other lines of evidence to prioritize potential candidates. Regions in which several SNPs provided evidence for association were found. Evidence of association, with similar estimates of effect size (odds ratios), was found for many SNPs when the sample of alcohol dependent individuals was dichotomized and only those with early onset alcohol dependence were defined as cases. Early onset generally marks a group of more severe cases, often with comorbid psychiatric problems. Analyses of this subgroup have yielded smaller p values, despite the reduced sample size, in some previous studies (Agrawal et al., 2006; Dick et al., 2007a; Edenberg et al., 2008b; Foroud et al., 2008). We assessed segregation within alcohol dependent families as a means to prioritize among our SNP results. We also used gene expression data as additional lines of support, testing whether a gene in or nearest the SNP was expressed in human brain samples. We tested whether the expression of the gene in LCLs was altered by ethanol exposure; 80% of the genes differentially expressed in LCLs after ethanol exposure are also expressed in at least one of the 9 brain regions we analyzed (Edenberg et al., in preparation).
