The Collaborative Studies on the Genetics of Alcoholism (COGA) study's European-American male sample, ascertained for the presence/absence of alcohol dependence, was used for replication of findings. The COGA project, started in 1989, is one of the largest genetic studies of alcoholism and related traits (21,22). Recently, COGA collected a large case-control sample to complement its large multiplex pedigree sample (23). Genome-wide genotypic data are available for this sample. Alcohol-dependent probands were ascertained through alcohol treatment programs and evaluated at seven centers in the United States. The same seven centers also recruited community probands through driver's license records, random mailings to employees and students at a university, and attendees at medical and dental clinics. For the study, a sample of genetically unrelated cases and control subjects were selected from this pool of alcohol- dependent and community ascertained families. As described in Supplement 1, membership in the EA subset was verified using Multidimensional Scaling. The final EA sample included 847 alcohol-dependent cases and 552 control subjects (n = 1399 individuals).
