Fine mapping type 2 diabetes susceptibility loci

© 2014 S. Karger AG, Basel. Genome-wide association studies of type 2 diabetes have been extremely successful in identifying loci contributing genetic effects to disease susceptibility. These loci often extend over hundreds of kilobases, contain many transcripts, and encompass hundreds of variants, many of which have the potential for direct functional impact on the disease. Consequently, the pathophysiological mechanisms underlying disease susceptibility remain obscure. In this review, we consider a range of approaches for assaying genetic variation across complex human trait loci, and discuss available methodology for fine-mapping causal variants within these regions. We then consider progress in fine-mapping type 2 diabetes susceptibility loci, evaluating the evidence for allelic heterogeneity arising from multiple causal variants at the locus, interpretations of the underlying genetic architecture of the disease, and the utility of functional annotation and biological resources to improve localisation.