The sample consisted of non-Hispanic European American (EA) subjects and Hispanic subjects drawn from the Colorado Center on Antisocial Drug Dependence (CADD). The CADD is a longitudinal study currently in its 3rd wave of data collection consisting of four separate samples. The Family Study (FS) is a sample of clinical adolescent probands, ascertained while in treatment for antisocial drug dependence, their family members, and a matched set of control families (Stallings et al. 2003; Stallings et al. 2005). The Colorado Adoption Project (Petrill SA 2003), the Colorado Longitudinal Twin Study (Rhea et al. 2006), and the Colorado Community Twin Study (Rhea et al. 2006) represent community unselected samples that were used in this study for phenotypic standardization (see below). Only subjects from the FS were included in the molecular genetic study. Briefly, clinical probands were recruited from treatment facilities in the Denver area. Probands were selected from individuals who had consecutive admissions to the treatment facilities between February of 1993 and June of 2001. Controls were recruited from the community and matched to the clinical probands based on age, gender,
