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Personal environment influences effects of genes and risk of disease

March 12, 2016

Indeed, the relative importance of particular SNPs and their interactions were not constant but varied with the genetic background of the yeast strain and the environment.

"Having a particular combination of SNPs was never a great predictor," Cohen says. "If we didn't know the environment in which the yeast were grown, we could not accurately predict the effect of the SNPs on producing spores. And if we can't make accurate predictions about the way environment influences complex traits in yeast, then it will be exceedingly difficult to do so in people."

The new research raises many questions: what is a human's environment and how can it be measured? Is the environment a person lived in during childhood important or the environment he lives in now?

Cohen suspects that any environment that matters is likely to leave a measurable molecular signature. For example, eating a lot of fatty foods raises triglycerides; smoking raises nicotine levels; and eating high-fat, high-sugar foods raises blood sugar levels, which increases the risk of diabetes. The key, he says, is to figure out what are good metabolic readouts of the environment and factor those into statistical models that assess genetic susceptibility to disease or response to medication.

"Measuring the environment becomes crucial when we try to understand how it interacts with genetics," Cohen says. "Having a particular genetic variant may not have much of an effect but combined with a person's environment, it may have a huge effect."

Cohen says he's not hopeless when it comes to personalized medicine. As scientists conduct ever-larger studies to identify rare and common variants underlying diseases such as cancer, diabetes and schizophrenia, they will be more likely to uncover variants that have larger effects on disease. Even then, however, a person's environment will be important, he adds.

SOURCE Washington University School of Medicine