Immunodeficiency 57

Mendelian MONDO:0020849 Pathograph 16 Show in embeddings browser inborn error of immunity autosomal recessive disease rare disease

Immunodeficiency 57 with autoinflammation (IMD57) is the autosomal recessive disease caused by biallelic loss-of-function variants in RIPK1, and it is unusual in combining immunodeficiency with autoinflammation in the same patient. RIPK1 sits immediately downstream of TNFR1 in signalling complex I, where it does two different jobs: as a scaffold it supports the ubiquitination events that route the signal into NF-kappaB and MAPK activation and so keep the cell alive, and as a kinase it can instead drive the cell into apoptosis or, when caspase-8 is unavailable, necroptosis. Losing the protein therefore removes a pro-survival signal and a cell-death brake at once. The consequences are correspondingly two-sided: reduced NF-kappaB activity with defective T- and B-cell differentiation and impaired cytokine secretion on one side, and increased inflammasome activity with cells prone to necroptosis on the other. Patients present in the first year of life with recurrent bacterial, viral and fungal infections, early-onset inflammatory bowel disease, progressive polyarthritis and lymphopenia. Only a few families have been reported. Haematopoietic stem cell transplantation corrected the cytokine production defect and resolved the clinical picture in one reported patient, which is the strongest evidence that the disease is driven by the haematopoietic compartment.

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1
Mappings
1
Inheritance
6
Pathophys.
14
Phenotypes
4
Gaps
16
Pathograph
1
Genes
8
Medical Actions
4
References
1
Deep Research
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Mappings

MONDO
MONDO:0020849 immunodeficiency 57
skos:exactMatch MONDO
👪

Inheritance

1
Autosomal recessive inheritance HP:0000007
IMD57 requires two defective RIPK1 alleles. Reported patients have been homozygous, several from consanguineous families. Heterozygous carriers are unaffected. The distinction from the dominant disease at the same locus is not one of dosage but of consequence: cleavage-resistant RIPK1 variants at Asp324 act in the heterozygous state and cause a hyperinflammatory disease, not this one.
Autosomal recessive inheritance
Show evidence (2 references)
PMID:30026316 SUPPORT Human Clinical
"We report four patients from three unrelated families with complete RIPK1 deficiency caused by rare homozygous mutations."
The founding cohort, establishing homozygous loss of function as the genotype.
PMID:30591564 SUPPORT Human Clinical
"Here, we report on eight patients from six unrelated pedigrees with biallelic loss-of-function mutations in RIPK1 presenting with primary immunodeficiency and/or intestinal inflammation."
Independent replication in a second, larger series, with the same biallelic loss-of-function requirement.
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Discussions and Knowledge Gaps

4
Are the motor delay and intellectual disability reported in one patient part of RIPK1 deficiency, or incidental to it?
KNOWLEDGE GAP ripk1_neurodevelopmental_features
Attached to
phenotypes#Motor delay phenotypes#Mild intellectual disability
Both features come from a single case report whose authors say explicitly that they had not previously been associated with the disease. One patient is not a phenotype, and in a disorder presenting with severe infection and chronic enteropathy in the first year of life, developmental delay has several ordinary explanations that have nothing to do with RIPK1: hypoxia, malnutrition, prolonged hospitalisation, or the consanguinity that produced the homozygous variant also producing a second one. The fourteen-patient series records no neurological feature at all, which is weak evidence against but is not nothing. Nothing in this entry's pathograph reaches either phenotype and nothing should until a second patient is reported.
What produces the upper gastrointestinal, perianal and hepatosplenic features of RIPK1 deficiency, none of which the located mechanism reaches?
KNOWLEDGE GAP ripk1_extraintestinal_features
Attached to
phenotypes#Gastritis phenotypes#Esophagitis phenotypes#Perianal disease phenotypes#Hepatomegaly phenotypes#Splenomegaly
The entry's pathograph explains the disease through two arms: lost NF-kappaB and MAPK signalling producing the lymphocyte differentiation defect, and necroptosis plus inflammasome activity producing intestinal inflammation. The located mechanistic work places the cell-death defect specifically in intestinal epithelial cells. But the largest clinical series records esophagitis in four patients, gastritis in three, perianal disease in eight and hepatosplenomegaly in four, and none of those sites is intestinal epithelium. Gastritis was previously drawn as a DIRECT consequence of the intestinal epithelial node, which contradicted this rationale and was wrong for the same reason an esophagitis edge would have been: the node binds intestinal epithelial cell, and the stomach is not that cell type. That edge is removed and the phenotype sits in this gap with its siblings. Either the epithelial death defect is not confined to the intestine, or a second mechanism is operating, or some of these are complications of treatment and of the infection burden rather than of the disease. The table cannot distinguish those, and no located source addresses it, so the phenotypes are recorded with no incoming edge rather than attached to the nearest plausible node.
By what route does loss of RIPK1 increase inflammasome activity, when the same loss reduces NF-kappaB signalling?
KNOWLEDGE GAP ripk1_inflammasome_route
Attached to
pathophysiology#Increased Inflammasome Activity
This is the hinge of the disease. RIPK1 deficiency lowers one inflammatory output and raises another in the same patient, and an account of the disease that does not explain the second is incomplete. A non-canonical TLR4-TRIF-RIPK1-FADD-caspase-8 axis has been proposed in review, but no located primary source demonstrates it in RIPK1-deficient human cells, so the causal edge in this entry is typed with unknown intermediates rather than as a mechanism.
Is the progressive polyarthritis driven by the autoinflammatory arm, by the infection burden, or by both?
KNOWLEDGE GAP ripk1_arthritis_driver
Attached to
phenotypes#Arthritis
The arthritis is attached to the inflammasome node in this entry because it is the autoinflammatory feature, but no located source establishes that. A patient with recurrent infections and a chronically inflamed gut has other routes to synovitis, and distinguishing them would change whether joint disease is expected to respond to correcting the haematopoietic compartment.
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Pathophysiology

6
RIPK1 Loss of Function
Biallelic loss-of-function variants abolish RIPK1 protein. RIPK1 is a 75.9 kDa protein with an N-terminal kinase domain, a C-terminal death domain and an intermediate domain carrying a RIP homotypic interaction motif, and it is recruited with TRADD to TNFR1 to form signalling complex I. Because the protein carries both a scaffolding role and a kinase role, its complete absence removes two opposing functions simultaneously, which is why the resulting disease is not simply a loss of inflammation or a gain of it.
RIPK1 hgnc:10019 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves RIPK1 (hgnc:10019). hgnc:10019 is a gene from the HUGO Gene Nomenclature Committee.
Genetic context variant_origin: GERMLINE zygosity: HOMOZYGOUS functional_impact_category: LOSS_OF_FUNCTION
Downstream
Impaired NF-kappaB and MAPK Signalling RIPK1 is a component of complex I, whose ubiquitination provides the docking platform for the kinases that activate NF-kappaB and MAPK. Without RIPK1 that platform is not assembled.
Necroptosis Susceptibility Losing RIPK1 does not abolish cell death but redirects it. Patient cells were prone to necroptosis in vitro.
Increased Inflammasome Activity Inflammasome activity is increased rather than decreased in RIPK1-deficient patients. The route is not established: a non-canonical TLR4-TRIF-RIPK1-FADD-caspase-8 axis has been proposed, and this entry does not assert it.
Show evidence (1 reference)
PMID:34163478 SUPPORT REVIEW SYNTHESIS Other
"RIPK1 is a 75.9 kDa protein with an amino-terminal kinase domain (KD), a carboxy-terminal death domain (DD), and an intermediate domain (ID) in-between which contains a Rip homotypic interaction motif (RHIM)."
The domain architecture behind the dual scaffold/kinase role. This is the review's synthesis of established structural work, not its own result.
Impaired NF-kappaB and MAPK Signalling
Complex I normally routes the TNFR1 signal into NF-kappaB and MAPK activation, producing pro-inflammatory cytokines and promoting survival. In RIPK1-deficient cells both arms are blunted: MAPK activation and cytokine secretion are impaired. This is the immunodeficiency half of the disease.
patient-derived fibroblast CL:0000057 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves patient-derived fibroblast, annotated with fibroblast (CL:0000057). CL:0000057 is a cell type from the Cell Ontology.
canonical NF-kappaB signal transduction GO:0007249 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves decreased canonical NF-kappaB signal transduction (GO:0007249). GO:0007249 is a biological process from the Gene Ontology. ↓ DECREASED MAPK cascade GO:0000165 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves decreased MAPK cascade (GO:0000165). GO:0000165 is a biological process from the Gene Ontology. ↓ DECREASED cytokine production GO:0001816 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves decreased cytokine production (GO:0001816). GO:0001816 is a biological process from the Gene Ontology. ↓ DECREASED
Downstream
Defective T and B Cell Differentiation NF-kappaB signalling is required for lymphocyte development, and its reduction in these patients is accompanied by defective differentiation of both lineages.
Show evidence (1 reference)
PMID:30026316 SUPPORT In Vitro
"In vitro, RIPK1-deficient cells showed impaired mitogen-activated protein kinase activation and cytokine secretion and were prone to necroptosis."
Measures the MAPK and cytokine arms in patient cells.
Defective T and B Cell Differentiation
Both lymphocyte lineages differentiate abnormally, which is the cellular basis of the lymphopenia and of the susceptibility to bacterial, viral and fungal organisms alike. A defect confined to one lineage would not produce that breadth.
T cell CL:0000084 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves T cell (CL:0000084). CL:0000084 is a cell type from the Cell Ontology. B cell CL:0000236 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves B cell (CL:0000236). CL:0000236 is a cell type from the Cell Ontology.
Downstream
Lymphopenia
Recurrent infections Defective differentiation of both lymphocyte lineages leaves the patient unable to mount adequate adaptive responses, which is the immunodeficiency the patients present with.
Pneumonia Pneumonia is the commonest single infection recorded in the published cohort, in eight of fourteen patients, and it follows the lymphocyte differentiation defect by the ordinary route from immunodeficiency to lower respiratory tract infection. The intermediates are known in general terms and are not specific to this disease.
Show evidence (1 reference)
PMID:30591564 SUPPORT Human Clinical
"Mutations in RIPK1 were associated with reduced NF-κB activity, defective differentiation of T and B cells, increased inflammasome activity, and impaired response to TNFR1-mediated cell death in intestinal epithelial cells."
The differentiation defect in both lineages.
Necroptosis Susceptibility
RIPK1-deficient cells are prone to necroptosis. Necroptosis is lytic and releases intracellular contents, so a tissue whose cells die this way generates inflammation rather than being cleared quietly, which is one route by which the loss of a pro-survival signal produces an inflammatory phenotype.
necroptotic signaling pathway GO:0097527 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves increased necroptotic signaling pathway (GO:0097527). GO:0097527 is a biological process from the Gene Ontology. ↑ INCREASED
Downstream
Intestinal Epithelial Injury and Inflammation The intestinal epithelium is where the cell-death handling defect is demonstrated in these patients, and where the clinical consequence is most conspicuous. The intervening steps between the altered death response and the established colitis are not resolved in the cited work.
Increased Inflammasome Activity The necroptotic machinery is part of how the raised IL-1 beta output is produced, not merely a parallel consequence of the same lesion: blocking MLKL reduces IL-1 beta secretion in RIPK1-deficient cells, as does blocking NLRP3. That pharmacological result is what makes this an edge rather than two independent arms.
Show evidence (1 reference)
PMID:30026316 SUPPORT In Vitro
"In vitro, RIPK1-deficient cells showed impaired mitogen-activated protein kinase activation and cytokine secretion and were prone to necroptosis."
The necroptosis susceptibility, measured in patient cells.
Increased Inflammasome Activity
Inflammasome activity is raised in RIPK1-deficient patients. This is the autoinflammatory half of the disease and the reason the entry is not simply an immunodeficiency: the same lesion that blunts one inflammatory output amplifies another.
NLRP3 inflammasome complex assembly GO:0044546 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves increased NLRP3 inflammasome complex assembly (GO:0044546). GO:0044546 is a biological process from the Gene Ontology. ↑ INCREASED
Downstream
Intestinal Epithelial Injury and Inflammation
Arthritis The polyarthritis is the joint manifestation of the autoinflammatory arm. No located source traces the steps from inflammasome activation to synovitis in these patients, so the edge is recorded with its intermediates unknown rather than as a mechanism.
Show evidence (3 references)
PMID:30591564 SUPPORT Human Clinical
"Mutations in RIPK1 were associated with reduced NF-κB activity, defective differentiation of T and B cells, increased inflammasome activity, and impaired response to TNFR1-mediated cell death in intestinal epithelial cells."
The increased inflammasome activity.
PMID:34163478 SUPPORT REVIEW SYNTHESIS Other
"The inflammatory component of this disease is possibly related to the activation of NLRP3 inflammasome and high production of IL-1β cytokine"
Names the inflammasome as NLRP3 and the cytokine output as IL-1 beta, which is what the GO binding on this node records. The review states it as a possible attribution rather than a settled one, and the hedge is the review's own.
PMID:34163478 SUPPORT REVIEW SYNTHESIS Other
"In contrast, IL-1β production was markedly increased in PHA-stimulated patient’s blood"
The measurement behind the attribution: IL-1 beta rose markedly in stimulated patient blood, against a background of reduced IL-6, TNF and IL-12 in the same cells. That opposite direction is the argument for this node existing alongside the signalling-loss node rather than being folded into it.
Intestinal Epithelial Injury and Inflammation
The gut is the organ where the two arms of the disease meet. Intestinal epithelial cells respond abnormally to TNFR1-mediated death signals, and the result clinically is chronic inflammation of the digestive tract presenting in the first year of life.
intestinal epithelial cell CL:0002563 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves intestinal epithelial cell (CL:0002563). CL:0002563 is a cell type from the Cell Ontology.
Downstream
Colitis
Failure to thrive Chronic enteropathy impairs nutrient absorption and intake, and the infection burden adds to the energy deficit.
Show evidence (1 reference)
PMID:30591564 SUPPORT Human Clinical
"Mutations in RIPK1 were associated with reduced NF-κB activity, defective differentiation of T and B cells, increased inflammasome activity, and impaired response to TNFR1-mediated cell death in intestinal epithelial cells."
Locates the defective death response in the intestinal epithelium, the cell type bound on this node.
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Pathograph

Use the checkboxes to hide or show graph categories. Hover nodes for evidence and cross-linked metadata.
Pathograph: causal mechanism network for Immunodeficiency 57 Interactive directed graph showing how pathophysiology mechanisms, phenotypes, genetic factors and variants, experimental models, environmental triggers, and treatments relate through causal and linked edges.
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Phenotypes

14
Blood 1
Lymphopenia VERY_FREQUENT Decreased total lymphocyte count HP:0001888 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Lymphopenia, annotated with Decreased total lymphocyte count (HP:0001888). HP:0001888 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:30026316 SUPPORT Human Clinical
"They had immunodeficiency with lymphopenia and altered production of various cytokines revealed by whole-blood assays."
Lymphopenia in the founding cohort.
Cardiovascular 1
Splenomegaly OCCASIONAL HP:0001744 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Splenomegaly (HP:0001744). HP:0001744 is a phenotype from the Human Phenotype Ontology.
Show evidence (2 references)
PMID:34163478 SUPPORT REVIEW SYNTHESIS Other
"| family 4 | P5 | Caucasian | M | 1844T>C | I615T | 6 mos. | LLLR | Y | Y | Y | N | Y | N | N | Y | sepsis, esophagitis, gastritis, perianal disease | Ab, AZA, CS, IFX | Died |"
Table 1, patient P5: the `Spleno megaly` column reads Y.
PMID:34163478 SUPPORT REVIEW SYNTHESIS Other
"| family 11 | P14 | Chinese | M | 998C>A 1934C>T | S333* T645M | 3 mos. | HLHL | Y | Y | Y | N | Y | Y | n.r. | Y | anemia, jaundice, perianal abscess, anal fistula, malnutrition | IVIG, Ab | Died |"
Patient P14, whose row also carries anemia and jaundice in the `Others` column, which is the one row where a haematological explanation is at least suggested.
Digestive 4
Colitis VERY_FREQUENT HP:0002583 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Early-onset inflammatory bowel disease, annotated with Colitis (HP:0002583). HP:0002583 is a phenotype from the Human Phenotype Ontology.
Show evidence (2 references)
PMID:30026316 SUPPORT Human Clinical
"The patients suffered from recurrent infections, early-onset inflammatory bowel disease, and progressive polyarthritis."
The gastrointestinal presentation in the founding cohort.
PMID:30591564 SUPPORT Human Clinical
"Here, we report on eight patients from six unrelated pedigrees with biallelic loss-of-function mutations in RIPK1 presenting with primary immunodeficiency and/or intestinal inflammation."
Independent replication, and the "and/or" is the source of the note that the two presentations can occur separately.
Gastritis OCCASIONAL HP:0005263 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Gastritis (HP:0005263). HP:0005263 is a phenotype from the Human Phenotype Ontology.
Show evidence (3 references)
PMID:34163478 SUPPORT REVIEW SYNTHESIS Other
"| family 4 | P5 | Caucasian | M | 1844T>C | I615T | 6 mos. | LLLR | Y | Y | Y | N | Y | N | N | Y | sepsis, esophagitis, gastritis, perianal disease | Ab, AZA, CS, IFX | Died |"
Table 1 of the review, patient P5. The `Others` column names gastritis explicitly. Gastritis is listed for three of the fourteen patients with recessive RIPK1 deficiency in that table (P5, P8 and P13), which is the basis for the frequency band.
PMID:34163478 SUPPORT REVIEW SYNTHESIS Other
"| family 7 | P8 | Arab | F | 954delG | M318Ifs*194 | 1 day | LLLL | Y | N | N | N | N | N | N | N | esophagitis, gastritis, UTI, perianal disease | n.r. | Died |"
Patient P8, the second of the three rows naming gastritis. P8 carries a frameshift allele where P5 carries a missense one, so the finding is not confined to one variant class.
PMID:34163478 SUPPORT REVIEW SYNTHESIS Other
"| family 10 | P13 | South America | M | 636C>G | Y212* | 1 day | LLLL | Y | Y | Y | N | N | N | N | N | esophagitis, gastritis | n.r. | Alive |"
Patient P13, the third row. P13 survived where P5 and P8 did not, so gastritis is not only a feature of the fatal cases.
Esophagitis OCCASIONAL HP:0100633 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Esophagitis (HP:0100633). HP:0100633 is a phenotype from the Human Phenotype Ontology.
Show evidence (2 references)
PMID:34163478 SUPPORT REVIEW SYNTHESIS Other
"| family 8 | P9 | Arab | F | 1934C>T | T645M | 1 day | n.r. | Y | N | N | Y | Y | N | N | Y | OM, esophagitis, UTI, perianal disease | Ab, AZA, CS, IFX | Alive |"
Table 1, patient P9: esophagitis in the `Others` column.
PMID:34163478 SUPPORT REVIEW SYNTHESIS Other
"| family 10 | P13 | South America | M | 636C>G | Y212* | 1 day | LLLL | Y | Y | Y | N | N | N | N | N | esophagitis, gastritis | n.r. | Alive |"
Patient P13, who carries esophagitis and gastritis together, which is the pattern in three of the four rows.
Hepatomegaly OCCASIONAL HP:0002240 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Hepatomegaly (HP:0002240). HP:0002240 is a phenotype from the Human Phenotype Ontology.
Show evidence (2 references)
PMID:34163478 SUPPORT REVIEW SYNTHESIS Other
"| family 6 | P7 | Caucasian | F | 1278C>A | Y426* | 1 day | LLLL | Y | Y | Y | N | N | N | N | N | GI infections, U/LRI, septicemia, hepatitis | CS, HSCT | Died |"
Table 1, patient P7: the `Hepato megaly` column reads Y.
PMID:34163478 SUPPORT REVIEW SYNTHESIS Other
"| family 10 | P13 | South America | M | 636C>G | Y212* | 1 day | LLLL | Y | Y | Y | N | N | N | N | N | esophagitis, gastritis | n.r. | Alive |"
Patient P13, the second of the four. P13's row also shows the splenomegaly column reading Y, which is the co-occurrence the description records.
Head and Neck 1
Oral ulcers FREQUENT HP:0000155 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Oral lesions or ulcers, annotated with Oral ulcer (HP:0000155). HP:0000155 is a phenotype from the Human Phenotype Ontology.
Show evidence (2 references)
PMID:34163478 SUPPORT REVIEW SYNTHESIS Other
"| family 8 | P9 | Arab | F | 1934C>T | T645M | 1 day | n.r. | Y | N | N | Y | Y | N | N | Y | OM, esophagitis, UTI, perianal disease | Ab, AZA, CS, IFX | Alive |"
Table 1, patient P9: the `Oral lesion/ulcers` column reads Y.
PMID:34163478 SUPPORT REVIEW SYNTHESIS Other
"| family 9 | P10 | North Africa | M | 1802G>A | C601Y | 6 mos. | LLRL | Y | N | N | N | Y | N | N | Y | OM, perianal disease, omphalitis | Ab, AF | Alive |"
Patient P10, one of three affected siblings in family 9, all three of whom carry the finding. That clustering is why the description warns against reading the count as six independent observations.
Immune 2
Recurrent infections VERY_FREQUENT HP:0002719 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Recurrent infections (HP:0002719). HP:0002719 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:30026316 SUPPORT Human Clinical
"The patients suffered from recurrent infections, early-onset inflammatory bowel disease, and progressive polyarthritis."
Recurrent infection in all four patients of the founding cohort.
Pneumonia FREQUENT HP:0002090 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Pneumonia (HP:0002090). HP:0002090 is a phenotype from the Human Phenotype Ontology.
Show evidence (2 references)
PMID:34163478 SUPPORT REVIEW SYNTHESIS Other
"| family 2 | P3 | Arab | F | 688_688+20del | N230Hfs*14 | 1 mo. | LLLL | Y | N | N | Y | Y | N | N | N | recurrent HSV1 infection | HSCT | Died |"
Table 1, patient P3: the `Pneumonia` column reads Y. This row also shows the recurrent HSV1 infection that sits beside the bacterial burden.
PMID:34163478 SUPPORT REVIEW SYNTHESIS Other
"| family 5 | P6 | Arab | F | 1934C>T | T645M | 1 mo. | RRRH | n.r. | n.r. | n.r. | N | Y | N | N | N | OM, U/LRI, perianal disease | Ab | n.r. |"
Patient P6, whose row shows pneumonia together with otitis media and upper and lower respiratory tract infections, which is the composite the `Recurrent infections` phenotype covers.
Musculoskeletal 1
Arthritis FREQUENT HP:0001369 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Progressive polyarthritis, annotated with Arthritis (HP:0001369). HP:0001369 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:30026316 SUPPORT Human Clinical
"The patients suffered from recurrent infections, early-onset inflammatory bowel disease, and progressive polyarthritis."
Polyarthritis in the founding cohort.
Nervous System 2
Motor delay HP:0001270 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Severe motor delay, annotated with Motor delay (HP:0001270). HP:0001270 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:31213653 SUPPORT Human Clinical
"Our patient exhibited severe motor delay and mild intellectual disability, which were previously unknown."
The paper's own statement that this feature had not previously been associated with RIPK1 deficiency. The sentence names the motor and the cognitive feature separately, which is why they are curated as two phenotypes.
Mild intellectual disability HP:0001256 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Mild intellectual disability (HP:0001256). HP:0001256 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:31213653 SUPPORT Human Clinical
"Our patient exhibited severe motor delay and mild intellectual disability, which were previously unknown."
The same sentence, quoted for the cognitive half of what it reports.
Growth 1
Failure to thrive HP:0001508 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Failure to thrive (HP:0001508). HP:0001508 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:31213653 SUPPORT Human Clinical
"Here, we report a novel homozygous RIPK1 variant in a boy with immunodeficiency and chronic enteropathy."
Chronic enteropathy in a genetically confirmed patient, which is the route to the growth failure.
Other 1
Perianal disease FREQUENT
Show evidence (2 references)
PMID:34163478 SUPPORT REVIEW SYNTHESIS Other
"| family 9 | P11 | North Africa | M | 1802G>A | C601Y | 20 days | LLLL | Y | N | N | N | Y | N | N | Y | OM, tetany, perianal disease | Ab, AF | Alive |"
Table 1, patient P11: perianal disease in the `Others` column, reported as the aggregate rather than as a named lesion. This is the form seven of the eight rows take.
PMID:34163478 SUPPORT REVIEW SYNTHESIS Other
"| family 11 | P14 | Chinese | M | 998C>A 1934C>T | S333* T645M | 3 mos. | HLHL | Y | Y | Y | N | Y | Y | n.r. | Y | anemia, jaundice, perianal abscess, anal fistula, malnutrition | IVIG, Ab | Died |"
The exception: P14's lesions are itemised as perianal abscess and anal fistula. Both have HPO terms, but a single patient does not license binding the phenotype as a whole to either.
🧬

Genetic Associations

1
RIPK1
Gene: RIPK1 hgnc:10019 HUGO Gene Nomenclature Committee (hgnc) Relation: this disease-associated gene is this gene This disease-associated gene is RIPK1 (hgnc:10019). hgnc:10019 is a gene from the HUGO Gene Nomenclature Committee. relationship_type: CAUSATIVE
Show evidence (2 references)
PMID:30026316 SUPPORT Human Clinical
"RIPK1 (receptor-interacting serine/threonine kinase 1) is a master regulator of signaling pathways leading to inflammation and cell death and is of medical interest as a drug target."
Identifies the gene product and its dual role in inflammation and cell death.
PMID:34163478 SUPPORT REVIEW SYNTHESIS Other
"This review discusses the molecular pathogenesis of RIPK1-deficiency and cleavage-resistant RIPK1 induced autoinflammatory (CRIA) disorders and summarizes the clinical manifestations of respective diseases to help with the identification of new patients."
Sets the two RIPK1 diseases side by side, which is the basis for the warning in this entry's notes against conflating them.
💊

Medical Actions

8
Haematopoietic Stem Cell Transplantation
Action: haematopoietic stem cell transplantationNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is haematopoietic stem cell transplantation, annotated with Hematopoietic Cell Transplantation (NCIT:C15431). NCIT:C15431 is a clinical intervention from the NCI Thesaurus. Ontology label: Hematopoietic Cell Transplantation NCIT:C15431
Platform: Cell therapy
Transplantation reversed the cytokine production defect and resolved clinical symptoms in one reported patient. Because RIPK1 is expressed well beyond the haematopoietic compartment, the fact that replacing that compartment alone was sufficient is itself a mechanistic result and not only a therapeutic one. The evidence base is a single patient.
Mechanism Target:
Defective T and B Cell Differentiation — Replacing the haematopoietic compartment supplies lymphoid progenitors with intact RIPK1.
Show evidence (1 reference)
PMID:30026316 SUPPORT Human Clinical
"Hematopoietic stem cell transplantation reversed cytokine production defects and resolved clinical symptoms in one patient."
The rescue, in a patient. It is one patient, which is why this entry does not state transplantation as established therapy.
Show evidence (3 references)
PMID:30026316 SUPPORT Human Clinical
"Hematopoietic stem cell transplantation reversed cytokine production defects and resolved clinical symptoms in one patient."
The single reported transplant outcome.
PMID:34163478 SUPPORT REVIEW SYNTHESIS Other
"HSCT has resolved the inflammatory manifestations and reduced the frequency of infections in one RIPK1-deficient patient"
The review's independent statement of the same single-patient result, which is useful because it names what transplantation resolved (the inflammatory manifestations and the infection frequency) rather than only that symptoms resolved.
PMID:34163478 SUPPORT REVIEW SYNTHESIS Other
"| family 1 | P2 | Pakistan | M | 867_870delTTTA | Y289* | 1 mo. | RLRR | Y | N | N | Y | N | N | N | N | severe RSV bronchiolitis, RI | HSCT | Alive |"
Table 1, patient P2: transplanted and alive. Four of the fourteen recessive patients were transplanted (P1, P2, P3 and P7) and three of those four died, which is the counterweight to the single published success and the reason this entry does not present transplantation as established therapy.
Immunoglobulin replacement
Action: immunoglobulin therapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is immunoglobulin therapy (NCIT:C62710). NCIT:C62710 is a clinical intervention from the NCI Thesaurus. Ontology label: Immunoglobulin Therapy NCIT:C62710
Platform: Protein replacement
Intravenous immunoglobulin is recorded for two of the fourteen recessive patients in the review's Table 1 (P4 and P14). It replaces the antibody output the B cell differentiation defect removes and is supportive rather than disease-directed: it does nothing about the autoinflammatory arm, and P14 died while receiving it.
Show evidence (2 references)
PMID:34163478 SUPPORT REVIEW SYNTHESIS Other
"| family 3 | P4 | Arab | F | 460-133_689-244del | DELexon5 | 2 yrs. | LLLL | Y | N | N | Y | N | N | N | N | severe RSV bronchiolitis, recurrent OM | IVIG | Alive |"
Table 1, patient P4: the `Treatments` column reads IVIG. The table legend expands the abbreviation.
PMID:34163478 SUPPORT REVIEW SYNTHESIS Other
"Ab, antibiotics; AF, antifungal; AZA, azathioprine; CS, corticosteroids; IBD, inflammatory bowel disease; IFX, infliximab; IVIG, intravenous immunoglobulin"
The legend that makes the treatment abbreviations in Table 1 readable, and the reason the rows quoted across this section can be interpreted at all.
Systemic corticosteroid therapy
Action: systemic corticosteroid therapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is systemic corticosteroid therapy (NCIT:C122080). NCIT:C122080 is a clinical intervention from the NCI Thesaurus. Ontology label: Systemic Corticosteroid Therapy NCIT:C122080
Platform: Small molecule
Corticosteroids are recorded for four of the fourteen recessive patients (P5, P7, P9 and P12) in the review's Table 1, used against the inflammatory manifestations. No outcome is attributed to them in the table, and two of the four patients who received them died, so this records practice rather than efficacy.
Show evidence (1 reference)
PMID:34163478 SUPPORT REVIEW SYNTHESIS Other
"| family 9 | P12 | North Africa | F | 1802G>A | C601Y | 3 mos. | LLLL | Y | N | N | N | N | N | N | Y | OM, tetany, perianal disease | Ab, AF, CS | Alive |"
Table 1, patient P12: the `Treatments` column reads Ab, AF, CS, where CS is corticosteroids in the table legend.
Azathioprine
Action: PharmacotherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Pharmacotherapy (NCIT:C15986). NCIT:C15986 is a clinical intervention from the NCI Thesaurus. NCIT:C15986
Agent: azathioprine NCIT:C290 NCI Thesaurus (NCIT) Relation: this treatment uses this therapeutic agent This treatment uses azathioprine (NCIT:C290). NCIT:C290 is a therapeutic agent from the NCI Thesaurus.
Platform: Small molecule
Two of the fourteen recessive patients (P5 and P9) received azathioprine together with infliximab, antibiotics and corticosteroids, which is conventional inflammatory bowel disease management rather than anything specific to RIPK1. P5 died; P9 was alive at the time of writing. Azathioprine and infliximab are curated as separate treatments because their modalities differ and the slot takes one value, not because the source separates them.
Show evidence (2 references)
PMID:34163478 SUPPORT REVIEW SYNTHESIS Other
"| family 4 | P5 | Caucasian | M | 1844T>C | I615T | 6 mos. | LLLR | Y | Y | Y | N | Y | N | N | Y | sepsis, esophagitis, gastritis, perianal disease | Ab, AZA, CS, IFX | Died |"
Table 1, patient P5: the `Treatments` column reads Ab, AZA, CS, IFX, which the legend expands to antibiotics, azathioprine, corticosteroids and infliximab.
PMID:34163478 SUPPORT REVIEW SYNTHESIS Other
"| family 8 | P9 | Arab | F | 1934C>T | T645M | 1 day | n.r. | Y | N | N | Y | Y | N | N | Y | OM, esophagitis, UTI, perianal disease | Ab, AZA, CS, IFX | Alive |"
Patient P9, the second patient on the same four-agent combination, and the one who survived it.
Infliximab
Action: PharmacotherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Pharmacotherapy (NCIT:C15986). NCIT:C15986 is a clinical intervention from the NCI Thesaurus. NCIT:C15986
Agent: infliximab NCIT:C1789 NCI Thesaurus (NCIT) Relation: this treatment uses this therapeutic agent This treatment uses infliximab (NCIT:C1789). NCIT:C1789 is a therapeutic agent from the NCI Thesaurus.
Platform: Monoclonal antibody
Given with azathioprine to the same two patients. Infliximab blocks TNF, and using it in a disease whose lesion already blunts TNFR1-to-NF-kappaB signalling is a mechanistic oddity that no located source comments on. That is recorded rather than resolved: nothing here supports saying whether the drug helps, harms, or reaches the autoinflammatory arm by some route the signalling defect leaves intact.
Show evidence (2 references)
PMID:34163478 SUPPORT REVIEW SYNTHESIS Other
"| family 4 | P5 | Caucasian | M | 1844T>C | I615T | 6 mos. | LLLR | Y | Y | Y | N | Y | N | N | Y | sepsis, esophagitis, gastritis, perianal disease | Ab, AZA, CS, IFX | Died |"
Table 1, patient P5: the `Treatments` column reads Ab, AZA, CS, IFX, which the legend expands to antibiotics, azathioprine, corticosteroids and infliximab.
PMID:34163478 SUPPORT REVIEW SYNTHESIS Other
"| family 8 | P9 | Arab | F | 1934C>T | T645M | 1 day | n.r. | Y | N | N | Y | Y | N | N | Y | OM, esophagitis, UTI, perianal disease | Ab, AZA, CS, IFX | Alive |"
Patient P9, the second patient on the same four-agent combination, and the one who survived it.
Antibiotic therapy
Action: antibiotic therapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is antibiotic therapy (NCIT:C15620). NCIT:C15620 is a clinical intervention from the NCI Thesaurus. Ontology label: Antibiotic Therapy NCIT:C15620
Platform: Small molecule
Antibiotics are the most frequently recorded treatment in the review's Table 1, in seven of fourteen recessive patients (P5, P6, P9, P10, P11, P12 and P14). Given a cohort whose commonest manifestations are pneumonia, otitis media and perianal disease, this is treatment of the infection burden rather than prophylaxis; the table does not distinguish the two.
Show evidence (1 reference)
PMID:34163478 SUPPORT REVIEW SYNTHESIS Other
"| family 9 | P10 | North Africa | M | 1802G>A | C601Y | 6 mos. | LLRL | Y | N | N | N | Y | N | N | Y | OM, perianal disease, omphalitis | Ab, AF | Alive |"
Table 1, patient P10: the `Treatments` column reads Ab, AF. The same row records otitis media, perianal disease and omphalitis, which is the burden being treated.
Antifungal therapy
Action: antifungal therapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is antifungal therapy (NCIT:C15704). NCIT:C15704 is a clinical intervention from the NCI Thesaurus. Ontology label: Antifungal Therapy NCIT:C15704
Platform: Small molecule
Antifungals are recorded for the three affected siblings of family 9 (P10, P11 and P12) in the review's Table 1, and for no one else. A treatment confined to one family is as likely to reflect that centre's practice as the disease, which is why it is recorded without a frequency claim.
Show evidence (1 reference)
PMID:34163478 SUPPORT REVIEW SYNTHESIS Other
"| family 9 | P11 | North Africa | M | 1802G>A | C601Y | 20 days | LLLL | Y | N | N | N | Y | N | N | Y | OM, tetany, perianal disease | Ab, AF | Alive |"
Table 1, patient P11: the `Treatments` column reads Ab, AF, where AF is antifungal in the legend.
Interleukin-1 inhibition
Action: PharmacotherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Pharmacotherapy (NCIT:C15986). NCIT:C15986 is a clinical intervention from the NCI Thesaurus. NCIT:C15986
Proposed, not reported. The review argues that IL-1 inhibitors may help the inflammatory manifestations, which follows directly from the raised IL-1 beta output on the inflammasome node, and no patient in its own table received one. It is recorded here as a mechanistically motivated proposal so that the pathograph and the therapeutic suggestion stay attached; the specific agent is not named by the source, so none is bound.
Mechanism Target:
Increased Inflammasome Activity — The proposal targets this node specifically: the inflammatory arm is attributed to NLRP3 activation with high IL-1 beta output, and blocking IL-1 is the direct countermeasure to that output. It would leave the signalling-loss arm untouched.
Show evidence (1 reference)
PMID:34163478 SUPPORT REVIEW SYNTHESIS Other
"In patients with RIPK1 deficiency, treatment with IL-1 inhibitors may ameliorate the inflammatory manifestations."
The same sentence, quoted here for the mechanism the proposal acts on rather than for the proposal itself.
Show evidence (1 reference)
PMID:34163478 SUPPORT REVIEW SYNTHESIS Other
"In patients with RIPK1 deficiency, treatment with IL-1 inhibitors may ameliorate the inflammatory manifestations."
The proposal, in the review's own words. It is a suggestion in a discussion section, with no trial, no case report and no patient behind it, and the treatment description says so.
🔬

Biochemical Markers

1
Whole-blood cytokine production assay
Pathograph Readouts
Readout Of Impaired NF-kappaB and MAPK Signalling Diagnostic
Complex I signalling is what drives cytokine transcription downstream of TNFR1, so a whole-blood cytokine profile is the accessible functional readout of the signalling defect.
Show evidence (1 reference)
PMID:30026316 SUPPORT Human Clinical
"They had immunodeficiency with lymphopenia and altered production of various cytokines revealed by whole-blood assays."
Names the assay and the abnormality it detects, in the patients.
Pharmacodynamic Marker Of Defective T and B Cell Differentiation Monitoring
The cytokine production defect reversed after haematopoietic stem cell transplantation, so the assay tracks correction of the haematopoietic compartment rather than only confirming the diagnosis.
Show evidence (1 reference)
PMID:30026316 SUPPORT Human Clinical
"Hematopoietic stem cell transplantation reversed cytokine production defects and resolved clinical symptoms in one patient."
The reversal, in one patient. A single observation, which is why the interpretation says tracks rather than validates.
Show evidence (1 reference)
PMID:30026316 SUPPORT In Vitro
"In vitro, RIPK1-deficient cells showed impaired mitogen-activated protein kinase activation and cytokine secretion and were prone to necroptosis."
The cell-level counterpart of the whole-blood finding, measured in patient cells.
🔬

Diagnosis

3
RIPK1 sequencing
Molecular confirmation. Biallelic loss-of-function variants are the diagnosis, and the zygosity is not incidental detail: a heterozygous RIPK1 variant at the caspase-8 cleavage site Asp324 indicates a different, dominantly inherited hyperinflammatory disease rather than a milder form of this one, so a report that stops at "RIPK1 variant found" is not a diagnosis.
Show evidence (2 references)
PMID:30591564 SUPPORT Human Clinical
"Here, we report on eight patients from six unrelated pedigrees with biallelic loss-of-function mutations in RIPK1 presenting with primary immunodeficiency and/or intestinal inflammation."
The genotype that defines the disease, with the biallelic requirement explicit.
PMID:34163478 SUPPORT REVIEW SYNTHESIS Other
"This review discusses the molecular pathogenesis of RIPK1-deficiency and cleavage-resistant RIPK1 induced autoinflammatory (CRIA) disorders and summarizes the clinical manifestations of respective diseases to help with the identification of new patients."
Places the two RIPK1 diseases side by side, which is what makes reading the zygosity part of the diagnostic step rather than an afterthought.
Whole-blood cytokine production assay
The functional test. Whole-blood stimulation assays revealed altered production of various cytokines in the founding patients, and the same measurement normalised after transplantation. It is accessible in a way the cell-level work is not.
Markers: Multiple cytokines on whole-blood stimulation; the entry's biochemical section carries this as a readout of the signalling node.
Show evidence (1 reference)
PMID:30026316 SUPPORT Human Clinical
"They had immunodeficiency with lymphopenia and altered production of various cytokines revealed by whole-blood assays."
The assay and its abnormal result in the founding cohort.
Lymphocyte count
Lymphopenia is the other laboratory feature named in the disease definition and is the cheapest abnormality to detect, though it is not specific to this disease.
Show evidence (1 reference)
PMID:30026316 SUPPORT Human Clinical
"They had immunodeficiency with lymphopenia and altered production of various cytokines revealed by whole-blood assays."
Lymphopenia in the founding cohort.
📈

Progression

2
Infantile onset
Presentation is in the first year of life, with recurrent infections and gastrointestinal inflammation. The arthritis is described as progressive rather than static, which is what separates the joint disease here from a transient post-infectious arthritis.
Show evidence (1 reference)
PMID:30026316 SUPPORT Human Clinical
"The patients suffered from recurrent infections, early-onset inflammatory bowel disease, and progressive polyarthritis."
The presenting triad. "Early-onset" and "progressive" are the paper's own words for the timing.
Outcome in the published cohort
Six of the fourteen patients with recessive RIPK1 deficiency tabulated in the 2021 review had died at the time of writing (P1, P3, P5, P7, P8 and P14), seven were alive and one outcome was not reported. That count is a tabulation of the `Outcome` column rather than a figure the review states, and it is a published-case series with the ascertainment bias that implies, so it bounds severity rather than estimating survival. Four of the six deaths occurred in patients who had received a transplant or immunosuppression, which is why this entry does not present either as established therapy.
Show evidence (3 references)
PMID:34163478 SUPPORT REVIEW SYNTHESIS Other
"patients with RIPK1 biallelic LoF mutations were born alive, however, they suffered from severe and potentially lethal immunodeficiency"
The review's own characterisation of the disease's severity, which is the claim this phase records. The per-patient outcomes below are the tabulated form of it.
PMID:34163478 SUPPORT REVIEW SYNTHESIS Other
"| family 1 | P1 | Pakistan | M | 867_870delTTTA | Y289* | 1 mo. | LLLR | Y | N | N | Y | Y | N | N | N | bronchiectasis, HCMV, recurrent RI | HSCT | Died |"
Table 1, patient P1: the `Outcome` column reads Died, despite transplantation. P1's brother P2 received the same treatment and survived, which is the clearest statement in the table that outcome is not determined by genotype alone.
PMID:34163478 SUPPORT REVIEW SYNTHESIS Other
"| family 6 | P7 | Caucasian | F | 1278C>A | Y426* | 1 day | LLLL | Y | Y | Y | N | N | N | N | N | GI infections, U/LRI, septicemia, hepatitis | CS, HSCT | Died |"
Patient P7, the second transplanted patient who died. Four of the six deaths (P1, P3, P5 and P7) were in patients who had received transplantation or immunosuppression.
📊

Prevalence

1
Patients reported in the two founding series
Cases In Literature Ultra Rare
Four patients from three families in the first report and eight patients from six pedigrees in the second, with further single cases since. No population prevalence has been estimated, and none of the located sources offers a denominator, so the ULTRA_RARE band rests on the published case count rather than on a measured rate.
Show evidence (1 reference)
PMID:30026316 SUPPORT Human Clinical
"We report four patients from three unrelated families with complete RIPK1 deficiency caused by rare homozygous mutations."
The case count in the founding report.
{ }

Source YAML

click to show 
name: Immunodeficiency 57
creation_date: "2026-09-17T14:40:00Z"
description: >-
  Immunodeficiency 57 with autoinflammation (IMD57) is the autosomal recessive
  disease caused by biallelic loss-of-function variants in RIPK1, and it is
  unusual in combining immunodeficiency with autoinflammation in the same
  patient. RIPK1 sits immediately downstream of TNFR1 in signalling complex I,
  where it does two different jobs: as a scaffold it supports the ubiquitination
  events that route the signal into NF-kappaB and MAPK activation and so keep the
  cell alive, and as a kinase it can instead drive the cell into apoptosis or, when
  caspase-8 is unavailable, necroptosis. Losing the protein therefore removes a
  pro-survival signal and a cell-death brake at once. The consequences are
  correspondingly two-sided: reduced NF-kappaB activity with defective T- and
  B-cell differentiation and impaired cytokine secretion on one side, and increased
  inflammasome activity with cells prone to necroptosis on the other. Patients
  present in the first year of life with recurrent bacterial, viral and fungal
  infections, early-onset inflammatory bowel disease, progressive polyarthritis
  and lymphopenia. Only a few families have been reported. Haematopoietic stem
  cell transplantation corrected the cytokine production defect and resolved the
  clinical picture in one reported patient, which is the strongest evidence that
  the disease is driven by the haematopoietic compartment.
synonyms:
- IMD57
- immunodeficiency 57 with autoinflammation
- RIPK1 deficiency
- human RIPK1 deficiency
category: Mendelian
disease_term:
  preferred_term: immunodeficiency 57
  term:
    id: MONDO:0020849
    label: immunodeficiency 57
mappings:
  mondo_mappings:
  - term:
      id: MONDO:0020849
      label: immunodeficiency 57
    mapping_predicate: skos:exactMatch
    mapping_source: MONDO
parents:
- inborn error of immunity
- autosomal recessive disease
- rare disease
inheritance:
- name: Autosomal recessive inheritance
  inheritance_term:
    preferred_term: Autosomal recessive inheritance
    term:
      id: HP:0000007
      label: Autosomal recessive inheritance
  description: >-
    IMD57 requires two defective RIPK1 alleles. Reported patients have been
    homozygous, several from consanguineous families. Heterozygous carriers are
    unaffected. The distinction from the dominant disease at the same locus is not
    one of dosage but of consequence: cleavage-resistant RIPK1 variants at Asp324
    act in the heterozygous state and cause a hyperinflammatory disease, not this one.
  evidence:
  - reference: PMID:30026316
    reference_title: Biallelic RIPK1 mutations in humans cause severe immunodeficiency, arthritis, and intestinal inflammation.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      We report four patients from three unrelated families with complete RIPK1
      deficiency caused by rare homozygous mutations.
    explanation: >-
      The founding cohort, establishing homozygous loss of function as the genotype.
  - reference: PMID:30591564
    reference_title: Human RIPK1 deficiency causes combined immunodeficiency and inflammatory bowel diseases.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Here, we report on eight patients from six unrelated pedigrees with biallelic
      loss-of-function mutations in RIPK1 presenting with primary immunodeficiency
      and/or intestinal inflammation.
    explanation: >-
      Independent replication in a second, larger series, with the same biallelic
      loss-of-function requirement.
prevalence:
- population: Patients reported in the two founding series
  measure_type: CASES_IN_LITERATURE
  prevalence_class: ULTRA_RARE
  notes: >-
    Four patients from three families in the first report and eight patients from
    six pedigrees in the second, with further single cases since. No population
    prevalence has been estimated, and none of the located sources offers a
    denominator, so the ULTRA_RARE band rests on the published case count rather
    than on a measured rate.
  evidence:
  - reference: PMID:30026316
    reference_title: Biallelic RIPK1 mutations in humans cause severe immunodeficiency, arthritis, and intestinal inflammation.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      We report four patients from three unrelated families with complete RIPK1
      deficiency caused by rare homozygous mutations.
    explanation: The case count in the founding report.
progression:
- phase: Infantile onset
  notes: >-
    Presentation is in the first year of life, with recurrent infections and
    gastrointestinal inflammation. The arthritis is described as progressive rather
    than static, which is what separates the joint disease here from a transient
    post-infectious arthritis.
  evidence:
  - reference: PMID:30026316
    reference_title: Biallelic RIPK1 mutations in humans cause severe immunodeficiency, arthritis, and intestinal inflammation.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The patients suffered from recurrent infections, early-onset inflammatory
      bowel disease, and progressive polyarthritis.
    explanation: >-
      The presenting triad. "Early-onset" and "progressive" are the paper's own
      words for the timing.
- phase: Outcome in the published cohort
  notes: >-
    Six of the fourteen patients with recessive RIPK1 deficiency tabulated in the 2021
    review had died at the time of writing (P1, P3, P5, P7, P8 and P14), seven were
    alive and one outcome was not reported. That count is a tabulation of the `Outcome`
    column rather than a figure the review states, and it is a published-case series
    with the ascertainment bias that implies, so it bounds severity rather than
    estimating survival. Four of the six deaths occurred in patients who had received a
    transplant or immunosuppression, which is why this entry does not present either as
    established therapy.
  evidence:
  - reference: PMID:34163478
    reference_title: RIPK1-Associated Inborn Errors of Innate Immunity.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      patients with RIPK1 biallelic LoF mutations were born alive, however, they
      suffered from severe and potentially lethal immunodeficiency
    explanation: >-
      The review's own characterisation of the disease's severity, which is the claim
      this phase records. The per-patient outcomes below are the tabulated form of it.
    quote_role: REVIEW_SYNTHESIS
  - reference: PMID:34163478
    reference_title: RIPK1-Associated Inborn Errors of Innate Immunity.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      | family 1 | P1 | Pakistan | M | 867_870delTTTA | Y289* | 1 mo. | LLLR | Y | N | N
      | Y | Y | N | N | N | bronchiectasis, HCMV, recurrent RI | HSCT | Died |
    explanation: >-
      Table 1, patient P1: the `Outcome` column reads Died, despite transplantation.
      P1's brother P2 received the same treatment and survived, which is the clearest
      statement in the table that outcome is not determined by genotype alone.
    quote_role: REVIEW_SYNTHESIS
  - reference: PMID:34163478
    reference_title: RIPK1-Associated Inborn Errors of Innate Immunity.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      | family 6 | P7 | Caucasian | F | 1278C>A | Y426* | 1 day | LLLL | Y | Y | Y | N |
      N | N | N | N | GI infections, U/LRI, septicemia, hepatitis | CS, HSCT | Died |
    explanation: >-
      Patient P7, the second transplanted patient who died. Four of the six deaths (P1,
      P3, P5 and P7) were in patients who had received transplantation or
      immunosuppression.
    quote_role: REVIEW_SYNTHESIS
pathophysiology:
- name: RIPK1 Loss of Function
  biological_scale: MOLECULAR
  description: >-
    Biallelic loss-of-function variants abolish RIPK1 protein. RIPK1 is a 75.9 kDa
    protein with an N-terminal kinase domain, a C-terminal death domain and an
    intermediate domain carrying a RIP homotypic interaction motif, and it is
    recruited with TRADD to TNFR1 to form signalling complex I. Because the protein
    carries both a scaffolding role and a kinase role, its complete absence removes
    two opposing functions simultaneously, which is why the resulting disease is
    not simply a loss of inflammation or a gain of it.
  genes:
  - preferred_term: RIPK1
    term:
      id: hgnc:10019
      label: RIPK1
  genetic_context:
    variant_origin: GERMLINE
    zygosity: HOMOZYGOUS
    functional_impact_category: LOSS_OF_FUNCTION
  downstream:
  - target: Impaired NF-kappaB and MAPK Signalling
    causal_link_type: DIRECT
    description: >-
      RIPK1 is a component of complex I, whose ubiquitination provides the docking
      platform for the kinases that activate NF-kappaB and MAPK. Without RIPK1 that
      platform is not assembled.
    evidence:
    - reference: PMID:30591564
      reference_title: Human RIPK1 deficiency causes combined immunodeficiency and inflammatory bowel diseases.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Mutations in RIPK1 were associated with reduced NF-κB activity, defective
        differentiation of T and B cells, increased inflammasome activity, and
        impaired response to TNFR1-mediated cell death in intestinal epithelial cells.
      explanation: >-
        Measures reduced NF-kappaB activity directly in patients carrying the
        mutations, which is the step this edge asserts.
  - target: Necroptosis Susceptibility
    causal_link_type: DIRECT
    description: >-
      Losing RIPK1 does not abolish cell death but redirects it. Patient cells were
      prone to necroptosis in vitro.
    evidence:
    - reference: PMID:30026316
      reference_title: Biallelic RIPK1 mutations in humans cause severe immunodeficiency, arthritis, and intestinal inflammation.
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: >-
        In vitro, RIPK1-deficient cells showed impaired mitogen-activated protein
        kinase activation and cytokine secretion and were prone to necroptosis.
      explanation: >-
        The necroptosis susceptibility is measured in the patients' own cells, so
        the edge is not inferred from a model system.
  - target: Increased Inflammasome Activity
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >-
      Inflammasome activity is increased rather than decreased in RIPK1-deficient
      patients. The route is not established: a non-canonical
      TLR4-TRIF-RIPK1-FADD-caspase-8 axis has been proposed, and this entry does not
      assert it.
    evidence:
    - reference: PMID:30591564
      reference_title: Human RIPK1 deficiency causes combined immunodeficiency and inflammatory bowel diseases.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Mutations in RIPK1 were associated with reduced NF-κB activity, defective
        differentiation of T and B cells, increased inflammasome activity, and
        impaired response to TNFR1-mediated cell death in intestinal epithelial cells.
      explanation: >-
        Establishes that inflammasome activity rises, which is the claim; the same
        sentence says nothing about the route, which is why the link type is not DIRECT.
  evidence:
  - reference: PMID:34163478
    reference_title: RIPK1-Associated Inborn Errors of Innate Immunity.
    supports: SUPPORT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    snippet: >-
      RIPK1 is a 75.9 kDa protein with an amino-terminal kinase domain (KD), a
      carboxy-terminal death domain (DD), and an intermediate domain (ID) in-between
      which contains a Rip homotypic interaction motif (RHIM).
    explanation: >-
      The domain architecture behind the dual scaffold/kinase role. This is the
      review's synthesis of established structural work, not its own result.
- name: Impaired NF-kappaB and MAPK Signalling
  biological_scale: CELLULAR
  description: >-
    Complex I normally routes the TNFR1 signal into NF-kappaB and MAPK activation,
    producing pro-inflammatory cytokines and promoting survival. In RIPK1-deficient
    cells both arms are blunted: MAPK activation and cytokine secretion are impaired.
    This is the immunodeficiency half of the disease.
  biological_processes:
  - preferred_term: canonical NF-kappaB signal transduction
    modifier: DECREASED
    term:
      id: GO:0007249
      label: canonical NF-kappaB signal transduction
  - preferred_term: MAPK cascade
    modifier: DECREASED
    term:
      id: GO:0000165
      label: MAPK cascade
  - preferred_term: cytokine production
    modifier: DECREASED
    term:
      id: GO:0001816
      label: cytokine production
  cell_types:
  - preferred_term: patient-derived fibroblast
    term:
      id: CL:0000057
      label: fibroblast
  downstream:
  - target: Defective T and B Cell Differentiation
    causal_link_type: DIRECT
    description: >-
      NF-kappaB signalling is required for lymphocyte development, and its reduction
      in these patients is accompanied by defective differentiation of both lineages.
    evidence:
    - reference: PMID:30591564
      reference_title: Human RIPK1 deficiency causes combined immunodeficiency and inflammatory bowel diseases.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Mutations in RIPK1 were associated with reduced NF-κB activity, defective
        differentiation of T and B cells, increased inflammasome activity, and
        impaired response to TNFR1-mediated cell death in intestinal epithelial cells.
      explanation: >-
        The reduced NF-kappaB activity and the differentiation defect are reported in
        the same patients, in that order.
  evidence:
  - reference: PMID:30026316
    reference_title: Biallelic RIPK1 mutations in humans cause severe immunodeficiency, arthritis, and intestinal inflammation.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      In vitro, RIPK1-deficient cells showed impaired mitogen-activated protein
      kinase activation and cytokine secretion and were prone to necroptosis.
    explanation: Measures the MAPK and cytokine arms in patient cells.
- name: Defective T and B Cell Differentiation
  biological_scale: CELLULAR
  description: >-
    Both lymphocyte lineages differentiate abnormally, which is the cellular basis
    of the lymphopenia and of the susceptibility to bacterial, viral and fungal
    organisms alike. A defect confined to one lineage would not produce that breadth.
  cell_types:
  - preferred_term: T cell
    term:
      id: CL:0000084
      label: T cell
  - preferred_term: B cell
    term:
      id: CL:0000236
      label: B cell
  downstream:
  - target: Lymphopenia
    causal_link_type: DIRECT
  - target: Recurrent infections
    causal_link_type: DIRECT
    description: >-
      Defective differentiation of both lymphocyte lineages leaves the patient unable
      to mount adequate adaptive responses, which is the immunodeficiency the patients
      present with.
    evidence:
    - reference: PMID:30026316
      reference_title: Biallelic RIPK1 mutations in humans cause severe immunodeficiency, arthritis, and intestinal inflammation.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        They had immunodeficiency with lymphopenia and altered production of various
        cytokines revealed by whole-blood assays.
      explanation: >-
        Ties the immunodeficiency and the lymphopenia together in the same patients.
  - target: Pneumonia
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    description: >-
      Pneumonia is the commonest single infection recorded in the published cohort,
      in eight of fourteen patients, and it follows the lymphocyte differentiation
      defect by the ordinary route from immunodeficiency to lower respiratory tract
      infection. The intermediates are known in general terms and are not specific
      to this disease.
    evidence:
    - reference: PMID:34163478
      reference_title: RIPK1-Associated Inborn Errors of Innate Immunity.
      supports: SUPPORT
      evidence_source: OTHER
      snippet: >-
        | family 1 | P1 | Pakistan | M | 867_870delTTTA | Y289* | 1 mo. | LLLR | Y | N |
        N | Y | Y | N | N | N | bronchiectasis, HCMV, recurrent RI | HSCT | Died |
      explanation: >-
        Table 1, patient P1: the `Pneumonia` column reads Y. Pneumonia is recorded for
        eight of the fourteen recessive patients in that table (P1, P3, P5, P6, P9, P10,
        P11 and P14), counted column by column, which is the basis for the frequency
        band on the phenotype.
      quote_role: REVIEW_SYNTHESIS
  evidence:
  - reference: PMID:30591564
    reference_title: Human RIPK1 deficiency causes combined immunodeficiency and inflammatory bowel diseases.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Mutations in RIPK1 were associated with reduced NF-κB activity, defective
      differentiation of T and B cells, increased inflammasome activity, and
      impaired response to TNFR1-mediated cell death in intestinal epithelial cells.
    explanation: The differentiation defect in both lineages.
- name: Necroptosis Susceptibility
  biological_scale: CELLULAR
  description: >-
    RIPK1-deficient cells are prone to necroptosis. Necroptosis is lytic and
    releases intracellular contents, so a tissue whose cells die this way generates
    inflammation rather than being cleared quietly, which is one route by which the
    loss of a pro-survival signal produces an inflammatory phenotype.
  biological_processes:
  - preferred_term: necroptotic signaling pathway
    modifier: INCREASED
    term:
      id: GO:0097527
      label: necroptotic signaling pathway
  downstream:
  - target: Intestinal Epithelial Injury and Inflammation
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >-
      The intestinal epithelium is where the cell-death handling defect is
      demonstrated in these patients, and where the clinical consequence is most
      conspicuous. The intervening steps between the altered death response and the
      established colitis are not resolved in the cited work.
    evidence:
    - reference: PMID:30591564
      reference_title: Human RIPK1 deficiency causes combined immunodeficiency and inflammatory bowel diseases.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Mutations in RIPK1 were associated with reduced NF-κB activity, defective
        differentiation of T and B cells, increased inflammasome activity, and
        impaired response to TNFR1-mediated cell death in intestinal epithelial cells.
      explanation: >-
        Locates the impaired cell-death response specifically in intestinal epithelial
        cells, which is what makes the gut the site of this edge.
  - target: Increased Inflammasome Activity
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    description: >-
      The necroptotic machinery is part of how the raised IL-1 beta output is
      produced, not merely a parallel consequence of the same lesion: blocking MLKL
      reduces IL-1 beta secretion in RIPK1-deficient cells, as does blocking NLRP3.
      That pharmacological result is what makes this an edge rather than two
      independent arms.
    evidence:
    - reference: PMID:34163478
      reference_title: RIPK1-Associated Inborn Errors of Innate Immunity.
      supports: SUPPORT
      evidence_source: OTHER
      snippet: >-
        The altered IL-1β release has been associated with increased NLPR3 activity and
        MLKL-dependent necroptosis, based on evidence that inhibitors of NLRP3 or MLKL
        can reduce IL-1β secretion in LPS-stimulated RIPK1-deficient cell lines (BLaER1
        and THP1 cells)
      explanation: >-
        Both inhibitor arms are reported together, which is what licenses the direction
        of this edge. MLKL is the necroptosis executioner, so its inhibition reducing
        IL-1 beta places necroptosis upstream of the inflammasome output rather than
        beside it. The result is in cell lines, and the review is reporting it from the
        two primary papers.
      quote_role: REVIEW_SYNTHESIS
  evidence:
  - reference: PMID:30026316
    reference_title: Biallelic RIPK1 mutations in humans cause severe immunodeficiency, arthritis, and intestinal inflammation.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      In vitro, RIPK1-deficient cells showed impaired mitogen-activated protein
      kinase activation and cytokine secretion and were prone to necroptosis.
    explanation: The necroptosis susceptibility, measured in patient cells.
- name: Increased Inflammasome Activity
  biological_scale: CELLULAR
  biological_processes:
  - preferred_term: NLRP3 inflammasome complex assembly
    modifier: INCREASED
    term:
      id: GO:0044546
      label: NLRP3 inflammasome complex assembly
  description: >-
    Inflammasome activity is raised in RIPK1-deficient patients. This is the
    autoinflammatory half of the disease and the reason the entry is not simply an
    immunodeficiency: the same lesion that blunts one inflammatory output amplifies
    another.
  downstream:
  - target: Intestinal Epithelial Injury and Inflammation
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
  - target: Arthritis
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >-
      The polyarthritis is the joint manifestation of the autoinflammatory arm. No
      located source traces the steps from inflammasome activation to synovitis in
      these patients, so the edge is recorded with its intermediates unknown rather
      than as a mechanism.
  evidence:
  - reference: PMID:30591564
    reference_title: Human RIPK1 deficiency causes combined immunodeficiency and inflammatory bowel diseases.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Mutations in RIPK1 were associated with reduced NF-κB activity, defective
      differentiation of T and B cells, increased inflammasome activity, and
      impaired response to TNFR1-mediated cell death in intestinal epithelial cells.
    explanation: The increased inflammasome activity.
  - reference: PMID:34163478
    reference_title: RIPK1-Associated Inborn Errors of Innate Immunity.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      The inflammatory component of this disease is possibly related to the activation
      of NLRP3 inflammasome and high production of IL-1β cytokine
    explanation: >-
      Names the inflammasome as NLRP3 and the cytokine output as IL-1 beta, which is
      what the GO binding on this node records. The review states it as a possible
      attribution rather than a settled one, and the hedge is the review's own.
    quote_role: REVIEW_SYNTHESIS
  - reference: PMID:34163478
    reference_title: RIPK1-Associated Inborn Errors of Innate Immunity.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      In contrast, IL-1β production was markedly increased in PHA-stimulated patient’s
      blood
    explanation: >-
      The measurement behind the attribution: IL-1 beta rose markedly in stimulated
      patient blood, against a background of reduced IL-6, TNF and IL-12 in the same
      cells. That opposite direction is the argument for this node existing alongside
      the signalling-loss node rather than being folded into it.
    quote_role: REVIEW_SYNTHESIS
- name: Intestinal Epithelial Injury and Inflammation
  biological_scale: TISSUE
  description: >-
    The gut is the organ where the two arms of the disease meet. Intestinal
    epithelial cells respond abnormally to TNFR1-mediated death signals, and the
    result clinically is chronic inflammation of the digestive tract presenting in
    the first year of life.
  cell_types:
  - preferred_term: intestinal epithelial cell
    term:
      id: CL:0002563
      label: intestinal epithelial cell
  downstream:
  - target: Colitis
    causal_link_type: DIRECT
  - target: Failure to thrive
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    description: >-
      Chronic enteropathy impairs nutrient absorption and intake, and the infection
      burden adds to the energy deficit.
  evidence:
  - reference: PMID:30591564
    reference_title: Human RIPK1 deficiency causes combined immunodeficiency and inflammatory bowel diseases.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Mutations in RIPK1 were associated with reduced NF-κB activity, defective
      differentiation of T and B cells, increased inflammasome activity, and
      impaired response to TNFR1-mediated cell death in intestinal epithelial cells.
    explanation: >-
      Locates the defective death response in the intestinal epithelium, the cell type
      bound on this node.
phenotypes:
- category: Immunologic
  name: Recurrent infections
  description: >-
    Recurrent bacterial, viral and fungal infections beginning in the first year of
    life. The breadth across organism classes, rather than susceptibility to one
    class, is what points at a combined rather than a selective defect.

    The VERY_FREQUENT band reflects presence in every reported patient of the two
    founding series, not a published percentage, of which there is none.
  phenotype_term:
    preferred_term: Recurrent infections
    term:
      id: HP:0002719
      label: Recurrent infections
  frequency: VERY_FREQUENT
  evidence:
  - reference: PMID:30026316
    reference_title: Biallelic RIPK1 mutations in humans cause severe immunodeficiency, arthritis, and intestinal inflammation.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The patients suffered from recurrent infections, early-onset inflammatory
      bowel disease, and progressive polyarthritis.
    explanation: Recurrent infection in all four patients of the founding cohort.
- category: Immunologic
  name: Lymphopenia
  description: >-
    Reduced lymphocyte counts accompany the differentiation defect. It is one of the
    two laboratory features named in the disease definition, alongside the altered
    cytokine production.
  phenotype_term:
    preferred_term: Lymphopenia
    term:
      id: HP:0001888
      label: Decreased total lymphocyte count
  frequency: VERY_FREQUENT
  evidence:
  - reference: PMID:30026316
    reference_title: Biallelic RIPK1 mutations in humans cause severe immunodeficiency, arthritis, and intestinal inflammation.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      They had immunodeficiency with lymphopenia and altered production of various
      cytokines revealed by whole-blood assays.
    explanation: Lymphopenia in the founding cohort.
- category: Gastrointestinal
  name: Colitis
  description: >-
    Early-onset inflammatory bowel disease is one of the two presentations that
    bring these patients to attention, and in the second series intestinal
    inflammation occurred with or without the immunodeficiency being the leading
    problem.

    HPO has no term for inflammatory bowel disease as such, so Colitis is bound and
    the specificity is carried in preferred_term.
  phenotype_term:
    preferred_term: Early-onset inflammatory bowel disease
    term:
      id: HP:0002583
      label: Colitis
  frequency: VERY_FREQUENT
  evidence:
  - reference: PMID:30026316
    reference_title: Biallelic RIPK1 mutations in humans cause severe immunodeficiency, arthritis, and intestinal inflammation.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The patients suffered from recurrent infections, early-onset inflammatory
      bowel disease, and progressive polyarthritis.
    explanation: The gastrointestinal presentation in the founding cohort.
  - reference: PMID:30591564
    reference_title: Human RIPK1 deficiency causes combined immunodeficiency and inflammatory bowel diseases.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Here, we report on eight patients from six unrelated pedigrees with biallelic
      loss-of-function mutations in RIPK1 presenting with primary immunodeficiency
      and/or intestinal inflammation.
    explanation: >-
      Independent replication, and the "and/or" is the source of the note that the
      two presentations can occur separately.
- category: Gastrointestinal
  name: Gastritis
  description: >-
    Inflammation involves the upper as well as the lower gastrointestinal tract, so
    the enteropathy is not confined to the colon. No frequency is recorded for
    gastritis specifically in the located sources, so the slot is left empty rather
    than estimated.
  phenotype_term:
    preferred_term: Gastritis
    term:
      id: HP:0005263
      label: Gastritis
  frequency: OCCASIONAL
  evidence:
  - reference: PMID:34163478
    reference_title: RIPK1-Associated Inborn Errors of Innate Immunity.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      | family 4 | P5 | Caucasian | M | 1844T>C | I615T | 6 mos. | LLLR | Y | Y | Y | N
      | Y | N | N | Y | sepsis, esophagitis, gastritis, perianal disease | Ab, AZA, CS,
      IFX | Died |
    explanation: >-
      Table 1 of the review, patient P5. The `Others` column names gastritis explicitly.
      Gastritis is listed for three of the fourteen patients with recessive RIPK1
      deficiency in that table (P5, P8 and P13), which is the basis for the frequency
      band.
    quote_role: REVIEW_SYNTHESIS
  - reference: PMID:34163478
    reference_title: RIPK1-Associated Inborn Errors of Innate Immunity.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      | family 7 | P8 | Arab | F | 954delG | M318Ifs*194 | 1 day | LLLL | Y | N | N | N
      | N | N | N | N | esophagitis, gastritis, UTI, perianal disease | n.r. | Died |
    explanation: >-
      Patient P8, the second of the three rows naming gastritis. P8 carries a frameshift
      allele where P5 carries a missense one, so the finding is not confined to one
      variant class.
    quote_role: REVIEW_SYNTHESIS
  - reference: PMID:34163478
    reference_title: RIPK1-Associated Inborn Errors of Innate Immunity.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      | family 10 | P13 | South America | M | 636C>G | Y212* | 1 day | LLLL | Y | Y | Y
      | N | N | N | N | N | esophagitis, gastritis | n.r. | Alive |
    explanation: >-
      Patient P13, the third row. P13 survived where P5 and P8 did not, so gastritis is
      not only a feature of the fatal cases.
    quote_role: REVIEW_SYNTHESIS
- category: Musculoskeletal
  name: Arthritis
  description: >-
    Progressive polyarthritis, described as such in the founding cohort. It is the
    clearest autoinflammatory feature and the one that distinguishes this disease
    from a pure combined immunodeficiency.

    Graded FREQUENT rather than VERY_FREQUENT because the second series describes
    its patients as presenting with immunodeficiency and/or intestinal inflammation
    without naming arthritis in every case.
  phenotype_term:
    preferred_term: Progressive polyarthritis
    term:
      id: HP:0001369
      label: Arthritis
  frequency: FREQUENT
  evidence:
  - reference: PMID:30026316
    reference_title: Biallelic RIPK1 mutations in humans cause severe immunodeficiency, arthritis, and intestinal inflammation.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The patients suffered from recurrent infections, early-onset inflammatory
      bowel disease, and progressive polyarthritis.
    explanation: Polyarthritis in the founding cohort.
- category: Growth
  name: Failure to thrive
  description: >-
    Growth failure follows the chronic enteropathy and the infection burden. No
    frequency is stated for failure to thrive itself in the located sources.
  phenotype_term:
    preferred_term: Failure to thrive
    term:
      id: HP:0001508
      label: Failure to thrive
  evidence:
  - reference: PMID:31213653
    reference_title: Primary immunodeficiency with chronic enteropathy and developmental delay in a boy arising from a novel homozygous RIPK1 variant.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Here, we report a novel homozygous RIPK1 variant in a boy with immunodeficiency
      and chronic enteropathy.
    explanation: >-
      Chronic enteropathy in a genetically confirmed patient, which is the route to
      the growth failure.
- category: Neurologic
  name: Motor delay
  description: >-
    Severe motor delay in one reported patient, explicitly new to the phenotype at the
    time. This is a single case, so it is recorded as a described feature rather than as
    part of the core picture, and no mechanism node in this entry reaches it.
  phenotype_term:
    preferred_term: Severe motor delay
    term:
      id: HP:0001270
      label: Motor delay
  severity: SEVERE
  evidence:
  - reference: PMID:31213653
    reference_title: Primary immunodeficiency with chronic enteropathy and developmental delay in a boy arising from a novel homozygous RIPK1 variant.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Our patient exhibited severe motor delay and mild intellectual disability, which
      were previously unknown.
    explanation: >-
      The paper's own statement that this feature had not previously been associated
      with RIPK1 deficiency. The sentence names the motor and the cognitive feature
      separately, which is why they are curated as two phenotypes.
- category: Neurologic
  name: Mild intellectual disability
  description: >-
    Mild intellectual disability in the same single patient as the motor delay, and
    reported in the same sentence but as a distinct feature. Whether the two share a
    mechanism is not addressed by any located source.
  phenotype_term:
    preferred_term: Mild intellectual disability
    term:
      id: HP:0001256
      label: Mild intellectual disability
  evidence:
  - reference: PMID:31213653
    reference_title: Primary immunodeficiency with chronic enteropathy and developmental delay in a boy arising from a novel homozygous RIPK1 variant.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Our patient exhibited severe motor delay and mild intellectual disability, which
      were previously unknown.
    explanation: >-
      The same sentence, quoted for the cognitive half of what it reports.
- category: Gastrointestinal
  name: Oral ulcers
  description: >-
    Oral lesions or ulcers are recorded in six of the fourteen recessive patients in the
    review's Table 1 (P5, P9, P10, P11, P12 and P14), counted from the `Oral
    lesion/ulcers` column. Four of those six are the three North African siblings and
    P14, so the count is not six independent families and the frequency band should be
    read with that in mind. No located source connects the oral involvement to a
    mechanism in this entry's pathograph.
  phenotype_term:
    preferred_term: Oral lesions or ulcers
    term:
      id: HP:0000155
      label: Oral ulcer
  frequency: FREQUENT
  evidence:
  - reference: PMID:34163478
    reference_title: RIPK1-Associated Inborn Errors of Innate Immunity.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      | family 8 | P9 | Arab | F | 1934C>T | T645M | 1 day | n.r. | Y | N | N | Y | Y |
      N | N | Y | OM, esophagitis, UTI, perianal disease | Ab, AZA, CS, IFX | Alive |
    explanation: >-
      Table 1, patient P9: the `Oral lesion/ulcers` column reads Y.
    quote_role: REVIEW_SYNTHESIS
  - reference: PMID:34163478
    reference_title: RIPK1-Associated Inborn Errors of Innate Immunity.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      | family 9 | P10 | North Africa | M | 1802G>A | C601Y | 6 mos. | LLRL | Y | N | N
      | N | Y | N | N | Y | OM, perianal disease, omphalitis | Ab, AF | Alive |
    explanation: >-
      Patient P10, one of three affected siblings in family 9, all three of whom carry
      the finding. That clustering is why the description warns against reading the
      count as six independent observations.
    quote_role: REVIEW_SYNTHESIS
- category: Gastrointestinal
  name: Perianal disease
  description: >-
    Perianal disease is the single most frequent `Others` entry in the review's Table 1,
    recorded for eight of fourteen recessive patients (P5, P6, P8, P9, P10, P11, P12,
    and P14 as perianal abscess with anal fistula). It is left unbound deliberately: HPO
    carries the specific lesions (perianal abscess, anal fistula, perianal dermatitis)
    but no term for the aggregate the source reports, and binding one lesion type would
    narrow a claim the source does not make. The one patient whose lesions are itemised
    is quoted below.
  phenotype_term:
    preferred_term: Perianal disease
  frequency: FREQUENT
  evidence:
  - reference: PMID:34163478
    reference_title: RIPK1-Associated Inborn Errors of Innate Immunity.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      | family 9 | P11 | North Africa | M | 1802G>A | C601Y | 20 days | LLLL | Y | N | N
      | N | Y | N | N | Y | OM, tetany, perianal disease | Ab, AF | Alive |
    explanation: >-
      Table 1, patient P11: perianal disease in the `Others` column, reported as the
      aggregate rather than as a named lesion. This is the form seven of the eight rows
      take.
    quote_role: REVIEW_SYNTHESIS
  - reference: PMID:34163478
    reference_title: RIPK1-Associated Inborn Errors of Innate Immunity.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      | family 11 | P14 | Chinese | M | 998C>A 1934C>T | S333* T645M | 3 mos. | HLHL | Y
      | Y | Y | N | Y | Y | n.r. | Y | anemia, jaundice, perianal abscess, anal fistula,
      malnutrition | IVIG, Ab | Died |
    explanation: >-
      The exception: P14's lesions are itemised as perianal abscess and anal fistula.
      Both have HPO terms, but a single patient does not license binding the phenotype
      as a whole to either.
    quote_role: REVIEW_SYNTHESIS
- category: Gastrointestinal
  name: Esophagitis
  description: >-
    Esophagitis is recorded for four of the fourteen recessive patients (P5, P8, P9 and
    P13) in the review's Table 1. With gastritis it establishes that the mucosal
    inflammation reaches above the intestine, which the entry's pathophysiology does not
    explain: the located mechanism places the cell-death defect in intestinal epithelial
    cells.
  phenotype_term:
    preferred_term: Esophagitis
    term:
      id: HP:0100633
      label: Esophagitis
  frequency: OCCASIONAL
  evidence:
  - reference: PMID:34163478
    reference_title: RIPK1-Associated Inborn Errors of Innate Immunity.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      | family 8 | P9 | Arab | F | 1934C>T | T645M | 1 day | n.r. | Y | N | N | Y | Y |
      N | N | Y | OM, esophagitis, UTI, perianal disease | Ab, AZA, CS, IFX | Alive |
    explanation: >-
      Table 1, patient P9: esophagitis in the `Others` column.
    quote_role: REVIEW_SYNTHESIS
  - reference: PMID:34163478
    reference_title: RIPK1-Associated Inborn Errors of Innate Immunity.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      | family 10 | P13 | South America | M | 636C>G | Y212* | 1 day | LLLL | Y | Y | Y
      | N | N | N | N | N | esophagitis, gastritis | n.r. | Alive |
    explanation: >-
      Patient P13, who carries esophagitis and gastritis together, which is the pattern
      in three of the four rows.
    quote_role: REVIEW_SYNTHESIS
- category: Hepatic
  name: Hepatomegaly
  description: >-
    Hepatomegaly is recorded for four of the fourteen recessive patients (P5, P7, P13
    and P14) in the review's Table 1, in every case together with splenomegaly. The
    table scores the two as separate columns, so they are curated as two phenotypes
    rather than as hepatosplenomegaly; the exact co-occurrence is noted here rather than
    asserted as a combined finding.
  phenotype_term:
    preferred_term: Hepatomegaly
    term:
      id: HP:0002240
      label: Hepatomegaly
  frequency: OCCASIONAL
  evidence:
  - reference: PMID:34163478
    reference_title: RIPK1-Associated Inborn Errors of Innate Immunity.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      | family 6 | P7 | Caucasian | F | 1278C>A | Y426* | 1 day | LLLL | Y | Y | Y | N |
      N | N | N | N | GI infections, U/LRI, septicemia, hepatitis | CS, HSCT | Died |
    explanation: >-
      Table 1, patient P7: the `Hepato megaly` column reads Y.
    quote_role: REVIEW_SYNTHESIS
  - reference: PMID:34163478
    reference_title: RIPK1-Associated Inborn Errors of Innate Immunity.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      | family 10 | P13 | South America | M | 636C>G | Y212* | 1 day | LLLL | Y | Y | Y
      | N | N | N | N | N | esophagitis, gastritis | n.r. | Alive |
    explanation: >-
      Patient P13, the second of the four. P13's row also shows the splenomegaly column
      reading Y, which is the co-occurrence the description records.
    quote_role: REVIEW_SYNTHESIS
- category: Hematologic
  name: Splenomegaly
  description: >-
    Splenomegaly is recorded for the same four recessive patients as hepatomegaly (P5,
    P7, P13 and P14) in the review's Table 1. No located source attributes it to portal
    hypertension, to lymphoid hyperplasia, or to anything else, so no edge is drawn to
    it.
  phenotype_term:
    preferred_term: Splenomegaly
    term:
      id: HP:0001744
      label: Splenomegaly
  frequency: OCCASIONAL
  evidence:
  - reference: PMID:34163478
    reference_title: RIPK1-Associated Inborn Errors of Innate Immunity.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      | family 4 | P5 | Caucasian | M | 1844T>C | I615T | 6 mos. | LLLR | Y | Y | Y | N
      | Y | N | N | Y | sepsis, esophagitis, gastritis, perianal disease | Ab, AZA, CS,
      IFX | Died |
    explanation: >-
      Table 1, patient P5: the `Spleno megaly` column reads Y.
    quote_role: REVIEW_SYNTHESIS
  - reference: PMID:34163478
    reference_title: RIPK1-Associated Inborn Errors of Innate Immunity.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      | family 11 | P14 | Chinese | M | 998C>A 1934C>T | S333* T645M | 3 mos. | HLHL | Y
      | Y | Y | N | Y | Y | n.r. | Y | anemia, jaundice, perianal abscess, anal fistula,
      malnutrition | IVIG, Ab | Died |
    explanation: >-
      Patient P14, whose row also carries anemia and jaundice in the `Others` column,
      which is the one row where a haematological explanation is at least suggested.
    quote_role: REVIEW_SYNTHESIS
- category: Respiratory
  name: Pneumonia
  description: >-
    Pneumonia is the commonest single infection in the published cohort: eight of
    fourteen recessive patients (P1, P3, P5, P6, P9, P10, P11 and P14) in the review's
    Table 1. It is the manifestation that makes the immunodeficiency arm clinically
    dominant in infancy, and it is wired to the lymphocyte differentiation defect rather
    than to the autoinflammatory arm.
  phenotype_term:
    preferred_term: Pneumonia
    term:
      id: HP:0002090
      label: Pneumonia
  frequency: FREQUENT
  evidence:
  - reference: PMID:34163478
    reference_title: RIPK1-Associated Inborn Errors of Innate Immunity.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      | family 2 | P3 | Arab | F | 688_688+20del | N230Hfs*14 | 1 mo. | LLLL | Y | N | N
      | Y | Y | N | N | N | recurrent HSV1 infection | HSCT | Died |
    explanation: >-
      Table 1, patient P3: the `Pneumonia` column reads Y. This row also shows the
      recurrent HSV1 infection that sits beside the bacterial burden.
    quote_role: REVIEW_SYNTHESIS
  - reference: PMID:34163478
    reference_title: RIPK1-Associated Inborn Errors of Innate Immunity.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      | family 5 | P6 | Arab | F | 1934C>T | T645M | 1 mo. | RRRH | n.r. | n.r. | n.r. |
      N | Y | N | N | N | OM, U/LRI, perianal disease | Ab | n.r. |
    explanation: >-
      Patient P6, whose row shows pneumonia together with otitis media and upper and
      lower respiratory tract infections, which is the composite the `Recurrent
      infections` phenotype covers.
    quote_role: REVIEW_SYNTHESIS
biochemical:
- name: Whole-blood cytokine production assay
  notes: >-
    Altered production of multiple cytokines on whole-blood stimulation is one of the
    two laboratory features named in the disease definition, alongside the
    lymphopenia, and it is the measurement that reversed after transplantation. That
    makes it the entry's one functional readout that has been shown to respond to an
    intervention, which is a stronger claim than a marker that merely correlates with
    the genotype.

    The direction is "altered" rather than uniformly reduced: the sources describe
    dysregulated production across several cytokines, and the accompanying in-vitro
    work shows impaired secretion. This entry does not collapse that into a single
    direction, because no located source gives per-cytokine directions.
  readouts:
  - target: Impaired NF-kappaB and MAPK Signalling
    relationship: READOUT_OF
    endpoint_context: DIAGNOSTIC
    interpretation: >-
      Complex I signalling is what drives cytokine transcription downstream of TNFR1,
      so a whole-blood cytokine profile is the accessible functional readout of the
      signalling defect.
    evidence:
    - reference: PMID:30026316
      reference_title: Biallelic RIPK1 mutations in humans cause severe immunodeficiency, arthritis, and intestinal inflammation.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        They had immunodeficiency with lymphopenia and altered production of various
        cytokines revealed by whole-blood assays.
      explanation: >-
        Names the assay and the abnormality it detects, in the patients.
  - target: Defective T and B Cell Differentiation
    relationship: PHARMACODYNAMIC_MARKER_OF
    endpoint_context: MONITORING
    interpretation: >-
      The cytokine production defect reversed after haematopoietic stem cell
      transplantation, so the assay tracks correction of the haematopoietic
      compartment rather than only confirming the diagnosis.
    evidence:
    - reference: PMID:30026316
      reference_title: Biallelic RIPK1 mutations in humans cause severe immunodeficiency, arthritis, and intestinal inflammation.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Hematopoietic stem cell transplantation reversed cytokine production defects
        and resolved clinical symptoms in one patient.
      explanation: >-
        The reversal, in one patient. A single observation, which is why the
        interpretation says tracks rather than validates.
  evidence:
  - reference: PMID:30026316
    reference_title: Biallelic RIPK1 mutations in humans cause severe immunodeficiency, arthritis, and intestinal inflammation.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      In vitro, RIPK1-deficient cells showed impaired mitogen-activated protein
      kinase activation and cytokine secretion and were prone to necroptosis.
    explanation: >-
      The cell-level counterpart of the whole-blood finding, measured in patient cells.
diagnosis:
- name: RIPK1 sequencing
  description: >-
    Molecular confirmation. Biallelic loss-of-function variants are the diagnosis, and
    the zygosity is not incidental detail: a heterozygous RIPK1 variant at the
    caspase-8 cleavage site Asp324 indicates a different, dominantly inherited
    hyperinflammatory disease rather than a milder form of this one, so a report that
    stops at "RIPK1 variant found" is not a diagnosis.
  evidence:
  - reference: PMID:30591564
    reference_title: Human RIPK1 deficiency causes combined immunodeficiency and inflammatory bowel diseases.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Here, we report on eight patients from six unrelated pedigrees with biallelic
      loss-of-function mutations in RIPK1 presenting with primary immunodeficiency
      and/or intestinal inflammation.
    explanation: >-
      The genotype that defines the disease, with the biallelic requirement explicit.
  - reference: PMID:34163478
    reference_title: RIPK1-Associated Inborn Errors of Innate Immunity.
    supports: SUPPORT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    snippet: >-
      This review discusses the molecular pathogenesis of RIPK1-deficiency and
      cleavage-resistant RIPK1 induced autoinflammatory (CRIA) disorders and
      summarizes the clinical manifestations of respective diseases to help with the
      identification of new patients.
    explanation: >-
      Places the two RIPK1 diseases side by side, which is what makes reading the
      zygosity part of the diagnostic step rather than an afterthought.
- name: Whole-blood cytokine production assay
  description: >-
    The functional test. Whole-blood stimulation assays revealed altered production of
    various cytokines in the founding patients, and the same measurement normalised
    after transplantation. It is accessible in a way the cell-level work is not.
  markers: >-
    Multiple cytokines on whole-blood stimulation; the entry's biochemical section
    carries this as a readout of the signalling node.
  evidence:
  - reference: PMID:30026316
    reference_title: Biallelic RIPK1 mutations in humans cause severe immunodeficiency, arthritis, and intestinal inflammation.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      They had immunodeficiency with lymphopenia and altered production of various
      cytokines revealed by whole-blood assays.
    explanation: The assay and its abnormal result in the founding cohort.
- name: Lymphocyte count
  description: >-
    Lymphopenia is the other laboratory feature named in the disease definition and is
    the cheapest abnormality to detect, though it is not specific to this disease.
  evidence:
  - reference: PMID:30026316
    reference_title: Biallelic RIPK1 mutations in humans cause severe immunodeficiency, arthritis, and intestinal inflammation.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      They had immunodeficiency with lymphopenia and altered production of various
      cytokines revealed by whole-blood assays.
    explanation: Lymphopenia in the founding cohort.
genetic:
- name: RIPK1
  gene_term:
    preferred_term: RIPK1
    term:
      id: hgnc:10019
      label: RIPK1
  relationship_type: CAUSATIVE
  notes: >-
    Receptor-interacting serine/threonine kinase 1, on chromosome 6p25.2. Biallelic
    loss-of-function variants cause this disease. Heterozygous variants at the
    caspase-8 cleavage site Asp324 cause a different, dominantly inherited
    hyperinflammatory disease, so the same gene supports two diseases distinguished
    by zygosity and by the direction of the functional consequence. That second
    disease is not curated here and should not be folded into this entry.
  evidence:
  - reference: PMID:30026316
    reference_title: Biallelic RIPK1 mutations in humans cause severe immunodeficiency, arthritis, and intestinal inflammation.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      RIPK1 (receptor-interacting serine/threonine kinase 1) is a master regulator of
      signaling pathways leading to inflammation and cell death and is of medical
      interest as a drug target.
    explanation: >-
      Identifies the gene product and its dual role in inflammation and cell death.
  - reference: PMID:34163478
    reference_title: RIPK1-Associated Inborn Errors of Innate Immunity.
    supports: SUPPORT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    snippet: >-
      This review discusses the molecular pathogenesis of RIPK1-deficiency and
      cleavage-resistant RIPK1 induced autoinflammatory (CRIA) disorders and
      summarizes the clinical manifestations of respective diseases to help with the
      identification of new patients.
    explanation: >-
      Sets the two RIPK1 diseases side by side, which is the basis for the warning in
      this entry's notes against conflating them.
treatments:
- name: Haematopoietic Stem Cell Transplantation
  description: >-
    Transplantation reversed the cytokine production defect and resolved clinical
    symptoms in one reported patient. Because RIPK1 is expressed well beyond the
    haematopoietic compartment, the fact that replacing that compartment alone was
    sufficient is itself a mechanistic result and not only a therapeutic one. The
    evidence base is a single patient.
  therapeutic_modality: CELL_THERAPY
  treatment_term:
    preferred_term: haematopoietic stem cell transplantation
    term:
      id: NCIT:C15431
      label: Hematopoietic Cell Transplantation
  target_mechanisms:
  - target: Defective T and B Cell Differentiation
    description: >-
      Replacing the haematopoietic compartment supplies lymphoid progenitors with
      intact RIPK1.
    evidence:
    - reference: PMID:30026316
      reference_title: Biallelic RIPK1 mutations in humans cause severe immunodeficiency, arthritis, and intestinal inflammation.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Hematopoietic stem cell transplantation reversed cytokine production defects
        and resolved clinical symptoms in one patient.
      explanation: >-
        The rescue, in a patient. It is one patient, which is why this entry does not
        state transplantation as established therapy.
  evidence:
  - reference: PMID:30026316
    reference_title: Biallelic RIPK1 mutations in humans cause severe immunodeficiency, arthritis, and intestinal inflammation.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Hematopoietic stem cell transplantation reversed cytokine production defects
      and resolved clinical symptoms in one patient.
    explanation: The single reported transplant outcome.
  - reference: PMID:34163478
    reference_title: RIPK1-Associated Inborn Errors of Innate Immunity.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      HSCT has resolved the inflammatory manifestations and reduced the frequency of
      infections in one RIPK1-deficient patient
    explanation: >-
      The review's independent statement of the same single-patient result, which is
      useful because it names what transplantation resolved (the inflammatory
      manifestations and the infection frequency) rather than only that symptoms
      resolved.
    quote_role: REVIEW_SYNTHESIS
  - reference: PMID:34163478
    reference_title: RIPK1-Associated Inborn Errors of Innate Immunity.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      | family 1 | P2 | Pakistan | M | 867_870delTTTA | Y289* | 1 mo. | RLRR | Y | N | N
      | Y | N | N | N | N | severe RSV bronchiolitis, RI | HSCT | Alive |
    explanation: >-
      Table 1, patient P2: transplanted and alive. Four of the fourteen recessive
      patients were transplanted (P1, P2, P3 and P7) and three of those four died, which
      is the counterweight to the single published success and the reason this entry
      does not present transplantation as established therapy.
    quote_role: REVIEW_SYNTHESIS
- name: Immunoglobulin replacement
  description: >-
    Intravenous immunoglobulin is recorded for two of the fourteen recessive patients in
    the review's Table 1 (P4 and P14). It replaces the antibody output the B cell
    differentiation defect removes and is supportive rather than disease-directed: it
    does nothing about the autoinflammatory arm, and P14 died while receiving it.
  therapeutic_modality: PROTEIN_REPLACEMENT
  treatment_term:
    preferred_term: immunoglobulin therapy
    term:
      id: NCIT:C62710
      label: Immunoglobulin Therapy
  evidence:
  - reference: PMID:34163478
    reference_title: RIPK1-Associated Inborn Errors of Innate Immunity.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      | family 3 | P4 | Arab | F | 460-133_689-244del | DELexon5 | 2 yrs. | LLLL | Y | N
      | N | Y | N | N | N | N | severe RSV bronchiolitis, recurrent OM | IVIG | Alive |
    explanation: >-
      Table 1, patient P4: the `Treatments` column reads IVIG. The table legend expands
      the abbreviation.
    quote_role: REVIEW_SYNTHESIS
  - reference: PMID:34163478
    reference_title: RIPK1-Associated Inborn Errors of Innate Immunity.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      Ab, antibiotics; AF, antifungal; AZA, azathioprine; CS, corticosteroids; IBD,
      inflammatory bowel disease; IFX, infliximab; IVIG, intravenous immunoglobulin
    explanation: >-
      The legend that makes the treatment abbreviations in Table 1 readable, and the
      reason the rows quoted across this section can be interpreted at all.
    quote_role: REVIEW_SYNTHESIS
- name: Systemic corticosteroid therapy
  description: >-
    Corticosteroids are recorded for four of the fourteen recessive patients (P5, P7, P9
    and P12) in the review's Table 1, used against the inflammatory manifestations. No
    outcome is attributed to them in the table, and two of the four patients who
    received them died, so this records practice rather than efficacy.
  therapeutic_modality: SMALL_MOLECULE
  treatment_term:
    preferred_term: systemic corticosteroid therapy
    term:
      id: NCIT:C122080
      label: Systemic Corticosteroid Therapy
  evidence:
  - reference: PMID:34163478
    reference_title: RIPK1-Associated Inborn Errors of Innate Immunity.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      | family 9 | P12 | North Africa | F | 1802G>A | C601Y | 3 mos. | LLLL | Y | N | N
      | N | N | N | N | Y | OM, tetany, perianal disease | Ab, AF, CS | Alive |
    explanation: >-
      Table 1, patient P12: the `Treatments` column reads Ab, AF, CS, where CS is
      corticosteroids in the table legend.
    quote_role: REVIEW_SYNTHESIS
- name: Azathioprine
  description: >-
    Two of the fourteen recessive patients (P5 and P9) received azathioprine together
    with infliximab, antibiotics and corticosteroids, which is conventional inflammatory
    bowel disease management rather than anything specific to RIPK1. P5 died; P9 was
    alive at the time of writing. Azathioprine and infliximab are curated as separate
    treatments because their modalities differ and the slot takes one value, not because
    the source separates them.
  therapeutic_modality: SMALL_MOLECULE
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: azathioprine
      term:
        id: NCIT:C290
        label: Azathioprine
  evidence:
  - reference: PMID:34163478
    reference_title: RIPK1-Associated Inborn Errors of Innate Immunity.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      | family 4 | P5 | Caucasian | M | 1844T>C | I615T | 6 mos. | LLLR | Y | Y | Y | N
      | Y | N | N | Y | sepsis, esophagitis, gastritis, perianal disease | Ab, AZA, CS,
      IFX | Died |
    explanation: >-
      Table 1, patient P5: the `Treatments` column reads Ab, AZA, CS, IFX, which the
      legend expands to antibiotics, azathioprine, corticosteroids and infliximab.
    quote_role: REVIEW_SYNTHESIS
  - reference: PMID:34163478
    reference_title: RIPK1-Associated Inborn Errors of Innate Immunity.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      | family 8 | P9 | Arab | F | 1934C>T | T645M | 1 day | n.r. | Y | N | N | Y | Y |
      N | N | Y | OM, esophagitis, UTI, perianal disease | Ab, AZA, CS, IFX | Alive |
    explanation: >-
      Patient P9, the second patient on the same four-agent combination, and the one who
      survived it.
    quote_role: REVIEW_SYNTHESIS
- name: Infliximab
  description: >-
    Given with azathioprine to the same two patients. Infliximab blocks TNF, and using
    it in a disease whose lesion already blunts TNFR1-to-NF-kappaB signalling is a
    mechanistic oddity that no located source comments on. That is recorded rather than
    resolved: nothing here supports saying whether the drug helps, harms, or reaches the
    autoinflammatory arm by some route the signalling defect leaves intact.
  therapeutic_modality: MONOCLONAL_ANTIBODY
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: infliximab
      term:
        id: NCIT:C1789
        label: Infliximab
  evidence:
  - reference: PMID:34163478
    reference_title: RIPK1-Associated Inborn Errors of Innate Immunity.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      | family 4 | P5 | Caucasian | M | 1844T>C | I615T | 6 mos. | LLLR | Y | Y | Y | N
      | Y | N | N | Y | sepsis, esophagitis, gastritis, perianal disease | Ab, AZA, CS,
      IFX | Died |
    explanation: >-
      Table 1, patient P5: the `Treatments` column reads Ab, AZA, CS, IFX, which the
      legend expands to antibiotics, azathioprine, corticosteroids and infliximab.
    quote_role: REVIEW_SYNTHESIS
  - reference: PMID:34163478
    reference_title: RIPK1-Associated Inborn Errors of Innate Immunity.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      | family 8 | P9 | Arab | F | 1934C>T | T645M | 1 day | n.r. | Y | N | N | Y | Y |
      N | N | Y | OM, esophagitis, UTI, perianal disease | Ab, AZA, CS, IFX | Alive |
    explanation: >-
      Patient P9, the second patient on the same four-agent combination, and the one who
      survived it.
    quote_role: REVIEW_SYNTHESIS
- name: Antibiotic therapy
  description: >-
    Antibiotics are the most frequently recorded treatment in the review's Table 1, in
    seven of fourteen recessive patients (P5, P6, P9, P10, P11, P12 and P14). Given a
    cohort whose commonest manifestations are pneumonia, otitis media and perianal
    disease, this is treatment of the infection burden rather than prophylaxis; the
    table does not distinguish the two.
  therapeutic_modality: SMALL_MOLECULE
  treatment_term:
    preferred_term: antibiotic therapy
    term:
      id: NCIT:C15620
      label: Antibiotic Therapy
  evidence:
  - reference: PMID:34163478
    reference_title: RIPK1-Associated Inborn Errors of Innate Immunity.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      | family 9 | P10 | North Africa | M | 1802G>A | C601Y | 6 mos. | LLRL | Y | N | N
      | N | Y | N | N | Y | OM, perianal disease, omphalitis | Ab, AF | Alive |
    explanation: >-
      Table 1, patient P10: the `Treatments` column reads Ab, AF. The same row records
      otitis media, perianal disease and omphalitis, which is the burden being treated.
    quote_role: REVIEW_SYNTHESIS
- name: Antifungal therapy
  description: >-
    Antifungals are recorded for the three affected siblings of family 9 (P10, P11 and
    P12) in the review's Table 1, and for no one else. A treatment confined to one
    family is as likely to reflect that centre's practice as the disease, which is why
    it is recorded without a frequency claim.
  therapeutic_modality: SMALL_MOLECULE
  treatment_term:
    preferred_term: antifungal therapy
    term:
      id: NCIT:C15704
      label: Antifungal Therapy
  evidence:
  - reference: PMID:34163478
    reference_title: RIPK1-Associated Inborn Errors of Innate Immunity.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      | family 9 | P11 | North Africa | M | 1802G>A | C601Y | 20 days | LLLL | Y | N | N
      | N | Y | N | N | Y | OM, tetany, perianal disease | Ab, AF | Alive |
    explanation: >-
      Table 1, patient P11: the `Treatments` column reads Ab, AF, where AF is antifungal
      in the legend.
    quote_role: REVIEW_SYNTHESIS
- name: Interleukin-1 inhibition
  description: >-
    Proposed, not reported. The review argues that IL-1 inhibitors may help the
    inflammatory manifestations, which follows directly from the raised IL-1 beta output
    on the inflammasome node, and no patient in its own table received one. It is
    recorded here as a mechanistically motivated proposal so that the pathograph and the
    therapeutic suggestion stay attached; the specific agent is not named by the source,
    so none is bound.
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
  evidence:
  - reference: PMID:34163478
    reference_title: RIPK1-Associated Inborn Errors of Innate Immunity.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      In patients with RIPK1 deficiency, treatment with IL-1 inhibitors may ameliorate
      the inflammatory manifestations.
    explanation: >-
      The proposal, in the review's own words. It is a suggestion in a discussion
      section, with no trial, no case report and no patient behind it, and the treatment
      description says so.
    quote_role: REVIEW_SYNTHESIS
  target_mechanisms:
  - target: Increased Inflammasome Activity
    description: >-
      The proposal targets this node specifically: the inflammatory arm is attributed to
      NLRP3 activation with high IL-1 beta output, and blocking IL-1 is the direct
      countermeasure to that output. It would leave the signalling-loss arm untouched.
    evidence:
    - reference: PMID:34163478
      reference_title: RIPK1-Associated Inborn Errors of Innate Immunity.
      supports: SUPPORT
      evidence_source: OTHER
      snippet: >-
        In patients with RIPK1 deficiency, treatment with IL-1 inhibitors may ameliorate
        the inflammatory manifestations.
      explanation: >-
        The same sentence, quoted here for the mechanism the proposal acts on rather
        than for the proposal itself.
      quote_role: REVIEW_SYNTHESIS
discussions:
- discussion_id: ripk1_neurodevelopmental_features
  kind: KNOWLEDGE_GAP
  prompt: >-
    Are the motor delay and intellectual disability reported in one patient part of
    RIPK1 deficiency, or incidental to it?
  attaches_to:
  - phenotypes#Motor delay
  - phenotypes#Mild intellectual disability
  rationale: >-
    Both features come from a single case report whose authors say explicitly that they
    had not previously been associated with the disease. One patient is not a phenotype,
    and in a disorder presenting with severe infection and chronic enteropathy in the
    first year of life, developmental delay has several ordinary explanations that have
    nothing to do with RIPK1: hypoxia, malnutrition, prolonged hospitalisation, or the
    consanguinity that produced the homozygous variant also producing a second one. The
    fourteen-patient series records no neurological feature at all, which is weak
    evidence against but is not nothing. Nothing in this entry's pathograph reaches
    either phenotype and nothing should until a second patient is reported.
- discussion_id: ripk1_extraintestinal_features
  kind: KNOWLEDGE_GAP
  prompt: >-
    What produces the upper gastrointestinal, perianal and hepatosplenic features of
    RIPK1 deficiency, none of which the located mechanism reaches?
  attaches_to:
  - phenotypes#Gastritis
  - phenotypes#Esophagitis
  - phenotypes#Perianal disease
  - phenotypes#Hepatomegaly
  - phenotypes#Splenomegaly
  rationale: >-
    The entry's pathograph explains the disease through two arms: lost NF-kappaB and
    MAPK signalling producing the lymphocyte differentiation defect, and necroptosis
    plus inflammasome activity producing intestinal inflammation. The located
    mechanistic work places the cell-death defect specifically in intestinal epithelial
    cells. But the largest clinical series records esophagitis in four patients,
    gastritis in three, perianal disease in eight and hepatosplenomegaly in four, and
    none of those sites is intestinal epithelium. Gastritis was previously drawn as a
    DIRECT consequence of the intestinal epithelial node, which contradicted this
    rationale and was wrong for the same reason an esophagitis edge would have been: the
    node binds intestinal epithelial cell, and the stomach is not that cell type. That
    edge is removed and the phenotype sits in this gap with its siblings. Either the epithelial death defect is
    not confined to the intestine, or a second mechanism is operating, or some of these
    are complications of treatment and of the infection burden rather than of the
    disease. The table cannot distinguish those, and no located source addresses it, so
    the phenotypes are recorded with no incoming edge rather than attached to the
    nearest plausible node.
- discussion_id: ripk1_inflammasome_route
  kind: KNOWLEDGE_GAP
  prompt: >-
    By what route does loss of RIPK1 increase inflammasome activity, when the same
    loss reduces NF-kappaB signalling?
  attaches_to:
  - pathophysiology#Increased Inflammasome Activity
  rationale: >-
    This is the hinge of the disease. RIPK1 deficiency lowers one inflammatory output
    and raises another in the same patient, and an account of the disease that does
    not explain the second is incomplete. A non-canonical TLR4-TRIF-RIPK1-FADD-caspase-8
    axis has been proposed in review, but no located primary source demonstrates it in
    RIPK1-deficient human cells, so the causal edge in this entry is typed with unknown
    intermediates rather than as a mechanism.
- discussion_id: ripk1_arthritis_driver
  kind: KNOWLEDGE_GAP
  prompt: >-
    Is the progressive polyarthritis driven by the autoinflammatory arm, by the
    infection burden, or by both?
  attaches_to:
  - phenotypes#Arthritis
  rationale: >-
    The arthritis is attached to the inflammasome node in this entry because it is the
    autoinflammatory feature, but no located source establishes that. A patient with
    recurrent infections and a chronically inflamed gut has other routes to synovitis,
    and distinguishing them would change whether joint disease is expected to respond
    to correcting the haematopoietic compartment.
notes: >-
  Two things are worth keeping straight about this entry. The first is that RIPK1
  carries two named diseases, and they are not variants of one severity spectrum:
  biallelic loss of function gives this disease, while heterozygous variants that
  block caspase-8 cleavage at Asp324 give cleavage-resistant RIPK1-induced
  autoinflammatory syndrome, in which signalling is amplified rather than lost. An
  entry that treated them as one would have to assert two opposite functional
  consequences of the same gene.

  The second is the shape of the evidence. Almost every claim here rests on two
  patient series, and the mechanistic measurements in both were made in patient
  cells rather than in a model system, which is unusually favourable. What is thin
  is anything quantitative: no source located for this entry gives a frequency for
  any individual phenotype, a prevalence, or a natural history beyond the
  presentation. Frequency bands here are therefore reasoned from presence across the
  reported cohorts and say so in each phenotype's description, rather than being
  transcribed from a published denominator that does not exist.

  No GeneReviews chapter exists for this disease. `just check-genereviews` reports
  NO_CHAPTER against the committed Bookshelf index.
references:
- reference: PMID:30026316
  title: Biallelic RIPK1 mutations in humans cause severe immunodeficiency, arthritis, and intestinal inflammation.
- reference: PMID:30591564
  title: Human RIPK1 deficiency causes combined immunodeficiency and inflammatory bowel diseases.
- reference: PMID:31213653
  title: Primary immunodeficiency with chronic enteropathy and developmental delay in a boy arising from a novel homozygous RIPK1 variant.
- reference: PMID:34163478
  title: RIPK1-Associated Inborn Errors of Innate Immunity.
📚

References & Deep Research

References

4
PMID:30026316
Biallelic RIPK1 mutations in humans cause severe immunodeficiency, arthritis, and intestinal inflammation.
No top-level findings curated for this source.
PMID:30591564
Human RIPK1 deficiency causes combined immunodeficiency and inflammatory bowel diseases.
No top-level findings curated for this source.
PMID:31213653
Primary immunodeficiency with chronic enteropathy and developmental delay in a boy arising from a novel homozygous RIPK1 variant.
No top-level findings curated for this source.
PMID:34163478
RIPK1-Associated Inborn Errors of Innate Immunity.
No top-level findings curated for this source.

Deep Research

1

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

Evaluations and curation notes (1)

Create: Immunodeficiency 57 (RIPK1 deficiency) · 2026-09-17T14:38:11Z · View source

De-novo curation of immunodeficiency 57 (MONDO:0020849), biallelic RIPK1 loss of function, from a Perplexity sonar-deep-research run (research/Immunodeficiency_57-deep-research-perplexity.md, 366s, 19 citations). The report was used as a lead only. Two things made it unusable as a citation source directly. Its .citations.md sidecar lists web URLs (OMIM, MalaCards, PanelApp, ZFIN, publisher pages) rather than PMIDs, and only three PMID strings appear anywhere in the body, so the report's own reference-validation block (7 checked, 7 resolved) covers a small minority of its actual sourcing. Its ontology suggestions were worse: the run's Term Validation section records 9 of 37 named terms resolving to a different term than the report calls them, including HP:0002597 offered as 'Inflammatory bowel disease' (HPO: Abnormality of the vasculature) and HP:0012404 offered as 'Early-onset inflammatory bowel disease' (HPO: Abnormal urine citrate concentration), plus HP:0003479 which does not exist. No CURIE was taken from the report. Every term in this entry was looked up against OLS in the same step it was written, and hgnc:10019 was read from the repository's own cache/hgnc/terms.csv. References were sourced independently via PubMed esearch and cached with just fetch-reference: PMID:30026316 (Cuchet-Lourenco, Science 2018, founding cohort), PMID:30591564 (Li, PNAS 2019, second series), PMID:31213653 (Uchiyama, single case adding motor and cognitive delay), PMID:34163478 (Zhang/Aksentijevich review, domain architecture and the CRIA contrast). Curation judgements worth recording. The inflammasome edge is typed INDIRECT_UNKNOWN_INTERMEDIATES rather than DIRECT: the cited sentence establishes that inflammasome activity rises but says nothing about the route, and the proposed non-canonical TLR4-TRIF-RIPK1-FADD-caspase-8 axis appears only in review, so it is recorded as a KNOWLEDGE_GAP discussion instead of asserted. The arthritis edge is typed the same way for the same reason and carries its own gap. 'Motor and cognitive delay' is left without an HP binding because the single source names two distinct features in one sentence and binding either alone would misrepresent it. No frequency in this entry comes from a published denominator, because none exists for this disease; each band states in its own description what it is reasoned from. Validation: just validate passed; 28/28 snippets verified against cached references; just validate-terms passed; check-entity-refs, check-causal-targets, check-duplicate-keys and check-qualifier-terms all OK; 6 of 7 phenotypes causally connected (85.7%). just check-genereviews reports NO_CHAPTER, which the entry's notes record.

Perplexity ▸
1. Disease Information
sonar-deep-research 19 citations 2026-09-17T14:24:28.885784

1. Disease Information

1.1 Overview and Core Definition

Immunodeficiency 57 with autoinflammation (IMD57) is defined as a primary immunodeficiency characterized by recurrent infections starting in the first year of life, lymphopenia, altered production of multiple cytokines, inflammatory polyarthritis, and chronic active inflammation of the digestive tract, caused by homozygous or compound heterozygous loss-of-function mutations in the RIPK1 gene on chromosome 6p25.2.[1][5][11][14][18] ZFIN and Disease Ontology describe IMD57 as “immune dysregulation–inflammatory bowel disease–arthritis–recurrent infections–lymphopenia syndrome,” emphasizing the combined immunodeficiency and autoinflammatory phenotype.[1] MalaCards similarly summarizes the disease as “a rare genetic immune disease characterized by early onset of recurrent bacterial, viral, and fungal infections, chronic inflammatory bowel disease, gastritis, and inflammatory polyarthritis.”[5] The first detailed human description came from Cuchet-Lourenço et al. in Science in 2018, who reported four patients from three unrelated consanguineous families with complete RIPK1 deficiency due to homozygous mutations, presenting with severe infections, early-onset inflammatory bowel disease (IBD), and progressive polyarthritis.[18]

ClinGen’s Primary Immune Regulatory Disorders Gene Curation Expert Panel (GCEP) has classified the RIPK1–IMD57 gene–disease relationship as “definitive,” noting that at least 11 distinct variants (missense, nonsense, frameshift, and large deletions) have been identified in 13 probands across five independent publications, all with consistent clinical phenotypes.[3] The panel emphasizes that all reported patients present with recurrent infections and early-onset IBD, and that the mechanism of pathogenicity is loss of function of RIPK1.[3] In a 2021 review, Liu et al. (Frontiers in Immunology) grouped IMD57 under “RIPK1-associated inborn errors of innate immunity,” together with a distinct autosomal dominant autoinflammatory condition caused by cleavage-resistant RIPK1 mutations, highlighting the dual roles of RIPK1 in immune defense and immune regulation.[12]

From a disease classification standpoint, IMD57 fits squarely within the category of Mendelian primary immunodeficiency / primary immune regulatory disorders, with features that overlap combined immunodeficiency, monogenic IBD, and systemic autoinflammatory disease.[3][5][10][12] It is distinguished clinically by the triad of severe early-onset IBD, progressive inflammatory arthritis, and recurrent severe infections, all in the setting of lymphopenia and dysregulated cytokine responses.[3][5][11][18] The point prevalence is estimated to be less than 1 per 1,000,000 worldwide, consistent with its status as an ultra-rare disorder.[5]

1.2 Key Identifiers and Ontology Mapping

Multiple biomedical databases now index Immunodeficiency 57 with consistent identifiers and cross-references. OMIM designates IMD57 as “Immunodeficiency 57 with autoinflammation” with the phenotype MIM number 618108, linked to the RIPK1 gene (MIM 603453) and locus 6p25.2.[11][14] Orphanet lists the corresponding Orpha number 529977 for this condition, and Disease Ontology assigns DOID:0111952.[1][11] MONDO, the Mondo Disease Ontology, references IMD57 under MONDO:0020849, as noted in ClinGen’s gene–disease curation.[3] ZFIN explicitly maps the human disease entry “immunodeficiency 57” to DO:0111952 and provides cross-links to OMIM and Orphanet.[1]

The RIPK1 gene itself is catalogued under HGNC-approved symbol RIPK1, OMIM gene entry 603453, and cytogenetic location 6p25.2, with GRCh38 genomic coordinates 6:3,063,967–3,115,187.[14] OMIM lists two phenotypes linked to RIPK1: (1) Autoinflammation with episodic fever and lymphadenopathy (AIEFL; MIM 618852), an autosomal dominant condition caused by heterozygous cleavage-resistant mutations; and (2) Immunodeficiency 57 with autoinflammation (IMD57; MIM 618108), an autosomal recessive condition caused by biallelic loss-of-function mutations.[14][19] This dual mapping underscores the allelic heterogeneity and functional bifurcation of RIPK1-associated human disease.

In terms of controlled vocabularies, IMD57 can be mapped to Human Phenotype Ontology (HPO) terms including early-onset inflammatory bowel disease (HP:0012404), recurrent respiratory infections (HP:0002205), recurrent bacterial infections (HP:0002718), lymphopenia (HP:0001888), inflammatory arthritis (HP:0003481), failure to thrive (HP:0001508), hepatosplenomegaly (HP:0001433), and hypogammaglobulinemia (HP:0004313), among others.[3][5][11][18] At the disease level, the condition aligns with MONDO:0020849 (immunodeficiency 57), which integrates OMIM, Orphanet, and other ontology sources.[3]

1.3 Synonyms and Alternative Names

Several synonymous or related names are used for Immunodeficiency 57 in the literature and databases. OMIM and multiple resources refer to it as “Immunodeficiency 57 with autoinflammation” and often abbreviate this as IMD57.[11][14][18] ZFIN and Disease Ontology describe a longer descriptive synonym: “immune dysregulation–inflammatory bowel disease–arthritis–recurrent infections–lymphopenia syndrome,” capturing the cardinal clinical manifestations.[1] MalaCards lists additional synonyms, including “Immune Dysregulation-Inflammatory Bowel Disease-Arthritis-Recurrent Infections-Lymphopenia Syndrome” and “Immunodeficiency 57 with Autoinflammation.”[5]

Genomics England’s PanelApp entries for both autoinflammatory disorders and infantile enterocolitis / monogenic inflammatory bowel disease panels list the RIPK1-associated phenotype as “Immunodeficiency 57, OMIM:618108” or “Immunodeficiency 57 with autoinflammation,” and explicitly distinguish it from “Autoinflammation with episodic fever and lymphadenopathy, OMIM:618852.”[8][9][10] ClinGen refers to the condition consistently as “immunodeficiency 57” with MONDO:0020849 and emphasizes its classification as a primary immune regulatory disorder.[3]

Thus, in developing a disease knowledge base entry, the primary name should be “Immunodeficiency 57 with autoinflammation (IMD57)”, with synonyms including “immune dysregulation–inflammatory bowel disease–arthritis–recurrent infections–lymphopenia syndrome” and “RIPK1 deficiency.”[1][3][5][11][18] The term “RIPK1 deficiency” is particularly useful mechanistically, but it should be reserved for biallelic loss-of-function conditions to avoid confusion with the distinct heterozygous cleavage-resistant RIPK1 autoinflammatory syndrome.[12][14][19]

1.4 Data Sources and Evidence Types

The current understanding of IMD57 is derived primarily from aggregated disease-level resources and a small number of detailed case series and mechanistic studies, rather than from large clinical cohorts or electronic health record–based analyses. OMIM, Orphanet, MalaCards, ClinGen, ZFIN, and PanelApp provide consolidated descriptions that integrate findings from the original case reports and mechanistic studies.[1][3][5][10][11][14][18]

The foundational clinical evidence comes from human case reports and series, including the seminal Science article by Cuchet-Lourenço et al. (2018; PMID: 30026316), Li et al. (2019; PMID: 30591564), Uchiyama et al. (2019; PMID: 31213653), and later case descriptions compiled in ClinGen and Frontiers reviews.[3][12][18] These human data are complemented by extensive mouse genetic models of Ripk1 deficiency or mutation, which revealed perinatal lethality with severe immune abnormalities, profound sensitivity to necroptosis and apoptosis, and critical roles in TNF, TLR, and interferon receptor signaling.[13][16][17]

In vitro studies using patient-derived cells and engineered systems further demonstrate the molecular consequences of RIPK1 deficiency, including defective MAPK activation, impaired production of cytokines such as IL-6, IL-10, TNF-α, and IL-12, and enhanced necroptosis; these findings are summarized by Cuchet-Lourenço et al. and by ClinGen.[3][18] As ClinGen notes, “studies robustly show that RIPK1 is involved in MAPK p38 phosphorylation and subsequent stimulation of the production of IL-6, IL-10, TNF-α and IL-12; loss of RIPK1 also leads to excessive production of the proinflammatory cytokine IL-1β.”[3]

Therefore, IMD57 is a disease where multiple evidence streams converge: human clinical observation, human genetic data, in vitro functional assays, and animal models. There are currently no large-scale population-based studies, randomized trials, or registry data, reflecting the ultra-rare status of the condition and the recency of its recognition (first reports in 2018).[3][12][18]

2. Etiology

2.1 Primary Causal Factors: RIPK1 Loss-of-Function

The primary causal factor in Immunodeficiency 57 is biallelic loss-of-function (LoF) mutation in the RIPK1 gene, which encodes receptor-interacting serine/threonine-protein kinase 1, a key regulator of cell death and inflammatory signaling pathways.[3][12][14][15][18] OMIM, ClinGen, and MalaCards all indicate that IMD57 is “caused by mutations in the RIPK1 gene on chromosome 6p25.2” and that the mechanism of pathogenicity is loss of function.[3][5][11][14] Cuchet-Lourenço et al. identified homozygous LoF mutations (nonsense and frameshift) in four patients from three consanguineous families, demonstrating that complete absence of RIPK1 protein leads to severe immunodeficiency and autoinflammation.[18]

ClinGen’s curation summarizes that at least 11 variants in RIPK1 have been associated with IMD57, including four missense variants, four nonsense variants, one frameshift variant, and two large deletions, all in homozygous or compound heterozygous configuration in affected individuals.[3] These variants are distributed across the gene and include truncating mutations that abolish protein expression, as well as missense changes that severely disrupt functional domains.[3][12][14][18] Functional studies in patients’ cells and model systems show that these variants lead to absent or severely reduced RIPK1 protein and loss of both its kinase activity and scaffolding functions.[3][12][18]

RIPK1 is a multifunctional adaptor and kinase that integrates signals from multiple receptors, including TNF receptor 1 (TNFR1), Toll-like receptors (TLR3, TLR4), and RIG-I-like receptors, and regulates NF-κB activation, MAPK signaling, and cell death pathways (apoptosis and necroptosis).[13][15][16][17] As one review describes, “RIPK1 is a ‘Swiss Army knife’ of innate immune regulation” connected to TNFRs, TLRs, type I interferon receptor (IFNAR1), STING, and MAVS, and it controls transcription and translation of inflammatory genes as well as multiple forms of programmed cell death.[15] Complete loss-of-function of such a central hub understandably has profound consequences for immune homeostasis, leading to both immunodeficiency (due to defective survival and activation of immune cells) and autoinflammation (due to uncontrolled cell death and dysregulated cytokine production).[12][15][17][18]

Thus, IMD57 is best conceptualized as a monogenic primary immunodeficiency / immune dysregulation syndrome due to germline, biallelic, loss-of-function mutations in RIPK1, with no evidence to date that environmental or acquired factors alone can cause a similar phenotype in the absence of genetic defects in this gene.[3][5][12][18]

2.2 Genetic Risk Factors: Causal Variants and Susceptibility Context

From a risk-factor perspective, the presence of biallelic pathogenic RIPK1 variants is both necessary and sufficient for the IMD57 phenotype in reported families, consistent with monogenic Mendelian inheritance.[3][11][14][18] All described patients have either homozygous or compound heterozygous mutations in RIPK1, often in the context of parental consanguinity, and there is no suggestion of incomplete penetrance for classic LoF alleles.[3][18]

ClinGen catalogues at least 11 disease-associated alleles in 13 probands, including missense, nonsense, frameshift, and structural variants.[3] Cuchet-Lourenço et al. reported variants such as a homozygous frameshift leading to early truncation, while Li et al. and Uchiyama et al. described additional missense and truncating variants.[3][18] The allele frequency of these specific pathogenic variants in population databases such as gnomAD is extremely low or absent, consistent with their pathogenicity and the rarity of IMD57.[3][5] Although detailed allele frequencies are not provided in the sources summarized here, ClinGen notes that the variants are rare, often private to a single family, and that their functional impact has been demonstrated experimentally.[3]

Beyond the direct causal variants, there is currently no strong evidence for modifier genes or polygenic risk factors that modulate IMD57 susceptibility or severity, although this cannot be excluded given the small number of cases. Other genes in the linear ubiquitin chain assembly complex (LUBAC), such as RBCK1 and RNF31 (HOIP), and negative regulators such as OTULIN, can cause related immunodeficiency and autoinflammatory syndromes when mutated, but these represent distinct genetic disorders rather than modifiers of RIPK1-deficient IMD57.[12] For example, LUBAC deficiency due to RBCK1 or RNF31 mutations leads to severe immunodeficiency and recurrent fever with polyglucosan myopathy, and OTULIN mutations cause OTULIN-related autoinflammatory syndrome (ORAS, otulipenia), reflecting convergent pathways in linear ubiquitin signaling and NF-κB regulation.[12]

Thus, at present, the primary genetic risk factor for IMD57 is the inheritance of two pathogenic RIPK1 alleles in an autosomal recessive fashion, often facilitated by parental consanguinity, with no established role for other susceptibility loci.[3][11][14][18]

2.3 Environmental and Lifestyle Risk Factors

There is no evidence that environmental, lifestyle, or occupational exposures independently cause Immunodeficiency 57 in the absence of RIPK1 mutations. However, as with other primary immunodeficiencies, environmental factors influence disease expression and complication risk by modulating exposure to infectious agents and perhaps the severity of inflammatory stimuli.[5][12][18] Patients with IMD57 are susceptible to a wide range of bacterial, viral, and fungal infections, particularly involving the gastrointestinal tract and respiratory system, and the frequency and severity of these infections will naturally be shaped by local pathogen burden, sanitation, vaccination practices, and access to medical care.[5][18]

Recurrent infections themselves can exacerbate inflammatory bowel disease and arthritis, creating a vicious cycle in which environmental pathogen exposure interacts with the underlying genetic defect in RIPK1 to drive morbidity.[5][12][18] For example, in RIPK1-deficient mice, infection or exposure to inflammatory stimuli such as TNF or TLR ligands can precipitate lethal necroptosis and systemic inflammation, suggesting that environmental inflammatory cues can dramatically unmask or amplify the consequences of RIPK1 loss.[13][16][17] Similar mechanisms may operate in humans, although direct data in IMD57 patients are limited.

Lifestyle factors such as diet, smoking, and physical activity have not been systematically studied in IMD57, but by analogy with other forms of early-onset inflammatory bowel disease, dietary patterns, microbial exposures, and antibiotic use may modulate intestinal inflammation and microbiome composition, potentially influencing the severity of enterocolitis.[10][12][18] Nonetheless, these influences should be viewed as modifying factors rather than primary causes, with the underlying RIPK1 deficiency remaining the central determinant of disease.

2.4 Protective Factors and Potential Modifiers

Given the rarity of IMD57 and the small number of reported patients, protective factors—either genetic or environmental—have not been formally characterized. There are no known protective RIPK1 variants that mitigate disease in biallelic LoF carriers, nor is there evidence of “resilient” individuals with two clearly pathogenic RIPK1 alleles and no phenotype.[3][14][18] It is plausible that polymorphisms in parallel survival pathways, antioxidant defenses, or cytokine regulators could modulate disease severity, but such hypotheses remain speculative.

In terms of environmental or treatment-related protective factors, hematopoietic stem cell transplantation (HSCT) appears to be a potent “curative” intervention for at least some patients. Cuchet-Lourenço et al. reported that HSCT in one RIPK1-deficient patient “reversed cytokine production defects and resolved clinical symptoms,” demonstrating that reconstitution of the hematopoietic compartment with RIPK1-sufficient cells can restore immune function and control inflammation.[18] This suggests that HSCT acts as a protective factor against disease progression, though it is a therapeutic intervention rather than a naturally occurring modifier.

Standard supportive measures—such as prophylactic antimicrobials, immunoglobulin replacement, and nutritional support—undoubtedly reduce morbidity and mortality, but these have not been systematically studied specifically in IMD57.[5][18] Their benefits are inferred from broader primary immunodeficiency practice and the observed reduction of infection burden in case reports. There is no evidence that specific diets, probiotics, or environmental interventions have unique protective effects beyond general care for immunocompromised children.

2.5 Gene–Environment Interactions

Although comprehensive gene–environment interaction studies are lacking, the biological role of RIPK1 strongly implies that environmental stimuli—particularly infections and inflammatory signals—interact with the genetic defect to shape disease expression. RIPK1 is activated downstream of TNFR1, TLR3/4, RIG-I-like receptors, and type I/II interferon receptors in response to cytokines, pathogen-associated molecular patterns (PAMPs), and damage-associated molecular patterns (DAMPs).[13][15][17] In normal individuals, this signaling network balances NF-κB–mediated pro-survival and inflammatory gene expression with controlled activation of apoptosis or necroptosis when needed.[13][15][17]

In RIPK1-deficient cells, TNF, TLR, and interferon signals can no longer properly engage NF-κB and MAPK pathways, and instead they may trigger unrestrained caspase-8–dependent apoptosis or RIPK3-MLKL–dependent necroptosis, leading to cell death, release of DAMPs, and further inflammation.[13][16][17][18] This means that environmental exposures such as infections or endotoxin may produce exaggerated tissue damage and inflammatory responses in IMD57 patients compared with healthy individuals. As Kaiser et al. demonstrated in mice, RIPK1 suppresses innate immune necrosis and apoptosis during critical periods like parturition, showing that environmental inflammatory insults can be fatal when RIPK1 is absent.[13]

Thus, gene–environment interaction in IMD57 can be conceptualized as follows: the inherited RIPK1 LoF mutation creates a latent vulnerability in immune cells and tissues, and environmental inflammatory triggers such as infections, microbiota-derived signals, and cytokines unmask this vulnerability, driving episodes of severe infection, enterocolitis, and arthritis. This interaction is consistent with the clinical observation that IMD57 patients suffer recurrent infections and chronic inflammatory disease, yet there are no reported cases of similar disease among individuals without RIPK1 mutations despite comparable environmental exposures.[3][5][12][18]

3. Phenotypes

3.1 General Clinical Phenotype and Age of Onset

The phenotype of Immunodeficiency 57 is dominated by recurrent severe infections, early-onset inflammatory bowel disease, and progressive inflammatory arthritis, with additional features including lymphopenia, hypogammaglobulinemia, hepatosplenomegaly, chronic lung disease, and failure to thrive.[3][5][11][12][18] OMIM’s clinical synopsis describes “recurrent bacterial, viral, and fungal infections from infancy,” “lymphopenia,” “inflammatory bowel disease involving upper and lower gastrointestinal tract,” “inflammatory polyarthritis,” and “variable hypogammaglobulinemia.”[11] MalaCards emphasizes “diarrhea, vomiting, hepatosplenomegaly, mouth ulcers, perianal abscesses, chronic lung disease with bronchiectasis, and failure to thrive,” along with “skin rash associated with lymphocytic vasculitis.”[5]

The age of symptom onset is consistently in early infancy, often within the first year of life.[3][5][11][18] ClinGen notes that all patients “invariably present with recurrent infection and inflammatory bowel disease during early childhood,” and MalaCards lists onset in “infancy, neonatal” for the immune dysregulation–IBD–arthritis–recurrent infections–lymphopenia syndrome.[3][5] Thus, an appropriate HPO term is Neonatal onset (HP:0003623) or Infantile onset (HP:0003593), with Age of onset of gastrointestinal symptoms in infancy mapping to early-onset IBD (HP:0012404).

Symptom severity is generally severe or life-threatening without appropriate treatment. Patients experience life-threatening infections, severe malnutrition due to enterocolitis, and progressive joint damage from arthritis.[3][5][18] The disease course appears chronic and progressive, particularly for gastrointestinal and joint manifestations, although some patients may have fluctuating or episodic inflammatory activity superimposed on a chronic baseline.[3][5][12][18] There are currently too few patients to quantify symptom frequencies precisely, but ClinGen’s observation that all patients present with recurrent infection and IBD implies a frequency approaching 100% for these core features.[3]

The impact on quality of life is profound. Infants and children with IMD57 often require prolonged hospitalizations, parenteral nutrition, broad-spectrum antibiotics, immunosuppressive or biologic therapies, and in some cases HSCT.[5][18] Chronic pain and functional limitations from polyarthritis further impair daily activities, school attendance, and psychosocial development. While formal quality-of-life instruments (e.g., EQ-5D, SF-36) have not been applied in published reports, the constellation of severe immunodeficiency, chronic inflammation, and growth failure clearly corresponds to major reductions in physical, emotional, and social well-being.

3.2 Infectious Susceptibility and Immunologic Phenotypes

A hallmark of IMD57 is recurrent infections with bacteria, viruses, and fungi, reflecting a broad immunodeficiency rather than susceptibility to a single pathogen group.[3][5][11][12][18] Cuchet-Lourenço et al. reported that RIPK1-deficient patients experienced multiple episodes of pneumonia, severe bacterial infections, viral infections, and systemic fungal infection, often requiring intensive care and prolonged antimicrobial therapy.[18] ClinGen summarizes the phenotype as “recurrent bacterial, viral and fungal infections since early childhood.”[3] MalaCards similarly highlights “early onset of recurrent bacterial, viral, and fungal infections” as a defining characteristic.[5]

Immunologic evaluation reveals variable T-cell lymphopenia, with CD4 and CD8 T-cell counts often reduced, while B-cell and NK-cell counts may be normal or decreased.[3][5][18] ClinGen notes that “T-cell lymphopenia is typically observed, while B-cell and NK cell counts may be normal or decreased,” indicating a predominant but not exclusive T-cell defect.[3] Lymphopenia (HP:0001888) is therefore a core HPO term, with more specific mapping to reduced T-cell count (HP:0001883) and possibly combined immunodeficiency (HP:0005387). In some patients, hypogammaglobulinemia (HP:0004313) and impaired specific antibody responses are observed, suggesting defective B-cell help.[3][5][11][18]

Functional assays show altered cytokine production in response to TNF and TLR ligands, with reduced production of IL-6, IL-10, TNF-α, and IL-12, and paradoxically increased IL-1β, reflecting both impaired and dysregulated inflammation.[3][12][18] Cuchet-Lourenço et al. reported that “RIPK1-deficient cells showed impaired mitogen-activated protein kinase activation and cytokine secretion and were prone to necroptosis,” providing mechanistic insight into the immunologic phenotype.[18] ClinGen notes that studies “robustly show that RIPK1 is involved in MAPK p38 phosphorylation and subsequent stimulation of the production of IL-6, IL-10, TNF-α and IL-12; loss of RIPK1 also leads to excessive production of the proinflammatory cytokine IL-1β.”[3]

The quality-of-life impact of this infectious and immunologic phenotype is substantial. HPO terms capturing the phenotype include Recurrent bacterial infections (HP:0002718), Recurrent viral infections (HP:0004429), Recurrent fungal infections (HP:0002841), Recurrent lower respiratory tract infections (HP:0002110), and Chronic lung disease (HP:0006528), the latter particularly relevant in patients who develop bronchiectasis.[3][5][18] Frequent hospitalizations, intravenous antibiotics, and isolation measures restrict normal social interaction and schooling, while chronic lung disease can lead to long-term exercise intolerance and respiratory limitation.

3.3 Gastrointestinal Phenotypes: Early-onset Inflammatory Bowel Disease

The gastrointestinal phenotype in IMD57 is dominated by early-onset inflammatory bowel disease involving both small and large intestine and sometimes the upper gastrointestinal tract.[3][5][10][11][12][18] Patients present with chronic diarrhea, vomiting, abdominal pain, gastrointestinal bleeding, mouth ulcers, perianal disease, and failure to thrive, often mimicking severe very-early-onset IBD or infantile enterocolitis.[5][10][18] MalaCards notes that patients “exhibit early-onset inflammatory bowel disease involving the upper and lower gastrointestinal tract” and lists symptoms such as diarrhea, vomiting, perianal abscesses, and gastritis.[5] Genomics England’s “Infantile enterocolitis & monogenic inflammatory bowel disease” panel includes RIPK1 as a biallelic gene associated with IMD57, underscoring its role as a cause of monogenic IBD.[10]

Endoscopic and histologic findings in reported cases show chronic active inflammation with ulceration, crypt abscesses, and sometimes granulomas, consistent with severe IBD, though detailed pathology is not fully described in the summarized sources.[10][12][18] The HPO term Inflammatory bowel disease (HP:0002597) and more specific Early-onset inflammatory bowel disease (HP:0012404) are appropriate, along with Chronic diarrhea (HP:0002038), Gastrointestinal hemorrhage (HP:0002240), Mouth ulcers (oral ulcers; HP:0000155), and Perianal fistula or Perianal abscess (HP:0003403 / HP:0100640).[5][10][18]

The severity and chronicity of enterocolitis in IMD57 have profound consequences for growth and nutrition. Patients frequently display failure to thrive (HP:0001508), weight loss, and micronutrient deficiencies due to malabsorption and poor oral intake.[5][18] Some require parenteral nutrition or gastrostomy feeding, and the constant gastrointestinal symptoms markedly reduce appetite, energy, and participation in daily activities. From a quality-of-life perspective, chronic abdominal pain, frequent loose stools, and risk of incontinence can be particularly distressing for children and families.

3.4 Musculoskeletal and Autoinflammatory Phenotypes: Arthritis and Vasculitis

Another core feature of IMD57 is inflammatory polyarthritis, often progressive and disabling.[3][5][11][12][18] Cuchet-Lourenço et al. reported progressive polyarthritis affecting multiple joints, and ClinGen emphasizes that “all patients invariably present with recurrent infection and inflammatory bowel disease during early childhood” and “develop progressive polyarthritis.”[3][18] MalaCards similarly notes “inflammatory polyarthritis” and progression over time.[5] This phenotype likely corresponds to HPO terms Arthritis (HP:0001369), Inflammatory arthritis (HP:0003481), and Polyarthritis (HP:0003479), and in some cases Joint contracture (HP:0001371) if chronic inflammation leads to structural damage.

Skin involvement has also been described, including skin rash associated with lymphocytic vasculitis, suggesting small-vessel involvement as part of the autoinflammatory process.[5][12] MalaCards notes “skin rash associated with lymphocytic vasculitis,” and the Frontiers review mentions that one RIPK1-deficient patient had autoinflammatory manifestations beyond the classic triad, indicating that autoinflammation can extend to cutaneous and possibly systemic vasculitic features.[5][12] Appropriate HPO terms include Cutaneous vasculitis (HP:0002635), Skin rash (HP:0000988), and perhaps Leukocytoclastic vasculitis (HP:0002635) if histology is available.

These musculoskeletal and cutaneous manifestations significantly impair quality of life. Children with polyarthritis may experience chronic pain, morning stiffness, reduced range of motion, and difficulty walking or performing fine motor tasks, leading to limitations in play, schooling, and self-care. Skin vasculitis can cause painful lesions, ulceration, or cosmetic concerns, which may further affect psychosocial well-being. If unrecognized or inadequately treated, chronic joint inflammation can result in irreversible joint damage and disability.

3.5 Hematologic, Pulmonary, and Other Systemic Phenotypes

Beyond lymphopenia and hypogammaglobulinemia, IMD57 patients may exhibit hepatosplenomegaly, chronic lung disease with bronchiectasis, and other systemic features.[3][5][11][18] MalaCards lists hepatosplenomegaly, chronic lung disease with bronchiectasis, and failure to thrive among the common traits.[5] Hepatosplenomegaly likely reflects chronic immune activation, extramedullary hematopoiesis, or portal hypertension related to intestinal inflammation, and aligns with HPO term Hepatosplenomegaly (HP:0001433).[5][18] Chronic lung disease with bronchiectasis corresponds to Bronchiectasis (HP:0002110) and Chronic obstructive pulmonary disease or more broadly Chronic lung disease (HP:0006528).[5]

Laboratory abnormalities include lymphopenia, variable decreases in B and NK cells, and variable hypogammaglobulinemia, as noted above.[3][5][11][18] HPO terms such as Decreased T cell count (HP:0001883), Decreased B cell count (HP:0004322), Decreased NK cell count (HP:0012091), and Abnormal immunoglobulin level (HP:0004315) apply. Cytokine profiling in whole-blood assays reveals altered responses to TNF and TLR ligands, but these findings are usually reported in research settings rather than as routine diagnostics.[3][18]

The overall systemic phenotype is therefore one of multisystem immune dysregulation, affecting hematologic, gastrointestinal, musculoskeletal, pulmonary, and cutaneous systems. Quality-of-life impacts are cumulative: chronic fatigue, dyspnea from lung disease, abdominal pain, joint pain, and frequent hospitalizations create a heavy disease burden. Caregivers face substantial emotional and logistical challenges, and the risk of early mortality poses significant psychosocial stress on families.[3][5][18]

4. Genetic and Molecular Information

4.1 Causal Gene: RIPK1

The causal gene for Immunodeficiency 57 is RIPK1 (Receptor-interacting serine/threonine-protein kinase 1), also known as receptor-interacting protein kinase 1, encoded by the gene with OMIM entry 603453 and located on chromosome 6p25.2.[3][11][14][15] OMIM describes RIPK1 as a cytosolic protein kinase that controls multiple signaling pathways leading to inflammation and apoptotic or necroptotic cell death.[14] The gene spans approximately 51 kb in GRCh38 coordinates (6:3,063,967–3,115,187) and encodes a 671-amino acid protein with an N-terminal kinase domain, an intermediate region containing a RIP homotypic interaction motif (RHIM), and a C-terminal death domain.[14][15][17]

RIPK1 plays dual roles as a kinase and scaffold in pathways downstream of TNFR1, TLR3, TLR4, RIG-I-like receptors, and others.[13][15][17] In its scaffold role, RIPK1 helps assemble the TNFR1 complex I and other signaling complexes that activate NF-κB and MAPKs, promoting cell survival and inflammatory gene expression.[13][15][17] In its kinase role, RIPK1 can promote programmed cell death via formation of cytosolic complexes (often termed complex II, ripoptosome, or necrosome), which recruit caspase-8 to induce apoptosis or interact with RIPK3/MLKL to drive necroptosis.[13][15][16][17] These diverse functions are subject to extensive regulation by ubiquitination, phosphorylation, and caspase cleavage.[15][16][17]

In the context of human disease, the same gene underlies both autosomal dominant autoinflammation with episodic fever and lymphadenopathy (AIEFL; OMIM 618852) and autosomal recessive immunodeficiency 57 with autoinflammation (IMD57; OMIM 618108), depending on the nature and zygosity of the mutation.[14][19] AIEFL is caused by heterozygous missense mutations at the highly conserved residue Asp324 that render RIPK1 resistant to caspase-8 cleavage, resulting in cleavage-resistant hyperactive RIPK1 and recurrent autoinflammatory episodes.[12][14][19] In contrast, IMD57 is caused by biallelic LoF mutations that abolish RIPK1 expression or function, leading to a combined immunodeficiency and chronic autoinflammation.[3][12][14][18]

4.2 Pathogenic Variants and Variant Classes

ClinGen’s curation indicates that at least 11 distinct RIPK1 variants have been reported in IMD57 patients, including four missense variants, four nonsense variants, one frameshift, and two large deletions, all in homozygous or compound heterozygous state.[3] Cuchet-Lourenço et al. identified homozygous LoF mutations (including truncating variants) in four patients from three families; Li et al. and Uchiyama et al. subsequently reported additional variants.[3][18] Although the exact cDNA and protein-level nomenclature for all variants is not fully detailed in the sources summarized here, OMIM lists specific alleles (e.g., 603453.0001–603453.0003) corresponding to early reports.[14][18]

These variants share the common functional feature of loss-of-function, either through nonsense-mediated mRNA decay, truncated proteins lacking critical domains, or missense changes that abolish protein stability or disrupt essential functional motifs.[3][12][18] Functional studies in patient-derived fibroblasts or blood cells show absent or severely reduced RIPK1 protein by immunoblot, absent TNF-induced NF-κB activation, defective MAPK activation, and increased susceptibility to necroptosis.[3][12][18] Cuchet-Lourenço et al. concluded that “complete RIPK1 deficiency” was present in their patients and that this deficiency was sufficient to cause severe immunodeficiency and inflammatory disease.[18]

From a classification standpoint, these variants would be considered pathogenic or likely pathogenic under ACMG/AMP guidelines, based on criteria such as PVS1 (null variant in a gene where LoF is a known mechanism of disease), PS3 (well-established functional studies), PM2 (absent from controls), and PP4 (highly specific phenotype).[3] ClinVar and other variant databases catalog individual RIPK1 variants associated with IMD57, though detailed ClinVar entries are not explicitly summarized in the sources here.[10][14]

Because IMD57 is a germline congenital disorder, the variants are of germline origin, inherited from carrier parents in autosomal recessive fashion.[3][11][18] There is no evidence for somatic mosaicism or acquired somatic RIPK1 mutations contributing to this specific disease, although somatic modulation of RIPK1 activity may be relevant in other contexts such as cancer or inflammatory conditions.[15][17]

4.3 Functional Consequences and Mechanistic Classification

Functionally, the pathogenic RIPK1 variants in IMD57 share the mechanistic feature of loss-of-function, affecting both the kinase activity and scaffolding functions of the protein.[3][12][15][18] This contrasts sharply with the heterozygous Asp324 variants causing AIEFL/CRIA, which are cleavage-resistant gain-of-function mutants that make RIPK1 hyperactive and non-cleavable by caspase-8.[12][16][19]

Multiple lines of evidence support the LoF classification for IMD57 variants. Cuchet-Lourenço et al. demonstrated that patient cells lacked detectable RIPK1 protein, had impaired activation of MAPK p38 and ERK upon stimulation, and had blunted production of cytokines such as TNF-α and IL-6, indicating loss of normal pro-survival and inflammatory signaling.[18] At the same time, these cells were prone to necroptosis, suggesting that the protective scaffolding function of RIPK1, which normally suppresses uncontrolled RIPK3/MLKL activation, was absent.[18] Kaiser et al. and others showed in mice that RIPK1 deficiency leads to perinatal lethality due to uncontrolled necroptosis and apoptosis, further confirming the vital prosurvival role of RIPK1’s kinase-independent functions.[13][16]

RIPK1’s dual mechanistic roles have been encapsulated in reviews describing it as a “Swiss Army knife” of innate immune regulation.[15] In its scaffolding role in TNFR1 complex I, RIPK1 supports NF-κB activation and cell survival; in its kinase role, when deubiquitinated and released to cytosolic complexes, it can promote cell death via caspase-8 or RIPK3/MLKL.[13][15][17] Loss-of-function mutations that abolish both roles shift the balance toward unregulated cell death (due to absence of scaffolding) and impaired inflammatory gene expression (due to absence of NF-κB/MAPK activation), explaining the combination of immunodeficiency and autoinflammation in IMD57.[12][15][18]

At the level of Gene Ontology (GO), RIPK1 participates in biological processes such as TNF-mediated signaling pathway (GO:0033209), regulation of NF-kappaB transcription factor activity (GO:0032088), necroptotic process (GO:0070266), and apoptotic process (GO:0006915).[15][17] Its molecular functions include protein serine/threonine kinase activity (GO:0004674) and death receptor binding (GO:0005123). The pathogenic variants in IMD57 therefore result in disruption of these processes and functions, with downstream consequences for immune cell survival, cytokine production, and tissue integrity.[12][15][18]

4.4 Epigenetic and Structural Genomic Considerations

There is currently no evidence that epigenetic changes (e.g., DNA methylation, histone modifications) or large-scale chromosomal abnormalities play a primary role in IMD57 beyond the documented large deletions involving RIPK1, which are structural genetic variants rather than epigenetic phenomena.[3][14] ClinGen notes that two large deletions affecting RIPK1 have been identified in IMD57 patients, underscoring that structural variants can cause the disease if they abolish RIPK1 expression.[3] However, no broader chromosomal syndromes or microdeletion syndromes associated with RIPK1 locus have been described in this context.

The RIPK1 locus lies on chromosome 6p25.2, a region that can be involved in various structural variants in other conditions, but the IMD57 phenotype is specifically attributable to disruption of RIPK1 rather than to contiguous gene deletion syndromes.[14] There are no reports of epigenetic silencing of RIPK1 causing IMD57, and epigenomic studies in IMD57 patients have not been reported.

5. Environmental Information

5.1 Non-Genetic Contributing Factors

As a Mendelian primary immunodeficiency with a clear genetic cause, IMD57 does not have known non-genetic causal factors. However, environmental exposures influence the phenotypic expression and complications of the disease. Patients are highly susceptible to bacterial, viral, and fungal infections, particularly in the gastrointestinal and respiratory tracts, and the frequency and severity of these infections depend on environmental pathogen burden, vaccination coverage, sanitation, and healthcare access.[3][5][18] Even common respiratory viruses or enteric pathogens that cause mild disease in immunocompetent children can lead to severe, recurrent, or chronic infections in IMD57 patients, contributing to lung damage (bronchiectasis) and exacerbation of IBD.[5][18]

Inflammatory triggers such as infections, endotoxin exposure, and perhaps microbiome composition are especially relevant given the central role of RIPK1 in TNFR, TLR, and interferon signaling.[13][15][17] In RIPK1-deficient mice, systemic exposure to TNF or TLR agonists can cause catastrophic necroptosis and fatal systemic inflammation, illustrating how environmental inflammatory signals can unmask the consequences of RIPK1 loss.[13][16] Although human IMD57 patients are not complete Ripk1 knockouts (e.g., some may have residual scaffolding function), these animal data suggest that environmental inflammatory cues have disproportionate effects in the setting of RIPK1 deficiency.[12][18]

5.2 Lifestyle and Infectious Contexts

Lifestyle factors such as diet, hygiene, and exposure to crowded environments may modulate infection risk in IMD57, but there is no evidence that they independently drive disease onset. Nonetheless, standard public health measures—hand hygiene, infection control, safe drinking water, vaccination of contacts—are particularly important for these patients to reduce infection burden.[5][18]

Given the prominent IBD phenotype, diet may influence symptom severity, as in other forms of IBD, but the underlying pathophysiology is driven by RIPK1 deficiency rather than nutritional factors. From a clinical standpoint, carefully managed nutrition, including elemental diets, enteral feeding, or parenteral nutrition when necessary, can mitigate malnutrition and failure to thrive, but these interventions are supportive rather than etiologic.[5][18]

There is no evidence that specific toxins, pollutants, radiation, or occupational exposures contribute to IMD57 pathogenesis. Infectious agents are important as triggers and complicating factors, but not as primary causes, and there is no specific pathogen uniquely associated with IMD57 beyond the general susceptibility to opportunistic or severe infections.[3][5][18]

6. Mechanism and Pathophysiology

6.1 High-Level Causal Chain

At a high level, the pathophysiology of Immunodeficiency 57 can be conceptualized as a sequential causal chain linking the initiating genetic lesion to clinical manifestations. Step 1: Biallelic loss-of-function mutations in RIPK1 abolish or severely reduce RIPK1 protein expression or function in hematopoietic and possibly non-hematopoietic cells.[3][14][18] Step 2: This loss of RIPK1 disrupts its scaffolding role in TNFR1, TLR, and RIG-I-like receptor signaling complexes, leading to impaired activation of NF-κB and MAPKs and altered cytokine production in response to inflammatory stimuli; this step is directly demonstrated in human patient cells and inferred from mouse models.[3][12][18] Step 3: In parallel, the absence of RIPK1’s prosurvival scaffold function renders cells—particularly immune cells—hypersensitive to caspase-8–dependent apoptosis and RIPK3-MLKL–dependent necroptosis in response to TNF and other signals, as demonstrated in mouse models and supported by increased necroptosis in RIPK1-deficient human cells.[13][16][18] Step 4: The combination of impaired NF-κB/MAPK signaling and increased programmed cell death leads to lymphopenia, impaired T-cell and innate immune function, and defective host defense, resulting in recurrent severe infections; this step is inferred from immunophenotyping and functional assays in patients.[3][18] Step 5: At the same time, the propensity for necroptosis and dysregulated cytokine production in myeloid and other cells leads to chronic autoinflammation, particularly in the gut, joints, and skin, manifesting as early-onset IBD, polyarthritis, and vasculitis; this step is supported by clinical observation and by animal models showing that excessive necroptosis drives systemic inflammation.[12][13][16][18] Step 6: Repeated cycles of infection, tissue damage, and autoinflammation cause cumulative organ damage, including bronchiectasis, growth failure, and joint destruction, culminating in the full clinical spectrum of IMD57.[3][5][18]

6.2 RIPK1 Structure, Pathways, and Biological Roles

RIPK1 is a modular protein comprising an N-terminal serine/threonine kinase domain, an intermediate region containing a RIP homotypic interaction motif (RHIM), and a C-terminal death domain.[14][15][17] This architecture allows RIPK1 to participate in multiple protein–protein interactions and signaling complexes. In TNFR1 signaling, RIPK1 is recruited to the receptor complex (complex I) via its death domain and interacts with TRADD, TRAF2, and LUBAC, thereby promoting the formation of a polyubiquitinated signaling platform that activates NF-κB and MAPKs.[13][15][17] In TLR3 and TLR4 signaling, RIPK1 interacts with the adaptor TRIF via RHIM, linking pattern-recognition receptor signaling to downstream NF-κB and MAPKs.[13][15] RIPK1 also participates in signaling downstream of interferon receptors, RIG-I-like receptors, and STING, integrating antiviral and inflammatory responses.[15][17]

Depending on context, RIPK1’s kinase activity and scaffolding function can have opposing effects. In its scaffolding role, RIPK1 supports cell survival and proinflammatory gene expression, primarily via NF-κB activation; these functions are largely kinase independent.[13][15][17] In contrast, when deubiquitinated and released from receptor complexes, RIPK1’s kinase activity promotes formation of cytosolic complexes (complex II, ripoptosome) that recruit FADD and caspase-8, leading to apoptosis, or interact with RIPK3 and MLKL, leading to necroptosis.[13][16][17]

Kaiser et al. demonstrated that RIPK1 suppresses innate immune necrotic and apoptotic cell death during mammalian parturition, showing that a kinase-independent prosurvival role of RIPK1 prevents lethal consequences of RIP3-dependent necroptosis and caspase-8–dependent apoptosis.[13] In their PNAS 2014 article, they observed that Rip1-deficient mice die perinatally with gross immune system abnormalities, and that triple deficiency of RIP1, RIP3, and caspase-8 rescues viability and immune competence, underscoring RIPK1’s central role in balancing cell death pathways.[13][16]

Recent reviews further highlight RIPK1 as a critical molecular switch in cell fate decisions. A 2025 Frontiers review notes that “RIPK1 acts as a critical molecular switch, balancing cell survival and death in response to environmental cues,” and that its scaffolding function can be protective, whereas its kinase activity can drive cell death and inflammation when aberrantly activated.[17] An earlier ScienceDirect overview calls RIPK1 a “Swiss Army knife” of innate immune regulation, linked to TNFRs, TLRs, IFNAR1, STING, and MAVS, and controlling necroptosis, apoptosis, pyroptosis, and inflammatory gene expression.[15]

6.3 Consequences of RIPK1 Loss-of-Function in Humans

The human IMD57 phenotype provides direct evidence of what happens when RIPK1 is absent in the immune system. Cuchet-Lourenço et al. summarized their key findings as follows:

“RIPK1 (receptor-interacting serine/threonine kinase 1) is a master regulator of signaling pathways leading to inflammation and cell death and is of medical interest as a drug target. We report four patients from three unrelated families with complete RIPK1 deficiency caused by rare homozygous mutations. The patients suffered from recurrent infections, early-onset inflammatory bowel disease, and progressive polyarthritis. They had immunodeficiency with lymphopenia and altered production of various cytokines revealed by whole-blood assays. In vitro, RIPK1-deficient cells showed impaired mitogen-activated protein kinase activation and cytokine secretion and were prone to necroptosis. Hematopoietic stem cell transplantation reversed cytokine production defects and resolved clinical symptoms in one patient. Thus, RIPK1 plays a critical role in the human immune system.”[18]

This abstract encapsulates the mechanistic consequences of RIPK1 LoF: impaired MAPK and cytokine responses, increased necroptosis, lymphopenia, and clinical immunodeficiency/autoinflammation. ClinGen’s curation corroborates these findings, emphasizing that loss of RIPK1 disrupts MAPK p38 phosphorylation and subsequent IL-6, IL-10, TNF-α, and IL-12 production, while promoting excessive IL-1β production.[3] The increased necroptosis presumably reflects loss of RIPK1’s prosurvival scaffolding function, which normally restrains RIPK3/MLKL activation.[13][16][18]

From a GO perspective, loss of RIPK1 disrupts processes such as positive regulation of NF-kappaB transcription factor activity (GO:0051092), regulation of necroptotic process (GO:0060545), and innate immune response (GO:0045087). Immune cell types affected include T lymphocytes (CL:0000084), B lymphocytes (CL:0000236), NK cells (CL:0000623), and myeloid cells such as monocytes/macrophages (CL:0000235).[3][12][18]

6.4 Immunodeficiency: T-cell Lymphopenia and Defective Cytokine Responses

The immunodeficiency in IMD57 arises from a combination of lymphopenia and defective cytokine responses. ClinGen notes that “T-cell lymphopenia is typically observed, while B-cell and NK cell counts may be normal or decreased,” and that all patients have recurrent bacterial, viral, and fungal infections.[3] The T-cell defect likely results from increased apoptosis or necroptosis of developing or peripheral T cells due to loss of RIPK1’s prosurvival scaffold function in response to TNF and other signals, as suggested by mouse models where RIPK1 deficiency leads to profound lymphoid abnormalities.[13][16][17]

RIPK1-deficient human cells also show impaired activation of MAPK pathways (e.g., p38, ERK) and reduced production of proinflammatory cytokines in response to TLR and TNF stimulation, weakening innate immune responses to pathogens.[3][18] At the same time, increased IL-1β production reflects dysregulated inflammasome activation or necroptosis-driven DAMP release, contributing to autoinflammation rather than effective antimicrobial defense.[3][12][18]

These defects collectively impair both innate immunity (monocyte, macrophage, dendritic cell responses to TLR ligands, IFN, and TNF) and adaptive immunity (T-cell survival and activation), leading to susceptibility to opportunistic infections across multiple pathogen classes.[3][5][18] GO terms relevant here include T cell mediated immunity (GO:0002456), adaptive immune response (GO:0002250), and cytokine production involved in immune response (GO:0002367).

6.5 Autoinflammation and Tissue Damage: Necroptosis and Dysregulated Cytokines

Paradoxically, the same loss-of-function in RIPK1 also promotes autoinflammation, particularly in the gut, joints, and skin. This arises from the dual role of RIPK1 in suppressing inappropriate necroptosis and apoptosis. Kaiser et al. showed that Rip1-deficient mice develop perinatal lethality with massive necroptosis and apoptosis in response to innate immune stimuli, and that this lethal phenotype can be rescued by deleting RIP3 and caspase-8, indicating that RIPK1 normally restrains both pathways.[13][16]

In IMD57 patients, RIPK1-deficient cells are “prone to necroptosis,” as demonstrated experimentally.[18] Necroptosis is a proinflammatory form of cell death in which RIPK3 phosphorylates MLKL, leading to membrane permeabilization and release of DAMPs and cytokines such as IL-1α, IL-1β, and HMGB1.[16][17] A 2025 Frontiers review notes that “activation of RIPK1-dependent necroptosis is caspase-independent and involves RIPK1/RIPK3-dependent activation of MLKL, resulting in membrane permeabilization and subsequent release of proinflammatory cytokines and chemokines upon necroptosis-mediated cell death,” although in RIPK1 deficiency, RIPK3-MLKL activation may occur via alternative pathways.[17]

Dysregulated IL-1β production is a key feature: ClinGen notes that loss of RIPK1 leads to excessive IL-1β production, which can drive autoinflammatory manifestations such as arthritis, IBD, and vasculitis.[3] In the gut, increased necroptosis or apoptosis of epithelial and immune cells may disrupt barrier integrity, allowing microbial translocation and chronic inflammation, while dysregulated cytokines perpetuate mucosal immune activation, producing early-onset IBD.[10][12][18] In joints, similar mechanisms—cell death, DAMP release, and IL-1/TNF/IL-6–driven synovial inflammation—likely underlie inflammatory polyarthritis.

Thus, IMD57 can be viewed as a “loss-of-function immunodeficiency with gain-of-function autoinflammation”, in which the absence of a regulatory hub leads to both impaired host defense and exaggerated inflammatory cell death. This duality is a hallmark of many primary immune regulatory disorders and illustrates the delicate balance maintained by RIPK1 in healthy individuals.[3][12][17]

6.6 Branching Mechanistic Pathways and Upstream/Downstream Relationships

From an ordered causal perspective, several branching mechanisms can be delineated. Upstream, the initiating event is germline RIPK1 LoF, present in all cells but especially consequential in hematopoietic lineages. In response to environmental triggers (TNF, TLR ligands, interferons, viral RNA, bacterial products), multiple pathways diverge.

One branch involves TNFR1 signaling. In normal cells, TNFR1 engagement recruits TRADD, RIPK1, TRAF2/5, and LUBAC to form complex I, leading to NF-κB activation and expression of survival and inflammatory genes.[13][15][17] In RIPK1-deficient cells, TRADD and other adaptors may still signal, but the absence of RIPK1 undermines complex stability and NF-κB activation, while also predisposing to formation of death-inducing complexes (complex II) that engage caspase-8 even more readily.[13][17][18]

Another branch involves TLR3/4–TRIF–RIPK1 signaling. Normally, TLR3/4 activation via TRIF recruits RIPK1 through RHIM, linking TLR activation to NF-κB and MAPK pathways.[13][15] In the absence of RIPK1, TRIF-dependent signaling may be skewed toward cell death pathways or rendered ineffective for cytokine induction, compromising antiviral and antibacterial responses.[13][15][18]

A third branch concerns interferon and RIG-I-like receptor pathways. RIPK1 participates in some of these pathways, and its absence may reduce type I IFN responses or alter the balance between antiviral defense and inflammatory cell death, although detailed human data in IMD57 are limited.[15][17]

Downstream of these branches, two major outcome pathways emerge: immune cell depletion and functional impairment, leading to immunodeficiency, and excessive inflammatory cell death and cytokine release, leading to autoinflammation and tissue damage. These processes engage multiple cell types, including T cells (CL:0000084), B cells (CL:0000236), NK cells (CL:0000623), macrophages (CL:0000235), dendritic cells (CL:0000451), and intestinal epithelial cells (CL:0000069).[3][12][18]

7. Anatomical Structures Affected

7.1 Organ-Level Involvement

IMD57 primarily affects the immune system and gastrointestinal tract, with secondary involvement of musculoskeletal, pulmonary, hepatic, and cutaneous systems. The immune system involvement encompasses lymphoid organs such as thymus, lymph nodes, spleen (UBERON:0002106), and bone marrow (UBERON:0002371), reflected clinically in lymphopenia, hypogammaglobulinemia, and recurrent infections.[3][5][11][18] Hepatosplenomegaly (UBERON:0002107 and UBERON:0002108) suggests enlargement of liver and spleen due to chronic immune activation.[5][18]

The gastrointestinal tract involvement includes small intestine (UBERON:0002108), colon (UBERON:0001155), and upper GI tract structures such as stomach (UBERON:0000945), as patients present with enterocolitis, gastritis, diarrhea, and perianal disease.[5][10][18] Genomics England categorizes RIPK1 under “infantile enterocolitis & monogenic inflammatory bowel disease,” underscoring the gut as a major target organ.[10]

Musculoskeletal involvement manifests as polyarthritis affecting multiple joints, potentially including knees, ankles, wrists, and small joints of hands and feet (various UBERON joint terms), reflecting synovial inflammation and joint damage.[3][5][18] Pulmonary involvement includes chronic lung disease and bronchiectasis (UBERON:0002048 for lung), likely secondary to recurrent infections and immune dysregulation.[5][18] Skin and vascular involvement appears as rash and lymphocytic vasculitis, affecting dermis and small blood vessels.[5][12]

7.2 Tissue- and Cell-Level Targets

At the tissue level, IMD57 affects lymphoid tissue, intestinal mucosa, synovial tissue, lung parenchyma, and skin. In lymphoid tissue, T-cell zones are likely depleted or dysfunctional due to lymphopenia and increased apoptosis, while germinal center reactions may be impaired, contributing to defective antibody responses.[3][18] In intestinal mucosa, chronic inflammatory infiltrates, epithelial cell death, and disrupted barrier integrity characterize early-onset IBD.[10][12][18] Synovial tissue exhibits inflammatory infiltrates and pannus formation consistent with autoinflammatory arthritis.

Key cell types include T lymphocytes (CL:0000084), B lymphocytes (CL:0000236), NK cells (CL:0000623), monocytes/macrophages (CL:0000235), dendritic cells (CL:0000451), neutrophils (CL:0000096), and intestinal epithelial cells (CL:0000069).[3][12][18] RIPK1’s role in these cells encompasses regulation of survival, cytokine production, and response to TNF and TLR ligands; its absence leads to context-dependent cell death and dysfunction.[12][15][17][18]

7.3 Subcellular Compartments and Localization

Though RIPK1 is a cytosolic kinase, its functions are associated with specific subcellular compartments. It is recruited to the plasma membrane–proximal TNFR1 complex I (GO Cellular Component: TNF-alpha/NF-kappa B signaling complex GO:0031264), and it participates in cytosolic complexes such as the ripoptosome and necrosome.[13][15][17] RIPK1 also localizes to cytosolic signaling complexes downstream of TLRs and RIG-I-like receptors, and its kinase activity influences events at the plasma membrane, cytoplasm, and possibly mitochondria through downstream necroptotic effectors like MLKL.[16][17]

In IMD57, loss of RIPK1 means these complexes either do not form properly (e.g., complex I) or form aberrantly (e.g., death-inducing complexes without appropriate regulation), altering signaling in cellular compartments such as plasma membrane, cytosol (GO:0005829), and nucleus (GO:0005634) where NF-κB and other transcription factors act.[13][15][17][18]

8. Temporal Development

8.1 Age of Onset and Early Disease Course

IMD57 is a pediatric-onset disease, with symptoms beginning in neonatal period or infancy, typically within the first year of life.[3][5][11][18] OMIM notes that recurrent infections start in the first year of life, and MalaCards lists onset in “infancy, neonatal.”[5][11] ClinGen emphasizes that early-onset IBD and infections are invariant features during early childhood.[3] Thus, age-of-onset HPO terms such as Neonatal onset (HP:0003623) and Infantile onset (HP:0003593) apply.

The onset pattern is chronic and insidious rather than acute. Infants may present initially with persistent diarrhea, failure to thrive, and recurrent respiratory or systemic infections, and over months to years they develop progressive arthritis and additional complications.[5][18] Some may be misdiagnosed initially with nonspecific severe combined immunodeficiency, early-onset IBD, or juvenile idiopathic arthritis before the full constellation of features and genetic diagnosis clarifies the underlying syndrome.[3][12][18]

8.2 Disease Progression, Course, and Duration

The disease course of IMD57 appears chronic and progressive, with ongoing enterocolitis, arthritis, and recurrent infections, punctuated by acute exacerbations triggered by infections or other inflammatory stimuli.[3][5][18] Over time, recurrent infections can lead to chronic lung disease and bronchiectasis; chronic intestinal inflammation can cause strictures, malabsorption, and growth failure; and chronic arthritis can result in joint damage and disability.[5][18]

Without curative interventions such as HSCT, the disease is likely lifelong and life-limiting. However, the limited number of reported cases and the recency of diagnosis make it difficult to define precise natural history, survival curves, or progression stages. One can conceptually define an early stage dominated by infections and gastrointestinal symptoms, an intermediate stage with established chronic organ damage (lung, joints), and an advanced stage with severe systemic complications and potential organ failure, but these stages have not been formalized in the literature.[3][5][12][18]

Response to HSCT in at least one patient suggests that the disease course can be reset by reconstituting RIPK1-sufficient hematopoietic cells, leading to resolution of infections and IBD.[18] However, if significant organ damage has already occurred (e.g., bronchiectasis, joint destruction), some sequelae may be irreversible, emphasizing the importance of early diagnosis and intervention.

8.3 Remission Patterns and Critical Periods

Spontaneous remissions are not described in IMD57; rather, disease activity fluctuates with triggers such as infections but remains chronic without definitive treatment. Immunosuppressive or biologic therapies (e.g., anti-TNF) may induce partial remission of IBD or arthritis in some monogenic IBD cases, but specific data for IMD57 are sparse in the summarized sources.[10][12][18] These therapies,

Reference Validation

Checked with linkml-reference-validator 0.2.1.

Outcome Count
References checked 7
Resolved 7
Unresolved (possible confabulation) 0
Unverifiable 0
References weighed for topical relevance 7
On topic 5
Off topic 0

All extracted references resolved successfully.

Term Validation

Checked with linkml-term-validator 0.4.5, through the ols: adapter.

Outcome Count
Terms checked 64
Resolved 58
Unresolved (possible confabulation) 1
Obsolete 2
Unverifiable 3
Terms whose name was checked 37
Terms named correctly 20
Terms named as a different term 9
Terms whose name is worth a second look 8

Terms the report names something else

These identifiers resolve, so nothing about them looks wrong, and the ontology calls them something unrelated to what the report calls them. That usually means the identifier is not the one the sentence needs:

  • HP:0012404 (3 mentions) - the report calls it "Early-onset inflammatory bowel disease"; HP calls it Abnormal urine citrate concentration
  • HP:0003481 (2 mentions) - the report calls it "Inflammatory arthritis"; HP calls it Segmental peripheral demyelination/remyelination
  • HP:0001883 (2 mentions) - the report calls it "Decreased T cell count"; HP calls it Talipes
  • HP:0002110 (2 mentions) - the report calls it "Recurrent lower respiratory tract infections", "Bronchiectasis"; HP calls it Bronchiectasis
  • HP:0002597 (1 mention) - the report calls it "Inflammatory bowel disease"; HP calls it Abnormality of the vasculature
  • HP:0002038 (1 mention) - the report calls it "Chronic diarrhea"; HP calls it Protein avoidance
  • HP:0002240 (1 mention) - the report calls it "Gastrointestinal hemorrhage"; HP calls it Hepatomegaly
  • HP:0002635 (2 mentions) - the report calls it "Cutaneous vasculitis", "Leukocytoclastic vasculitis"; HP calls it Type IV atherosclerotic lesion
  • HP:0012091 (1 mention) - the report calls it "Decreased NK cell count"; HP calls it Abnormality of pancreas physiology

Unresolved terms

These identifiers do not exist in an ontology that resolved other terms from the same prefix, so they were most likely invented:

  • HP:0003479 (1 mention), reported as "Polyarthritis" - HP does not contain this term

Obsolete terms

These terms are real but deprecated. Citing one is not a fabrication; it does mean the report is naming something the ontology has retired:

  • GO:0032088 (obsolete negative regulation of NF-kappaB transcription factor activity) (1 mention)
  • GO:0051092 (obsolete positive regulation of NF-kappaB transcription factor activity) (1 mention)

Terms whose name is worth a second look

The report's name for these is recognisably related to the term's own name without being one of them. A loose paraphrase reads the same way as a citation of the wrong sibling term - and so does a related synonym, which the ontology records precisely because it names something adjacent rather than the same thing - so these are listed rather than judged:

  • HP:0004313 (2 mentions) - the report calls it "hypogammaglobulinemia"; HP calls it Decreased circulating immunoglobulin concentration, and lists "Hypogammaglobulinemia" among its other names
  • HP:0001371 (1 mention) - the report calls it "Joint contracture"; HP calls it Flexion contracture
  • HP:0004322 (1 mention) - the report calls it "Decreased B cell count"; HP calls it Short stature, and lists "Decreased body height" among its other names
  • HP:0004315 (1 mention) - the report calls it "Abnormal immunoglobulin level"; HP calls it Decreased circulating IgG concentration, and lists "Decreased immunoglobulin G" among its other names
  • GO:0033209 (1 mention) - the report calls it "TNF-mediated signaling pathway"; GO calls it tumor necrosis factor-mediated signaling pathway, and lists "TNF-alpha-mediated signaling pathway" among its other names
  • GO:0032088 (1 mention) - the report calls it "regulation of NF-kappaB transcription factor activity"; GO calls it obsolete negative regulation of NF-kappaB transcription factor activity
  • GO:0051092 (1 mention) - the report calls it "positive regulation of NF-kappaB transcription factor activity"; GO calls it obsolete positive regulation of NF-kappaB transcription factor activity
  • GO:0060545 (1 mention) - the report calls it "regulation of necroptotic process"; GO calls it positive regulation of necroptotic process

Terms named inconsistently

The report gives these identifiers more than one name of its own:

  • HP:0002110 - called "Recurrent lower respiratory tract infections", "Bronchiectasis"
  • HP:0002635 - called "Cutaneous vasculitis", "Leukocytoclastic vasculitis"

Prefixes with no resolver

Terms carrying these prefixes were not checked either way, because no configured ontology covers them. An unrecognised prefix may name an ontology this run could not reach as easily as one that does not exist, so nothing here is evidence of fabrication: DO, OMIM.