Miércoles 21 de Noviembre de 2007, Ip nº 217

Researchers move closer to understanding obesity gene
Por Alok Jha

Scientists have taken a big step in understanding how a gene linked to obesity works. The discovery will lead to a better understanding of why some people tend to put on weight more easily than others and may offer the potential to develop drugs that could help.

The FTO gene, found in April by a team of British geneticists, is known to influence whether a person becomes obese - but until now no one knew what the gene actually did in the body and, therefore, how it caused obesity.

In the latest study, which looked at FTO in mice, researchers found the gene was involved in repairing DNA and switching the activity of other genes on and off. "We know that FTO is expressed in many tissues in the body, and is found in regions of the brain associated with regulation of appetite," said Frances Ashcroft, a physiologist at Oxford University.

The results of her work, carried out in collaboration with colleagues led by chemist Chris Schofield, are published today in Science.

"This is the first glimpse into the possible mechanisms whereby this very common genetic variant might influence a person's risk of obesity," said Stephen O'Rahilly of Cambridge University, who also took part in the study. "The finding that FTO is an enzyme with these actions on DNA is very surprising and a lot of work is still needed to work out how its actions influence body weight."

In the UK, more than a fifth of adults are obese and of the remaining population half of men and a third of women are classified as overweight. Worldwide, there are an estimated 300 million obese people and obesity is linked to heart disease, diabetes and premature death.

Around half of the UK population carry a variant of FTO and are, on average, 1.6kg heavier than those who do not have it; 16% of the population carry two copies of the gene and are, on average, 3kg heavier. People with the FTO variant also have an increased risk of diabetes.

Prof O'Rahilly added: "The finding that FTO may have some involvement in the control of the function of the hypothalamus suggests that, like other obesity genes previously discovered, it may play some role in the influencing how well the brain senses hunger and fullness. As the activity of FTO can be altered by small molecules like metabolites, it is possible, in the future, that FTO could be manipulated therapeutically to help treat obesity."

Prof Ashcroft said there was still much to do in understanding the genetic influence on obesity. "What we have here [with FTO] is something that is causing obesity in the general population, not a rare mutation in a single gene that causes a dramatic effect on body weight. [Obesity] is a common disease and that means it probably will occur in combination with other genes to make the obesity phenotypes."


  09/11/2007. The Guardian.