In this study we tested gene - environment interactions for risk of nicotine dependence between nicotinic receptor gene SNPs and reported number of H.S. peers who smoked. Significant main effects were observed for H.S. peer smoking and each of the four SNPs examined rs16969968 and rs578776 in the CHRNA5-CHRNA3-CHRNB4 gene cluster, rs13277254 tagging CHRNB3-CHRNA6 and rs12466358 in the CHRND gene. The statistically significant interaction between rs16969968 and H.S. peer smoking (p = 0.0077) indicated that the impact of H.S. peer smoking on the probability of nicotine dependence was substantially reduced among those with the highest risk genotype (AA).
