Cytochrome P450 2C9 (CYP2C9), a member of the CYP2C enzyme subfamily, ranks amongst the most important drug metabolizing enzymes in humans.
Human CYP2C9 has been shown to exhibit genetic polymorphism. In addition to the wild-type protein CYP2C9*1, at least 30 single nucleotide polymorphisms (SNPs) have been reported within the coding region of the CYP2C9 gene producing the variant allozymes. CYP2C9*13 is one of them. It involves a T-to-C transversion at nucleotide position 269 causing a mutation at codon 90, which results in a Leu->Pro substitution. Frequency analysis indicated approximately 2% of the Chinese population carry the allele.
CYP2C9*13 was found in Japanese and Korean, too. CYP2C9*13 allele frequencies in East Asian populations is summarized in Table S of this paper.
CYP2C9*13 allele was correlated with reduced plasma clearance of drugs that are substrates for CYP2C9.