Before starting allopurinol for chronic tophaceous gout in a 55-year-old man of Thai origin, which screening test is recommended because his ancestry carries a high allele frequency for severe cutaneous adverse reaction risk?
- A HLA-B*58:01 typing ✓
- B HLA-B*57:01 typing
- C HLA-B*15:02 typing
- D TPMT enzyme activity
Correct answer: A. HLA-B*58:01 typing
Explanation
HLA-B*58:01 is strongly associated with allopurinol-induced Stevens-Johnson syndrome and toxic epidermal necrolysis, and the allele frequency is high in Han Chinese, Thai and Korean populations, justifying pre-treatment screening there. HLA-B*15:02 predicts carbamazepine-induced SJS, HLA-B*57:01 predicts abacavir hypersensitivity, and TPMT deficiency predicts azathioprine myelotoxicity. Febuxostat is the usual alternative if the allele is present, though it carries its own cardiovascular caution.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.