A patient on carbamazepine for trigeminal neuralgia develops a severe maculopapular rash. Pharmacogenomic testing reveals HLA-B*15:02 positivity. This allele predicts risk for which adverse reaction?

• A Agranulocytosis and aplastic anemia
• B Stevens-Johnson syndrome and toxic epidermal necrolysis ✓
• C Drug reaction with eosinophilia and systemic symptoms (DRESS)
• D Carbamazepine-induced hyponatremia via SIADH

Explanation

HLA-B*15:02, found predominantly in Han Chinese and Southeast Asian populations, is strongly associated with carbamazepine-induced Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN). Pre-prescription genetic screening for HLA-B*15:02 is now recommended by the FDA and incorporated into Asian treatment guidelines before initiating carbamazepine. HLA-A*31:01 is associated with DRESS (option C) across various ethnic groups. Agranulocytosis and hyponatremia are also carbamazepine adverse effects but are not HLA-linked.

Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.