Rapid advances in genetic technology now provide a set of tools to identify genetic contributions to common diseases. A map of human genetic variation across major populations and lower cost testing of genetic variants allow large-scale genome-wide association studies (GWAS) that test one million or more genetic variants (single nucleotide polymorphisms or SNPs) in each person. These studies, which include thousands of subjects, test hundreds of thousands of variants across an individual’s complete set of DNA to identify genetic variations associated with a disease. In the last three years this has led to the discovery of new genetic contributions to diabetes, prostate cancer, and many other diseases, including nicotine dependence [11].
