We obtained the individual level SAGE GWAS dataset from the database of Genotypes and Phenotypes (dbGaP). SAGE aims to identify genetic risk factors and the interplay of genes and environmental factors for addiction. Cases and controls were selected from three large, complementary cohorts: 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), all of which have been previously described (33–36). The current study included 4036 unrelated self-reported AA (1297 in total including 275 CaD and 422 healthy controls) or EA (2740 in total including 401 CaD and 1049 healthy controls) subjects. Lifetime CaD was defined in accordance with the DSM-IV diagnosis. Controls used for association analysis in the current study were defined as subjects without dependence on any substances, including cannabis, alcohol, cocaine, opioid, nicotine, and other substances.
