Subjects were collected at six centers in the United States: Indiana University, State University of New York Health Science Center, University of Connecticut, University of Iowa, University of California/San Diego, and Washington University, St. Louis. The institutional review boards of all participating institutions approved the study. Probands were identified through alcohol treatment programs. After providing informed consent, probands and their relatives were administered a validated poly-diagnostic instrument, the Semi-Structured Assessment for the Genetics of Alcoholism (SSAGA) interview (Bucholz et al., 1994; Hesselbrock et al., 1999). For ascertainment, alcoholism was defined as meeting criteria for both DSM-IIIR alcohol dependence (American Psychiatric Association 1987) and Feighner definite alcoholism (Feighner et al., 1972) (this combination is called COGA criteria). Details of the ascertainment and assessment have previously been published (Begleiter et al., 1995; Foroud et al., 2000; Reich et al., 1998) and are available in detail at zork.wustl.edu/niaaa/coga_instruments/resources.html. Families in which at least 3 first-degree relatives were alcohol dependent participated in the genetic part of the COGA study, as described in more detail by Foroud et al. (Foroud et al., 2000). A sample of 1923 European American individuals from 219 alcoholic families was used in this study.
