Several genome-wide association studies (GWAS) examining the risk for alcohol dependence have been completed using a variety of designs, including case- control series of male alcoholics recruited from inpatient treatment facilities (125), individuals selected from densely affected families with alcohol dependence (35), a mixed case-control series drawn from treatment- and community-based samples (14), subjects ascertained from community-based sibships, and individuals selected for heavier alcohol use (61). GWAS using quantitative traits derived from alcohol-consumption and alcohol-dependence symptomatology have also been examined in controls from a population-based sample recruited for schizophrenia (73) and an Australian population of related individuals (61). One study identified two correlated intergenic single-nucleotide polymorphisms (SNPs) on human chromosome 2q35 that met genome-wide significance in the combined analysis of the GWAS and follow-up data sets (125). The other studies did not observe any association that met conventional genome-wide significance, and the overlap of the top genetic signals across studies has been limited.
