A new study uncovers multiple genetic variations associated with common childhood obesity. The research, published by Cell Press on October 14th in the American Journal of Human Genetics, is likely to guide future studies aimed at characterizing the affected genes and unraveling the complex biology that underlies childhood obesity.

Obesity, which has increased significantly in recent years in Western societies, is a major risk factor for type 2 diabetes and cardiovascular diseases. The majority of obese children become obese adults and adolescent obesity is associated with increased overall mortality in adults. "Despite environmental changes over the last 30 years, in particular the unlimited supply of convenient, highly calorific foods together with a sedentary lifestyle, there is also strong evidence for a genetic component to the risk for obesity," explains senior study author, Dr. Struan F.A. Grant from The Children's Hospital of Philadelphia.

Dr. Grant and colleagues performed a comprehensive genetic analysis of a large group of pediatric subjects of European American and African American descent, some with common obesity and some with a healthy body weight. The researchers were searching for a type of genetic mutation known as a copy number variation (CNV). A CNV is an excess or absence of copies of a particular gene. CNVs have been associated with many inherited human diseases, including extreme obesity. However, most of the studies on obesity focused on adult subjects. "We wanted to complement these earlier studies and address CNVs in common childhood obesity by examining children in the upper 5th percentile of BMI but excluding subjects with the most severe obesity since they often have other serious medical conditions that can be confounding," says co-author Dr. Hakon Hakonarson.

The researchers identified multiple deletion and duplication CNVs that are likely to contribute to genetic susceptibility of common childhood obesity in subjects of European and African ancestry. "Our study represents the first large-scale, unbiased genome wide scan of CNVs in common pediatric obesity and reveals genes impacted by CNVs that are exclusive to cases in two different ethnicities and have not previously been directly implicated in the context of obesity and await further characterization," concludes Dr. Grant. "Further functional studies will be needed to fully characterize the function of the genes at these loci in relation to childhood obesity.