Gene link to obesity

Researchers based in the US have identified a genetic variation that substantially increases a person's risk of obesity. The research team, based at the Boston University Medical School in Massachusetts, found that small genetic changes in a region of DNA near a gene called INSIG2, can increase the likelihood of becoming obese by over 20 per cent. The research is published in the journal Science.

A person's genetic code, contained in their DNA, is made up of four base 'letters' - A, T, C and G. In the DNA near the INSIG2 gene, a single change of one 'letter', from a G to a C, increases the risk of DNA, according to the researchers. Such a change is known as a SNP.The gene plays a role in fat production, and the researchers believe that the nearby DNA code somehow affects the regulation of the gene. They studied almost 87,000 points in the human genome where an SNP variation between individuals is known, and compared these to the body mass index (BMI) of more than 900 people enrolled in a long-running coronary study in Massachusetts, called the Framingham Heart Study. By looking at this they found that the 'C' variation was prevalent in people with obesity.

The researchers, led by Professor Albert Herbert, also found that a person who inherits two 'C' variants of the DNA code is 22 per cent more likely to become obese - according to the commonly accepted definition of the condition, which is having a BMI greater than 30. People with the variation tended to be about one BMI unit heavier than other people.