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HLA-B*1502 pharmacogenomics — GPhC CRA MCQ

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HardAdverse Drug ReactionsHLA-B*1502 pharmacogenomicsGPhC CRA

A 30-year-old woman presents with a prescription for carbamazepine 100 mg twice daily for newly diagnosed epilepsy. She is of Han Chinese heritage. The prescriber has noted that HLA-B*1502 testing should be performed before starting treatment. What is the rationale for this test?

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Correct answer: E — HLA-B*1502 positive individuals are at increased risk of Stevens-Johnson syndrome and toxic epidermal necrolysis with carbamazepine

The HLA-B*1502 allele, which is more prevalent in individuals of Han Chinese, Thai, and other South-East Asian heritage, is associated with a significantly increased risk of carbamazepine-induced Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN). The BNF recommends HLA-B*1502 testing before starting carbamazepine in at-risk populations. If the test is positive, carbamazepine should be avoided.

Reference: BNF; MHRA Drug Safety Update