Prevalence of CYP2C8 polymorphisms in a North Indian population

CYP2C8 is an important member of the cytochrome P450 family of enzymes; it affects the activity of various drugs used in routine clinical practice, including amiodarone, chloroquine, amodiaquine, and repaglinide, as well as endogenous compounds, such as arachidonic acid and retonic acid. It is also the main enzyme involved in the metabolism of the widely used anticancer drug Paclitaxel, which has a very narrow therapeutic index. There is evidence that single nucleotide polymorphisms in the CYP2C8 gene influence the adverse reactions and/or the efficacy of drugs metabolized by this enzyme. We examined the allele and genotype frequencies of widely studied functional polymorphisms of the CYP2C8 gene in a North Indian population. We assayed the genomic DNA of at least 251 healthy unrelated North Indians for CYP2C8*2, CYP2C8*3 (G416A, A1196G), and CYP2C8*4 genetic polymorphisms by RFLP technique. These results were compared to information on other populations. The allelic frequencies of CYP2C8*2, CYP2C8*3, and CYP2C8*4 were found to be 3, 4, and 4% respectively. The two CYP2C8*3 polymorphisms (G416A and A1196G) were found to be completely linked to each other. Allele frequencies of CYP2C8 genetic variants in northern Indians were found to have a distinct pattern that differs from that of southern Indian and other global populations. This is the first report from North India on CYP2C8 polymorphisms. Ethnic differences with respect to polymorphisms are the molecular basis of interethnic variability in pharmacokinetics. Our study may help in rational use of drugs that are substrates for CYP2C8 in this population.