Another gene variant that's linked to obesity

Geneticists have estimated that a person inherits 30 percent to 70 percent of a tendency to be fat or thin (or body mass index) from his or her parents. At least 70 different mutations or variants of 10 different genes have been implicated in obesity thus far, but just how common the mutations are in people or groups of people is not always clear. A new study which used a pioneering statistical technique to test more than 86,000 DNA sequence variations has identified yet another gene variant that's linked to BMI, an obesity index based on the ratio of weight to height.

And after studying the DNA samples from five different study groups, the researchers calculated that the obesity-predisposing genotype is present in about 10 percent of populations around the world.

Such widespread distribution suggests that the variant has been common in humans for a long time. And, like other gene mutations related to fat storage and eating habits, it probably gave a competitive advantage to early humans who lived with the uncertain food supplies associated with hunting and gathering, only becoming a liability with the abundant food supplies of modern times.

The study, published Friday in the journal Science, started with blood samples taken from nearly 700 participants in the landmark Framingham Heart Study, which has tracked heart disease through three generations of residents of the Massachusetts town since 1948.

Using a technique developed by the Harvard School of Public Health that estimated the extent that genetics can explain variations in a specific trait, the researchers found a single candidate. The variant lies near an insulin-induced gene (INSIG2) that's known to produce a protein that controls the burn rate of fatty acid and cholesterol.

With the new obesity culprit in hand, the researchers joined with scientists at other institutions to determine if the variant could also be linked to an increased risk of obesity in other groups. Those studies confirmed the same association in four of five independent groups, including those of Western European ancestry, blacks and children, and which included both families and unrelated subjects. The analysis also confirmed that people had to have inherited two copies of the mutation to face the increased risk of obesity.

Steve - as more genetic research becomes available, such as this recent one, it reaffirms what we have said for years...while our genes have changed little in the last 10,000 years, our diet has changed completely. Incompatible foods, an overabundant food supply, and latent activity levels create gene expression that leads to obesity. What is so exciting is that obesity gene expression can be "swtiched off" by making the correct lifestyle changes. That is where we come in!