First study of the genetic links to diabetes in South Asians finds six new variants

In an international research effort led by Imperial College London, scientists have identified six new genetic variants linked to type 2 diabetes (T2D) in South Asians.

'Our findings give important new insight into the genes underlying diabetes in this population, which in the long term might lead to new treatments to prevent diabetes', said senior author of the study, Dr John Chambers from the School of Public Health at Imperial College London.

Unhealthy diet, obesity and physical inactivity are important risk factors for T2D, but scientists believe there is also a genetic contribution. Previous studies investigating the genetic susceptibility to T2D have been predominantly performed in populations of European descent, with 42 genetic associations previously identified.

However, those with South Asian ancestry are up to four-times more likely to develop T2D than Europeans. T2D currently affects around 55 million South Asians worldwide, and this figure is predicted to rise to 80 million by 2030.

The reason for this is unclear, says Dr Chambers. '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', he said.

The team of international researchers from the UK, India, Singapore, Pakistan, Mauritius and Sri Lanka, used genome-wide association studies to identify common genetic variants underlying predisposition to T2D in South Asians.

The scientists examined the DNA of 18,731 people with type 2 diabetes and analysed the genome for locations where variations were more common in those with diabetes. The data revealed six positions where differences of a single letter in the genetic code were associated with type 2 diabetes, suggesting that nearby genes (GRB14, ST6GAL1, VPS26A, AP3S2, HMG20A and HNF4A) may have a role in the disease.

'Our study identifies six new genetic variants linked to type 2 diabetes in South Asians', said Dr Chambers.

The scientists also showed that the new genetic links to T2D in South Asians are also important in European populations. The lead author, Professor Jaspal Kooner from the National Heart and Lung Institute at Imperial College London, said: '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 results were published in Nature Genetics.