Before initiating abacavir in an HIV-positive patient, mandatory pharmacogenetic screening is performed to prevent a life-threatening hypersensitivity reaction. Which allele must be tested?
- A HLA-B*2705
- B HLA-B*5701 ✓
- C CYP2D6*4
- D HLA-A*3101
Correct answer: B. HLA-B*5701
Explanation
Abacavir hypersensitivity is a Type IV immune-mediated reaction strongly associated with HLA-A*5701. Positive patients must never receive abacavir. Screening reduced the incidence of immunologically confirmed hypersensitivity from around 8% to near zero. HLA-A*2705 is associated with ankylosing spondylitis. CYP2D6*4 affects drug metabolism. HLA-B*3101 is linked to carbamazepine hypersensitivity in Caucasians.
Reference: Katzung's Basic and Clinical Pharmacology, 15th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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