GWA (genome-wide association, GWAS)

GWAS uses mapping linkage to the level of expression across a genome(s). The analysis may involve various markers, including single-nucleotide polymorphism, and determines the regression of the markers and the trait of interest (Evans DM, Cardon LR 2006 Trends Genet 22:350). Statistical and computer programs are now available for studying the association between known phenotypes and molecular biology markers (Pearson JW et al 2007 Amer J Hum Genet 80:126). This relatively new approach is less expensive for the analysis of complex traits than direct genotyping although it may be adversely affected by microarray-based errors (McGregor S 2007 Eur Hum Genet 15:501). A GWA study of British populations in 2007, including 2,000 individuals for each of seven major diseases and a shared set of 3,000 controls, identified 24 independent association signals at P < 5 x10⁻⁷: one in bipolar disorder, one in coronary artery disease, nine in Crohn’s disease, three in rheumatoid arthritis, seven in...