Data were from the Study of Addiction: Genetics and Environment (SAGE), which is part of the National Human Genome Research Institute's Gene Environment Association Study Initiative (Database for Genotypes and Phenotypes (dbGaP) study accession phs000092.v1.p1). SAGE is a multi-ethnic sample of 4121 unrelated individuals from three large, complementary datasets designed to study drug addiction: the Collaborative Study on the Genetics of Alcoholism (COGA), the Family Study of Cocaine Dependence (FSCD), and the Collaborative Genetic Study of Nicotine Dependence (COGEND). Subjects in COGA were recruited from several sites throughout the United States of America by identifying alcoholic probands from treatment facilities and recruiting other family members, as well as comparison families from the same communities. COGA subjects utilized in the current study are a case-control subset of independent individuals. The FSCD is a case-control family study that ascertained cocaine dependent individuals from chemical dependency treatment units in the greater St. Louis metropolitan area along with community-based control subjects matched on several criteria such as age and race. The COGEND is a community-based case-control family study that recruited nicotine dependent cases and
