Kids who overeat and under-exercise might have a good excuse, thanks to science — those bad habits could be genetic. In a study published this month in the journal Nature Genetics, researchers identified two genetic variants linked to common child obesity.
"We see a clear genetic signature to childhood obesity, showing that there is more than just an environmental component to this disease," Struan Grant, lead researcher and associate director at The Children's Hospital of Philadelphia, tells HealthDay.
While past research has made a genetic link to cases of extreme obesity, what's new is that genes could be playing a major role in the common cases of obesity, which has mostly been blamed on bad diet and a lack of exercise.
The researchers in this study looked at the results of 14 different genome-wide studies, with a total of 5,530 obese and 8,318 non-obese children, all of European extraction. They found associations with two locations that had not previously been linked to obesity — the OLFM4 gene, appearing on chromosome 13, and the HOXB5 on chromosome 17 — as well as some evidence for the implication of two other genetic variants.
"This is the largest-ever genome-wide study of common childhood obesity," says Grant, "in contrast to previous studies that have focused on more extreme forms of obesity primarily connected with rare disease syndromes."
"As a consequence, we have definitively identified and characterized a genetic predisposition to common childhood obesity."
The new discovery comes at a critical time, with childhood obesity on the rise internationally — including in Canada, where the rates of childhood obesity have almost tripled over the last few decades. These days, over 26 per cent of children between the ages of two and 17 are either overweight or obese.
This research brings us closer to understanding why so many kids are dangerously overweight.
"Once the picture gets increasingly clear we can start addressing gene-environment interactions," Grant tells TIME. "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."
According to Eric Schadt, the chairman of genetics and genomic sciences at Mount Sinai School of Medicine in New York, we're at the very early stages of understanding the genetics of obesity in children.
"This is a disease that has genetic components and very strong environmental components," he tells HealthDay. "It's very, very complicated. We're only scratching the surface of genetic determinations of childhood obesity."