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Gene study finds “clearest link yet” to obesity

April 12, 2005
Courtesy Wellcome Trust
and World Science staff

U.K. sci­en­tists say they have iden­ti­fied the clear­est ge­net­ic link yet to obes­i­ty in the gen­er­al pop­u­la­tion. Peo­ple with two cop­ies of a par­tic­u­lar gene var­i­ant have a 70 per­cent high­er risk of be­ing obese than those with no cop­ies, the re­search­ers found.
Obes­i­ty is on the rise world­wide and is a ma­jor health prob­lem, being as­so­ci­at­ed with high­er risk of type 2 di­a­be­tes, heart dis­ease and can­cer. 

Sci­en­tists from Pen­in­su­la Med­i­cal School in Ex­e­ter and the Uni­ver­si­ty of Ox­ford iden­ti­fied the ap­par­ent ge­net­ic link through a genome-wide study of 5,000 peo­ple. 

The study was part of the Well­come Trust Case Con­trol Con­sor­ti­um, one of the big­gest pro­jects yet un­der­taken to iden­ti­fy genes that may pre­dis­pose peo­ple to or pro­tect them from ma­jor dis­eases. 

The re­search­ers said they iden­ti­fied a strong as­so­ci­a­tion be­tween an in­crease in obes­i­ty—as meas­ured by an in­di­ca­tor called body mass in­dex—and a var­i­ant, or “al­lele,” of a gene called FTO. The find­ings are pub­lished on­line April 12 in the jour­nal Sci­ence.

Af­ter the in­i­tial find­ings, the re­search­ers tested a fur­ther 37,000 peo­ple from var­i­ous re­gions in the UK and Fin­land. 

Those with one copy of the var­i­ant have a 30 per­cent in­creased risk of be­ing obese com­pared to peo­ple with no cop­ies, they found. And some­one with two cop­ies has a 70 per­cent in­creased risk, be­ing on av­er­age 3 kg (6.6 lb) heav­i­er than a si­m­i­lar per­son with no cop­ies. Among white Eu­ro­peans, about one in six peo­ple car­ry two cop­ies, the sci­en­tists said.

“We are eat­ing more but do­ing less ex­er­cise, and so the av­er­age weight is in­creas­ing, but with­in the pop­u­la­tion some peo­ple seem to put on more weight than oth­ers,” said An­drew Hat­ter­s­ley of Pen­in­su­la Med­i­cal School. “Our find­ings sug­gest a pos­si­ble an­swer to some­one who might ask ‘I eat the same and do as much ex­er­cise as my friend next door, so why am I fat­ter?’ There is clear­ly a com­po­nent to obes­i­ty that is ge­net­ic.” But the re­search­ers said they don’t yet know just how the var­i­ant leads to great­er obes­i­ty.

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U.K. Scientists say they have identified the clearest genetic link yet to obesity in the general population. People with two copies of a particular gene variant have a 70% higher risk of being obese than those with no copies, the researchers found. Obesity, on the rise worldwide, is a major cause of disease, associated with an higher risk of type 2 diabetes, heart disease and cancer. Scientists from Peninsula Medical School in Exeter and the University of Oxford identified the apparent genetic link through a genome-wide study of 5,000 people. The study was part of the Wellcome Trust Case Control Consortium, one of the biggest projects yet undertaken to identify genes that may predispose people to or protect them from major diseases. The researchers said they identified a strong association between an increase in obesity—as measured by an indicator called body mass index—and a variation, or “allele,” of a gene called FTO. The findings are published online April 12 in the journal Science. After the initial findings, the researchers tested a further 37,000 people from various regions in the UK and Finland. Those with one copy of the variant have a 30% increased risk of being obese compared to people with no copies, they found. And someone with two copies has a 70% increased risk, being on average 3 kg (6.6 lb) heavier than a similar person with no copies. Among white Europeans, about one in six people carry two copies, the scientists said. “We are eating more but doing less exercise, and so the average weight is increasing, but within the population some people seem to put on more weight than others,” said Andrew Hattersley of Peninsula Medical School. “Our findings suggest a possible answer to someone who might ask ‘I eat the same and do as much exercise as my friend next door, so why am I fatter?’ There is clearly a component to obesity that is genetic.” But the researchers said they don’t yet know how the variant leads to greater obesity.