In contrast to linkage studies, association studies can identify
variants with relatively small individual contributions to
disease risk
z However, they require detailed measurement of genetic
variation and there are >10,000,000 catalogued genetic variants
z Until recently, studies limited to candidate genes or regions
• A hit-and-miss approach…
z Because assay costs are decreasing and a modest number of
variants can represent all others, genome-wide association
studies are now possible.