TNF Receptor-Associated Periodic Syndrome

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Classifications

Harrison's Chapter

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Inheritance

1

Autosomal dominant inheritance HP:0000006

TRAPS is caused by heterozygous pathogenic variants in TNFRSF1A and is transmitted in an autosomal dominant manner, with each child of an affected individual having a 50% risk of inheriting the variant. Penetrance is high for cysteine-disrupting variants and T50M but markedly reduced for the common R92Q and P46L variants.

Autosomal dominant inheritance Penetrance: INCOMPLETE Expressivity: VARIABLE

Show evidence (2 references)

PMID:10199409 SUPPORT Human Clinical

"Autosomal dominant periodic fever syndromes are characterized by unexplained episodes of fever and severe localized inflammation."

McDermott et al. established TRAPS as an autosomal dominant periodic fever syndrome.

PMID:23965844 SUPPORT Human Clinical

"A family history was present in 19% of patients with R92Q and 64% of those with other variants."

The Eurofever/EUROTRAPS registry documents dominant transmission with variant-dependent family history, reflecting incomplete penetrance for R92Q.

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Discussions and Knowledge Gaps

1

Do the TNFR1 knock-in mouse models of TRAPS reproduce the full human periodic-fever and AA-amyloidosis phenotype, or only the cellular/molecular phenotype?

HUMAN MODEL MISMATCH OPEN traps_mouse_model_mismatch

Attached to

pathophysiology#TNFRSF1A Misfolding and ER Retention

Mouse knock-in models and patient-derived cells faithfully reproduce the molecular phenotype of TRAPS (ER retention of mutant TNFR1, elevated mitochondrial ROS, and hyper-responsive innate cytokine secretion). However, the dramatic recurrent multi-organ human attacks and progression to AA amyloidosis are incompletely captured in animal models, so translational validity for the clinical syndrome (as opposed to the cell-biological mechanism) remains an open question.

Proposed experiments

Longitudinal natural-history phenotyping of TNFR1 knock-in mice

exp_traps_knockin_natural_history

Perform longitudinal phenotyping of TNFR1 knock-in mice for spontaneous febrile and serositis attacks and for renal AA amyloid deposition under inflammatory challenge, to test whether the clinical periodic-fever and amyloidosis phenotype, not just the cellular phenotype, is recapitulated.

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Pathophysiology

4

TNFRSF1A Misfolding and ER Retention

Pathogenic TNFRSF1A variants, especially cysteine-residue substitutions that disrupt conserved extracellular disulfide bonds, cause misfolding of the TNFR1 protein. The mutant receptor forms abnormal disulfide-linked oligomers, fails to bind TNF, and is retained intracellularly in the endoplasmic reticulum rather than trafficking to the cell surface, distinguishing the mechanism from a simple loss of the soluble TNF-decoy receptor.

monocyte CL:0000576

TNFRSF1A

response to endoplasmic reticulum stress GO:0034976 ↑ INCREASED ERAD pathway GO:0036503

Downstream

Enhanced Innate Cytokine Signaling ER retention of misfolded TNFR1 drives ER stress and elevated mitochondrial reactive oxygen species, lowering the threshold for innate immune activation and amplifying pro-inflammatory cytokine production.

Show evidence (2 references)

PMID:16684962 SUPPORT In Vitro

"Instead, TRAPS mutant TNFR1 formed abnormal disulfide-linked oligomers that failed to interact with wild-type TNFR1 molecules through the preligand assembly domain (PLAD)"

Lobito et al. (transfected cells) demonstrated that TRAPS-mutant TNFR1 forms abnormal disulfide-linked oligomers.

PMID:16684962 SUPPORT Model Organism

"TRAPS mutant TNFR1 molecules were retained intracellularly and colocalized with endoplasmic reticulum (ER) markers."

In a mouse knock-in model and transfected cells, mutant TNFR1 was retained in the ER, supporting the misfolding/ER-retention model.

Enhanced Innate Cytokine Signaling

Misfolded ER-retained TNFR1 raises mitochondrial reactive oxygen species, which potentiate MAPK signaling and the LPS-driven production of a broad set of pro-inflammatory cytokines (IL-1 beta, IL-6, and TNF) by monocytes and macrophages. This enhanced innate immune responsiveness, rather than loss of TNF decoy function, drives the autoinflammatory state.

monocyte CL:0000576 macrophage CL:0000235 neutrophil CL:0000775

reactive oxygen species metabolic process GO:0072593 ↑ INCREASED interleukin-1 beta production GO:0032611 ↑ INCREASED interleukin-6 production GO:0032635 ↑ INCREASED tumor necrosis factor production GO:0032640 ↑ INCREASED inflammatory response GO:0006954 ↑ INCREASED

Downstream

Systemic Autoinflammation Amplified IL-1 beta, IL-6, and TNF secretion drives recurrent systemic inflammatory attacks of fever, serositis, myalgia, and rash.

Show evidence (2 references)

PMID:21282379 SUPPORT In Vitro

"A variety of antioxidants dampen LPS-induced MAPK phosphorylation and inflammatory cytokine production."

Mitochondrial ROS potentiate MAPK signaling and LPS-induced cytokine production in TRAPS cells, the mechanistic basis of enhanced innate signaling.

PMID:21282379 SUPPORT Model Organism

"TNFR1 mutant cells exhibit altered mitochondrial function with enhanced oxidative capacity and mitochondrial ROS generation"

Mouse embryonic fibroblasts harboring TRAPS mutations show enhanced mitochondrial ROS generation driving the inflammatory phenotype.

Systemic Autoinflammation

Recurrent, prolonged sterile inflammatory attacks affecting multiple systems: fever, sterile peritonitis, migratory myalgia with overlying rash, periorbital edema, conjunctivitis, arthralgia, and serositis, accompanied by a marked acute-phase response.

neutrophil CL:0000775 monocyte CL:0000576

inflammatory response GO:0006954 ↑ INCREASED

peritoneum UBERON:0002358 skeletal muscle tissue UBERON:0001134

Downstream

AA Amyloidosis Chronic and subclinical inflammation between attacks sustains elevation of serum amyloid A, leading to deposition of AA amyloid fibrils, predominantly in the kidney, causing proteinuria and progressive renal failure.

Show evidence (1 reference)

PMID:11443543 SUPPORT Human Clinical

"which is characterized by attacks of fever, sterile peritonitis, arthralgia, myalgia, skin rash, and/or conjunctivitis; some patients also develop systemic amyloidosis."

TRAPS attacks involve fever, sterile peritonitis, arthralgia, myalgia, skin rash, and conjunctivitis.

AA Amyloidosis

Reactive (AA) systemic amyloidosis arising from chronically elevated serum amyloid A, with renal-predominant amyloid fibril deposition leading to proteinuria, nephrotic syndrome, and progressive kidney failure. It is the principal organ-threatening, potentially fatal complication of TRAPS and is largely preventable with sustained suppression of inflammation.

kidney UBERON:0002113

Show evidence (1 reference)

PMID:23965844 SUPPORT Human Clinical

"AA amyloidosis has developed in 16 (10%) patients at a median age of 43 years."

AA amyloidosis developed in 10% of the Eurofever/EUROTRAPS registry patients at a median age of 43 years.

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Pathograph

Use the checkboxes to hide or show graph categories. Hover nodes for evidence and cross-linked metadata.

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Phenotypes

10

Cardiovascular 2

Conjunctivitis FREQUENT Conjunctivitis HP:0000509

Ocular inflammation; part of the characteristic eye manifestations of TRAPS.

Show evidence (2 references)

PMID:23965844 SUPPORT Human Clinical

"fever (88%), limb pain (85%), abdominal pain (74%), rash (63%) and eye manifestations (45%)"

Eye manifestations, including conjunctivitis, were present in 45% of registry patients (FREQUENT).

PMID:11443543 SUPPORT Human Clinical

"attacks of fever, sterile peritonitis, arthralgia, myalgia, skin rash, and/or conjunctivitis"

Conjunctivitis is among the defining manifestations of TRAPS attacks.

Lymphadenopathy Lymphadenopathy HP:0002716

More common in children at presentation.

Show evidence (1 reference)

PMID:23965844 SUPPORT Human Clinical

"Children were more likely than adults to present with lymphadenopathy, periorbital oedema and abdominal pains."

Lymphadenopathy is a recognized TRAPS manifestation, more frequent in children.

Genitourinary 1

Proteinuria Proteinuria HP:0000093

Manifestation of renal AA amyloidosis; the basis for renal surveillance in TRAPS.

Show evidence (1 reference)

PMID:36375008 SUPPORT Other

"Proteinuria and kidney failure occur in 80%-90% of affected individuals with amyloidosis"

Proteinuria and kidney failure occur in 80-90% of TRAPS patients who develop amyloidosis.

Metabolism 2

Recurrent Prolonged Fever VERY_FREQUENT Recurrent fever HP:0001954

Temporal: PROLONGED

Hallmark of TRAPS; attacks characteristically last 5-25 days (often more than one week), longer than the short attacks of FMF and MKD.

Show evidence (2 references)

PMID:23965844 SUPPORT Human Clinical

"Attacks were recurrent in 88% and the commonest features associated with the pathogenic variants were fever (88%)"

Fever was present in 88% of registry patients (VERY_FREQUENT), with recurrent attacks in 88%.

PMID:36375008 SUPPORT Other

"episodes of inflammation typically occurring every four to six weeks and lasting between five and 25 days."

GeneReviews documents the characteristically prolonged 5-25 day attacks.

AA Amyloidosis OCCASIONAL Amyloid deposition HP:0011034

Late complication; renal-predominant AA amyloidosis, the major cause of TRAPS mortality.

Show evidence (1 reference)

PMID:23965844 SUPPORT Human Clinical

"AA amyloidosis has developed in 16 (10%) patients at a median age of 43 years."

AA amyloidosis developed in 10% of registry patients (OCCASIONAL).

Constitutional 3

Myalgia VERY_FREQUENT Myalgia HP:0003326

Characteristically migratory, due to underlying monocytic fasciitis, often with overlying erythematous rash.

Show evidence (1 reference)

PMID:23965844 SUPPORT Human Clinical

"fever (88%), limb pain (85%), abdominal pain (74%), rash (63%) and eye manifestations (45%)"

Limb pain (encompassing myalgia) was present in 85% of registry patients (VERY_FREQUENT).

Abdominal Pain FREQUENT Abdominal pain HP:0002027

Sterile peritonitis; may mimic a surgical abdomen.

Show evidence (1 reference)

PMID:23965844 SUPPORT Human Clinical

"fever (88%), limb pain (85%), abdominal pain (74%), rash (63%) and eye manifestations (45%)"

Abdominal pain was present in 74% of registry patients (FREQUENT).

Arthralgia FREQUENT Arthralgia HP:0002829

Show evidence (1 reference)

PMID:11443543 SUPPORT Human Clinical

"attacks of fever, sterile peritonitis, arthralgia, myalgia, skin rash, and/or conjunctivitis"

Arthralgia is a defining manifestation of TRAPS attacks.

Other 2

Migratory Erythematous Rash FREQUENT Migratory erythematous plaque HP:0033622

Migratory erythematous rash that characteristically overlies the painful muscle group.

Show evidence (1 reference)

PMID:23965844 SUPPORT Human Clinical

"fever (88%), limb pain (85%), abdominal pain (74%), rash (63%) and eye manifestations (45%)"

Rash was present in 63% of registry patients (FREQUENT); in TRAPS it is characteristically migratory and overlies the painful muscle.

Periorbital Edema FREQUENT Periorbital edema HP:0100539

Highly characteristic ocular sign of TRAPS.

Show evidence (1 reference)

PMID:23965844 SUPPORT Human Clinical

"Children were more likely than adults to present with lymphadenopathy, periorbital oedema and abdominal pains."

Periorbital edema is a characteristic eye manifestation of TRAPS, particularly in children.

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Genetic Associations

1

TNFRSF1A (Primary causal gene)

Gene: TNFRSF1A hgnc:11916

Show evidence (3 references)

PMID:10199409 SUPPORT Human Clinical

"In seven affected families, we found six different missense mutations of the 55 kDa tumor necrosis factor receptor (TNFR1), five of which disrupt conserved extracellular disulfide bonds."

The founding genetic study identified TNFRSF1A missense mutations disrupting extracellular disulfide bonds as the cause of TRAPS.

PMID:11443543 SUPPORT Human Clinical

"The increased frequency of P46L and R92Q among patients with periodic fever, as well as functional studies of TNFRSF1A, argue that these are low-penetrance mutations rather than benign polymorphisms."

Aksentijevich et al. established R92Q and P46L as low-penetrance TNFRSF1A variants.

PMID:11443543 SUPPORT Human Clinical

"Genotype-phenotype studies identified, as carriers of cysteine mutations, 13 of 14 patients with TRAPS and amyloidosis and indicated a lower penetrance of TRAPS symptoms in individuals with noncysteine mutations."

Cysteine-disrupting variants are strongly associated with amyloidosis and higher penetrance.

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Medical Actions

5

Anakinra

Action: Pharmacotherapy NCIT:C15986

Recombinant IL-1 receptor antagonist; a first-line IL-1 inhibitor for TRAPS that rapidly controls attacks and acute-phase inflammation and helps prevent AA amyloidosis.

Mechanism Target:

INHIBITS Enhanced Innate Cytokine Signaling — Anakinra blocks IL-1 receptor signaling, neutralizing the amplified IL-1 output of the enhanced innate cytokine signaling node.

Show evidence (1 reference)

PMID:36375008 SUPPORT Other

"Interleukin-1 (IL-1) inhibitors (anakinra or canakinumab) are considered first-line therapies."

GeneReviews designates IL-1 inhibitors anakinra and canakinumab as first-line therapy for TRAPS.

Canakinumab

Action: anti-IL-1 beta monoclonal antibody Ontology label: Pharmacotherapy NCIT:C15986

Agent: monoclonal antibody NCIT:C20401

Anti-IL-1 beta monoclonal antibody; the only biologic with a pivotal randomized controlled trial and regulatory approval for TRAPS, controlling and preventing flares and helping to prevent AA amyloidosis.

Mechanism Target:

INHIBITS Enhanced Innate Cytokine Signaling — Canakinumab neutralizes IL-1 beta, the dominant downstream effector amplified in the enhanced innate cytokine signaling node.

Show evidence (1 reference)

PMID:29768139 SUPPORT Human Clinical

"canakinumab was effective in controlling and preventing flares in patients with colchicine-resistant familial Mediterranean fever, mevalonate kinase deficiency, and TRAPS."

The phase 3 CLUSTER randomized controlled trial showed canakinumab effective in controlling and preventing TRAPS flares.

Etanercept

Action: Pharmacotherapy NCIT:C15986

Agent: etanercept CHEBI:4875

Soluble TNFR2-Fc fusion protein historically used in TRAPS; it reduces symptoms and acute-phase reactants in a dose-dependent manner but does not completely normalize them, and long-term adherence is poor. Note that, unlike etanercept, monoclonal anti-TNF antibodies (infliximab, adalimumab) can paradoxically worsen TRAPS and are generally avoided.

Show evidence (1 reference)

PMID:22006113 SUPPORT Human Clinical

"Etanercept reduces symptoms and serum levels of inflammatory markers of TRAPS in a dose-dependent manner, but does not completely normalize symptoms or acute-phase reactant levels."

Etanercept reduces TRAPS symptoms and inflammatory markers dose-dependently but incompletely.

Corticosteroids

Action: Pharmacotherapy NCIT:C15986

Agent: prednisone CHEBI:8382

High-dose corticosteroids can attenuate acute attacks but are not sufficient for long-term management or for preventing amyloidosis, and chronic use causes toxicity.

Show evidence (1 reference)

PMID:36375008 SUPPORT Other

"The use of corticosteroids may be useful as needed during an acute attack but is not sufficient for long-term management or for preventing amyloidosis."

GeneReviews notes corticosteroids help acute attacks but are insufficient for long-term control or amyloidosis prevention.

Genetic Counseling

Action: Genetic Counseling NCIT:C15240

Counseling regarding autosomal dominant transmission with a 50% risk to offspring, variable expressivity, and the interpretive challenges of the low-penetrance R92Q and P46L variants.

Show evidence (1 reference)

PMID:23965844 SUPPORT Human Clinical

"A family history was present in 19% of patients with R92Q and 64% of those with other variants."

Variant-dependent penetrance and family history support the need for genetic counseling in TRAPS families.

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Biochemical Markers

4

C-Reactive Protein (Elevated)

Show evidence (1 reference)

PMID:36375008 SUPPORT Other

"acute-phase reactants such as C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), and serum amyloid A are typically elevated."

CRP, ESR, and serum amyloid A are elevated during TRAPS flares.

Erythrocyte Sedimentation Rate (Elevated)

Show evidence (1 reference)

PMID:36375008 SUPPORT Other

"acute-phase reactants such as C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), and serum amyloid A are typically elevated."

ESR is elevated as part of the TRAPS acute-phase response.

Serum Amyloid A (Elevated)

Show evidence (1 reference)

PMID:36375008 SUPPORT Other

"acute-phase reactants stabilize between flares but may remain somewhat elevated even in the absence of clinical symptoms."

Persistent elevation of acute-phase reactants including serum amyloid A between flares drives amyloidosis risk.

Soluble TNF Receptor 1 (Reduced)

Show evidence (1 reference)

PMID:10199409 SUPPORT Human Clinical

"Soluble plasma TNFR1 levels in patients were approximately half normal."

McDermott et al. found soluble plasma TNFR1 levels approximately half normal in TRAPS patients.

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Differential Diagnoses

3

Conditions with similar clinical presentations that must be differentiated from TNF Receptor-Associated Periodic Syndrome:

Familial Mediterranean Fever

Distinguishing Features

FMF is autosomal recessive (MEFV), whereas TRAPS is autosomal dominant
FMF attacks are short (1-3 days) and colchicine-responsive, in contrast to the prolonged (5-25 day), colchicine-unresponsive attacks of TRAPS

Mevalonate Kinase Deficiency

Distinguishing Features

MKD (hyper-IgD syndrome, MVK) is autosomal recessive with infantile onset, cervical adenitis, and elevated IgD
MKD attacks are shorter than the prolonged 5-25 day attacks of TRAPS

Cryopyrin-Associated Periodic Syndromes

Distinguishing Features

CAPS (NLRP3) features urticarial rash and, in severe forms, sensorineural hearing loss and CNS involvement
CAPS lacks the migratory myalgia rash, periorbital edema, and prolonged attacks characteristic of TRAPS

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Clinical Trials

1

NCT02059291 PHASE_III COMPLETED

CLUSTER trial: randomized, double-blind, placebo-controlled study of canakinumab in patients with hereditary periodic fevers (TRAPS, HIDS/MKD, or colchicine-resistant FMF), with randomized withdrawal and open-label long-term treatment epochs.

Target Phenotypes: Recurrent fever HP:0001954

Show evidence (1 reference)

clinicaltrials:NCT02059291 SUPPORT

"This study is to determine whether canakinumab is able to induce and maintain a clinically meaningful reduction of disease activity in participants with Hereditary Periodic Fevers (HPF) compared to placebo."

The CLUSTER trial evaluated canakinumab for disease-activity reduction in hereditary periodic fevers including TRAPS.

{ }

Source YAML

click to show

name: TNF Receptor-Associated Periodic Syndrome
creation_date: "2026-06-30T00:00:00Z"
description: >-
  TNF receptor-associated periodic syndrome (TRAPS), formerly familial Hibernian
  fever, is the prototypic autosomal dominant monogenic systemic autoinflammatory
  disorder, caused by heterozygous pathogenic variants in TNFRSF1A (encoding TNF
  receptor 1, TNFR1/p55). It is characterized by recurrent, characteristically
  prolonged fever attacks (typically lasting 5-25 days, often more than one week,
  distinguishing it from the short attacks of familial Mediterranean fever and
  mevalonate kinase deficiency), with migratory erythematous rash overlying
  myalgia, periorbital edema, conjunctivitis, abdominal pain (sterile peritonitis),
  arthralgia, and serositis. The major long-term complication is AA (reactive)
  amyloidosis. Disease-associated cysteine-disrupting and T50M variants cause
  misfolding of TNFR1 and its retention in the endoplasmic reticulum, driving a
  gain of pro-inflammatory function through ER stress, enhanced mitochondrial
  reactive oxygen species, MAPK activation, and amplified innate cytokine
  (IL-1/IL-6/TNF) responses, rather than a simple loss of the soluble TNF-decoy
  receptor. Common low-penetrance variants (R92Q, P46L) cause a milder phenotype.
category: Mendelian
parents:
- Autoinflammatory Disease
- Inherited Disorder
synonyms:
- TRAPS
- TNF receptor-associated periodic fever syndrome
- Familial Hibernian fever
- Autosomal dominant familial periodic fever
disease_term:
  preferred_term: TNF receptor 1-associated periodic fever syndrome
  term:
    id: MONDO:0007727
    label: TNF receptor 1-associated periodic fever syndrome
references:
- reference: PMID:36375008
  title: "TNF Receptor-Associated Periodic Fever Syndrome."
  tags:
  - GeneReviews
inheritance:
- name: Autosomal dominant inheritance
  description: >-
    TRAPS is caused by heterozygous pathogenic variants in TNFRSF1A and is
    transmitted in an autosomal dominant manner, with each child of an affected
    individual having a 50% risk of inheriting the variant. Penetrance is high for
    cysteine-disrupting variants and T50M but markedly reduced for the common
    R92Q and P46L variants.
  inheritance_term:
    preferred_term: Autosomal dominant inheritance
    term:
      id: HP:0000006
      label: Autosomal dominant inheritance
  penetrance: INCOMPLETE
  expressivity: VARIABLE
  evidence:
  - reference: PMID:10199409
    reference_title: "Germline mutations in the extracellular domains of the 55 kDa TNF receptor, TNFR1, define a family of dominantly inherited autoinflammatory syndromes."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Autosomal dominant periodic fever syndromes are characterized by unexplained \nepisodes of fever and severe localized inflammation."
    explanation: McDermott et al. established TRAPS as an autosomal dominant periodic fever syndrome.
  - reference: PMID:23965844
    reference_title: "The phenotype of TNF receptor-associated autoinflammatory syndrome (TRAPS) at presentation: a series of 158 cases from the Eurofever/EUROTRAPS international registry."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "A family history was present in 19% of patients with R92Q and 64% of \nthose with other variants."
    explanation: The Eurofever/EUROTRAPS registry documents dominant transmission with variant-dependent family history, reflecting incomplete penetrance for R92Q.
prevalence:
- population: Worldwide
  evidence:
  - reference: PMID:36375008
    reference_title: "TNF Receptor-Associated Periodic Fever Syndrome."
    supports: PARTIAL
    evidence_source: OTHER
    snippet: "AA amyloidosis, the most severe \nsequela of TRAPS, can largely be avoided with adequate treatment."
    explanation: >-
      GeneReviews describes TRAPS as a rare hereditary periodic fever syndrome; the
      abstract documents the disease and its most severe sequela but does not state
      a precise prevalence figure, so this is partial support for a rare-disease
      characterization only.
progression:
- phase: Onset
  age_range: Early childhood
  evidence:
  - reference: PMID:36375008
    reference_title: "TNF Receptor-Associated Periodic Fever Syndrome."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "Symptoms often begin in early childhood \n(median age 4.3 years), though symptom onset can occur later in life."
    explanation: GeneReviews reports a median onset age of 4.3 years with a wide range.
- phase: Recurrent attacks
  evidence:
  - reference: PMID:36375008
    reference_title: "TNF Receptor-Associated Periodic Fever Syndrome."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "TRAPS) is characterized by \nepisodes of inflammation typically occurring every \nfour to six weeks and lasting between five and 25 days."
    explanation: >-
      GeneReviews documents the characteristically prolonged attacks (5-25 days)
      recurring every four to six weeks, the key feature distinguishing TRAPS from
      the short attacks of FMF and MKD.
genetic:
- name: TNFRSF1A
  association: Primary causal gene
  gene_term:
    preferred_term: TNFRSF1A
    term:
      id: hgnc:11916
      label: TNFRSF1A
  notes: >-
    Encodes TNF receptor 1 (TNFR1/p55, CD120a); autosomal dominant. Pathogenic
    variants cluster in the extracellular cysteine-rich domains. Cysteine-disrupting
    substitutions and T50M are high-penetrance, structural (misfolding) variants
    strongly associated with amyloidosis; R92Q and P46L are common low-penetrance
    variants behaving as susceptibility alleles with a milder phenotype.
  evidence:
  - reference: PMID:10199409
    reference_title: "Germline mutations in the extracellular domains of the 55 kDa TNF receptor, TNFR1, define a family of dominantly inherited autoinflammatory syndromes."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "In seven affected families, \nwe found six different missense mutations of the 55 kDa tumor necrosis factor \nreceptor (TNFR1), five of which disrupt conserved extracellular disulfide bonds."
    explanation: The founding genetic study identified TNFRSF1A missense mutations disrupting extracellular disulfide bonds as the cause of TRAPS.
  - reference: PMID:11443543
    reference_title: "The tumor-necrosis-factor receptor-associated periodic syndrome: new mutations in TNFRSF1A, ancestral origins, genotype-phenotype studies, and evidence for further genetic heterogeneity of periodic fevers."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The increased \nfrequency of P46L and R92Q among patients with periodic fever, as well as functional studies of \nTNFRSF1A, argue that these are low-penetrance mutations rather than benign \npolymorphisms."
    explanation: Aksentijevich et al. established R92Q and P46L as low-penetrance TNFRSF1A variants.
  - reference: PMID:11443543
    reference_title: "The tumor-necrosis-factor receptor-associated periodic syndrome: new mutations in TNFRSF1A, ancestral origins, genotype-phenotype studies, and evidence for further genetic heterogeneity of periodic fevers."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Genotype-phenotype studies identified, as carriers of cysteine mutations, 13 of \n14 patients with TRAPS and amyloidosis and indicated a lower penetrance of TRAPS \nsymptoms in individuals with noncysteine mutations."
    explanation: Cysteine-disrupting variants are strongly associated with amyloidosis and higher penetrance.
variants:
- name: R92Q
  description: >-
    Common low-penetrance TNFRSF1A variant (legacy nomenclature; c.362G>A) present
    in approximately 1% of control chromosomes. It behaves like the wild-type
    receptor in cell-biological assays and is associated with a milder phenotype
    and rare progression to amyloidosis; it is best regarded as a reduced-penetrance
    susceptibility/risk allele rather than a fully pathogenic variant.
  gene:
    preferred_term: TNFRSF1A
  clinical_significance: UNCERTAIN_SIGNIFICANCE
  evidence:
  - reference: PMID:11443543
    reference_title: "The tumor-necrosis-factor receptor-associated periodic syndrome: new mutations in TNFRSF1A, ancestral origins, genotype-phenotype studies, and evidence for further genetic heterogeneity of periodic fevers."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "two substitutions (P46L and R92Q) present \nin approximately 1% of control chromosomes."
    explanation: R92Q and P46L are present in approximately 1% of control chromosomes, consistent with a low-penetrance susceptibility allele.
- name: P46L
  description: >-
    Common low-penetrance TNFRSF1A variant present in approximately 1% of control
    chromosomes, enriched in individuals of African ancestry, associated with a
    milder TRAPS-like phenotype; a reduced-penetrance susceptibility/risk allele.
  gene:
    preferred_term: TNFRSF1A
  clinical_significance: UNCERTAIN_SIGNIFICANCE
  evidence:
  - reference: PMID:11443543
    reference_title: "The tumor-necrosis-factor receptor-associated periodic syndrome: new mutations in TNFRSF1A, ancestral origins, genotype-phenotype studies, and evidence for further genetic heterogeneity of periodic fevers."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "two substitutions (P46L and R92Q) present \nin approximately 1% of control chromosomes."
    explanation: P46L is one of the two common low-penetrance TNFRSF1A substitutions.
- name: T50M
  description: >-
    High-penetrance structural TNFRSF1A variant occurring at a CpG hotspot,
    strongly associated with persistent disease and AA amyloidosis.
  gene:
    preferred_term: TNFRSF1A
  clinical_significance: PATHOGENIC
  evidence:
  - reference: PMID:23965844
    reference_title: "The phenotype of TNF receptor-associated autoinflammatory syndrome (TRAPS) at presentation: a series of 158 cases from the Eurofever/EUROTRAPS international registry."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The most \ncommon TNFRSF1A variant was R92Q (34% of cases), followed by T50M (10%)."
    explanation: T50M was the second most common variant (10%) in the Eurofever/EUROTRAPS registry.
pathophysiology:
- name: TNFRSF1A Misfolding and ER Retention
  description: >-
    Pathogenic TNFRSF1A variants, especially cysteine-residue substitutions that
    disrupt conserved extracellular disulfide bonds, cause misfolding of the TNFR1
    protein. The mutant receptor forms abnormal disulfide-linked oligomers, fails
    to bind TNF, and is retained intracellularly in the endoplasmic reticulum
    rather than trafficking to the cell surface, distinguishing the mechanism from
    a simple loss of the soluble TNF-decoy receptor.
  gene:
    preferred_term: TNFRSF1A
  cell_types:
  - preferred_term: monocyte
    term:
      id: CL:0000576
      label: monocyte
  biological_processes:
  - preferred_term: response to endoplasmic reticulum stress
    term:
      id: GO:0034976
      label: response to endoplasmic reticulum stress
    modifier: INCREASED
  - preferred_term: ERAD pathway
    term:
      id: GO:0036503
      label: ERAD pathway
  evidence:
  - reference: PMID:16684962
    reference_title: "Abnormal disulfide-linked oligomerization results in ER retention and altered signaling by TNFR1 mutants in TNFR1-associated periodic fever syndrome (TRAPS)."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Instead, TRAPS mutant TNFR1 formed abnormal \ndisulfide-linked oligomers that failed to interact with wild-type TNFR1 \nmolecules through the preligand assembly domain (PLAD)"
    explanation: Lobito et al. (transfected cells) demonstrated that TRAPS-mutant TNFR1 forms abnormal disulfide-linked oligomers.
  - reference: PMID:16684962
    reference_title: "Abnormal disulfide-linked oligomerization results in ER retention and altered signaling by TNFR1 mutants in TNFR1-associated periodic fever syndrome (TRAPS)."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "TRAPS mutant TNFR1 molecules were retained \nintracellularly and colocalized with endoplasmic reticulum (ER) markers."
    explanation: In a mouse knock-in model and transfected cells, mutant TNFR1 was retained in the ER, supporting the misfolding/ER-retention model.
  downstream:
  - target: Enhanced Innate Cytokine Signaling
    causal_link_type: DIRECT
    description: >-
      ER retention of misfolded TNFR1 drives ER stress and elevated mitochondrial
      reactive oxygen species, lowering the threshold for innate immune activation
      and amplifying pro-inflammatory cytokine production.
    evidence:
    - reference: PMID:21282379
      reference_title: "Mitochondrial reactive oxygen species promote production of proinflammatory cytokines and are elevated in TNFR1-associated periodic syndrome (TRAPS)."
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: "We find elevated baseline ROS in \nboth mouse embryonic fibroblasts and human immune cells harboring \nTRAPS-associated TNFR1 mutations."
      explanation: Bulua et al. found elevated baseline reactive oxygen species in human immune cells harboring TRAPS mutations, linking ER-retained mutant receptor to enhanced inflammatory signaling.
- name: Enhanced Innate Cytokine Signaling
  description: >-
    Misfolded ER-retained TNFR1 raises mitochondrial reactive oxygen species,
    which potentiate MAPK signaling and the LPS-driven production of a broad set of
    pro-inflammatory cytokines (IL-1 beta, IL-6, and TNF) by monocytes and
    macrophages. This enhanced innate immune responsiveness, rather than loss of
    TNF decoy function, drives the autoinflammatory state.
  cell_types:
  - preferred_term: monocyte
    term:
      id: CL:0000576
      label: monocyte
  - preferred_term: macrophage
    term:
      id: CL:0000235
      label: macrophage
  - preferred_term: neutrophil
    term:
      id: CL:0000775
      label: neutrophil
  biological_processes:
  - preferred_term: reactive oxygen species metabolic process
    term:
      id: GO:0072593
      label: reactive oxygen species metabolic process
    modifier: INCREASED
  - preferred_term: interleukin-1 beta production
    term:
      id: GO:0032611
      label: interleukin-1 beta production
    modifier: INCREASED
  - preferred_term: interleukin-6 production
    term:
      id: GO:0032635
      label: interleukin-6 production
    modifier: INCREASED
  - preferred_term: tumor necrosis factor production
    term:
      id: GO:0032640
      label: tumor necrosis factor production
    modifier: INCREASED
  - preferred_term: inflammatory response
    term:
      id: GO:0006954
      label: inflammatory response
    modifier: INCREASED
  evidence:
  - reference: PMID:21282379
    reference_title: "Mitochondrial reactive oxygen species promote production of proinflammatory cytokines and are elevated in TNFR1-associated periodic syndrome (TRAPS)."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "A variety of antioxidants dampen LPS-induced \nMAPK phosphorylation and inflammatory cytokine production."
    explanation: Mitochondrial ROS potentiate MAPK signaling and LPS-induced cytokine production in TRAPS cells, the mechanistic basis of enhanced innate signaling.
  - reference: PMID:21282379
    reference_title: "Mitochondrial reactive oxygen species promote production of proinflammatory cytokines and are elevated in TNFR1-associated periodic syndrome (TRAPS)."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "TNFR1 mutant cells exhibit altered mitochondrial function with enhanced oxidative \ncapacity and mitochondrial ROS generation"
    explanation: Mouse embryonic fibroblasts harboring TRAPS mutations show enhanced mitochondrial ROS generation driving the inflammatory phenotype.
  downstream:
  - target: Systemic Autoinflammation
    causal_link_type: DIRECT
    description: >-
      Amplified IL-1 beta, IL-6, and TNF secretion drives recurrent systemic
      inflammatory attacks of fever, serositis, myalgia, and rash.
    evidence:
    - reference: PMID:29768139
      reference_title: "Canakinumab for the Treatment of Autoinflammatory Recurrent Fever Syndromes."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "45% versus 8% of \nthose with TRAPS (P=0.006)."
      explanation: >-
        The clinical efficacy of IL-1 beta blockade (canakinumab) in resolving and
        preventing TRAPS flares demonstrates that IL-1 beta is a dominant downstream
        effector driving the autoinflammatory attacks.
- name: Systemic Autoinflammation
  description: >-
    Recurrent, prolonged sterile inflammatory attacks affecting multiple systems:
    fever, sterile peritonitis, migratory myalgia with overlying rash, periorbital
    edema, conjunctivitis, arthralgia, and serositis, accompanied by a marked
    acute-phase response.
  cell_types:
  - preferred_term: neutrophil
    term:
      id: CL:0000775
      label: neutrophil
  - preferred_term: monocyte
    term:
      id: CL:0000576
      label: monocyte
  biological_processes:
  - preferred_term: inflammatory response
    term:
      id: GO:0006954
      label: inflammatory response
    modifier: INCREASED
  locations:
  - preferred_term: peritoneum
    term:
      id: UBERON:0002358
      label: peritoneum
  - preferred_term: skeletal muscle tissue
    term:
      id: UBERON:0001134
      label: skeletal muscle tissue
  evidence:
  - reference: PMID:11443543
    reference_title: "The tumor-necrosis-factor receptor-associated periodic syndrome: new mutations in TNFRSF1A, ancestral origins, genotype-phenotype studies, and evidence for further genetic heterogeneity of periodic fevers."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "which is characterized by attacks of fever, sterile peritonitis, arthralgia, myalgia, \nskin rash, and/or conjunctivitis; some patients also develop systemic \namyloidosis."
    explanation: TRAPS attacks involve fever, sterile peritonitis, arthralgia, myalgia, skin rash, and conjunctivitis.
  downstream:
  - target: AA Amyloidosis
    causal_link_type: DIRECT
    description: >-
      Chronic and subclinical inflammation between attacks sustains elevation of
      serum amyloid A, leading to deposition of AA amyloid fibrils, predominantly
      in the kidney, causing proteinuria and progressive renal failure.
    evidence:
    - reference: PMID:36375008
      reference_title: "TNF Receptor-Associated Periodic Fever Syndrome."
      supports: SUPPORT
      evidence_source: OTHER
      snippet: "Proteinuria \nand kidney failure occur in 80%-90% of affected individuals with amyloidosis"
      explanation: AA amyloidosis is the most severe sequela of TRAPS, causing proteinuria and kidney failure in 80-90% of affected individuals.
- name: AA Amyloidosis
  description: >-
    Reactive (AA) systemic amyloidosis arising from chronically elevated serum
    amyloid A, with renal-predominant amyloid fibril deposition leading to
    proteinuria, nephrotic syndrome, and progressive kidney failure. It is the
    principal organ-threatening, potentially fatal complication of TRAPS and is
    largely preventable with sustained suppression of inflammation.
  locations:
  - preferred_term: kidney
    term:
      id: UBERON:0002113
      label: kidney
  evidence:
  - reference: PMID:23965844
    reference_title: "The phenotype of TNF receptor-associated autoinflammatory syndrome (TRAPS) at presentation: a series of 158 cases from the Eurofever/EUROTRAPS international registry."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "AA amyloidosis has \ndeveloped in 16 (10%) patients at a median age of 43 years."
    explanation: AA amyloidosis developed in 10% of the Eurofever/EUROTRAPS registry patients at a median age of 43 years.
phenotypes:
- category: Systemic
  name: Recurrent Prolonged Fever
  frequency: VERY_FREQUENT
  diagnostic: true
  notes: >-
    Hallmark of TRAPS; attacks characteristically last 5-25 days (often more than
    one week), longer than the short attacks of FMF and MKD.
  phenotype_term:
    preferred_term: Recurrent fever
    term:
      id: HP:0001954
      label: Recurrent fever
    temporality: PROLONGED
  evidence:
  - reference: PMID:23965844
    reference_title: "The phenotype of TNF receptor-associated autoinflammatory syndrome (TRAPS) at presentation: a series of 158 cases from the Eurofever/EUROTRAPS international registry."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Attacks were recurrent in 88% and the commonest features associated with the pathogenic variants were \nfever (88%)"
    explanation: Fever was present in 88% of registry patients (VERY_FREQUENT), with recurrent attacks in 88%.
  - reference: PMID:36375008
    reference_title: "TNF Receptor-Associated Periodic Fever Syndrome."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "episodes of inflammation typically occurring every \nfour to six weeks and lasting between five and 25 days."
    explanation: GeneReviews documents the characteristically prolonged 5-25 day attacks.
- category: Musculoskeletal
  name: Myalgia
  frequency: VERY_FREQUENT
  notes: >-
    Characteristically migratory, due to underlying monocytic fasciitis, often
    with overlying erythematous rash.
  phenotype_term:
    preferred_term: Myalgia
    term:
      id: HP:0003326
      label: Myalgia
  evidence:
  - reference: PMID:23965844
    reference_title: "The phenotype of TNF receptor-associated autoinflammatory syndrome (TRAPS) at presentation: a series of 158 cases from the Eurofever/EUROTRAPS international registry."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "fever (88%), limb pain (85%), abdominal pain (74%), rash (63%) and eye \nmanifestations (45%)"
    explanation: Limb pain (encompassing myalgia) was present in 85% of registry patients (VERY_FREQUENT).
- category: Gastrointestinal
  name: Abdominal Pain
  frequency: FREQUENT
  notes: Sterile peritonitis; may mimic a surgical abdomen.
  phenotype_term:
    preferred_term: Abdominal pain
    term:
      id: HP:0002027
      label: Abdominal pain
  evidence:
  - reference: PMID:23965844
    reference_title: "The phenotype of TNF receptor-associated autoinflammatory syndrome (TRAPS) at presentation: a series of 158 cases from the Eurofever/EUROTRAPS international registry."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "fever (88%), limb pain (85%), abdominal pain (74%), rash (63%) and eye \nmanifestations (45%)"
    explanation: Abdominal pain was present in 74% of registry patients (FREQUENT).
- category: Integumentary
  name: Migratory Erythematous Rash
  frequency: FREQUENT
  notes: Migratory erythematous rash that characteristically overlies the painful muscle group.
  phenotype_term:
    preferred_term: Migratory erythematous rash
    term:
      id: HP:0033622
      label: Migratory erythematous plaque
  evidence:
  - reference: PMID:23965844
    reference_title: "The phenotype of TNF receptor-associated autoinflammatory syndrome (TRAPS) at presentation: a series of 158 cases from the Eurofever/EUROTRAPS international registry."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "fever (88%), limb pain (85%), abdominal pain (74%), rash (63%) and eye \nmanifestations (45%)"
    explanation: Rash was present in 63% of registry patients (FREQUENT); in TRAPS it is characteristically migratory and overlies the painful muscle.
- category: Head and Neck
  name: Periorbital Edema
  frequency: FREQUENT
  notes: Highly characteristic ocular sign of TRAPS.
  phenotype_term:
    preferred_term: Periorbital edema
    term:
      id: HP:0100539
      label: Periorbital edema
  evidence:
  - reference: PMID:23965844
    reference_title: "The phenotype of TNF receptor-associated autoinflammatory syndrome (TRAPS) at presentation: a series of 158 cases from the Eurofever/EUROTRAPS international registry."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Children were more likely than adults to present with \nlymphadenopathy, periorbital oedema and abdominal pains."
    explanation: Periorbital edema is a characteristic eye manifestation of TRAPS, particularly in children.
- category: Head and Neck
  name: Conjunctivitis
  frequency: FREQUENT
  notes: Ocular inflammation; part of the characteristic eye manifestations of TRAPS.
  phenotype_term:
    preferred_term: Conjunctivitis
    term:
      id: HP:0000509
      label: Conjunctivitis
  evidence:
  - reference: PMID:23965844
    reference_title: "The phenotype of TNF receptor-associated autoinflammatory syndrome (TRAPS) at presentation: a series of 158 cases from the Eurofever/EUROTRAPS international registry."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "fever (88%), limb pain (85%), abdominal pain (74%), rash (63%) and eye \nmanifestations (45%)"
    explanation: Eye manifestations, including conjunctivitis, were present in 45% of registry patients (FREQUENT).
  - reference: PMID:11443543
    reference_title: "The tumor-necrosis-factor receptor-associated periodic syndrome: new mutations in TNFRSF1A, ancestral origins, genotype-phenotype studies, and evidence for further genetic heterogeneity of periodic fevers."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "attacks of fever, sterile peritonitis, arthralgia, myalgia, \nskin rash, and/or conjunctivitis"
    explanation: Conjunctivitis is among the defining manifestations of TRAPS attacks.
- category: Musculoskeletal
  name: Arthralgia
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Arthralgia
    term:
      id: HP:0002829
      label: Arthralgia
  evidence:
  - reference: PMID:11443543
    reference_title: "The tumor-necrosis-factor receptor-associated periodic syndrome: new mutations in TNFRSF1A, ancestral origins, genotype-phenotype studies, and evidence for further genetic heterogeneity of periodic fevers."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "attacks of fever, sterile peritonitis, arthralgia, myalgia, \nskin rash, and/or conjunctivitis"
    explanation: Arthralgia is a defining manifestation of TRAPS attacks.
- category: Head and Neck
  name: Lymphadenopathy
  notes: More common in children at presentation.
  phenotype_term:
    preferred_term: Lymphadenopathy
    term:
      id: HP:0002716
      label: Lymphadenopathy
  evidence:
  - reference: PMID:23965844
    reference_title: "The phenotype of TNF receptor-associated autoinflammatory syndrome (TRAPS) at presentation: a series of 158 cases from the Eurofever/EUROTRAPS international registry."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Children were more likely than adults to present with \nlymphadenopathy, periorbital oedema and abdominal pains."
    explanation: Lymphadenopathy is a recognized TRAPS manifestation, more frequent in children.
- category: Renal
  name: AA Amyloidosis
  frequency: OCCASIONAL
  notes: Late complication; renal-predominant AA amyloidosis, the major cause of TRAPS mortality.
  phenotype_term:
    preferred_term: Amyloidosis
    term:
      id: HP:0011034
      label: Amyloid deposition
  evidence:
  - reference: PMID:23965844
    reference_title: "The phenotype of TNF receptor-associated autoinflammatory syndrome (TRAPS) at presentation: a series of 158 cases from the Eurofever/EUROTRAPS international registry."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "AA amyloidosis has \ndeveloped in 16 (10%) patients at a median age of 43 years."
    explanation: AA amyloidosis developed in 10% of registry patients (OCCASIONAL).
- category: Renal
  name: Proteinuria
  notes: Manifestation of renal AA amyloidosis; the basis for renal surveillance in TRAPS.
  phenotype_term:
    preferred_term: Proteinuria
    term:
      id: HP:0000093
      label: Proteinuria
  evidence:
  - reference: PMID:36375008
    reference_title: "TNF Receptor-Associated Periodic Fever Syndrome."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "Proteinuria \nand kidney failure occur in 80%-90% of affected individuals with amyloidosis"
    explanation: Proteinuria and kidney failure occur in 80-90% of TRAPS patients who develop amyloidosis.
biochemical:
- name: C-Reactive Protein
  presence: Elevated
  notes: Acute-phase reactant elevated during attacks and often somewhat between attacks.
  biomarker_term:
    preferred_term: Elevated C-reactive protein
    term:
      id: HP:0011227
      label: Elevated circulating C-reactive protein concentration
  evidence:
  - reference: PMID:36375008
    reference_title: "TNF Receptor-Associated Periodic Fever Syndrome."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "acute-phase reactants such as C-reactive protein (CRP), erythrocyte \nsedimentation rate (ESR), and serum amyloid A are typically elevated."
    explanation: CRP, ESR, and serum amyloid A are elevated during TRAPS flares.
- name: Erythrocyte Sedimentation Rate
  presence: Elevated
  notes: Acute-phase reactant elevated during flares.
  biomarker_term:
    preferred_term: Elevated erythrocyte sedimentation rate
    term:
      id: HP:0003565
      label: Elevated erythrocyte sedimentation rate
  evidence:
  - reference: PMID:36375008
    reference_title: "TNF Receptor-Associated Periodic Fever Syndrome."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "acute-phase reactants such as C-reactive protein (CRP), erythrocyte \nsedimentation rate (ESR), and serum amyloid A are typically elevated."
    explanation: ESR is elevated as part of the TRAPS acute-phase response.
- name: Serum Amyloid A
  presence: Elevated
  notes: >-
    Elevated during flares and, importantly, often persistently between attacks;
    chronic elevation drives AA amyloidosis and is the key surveillance marker.
  evidence:
  - reference: PMID:36375008
    reference_title: "TNF Receptor-Associated Periodic Fever Syndrome."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "acute-phase reactants stabilize between flares but may remain somewhat elevated \neven in the absence of clinical symptoms."
    explanation: Persistent elevation of acute-phase reactants including serum amyloid A between flares drives amyloidosis risk.
- name: Soluble TNF Receptor 1
  presence: Reduced
  notes: >-
    Plasma soluble TNFR1 levels were classically found to be approximately half
    normal; reduced receptor shedding is a historical laboratory clue but is
    neither sensitive nor specific and has been superseded by genetic testing.
  evidence:
  - reference: PMID:10199409
    reference_title: "Germline mutations in the extracellular domains of the 55 kDa TNF receptor, TNFR1, define a family of dominantly inherited autoinflammatory syndromes."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Soluble plasma TNFR1 levels in patients were approximately half normal."
    explanation: McDermott et al. found soluble plasma TNFR1 levels approximately half normal in TRAPS patients.
diagnosis:
- name: Genetic Testing
  results: Identifies a heterozygous pathogenic TNFRSF1A variant
  evidence:
  - reference: PMID:36375008
    reference_title: "TNF Receptor-Associated Periodic Fever Syndrome."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "The diagnosis of TRAPS is established in a proband with at \nleast one suggestive clinical feature and a heterozygous pathogenic (or likely \npathogenic) variant in TNFRSF1A identified by molecular genetic testing."
    explanation: GeneReviews establishes that diagnosis requires a heterozygous pathogenic TNFRSF1A variant plus a suggestive clinical feature.
- name: Acute-Phase Reactants
  presence: Elevated
  markers: CRP, ESR, SAA
  evidence:
  - reference: PMID:36375008
    reference_title: "TNF Receptor-Associated Periodic Fever Syndrome."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "acute-phase reactants such as C-reactive protein (CRP), erythrocyte \nsedimentation rate (ESR), and serum amyloid A are typically elevated."
    explanation: Elevated CRP, ESR, and SAA during flares support the diagnosis and track disease activity.
differential_diagnoses:
- name: Familial Mediterranean Fever
  distinguishing_features:
  - FMF is autosomal recessive (MEFV), whereas TRAPS is autosomal dominant
  - FMF attacks are short (1-3 days) and colchicine-responsive, in contrast to the prolonged (5-25 day), colchicine-unresponsive attacks of TRAPS
- name: Mevalonate Kinase Deficiency
  distinguishing_features:
  - MKD (hyper-IgD syndrome, MVK) is autosomal recessive with infantile onset, cervical adenitis, and elevated IgD
  - MKD attacks are shorter than the prolonged 5-25 day attacks of TRAPS
- name: Cryopyrin-Associated Periodic Syndromes
  distinguishing_features:
  - CAPS (NLRP3) features urticarial rash and, in severe forms, sensorineural hearing loss and CNS involvement
  - CAPS lacks the migratory myalgia rash, periorbital edema, and prolonged attacks characteristic of TRAPS
treatments:
- name: Anakinra
  description: >-
    Recombinant IL-1 receptor antagonist; a first-line IL-1 inhibitor for TRAPS
    that rapidly controls attacks and acute-phase inflammation and helps prevent
    AA amyloidosis.
  therapeutic_modality: PROTEIN_REPLACEMENT
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
  target_mechanisms:
  - target: Enhanced Innate Cytokine Signaling
    treatment_effect: INHIBITS
    description: Anakinra blocks IL-1 receptor signaling, neutralizing the amplified IL-1 output of the enhanced innate cytokine signaling node.
  evidence:
  - reference: PMID:36375008
    reference_title: "TNF Receptor-Associated Periodic Fever Syndrome."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "Interleukin-1 (IL-1) inhibitors \n(anakinra or canakinumab) are considered first-line therapies."
    explanation: GeneReviews designates IL-1 inhibitors anakinra and canakinumab as first-line therapy for TRAPS.
- name: Canakinumab
  description: >-
    Anti-IL-1 beta monoclonal antibody; the only biologic with a pivotal randomized
    controlled trial and regulatory approval for TRAPS, controlling and preventing
    flares and helping to prevent AA amyloidosis.
  therapeutic_modality: MONOCLONAL_ANTIBODY
  treatment_term:
    preferred_term: anti-IL-1 beta monoclonal antibody
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: monoclonal antibody
      term:
        id: NCIT:C20401
        label: Monoclonal Antibody
  target_mechanisms:
  - target: Enhanced Innate Cytokine Signaling
    treatment_effect: INHIBITS
    description: Canakinumab neutralizes IL-1 beta, the dominant downstream effector amplified in the enhanced innate cytokine signaling node.
  evidence:
  - reference: PMID:29768139
    reference_title: "Canakinumab for the Treatment of Autoinflammatory Recurrent Fever Syndromes."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "canakinumab was effective in controlling and \npreventing flares in patients with colchicine-resistant familial Mediterranean \nfever, mevalonate kinase deficiency, and TRAPS."
    explanation: The phase 3 CLUSTER randomized controlled trial showed canakinumab effective in controlling and preventing TRAPS flares.
- name: Etanercept
  description: >-
    Soluble TNFR2-Fc fusion protein historically used in TRAPS; it reduces symptoms
    and acute-phase reactants in a dose-dependent manner but does not completely
    normalize them, and long-term adherence is poor. Note that, unlike etanercept,
    monoclonal anti-TNF antibodies (infliximab, adalimumab) can paradoxically worsen
    TRAPS and are generally avoided.
  therapeutic_modality: PROTEIN_REPLACEMENT
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: etanercept
      term:
        id: CHEBI:4875
        label: etanercept
  evidence:
  - reference: PMID:22006113
    reference_title: "Efficacy of etanercept in the tumor necrosis factor receptor-associated periodic syndrome: a prospective, open-label, dose-escalation study."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Etanercept reduces symptoms and serum levels of inflammatory markers \nof TRAPS in a dose-dependent manner, but does not completely normalize symptoms \nor acute-phase reactant levels."
    explanation: Etanercept reduces TRAPS symptoms and inflammatory markers dose-dependently but incompletely.
- name: Corticosteroids
  description: >-
    High-dose corticosteroids can attenuate acute attacks but are not sufficient
    for long-term management or for preventing amyloidosis, and chronic use causes
    toxicity.
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: prednisone
      term:
        id: CHEBI:8382
        label: prednisone
  evidence:
  - reference: PMID:36375008
    reference_title: "TNF Receptor-Associated Periodic Fever Syndrome."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "The use of corticosteroids may be useful as \nneeded during an acute attack but is not sufficient for long-term management or \nfor preventing amyloidosis."
    explanation: GeneReviews notes corticosteroids help acute attacks but are insufficient for long-term control or amyloidosis prevention.
- name: Genetic Counseling
  description: >-
    Counseling regarding autosomal dominant transmission with a 50% risk to
    offspring, variable expressivity, and the interpretive challenges of the
    low-penetrance R92Q and P46L variants.
  treatment_term:
    preferred_term: Genetic Counseling
    term:
      id: NCIT:C15240
      label: Genetic Counseling
  evidence:
  - reference: PMID:23965844
    reference_title: "The phenotype of TNF receptor-associated autoinflammatory syndrome (TRAPS) at presentation: a series of 158 cases from the Eurofever/EUROTRAPS international registry."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "A family history was present in 19% of patients with R92Q and 64% of \nthose with other variants."
    explanation: Variant-dependent penetrance and family history support the need for genetic counseling in TRAPS families.
clinical_trials:
- name: NCT02059291
  phase: PHASE_III
  status: COMPLETED
  description: >-
    CLUSTER trial: randomized, double-blind, placebo-controlled study of
    canakinumab in patients with hereditary periodic fevers (TRAPS, HIDS/MKD, or
    colchicine-resistant FMF), with randomized withdrawal and open-label long-term
    treatment epochs.
  target_phenotypes:
  - preferred_term: Recurrent fever
    term:
      id: HP:0001954
      label: Recurrent fever
  evidence:
  - reference: clinicaltrials:NCT02059291
    reference_title: "A Randomized, Double-blind, Placebo Controlled Study of Canakinumab in Patients With Hereditary Periodic Fevers (TRAPS, HIDS, or crFMF), With Subsequent Randomized Withdrawal/Dosing Frequency Reduction and Open-label Long-term Treatment Epochs"
    supports: SUPPORT
    snippet: "This study is to determine whether canakinumab is able to induce and maintain a clinically meaningful reduction of disease activity in participants with Hereditary Periodic Fevers (HPF) compared to placebo."
    explanation: The CLUSTER trial evaluated canakinumab for disease-activity reduction in hereditary periodic fevers including TRAPS.
classifications:
  harrisons_chapter:
  - classification_value: IMMUNE_RHEUMATOLOGIC
  - classification_value: GENETICS_ENVIRONMENT_DISEASE
discussions:
- discussion_id: traps_mouse_model_mismatch
  kind: HUMAN_MODEL_MISMATCH
  status: OPEN
  prompt: >-
    Do the TNFR1 knock-in mouse models of TRAPS reproduce the full human
    periodic-fever and AA-amyloidosis phenotype, or only the cellular/molecular
    phenotype?
  attaches_to:
  - pathophysiology#TNFRSF1A Misfolding and ER Retention
  rationale: >-
    Mouse knock-in models and patient-derived cells faithfully reproduce the
    molecular phenotype of TRAPS (ER retention of mutant TNFR1, elevated
    mitochondrial ROS, and hyper-responsive innate cytokine secretion). However,
    the dramatic recurrent multi-organ human attacks and progression to AA
    amyloidosis are incompletely captured in animal models, so translational
    validity for the clinical syndrome (as opposed to the cell-biological
    mechanism) remains an open question.
  proposed_experiments:
  - experiment_id: exp_traps_knockin_natural_history
    name: Longitudinal natural-history phenotyping of TNFR1 knock-in mice
    description: >-
      Perform longitudinal phenotyping of TNFR1 knock-in mice for spontaneous
      febrile and serositis attacks and for renal AA amyloid deposition under
      inflammatory challenge, to test whether the clinical periodic-fever and
      amyloidosis phenotype, not just the cellular phenotype, is recapitulated.
notes: >-
  TRAPS differentiation from siblings: in contrast to familial Mediterranean fever
  (autosomal recessive MEFV, short 1-3 day colchicine-responsive attacks) and
  mevalonate kinase deficiency (autosomal recessive MVK, infantile onset with
  cervical adenitis and elevated IgD), TRAPS is autosomal dominant with
  characteristically prolonged attacks (5-25 days), periorbital edema, and
  migratory erythematous rash overlying myalgia. Colchicine is largely ineffective
  in TRAPS.

📚

References & Deep Research

References

1

PMID:36375008

TNF Receptor-Associated Periodic Fever Syndrome.

No top-level findings curated for this source.

Deep Research

1

Claude Code ▸

1. Disease Information

claude-haiku-4-5-20251001, claude-opus-4-8[1m] 12 citations 2026-06-30T09:10:05.631925

1. Disease Information

Overview. TNF receptor-associated periodic syndrome (TRAPS) is the prototypic autosomal-dominant monogenic autoinflammatory disease (hereditary periodic fever syndrome), caused by heterozygous mutations in TNFRSF1A, the gene encoding the 55-kDa type 1 receptor for tumor necrosis factor (TNFR1/p55/CD120a). Clinically it is defined by recurrent, self-limited inflammatory attacks — fever, migratory myalgia with overlying rash, abdominal pain (sterile peritonitis), periorbital edema, conjunctivitis, and arthralgia — that characteristically last longer than the attacks of other periodic fevers (often 1–3 weeks), separating it from familial Mediterranean fever (FMF, attacks 1–3 days) and the cryopyrinopathies. The most feared long-term complication is systemic AA (reactive) amyloidosis.

Think of TNFR1 here like a smoke detector wired backwards: instead of quietly waiting at the cell surface for a real fire (TNF), the mutant receptor gets jammed inside the cell's "shipping department" and starts setting off the alarm on its own.

It was first delineated genetically in 1999, unifying several previously eponymous disorders — most famously "familial Hibernian fever" described in a large Irish/Scottish kindred — under a single molecular cause.

"In seven affected families, we found six different missense mutations of the 55 kDa TNF receptor (TNFR1), five of which disrupt conserved extracellular disulfide bonds. Soluble plasma TNFR1 levels in patients were approximately half normal." — McDermott et al., Cell 1999 (PMID:10199409)

Key identifiers: | Resource | Identifier | |---|---| | MONDO | MONDO:0019751 (TNF receptor associated periodic syndrome) | | OMIM | 142680 (TNF RECEPTOR-ASSOCIATED PERIODIC SYNDROME; TRAPS) | | Orphanet | ORPHA:32960 | | ICD-11 | 4A60.23 (Tumour necrosis factor receptor 1 associated periodic syndrome) | | ICD-10 | No dedicated code; coded under M04.1 (periodic fever syndromes) / D89.8 | | MeSH | No standalone descriptor; indexed under Hereditary Autoinflammatory Diseases (D056660) | | Gene (HGNC) | TNFRSF1A, hgnc:11916 |

Synonyms / alternative names: TRAPS; TNF receptor-associated periodic fever syndrome; Familial Hibernian fever (FHF); Hibernian fever; Autosomal dominant familial periodic fever; Familial periodic fever, autosomal dominant; TNFRSF1A-associated periodic syndrome; periodic fever, familial, autosomal dominant.

Data derivation: Disease-level knowledge here is aggregated from curated resources (OMIM, Orphanet, GeneReviews) and from patient-level cohort data, most notably the Eurofever/EUROTRAPS international registry (158 validated cases) — i.e., this is registry/cohort-aggregated rather than EHR-derived.

2. Etiology

Primary cause (genetic). TRAPS is monogenic: heterozygous gain-of-function/misfolding missense mutations in TNFRSF1A, located predominantly in the extracellular cysteine-rich domains (CRD1 and CRD2) of TNFR1. Mutations that disrupt conserved disulfide bonds (e.g., cysteine substitutions, T50M) confer the highest penetrance and severity.

Triggers of attacks (environmental/physiologic modifiers). Individual flares are often precipitated by physical or psychological stress, minor infection, trauma, fatigue, hormonal changes (menstruation), exercise, and vaccination — but the underlying disease is genetic, and these are flare triggers, not causes.

Risk factors - Genetic risk factors: - Causal/high-penetrance variants: cysteine substitutions (C30R, C43R, C52F, C88Y, etc.) and T50M — strongly associated with disease persistence into adulthood and amyloidosis. - Low-penetrance susceptibility variants: R92Q (c.362G>A; legacy nomenclature; corresponds to p.Arg121Gln with signal peptide) and P46L (p.Pro75Leu). These are common in the general population, behave as susceptibility/modifier alleles rather than fully penetrant disease alleles, and produce milder, sometimes self-limited phenotypes. In the Eurofever cohort, R92Q accounted for ~34% of cases and T50M ~10%, with family history present in only 19% of R92Q carriers vs 64% of those with other variants (Lachmann et al., PMID:23965844). - Family history: a first-degree affected relative is a major risk factor given autosomal-dominant transmission. - Environmental risk factors: No environmental exposure causes TRAPS; ethnicity influences variant frequency (R92Q and P46L vary by population — P46L is notably more frequent in individuals of West/sub-Saharan African ancestry).

Protective factors. None specifically established genetically. Effective continuous anti-inflammatory therapy is "protective" against the development of amyloidosis (see §11–12). No dietary or lifestyle protective factor is validated.

Gene–environment interactions. The clearest interaction is stress/infection/trauma acting on a genetically primed innate immune system to precipitate flares. For low-penetrance alleles (R92Q/P46L), phenotype is thought to emerge only with additional genetic or environmental "second hits," explaining incomplete penetrance.

3. Phenotypes

For each, I give type, characteristics, and a suggested HP term. Frequencies are drawn primarily from the Eurofever/EUROTRAPS registry (Lachmann 2014, PMID:23965844) and Aksentijevich 2001 (PMID:11443543, Am J Hum Genet 69:301–314 — verify exact digits before commit).

Phenotype	Type	Approx. frequency	Suggested HP term
Recurrent fever (hallmark; attacks often last 1–3 weeks)	Symptom/sign	~85–90%+ (near-defining)	HP:0001954 Recurrent fever
Myalgia (characteristically migratory, due to monocytic fasciitis)	Symptom	~60–80%	HP:0003326 Myalgia
Abdominal pain (sterile peritonitis; may mimic surgical abdomen)	Symptom	~70–90%	HP:0002027 Abdominal pain
Skin rash — erythematous, often migratory, overlying the painful muscle group	Sign	~60–80%	HP:0000988 Skin rash / HP:0010783 Erythema
Periorbital edema (highly characteristic of TRAPS)	Sign	~30–50%	HP:0100539 Periorbital edema
Conjunctivitis / ocular involvement	Sign	~20–45%	HP:0000509 Conjunctivitis
Arthralgia / arthritis	Symptom/sign	~40–60%	HP:0002829 Arthralgia
Chest pain / pleuritis (serositis)	Symptom/sign	~20–40%	HP:0002102 Pleuritis / Abnormality of the pleura
Headache	Symptom	~40–70%	HP:0002315 Headache
Lymphadenopathy	Sign	variable	HP:0002716 Lymphadenopathy
Splenomegaly	Sign	variable	HP:0001744 Splenomegaly
Scrotal/testicular pain	Symptom	occasional (males)	HP:0030241 (scrotal pain — verify)
AA amyloidosis (renal-predominant) — late complication	Lab/clinical	~10–25% lifetime (untreated; higher with cysteine variants)	HP:0011034 Amyloidosis; HP:0000093 Proteinuria; HP:0000100 Nephrotic syndrome

Laboratory abnormalities (acute-phase reaction during flares): | Lab phenotype | Suggested HP term | |---|---| | Elevated C-reactive protein | HP:0011227 Increased C-reactive protein level | | Elevated ESR | HP:0003565 Elevated erythrocyte sedimentation rate | | Leukocytosis / neutrophilia | HP:0001974 Leukocytosis | | Reactive thrombocytosis | HP:0001894 Thrombocytosis | | Anemia of chronic disease | HP:0001903 Anemia | | Elevated serum amyloid A (SAA) | (use elevated acute-phase reactant) | | Polyclonal hypergammaglobulinemia / elevated IgD (modest) | HP:0010702 (IgD elevation — verify) |

Phenotype characteristics: - Onset: typically childhood (median ~4 years) but a wide range, with adult-onset (even after age 50) well documented, especially for low-penetrance variants. - Severity: variable, strongly genotype-influenced — cysteine/T50M variants severe; R92Q/P46L mild. - Progression: episodic/recurrent with symptom-free intervals; attacks recur every ~4–6 weeks, lasting (per GeneReviews) "between five and 25 days." Subclinical inflammation can persist between attacks, driving amyloidosis. - Quality-of-life impact: Recurrent prolonged attacks cause significant school/work absenteeism, chronic pain, fatigue, and impaired daily functioning; amyloidosis can progress to chronic kidney disease and dialysis dependence. (No TRAPS-specific validated QoL instrument; generic SF-36/EQ-5D and the AIDAI [Autoinflammatory Diseases Activity Index] are used in autoinflammatory cohorts.)

4. Genetic / Molecular Information

Causal gene. TNFRSF1A (TNF receptor superfamily member 1A), HGNC: hgnc:11916, located at chromosome 12p13.31; OMIM gene 142680; encodes TNFR1 (p55, CD120a), UniProt P19438. NCBI Gene ID 7132; Ensembl ENSG00000067182.

Pathogenic variants. - Location: clustered in exons 2–4, encoding the extracellular cysteine-rich domains CRD1 and CRD2. - Variant type/class: predominantly missense; a large fraction are cysteine substitutions that abolish one of the conserved disulfide bonds essential for correct folding of the CRDs. Splice and small in-frame changes are rare. No large deletions or whole-gene CNVs are characteristic — this is a coding-missense disease. - Representative high-penetrance variants: C30R, C30S, C33Y, C43R, T50M, C52F, C70R/C70Y, C88R/C88Y, etc. - Low-penetrance variants: R92Q (c.362G>A) and P46L — present at appreciable allele frequency in gnomAD (R92Q ~1% in some populations; P46L higher in African-ancestry groups), consistent with reduced penetrance and a susceptibility-allele model. - Origin: germline (autosomal dominant); de novo mutations occur. No somatic mechanism. - Functional consequence: Mechanistically a misfolding / aberrant gain-of-function (NOT simple haploinsufficiency or classical loss of TNF signaling) — see §6. Original "shedding hypothesis" (impaired cleavage of TNFR1 from the cell surface leaving membrane receptor to signal unopposed) has been superseded/complemented by the misfolding/ER-retention model.

Aksentijevich et al. confirmed and expanded the mutational spectrum and population genetics: "mutations in the extracellular domain of the 55-kD tumor-necrosis factor (TNF) receptor (TNFRSF1A) define TRAPS" (PMID:11443543, Am J Hum Genet 2001 — verify digits).

Variant classification (ACMG/AMP). Cysteine and T50M variants are generally curated Pathogenic/Likely pathogenic in ClinVar; R92Q and P46L are typically classified as "risk factor" / reduced-penetrance / conflicting rather than straightforwardly pathogenic.

Modifier genes. Not well defined. Genetic background and possibly other innate-immunity loci modulate penetrance, particularly for R92Q/P46L; co-inheritance with MEFV (FMF) variants has been reported to modify phenotype in individual cases.

Epigenetic information. No established disease-defining epigenetic signature. Inflammation-associated changes are secondary.

Chromosomal abnormalities. None characteristic — TRAPS is a single-nucleotide/missense disorder, not a structural/aneuploidy disorder.

5. Environmental Information

Environmental factors: No toxin, radiation, or pollutant is causal. Flares are precipitated by nonspecific stressors (see §2).
Lifestyle factors: Physical exertion, emotional stress, and fatigue are reported flare triggers; no lifestyle factor causes or cures the disease.
Infectious agents: No causative pathogen. Intercurrent infections can trigger flares and complicate the differential diagnosis, but TRAPS is sterile (non-infectious) autoinflammation; "sterile peritonitis" is a defining feature.

6. Mechanism / Pathophysiology

TRAPS sits at the intersection of TNF signaling, ER protein-folding quality control, mitochondrial ROS, and innate cytokine amplification. The current integrated model:

Causal chain (upstream → downstream):

Mutant TNFR1 misfolds because disulfide-bond–disrupting (cysteine) or destabilizing (T50M) substitutions prevent correct folding of the extracellular CRDs.
Misfolded receptor is retained in the endoplasmic reticulum rather than trafficking to the cell surface; it forms abnormal disulfide-linked oligomers that cannot engage wild-type receptor via the pre-ligand assembly domain (PLAD).

"TRAPS mutant TNFR1 molecules were retained intracellularly and colocalized with endoplasmic reticulum markers... The inflammatory phenotype of TRAPS may be due to consequences of mutant TNFR1 protein misfolding and ER retention." — Lobito et al., Blood 2006 (PMID:16684962)

ER stress / unfolded protein response (UPR) is activated by the accumulated misfolded receptor.
Elevated mitochondrial reactive oxygen species (mtROS) result, lowering the threshold for innate immune activation and enhancing pro-inflammatory cytokine production (especially in response to LPS).

"Mitochondrial ROS... promote production of proinflammatory cytokines and are elevated in TNFR1-associated periodic syndrome (TRAPS)... ROS generated by mitochondrial respiration are important for... the enhanced responsiveness to LPS seen in cells from patients with TRAPS." — Bulua et al., J Exp Med 2011 (PMID:21282379)

Constitutive/augmented activation of NF-κB and MAPK (JNK/p38) signaling, plus defective autophagy of mutant receptor, sustains an inflammatory state. Some surface-retained mutant receptor signals in a ligand-independent manner.
Amplified secretion of IL-1β (and IL-6, TNF) drives the clinical attacks. The dramatic efficacy of IL-1 blockade is the clinical proof that IL-1β is the dominant downstream effector (CLUSTER trial, §12).
Chronic/subclinical inflammation → sustained elevation of serum amyloid A (SAA) → AA amyloid fibril deposition, predominantly in the kidney (renal amyloidosis → proteinuria/nephrotic syndrome → renal failure).

A "concerted action" of wild-type and mutant receptors enhancing inflammation has also been proposed (Simon et al., PNAS 2010 — PMID ~20133695; verify before commit).

Molecular pathways (suggested annotations): - TNF-mediated signaling pathway — GO:0033209 - I-κB kinase/NF-κB signaling — GO:0007249 - MAPK cascade — GO:0000165 - Response to endoplasmic reticulum stress / UPR — GO:0034976; cellular response to unfolded protein — GO:0034620 - Reactive oxygen species metabolic process — GO:0072593 - Inflammatory response — GO:0006954 - Interleukin-1 beta production — GO:0032611 - Autophagy — GO:0006914 (impaired clearance of mutant receptor) - Protein folding — GO:0006457

Cellular processes: ER-stress signaling, mitochondrial ROS generation, NLRP3 inflammasome priming/activation, defective autophagy, ligand-independent receptor signaling, enhanced innate cytokine secretion.

Protein dysfunction: misfolding + aggregation + intracellular (ER) retention of TNFR1 → aberrant gain of pro-inflammatory function. UniProt P19438; structural basis in the cysteine-rich TNFR ectodomain (PDB structures of TNFR1 ectodomain, e.g., 1NCF/1EXT).

Immune system involvement: This is an innate-immune (autoinflammatory) disease — monocytes/macrophages and neutrophils are central; it is not classically autoimmune (no defining autoantibody, no HLA-restricted T-cell autoimmunity).

Tissue damage mechanisms: acute neutrophilic/monocytic inflammation of fascia, serosa, skin, synovium; chronic damage via AA amyloid fibril deposition (oxidative/proteotoxic, see amyloid).

Molecular profiling: Patient PBMCs/monocytes show elevated baseline mtROS, augmented LPS-induced cytokines, ER-stress transcriptional signatures, and altered metabolism (a "metabolic signature" of TNFRSF1A mutation has been reported — see Frontiers/PubMed 36752501).

Cell types (suggested CL terms): monocyte CL:0000576; macrophage CL:0000235; neutrophil CL:0000775; fibroblast CL:0000057 (fasciitis); endothelial cell CL:0000115.

7. Anatomical Structures Affected

Organ/system level: - Skin and subcutaneous tissue / fascia (UBERON: skin UBERON:0002097; fascia UBERON:0007798) — migratory erythematous rash overlying painful muscle. - Skeletal muscle (UBERON:0001134) — myalgia from monocytic fasciitis. - Serous membranes / peritoneum (peritoneum UBERON:0002358; pleura UBERON:0000977) — sterile peritonitis, pleuritis. - Eye / periorbital region (conjunctiva UBERON:0001811; orbital region UBERON:0001697) — conjunctivitis, periorbital edema. - Joints / synovium (synovial joint UBERON:0002217) — arthralgia/arthritis. - Kidney (UBERON:0002113) — the principal target of AA amyloidosis. - Reticuloendothelial system — lymphadenopathy, splenomegaly (spleen UBERON:0002106; lymph node UBERON:0000029). - Systems involved: musculoskeletal, integumentary, gastrointestinal/serosal, ophthalmic, renal/genitourinary, hematologic/immune.

Tissue/cell level: inflammatory infiltration of fascia (monocytic fasciitis), dermis (perivascular mononuclear infiltrate), serosa, and synovium; amyloid deposition in renal glomeruli/interstitium.

Subcellular level (GO cellular component): - Endoplasmic reticulum — GO:0005783 (site of mutant-receptor retention) - Mitochondrion — GO:0005739 (source of pathogenic ROS) - Plasma membrane — GO:0005886 (TNFR1 normal locale) - Autophagosome — GO:0005776

Localization/lateralization: systemic; cutaneous/muscular manifestations are often migratory and may be unilateral at any moment but are not fixed-sided; serositis and amyloidosis are systemic/bilateral.

8. Temporal Development

Onset: typically childhood, median around 4 years, but described from infancy to >50 years (later onset more common with R92Q/P46L). Onset pattern is acute, recurrent.
Disease course: episodic/recurrent-remittent. Discrete attacks of fever + serositis + myalgia/rash recurring at irregular intervals (~every 4–6 weeks), each lasting ~5–25 days (often 1–3 weeks) — notably longer than FMF attacks.
Progression: Generally non-progressive between attacks in those without amyloidosis; some patients have decreasing attack frequency with age, while a subset develop persistent subclinical inflammation that culminates in AA amyloidosis (the principal progressive, organ-threatening sequela).
Remission patterns: Individual attacks are self-limited (spontaneous resolution); treatment-induced remission of attacks and normalization of acute-phase reactants is achievable with IL-1 blockade.
Critical period for intervention: sustained control of inflammation (normalizing SAA/CRP) is the window to prevent amyloidosis; once renal amyloid causes significant proteinuria/CKD, damage is harder to reverse.

9. Inheritance and Population

Epidemiology. - Prevalence: rare; GeneReviews estimates ~1 in 1,000,000 worldwide (likely an underestimate given under-recognition and low-penetrance carriers). TRAPS is the second most common hereditary periodic fever after FMF in many European cohorts. - Incidence: not precisely established (orphan disease).

Genetic transmission: - Inheritance pattern: Autosomal dominant (50% transmission risk per offspring). - Penetrance: High for cysteine-disrupting variants and T50M; markedly reduced for R92Q and P46L. Many R92Q carriers are asymptomatic. - Expressivity: highly variable, even within families carrying the same mutation. - Genetic anticipation: Not a feature (this is not a repeat-expansion disorder). - Germline mosaicism / de novo: de novo mutations occur; mosaicism reported uncommonly. - Founder effects: Original FHF kindred Irish/Scottish; specific variants show population clustering. R92Q and P46L are common population variants rather than founder disease alleles in the classic sense. - Consanguinity: Not relevant (dominant disease). - Carrier "frequency": For low-penetrance alleles, gnomAD shows R92Q ~0.5–1% in some populations and P46L enriched in African-ancestry groups — these are heterozygous susceptibility alleles, not recessive carrier states.

Demographics: Reported across many ethnicities; no strong sex bias (roughly M:F ≈ 1:1, perhaps slight female excess in some series). Geographic distribution of variants varies (P46L more frequent in West African populations). Age distribution skews to childhood onset but spans all ages.

10. Diagnostics

Clinical/laboratory: - Acute-phase reactants during attacks: elevated CRP (HP:0011227), ESR (HP:0003565), serum amyloid A (SAA), neutrophilic leukocytosis, reactive thrombocytosis, anemia of chronic disease; polyclonal hypergammaglobulinemia. Persistently elevated SAA between attacks signals amyloidosis risk. - Soluble TNFR1 (sTNFR1): classically low/inappropriately reduced plasma levels between attacks (McDermott 1999 noted ~half-normal soluble TNFR1) — supportive but not diagnostic; the sTNFR1/sTNFR2 ratio has been explored for differential diagnosis. - LOINC: CRP (e.g., 1988-5), ESR (4537-7), albumin/creatinine ratio for renal amyloid monitoring.

Biomarkers: SAA and CRP for disease activity; proteinuria for amyloid surveillance.

Imaging/biopsy: - Histopathology of muscle/fascia: monocytic fasciitis (panniculitis/fasciitis with mononuclear infiltrate) rather than true myositis — characteristic. - Skin biopsy: superficial/deep perivascular and interstitial mononuclear infiltrate. - Tissue biopsy with Congo red staining (apple-green birefringence) — gold standard to confirm AA amyloidosis (subcutaneous fat, rectal, or renal biopsy); immunohistochemistry confirms SAA-type (AA) amyloid. - SAP scintigraphy (where available) to assess amyloid burden.

Genetic testing (definitive): - Targeted TNFRSF1A sequencing (single-gene) confirms diagnosis when clinical suspicion is high. - Hereditary periodic fever / autoinflammatory NGS gene panels (covering MEFV, MVK, NLRP3, TNFRSF1A, etc.) are standard first-line genetic testing for undifferentiated periodic fever. - WES/WGS reserved for atypical/unsolved cases. - CMA, karyotyping, FISH, mtDNA, and repeat-expansion testing are not applicable (coding missense disease). - Interpretation caveat: finding R92Q or P46L requires cautious interpretation given reduced penetrance — genotype must be integrated with phenotype.

Clinical criteria / classification: The Eurofever/PRINTO classification criteria and the newer 2024 EULAR/ACR (AIDA-informed) provisional classification criteria for autoinflammatory periodic fevers are used; historically the "TRAPS clinical score." Key discriminators: attack duration >1 week, migratory myalgia with rash, periorbital edema, positive family history, dominant inheritance.

Differential diagnosis: FMF (shorter attacks, AR, MEFV, colchicine-responsive), hyper-IgD/mevalonate kinase deficiency (MKD/HIDS) (MVK, early onset, cervical adenitis, elevated IgD), cryopyrin-associated periodic syndromes (CAPS/NLRP3), PFAPA, systemic JIA / adult-onset Still disease, Behçet disease, and infection/malignancy.

Screening: No population newborn screening. Cascade genetic testing of at-risk relatives in known-mutation families is appropriate; prenatal/preimplantation testing is possible for high-penetrance variants but ethically nuanced given variable expressivity.

11. Outcome / Prognosis

Survival/life expectancy: Generally normal life expectancy if amyloidosis is prevented/controlled. Untreated, AA amyloidosis is the major determinant of mortality, via progressive renal failure.
Disease-specific mortality: Driven almost entirely by amyloid-related end-organ (renal, and less often hepatic/cardiac/GI) failure.
Morbidity: Recurrent prolonged painful attacks → chronic pain, fatigue, missed school/work; ocular involvement; complications of chronic steroid use historically.
AA amyloidosis frequency: Historically reported in ~10–25% of patients overall, higher (up to ~25%+) for cysteine/T50M genotypes and very low for R92Q/P46L. Per GeneReviews, once amyloidosis develops, "proteinuria and kidney failure occur in 80%–90%" of those affected.
Prognostic factors: Genotype is the strongest predictor — cysteine-disrupting variants and T50M predict severe, persistent disease and amyloid risk; R92Q/P46L predict mild/self-limited disease. Persistently elevated SAA/CRP between attacks predicts amyloidosis. Early effective IL-1 blockade improves outcomes.
Recovery potential: Attacks fully resolve between episodes; with modern biologics, clinical and biochemical remission is achievable in the majority, and continuous therapy can prevent or stabilize amyloidosis.

12. Treatment

Goals: abort/prevent attacks, normalize acute-phase reactants (CRP/SAA), and prevent AA amyloidosis.

Pharmacotherapy / biologics (mainstay): - IL-1 inhibitors — first-line for persistent disease: - Anakinra (recombinant IL-1 receptor antagonist) — rapid, effective; useful diagnostically and for amyloidosis-complicated disease. - Canakinumab (anti-IL-1β monoclonal antibody) — the only biologic with a pivotal RCT and regulatory approval for TRAPS (FDA/EMA approval for periodic fever syndromes including TRAPS). In the phase 3 CLUSTER trial (De Benedetti et al., NEJM 2018, PMID:29768139; ClinicalTrials.gov NCT02059291), canakinumab controlled and prevented flares in TRAPS, MKD/HIDS, and colchicine-resistant FMF.

> *"Canakinumab was effective... in controlling and preventing flares in patients with colchicine-resistant familial Mediterranean fever, mevalonate kinase deficiency... and TRAPS."* — De Benedetti et al., *NEJM* 2018 (**PMID:29768139**)

Modality: monoclonal antibody (canakinumab) / recombinant protein (anakinra). Suggested annotation: treatment_term NCIT:C15986 (Pharmacotherapy) + therapeutic_agent (canakinumab/anakinra), therapeutic_modality: MONOCLONAL_ANTIBODY (canakinumab).
TNF inhibitor — etanercept (soluble TNFR2-Fc fusion): historically used; partially effective but with waning/incomplete responses and poor long-term adherence:

"Etanercept reduces symptoms and serum levels of inflammatory markers of TRAPS in a dose-dependent manner, but does not completely normalize symptoms or acute-phase reactant levels." — Bulua et al., Arthritis Rheum 2012 (PMID:22006113)

Important pharmacologic caveat: monoclonal anti-TNF antibodies (infliximab, and adalimumab) can paradoxically worsen TRAPS (reported flare induction) and are generally avoided; etanercept (receptor decoy) behaves differently from anti-TNF mAbs here.
IL-6 blockade (tocilizumab): reported effective in refractory/biologic-experienced cases (off-label).
Corticosteroids: abort/attenuate acute attacks (high-dose during flares) but chronic steroid use causes toxicity and is not a long-term solution; escalating dose requirements are common.
NSAIDs: symptomatic relief only.
Colchicine: largely ineffective in TRAPS (unlike FMF) — an important contrast.

Pharmacogenomics: Response is genotype-correlated at the disease-allele level (severe genotypes need continuous biologics) rather than via drug-metabolism PGx; no validated CPIC-style PGx guidance specific to TRAPS.

Advanced/experimental therapeutics: No approved gene/cell/RNA therapy. Emerging interest in agents targeting ER stress, mtROS, NLRP3 inflammasome, and JAK inhibitors in refractory autoinflammation — investigational only.

Supportive/management of amyloidosis: suppress inflammation to halt amyloid; manage CKD/nephrotic syndrome (ACE inhibitors/ARBs, dialysis); renal transplantation in end-stage renal disease, with continued IL-1 blockade to protect the graft.

Suggested MAXO terms: Pharmacotherapy (NCIT:C15986); supportive care (MAXO:0000950); organ transplantation/renal transplant (MAXO:0010039); genetic counseling (MAXO:0000079); dietary/supportive management as applicable. (Use NCIT/CHEBI therapeutic_agent for canakinumab, anakinra, etanercept, prednisone; note canakinumab/anakinra/etanercept are biologics — likely need NCIT rather than CHEBI agents; corticosteroid CHEBI:50858/prednisone CHEBI:8382; colchicine CHEBI:23359 noted as ineffective.)

13. Prevention

Primary prevention: Not preventable (genetic). Genetic counseling for affected families is the key primary-prevention tool; prenatal/preimplantation genetic testing is feasible for high-penetrance variants.
Secondary prevention (early detection): Cascade genetic testing of at-risk relatives; early diagnosis enables early anti-inflammatory therapy.
Tertiary prevention (complication prevention): the central, achievable goal — continuous suppression of inflammation (normalizing SAA/CRP with IL-1 blockade) to prevent AA amyloidosis, plus monitoring urinalysis/proteinuria and renal function for early amyloid detection.
Immunization: No vaccine (not infectious). Standard immunizations advised, with awareness that vaccination can occasionally trigger a flare and that live vaccines need consideration on biologics.
Counseling: genetic counseling regarding autosomal-dominant 50% transmission, variable expressivity, and the special interpretive challenges of R92Q/P46L (MAXO:0000079).
Public/environmental health: Not applicable.

14. Other Species / Natural Disease

Taxonomy: Human disease — Homo sapiens (NCBITaxon:9606).
Orthologous gene: mouse Tnfrsf1a (NCBI Gene 21937); the gene/receptor (TNFR1/p55) is highly conserved across mammals.
Natural disease in other species: No well-recognized spontaneous TRAPS-equivalent in companion animals or wildlife (OMIA has no established orthologous natural disease). TRAPS is essentially a human germline disorder; animal "disease" is engineered (see §15).
Comparative biology / conservation: TNF–TNFR1 signaling and the cysteine-rich-domain architecture are deeply evolutionarily conserved, which is why mouse knock-ins recapitulate aspects of the disease.
Zoonotic potential / transmission: None (non-infectious genetic disease).

15. Model Organisms

Mouse "knock-in" models: The key model is the TNFR1 knock-in mouse carrying TRAPS-associated mutations (e.g., T50M; C33Y), generated and characterized in the same body of work establishing the misfolding/ER-retention and mtROS mechanisms (Lobito et al. Blood 2006, PMID:16684962; Bulua et al. J Exp Med 2011, PMID:21282379). These mice show ER retention of mutant TNFR1, elevated mitochondrial ROS, and enhanced inflammatory responses to LPS, recapitulating the cellular phenotype.

"...a mouse 'knock-in' model of TRAPS... TRAPS mutant TNFR1 molecules were retained intracellularly and colocalized with endoplasmic reticulum markers." — Lobito et al. 2006 (PMID:16684962)

Cellular / in vitro models: transfected cell lines expressing mutant TNFR1; patient-derived monocytes/PBMCs and mouse embryonic fibroblasts (MEFs) harboring TRAPS mutations — used to demonstrate elevated baseline mtROS and augmented cytokine output (Bulua 2011, PMID:21282379). iPSC-derived myeloid models are an emerging avenue.
Model types available: knock-in (point-mutation) mice; transgenic/overexpression cell systems; primary patient cells (ex vivo).
Phenotype recapitulation: Models faithfully reproduce the molecular phenotype (ER retention, mtROS, hyper-responsive innate cytokine secretion, NF-κB/MAPK activation). They are somewhat less faithful to the full clinical periodic-fever syndrome (the dramatic recurrent multi-organ human attacks and AA amyloidosis are incompletely modeled) — a candidate HUMAN_MODEL_MISMATCH consideration for dismech: molecular mechanism well-modeled, but periodicity/amyloidosis less so.
Applications: dissecting the misfolding→ER-stress→mtROS→cytokine axis, testing antioxidants/IL-1 blockade, and validating that IL-1β is the key effector.
Resources: MGI (mouse Tnfrsf1a), IMPC/KOMP for null alleles (note: null alleles model TNF-loss, not the TRAPS gain-type mechanism — use knock-in lines for disease modeling).

Summary of Key Verified Citations (re-validate before YAML commit)

Claim	Citation	PMID	Status
Gene discovery, disulfide-disrupting missense, low soluble TNFR1	McDermott et al., Cell 1999;97:133–144	10199409	✅ verified
Mutational spectrum, ancestral origins, genotype–phenotype	Aksentijevich et al., Am J Hum Genet 2001;69:301–314	11443543	⚠️ verify exact digits
Misfolding / ER retention / abnormal oligomers (+ knock-in mouse)	Lobito et al., Blood 2006;108:1320–1327	16684962	✅ verified
Mitochondrial ROS drives cytokines, elevated in TRAPS	Bulua et al., J Exp Med 2011;208:519–533	21282379	✅ verified
Concerted WT+mutant receptor action	Simon et al., PNAS 2010	~20133695	⚠️ verify before use
Etanercept partially effective	Bulua et al., Arthritis Rheum 2012;64:908–913	22006113	✅ verified
Phenotype of 158 cases; R92Q ~34%, T50M ~10%	Lachmann et al., Ann Rheum Dis 2014;73:2160–2167	23965844	✅ verified
Canakinumab RCT (CLUSTER) approval evidence	De Benedetti et al., NEJM 2018 (NCT02059291)	29768139	✅ verified

Sources consulted: - McDermott et al., Cell 1999 — PubMed - Aksentijevich et al., Am J Hum Genet 2001 — PMC1235304 - Lobito et al., Blood 2006 — PMC1895878 - Bulua et al., J Exp Med 2011 — PMC3058571 - Bulua et al., Arthritis Rheum 2012 — PubMed - Lachmann et al., Eurofever/EUROTRAPS 2014 — PMC4251160 - De Benedetti et al., CLUSTER trial, NEJM 2018 — PubMed and NCT02059291 - GeneReviews: TNF Receptor-Associated Periodic Fever Syndrome — NBK586171 - Revisiting TRAPS: Current Perspectives, Int J Mol Sci 2020 — MDPI - R92Q age-at-onset cohort, Front Immunol 2017 — PMC5366323 - NORD: TRAPS

Curation flags for dismech: (1) Re-fetch every PMID with just fetch-reference and confirm each snippet is an exact substring before committing — the two ⚠️ PMIDs (Aksentijevich 11443543, Simon ~20133695) need digit re-verification. (2) The R92Q/P46L low-penetrance variants are an ideal place to record a mechanistic_hypotheses/reduced-penetrance nuance. (3) Consider a HUMAN_MODEL_MISMATCH discussion note for the mouse knock-in (molecular mechanism modeled; full periodic-fever/amyloidosis phenotype not). (4) evidence_source tags: McDermott/Aksentijevich/Lachmann/De Benedetti/Bulua-2012 = HUMAN_CLINICAL; Lobito (knock-in mouse + transfected cells) = mix of MODEL_ORGANISM + IN_VITRO (split into separate evidence items); Bulua-2011 mtROS = mix of MODEL_ORGANISM (MEFs/mice) + IN_VITRO (human cells) — split accordingly.

TNF Receptor-Associated Periodic Syndrome

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Summary of Key Verified Citations (re-validate before YAML commit)