HLA-B*5801 Testing — RACP Adult Medicine MCQ

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

EasyClinical PharmacologyHLA-B*5801 TestingRACP Adult Medicine

A 50-year-old man is commenced on allopurinol for gout. He is of Southeast Asian descent. What genetic test should be performed before starting allopurinol?

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

Reveal the answer and explanation

Correct answer: D — HLA-B*5801

HLA-B*5801 testing is strongly recommended before commencing allopurinol in patients of Southeast Asian descent (Han Chinese, Thai, Korean – prevalence 6–8%), African American descent (~4%), and Aboriginal Australian populations. HLA-B*5801 positivity confers a markedly increased risk of severe allopurinol hypersensitivity syndrome (AHS – DRESS/SJS/TEN), which carries a mortality of 20–25%. If positive, allopurinol is contraindicated and febuxostat is the alternative xanthine oxidase inhibitor.

Reference: eTG – 2025 – Rheumatology; ACR – 2020 – Gout Guideline; CPIC – 2023 – HLA-B*5801