In an attempt to replicate and extend these findings, we focused our attention upon phenotype associations for the top 25 SNPs tested with nicotine dependence by Bierut et al. Before analysis, we decided to test rs16969968 a priori, and then examine the other 24 SNPs. Unlike the Bierut et al. study, in which both cases and controls were smokers, the current study involved a control group of life-time never-smokers who had taken at least one puff from a cigarette (to ensure that they had actively rejected cigarette smoking). Also unlike that study, our sample included a small, exploratory sample of African American participants in addition to the larger sample of Caucasians.
