association). Further analyses implicated a 4-SNP haplotype spanning TTC12 and ANKK1. They later focused40 on alcohol dependence in two European American samples, finding only nominally significant associations for individual SNPs; haplotype-based analyses observed significant associations centering on TTC12, NCAM1, and ANKK1. A subsequent examination42 found that risk associated with most of these haplotypes was for comorbid alcohol and illicit drug dependence rather than alcohol dependence alone. In Collaborative Study on the Genetics of Alcoholism (COGA) family data,39 nominal associations for alcohol-related phenotypes were found in an overlapping ANKK1 region (including both rs877138 and rs4938012). A Collaborative Study on the Genetics of Alcoholism genome-wide association study (COGA GWAS)45 found that rs10502172, a more upstream TTC12 SNP, was nominally associated with alcohol dependence (p=7.0 × 10−4). A Finnish population-based birth cohort study46 reported strong association of SNPs within a haplotype block stretching from TTC12 to DRD2 (including rs877138; p=.001) with smoking at age 14 years; rs10502172 (p=9.1 × 10−6) was most highly associated. These SNPs were more weakly associated with smoking at age 31 years. Overall, our association signal extensively overlaps those of reports focusing on nicotine- and alcohol-related phenotypes;38,39,46 the weaker, independent association with the NCAM1 SNP rs4492854 is consistent with
