Recently, investigators from the Collaborative Studies on Genetics of Alcoholism (COGA) conducted an enrichment analysis of single nucleotide polymorphisms (SNPs) in a set of over 100 genes, which were selected because of evidence that they were associated with alcohol outcomes in either GWAS or candidate gene analyses (Aliev et al., 2015). Consistent with results from previous twin research (e.g., Krueger et al., 2002), Aliev and colleagues found significant enrichment of associations not only with alcohol dependence symptoms, but also with antisocial behavior symptoms, conduct disorder symptoms, and sensation seeking personality. As these outcomes were tested individually as separate observed measures, the enrichment results observed for these outcomes could be interpreted in one of two ways. First, these genetic variants could influence biological processes that underlie all of the different symptoms. For example, an individual with genetic variants that predisposed them to greater reward sensitivity may be more sensation seeking, more likely to use drugs, and more likely to have break rules to obtain desired ends. Alternatively, the gene set could be heterogeneous, with some variants affecting only alcohol use, some
