Recent advances in gene therapies have been a boon to those researchers investigating the genetic causes of disease. With global obesity levels reaching epidemic proportions many scientists are now looking to our DNA to try and understand the genetic factors that could be making us fat. A new study led by Imperial College London has uncovered a specific gene that, when subject to recessive mutations, can lead to cases of severe obesity.

The new study focused on the genetic profiles of a community of children living in a specific region in Pakistan. The population has proved valuable to geneticists due to its frequency of consanguinity (inter-family relationships) leading to previous studies suggesting severe obesity in the community has a genetic origin in up to 30 percent of cases.

One particular gene stood out to the researchers. Called adenylate cyclase 3 (ADCY3), the gene codes for a protein known to be related to appetite control and our sense of smell. When mutations appear in the gene, the production of this vital protein is affected, leading to abnormalities in a variety of biological functions.

"Early studies into ADCY3 tested mice that were bred to lack that gene, found that these animals were obese and also lacked the ability to smell, known as anosmia," says Phillippe Froguel from Imperial College. "When we tested our patients, we found that they also had anosmia, again showing a link to mutations in ADCY3."

The research team then cross referenced its results in a worldwide gene research database called GeneMatcher. Soon several other scientists revealed ADCY3 findings associating positive correlations between severe obesity and mutations in the gene.

One intriguing connection came from a team studying Inuit populations in Greenland. Despite this regional population not being known for consanguineous relations, its small size most likely led to a degree of inbreeding that spread mutations in the ADCY3 gene through the community.

Professor Froguel suggests that identifying a key gene such as this will offer scientists new targets for drugs specifically treating obesity. "Obesity is not always gluttony, as is often suggested, and I think we should have a positive outlook considering the new treatments that are becoming possible."

The study was published in the journal Nature Genetics.