Genomewide Association Studies and Assessment of the Risk of Disease

Abstract

Genomewide association studies — in which hundreds of thousands of single-nucleotide polymorphisms (SNPs) are tested for association with a disease in hundreds or thousands of persons ( Figure 1 ) — have revolutionized the search for genetic influences on complex traits.^1,2 Such conditions, in contrast with single-gene disorders, are caused by many genetic and environmental factors working together, each having a relatively small effect and few if any being absolutely required for disease to occur. Although complex conditions have been referred to as the geneticist's nightmare,³ in the past 5 years genomewide association studies have identified SNPs implicating hundreds of robustly replicated loci (i.e., specific genomic locations) for common traits.⁴