Participants came from the Collaborative Study on the Genetics of Alcoholism (COGA).19 The primary goal of COGA is to identify genes involved in alcohol dependence and related disorders. Alcohol-dependent probands were identified through alcohol treatment programs at seven US sites and were invited to participate if they had a sufficiently large family (usually sibships >3 with parents available) with two or more members in the COGA catchment area. Community probands and their families were recruited through driver's license records, mailings to randomly selected employees and students at a university, and attendees at medical and dental clinics. The institutional review boards at all sites approved this study and written consent was obtained from all participants. The present study included the participants in the European-American subset from the COGA case–control GWAS sample (in which cases met Diagnostic and Statistical Manual of Mental Disorders, 4th Edition (DSM-IV) alcohol dependence criteria20) for whom adult antisocial behavior interview data were also available (n=1379; 739 (54%) male and 640 (46%) female). European ancestry was determined using a principal-component-based analysis in PLINK.20 The average age at assessment was 43.8 years (s.d.=11.7; range=18–79).
