An improved assay shows no association between the CYP2A6 gene and cigarette smoking behavior

Pianezza et al. (1998) reported an association between the CYP2A6 gene, which codes for the enzyme that metabolizes nicotine to cotinine, and cigarette smoking behavior. We attempted to replicate their findings by analyzing the CYP2A6 gene in a population of 385 individuals using the same two-step PCR assay described by Pianezza et al. but found no association between genotype and either smoking status or cigarette consumption. We then developed a single-step ge PCR method that is specific for the CYP2A6 locus and eliminates a high rate of false-positive mutations detected by the two-step assay. Although this assay gave a much lower frequency of mutant alleles, there was again no association of CYP2A6 genotype with smoking behavior.