Last Updated: 2008-12-15 16:52:48 -0400 (Reuters Health)
WASHINGTON (Reuters) - At least six new gene mutations linked to obesity that point to ways the brain and nervous system control eating and metabolism have been identified, researchers reported Sunday.
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 the height-to-weight ratio known as body mass index (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 one third of U.S. adults are considered obese, with a BMI of 30 or higher. 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.
Dr. Sears comments:
There is strong predisposition toward developing obesity, but this can be highly modulated by the diet. A pro-inflammatory diet will dramatically increase the likelihood of those obesity genes being activated.