• Definition: genetic condition characterized by impaired function of T cells and thrombocytopenia
• Epidemiology: occurs primarily in males
• Etiology: mutated WAS gene (X-linked recessive inheritance) → impaired signaling to actin cytoskeleton reorganization → defective antigen presentation
• Clinical features
  • Onset of symptoms: from birth
  • Classic triad
    • Purpura (bleeding diathesis)
    • Eczema (high risk of atopic disorders)
    • Recurrent opportunistic infections with encapsulated organisms in the first years of life (e.g., otitis media)
  • Increased risk of autoimmune diseases and hematological malignancies (e.g., lymphoma, leukemia)

Mnemonic

Purpura and eczema are like you’re bit by a WASp.

• Diagnosis
  • Normal or ↓ IgG and IgM
  • ↑ IgE and IgA
  • Thrombocytopenia with small platelets