siblings), regardless of sibling phenotypic values. Additional cases and controls were recruited from Cohort 1 participants, and additional Cohort 2 participants, who did not complete the new interview protocol but had comparable alcohol use/dependence assessments. Finally an unassessed population control series is included in some analyses, comprising twins and their families with GWAS data who had participated in an adolescent twin study (29). Further details of the sampling design are given in the Supplemental Methods in Supplement 1. All projects underwent IRB review at the participating institutions. GWAS genotyping, using the Illumina 370K array, was performed on a total of 6852 individuals selected from the BIGSIB and EDAC series (including N=336 parents); from a subsample of the NAG families that had previously been selected for 10cM microsatellite scans (28), and a smaller number of additional alcohol dependent cases and controls from Cohorts 1 and 2. Additional GWAS data are included here for sample members who had been genotyped for other projects (29). Tables S1 and S2 in the Supplement summarize numbers of participants and distribution of sibship size for individuals with GWAS genotyping.
