John von Radowitz

A section of genetic code has been linked to expanded waistlines, excessive weight, and a tendency to develop diabetes.

The DNA sequence is significantly more common in people with Indian Asian rather than European ancestry, say researchers. They hope the findings will lead to better ways of treating obesity.

Study leader Professor Jaspal Kooner, from the National Heart and Lung Institute at Imperial College London, said: "Until now, we have understood remarkably little about the genetic component of common problems linked with obesity, such as cardiovascular disease and diabetes.

"Finding such a close association between a genetic sequence and significant physical effects is very important, especially when the sequence is found in half the population."

The sequence is associated with a 2cm expansion in waist circumference, a 2kg gain in weight, and a tendency to become resistant to the effects of insulin, which can lead to Type 2 diabetes.

Indian Asians are one-third more likely to have the sequence than people of European descent, the scientists found.

This was thought to provide one explanation for unusually high levels of obesity and insulin resistance among Indian Asians, who are expected to account for 40% of global heart disease by 2020.

The sequence is not a gene, a piece of DNA that provides the coded instructions for making a specific protein. But it sits close to a gene called MC4R, which regulates energy levels in the body by influencing how much we eat and how much energy we expend or conserve.

It may be that the sequence plays a role in controlling activity levels of the MC4R gene, the researchers believe.

"A better understanding of the genes behind diabetes and cardiovascular disease means that we will be in a good position to identify people whose genetic inheritance makes them most susceptible," said Prof Kooner. "We can't change their genetic inheritance. But we can focus on preventative measures."

The findings were published yesterday in the journal Nature Genetics.