Weighty impact of new genetic fat map

13 February 2015

New research has uncovered more than 90 genetic regions that influence obesity, tripling the number of previously known regions. 

Obesity varies between affected individuals; this is due to variation in lifestyle, environmental and genetic factors. Published in Nature, the two new companion papers focus on genetic factors involved in obesity. Genetic differences between individuals are responsible for a large proportion (40% to 70%) of the differences in body mass index (BMI), commonly used to assess obesity, between individuals within populations.

Researchers from the international Giant consortium (Genetic Investigation of Anthropometric Trait) analysed genetic samples from more than 300,000 individuals, constructing the largest ever genetic map of obesity. In the separate studies they uncovered genetic loci associated with BMI, and with waist and hip measurements, both indicators of obesity. Elizabeth Speliotes, co-senior author of the BMI paper said: “the large number of genes make it less likely that one solution to beat obesity will work for everyone and opens the doors to possible ways we could use genetic clues to help defeat obesity”.

Analysing the genetics behind BMI (a ratio of weight and height) Speliotes and her colleagues identified 97 loci of genome wide significance, 56 which had not previously been linked with obesity. Significantly, although some of the regions roles in obesity are yet to be fully understood, they found that some had links with the nervous system. Elizabeth Speliotes said: “…this changes the way we think about obesity – rather than just a metabolic condition, perhaps it has a neurological basis too”.

In the companion paper, the researchers looked at how genetic factors influence where fat is stored, using the observable trait of waist-to-hip circumference. They found 33 new genetic locations linked to body fat distribution and found that 19 of the fat distribution genetic locations had a stronger effect in women, one in men. Karen Mohlke, PhD senior author of the paper said: “We need to know these genetic locations because different fat depots pose different health risks”.

Prof Peter Weissberg, Medical Director at t he British Heart Foundation highlighted the importance of the research identifying genes involved in biochemical pathways that may cause obesity and may link obesity to diabetes and heart disease. 

Talking on the studies senior author Ruth Loos said: "A major challenge now is learning about the function of these genetic variations and how they indeed increase people’s susceptibility to gain weight. This will be the critical next step, which will require input from scientists with a range of expertise, before our new findings can be used towards obesity prevention or treatment strategies”.

For more information on genetic factors and obesity management, see our 2013 report the  Genomics of Obesity.

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