Scientists in Cambridge have found that genetic alteration can lead to severe obesity in childhood.
According to a study published in Nature, the loss of a key segment of DNA may play an important role in genetic diseases.
Lead researchers Dr Sadaf Farooqi from the University of Cambridge and Dr Matt Hurles from the Wellcome Trust Sanger Institute examined 300 kids with severe obesity.
Dr Farooqi said: "We 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."
Dr Matt Hurles added: "This is the first evidence that copy number variants have been linked to a metabolic condition such as obesity. They are already known to cause other disorders such as autism and learning difficulties."