A study in which specific genetic markers (usually SNPs) across the entire genome of multiple people are scanned in order to find genetic variations associated with disease. By comparing DNA samples from a group of patients who share a particular genetic disease to those who do not, genome-wide association studies aim to pinpoint the genetic differences that correlate with and perhaps play a causative role in that disease.
Genome-wide association studies (GWAS) compare genetic variants in very large populations of people with a particular disease with those who do not have the condition. Genetic variants found at an increased frequency in people with a particular condition compared with people without the condition are said to be "associated" with the condition. Further studies are undertaken in the area of the genome containing the variant to find genes that may increase susceptibility or give protection to the condition.
For example, in June 2007, the Wellcome Trust Case Control Consortium reported the localisation of 24 new susceptibility loci using the GWAS approach and studying half a million genetic variants in 17,000 people. The conditions were bipolar disorder, coronary artery disease, Crohn's disease, rheumatoid arthritis, and types 1 and 2 diabetes.
By March 2010, 779 areas of the genome implicated in 148 common diseases and traits had been identified in the published literature. Much of this information requires further assessment before its place in clinical management is justified, but the amount of information becoming available is increasing dramatically.
