We extracted candidate SNPs achieving genome-wide significance in the previous studies on smoking cessation and CPD.8–1126 Following previous GWAS,89 we additionally extracted two SNPs from CYP2A6 (rs1801272 (Leu160His)) and CHRNA5 (rs588765) based on their biological function. Since a candidate SNP from the DBH locus and most of the candidate SNPs from the CYP2A6 locus were imputed in all cohorts, we searched for the best proxy SNP genotyped in at least 3 of the cohorts.
