Six new gene mutations linked to obesity
Researchers have identified at least six new gene mutations linked to obesity and said on Sunday they point to ways the brain and nervous system control eating and metabolism.
Joel Hirschhorn at Children’s Hospital and Harvard Medical School in Boston led a team called Genetic Investigation of Anthropometric Traits or GIANT to screen 15 different studies of the entire human genetic map and pinpoint the six new genetic variations.
“Today’s findings are a major step forward in understanding how the human body regulates weight,” Dr. Alan Guttmacher, Acting director of the National Human Genome Research Institute, said in a statement.
“This study essentially doubles in one fell swoop the number of known and replicated genetic factors contributing to obesity as a public health problem,” added Dr. Kari Stefansson, Chief Executive Officer of DeCODE Genetics of Iceland, who led a team that made similar findings in a separate study.
The GIANT team found variations in six genes — TMEM18, KCTD15, GNPDA2, SH2B1, MTCH2 and NEGR1 — were strongly associated with a height-to-weight ratio known as body mass index or BMI.
“One of the most notable aspects of these discoveries is that most of these new risk factors are near genes that regulate processes in the brain,” added Stefansson, whose company hopes to sell genetic tests based on such discoveries.
“This suggests that as we work to develop better means of combating obesity, including using these discoveries as the first step in developing new drugs, we need to focus on the regulation of appetite at least as much as on the metabolic factors of how the body uses and stores energy,” Stefansson said.
“These new variants may point to valuable new drug targets,” he added.
Nearly a third of U.S. adults are considered obese with a BMI of 30 or more. Obesity is associated with more than 100,000 deaths each year in the U.S. population and trends are similar in many other countries.
“We know that environmental factors, such as diet, play a role in obesity, but this research further provides evidence that genetic variation plays a significant role in an individual’s predisposition to obesity,” said the genome institute’s Dr. Eric Green.
Genetic Variants Tied to Obesity
Certain people just may be destined to be obese, based on the discovery of six additional genetic variants tied to people with higher body mass index, a new study says.
The study by an international consortium, published online Dec. 14 in Nature Genetics, adds to previous research that linked two other genetic variants to obesity.
“One of the interesting things is that the genes near these variants are all active in the central nervous system, suggesting that inherited variation in appetite regulation may have something to do with people’s predisposition to obesity,” study leader Dr. Joel Hirschhorn of Children’s Hospital Boston and the Broad Institute of Harvard and MIT, said in a news release issued by some of the consortium participants.
The study, by the Genetic Investigation of Anthropometric Traits (GIANT) consortium, concluded that each individual known variant had a small but cumulative effect on a person’s BMI, a ratio of weight to height. In all, it added up to an average of 10 pounds in those with most of the variants, compared to those with the fewest. However, Hirschhorn said the researchers may have found only a handful of possibly hundreds of genetic regions that made such small contributions to one’s weight, and more studies would be needed to uncover them all.
“As we learn more about what some of the genes in these regions do, we hope that these discoveries might suggest routes to new therapies for obesity,” joint first author of the study, Dr. Elizabeth Speliotes of Massachusetts General Hospital, said in the news release.
Previous studies in families or twins have found that genetics account for up to 70 percent of BMI variation in the general population.
The World Health Association estimates that more than 1 billion adults worldwide are overweight, with at least 300 million of them classified as obese (having a BMI of 30 or above).