It really is genetic
13 Oct 2010 by Evoluted New Media
“It’s genetic” – but overweight people might be telling the truth say scientists who discovered genes associated with overall obesity and fat distribution.
“It’s genetic” – but overweight people might be telling the truth say scientists who discovered genes associated with overall obesity and fat distribution.
|
Scientists discover genes linked to fat distribution and obesity |
In the largest genetic investigation of human traits to date, scientists analysed data from a quarter of a million participants and found 18 new genes associated with obesity and 13 that affect fat distribution.
“Different people have different susceptibilities to obesity,” said Joel Hirschhorn, associate professor of Genetics, “Some don’t rigorously watch what they eat or how much they exercise and still resist gaining weight, while others constantly struggle to keep their weight from skyrocketing. Some of this variability is genetic, and our goal was to increase understanding of why different people have different inherited susceptibility to obesity.”
The obesity study looked for genetic determinants of body mass index (BMI) and identified a total of 32 sites consistently associated with BMI – 18 of which are new. One novel variant encodes for a receptor protein that influences insulin levels and metabolism, while another is near a gene known to encode proteins affecting appetite.
“One of the most exciting parts of this work is that most of the BMI-associated variants identified are in or near genes that have never before been connected to obesity,” said Elizabeth K Speliotes, “Through this work we are discovering that underlying biological underpinnings of obesity are many, varied and largely uncharacterised.”
Individuals who carried more than 38 BMI-increasing variants were on average 15-20lbs heavier than those who carried fewer than 22 variants.
The second study analysed genetic associations with how fat is distributed in the body. Fat stored in the abdomen increases the risk of type 2 diabetes and heart disease, but fat stored in the hips and thighs may actually protect against such diseases. Scientists examined the genetic determinants of waist-to-hip ratios – a measure of fat distribution – and found 14 gene regions associated with waist-to-hip ratio, confirming one previously known association.
Both studies show that although there are genetic variations that contribute to obesity and fat distribution they only explain a small fraction of the variation in body weight and fat distribution – many other genetic and environmental factors also play a part.
