Genetic predisposition to type 2 diabetes among Asian Indians

Genes play an important role in the development of diabetes mellitus. Type 2 diabetes is a polygenic disorder with multiple genes located on different chromosomes contributing to its susceptibility. Analysis of the genetic factors is further complicated by the fact that numerous environmental factors interact with genes to produce the disorder. Only a minority of cases of type 2 diabetes are caused by single gene defects and one example is maturity onset diabetes of the young (MODY). Till date knowledge of the genetics of type 2 diabetes is limited. Consistent with the complex web of physiologic defects in type 2 diabetes, the genetics of the disorder involves a large number of susceptibility genes, each with a relatively small effect. In this article, the studies on genetics of diabetes in Asian Indians are reviewed. As Asian Indians have an increased susceptibility to diabetes and have increased insulin resistance, they are a unique population for carrying out genetic studies. There appears to be certain genes which predispose Indians to diabetes while other genes (for example Pro 12 Ala polymorphism of PPAR gamma gene) which afford protection against diabetes and insulin resistance to Caucasians, do not appear to protect Indians. Further studies are needed to unravel the genetics of diabetes in South Asians .