Arg257Cys polymorphism of CYP2A13 in a Chinese population

Human cytochrome P450 2A13 (CYP2A13) is involved in the activation of numerous toxicants and carcinogens, especially in the metabolic activation of 4-(methyl-nitrosamino)-1-(3-pyridyl)-1-butanone (NNK), a major tobacco-specific carcinogen. A functionally significant coding single nucleotide polymorphism (C3375T) in exon 5 of CYP2A13, which results in an amino acid substitution of Arg 257 to Cys, has been recently reported to exist in White, Black, Hispanic, and Asian individuals, with the variant 3375T allele frequencies being 1.9%, 14.4%, 5.8% and 7.7%, respectively. Since genetic background differs between ethnic groups, our present study aims to characterize the CYP2A13 Arg257Cys polymorphism in Chinese.

258 healthy Chinese Han volunteers were involved in this study. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assay was employed to genotype for the Arg257Cys polymorphism.

Of all the 258 subjects, 27 (10.5%) heterozygotes and 1 (0.4%) homozygote for the 257Cys allele were detected. The frequency of the variant 257Cys allele in this Chinese population was 5.6% (95%CI: 4.2-7.0%).

The CYP2A13 Arg257Cys variant represents a common polymorphism in Chinese, with the 257Cys allele frequency being similar to the Hispanic and Asian groups, but significantly lower than the Black.