This analysis uses a subset of subjects who have ever smoked from the Study of Addiction: Genetics and Environment (SAGE), part of the Gene Environment Association Studies (GENEVA) program of the National Institutes of Health (NIH) Genes, Environment, and Health Initiative(23). For the overall SAGE project, unrelated alcohol dependent cases (N = 1,897) and non-alcohol dependent control subjects (N = 1,937) were selected from three large, complementary datasets: Collaborative Genetic Study of Nicotine Dependence (COGEND), Collaborative Study on the Genetics of Alcoholism (COGA), and Family Study of Cocaine Dependence (FSCD). Characteristics of the individual datasets are given in supplementary Table 3. The Institutional Review Board at each contributing institution reviewed and approved the protocols for genetic studies of substance dependence under which all subjects were recruited. Subjects provided informed consent for genetic studies and agreed to allow their genetic and phenotypic information to be shared with qualified investigators through NIH repositories. For each of the three studies, we describe the sampling schemes used to recruit subjects and select for genotyping.
