Three years ago, geneticists reported the startling discovery that nearly half of all people in the U.S. with European ancestry carry a variant of the fat mass and obesity associated (FTO) gene, which causes them to gain weight from three to seven pounds, on average but worse, puts them at risk for obesity.
Now, UCLA researchers have found that the same gene allele, which is also carried by roughly one-quarter of U.S. Hispanics, 15 percent of African Americans and 15 percent of Asian Americans, may have another deleterious effect.
Reporting in the early online edition of the journal Proceedings of the National Academy of Sciences, senior study author Paul Thompson, a UCLA professor of neurology; lead authors April Ho and Jason Stein, graduate students in Thompson's lab; and colleagues found that the FTO variant is also associated with a loss of brain tissue. This puts more than a third of the U.S. population at risk for a variety of diseases, such as Alzheimer's.
Using magnetic resonance imaging, the researchers generated three-dimensional "maps" of brain volume differences in 206 healthy elderly subjects drawn from 58 sites in the U.S. as part of the Alzheimer's Disease Neuroimaging Initiative, a large, five-year study aimed at better understanding factors that help the brain resist disease as it ages.
They found that there was consistently less tissue in the brains of those who carry the FTO allele, compared with non-carriers. Individuals with the "bad" version of the FTO gene had an average of 8 percent less tissue in the frontal lobes, the "command center" of the brain, and 12 percent less in the occipital lobes, areas in the back of the brain responsible for vision and perception. Further, the brain differences could not be directly attributed to other obesity-related factors such as cholesterol levels, diabetes or high blood pressure.
Thompson called the findings worrying and mysterious.
|Contact: Mark Wheeler|
University of California - Los Angeles