Data for this study come from the Study of Addiction: Genes and Environment (SAGE),27 which was one of the eight phase 1 studies in the Gene Environment Association (GENEVA) consortium.28 Cases and controls for the SAGE sample were drawn from three contributing projects: the Collaborative Study on the Genetics of Alcoholism (COGA),29 the Collaborative Study on the Genetics of Nicotine Dependence (COGEND)30 and the Family Study of Cocaine Dependence (FSCD). Although cases in these studies were ascertained for alcoholism, nicotine dependence (based on an FTND score of ≥4 in current smokers, controls being smokers) and cocaine dependence, respectively, cases for SAGE were uniformly defined as those meeting DSM-IV criteria for alcohol dependence (N= 1899). Controls (N= 1946) were unrelated individuals who were largely past the highest risk period for developing alcohol dependence, and who reported drinking alcohol but not meeting criteria for alcohol dependence at any time during their life. An additional 143 subjects who met criteria for dependence on illicit drugs but not for alcohol dependence were also genotyped and included in this study.
