Obesity is a growing problem in the United States, and this map from 2007 shows the percentage increase in cases of obesity by state in the US between 1987 and 2007. Identifying the causes of obesity, both environmental and genetic, is important to reduce obesity-related health risks. [Credits: edkohler (flickr), under the Creative Commons license.]

Understanding the genetic contribution to obesity has been difficult. Your DNA contains billions of positions that together specify the instructions your body follows, such as when to burn more energy, when to store energy as fat, and the size of your appetite. Recent attempts to understand what regions of DNA encode instructions about fat storage and appetite control have pointed to one region, the FTO region, as being strongly associated with obesity. Amongst individuals, small DNA differences, called variants, at the FTO region can affect whether one person is more likely to gain fat than another.

Previous studies have arrived at conflicting results about what the FTO region actually does. A recent news report discusses a scientific study that may have uncovered the function of this region. According to the report, the study pinpoints this region as a regulator of a “switch,” which modifies the activity of genes that determine whether fat is burned for energy or stored in fat cells. Some people with a particular variant at the FTO region have the “switch” left on, which increases fat storage and fat cell size, and decreases energy burning activity. The report goes on to suggest that gene therapy could be used to turn off this “switch” in obese people to help them lose pounds.

The potential for gene therapy to help obese people significantly lose weight must be interpreted carefully, however. One reason is that changing a single variant may only have a tiny effect. As the news report hints, understanding the circuit that the switch is a part of will be crucial to being able to control fat storage more completely.

Managing correspondent: Emily Low

Acknowledgments: Special thanks to Michael Guo, a Ph.D. student in the Biological and Biomedical Sciences program at Harvard Medical School, for expertise in human genetics and FTO studies.

News report: ScienceMag

Research article: The New England Journal of Medicine

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