Carbamazepine – HLA Pharmacogenomics — SCE Neurology MCQ

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HardEpilepsy & Seizure DisordersCarbamazepine – HLA PharmacogenomicsSCE Neurology

A 45-year-old man with epilepsy on carbamazepine develops a rash 2 weeks after starting the medication. He is of Han Chinese ethnicity. What pharmacogenomic marker should have been checked before prescribing carbamazepine?

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Correct answer: A — HLA-A*31:01 and HLA-B*15:02

HLA-B*15:02 is strongly associated with carbamazepine-induced Stevens-Johnson syndrome and toxic epidermal necrolysis in patients of Han Chinese, Thai, and other Southeast Asian ancestry. HLA-A*31:01 is associated with carbamazepine-induced DRESS syndrome across multiple ethnicities. NICE NG217 and BNF recommend testing for HLA-B*15:02 in patients of Southeast Asian origin and HLA-A*31:01 in appropriate populations before starting carbamazepine. A: HLA-B*57:01 is for abacavir hypersensitivity (HIV). C: CYP2D6 is for codeine/tamoxifen metabolism. D: TPMT is for azathioprine. E: G6PD is for haemolysis risk with certain drugs.

Reference: NICE NG217 (2025); CPIC Carbamazepine Pharmacogenomics Guidelines; BNF