New study overturns genes link to obesity

24 June 2015

As data is published suggesting that more than two-thirds of Americans are either overweight or obese, new research confirms a gene previously linked to obesity is unrelated.

The study rules out a link between AMYI gene and obesity, overturning an (until now) common belief about the genetics of obesity. AMYI gene encodes an enzyme that helps humans convert starch into sugar. The gene resides in a structurally complex, poorly understood region of the human genome. 

Co-senior author Joel Hirschhorn, the Concordia Professor of Pediatrics at Boston Children's Hospital and professor of genetics at Harvard Medical School, had previously questioned the influence of AMYI on body mass, following an analysis of genome -wide association data. Teaming up with researchers from the Harvard Medical School, led by Steven McCarroll, they used their combined expertise and confirmed Hirschhorn’s suspicions.

"We have expertise in obesity genetics, and Steve's group has expertise in this kind of complex variation," said Hirschhorn.

The study also provides the first effective ways to anal yse complex parts of the human genome. Co-senior author McCarroll of Harvard Medical School said: "There are hundreds of loci in the human genome with this kind of complexity. They have been like black holes in our knowledge of the human genome…I think this is the beginning of a playbook for making sense of those regions."

Research, published only recently in 2014 by an unrelated international group, reported in Nature Genetics that AMYI had a substantial link to obesity. 

But molecular and mathematic strategies developed through McCarroll and Hirschorn’s research allowed them to examine AMYI’s biological significance with greater accuracy than had previously been possible. They found nine common forms of AMYI, and that most people had some combination of two of them. Running their analysis on the genomes of about 4500 Europeans with a range of body mass indexes they confirmed the suspicions of AMYI having no association with high or low BMI.

The scientists hope that as tools like theirs become available, it will make questions as to the link between a specific gene and obesity easier to answer. Furthermore, the early ruling out of an association of a gene with a disease could save valuable resources that would otherwise have been spent on follow up work.

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