In our total sample containing 840 subjects, the nine SNPs achieved p values at levels of 10−5 to 10−6 for association with smoking status, with the most significant SNP, rs4956302, reaching a p value of 1.19 ×10 −6 (Table 2). We further performed gender-specific association analyses (adjusted for age) for these nine SNPs and found that these SNPs were associated with smoking status much more strongly in males than in females, showing an apparent male-specific association (Table 2). In males, association of these SNPs with smoking status achieved significance levels similar to that seen in the total sample despite the fact that the number of male subjects was approximately one half of the total. In particular, rs4956302 achieved a p value of 8.08 × 10−8 in males, which is significant at the genome-wide level (Table 2).
