title: Low frequency of CYP2A6 gene polymorphism as revealed by a one-step polymerase chain reaction method.
abstract: Human cytochrome P450 2A6 (CYP2A6) has been shown to metabolically activate carcinogens and mutagens. Genetic polymorphisms for CYP2A6 have been reported previously in different ethnic groups using a two-step polymerase chain reaction (PCR) method to identify CYP2A6*1, CYP2A6*2 and CYP2A6*3. Moreover, a new truncated allele has been recently identified in a Japanese population. We report here a one-step PCR amplification of the CYP2A6 gene from human genomic DNA and the detection of intact CYP2A6 alleles by restriction enzyme digestion. The diagnostic exon (exon 3) of the CYP2A6 gene was amplified from human genomic DNA with a primer pair. The forward primer is unique to the CYP2A6 gene, which eliminates previous problems in amplifying two highly homologous CYP2A genes, CYP2A7 and CYP2A13, in humans. The resulting PCR products (214 bp) were digested with XcmI or DdeI to detect the presence of CYP2A6*2 or CYP2A6*3 alleles, respectively. The allelic frequencies for CYP2A6*2 were 2.3% (n = 320) in the Caucasian and 0.7% (n = 71) in the Chinese populations, respectively. CYP2A6*3 allelic frequency in the Chinese population was 0.7%; while no CYP2A6*3 allele was detected in the Caucasian population. The allelic frequencies are relatively low and the reason for this discrepancy between different methods is discussed.
authors.affiliation: Division of Molecular Epidemiology, National Center for Toxicological Research, Jefferson, Arkansas 72079, USA.
authors.forename: G F
authors.initials: GF
authors.lastname: Chen
authors.forename: Y M
authors.initials: YM
authors.lastname: Tang
authors.forename: B
authors.initials: B
authors.lastname: Green
authors.forename: D X
authors.initials: DX
authors.lastname: Lin
authors.forename: F P
authors.initials: FP
authors.lastname: Guengerich
authors.forename: A K
authors.initials: AK
authors.lastname: Daly
authors.forename: N E
authors.initials: NE
authors.lastname: Caporaso
authors.forename: F F
authors.initials: FF
authors.lastname: Kadlubar
mesh_terms: D001189:Aryl Hydrocarbon Hydroxylases; D001483:Base Sequence; D065637:Cytochrome P-450 CYP2A6; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics*; D017931:DNA Primers; D005787:Gene Frequency; D005838:Genotype; D006801:Humans; D007438:Introns; D006899:Mixed Function Oxygenases / Q000235:genetics*; D016133:Polymerase Chain Reaction / Q000379:methods; D011110:Polymorphism, Genetic
chemical_list: D017931:DNA Primers; D003577:Cytochrome P-450 Enzyme System; D006899:Mixed Function Oxygenases; D001189:Aryl Hydrocarbon Hydroxylases; C585710:CYP2A6 protein, human; D065637:Cytochrome P-450 CYP2A6