Participants came from the Collaborative Study on the Genetics of Alcoholism (COGA) [29–31], whose objective is to identify genes involved in alcohol dependence and related disorders. Probands (i.e., index individuals) were identified through alcohol treatment programs at six U.S. sites. Probands and their families were invited to participate if the family was sufficiently large (usually sibships > 3 with parents available) with two or more members in the COGA catchment area. Comparison families were recruited from the same communities. The Institutional Review Boards at all data gathering sites approved this study and written consent was obtained from all participants. COGA data are available via dbGaP (phs000763.v1.p1, phs000125.v1.p1) or through the National Institute on Alcohol Abuse and Alcoholism.
