Obesity is influenced environmental and genetic factors. The genetic predisposition accounts for more than 50 percent of the variance in body weight. Roughly three dozen genes are known to have an influence on body weight regulation. Together with international colleagues, a group of scientists of the University of Duisburg-Essen (UDE) has identified two new genetic loci for obesity. The results are part of a large international study.
Initially, the scientists analyzed early-onset obesity. Genetic data of 5,530 obese children and adolescents and 8,318 normal weight controls from 14 national studies - including study groups from Essen - were used. "Subsequently it turned out that the identified genes also cause weight gain in adults" explained Dr Anke Hinney. The molecular geneticist from the Department of Child and Adolescent Psychiatry, University of Duisburg-Essen is looking for genetic predispositions for obesity together with Prof Dr Johannes Hebebrand (Head of the Department) and Dr André Scherag of the Institute for Medical Informatics, Biometry and Epidemiology, University of Duisburg-Essen.
The newly identified variants have cumbersome names: One ('rs9568856') is located in the proximity of a gene called OLFM4, the other 'rs9299', is located near a gene called HOXB5. Their existence is far from being disadvantageous. Nature has been clever, says Anke Hinney, "The discovered genetic variants confer a clear advantage for survival during times of scarcity, because sparsely available calories can be used optimally." Environmental conditions are also relevant. "One only gains a considerable amount of weight if further genetic variants are involved, as well as other factors like intake of highly caloric food and lack of exercise" demonstrates Dr André Scherag.
What benefit do obese people have from the fact that more and more genetic variants are being discovered? "We are hope to be able to improve therapy for overweight individuals by shedding light on underlying biological mechanisms", claims Prof Dr Hebebrand who is also the coordinator of the obesity network that is funded by the Federal Ministry of Education and Research (BMBF).
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