Ethnic variation in CYP2A6*7, CYP2A6*8 and CYP2A6*10 as assessed with a novel haplotyping method

Cytochrome P450 2A6 is the main human nicotine metabolizing enzyme coded for by a highly polymorphic gene, CYP2A6. CYP2A6*7, CYP2A6*8 and CYP2A6*10 are variant alleles common to Asian ethnicities. The CYP2A6*7 and CYP2A6*8 alleles each contain a non-synonymous single nucleotide polymorphism (SNP) 6558T > C and 6600G > T, respectively, whereas the CYP2A6*10 haplotype allele contains both. We have developed the first haplo-typing assay; it can unambiguously distinguish the CYP2A6*7 CYP2A6*8 and CYP2A6*10 alleles. The allele frequencies of these three variants were assessed using the novel haplotyping assay in Chinese-Canadian (n = 112), Chinese-American (n = 221), Taiwanese (n = 319), Korean-American (n = 207) and Japanese-Canadian (n = 64) populations, as well as in Caucasian (n = 110) and African-Canadian (n = 113) populations. Our new method demonstrated higher frequencies of CYP2A6*7 and CYP2A6* 10, and a lower frequency of CYP2A6*8 in Asian populations, but no significant change of allele frequencies in Caucasian or African-Canadian populations. Pharmacogenetics and Genomics 15:189-192 (c) 2005 Lippincott Williams & Wilkins.