Gene found to influence waist circumference, obesity

June 26, 2009
People who are overweight or obese sometimes joke about their bodies, saying that the waist size of their “jeans” is influenced by the “genes” they inherited from their parents. New research from the University of North Carolina at Chapel Hill, however, suggests that this play on words has some basis in reality.

A consortium of scientists from around the world has found that genetic material passed from parents to child do indeed influence not only an individual’s waist circumference, but also their body mass index (BMI) and level of overall body fat, too.

Dr. Kari North

Dr. Kari North

“Because central abdominal fat has been shown to be a strong risk factor for diabetes and cardiovascular disease – a major health concern around the world – we looked for genes that might predispose people to a larger waist circumference,” said Kari North, PhD, associate professor of epidemiology at UNC’s Gillings School of Global Public Health and a senior author of the study. Keri Monda, PhD, a postdoctoral fellow working with North, was also one of the first authors of the paper.

“Central fat may be more strongly associated with the development of cardiovascular disease as compared with BMI,” said North, who is also a member of the Carolina Center for Genome Sciences. “Finding genetic associations with waist circumference may help scientists better understand why some people may be more susceptible to obesity and cardiovascular disease.”

The study, published June 25 in the journal PLOS Genetics, identified three genetic locations that influence waist circumference. Two of the locations, called MC4R and FTO, previously had been associated with waist circumference, but a new location in the neurexin 3 gene (NRXN3) also was discovered.

North and her colleagues studied the data from more than 70,000 participants, using a two-stage process. The first analysis of more than 31,373 participants confirmed the influence of MC4R and FTO and identified the location in the NRXN3 gene. The second meta-analysis added another 38,641 participants and confirmed the association of NRXN3 with waist circumference.

“But what’s more exciting is that the neurexin 3 gene has previously been associated with substance abuse and other addictive behaviors,” North said. “This suggests a hypothalamic or neurological connection; our genes may influence our desire and consumption of food, and in turn, our susceptibility to obesity.”

The study also found that the neurexin 3 gene influenced BMI and overall obesity, too. “This is not surprising because of the strong correlation between waist circumference and overall body fat,” North said.

 

The study is available at www.plosgenetics.org.

Note: North can be reached at (919) 966-2148 or kari_north@unc.edu.

Gillings School of Global Public Health contact: Ramona DuBose, director of communications, (919) 966-7467, ramona_dubose@unc.edu.