Bierut et al., 2010 conducted a GWAS that examined a well-characterized sample of 1897 DSM-IV alcohol dependent cases and 1932 alcohol-exposed, non-dependent controls from the Study of Addiction: Genetics and Environment (SAGE) (Bierut et al., 2010). The SAGE discovery sample consists of three large, complementary datasets: the Collaborative Study on the Genetics of Alcoholism (COGA), the Family Study of Cocaine Dependence (FSCD), and the Collaborative Genetic Study of Nicotine Dependence (COGEND). Approximately, 950,000 SNPs were analyzed that span the entire genome. About 60% of the cases were male. Roughly 70% of the sample were from European descent and 31% African-American ancestry. A small number of subjects (3%) reported Hispanic ethnicity. Almost half of the alcohol-dependent sample were diagnosed with comorbid marijuana or cocaine dependence. Comorbid substance dependence in half of the cases is an important factor to consider when interpreting the results of this study. In the discovery sample no single SNP met the genome wide significant threshold of p < 10–8. However, the authors selected 15 SNPs with p < 10–5 for further analyses in two replication samples. Of these 15 SNPs several are worth highlighting for functional relevance with the addiction cycle.
