CYP2C19

Overview
Cytochrome P450 2C19 (abbreviated CYP2C19), a member of the cytochrome P450 mixed-function oxidase system, is involved in the metabolism of xenobiotics in the body. It is involved in the metabolism of several important groups of drugs including clopidogrel many proton pump inhibitors and antiepileptics. In humans, the CYP2C19 protein is encoded by the CYP2C19 gene.

CYP2C19 has been annotated as (R)-limonene 6-monooxygenase and (S)-limonene 6-monooxygenase in UniProt.

The inability to metabolize clopidogrel, or clopidogrel resistance, has been attributed, at least in part (about 11%), to genetic variations in Cytochrome P450 2C19.

Function
This gene encodes a member of the cytochrome P450 superfamily of enzymes. The cytochrome P450 proteins are monooxygenases that catalyze many reactions involved in drug metabolism and synthesis of cholesterol, steroids and other lipids. This protein localizes to the endoplasmic reticulum and is known to metabolize many xenobiotics, including the anticonvulsive drug mephenytoin, omeprazole, diazepam and some barbiturates. Polymorphism within this gene is associated with variable ability to metabolize mephenytoin, known as the poor metabolizer and extensive metabolizer phenotypes. The gene is located within a cluster of cytochrome P450 genes on chromosome no.10 arm q24.

Genetic polymorphism and pharmacogenomics
Genetic polymorphism (mainly CYP2C19*2, CYP2C19*3 and CYP2C19*17) exists for CYP2C19 expression, with approximately 3–5% of Caucasian and 15–20% of Asian populations being poor metabolisers with no CYP2C19 function.