Samples for this meta-analysis were drawn from three existing studies, the Collaborative Study on the Genetics of Alcoholism (COGA), the Collaborative Genetic Study of Nicotine Dependence (COGEND), and the Family Study of Cocaine Dependence (FSCD), each of which is described below. For purposes of this study, all case subjects met a lifetime diagnosis for DSM-IV alcohol dependence8. Control subjects had at least one drink of alcohol, but never met dependence for DSM-IV alcohol dependence. Characteristics of adult subjects from COGA, COGEND and FSCD are presented in Table 1.
