Before starting allopurinol in a Han Chinese patient with newly diagnosed gout, many clinicians test for a genetic marker that predicts severe cutaneous adverse reactions such as Stevens-Johnson syndrome and toxic epidermal necrolysis. This marker is:
- A HLA-B*5801 ✓
- B HLA-B*5701
- C HLA-B*1502
- D TPMT deficiency genotype
Correct answer: A. HLA-B*5801
Explanation
HLA-B*5801 carriage strongly predicts allopurinol-induced severe cutaneous adverse reactions, and the association is especially strong in Han Chinese, Thai and Korean populations, so testing is recommended before starting the drug in these groups. HLA-B*1502 predicts carbamazepine-induced SJS, HLA-B*5701 predicts abacavir hypersensitivity, and TPMT deficiency relates to thiopurine myelosuppression, making all three distractors plausible but incorrect.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.