The study also found that FTO was highly expressed in a region of the brain, called the hypothalamus, which has important roles in the control of hunger and satiety and that, in certain parts of the hypothalamus, the levels of FTO were influenced by feeding and fasting.
"This is the first glimpse into the possible mechanisms whereby this very common genetic variant might influence a person's risk of obesity. 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," O'Rahilly said.
"The finding that FTO may have some involvement in the control of the function of the hypothalamus suggest 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," he said.
Sara Hiom, director of health information at Cancer Research UK, said that the finding was an important piece of research. "This is an important piece of research. We know that obesity increases people's risk of developing a range of cancers as well as other diseases, and the increasing number of people who are overweight will have significant implications for cancer in the future," Hiom said.
Unravelling how this gene works is very exciting and may one day lead to new treatments for obesity. However maintaining a healthy body weight through a balanced diet and regular physical activity is important for general health as well as reducing the risk of many cancers," Hiom added.
The study is issued online in Science Express.