Gut bacteria: How genes determine the fit of your jeans

Our genetic makeup influences whether we are fat or thin by shaping which types of microbes thrive in our body, according to a Cornell-led study published today in the journal Cell.

By studying pairs of twins, researchers identified the Christensenellaceae bacterial family, which is highly heritable and more common in lean individuals. Moreover, a member of this class of bacteria, Christensenellaceae minuta, protected against weight gain when transplanted into mice.

The findings pave the way for personalized probiotic therapies that are optimized to reduce the risk of obesity-related diseases based on an individual’s genetic makeup.

“If you look across the population of gut bacteria and explain abundances, there is a host genetic component,” said Ruth Ley, associate professor of microbiology and the paper’s senior author. “Up until now there had been no direct evidence that anything in the human gut is under that kind of genetic influence.”

Genetic data that included 171 identical and 245 fraternal twins, whose genomes have been sequenced at King’s College in London and are stored in its “TwinsUK” registry, gave them the power to answer questions and rank which microbes in the human gut are heritable, Ley said.

With twins raised in the same households, “you can assume that environmental influences are going to be very similar to one another,” said Julia Goodrich, a graduate student and National Science Foundation Graduate Research Fellow in Ley’s lab and the paper’s first author. When Goodrich analyzed the microbe populations in the twins’ fecal samples, she found that identical twins, who have the same genetic makeup, had more similar gut microbiotas to each other than did fraternal twins, who share half the same genes.

Co-authors include Andrew Clark, Cornell professor of population genetics, and Timothy Spector, a professor of epidemiology at King’s College, among others.

The study was funded by the National Institutes of Health, the Cornell Center for Comparative Population Genomics, the Wellcome Trust and the European Community’s Seventh Framework Programme.

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