Our focus on AAs both strengthened and limited the study. Few prior studies have focused on phenotyping harmful alcohol use for genetic discovery among AAs. However, our sample was large enough to examine the validity of the AUDIT-C only in AAs. Because another ADH1B missense polymorphism, Arg48His, has been shown to be protective from alcohol dependence in Asians (Li et al., 2011) and European Americans (Bierut et al., 2012, Gelernter et al., 2014), the same approach could be used to evaluate the AUDIT-C in these populations. Despite being limited to one population, the findings reported here indicate that longitudinal AUDIT-C data provide a valid metric of harmful alcohol use that may be a useful phenotype for genetic discovery. Because the AUDIT-C is a widely used screening measure, when administered as a repeated metric of harmful drinking, it may provide an important source of phenotypic information for large-scale genetic studies.
