New Delhi: Scientists in India have, for the first time, identified a genetic variation that could explain why north Indians are susceptible to type-2 diabetes, the most common variant of the illness.
The study, to be published in the peer-reviewed Journal of Human Genetics, was conducted by scientists from the New Delhi-based Institute of Genomics and Integrative Biology, or IGIB, and the All India Institute of Medical Sciences, also in the Capital. IGIB is part of the Council of Scientific and Industrial Research, or CSIR.
The study is part of a larger, ongoing CSIR project to unravel the molecular mechanism and genetic factors underlying diabetes in India.
Type-2 diabetes is a condition in which the body becomes resistant to insulin, a hormone that regulates blood sugar levels, and stores abnormally large quantities of glucose.
Diabetes — which according to a recent study by industry lobby Assocham is projected to afflict 57 million Indians by 2025 and has been classified as an epidemic by the US’ Centre for Disease Control — is a chronic, incurable disease. Identifying genes can help early detection; together with a proper diet and exercise, it can greatly reduce the risk of diabetes-related complications such as heart disease and hypertension. Though studies have shown that type-2 diabetes is more prevalent in south Indian than north Indian populations, the south Indian gene pool being relatively more heterogeneous (many different genes may be associated with one effect) makes it harder to pinpoint genetic culprits.
Though the findings don’t change the well-known thesis that obesity and poor diet are the most common causes of diabetes, researchers across the world are exploring specific genes that are responsible for diabetes. International teams have discovered as many as 17 genes that are closely linked with the onset of diabetes, but none has proved to be causative.
“We’ve essentially shown that specific polymorphisms (variants) of the FOXA2 gene are strongly linked with diabetes in India,” said Dwaipayan Bharadwaj, a senior scientist at IGIB and one of the authors of the study. “Though the study spanned 1,656 people, mostly from in and around Delhi, we need to further study populations in the south, for example. But we are confident that we can extrapolate these studies to large swathes of India.”
The FOXA2 gene is a well-known regulator of pancreas development and insulin sensitivity. Though researchers have suspected that the gene may have a role in the onset of diabetes, it is necessary to know what specific variant (or polymorphism) of the gene may be responsible for a certain condition.
“It’s a very useful study, especially because now there is increasing evidence that rare polymorphisms (those not widely distributed in ethnic populations) may have a large effect in triggering diabetes among certain groups,” said Mark McCarthy, a professor of diabetes at the Oxford Centre for Diabetes, Endocrinology and Metabolism, UK.