The samples included in this study were recruited and tested as part of the Collaborative Study on the Genetics of Alcoholism (COGA), a large multi-site national study implemented with the purpose of identifying genetic loci linked with the predisposition to develop alcoholism and other related disorders. Data from six COGA sites were included in the analysis: SUNY Downstate Medical Center, Brooklyn, New York; University of Connecticut Health Science Center; Indiana University School of Medicine; University of Iowa School of Medicine; University of California School of Medicine, San Diego; and Washington University School of Medicine, St Louis. Ascertainment and assessment procedures have been outlined previously (Begleiter and others 1995; Foroud and others 2000; Nurnberger and others 2004; Reich and others 1998).
