different effects among different ethnic groups, consistent with the fact that in animal models, the effect of a gene deletion may differ depending on genetic background (Crabbe et al, 2006). In this NYS sample of adults, results from the DSM-IV analyses in the sibpairs sample suggest that SNP rs2304297 in CHRNA6 is associated with nicotine dependence (in Caucasians) and number of unsuccessful quit attempts. This SNP has been examined for its involvement in nicotine dependence in all of the other studies. Greenbaum et al (2006) did not find any evidence for association, as measured by FTND. However, results from a genome-wide association (Beirut et al, 2007), as well as a candidate gene study (Saccone et al, 2007) in the same sample, revealed a highly significant association between FTND-defined nicotine dependence and the same risk allele associated in this paper (G). Although Zeiger et al (2008) did not find evidence for association with nicotine dependence, there was suggestive evidence for association between rs2304297 and early subjective response to tobacco in both samples studied. Each of these samples consisted of adolescents/young adults (mean ages of 18.21 ± 1.5 and 22.4 ± 1.7), as was the relatively small sample in the Greenbaum et
