Researchers have discovered that the loss of a key segment of DNA can lead to severe childhood obesity.By looking for CNVs that were unique in children with severe obesity, compared with over 7,000 controls (apparently healthy volunteers), they found that certain parts of the genome were missing in some patients with severe obesity. They found that part of chromosome 16 can be deleted in some families, and that people with this deletion have severe obesity from a young age.
“Our results suggest that one particular gene on chromosome 16 called SH2B1 plays a key role in regulating weight and also in handling blood sugar levels. People with deletions involving this gene had a strong drive to eat and gained weight very easily”, says study leader Dr Sadaf Farooqi.
The findings also have implications for diagnosing severe childhood obesity, which has on occasion been misattributed to abuse. Some of the children in the study had been formally placed on the Social Services ‘at risk’ register on the assumption that the parents were deliberately overfeeding their children and causing their severe obesity. They have now been removed from the register.
“This study shows that severe obesity is a serious medical issue that deserves scientific investigation,” says Dr Farooqi. “It adds to the growing weight of evidence that a wide range of genetic variants can produce a strong drive to eat. We hope that this will alter attitudes and practices amongst those with professional responsibility for the health and well-being of children.”
Obesity is increasing throughout the world and is now recognized as a major global public health concern. Although the increased prevalence of obesity over the past 30 years is undoubtedly driven by environmental factors, genetic factors play a major role in determining why some people are more likely to gain weight than others.
1. Elena G. Bochukova et al, Large, rare chromosomal deletions associated with severe early-onset obesity. Nature, 6 December 2009 doi:10.1038/nature08689.
