An international study has found that a variation in a gene that is active in the central nervous system is linked to higher risk for obesity.
The new study, conducted by Robert Kaplan, Ph.D., associate professor of epidemiology and population health and his U.S. and European colleagues, adds to evidence that genes influence appetite and that the brain plays a key role in obesity.
In the study, the researchers found that people who have inherited the gene variant NRXN3 have a 10-15 percent increased risk of being obese compared with people who do not have the variant.
The researchers examined data from eight studies involving genes and body weight.
These studies included more than 31,000 people of European origin, ages 45 to 76, representing a broad range of dietary habits and health behaviors.
After analyzing more than two million regions of the human genome, the researchers found that the NRXN3 gene variant - previously associated with alcohol dependence, cocaine addiction, and illegal substance abuse - also predicts the tendency to become obese.
Altogether, researchers found the gene variant in 20 percent of the people studied.
NRXN3 is the third obesity-associated gene to be identified. Dr. Kaplan says that the fact that all three genes are highly active in encoding brain proteins is significant.
"Considering how many factors are involved in obesity, it is interesting that research is increasingly pointing to the brain as being very important in its development," he said.
According to researchers, identifying obesity genes could help in preventing the condition and lead to treatments for it.
"Someday we may be able to incorporate several obesity genes into a genetic test to identify people at risk of becoming obese and alert them to the need to watch their diet and to exercise. Also, we may eventually see drugs that target the molecular pathways through which obesity genes exert their influence," Dr. Kaplan said.
The study has been published online in PLoS Genetics.