We used data from the Prospective Study sample of the Collaborative Study on the Genetics of Alcoholism (COGA). COGA is a collaborative research project between multiple sites in the US, with the goal of identifying genetic influences on alcohol use disorders and related psychiatric outcomes (Begleiter et al., 1995). Families with alcohol dependent probands, based on 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), were recruited from inpatient and outpatient alcohol clinics across six study sites in the US and followed longitudinally. Unascertained comparison families from the population were also recruited from various sources (e.g., driver’s license records and dental clinics). The Institutional Review Boards of all participating institutions approved the study, and written consents were obtained from all participants. Detailed description about the design of COGA can be found in previously published papers (Begleiter et al., 1995; Foroud et al., 2000; Reich et al., 1998).
