Broadly, two categories of loci were identified. First, in the COGA AA families, loci on chromosome 3, 5, and 13 were GWS and appeared to be attributable to contributions from each individual illicit drug, as well as alcohol dependence. Exclusion of alcohol dependence diagnosis (drug_noalc) resulted in nominal significance in all three regions, despite the substantially reduced sample size and power. Thus, these loci may represent genetic liability that is common to alcohol and illicit drug dependence that cannot be entirely attributed to alcohol dependence. On the other hand, the locus on chromosome 1 which was GWS in the COGA EA+AA analysis and was supported by signals in both the EA and AA subsamples, showed nearly no evidence for association in the drug_noalc analyses (p=0.04; and only in the AA families), suggesting that this signal is primarily due to alcohol dependence. In EAs, this genome-wide significant SNP (rs1890881) is in perfect LD with rs61826952 which was genome-wide significant in the COGA GWAS of DSM-IV alcohol dependence (COGA EA+AA p=8.4E-11; see accompanying paper by Lai et al.). The r2 in the
