Introduction: Type 2 diabetes (T2D) is a complex disease caused by an interaction between multiple genetic and environmental factors. T2D-associated loci identified by genome-wide association studies (GWAS) harbor the genes targeted by many clinically available drugs, supporting the idea that GWAS have the potential to discover novel genes for drug development.
Areas covered: This paper outlines, among the genes at those T2D-associated loci, the functional analysis of FTO, TCF7L2, SLC30A8, and MTNR1B, illustrating caveats we should be cautious about. This paper also reviews the current status of the compounds targeting the T2D-associated genes GCK, GKRP, ADIPOQ, and ADRA2A in clinical and preclinical phases.
Expert opinion: Functional analysis of those loci has fallen too far behind identification of T2D-associated loci. It is mandatory to define the true causal gene at the T2D-associated loci by using a variety of experimental techniques. The biggest challenge lies in the limited access to human tissues relevant to the pathogenesis of T2D. The ultimate goal of human genetic study is enabling personalized medicine based on the genetic information of individuals. More research will be needed to achieve this goal.
Keywords: GWAS; association; causal variant; genetic variant; molecular target; nonsynonymous variant; regulatory variant; type 2 diabetes.