We all have that annoying skinny friend who seems to be able to eat anything and never put on weight, yet others struggle to keep the pounds off despite calorie counting and healthy eating. Now new research has uncovered evidence suggesting a new potential genetic cause behind some cases of obesity.

"There is this common belief in the field that much of obesity can be traced back to appetite and the appetite control centers that reside in the brain," says Vann Bennett, senior author on this new study and George Barth Geller Professor of Biochemistry at Duke University School of Medicine. "But what if it isn't all in our head?"

The research centered on a gene called ankyrin-B, discovered over 30 years ago and active in all bodily tissue. Mutations in the gene have been linked to a variety of diseases in humans. A few years ago, the scientists were investigating the links between cardiac arrhythmia and ankyrin-B mutations when a student saw that the mice with variants of the target gene were fatter than their companions.

After creating some mice with human variants of the gene the team quickly verified that the genetic mutations did in fact cause the mice to grow fatter. But the puzzle wasn't solved yet, as Bennett points out, "we still didn't know how this gene worked."

The latest research uncovers the key mechanism explaining how altering this particular gene results in weight gain. It was discovered that by altering, or removing completely, ankyrin-B, it fundamentally affected a protein called Glut4, which controls the rate of glucose entering fat cells. When ankyrin-B is altered, glucose floods rapidly into fat cells at a higher rate than normal, resulting in these cells expanding in size.

It is estimated that 1.3 percent of European Americans and 8.4 percent of African Americans possess some kind of mutation in the ankyrin-B gene and this could make them more susceptible to obesity than others. The immediate result of this kind of research could allow doctors to identify patients with a potential propensity for obesity.

"This gene could enable us to identify at-risk individuals who should watch what kind of calories they eat and exercise more in order to keep their body weight under control," says Bennett.

The next stage for the research is to further confirm the findings in large sections of the general population.

The study was published in the journal Proceedings of the National Academy of Sciences of the United States of America.

Source: Duke University

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