Autoinflammatory Syndromes

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Autoinflammatory Syndromes: Core Concepts - Fiery Fevers & Flares

  • Primarily disorders of innate immunity (vs. adaptive in autoimmune).
  • Pathogenesis: Dysregulated inflammasomes or cytokine pathways, leading to uncontrolled inflammation.
  • Key pro-inflammatory cytokines mediating flares:
    • Interleukin-1β (IL-1β)
    • Tumor Necrosis Factor-alpha (TNF-α)
    • Interleukin-6 (IL-6)
  • Clinical hallmarks: Recurrent, unprovoked episodes of:
    • High fever ("fiery fevers")
    • Serositis (e.g., pleuritis, pericarditis, peritonitis)
    • Various skin rashes (e.g., urticarial)
    • Arthralgia or arthritis
  • Often have a strong genetic predisposition.

⭐ Autoinflammatory diseases are primarily driven by dysregulation of the innate immune system, unlike autoimmune diseases which involve the adaptive immune system (T and B cells).

Familial Mediterranean Fever (FMF) - Periodic Perils

  • Genetic: Autosomal recessive, MEFV gene mutation (pyrin).
  • Pathophysiology: Pyrin inflammasome dysregulation → ↑IL-1β.
  • Features: Recurrent episodes (12-72 hrs) of:
    • Fever (abrupt, high-grade).
    • Serositis (peritonitis, pleuritis) → severe pain.
    • Arthritis (mono/oligo, lower limbs).
    • Erysipelas-like erythema (lower leg/foot).
  • Labs: ↑ESR, CRP during attacks.
  • Diagnosis: Tel Hashomer criteria; MEFV gene testing.
  • Treatment:
    • Prophylaxis: Colchicine (0.6-1.2 mg/day, up to 2.4 mg/day) lifelong.
    • Acute attacks: NSAIDs.
  • Complication: AA amyloidosis (renal failure).
  • 📌 Mnemonic: FMF SCRIPT (Serositis, Colchicine/Complication-Amyloidosis, Recurrent fever, Inflammation markers, Pain-abdominal/chest, MEFV gene, Tel Hashomer criteria).

Colchicine is the mainstay of FMF treatment, effectively preventing attacks and the dreaded complication of AA amyloidosis.

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Other Key Monogenic Syndromes - Alphabet Soup Inflamed

SyndromeGene (Protein)Key FeaturesTreatment Hint
TRAPS (TNF Receptor-Associated Periodic Syndrome)TNFRSF1A (TNF Receptor 1)Prolonged fevers (>7 days), migratory rash, periorbital edema, abdominal/chest pain. 📌 TRAPS catch FEver PERIodically.Corticosteroids, Etanercept
HIDS/MKD (Hyper-IgD Syndrome / Mevalonate Kinase Deficiency)MVK (Mevalonate Kinase)Recurrent fevers (early onset <1 yr), ↑IgD (HIDS), cervical lymphadenopathy, GI upset. 📌 HIgD for HIDS.NSAIDs, Steroids, IL-1 inhibitors
CAPS (Cryopyrin-Associated Periodic Syndromes)NLRP3 (Cryopyrin)Urticarial rash (cold-induced or persistent), fevers, sensorineural deafness, arthralgia. 📌 CAPS on EARS & SKIN.IL-1 inhibitors (Anakinra)

Diagnostic & Management Principles - Cooling the Flames

  • Clinical Suspicion: Recurrent, unexplained fevers & systemic inflammation (e.g., serositis, rash, arthritis).
  • Investigations:
    • Inflammatory markers: ↑ CRP, ↑ ESR, ↑ SAA.
    • Genetic testing: Confirms specific syndromes (e.g., FMF, TRAPS); aids targeted therapy. Limitations: VUS, not all causative genes identified.
  • Management Goals: Control inflammation, prevent organ damage (esp. amyloidosis), improve QoL.
    • Acute Flares: NSAIDs, corticosteroids.
    • Chronic/Prophylactic:
      • Colchicine (esp. FMF).
      • Biologics: IL-1 inhibitors (anakinra, canakinumab), IL-6 inhibitors (tocilizumab), TNF inhibitors.

⭐ Monitoring Serum Amyloid A (SAA) levels is crucial in chronic autoinflammatory diseases to assess disease activity and the risk of developing secondary AA amyloidosis.

High‑Yield Points - ⚡ Biggest Takeaways

  • Autoinflammatory syndromes: Innate immunity dysregulation, not adaptive like autoimmune diseases.
  • Key features: Recurrent fevers, systemic inflammation, often genetic.
  • FMF: MEFV gene, colchicine prevents attacks and AA amyloidosis.
  • CAPS: NLRP3 gene, IL-1 inhibitors (e.g., anakinra) are mainstay treatment.
  • TRAPS: TNFRSF1A gene, prolonged fevers; corticosteroids or IL-1/TNF inhibitors may be used.
  • HIDS/MKD: MVK gene, presents with high IgD (variable) and fevers.
  • AA amyloidosis is a critical long-term complication across several syndromes if untreated.

Practice Questions: Autoinflammatory Syndromes

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Flashcards: Autoinflammatory Syndromes

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The characteristics of SLE may be remembered with the mnemonic "RASH OR PAIN":R: _____A: Arthritis (usually involving > 2 joints)S: Serositis (pleuritis and pericarditis)H: Hematologic disorders (e.g. cytopenias)O: Oral or nasopharyngeal ulcers (usually painless)R: Renal diseaseP: PhotosensitivityA: Antinuclear antibodiesI: Immunologic disorder (anti-dsDNA, anti-Sm, antiphospholipid) N: Neurologic disorder (seizures, psychosis)

TAP TO REVEAL ANSWER

The characteristics of SLE may be remembered with the mnemonic "RASH OR PAIN":R: _____A: Arthritis (usually involving > 2 joints)S: Serositis (pleuritis and pericarditis)H: Hematologic disorders (e.g. cytopenias)O: Oral or nasopharyngeal ulcers (usually painless)R: Renal diseaseP: PhotosensitivityA: Antinuclear antibodiesI: Immunologic disorder (anti-dsDNA, anti-Sm, antiphospholipid) N: Neurologic disorder (seizures, psychosis)

Rash (malar or discoid)

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