High-intensity interval training — MRCP Part 1 MCQ

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HardExercise PhysiologyHigh-intensity interval trainingMRCP Part 1

A 16-year-old boy has recurrent haemophagocytic lymphohistiocytosis, massive splenomegaly and severe Crohn-like colitis. His maternal uncle had similar episodes, but neither has lymphoma. Which protein deficiency is most likely?

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Correct answer: A — XIAP

The best answer is “XIAP”. XIAP deficiency causes XLP2 and is particularly associated with recurrent HLH, splenomegaly and inflammatory bowel disease. Unlike SH2D1A/SAP-related XLP1, lymphoma is not a characteristic feature and episodes need not be triggered by Epstein-Barr virus. Perforin, Munc13-4 and syntaxin-11 defects cause familial HLH through cytotoxic granule pathways, but the X-linked pedigree and Crohn-like enterocolitis point specifically to XIAP deficiency.

Reference: X-Linked Lymphoproliferative Disease — GeneReviews: https://www.ncbi.nlm.nih.gov/books/NBK1406/