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 prior reports.40,42 Our investigation provides strong evidence of association of individual ANKK1 and TTC12 SNPs with heroin and other illicit drug dependence, replicating findings in a prior report.42 Despite these converging findings, considerable variation in the intensity and location of association was found across reports.38–40,42–46 Differences in examined phenotype likely contributed to this variance because alcohol- and nicotine-related outcomes differ but are significantly correlated.
