Following the approval of institutional review boards at all participating institutions, AD probands > 18 years old were recruited through alcohol treatment programs and administered the adult version of a validated poly-diagnostic instrument, the Semi-Structured Assessment for the Genetics of Alcoholism (SSAGA) (Bucholz et al. 1994). Relatives of the probands and comparison families below the age of 18 years were administered an adolescent version of the SSAGA. The COGA sample used here consisted of 2322 subjects of European descent from 118 extended families with a measure of maxdrinks. The characteristics of the study participants are listed in Table 1. Further details about this dataset, are described elsewhere (Wang et al. 2012a).
