Many genome-wide association studies (GWAS) have been conducted for diagnostic alcohol outcomes (e.g., alcohol abuse/dependence or symptom count; Treutlein et al., 2009a; Bierut et al., 2010; Edenberg et al., 2010; Kendler et al., 2011b; Wang et al., 2013; Gelernter et al., 2014). Overall, these investigations have not enjoyed the same success in large-scale gene-identification efforts as, for example, schizophrenia (Schizophrenia Working Group of the Psychiatric Genomics Consortium, 2014). Quantitative phenotypes are more statistically powerful than binary outcomes in general population samples and have also been the subject of recent genome-wide studies (e.g., Heath et al., 2011; Schumann et al., 2011; Pan et al., 2013; Kos et al., 2014; Edwards et al., 2015). In some cases, associations surpassing stringent genome-wide significance criteria have been observed (Schumann et al., 2011; Pan et al., 2013), though robust replication has not been reported.
