SNPs in the CHRNA5-CHRNA3-CHRNB4 gene cluster on chromosome 15 were selected for study. We targeted this region because of recent findings of strong association between SNPs across this cluster and nicotine dependence. In particular, here we have focused on a non-synonymous coding SNP in CHRNA5, rs16969968, and its genetic correlates, that is, SNPs having high r2 with it. This SNP has demonstrated strong association with nicotine dependence [6,10] and has recently been replicated in independent samples, either through analysis of the same SNP [11] or proxy SNPs having very high r2 with it [12,13]. This SNP or its r2 proxies have now also demonstrated association with lung cancer [13-15].
