In the present study, we extended these twin study results to examine the relationship between these measures of alcohol use/problems and DRD2/ANKK1. We hypothesized that examining association with genetic factor scores (previously implicated by the twin analyses within the same sample) would decrease the genetic heterogeneity and consequently increase power to detect genetic association between DRD2/ANKK1 and alcohol outcomes. We were primarily interested in the shared genetic variance across all alcohol measures (Figure 1. latent genetic factor A1) and the shared genetic variance across the two indices of problematic alcohol use (Figure 1. latent genetic factor A6). Additionally, we conducted post hoc analyses of the association between DRD2/ANKK1 and multiple measures of both alcohol consumption and problems in an effort to evaluate whether using genetic factor scores was an improvement upon using individual measures of alcohol consumption and problems.
