CYP2C19

About CYP2C19

CYP2C19 on chromosome 10q23.33 encodes a liver cytochrome P450 enzyme involved in metabolizing several widely used medicines, including the antiplatelet drug clopidogrel, proton pump inhibitors, some antidepressants, and the antifungal voriconazole. Clopidogrel is a prodrug that requires CYP2C19 to become active, so people carrying loss of function alleles such as CYP2C19 star 2 form less active drug, and regulators have added warnings to its labeling about reduced effectiveness in poor metabolizers. Loss of function alleles are considerably more common in East Asian and Pacific Islander populations than in European populations. The star 17 allele increases enzyme expression and is associated with ultrarapid metabolism. CYP2C19 is one of the genes most frequently included in clinical pharmacogenomic testing panels, and interpretation guidance is published by expert consortia.