In the U.S., childhood obesity has more than tripled in the last 30 years and everyone from the food industry to parents to school lunch providers have been dished their fair share of blame.
While environmental factors can have a profound effect on children’s weight, researchers also know that genes increase susceptibility to weight gain, and in a recent study, scientists found two gene variants that appear to play a large role in predisposing some children to obesity more than others.
“It is clear from our research that there is a genetic signature to childhood obesity. This should motivate us and other researchers to uncover further genetic components to the trait,” says the study’s lead author, Dr. Struan Grant, associate director of the Center for Applied Genomics at the Children’s Hospital of Philadelphia.
Previous research on the genetics of obesity has focused on variants that are associated with extreme obesity in children and adults, but the new study isolates genes involved in common obesity — the kind we normally attribute to sloth and overeating.
Genetic researchers collaborating internationally conducted a meta-analysis of 14 studies looking at childhood genetic data from the United States, Canada, Australia and Europe. Together, the studies involved 5,530 obese kids and 8,318 non-obese kids. It is the most extensive look at genetic influences on childhood obesity.
Grant and his team found two gene variants they believe increase the risk of obesity: one near the OLFM4 gene on chromosome 13, and the other within the HOXB5 gene on chromosome 17. Although the exact function of these genes is unknown, Grant says the biology of the genes “hints at a role of the intestine” and could be related to the function of bacteria that live in the gut.
“Once the picture gets increasingly clear we can start addressing gene-environment interactions,” says Dr. Grant. “Post that, we should be in a position to start tailoring lifestyle and dietary advice to children based on their genetic make-up. These genetic ‘signposts’ give us novel insights in to the biology of childhood obesity, which in turn presents us with new intervention opportunities through the development of more effective therapies.”
The greatest contribution from these findings is the possibility for improved development of pharmacological treatments for overweight kids, says Karen Winer, a program director at the Eunice Kennedy Shriver National Institute of Child Health and Human Development, part of the National Institutes of Health, which helped fund the new study. “Certain kids, even in the best environments, are prone to be obese because of genetics. Actually identifying the genes really helps. Dr. Grant connects the genes to gut physiology, which could help us develop pharmaceutical developments in the future,” she says.
And the need for these developments is growing increasingly dire. “Clearly we don’t have really good treatments for obesity,” says Winer. “We treat it once it has adverse consequences like insulin resistance. But to really treat and prevent obesity in kids and adults — we don’t have that. Some very obese adults undergo surgery, but pharmacological interventions have not been available for these individuals, and there are so many. There’s a huge number of obese kids in the U.S. today that could benefit.”
The new study was published online in the journal Nature Genetics.