The case-control GWAS subsample was selected from the collaborative study on the genetics of alcoholism (COGA) as previously described (Edenberg et al. 2010). COGA recruited families with alcohol dependent probands diagnosed as alcohol dependent by both the diagnostic and statistical manual of mental disorders, third edition, revised (DSM-III-R) (American Psychiatric Association 1987) and Feighner criteria (Feighner et al. 1972) from inpatient and outpatient alcohol treatment centers across study sites, and families from community controls. A poly-diagnostic instrument, the semi-structured assessment for the genetics of alcoholism (SSAGA) (Bucholz et al. 1994; Hesselbrock et al. 1999) was administered to participants. Written consents were obtained from all participants, and the institutional review boards of all participating sites approved the study. Cases were selected from families with alcohol dependent probands that had a lifetime AD diagnosis using DSM-IV (American Psychiatric Association 2000) criteria. Controls were selected from both community-ascertained families and families with alcohol dependent probands, but could not share a common known ancestor with a case subject. Controls were required to have previously consumed alcohol, but not to have a diagnosis of alcohol
