Single marker analysis showed that 3 SNPs (rs8192729, rs7256108, and rs7255443) in the CYP2A6 gene were associated with class I obesity (p<0.05) (Table 1). The most significant SNP for obesity was rs8192729 (OR=1.94, 95%CI=1.21–3.10, p=5.82×10−3). The SNP rs7251418 revealed a borderline association with class II and III obesity (OR=1.34, 95%CI=0.96–1.87, p=0.0878). The pairwise LD statistics (r2) for 10 SNPs were assessed for controls with normal weight using HAPLOVIEW (Supplemental Figure 1). Rough rule of thumb, values of r2 >1/3 might indicate sufficiently strong LD to be used for fine mapping (ref. 23). Table 2 shows eight haplotypes associated with class I obesity. The A-G haplotype from rs8192729-rs7256108 (r2 = 0.94 between the two SNPs) and the A-T haplotype from rs8192729-rs7255443 (r2 = 0.94 between the two SNPs) showed the most significant associations with class I obesity (p = 5.82 ×10−3). These results suggest that CYP2A6 gene is associated with obesity in human, especially class I obesity.
