Obesity gene gives hope for treatment

By STEVE CONNOR

Scientists have identified the first gene for obesity in the general population in a discovery that could help to revolutionise the treatment of a disorder that affects a growing number of children.

The gene is involved in appetite stimulation and the researchers believe it could form the basis of a test that could identify youngsters who carry a genetic predisposition to putting on weight.

About one in five British children are overweight because of a combination of lack of exercise and high-calorie diets. Some are highly likely to develop clinical obesity, which raises the risk of heart disease, diabetes and cancer.

Scientists believe an accurate test to identify a genetic tendency to become obese will enable doctors to target those children at highest risk so their diet and lifestyle can be changed.

Philippe Froguel, professor of genomic medicine at Imperial College London, said a genetic test to look for an inherited predisposition would become an essential tool in the fight against obesity.

"Obesity is like many diseases. It has a genetic basis with about 50 per cent of the risk of obesity being driven by the genes," Professor Froguel said.

"I think for obesity, it [a test] will be important in children. We need to have some way to test them, to see who of them will be at high risk of obesity or diabetes."

The gene identified by Professor Froguel's team lies on chromosome 10 - one of 23 pairs that constitute the human genome. Called GAD2, the gene works by speeding up the production of a chemical transmitter in the brain, called GABA, which is involved in appetite stimulation.

The researchers believe people who carry a more active form of the GAD2 gene build up a larger than normal quantity of GABA in the brain, which stimulates the appetite to a point where they overeat.

Professor Froguel analysed the genetic makeup of 576 people from obese families and compared their DNA with that taken from 646 people of normal weight. The study is published in the Public Library of Science Biology, an online journal.

He identified variations in the gene that seem to be significantly more common in the obese subjects.

"One in 10 obese people are probably obese because of this gene," Professor Froguel said.

"Genetic factors alone cannot explain the rapid rise in obesity rates, but they may provide clues to preventative and therapeutic approaches that will ease the health burden associated with obesity," he said.

About 20 genes may be involved in causing common obesity - as opposed to a strictly inherited form of the disorder which runs in families and is the result of a wholly genetic imbalance.

- INDEPENDENT