skip to main content

X-linked agammaglobulinaemia — RACP Paediatrics MCQ

Instant feedback + full explanation. One question, done properly.

ModerateIDX-linked agammaglobulinaemiaRACP Paediatrics

A 2-year-old boy has had recurrent severe bacterial infections (pneumonia, septic arthritis, meningitis) since 6 months of age. Examination shows absent tonsils and no palpable lymph nodes. Immunoglobulins show absent IgG, IgA, and IgM. B-cell count is zero. What is the most likely diagnosis?

Educational content. Not a substitute for clinical judgement or local policy.

Reveal the answer and explanation

Correct answer: B — X-linked agammaglobulinaemia

A male infant with onset of recurrent severe bacterial infections after 6 months (when maternal antibodies wane), absent tonsils and lymph nodes, agammaglobulinaemia, and absent B cells is classic X-linked agammaglobulinaemia (Bruton disease, BTK gene mutation). Treatment is lifelong immunoglobulin replacement therapy.

Reference: RCH Melbourne – 2023 – Immunodeficiency CPG; RACP Paediatric Curriculum – Immunology