The most significant SNP reported in this region, the intergenic variant rs41405144, lies within two large deletions (defined as CYP2a6*4 and CYP2a6*12). This variant, rs41405144, is correlated with rs1801272, a non-synonymous SNP that defines the CYP2a6*2 loss of function allele. These findings confirm that variation in nicotine metabolism contributes to the number of cigarettes smoked daily and the development of nicotine dependence.
