We used data from the Prospective Study sample of the Collaborative Study on the Genetics of Alcoholism (COGA), which has the goal of identifying genetic influences on alcohol dependence and related psychiatric outcomes (Begleiter et al. 1995). COGA recruited 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), from inpatient and outpatient alcohol treatment centers across six study sites in the United States. Population-based comparison families were also recruited. The Institutional Review Boards of all participating institutions approved the study, and written consents were obtained from all participants. Information about the design of the COGA study is described in more detail in previously published papers (Begleiter et al. 1995; Foroud et al. 2000; Reich et al., 1998).
