Excessive weight gain is elicited by alterations in energy balance, the finely modulated equilibrium between caloric intake and expenditure. But not all lifestyle factors count, as genetics factors also play a role.
The discovery, which appears in the latest edition of the New England Journal of Medicine, links gaps in the BDNF gene to greater likelihood of obesity, at least in children with a rare genetic disorder called the WAGR syndrome.
Researchers from the National Institute of Child Health and Human Development studied 33 children (average age: 11) with WAGR syndrome. Children suffering from this syndrome have a certain type of kidney tumor, no iris in the eye, genitourinary problems, and mental retardation.
Normally a person has two copies of the gene that controls BDNF. But the researchers found that most of the WAGR syndrome patients -- 19 of them -- were missing one copy of the gene, and thus had low blood levels of BDNF.
Every one of the 19 was obese by age 10 and had a strong tendency to overeat. The 14 other people who had two working copies of the gene were no more likely than the general population to be obese or overeat.
Those findings prove that BDNF may help regulate calorie intake, based on studies in animals. However, it does prove that the BDNF gene gaps caused obesity. More studies are needed in people, researchers said.
