on power for gene identification studies (Manchia et al., 2013), so even smaller studies such as this can provide insight into potential challenges to consider when designing large scale efforts in the future. Indeed, though gene identification efforts for alcohol-related outcomes are still in their infancy compared to some other complex traits, our results fit into the emerging pattern of results demonstrating that different genes and genetically correlated traits appear to be linked to alcohol problems in ascertained and population studies (Hart and Kranzler, 2015; Sanchez-Roige et al., 2017; Schumann et al., 2016: Walters et al., in preparation). Such studies should consider testing for heterogeneity as a function of population type (in addition to several other sample characteristics) when meta-analyzing across multiple samples to confirm or refute the suggestive results found here.
