We completed a genome-wide association study (GWAS) to identify genes contributing to alcohol dependence, defined according to DSM-IV criteria (American Psychiatric Association, 1994). Both the alcohol dependent cases and the controls have completed a rigorous clinical evaluation, with controls being drinkers who are free from alcohol dependence or abuse by several diagnostic classification systems (DSM-IIIR, DSM-IV, ICD-10) (American Psychiatric Association, 1987; American Psychiatric Association, 1994; World Health Organization, 1993), and also free of dependence on illicit drugs. To prioritize among the most promising single nucleotide polymorphisms (SNPs) identified from the GWAS, we genotyped the top SNPs in a sample of alcohol dependent families and performed family based association analysis, and tested whether they fell within or near genes whose expression is affected by alcohol exposure, and were expressed in brain.
