Polymorphisms on 7p14, 8p11, 10q23, 15q25, and 19q13 have been associated with smoking behavior in GWAS, typically measured as CPD (6-8,12,13). However, in this study we did not detect any associations between previously implicated SNPs and CPD (Table 3), possibly due to the limited sample size. Indeed, the statistical power to detect the expected effect of SNPs on CPD ranged from 10% to 60% for the variants studied. Conversely, SNPs on 15q25 were clearly associated with cotinine levels, as well as lung cancer risk, consistent with the expected direction of association noted in the original GWAS. Similarly, an association with cotinine levels and other nicotine metabolites was previously described for the 15q25 locus (43). with the effect being stronger for cotinine than CPD(36).
