immunodeficiency
  evidence:
  - reference: PMID:35095905
    reference_title: "The Spectrum of the Deficiency of Adenosine Deaminase 2: An Observational Analysis of a 60 Patient Cohort."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Evidence of immune dysregulation was commonly observed, including hypogammaglobulinemia, absent to low class-switched memory B cells, and inadequate response to vaccination."
    explanation: Cohort evidence of the immunodeficiency/immune-dysregulation phenotype.
- category: Phenotypic abnormality
  name: Decreased circulating immunoglobulin concentration
  description: Hypogammaglobulinemia is part of the immune-dysregulation phenotype.
  phenotype_term:
    preferred_term: Hypogammaglobulinemia
    term:
      id: HP:0004313
      label: Decreased circulating immunoglobulin concentration
  evidence:
  - reference: PMID:35095905
    reference_title: "The Spectrum of the Deficiency of Adenosine Deaminase 2: An Observational Analysis of a 60 Patient Cohort."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Evidence of immune dysregulation was commonly observed, including hypogammaglobulinemia, absent to low class-switched memory B cells, and inadequate response to vaccination."
    explanation: Documents hypogammaglobulinemia in the DADA2 cohort.
- category: Phenotypic abnormality
  name: Pure red cell aplasia
  description: Pure red cell aplasia is a recognized hematologic manifestation.
  phenotype_term:
    preferred_term: Pure red cell aplasia
    term:
      id: HP:0012410
      label: Pure red cell aplasia
  evidence:
  - reference: PMID:35095905
    reference_title: "The Spectrum of the Deficiency of Adenosine Deaminase 2: An Observational Analysis of a 60 Patient Cohort."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Hematologic findings including pure red cell aplasia (PRCA), immune-mediated neutropenia, and pancytopenia were observed in half of patients."
    explanation: Pure red cell aplasia documented as a DADA2 hematologic phenotype.
- category: Phenotypic abnormality
  name: Decreased total neutrophil count
  description: Immune-mediated neutropenia is a common hematologic finding.
  phenotype_term:
    preferred_term: Neutropenia
    term:
      id: HP:0001875
      label: Decreased total neutrophil count
  evidence:
  - reference: PMID:35095905
    reference_title: "The Spectrum of the Deficiency of Adenosine Deaminase 2: An Observational Analysis of a 60 Patient Cohort."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Hematologic findings including pure red cell aplasia (PRCA), immune-mediated neutropenia, and pancytopenia were observed in half of patients."
    explanation: Documents immune-mediated neutropenia in DADA2.
- category: Phenotypic abnormality
  name: Pancytopenia
  description: Pancytopenia / bone marrow failure can occur in DADA2.
  phenotype_term:
    preferred_term: Pancytopenia
    term:
      id: HP:0001876
      label: Pancytopenia
  evidence:
  - reference: PMID:35095905
    reference_title: "The Spectrum of the Deficiency of Adenosine Deaminase 2: An Observational Analysis of a 60 Patient Cohort."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Hematologic findings including pure red cell aplasia (PRCA), immune-mediated neutropenia, and pancytopenia were observed in half of patients."
    explanation: Pancytopenia documented as a DADA2 hematologic phenotype.
- category: Phenotypic abnormality
  name: Thrombocytopenia
  description: Thrombocytopenia is among the hematologic manifestations of DADA2.
  phenotype_term:
    preferred_term: Thrombocytopenia
    term:
      id: HP:0001873
      label: Thrombocytopenia
  evidence:
  - reference: PMID:31393689
    reference_title: "Adenosine Deaminase 2 Deficiency."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "lymphopenia, neutropenia, pure red cell aplasia, thrombocytopenia, or pancytopenia"
    explanation: GeneReviews lists thrombocytopenia among the hematologic disorders of DADA2.
- category: Phenotypic abnormality
  name: Decreased total lymphocyte count
  description: Lymphopenia is among the hematologic/immune manifestations.
  phenotype_term:
    preferred_term: Lymphopenia
    term:
      id: HP:0001888
      label: Decreased total lymphocyte count
  evidence:
  - reference: PMID:31393689
    reference_title: "Adenosine Deaminase 2 Deficiency."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "lymphopenia, neutropenia, pure red cell aplasia, thrombocytopenia, or pancytopenia"
    explanation: GeneReviews lists lymphopenia among the hematologic disorders of DADA2.
- category: Phenotypic abnormality
  name: Hypertension
  description: Hypertension is frequently observed, often related to vasculopathy.
  phenotype_term:
    preferred_term: Hypertension
    term:
      id: HP:0000822
      label: Hypertension
  evidence:
  - reference: PMID:31393689
    reference_title: "Adenosine Deaminase 2 Deficiency."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Hypertension and hepatosplenomegaly are often found."
    explanation: GeneReviews notes hypertension is often found in DADA2.
- category: Phenotypic abnormality
  name: Arthritis
  description: Musculoskeletal inflammation including arthritis, arthralgia, myalgia, and myositis.
  phenotype_term:
    preferred_term: Arthritis
    term:
      id: HP:0001369
      label: Arthritis
  evidence:
  - reference: PMID:31393689
    reference_title: "Adenosine Deaminase 2 Deficiency."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "musculoskeletal involvement (myalgia/arthralgia, arthritis, myositis)"
    explanation: GeneReviews documents musculoskeletal involvement including arthritis in DADA2.
genetic:
- name: ADA2 biallelic loss of function
  gene_term:
    preferred_term: ADA2
    term:
      id: hgnc:1839
      label: ADA2
  association: Pathogenic Variants
  inheritance:
  - name: Autosomal recessive
  evidence:
  - reference: PMID:24552285
    reference_title: "Mutant adenosine deaminase 2 in a polyarteritis nodosa vasculopathy."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "In all the families, vasculitis was caused by recessive mutations in CECR1, the gene encoding adenosine deaminase 2 (ADA2)."
    explanation: >
      Establishes recessive (biallelic) CECR1/ADA2 loss-of-function variants
      as the cause of DADA2. CECR1 is the former symbol for ADA2.
  - reference: PMID:24552284
    reference_title: "Early-onset stroke and vasculopathy associated with mutations in ADA2."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "All nine patients carried recessively inherited mutations in CECR1 (cat eye syndrome chromosome region, candidate 1), encoding adenosine deaminase 2 (ADA2), that were predicted to be deleterious; these mutations were rare or absent in healthy controls."
    explanation: Independent confirmation of recessive deleterious CECR1/ADA2 variants in patients.
treatments:
- name: Anti-TNF Therapy
  description: >
    Anti-tumor necrosis factor (TNF) agents (etanercept, adalimumab, golimumab,
    infliximab, certolizumab) are the drugs of choice for symptomatic and
    asymptomatic individuals with biallelic ADA2 pathogenic variants. They
    prevent and eliminate autoinflammatory/vasculitic manifestations and reduce
    the risk of ischemic stroke. Hematologic and immune features respond more
    variably, and anti-TNF agents have little effect on severe bone marrow
    failure.
  treatment_term:
    preferred_term: anti-TNF therapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: adalimumab
      term:
        id: NCIT:C65216
        label: Adalimumab
    - preferred_term: etanercept
      term:
        id: NCIT:C2381
        label: Etanercept
  evidence:
  - reference: PMID:35095905
    reference_title: "The Spectrum of the Deficiency of Adenosine Deaminase 2: An Observational Analysis of a 60 Patient Cohort."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We significantly extended our experience using anti-TNF agents, with no strokes observed in 2026 patient months on TNF inhibitors."
    explanation: >
      Cohort evidence that anti-TNF therapy prevents stroke in DADA2, the
      mainstay of treatment.
  - reference: PMID:33420503
    reference_title: "Anti-tumour necrosis factor treatment for the prevention of ischaemic events in patients with deficiency of adenosine deaminase 2 (DADA2)."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Anti-TNF treatment significantly reduced the incidence of ischaemic events and other vasculitic manifestations of DADA2, but was not effective for immunodeficiency or bone marrow failure."
    explanation: >
      Multicenter retrospective study quantifying that anti-TNF therapy
      prevents ischemic events and vasculitis but not the hematologic/immune
      phenotype, consistent with anti-TNF as first-line disease-modifying
      therapy.
- name: Hematopoietic Stem Cell Transplantation
  description: >
    Allogeneic hematopoietic cell transplantation (HCT) can correct severe
    hematologic and immunologic DADA2 disease that is refractory to anti-TNF
    therapy; transplanted patients in the NIH cohort discontinued anti-TNF
    therapy after engraftment.
  therapeutic_modality: CELL_THERAPY
  treatment_term:
    preferred_term: hematopoietic stem cell transplantation
    term:
      id: MAXO:0000747
      label: hematopoietic stem cell transplantation
  evidence:
  - reference: PMID:35095905
    reference_title: "The Spectrum of the Deficiency of Adenosine Deaminase 2: An Observational Analysis of a 60 Patient Cohort."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "All transplanted patients are still alive and have discontinued anti-TNF therapy."
    explanation: >
      Cohort evidence that allogeneic HCT can be curative for DADA2 hematologic
      / immune disease, allowing discontinuation of anti-TNF therapy.
  - reference: PMID:34324127
    reference_title: "Hematopoietic Cell Transplantation Cures Adenosine Deaminase 2 Deficiency: Report on 30 Patients."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "HCT was an effective treatment for DADA2, successfully reversing the refractory cytopenia, as well as the vasculopathy and immunodeficiency."
    explanation: >-
      International 30-patient series showing HCT reverses refractory
      cytopenia, vasculopathy, and immunodeficiency, establishing HCT as a
      definitive cure for DADA2.
📚

References & Deep Research

References

1
PMID:31393689
Adenosine Deaminase 2 Deficiency.
No top-level findings curated for this source.

Deep Research

1
Falcon ▸
Deficiency of Adenosine Deaminase 2 (DADA2) — Comprehensive Disease Characteristics Report
Edison Scientific Literature 30 citations 2026-06-03T17:11:26.055582

Deficiency of Adenosine Deaminase 2 (DADA2) — Comprehensive Disease Characteristics Report

Executive summary

Deficiency of adenosine deaminase 2 (DADA2) is an autosomal recessive inborn error of immunity caused by biallelic loss-of-function variants in ADA2 (formerly CECR1) and characterized by a triad of (i) vasculitis/vasculopathy with early-onset ischemic and hemorrhagic strokes and cutaneous vasculopathy, (ii) immune dysregulation/immunodeficiency, and (iii) hematologic disease including cytopenias and bone marrow failure. Large cohorts and meta-reviews show substantial neurologic burden (≈50% have a neurologic event), strong prevention of ischemic events with TNF inhibition, and curative potential of hematopoietic cell transplantation (HCT) for refractory hematologic/immunologic phenotypes. Recent 2024 mechanistic work implicates lysosomal ADA2 in DNA editing (dA→dI) and TLR9-mediated nucleic-acid sensing, expanding the classical extracellular-adenosine model. (dzhus2023anarrativereview pages 1-2, wouters2024humanada2deficiency pages 1-3, hashem2021hematopoieticcelltransplantation pages 1-2, cooray2021antitumournecrosisfactor pages 1-4, greinertollersrud2024ada2isa pages 1-3)

Category Item Summary Key quantitative details Citation placeholders
Disease identifiers Preferred name Deficiency of adenosine deaminase 2; commonly abbreviated DADA2 First described in 2014; complex systemic autoinflammatory/inborn error of immunity phenotype [CITATION]
Disease identifiers Standard identifiers MONDO: MONDO_0014306; OMIM: 615688 OpenTargets links MONDO_0014306 to ADA2 as the associated target [CITATION]
Disease identifiers Common synonyms Human ADA2 deficiency; ADA2 deficiency; CECR1 deficiency; deficiency of adenosine deaminase type 2 ADA2 was formerly named CECR1 [CITATION]
Genetics / inheritance Causal gene ADA2 (formerly CECR1) encodes adenosine deaminase 2 Biallelic deleterious/loss-of-function variants cause disease [CITATION]
Genetics / inheritance Inheritance Autosomal recessive Homozygous or compound heterozygous pathogenic variants reported [CITATION]
Genetics / inheritance Variant spectrum Most reported variants are missense, but splice/intronic/structural variants also occur 2024 review notes >400 cases reported overall [CITATION]
Phenotype domains Major domains Three overlapping domains: inflammatory/vascular, immune dysregulatory, hematologic Most patients show overlap rather than a single isolated phenotype [CITATION]
Phenotype domains Inflammatory / vascular Cutaneous manifestations, livedo racemosa/reticularis, PAN-like vasculopathy, stroke, end-organ vasculitis In Barron 2022, cardinal features were cutaneous manifestations and stroke [CITATION]
Phenotype domains Immune dysregulatory Hypogammaglobulinemia, low/absent class-switched memory B cells, poor vaccine responses Barron 2022 notes immune dysregulation was common, but infectious complications were exceedingly rare in that cohort [CITATION]
Phenotype domains Hematologic PRCA, immune-mediated neutropenia, thrombocytopenia, pancytopenia, bone marrow failure Barron 2022: hematologic findings were seen in ~50% of patients [CITATION]
Neurologic burden Any neurological event Neurologic involvement is a major disease burden and can be initial or sole presentation Dzhus 2023 review: 50.3% had ≥1 neurological event; initial manifestation in 5.7%; sole manifestation in 0.6% [CITATION]
Neurologic burden Cerebrovascular events Stroke is the dominant neurologic manifestation Among patients with neurologic manifestations, 77.5% had ≥1 cerebrovascular accident; 35.9% had multiple stroke episodes [CITATION]
Neurologic burden Stroke localization Lacunar ischemic strokes predominate, with characteristic anatomic distribution Brainstem involvement 37.3% and deep gray matter involvement 41.6% of ischemic strokes in the review [CITATION]
Age / onset Typical onset Usually childhood onset, but adult-onset cases occur Mean age of onset in reviewed neurologic literature was ~7 years; 2023 review notes onset often by age 10 [CITATION]
Population statistics Prevalence estimate Rare disease; likely underrecognized 2024 review estimated prevalence at ~1:222,000 and carrier frequency ~1:236 using residual activity modeling [CITATION]
Diagnostics Enzyme activity testing Low or absent plasma/serum ADA2 enzymatic activity is a core diagnostic modality Functional testing is especially useful when variants are uncertain or urgent diagnosis is needed [CITATION]
Diagnostics Molecular diagnosis Confirm by biallelic pathogenic ADA2 variants via single-gene testing, panel, WES/WGS as appropriate Diagnosis can also require follow-up for splice, intronic, or structural variants [CITATION]
Diagnostics Practical diagnostic statement Current reviews recommend combining genetics with enzyme activity Identification of biallelic variants plus severely diminished/absent ADA2 activity is considered diagnostic [CITATION]
Treatment Anti-TNF agents First-line disease-modifying therapy for vasculitic/ischemic phenotype; not reliably effective for marrow failure/immunodeficiency Includes etanercept, infliximab, adalimumab in published series [CITATION]
Treatment outcomes Anti-TNF effectiveness (multicenter) Major reduction in ischemic events after anti-TNF treatment Cooray 2021: median ischemic event rate fell from 2.37 per 100 patient-months pre-treatment to 0.00 per 100 patient-months post-treatment (p<0.0001); PVAS fell from 20/63 to 2/63 [CITATION]
Treatment outcomes Anti-TNF effectiveness (NIH cohort) Sustained stroke prevention signal in longitudinal cohort Barron 2022: no strokes observed during 2026–2027 patient-months on TNF inhibitors [CITATION]
Treatment limitations Anti-TNF nonresponse domains Hematologic failure and severe immunodeficiency often persist despite TNF blockade Cooray 2021 and other cohorts report these phenotypes may require transplantation [CITATION]
Curative therapy Allogeneic HCT / HSCT Considered definitive/curative especially for bone marrow failure, severe cytopenia, severe immunodeficiency Reverses hematologic, immunologic, and vascular disease in many reported patients [CITATION]
Curative therapy outcomes International HCT cohort Strong survival and biochemical correction after transplantation Hashem 2021: 30 patients, 38 HCTs, median age 9 years; 2-year OS 97%; 2-year GvHD-free relapse-free survival 73%; ADA2 activity normalized in 16/17 tested; 6 patients required >1 HCT [CITATION]
Real-world implementation Cohort examples National and multicenter cohorts confirm pediatric predominance and anti-TNF responsiveness for vasculopathy Brazil 2023: 18 patients, pediatric onset median 5 years, anti-TNF responses favorable; Iran 2023: 11 patients, strokes in 64%, anti-TNF response in 8 treated patients [CITATION]

Table: This table condenses identifiers, genetics, core phenotype domains, diagnostics, and major treatment outcomes for DADA2. It is useful as a structured evidence scaffold for a disease knowledge base entry and can be supplemented with formal citations in the final report.

Domain Phenotype Barron 2022 NIH cohort (n=58 evaluated) Dzhus 2023 review (n=628) Melo 2023 Brazil (n=18) Ashari 2023 Iran (n=11) Suggested HPO term(s) Suggested UBERON anatomy Evidence source / citation placeholder
Skin / vascular Livedo racemosa / reticularis 43/58 (74%) livedo racemosa Included as core phenotype; no pooled % in excerpt 11/18 (62%) livedo reticularis 11/11 (100%) livedo racemosa/reticularis HP:0005344 Livedo reticularis; livedo racemosa (term name if preferred) UBERON:0002097 skin Barron cohort; Dzhus review; Brazil and Iran cohorts (barron2022thespectrumof pages 3-4, barron2022thespectrumof pages 4-7, dzhus2023anarrativereview pages 1-2, melo2023abraziliannationwide pages 4-6, ashari2023acaseseries pages 1-2)
Skin / vascular Cutaneous ulcers / ulcerating lesions 3/58 (5%) ulcerating lesions; additional severe digital ulceration described Ulcerations/cutaneous necrosis listed; no pooled % in excerpt GI/skin ulcers reported; explicit skin-ulcer % not provided Not specified HP:0200042 Skin ulcer; HP:0008066 Cutaneous necrosis UBERON:0002097 skin; distal digit (term name) Barron cohort; 2024 review; Brazil cohort (barron2022thespectrumof pages 3-4, barron2022thespectrumof pages 8-10, wouters2024humanada2deficiency pages 1-3, melo2023abraziliannationwide pages 4-6)
Skin / vascular Raynaud phenomenon 13/58 (22%) Mentioned in broader DADA2 literature; no pooled % in excerpt Not specified Not specified HP:0001945 Raynaud phenomenon UBERON:0002398 hand; UBERON:0002104 foot; peripheral vasculature Barron cohort (barron2022thespectrumof pages 3-4)
CNS Any stroke / cerebrovascular event 25/58 (43%) total strokes; ischemic 24/58 (41%), hemorrhagic 7/58 (12%) Neurological event in 50.3%; among neurological cases, 77.5% had cerebrovascular accident Neurologic involvement 16/18 (89%); ischemic stroke 11/18 (61%); hemorrhagic stroke 1/18 (5%) 7/11 (64%) strokes HP:0001297 Stroke; HP:0002140 Ischemic stroke; intracranial hemorrhage / cerebral hemorrhage (term name) UBERON:0000955 brain; cerebral vasculature (term name) Barron cohort; Dzhus review; Brazil and Iran cohorts (barron2022thespectrumof pages 3-4, barron2022thespectrumof pages 4-7, dzhus2023anarrativereview pages 1-2, melo2023abraziliannationwide pages 4-6, ashari2023acaseseries pages 1-2)
CNS Ischemic stroke 24/58 (41%) Lacunar strokes most common; 35.9% had multiple strokes 11/18 (61%) Included within 7/11 stroke total; ischemic subtype not explicitly separated in excerpt HP:0002140 Ischemic stroke; lacunar stroke (term name) UBERON:0000955 brain Barron cohort; Dzhus review; Brazil and Iran cohorts (barron2022thespectrumof pages 3-4, barron2022thespectrumof pages 4-7, dzhus2023anarrativereview pages 1-2, melo2023abraziliannationwide pages 4-6, ashari2023acaseseries pages 1-2)
CNS Hemorrhagic stroke 7/58 (12%) Early-onset hemorrhagic stroke recognized; no pooled % in excerpt 1/18 (5%) Not specified separately HP:0001342 Intracranial hemorrhage; cerebral hemorrhage (term name) UBERON:0000955 brain Barron cohort; Dzhus review; Brazil cohort (barron2022thespectrumof pages 3-4, barron2022thespectrumof pages 4-7, dzhus2023anarrativereview pages 1-2, melo2023abraziliannationwide pages 4-6)
CNS anatomy Brainstem / deep gray matter predilection ~3/4 of strokes in brainstem, cerebellum, deep brain nuclei Brainstem 37.3% and deep gray matter 41.6% of ischemic strokes Not quantified Not quantified HP: brainstem lesion / deep gray matter infarction (term names) UBERON:0002298 brainstem; deep gray matter / basal ganglion / thalamus (term names) Barron cohort; Dzhus review (barron2022thespectrumof pages 4-7, dzhus2023anarrativereview pages 1-2, wouters2024humanada2deficiency pages 1-3)
Hematologic Cytopenias (any) 28/58 (48%) Cytopenias part of phenotype; no pooled % in excerpt Persistent neutropenia described in individual cases; no overall cytopenia % in excerpt PRCA in 1/11; broader cytopenias recognized but no cohort-wide % except PRCA HP:0001871 Abnormality of blood and blood-forming tissues; cytopenia (term name) UBERON:0002371 bone marrow; blood Barron cohort; review; Brazil/Iran cohorts (barron2022thespectrumof pages 4-7, wouters2024humanada2deficiency pages 1-3, melo2023abraziliannationwide pages 4-6, ashari2023acaseseries pages 1-2)
Hematologic Pure red cell aplasia (PRCA) Mentioned as key hematologic feature; frequency not explicit in excerpt Recognized phenotype; no pooled % in excerpt Not specified in excerpt 1/11 (9%) PRCA HP:0004810 Pure red cell aplasia UBERON:0002371 bone marrow Barron cohort; 2024 review; Iran cohort (barron2022thespectrumof pages 1-2, wouters2024humanada2deficiency pages 1-3, ashari2023acaseseries pages 1-2)
Hematologic Pancytopenia 6/58 (10%) Listed as part of phenotype; no pooled % in excerpt Not specified Not specified HP:0001876 Pancytopenia UBERON:0002371 bone marrow; blood Barron cohort; 2024 review (barron2022thespectrumof pages 4-7, wouters2024humanada2deficiency pages 1-3)
Hematologic Severe anemia / neutropenia / thrombocytopenia Severe anemia 7/58 (12%); immune neutropenia 9/58 (16%); thrombocytopenia 5/58 (9%) Anemia, neutropenia, thrombocytopenia recognized; no pooled % in excerpt Persistent neutropenia in at least one case; no summary % in excerpt Not specified beyond PRCA case HP:0001903 Anemia; HP:0001875 Neutropenia; HP:0001873 Thrombocytopenia UBERON:0000178 blood; UBERON:0002371 bone marrow Barron cohort; reviews/cohorts (barron2022thespectrumof pages 4-7, wouters2024humanada2deficiency pages 1-3, melo2023abraziliannationwide pages 4-6, ashari2023acaseseries pages 1-2)
Immunologic Hypogammaglobulinemia / quantitative immunoglobulin abnormality 38/58 (66%) abnormal immunoglobulins Common feature; ranges from mild hypo-Ig to CVID-like disease Hypogammaglobulinemia described in P1, P2, P16, P18 (4/18 noted in excerpt) 2/11 (18%) decreased immunoglobulin levels HP:0004313 Decreased circulating immunoglobulin level; HP:0002721 Hypogammaglobulinemia Blood / plasma (UBERON term name if needed) Barron cohort; 2024 review; Brazil and Iran cohorts (barron2022thespectrumof pages 3-4, barron2022thespectrumof pages 8-10, wouters2024humanada2deficiency pages 1-3, melo2023abraziliannationwide pages 4-6, ashari2023acaseseries pages 1-2)
Immunologic Low IgG 32/58 (55%) Recognized; no pooled % in excerpt Not specified Not specified HP:0012147 Decreased IgG level Blood / plasma Barron cohort (barron2022thespectrumof pages 3-4, barron2022thespectrumof pages 8-10)
Immunologic Low IgM 36/58 (62%) Recognized; no pooled % in excerpt Not specified Not specified HP:0012149 Decreased IgM level Blood / plasma Barron cohort (barron2022thespectrumof pages 3-4, barron2022thespectrumof pages 8-10)
Immunologic Low IgA 25/58 (43%) Recognized; no pooled % in excerpt Not specified Not specified HP:0012148 Decreased IgA level Blood / plasma Barron cohort (barron2022thespectrumof pages 3-4, barron2022thespectrumof pages 8-10)
Immunologic Low class-switched memory B cells 32/47 (68%) Reduced memory B cells emphasized; no pooled % in excerpt Not specified Not specified Low class-switched memory B cells (term name) CL:0000788 memory B cell Barron cohort; 2024 review (barron2022thespectrumof pages 4-7, barron2022thespectrumof pages 8-10, wouters2024humanada2deficiency pages 1-3)
Visceral Hepatomegaly / splenomegaly / hepatosplenomegaly Hepatomegaly 29/58 (50%); splenomegaly 31/58 (53%); hepatosplenomegaly 22/58 (38%) Lymphadenopathy/hepatosplenomegaly in up to 30% Hepatomegaly with splenomegaly 4/18 (23%); isolated splenomegaly 2/18 (12%) Not specified in excerpt HP:0002240 Hepatomegaly; HP:0001744 Splenomegaly UBERON:0002107 liver; UBERON:0002106 spleen Barron cohort; 2024 review; Brazil cohort (barron2022thespectrumof pages 3-4, wouters2024humanada2deficiency pages 1-3, melo2023abraziliannationwide pages 4-6)
Visceral Portal hypertension 7/58 (12%) Non-cirrhotic portal hypertension described Not specified Not specified HP:0001406 Portal hypertension UBERON:0002107 liver; portal venous system (term name) Barron cohort; 2024 review (barron2022thespectrumof pages 3-4, wouters2024humanada2deficiency pages 1-3)
Visceral / renal Renal cortical lesions 13/58 (22%) Kidney involvement recognized; no pooled % in excerpt Not specified Not specified Renal cortical lesion (term name); HP:0000107 Renal cyst? (do not use if uncertain) UBERON:0001225 kidney; renal cortex (term name) Barron cohort; Dzhus review (barron2022thespectrumof pages 3-4, dzhus2023anarrativereview pages 1-2)
Visceral / GI Colitis / gastrointestinal ulcers Not specifically quantified in NIH excerpt Intestinal involvement, abdominal pain, bowel perforation recognized GI involvement 8/18 (45%); abdominal pain 8/18 (45%); colitis/GI ulcers 2/18 (11%) Not specified HP:0002012 Abnormality of the gastrointestinal tract; colitis / gastrointestinal ulceration (term names) UBERON:0002108 small intestine; UBERON:0001155 colon; GI mucosa (term names) Dzhus review; Brazil cohort (dzhus2023anarrativereview pages 1-2, melo2023abraziliannationwide pages 4-6)

Table: This table summarizes major DADA2 phenotypes across key cohorts and reviews, with best-effort ontology mappings to HPO and UBERON terms. It is useful for structured knowledge-base curation of phenotype prevalence, affected anatomy, and ontology alignment.

1. Disease information

1.1 What is the disease? (concise overview)

DADA2 is a monogenic systemic autoinflammatory/vasculopathic disorder and inborn error of immunity caused by biallelic ADA2 loss-of-function variants, classically presenting with livedo racemosa/reticularis, polyarteritis nodosa (PAN)-like vasculitis, and recurrent lacunar ischemic strokes (often in early childhood), with expanding recognition of immune dysregulation and bone marrow failure phenotypes. (barron2022thespectrumof pages 1-2, wouters2024humanada2deficiency pages 1-3, dzhus2023anarrativereview pages 1-2)

1.2 Key identifiers

  • MONDO: MONDO_0014306 (“deficiency of adenosine deaminase 2”). (OpenTargets Search: Deficiency of adenosine deaminase 2,DADA2-ADA2,CECR1)
  • OMIM: 615688 (noted in a multinational HCT outcome cohort). (hashem2021hematopoieticcelltransplantation pages 1-2)
  • Gene/target: ADA2 (ENSG00000093072). (OpenTargets Search: Deficiency of adenosine deaminase 2,DADA2-ADA2,CECR1)

Not available in retrieved sources: Orphanet ID, ICD-10/ICD-11 codes, MeSH identifier. These should be added from OMIM/Orphanet/ICD/MeSH directly in a follow-up curation pass.

1.3 Synonyms / alternative names

  • Human ADA2 deficiency
  • ADA2 deficiency
  • CECR1 deficiency
  • Deficiency of adenosine deaminase type 2 (ADA2 was formerly called CECR1). (wouters2024humanada2deficiency pages 1-3, hashem2021hematopoieticcelltransplantation pages 1-2)

1.4 Evidence source type

Evidence in this report derives from: - Aggregated cohorts and multicenter studies (NIH 60-patient cohort; Brazilian 18-patient cohort; multicenter anti-TNF and HCT outcome studies). (barron2022thespectrumof pages 1-2, melo2023abraziliannationwide pages 1-2, cooray2021antitumournecrosisfactor pages 1-4, hashem2021hematopoieticcelltransplantation pages 1-2) - Systematic/narrative literature review (628 reported patients). (dzhus2023anarrativereview pages 1-2, wouters2024humanada2deficiency pages 1-3) - Mechanistic primary research (Cell Reports 2024; zebrafish model 2024). (greinertollersrud2024ada2isa pages 1-3, brix2024ada2regulatesinflammation pages 1-2)

2. Etiology

2.1 Disease causal factors

Primary cause: biallelic loss-of-function variants in ADA2 (formerly CECR1) leading to absent or markedly reduced ADA2 enzymatic activity. (hashem2021hematopoieticcelltransplantation pages 1-2, wouters2024humanada2deficiency pages 3-4)

2.2 Risk factors

  • Genetic risk factor (causal): autosomal recessive inheritance with homozygous/compound heterozygous ADA2 pathogenic variants. (dzhus2023anarrativereview pages 1-2, wouters2024humanada2deficiency pages 1-3)
  • Consanguinity: prominent in some regional cohorts; e.g., 91% consanguineous parents in an Iranian case series. (ashari2023acaseseries pages 1-2)

Environmental risk factors: none established from retrieved sources.

2.3 Protective factors

Not established in retrieved sources.

2.4 Gene–environment interactions

Not established in retrieved sources.

3. Phenotypes

3.1 Phenotype spectrum and domains

A large NIH cohort proposes three overlapping phenotype “domains”: inflammatory/vascular, immune dysregulatory, and hematologic, with frequent overlap and phenotypic evolution over time. (barron2022thespectrumof pages 1-2)

3.2 High-value phenotype frequencies and characteristics (with HPO suggestions)

Selected quantitative phenotype frequencies are summarized in Artifact-01; key findings include:

Cutaneous/vascular

  • Skin involvement reported in 52/58 (90%); livedo racemosa 43/58 (74%) in the NIH cohort. (barron2022thespectrumof pages 3-4)
  • Brazilian cohort: mucocutaneous involvement 17/18 (94%), livedo reticularis 11/18 (62%). (melo2023abraziliannationwide pages 4-6)
  • Iranian cohort: livedo racemosa/reticularis in 11/11 (100%). (ashari2023acaseseries pages 1-2)

HPO terms (examples): livedo reticularis/livedo racemosa; Raynaud phenomenon; skin ulcer. (barron2022thespectrumof pages 3-4, barron2022thespectrumof pages 8-10)

Neurologic

  • NIH cohort: stroke in 25/58 (43%), including ischemic strokes 24/58 (41%) and hemorrhagic strokes 7/58 (12%); mean age at first stroke 5.7 years (range 0.4–20). (barron2022thespectrumof pages 3-4)
  • Meta-review: 50.3% had ≥1 neurological event; among those with neurologic manifestations, 77.5% had ≥1 cerebrovascular accident; 35.9% had multiple strokes; ischemic stroke predilection for brainstem 37.3% and deep gray matter 41.6%. (dzhus2023anarrativereview pages 1-2)

HPO terms (examples): ischemic stroke; intracranial hemorrhage; lacunar infarct; seizures. (dzhus2023anarrativereview pages 1-2, barron2022thespectrumof pages 3-4)

Hematologic

  • NIH cohort: cytopenia 28/58 (48%), pancytopenia 6/58 (10%), immune-mediated neutropenia 9/58 (16%), severe anemia 7/58 (12%), thrombocytopenia 5/58 (9%). (barron2022thespectrumof pages 4-7)

HPO terms (examples): pancytopenia; pure red cell aplasia; neutropenia; thrombocytopenia; bone marrow failure.

Immunologic

  • NIH cohort: abnormal quantitative immunoglobulins 38/58 (66%) with low IgG 55%, low IgM 62%, low IgA 43%; low class-switched memory B cells 32/47 (68%); inadequate specific antibody responses 16/39 (41%). (barron2022thespectrumof pages 3-4, barron2022thespectrumof pages 8-10)

HPO terms (examples): hypogammaglobulinemia; decreased IgG/IgM/IgA; abnormal vaccine response.

Visceral/end-organ vasculitis

  • NIH cohort: hepatomegaly 29/58 (50%), splenomegaly 31/58 (53%), portal hypertension 7/58 (12%), renal cortical lesions 13/58 (22%). (barron2022thespectrumof pages 3-4)
  • Brazilian cohort: GI involvement 8/18 (45%) including abdominal pain 8/18 (45%) and colitis/GI ulcers 2/18 (12%). (melo2023abraziliannationwide pages 4-6)

Quality-of-life impact: NIH cohort noted severe sequelae after hemorrhagic strokes and moderate neuropsychological deficiencies on testing among evaluated patients; Brazilian cohort reports chronic sequelae/disabilities in 9/18 (50%). (barron2022thespectrumof pages 4-7, melo2023abraziliannationwide pages 4-6)

4. Genetic / molecular information

4.1 Causal gene(s)

  • ADA2 (formerly CECR1). (hashem2021hematopoieticcelltransplantation pages 1-2, wouters2024humanada2deficiency pages 3-4)

4.2 Pathogenic variants

  • Variants span multiple protein domains; most are missense, but splice/intronic and structural variants can occur and may require extended testing beyond standard exon sequencing. (wouters2024humanada2deficiency pages 3-4)
  • Regional recurrence examples: Iranian cohort predominantly carried G47R (with one G321E case). (ashari2023acaseseries pages 1-2)

ClinVar/gnomAD allele frequencies: not extracted in retrieved sources.

4.3 Modifier genes, epigenetics, chromosomal abnormalities

Not established in retrieved sources.

5. Environmental information

Non-genetic environmental contributors were not identified in retrieved sources.

6. Mechanism / pathophysiology

6.1 Current mechanistic concepts (upstream→downstream causal chain)

A convergent model supported by recent reviews and primary research is: 1) Biallelic ADA2 loss-of-function → ADA2 deficiency (low/absent activity). (wouters2024humanada2deficiency pages 3-4, hashem2021hematopoieticcelltransplantation pages 1-2) 2) Myeloid skewing and inflammatory activation (monocytes/macrophages; M1 polarization) with cytokine outputs including TNF, along with reported type I/II interferon-stimulated gene signatures. (wouters2024humanada2deficiency pages 3-4, dzhus2023anarrativereview pages 1-2, barron2022thespectrumof pages 1-2) 3) Endothelial instability / impaired vascular integrity with perivascular inflammation → small/medium vessel disease, stenosis/aneurysm/occlusion → ischemia/infarction/hemorrhage (stroke; peripheral and visceral vasculopathy). (dzhus2023anarrativereview pages 1-2, wouters2024humanada2deficiency pages 3-4) 4) In parallel, hematopoietic defects (cytopenias; marrow failure) and immune dysfunction (hypogammaglobulinemia; low memory B cells; variable infection susceptibility). (barron2022thespectrumof pages 3-4, barron2022thespectrumof pages 1-2)

6.2 2024 mechanistic development: lysosomal ADA2, DNA editing, TLR9 sensing

A key 2024 Cell Reports study reports a major shift in ADA2 functional understanding, including the abstract statement: - “ADA2 localizes within the lysosomes…” and “ADA2 interacts with DNA molecules… converting deoxyadenosine (dA) to deoxyinosine (dI)…” and “…ADA2 regulate lysosomal immune sensing… by modulating TLR9 activation.” (greinertollersrud2024ada2isa pages 1-3)

This supports a cell-intrinsic innate immune mechanism linked to nucleic-acid sensing, potentially explaining interferon/TNF pathway activation beyond a purely extracellular adenosine model. (greinertollersrud2024ada2isa pages 1-3, wouters2024humanada2deficiency pages 4-5)

6.3 Model organism mechanistic evidence (2024 priority)

A 2024 zebrafish model study establishes cecr1b (ADA2-ortholog) loss-of-function with mechanistic resolution: - “Loss of Cecr1b disrupts hematopoietic stem cell specification… caused by induced inflammation in the vascular endothelium.” (brix2024ada2regulatesinflammation pages 1-2) - Rescue is shown by “blocking inflammation… modulation of the A2r pathway, or… recombinant human ADA2.” (brix2024ada2regulatesinflammation pages 1-2)

6.4 Implicated pathways (ontology suggestions)

  • GO Biological Process (suggestions): inflammatory response; regulation of tumor necrosis factor production; type I interferon signaling pathway; response to interferon-gamma; regulation of endothelial cell integrity; hematopoietic stem cell differentiation; Toll-like receptor 9 signaling pathway.
  • Cell Ontology (CL) (suggestions): monocyte; macrophage; neutrophil; endothelial cell; hematopoietic stem and progenitor cell; microglia (noted high expression of ADA2). (greinertollersrud2024ada2isa pages 1-3)
  • CHEBI (suggestions): adenosine; inosine; deoxyadenosine; deoxyinosine. (greinertollersrud2024ada2isa pages 1-3, brix2024ada2regulatesinflammation pages 1-2)

7. Anatomical structures affected

7.1 Organ/system level

  • Skin: livedo racemosa/reticularis, ulcers, necrosis. (barron2022thespectrumof pages 3-4, melo2023abraziliannationwide pages 4-6)
  • Central nervous system: lacunar ischemic strokes and hemorrhagic strokes with predilection for brainstem and deep gray matter. (dzhus2023anarrativereview pages 1-2, barron2022thespectrumof pages 4-7)
  • Hematopoietic system: bone marrow failure/cytopenias. (barron2022thespectrumof pages 4-7, hashem2021hematopoieticcelltransplantation pages 1-2)
  • Liver/spleen: hepatomegaly, splenomegaly, portal hypertension. (barron2022thespectrumof pages 3-4, wouters2024humanada2deficiency pages 1-3)
  • Kidney: renal cortical lesions. (barron2022thespectrumof pages 3-4)
  • GI tract: abdominal pain, colitis/ulcers, and severe vasculitic intestinal injury in some cases. (melo2023abraziliannationwide pages 4-6, dzhus2023anarrativereview pages 1-2)

7.2 Tissue and cell level (CL suggestions)

Key implicated cells: myeloid lineage cells (monocytes/macrophages), neutrophils, and endothelial cells; zebrafish work links vascular endothelium inflammation to impaired hematopoietic stem cell emergence. (brix2024ada2regulatesinflammation pages 1-2, dzhus2023anarrativereview pages 1-2)

7.3 Subcellular level

Recent work places physiologically relevant ADA2 activity in the lysosome and implicates lysosomal nucleic-acid sensing via TLR9. (greinertollersrud2024ada2isa pages 1-3)

8. Temporal development

8.1 Onset

Typical onset is childhood: average onset 5–7 years; ~25% before age 1 and ~77% by age 10 in a 628-patient review, though adult-onset exists. (dzhus2023anarrativereview pages 1-2)

8.2 Progression/course

Course can be relapsing or progressive with recurrent ischemic events and evolving phenotype domains over time; NIH cohort emphasizes that phenotypes can evolve and overlap. (barron2022thespectrumof pages 1-2)

9. Inheritance and population

9.1 Inheritance

Autosomal recessive (biallelic loss-of-function variants). (dzhus2023anarrativereview pages 1-2, wouters2024humanada2deficiency pages 1-3)

9.2 Epidemiology

  • Estimated carrier frequency ~1:236 and prevalence ~1:222,000 from modeling of residual ADA2 activity in vitro. (wouters2024humanada2deficiency pages 1-3)

9.3 Demographics (from literature review)

In a 628-patient review: among patients with known sex, ~46% female and 54% male; among reported ethnicities, ~50% Caucasian with representation from South Asia and the Middle East among others. (dzhus2023anarrativereview pages 1-2)

9.4 Founder effects / recurrent variants

Robust founder-effect mapping was not available in retrieved sources; however, regional recurrent variants were reported (e.g., G47R predominance in an Iranian series). (ashari2023acaseseries pages 1-2)

10. Diagnostics

10.1 Core diagnostic tests

A 2024 review states: “Identification of biallelic known pathogenic variants in ADA2… together with determination of severely diminished or absent ADA2 enzyme activity in the serum or plasma, is diagnostic.” (wouters2024humanada2deficiency pages 3-4)

10.2 ADA2 enzyme activity assays

Both HPLC and spectrophotometric assays are available for ADA2 activity measurement. (wouters2024humanada2deficiency pages 3-4)

10.3 Genetic testing approach

  • Confirm biallelic ADA2 variants (single-gene testing, panels, or exome/genome approaches). (hashem2021hematopoieticcelltransplantation pages 1-2, wouters2024humanada2deficiency pages 3-4)
  • Consider additional strategies for splice/intronic/structural variants when standard testing is inconclusive. (wouters2024humanada2deficiency pages 3-4)

10.4 Differential diagnosis

A recurring clinical issue is misdiagnosis as polyarteritis nodosa (PAN); DADA2 can constitute a significant fraction of pediatric early-onset PAN presentations in some series (as discussed in review context). (dzhus2023anarrativereview pages 1-2)

11. Outcome / prognosis

11.1 Mortality and severe outcomes

  • Overall mortality estimated ~8%, mainly in childhood, in the 628-patient review. (dzhus2023anarrativereview pages 1-2)
  • Brazilian cohort mortality 2/18 (12%). (melo2023abraziliannationwide pages 4-6)
  • Major morbidity includes recurrent strokes (often multiple), hemorrhagic stroke sequelae, amputations for severe peripheral vascular disease, and neurocognitive deficits in subsets. (barron2022thespectrumof pages 4-7, barron2022thespectrumof pages 8-10)

11.2 Prognostic factors

Not fully resolved in retrieved sources; however, genotype–phenotype relationships have been proposed (absent activity variants correlating with marrow failure/PRCA vs residual activity correlating with vascular phenotypes). (wouters2024humanada2deficiency pages 3-4)

12. Treatment

12.1 Pharmacotherapy — TNF inhibition (real-world implementation)

Anti-TNF therapy is consistently supported as first-line disease-modifying therapy for the vasculitic/ischemic phenotype.

Quantitative outcomes (multicenter): In 31 genetically confirmed patients, anti-TNF reduced median CNS/non-CNS ischemic event rate from 2.37 per 100 patient-months pre-treatment to 0.00 per 100 patient-months post-treatment (p<0.0001) and reduced PVAS from 20/63 to 2/63. (cooray2021antitumournecrosisfactor pages 1-4)

Quantitative outcomes (NIH cohort): no strokes observed during 2026 patient-months on TNF inhibitors. (barron2022thespectrumof pages 1-2)

Limitations: Anti-TNF is generally not effective for severe immunodeficiency or bone marrow failure, which may require transplantation. (cooray2021antitumournecrosisfactor pages 1-4, wouters2024humanada2deficiency pages 3-4)

MAXO suggestions (best-effort): tumor necrosis factor inhibitor therapy; immunosuppressive therapy; biologic anti-inflammatory therapy.

12.2 Curative therapy — allogeneic hematopoietic cell transplantation (HCT/HSCT)

A multinational retrospective cohort (30 patients, 38 HCTs) reports strong outcomes: - 2-year overall survival 97% and 2-year GvHD-free relapse-free survival 73%; normalization of ADA2 activity in 16/17 tested; “no new vascular events”; and resolution of hematologic and immunologic phenotypes. (hashem2021hematopoieticcelltransplantation pages 1-2)

Indications: bone marrow failure, immune cytopenia, malignancy, or immunodeficiency. (hashem2021hematopoieticcelltransplantation pages 1-2)

MAXO suggestions: hematopoietic cell transplantation; bone marrow transplantation.

12.3 Emerging/experimental approaches

  • Gene therapy/gene editing is discussed as a future curative direction in the literature base but was not captured here as a DADA2-specific human clinical trial in the available ClinicalTrials.gov search results. (cooray2021antitumournecrosisfactor pages 8-11)

13. Prevention

No primary prevention strategies exist for monogenic DADA2 beyond reproductive options; preventive care focuses on secondary/tertiary prevention of strokes and vasculitic complications using TNF inhibition and careful avoidance of contraindicated antiplatelet/anticoagulant regimens in patients at risk for hemorrhagic strokes (as emphasized in review discussion). (wouters2024humanada2deficiency pages 1-3)

14. Other species / natural disease

No naturally occurring veterinary DADA2 analog was identified in retrieved sources.

15. Model organisms

15.1 Key models and why they matter

  • Rodents: ADA2 ortholog absent (“present in all mammals except rodents”), limiting classical mouse modeling. (greinertollersrud2024ada2isa pages 1-3, hashem2017deficiencyofadenosine pages 1-2)
  • Zebrafish (2024): cecr1b loss-of-function recapitulates vascular and hematopoietic phenotypes; rescues with recombinant human ADA2 and adenosine receptor pathway modulation. (brix2024ada2regulatesinflammation pages 1-2, brix2024ada2regulatesinflammation pages 7-10)
  • Porcine tissue: porcine brain ADA2 used for glycan profiling supporting lysosomal targeting. (greinertollersrud2024ada2isa pages 1-3)

15.2 Applications and limitations

Zebrafish enable mechanistic dissection of endothelial inflammation and HSPC emergence defects and provide a platform for testing ADA2 replacement and purinergic pathway modulators; translation to human disease requires validation in patient-derived cells and clinical cohorts given species differences and the complex immune phenotype. (brix2024ada2regulatesinflammation pages 1-2, brix2024ada2regulatesinflammation pages 7-10)

Notes on citation granularity (PMID requirement)

The retrieved full texts in this run primarily provided DOIs and did not include PubMed IDs for most papers, except where OpenTargets lists PMIDs (e.g., 24552284/24552285 as discovery-era links). (OpenTargets Search: Deficiency of adenosine deaminase 2,DADA2-ADA2,CECR1) For a production-grade knowledge base entry, each cited DOI should be cross-walked to PMID in PubMed and recorded. This is a curation step rather than a scientific uncertainty.

URLs and publication dates (selected key sources)

  • Wouters et al. 2024-07-06 (online): Human ADA2 Deficiency: Ten Years Later. Current Allergy and Asthma Reports. https://doi.org/10.1007/s11882-024-01163-9 (wouters2024humanada2deficiency pages 1-3)
  • Dzhus et al. 2023-08-07 (online): A Narrative Review of the Neurological Manifestations of Human ADA2 Deficiency. Journal of Clinical Immunology. https://doi.org/10.1007/s10875-023-01555-y (dzhus2023anarrativereview pages 1-2)
  • Barron et al. 2022-01-10: The Spectrum of DADA2: 60 Patient Cohort. Frontiers in Immunology. https://doi.org/10.3389/fimmu.2021.811473 (barron2022thespectrumof pages 1-2)
  • Cooray et al. 2021: Anti-TNF treatment… prevention of ischaemic events… Rheumatology. https://doi.org/10.1093/rheumatology/keaa837 (cooray2021antitumournecrosisfactor pages 1-4)
  • Hashem et al. 2021-07-29 (online): HCT cures DADA2: report on 30 patients. Journal of Clinical Immunology. https://doi.org/10.1007/s10875-021-01098-0 (hashem2021hematopoieticcelltransplantation pages 1-2)
  • Greiner‑Tollersrud et al. 2024-11-26: ADA2 is a lysosomal deoxyadenosine deaminase… regulating TLR9. Cell Reports. https://doi.org/10.1016/j.celrep.2024.114899 (greinertollersrud2024ada2isa pages 1-3)
  • Brix et al. 2024-05: ADA2 regulates inflammation and HSC emergence via A2bR pathway in zebrafish. Communications Biology. https://doi.org/10.1038/s42003-024-06286-3 (brix2024ada2regulatesinflammation pages 1-2)

References

  1. (dzhus2023anarrativereview pages 1-2): Mariia Dzhus, Lisa Ehlers, Marjon Wouters, Katrien Jansen, Rik Schrijvers, Lien De Somer, Steven Vanderschueren, Marco Baggio, Leen Moens, Benjamin Verhaaren, Rik Lories, Giorgia Bucciol, and Isabelle Meyts. A narrative review of the neurological manifestations of human adenosine deaminase 2 deficiency. Journal of Clinical Immunology, 43:1916-1926, Aug 2023. URL: https://doi.org/10.1007/s10875-023-01555-y, doi:10.1007/s10875-023-01555-y. This article has 26 citations and is from a domain leading peer-reviewed journal.

  2. (wouters2024humanada2deficiency pages 1-3): Marjon Wouters, Lisa Ehlers, Mariia Dzhus, Verena Kienapfel, Giorgia Bucciol, Selket Delafontaine, Anneleen Hombrouck, Bethany Pillay, Leen Moens, and Isabelle Meyts. Human ada2 deficiency: ten years later. Current Allergy and Asthma Reports, 24:477-484, Jul 2024. URL: https://doi.org/10.1007/s11882-024-01163-9, doi:10.1007/s11882-024-01163-9. This article has 17 citations and is from a peer-reviewed journal.

  3. (hashem2021hematopoieticcelltransplantation pages 1-2): Hasan Hashem, Giorgia Bucciol, Seza Ozen, Sule Unal, Ikbal Ok Bozkaya, Nurten Akarsu, Mervi Taskinen, Minna Koskenvuo, Janna Saarela, Dimana Dimitrova, Dennis D. Hickstein, Amy P. Hsu, Steven M. Holland, Robert Krance, Ghadir Sasa, Ashish R. Kumar, Ingo Müller, Monica Abreu de Sousa, Selket Delafontaine, Leen Moens, Florian Babor, Federica Barzaghi, Maria Pia Cicalese, Robbert Bredius, Joris van Montfrans, Valentina Baretta, Simone Cesaro, Polina Stepensky, Neven Benedicte, Despina Moshous, Guillaume Le Guenno, David Boutboul, Jignesh Dalal, Joel P. Brooks, Elif Dokmeci, Jasmeen Dara, Carrie L. Lucas, Sophie Hambleton, Keith Wilson, Stephen Jolles, Yener Koc, Tayfun Güngör, Caroline Schnider, Fabio Candotti, Sandra Steinmann, Ansgar Schulz, Chip Chambers, Michael Hershfield, Amanda Ombrello, Jennifer A. Kanakry, and Isabelle Meyts. Hematopoietic cell transplantation cures adenosine deaminase 2 deficiency: report on 30 patients. Journal of Clinical Immunology, 41:1633-1647, Jul 2021. URL: https://doi.org/10.1007/s10875-021-01098-0, doi:10.1007/s10875-021-01098-0. This article has 89 citations and is from a domain leading peer-reviewed journal.

  4. (cooray2021antitumournecrosisfactor pages 1-4): Samantha Cooray, Ebun Omyinmi, Ying Hong, Charalampia Papadopoulou, Lorraine Harper, Eslam Al-Abadi, Ruchika Goel, Shirish Dubey, Mark Wood, Stephen Jolles, Stefan Berg, Maria Ekelund, Kate Armon, Despina Eleftheriou, and Paul A Brogan. Anti-tumour necrosis factor treatment for the prevention of ischaemic events in patients with deficiency of adenosine deaminase 2 (dada2). Rheumatology, 60:4373-4378, Jan 2021. URL: https://doi.org/10.1093/rheumatology/keaa837, doi:10.1093/rheumatology/keaa837. This article has 74 citations and is from a peer-reviewed journal.

  5. (greinertollersrud2024ada2isa pages 1-3): Ole Kristian Greiner-Tollersrud, Máté Krausz, Vincent Boehler, Aikaterini Polyzou, Maximilian Seidl, Ambra Spahiu, Zeinab Abdullah, Katarzyna Andryka-Cegielski, Felix Immunuel Dominick, Katrin Huebscher, Andreas Goschin, Cristian R. Smulski, Eirini Trompouki, Regina Link, Hilmar Ebersbach, Honnappa Srinivas, Martine Marchant, Georgios Sogkas, Dieter Staab, Cathrine Vågbø, Danilo Guerini, Sebastian Baasch, Eicke Latz, Gunther Hartmann, Philippe Henneke, Roger Geiger, Xiao P. Peng, Bodo Grimbacher, Eva Bartok, Ingrun Alseth, Max Warncke, and Michele Proietti. Ada2 is a lysosomal deoxyadenosine deaminase acting on dna involved in regulating tlr9-mediated immune sensing of dna. Cell Reports, 43:114899, Nov 2024. URL: https://doi.org/10.1016/j.celrep.2024.114899, doi:10.1016/j.celrep.2024.114899. This article has 20 citations and is from a highest quality peer-reviewed journal.

  6. (barron2022thespectrumof pages 3-4): Karyl S. Barron, Ivona Aksentijevich, Natalie T. Deuitch, Deborah L. Stone, Patrycja Hoffmann, Ryan Videgar-Laird, Ariane Soldatos, Jenna Bergerson, Camilo Toro, Cornelia Cudrici, Michele Nehrebecky, Tina Romeo, Anne Jones, Manfred Boehm, Jennifer A. Kanakry, Dimana Dimitrova, Katherine R. Calvo, Hawwa Alao, Devika Kapuria, Gil Ben-Yakov, Dominique C. Pichard, Londa Hathaway, Alessandra Brofferio, Elisa McRae, Natalia Sampaio Moura, Oskar Schnappauf, Sofia Rosenzweig, Theo Heller, Edward W. Cowen, Daniel L. Kastner, and Amanda K. Ombrello. The spectrum of the deficiency of adenosine deaminase 2: an observational analysis of a 60 patient cohort. Frontiers in Immunology, Jan 2022. URL: https://doi.org/10.3389/fimmu.2021.811473, doi:10.3389/fimmu.2021.811473. This article has 96 citations and is from a peer-reviewed journal.

  7. (barron2022thespectrumof pages 4-7): Karyl S. Barron, Ivona Aksentijevich, Natalie T. Deuitch, Deborah L. Stone, Patrycja Hoffmann, Ryan Videgar-Laird, Ariane Soldatos, Jenna Bergerson, Camilo Toro, Cornelia Cudrici, Michele Nehrebecky, Tina Romeo, Anne Jones, Manfred Boehm, Jennifer A. Kanakry, Dimana Dimitrova, Katherine R. Calvo, Hawwa Alao, Devika Kapuria, Gil Ben-Yakov, Dominique C. Pichard, Londa Hathaway, Alessandra Brofferio, Elisa McRae, Natalia Sampaio Moura, Oskar Schnappauf, Sofia Rosenzweig, Theo Heller, Edward W. Cowen, Daniel L. Kastner, and Amanda K. Ombrello. The spectrum of the deficiency of adenosine deaminase 2: an observational analysis of a 60 patient cohort. Frontiers in Immunology, Jan 2022. URL: https://doi.org/10.3389/fimmu.2021.811473, doi:10.3389/fimmu.2021.811473. This article has 96 citations and is from a peer-reviewed journal.

  8. (melo2023abraziliannationwide pages 4-6): Adriana Melo, Luciana Martins de Carvalho, Virginia Paes Leme Ferriani, André Cavalcanti, Simone Appenzeller, Valéria Rossato Oliveira, Herberto Chong Neto, Nelson Augusto Rosário, Fabiano de Oliveira Poswar, Matheus Xavier Guimaraes, Cristina Maria Kokron, Rayana Elias Maia, Guilherme Diogo Silva, Gabriel Keller, Mauricio Domingues Ferreira, Dewton Moraes Vasconcelos, Myrthes Anna Maragna Toledo-Barros, Samar Freschi Barros, Nilton Salles Rosa Neto, Marta Helena Krieger, Jorge Kalil, and Leonardo Oliveira Mendonça. A brazilian nationwide multicenter study on deficiency of deaminase-2 (dada2). Advances in Rheumatology, 63:1-9, May 2023. URL: https://doi.org/10.1186/s42358-023-00303-5, doi:10.1186/s42358-023-00303-5. This article has 3 citations.

  9. (ashari2023acaseseries pages 1-2): Kosar Asna Ashari, Nahid Aslani, Nima Parvaneh, Raheleh Assari, Morteza Heidari, Mohammadreza Fathi, Fatemeh Tahghighi Sharabian, Alireza Ronagh, Mohammad Shahrooei, Alireza Moafi, Nima Rezaei, and Vahid Ziaee. A case series of ten plus one deficiency of adenosine deaminase 2 (dada2) patients in iran. Pediatric Rheumatology Online Journal, Jun 2023. URL: https://doi.org/10.1186/s12969-023-00838-3, doi:10.1186/s12969-023-00838-3. This article has 7 citations.

  10. (barron2022thespectrumof pages 8-10): Karyl S. Barron, Ivona Aksentijevich, Natalie T. Deuitch, Deborah L. Stone, Patrycja Hoffmann, Ryan Videgar-Laird, Ariane Soldatos, Jenna Bergerson, Camilo Toro, Cornelia Cudrici, Michele Nehrebecky, Tina Romeo, Anne Jones, Manfred Boehm, Jennifer A. Kanakry, Dimana Dimitrova, Katherine R. Calvo, Hawwa Alao, Devika Kapuria, Gil Ben-Yakov, Dominique C. Pichard, Londa Hathaway, Alessandra Brofferio, Elisa McRae, Natalia Sampaio Moura, Oskar Schnappauf, Sofia Rosenzweig, Theo Heller, Edward W. Cowen, Daniel L. Kastner, and Amanda K. Ombrello. The spectrum of the deficiency of adenosine deaminase 2: an observational analysis of a 60 patient cohort. Frontiers in Immunology, Jan 2022. URL: https://doi.org/10.3389/fimmu.2021.811473, doi:10.3389/fimmu.2021.811473. This article has 96 citations and is from a peer-reviewed journal.

  11. (barron2022thespectrumof pages 1-2): Karyl S. Barron, Ivona Aksentijevich, Natalie T. Deuitch, Deborah L. Stone, Patrycja Hoffmann, Ryan Videgar-Laird, Ariane Soldatos, Jenna Bergerson, Camilo Toro, Cornelia Cudrici, Michele Nehrebecky, Tina Romeo, Anne Jones, Manfred Boehm, Jennifer A. Kanakry, Dimana Dimitrova, Katherine R. Calvo, Hawwa Alao, Devika Kapuria, Gil Ben-Yakov, Dominique C. Pichard, Londa Hathaway, Alessandra Brofferio, Elisa McRae, Natalia Sampaio Moura, Oskar Schnappauf, Sofia Rosenzweig, Theo Heller, Edward W. Cowen, Daniel L. Kastner, and Amanda K. Ombrello. The spectrum of the deficiency of adenosine deaminase 2: an observational analysis of a 60 patient cohort. Frontiers in Immunology, Jan 2022. URL: https://doi.org/10.3389/fimmu.2021.811473, doi:10.3389/fimmu.2021.811473. This article has 96 citations and is from a peer-reviewed journal.

  12. (OpenTargets Search: Deficiency of adenosine deaminase 2,DADA2-ADA2,CECR1): Open Targets Query (Deficiency of adenosine deaminase 2,DADA2-ADA2,CECR1, 2 results). Buniello, A. et al. (2025). Open Targets Platform: facilitating therapeutic hypotheses building in drug discovery. Nucleic Acids Research.

  13. (melo2023abraziliannationwide pages 1-2): Adriana Melo, Luciana Martins de Carvalho, Virginia Paes Leme Ferriani, André Cavalcanti, Simone Appenzeller, Valéria Rossato Oliveira, Herberto Chong Neto, Nelson Augusto Rosário, Fabiano de Oliveira Poswar, Matheus Xavier Guimaraes, Cristina Maria Kokron, Rayana Elias Maia, Guilherme Diogo Silva, Gabriel Keller, Mauricio Domingues Ferreira, Dewton Moraes Vasconcelos, Myrthes Anna Maragna Toledo-Barros, Samar Freschi Barros, Nilton Salles Rosa Neto, Marta Helena Krieger, Jorge Kalil, and Leonardo Oliveira Mendonça. A brazilian nationwide multicenter study on deficiency of deaminase-2 (dada2). Advances in Rheumatology, 63:1-9, May 2023. URL: https://doi.org/10.1186/s42358-023-00303-5, doi:10.1186/s42358-023-00303-5. This article has 3 citations.

  14. (brix2024ada2regulatesinflammation pages 1-2): Alessia Brix, Laura Belleri, Alex Pezzotta, Emanuela Pettinato, Mara Mazzola, Matteo Zoccolillo, Anna Marozzi, Rui Monteiro, Filippo Del Bene, Alessandra Mortellaro, and Anna Pistocchi. Ada2 regulates inflammation and hematopoietic stem cell emergence via the a2br pathway in zebrafish. Communications Biology, May 2024. URL: https://doi.org/10.1038/s42003-024-06286-3, doi:10.1038/s42003-024-06286-3. This article has 10 citations and is from a peer-reviewed journal.

  15. (wouters2024humanada2deficiency pages 3-4): Marjon Wouters, Lisa Ehlers, Mariia Dzhus, Verena Kienapfel, Giorgia Bucciol, Selket Delafontaine, Anneleen Hombrouck, Bethany Pillay, Leen Moens, and Isabelle Meyts. Human ada2 deficiency: ten years later. Current Allergy and Asthma Reports, 24:477-484, Jul 2024. URL: https://doi.org/10.1007/s11882-024-01163-9, doi:10.1007/s11882-024-01163-9. This article has 17 citations and is from a peer-reviewed journal.

  16. (wouters2024humanada2deficiency pages 4-5): Marjon Wouters, Lisa Ehlers, Mariia Dzhus, Verena Kienapfel, Giorgia Bucciol, Selket Delafontaine, Anneleen Hombrouck, Bethany Pillay, Leen Moens, and Isabelle Meyts. Human ada2 deficiency: ten years later. Current Allergy and Asthma Reports, 24:477-484, Jul 2024. URL: https://doi.org/10.1007/s11882-024-01163-9, doi:10.1007/s11882-024-01163-9. This article has 17 citations and is from a peer-reviewed journal.

  17. (cooray2021antitumournecrosisfactor pages 8-11): Samantha Cooray, Ebun Omyinmi, Ying Hong, Charalampia Papadopoulou, Lorraine Harper, Eslam Al-Abadi, Ruchika Goel, Shirish Dubey, Mark Wood, Stephen Jolles, Stefan Berg, Maria Ekelund, Kate Armon, Despina Eleftheriou, and Paul A Brogan. Anti-tumour necrosis factor treatment for the prevention of ischaemic events in patients with deficiency of adenosine deaminase 2 (dada2). Rheumatology, 60:4373-4378, Jan 2021. URL: https://doi.org/10.1093/rheumatology/keaa837, doi:10.1093/rheumatology/keaa837. This article has 74 citations and is from a peer-reviewed journal.

  18. (hashem2017deficiencyofadenosine pages 1-2): Hasan Hashem, Susan J Kelly, Nancy J Ganson, and Michael S Hershfield. Deficiency of adenosine deaminase 2 (dada2), an inherited cause of polyarteritis nodosa and a mimic of other systemic rheumatologic disorders. Current Rheumatology Reports, 19:1-9, Oct 2017. URL: https://doi.org/10.1007/s11926-017-0699-8, doi:10.1007/s11926-017-0699-8. This article has 84 citations and is from a peer-reviewed journal.

  19. (brix2024ada2regulatesinflammation pages 7-10): Alessia Brix, Laura Belleri, Alex Pezzotta, Emanuela Pettinato, Mara Mazzola, Matteo Zoccolillo, Anna Marozzi, Rui Monteiro, Filippo Del Bene, Alessandra Mortellaro, and Anna Pistocchi. Ada2 regulates inflammation and hematopoietic stem cell emergence via the a2br pathway in zebrafish. Communications Biology, May 2024. URL: https://doi.org/10.1038/s42003-024-06286-3, doi:10.1038/s42003-024-06286-3. This article has 10 citations and is from a peer-reviewed journal.

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