Six new genetic variants linked to type 2 diabetes discovered in South Asians
30 August 2011
People of South Asian ancestry are up to four times more likely than Europeans to develop type 2 diabetes, which is a major risk factor for heart disease and stroke. Around 55 million South Asian people are affected worldwide, and the number is projected to rise to 80m by 2030.
This new study is the first to focus on genes underlying diabetes among people originating from South Asia (India, Pakistan, Sri Lanka and Bangladesh). The researchers examined the DNA of 18 731 people with type 2 diabetes and 39 856 healthy controls. The genomes of the participants were analysed to look for locations where variations were more common in those with diabetes. The results identified six positions where differences of a single letter in the genetic code were associated with type 2 diabetes, suggesting that nearby genes have a role in the disease.
Type 2 diabetes is more common in South Asian populations than any other ethnic group, but the reason for this increased risk is unclear. Although lifestyle factors such as unhealthy diet, physical inactivity and obesity are important causes of diabetes in South Asians, these are only part of the explanation. Genetic factors have been widely considered to play a role in the increased risk of type 2 diabetes in Asians, but to date have not been systematically explored in this population.
Dr John Chambers, senior author of the study, from Imperial College London, said: "Our study identifies six new genetic variants linked to type 2 diabetes in South Asians. Our findings give important new insight into the genes underlying of diabetes in this population, which in the long term might lead to new treatments to prevent diabetes."
Professor Jaspal S Kooner, lead author for the study, also from Imperial, said: "This is the first genome-wide association study in South Asians, who comprise one-quarter of the globe's population, and who carry a high burden of the disease and its complications, including heart attack and stroke. We have shown that the genetic variants discovered here in South Asians also exist and contribute to diabetes in Europeans. Our studies in Asians and European populations highlight the importance and gain in examining the same problem in different ethnic groups."
The research was funded by the Imperial Comprehensive Biomedical Research Centre award from the National Institute of Health Research, the Medical Research Council, the Wellcome Trust and other sources.
Image: A busy street in India. Credit: Carol Mitchell on Flickr
Reference
Kooner JS et al. Genome-wide association study in people of South Asian ancestry identifies six novel susceptibility loci for type 2 diabetes. Nat Genet 2011 28 August [epub].