and GWAS has permitted the discovery of hundreds of genetic variants that alter the risk of developing multiple complex diseases, including type 2 diabetes, Crohn's disease, and Parkinson's disease (Hindorff et al., 2010). More recently, the genetic tools of GWAS have been applied to the study of addiction to identify genetic variations that contribute to this illness. The success of this approach has been in part due to the creation of genetic research consortia for the study of nicotine and illicit drugs (NIDA Genetics Consortium http://www.nida.nih.gov/about/organization/genetics/consortium/index.html) and alcohol (e.g. NIAAA's Collaborative Study on the Genetics of Alcoholism; COGA; http://www.niaaa.nih.gov/ResearchInformation/ExtramuralResearch/SharedResources/projcoga.htm) permitting the collection of the massive numbers of comprehensively assessed subjects and DNA samples required for large scale studies. These resources are also shared with the scientific community though the database of Genotypes and Phenotypes (dbGaP http://www.ncbi.nlm.nih.gov/gap) so that scientists around the world can test new hypotheses about the genetic underpinnings of addiction.
