Prioritization of families for the COGA family-based GWAS was based on the number of alcohol dependent family members, the number of individuals who supplied DNA and the number of family members with electrophysiological measurements. The family-based GWAS of the theta ERO phenotype only included families of primarily Caucasian descent (to reduce heterogeneity of the sample) and those with measurements of the theta ERO phenotype at the frontal (Fz) lead. Thus, the dataset for the family-based GWAS of theta ERO comprised 1,560 individuals (male=738, female=822) ranging in age from 7 to 74 years (male: 7-74 years, average = 30.7 years; female: 7-72 years, average = 31.6 years) from 117 multi-generational families affected with alcoholism. Family sizes ranged from 4 to 39 individuals and had an average of 13.4 subjects per family (Figure S1).
