Personalized medicine centers on being able to predict the risk of disease or response to a drug based on a person's genetic makeup. But a study by scientists at Washington University School of Medicine in St. Louis suggests that, for most common diseases, genes alone only tell part of the story.
That's because the environment interacts with DNA in ways that are difficult to predict, even in simple organisms like single-celled yeast, their research shows.
"The effects of a person's genes and, therefore, their risk of disease are greatly influenced by their environment," says senior author Barak Cohen, PhD, a geneticist at Washington University School of Medicine. "So, if personalized medicine is going to work, we need to find a way to measure a human's environment."
The research is available online in PLoS Genetics.
To understand gene-environment interactions at the most basic level at the individual DNA letters that make up the genetic code the researchers turned to a model organism, the yeast Saccharomyces cerevisiae, culled from North American oak trees and vineyards, where it grows naturally. They asked whether growing the yeast in different environments would influence the rate at which the yeast produce spores, a form of sexual reproduction.
This complex trait is heavily influenced by genetics, Cohen's earlier research has shown. In a study published in 2009 in Science, he determined that just four DNA variants, called single nucleotide polymorphisms (SNPs), account for 90 percent of the efficiency with which yeast produce spores.
In that study, the researchers noted that yeast from oak trees produced spores with 99 percent efficiency; the vineyard strains were far less efficient, at 7 percent. Then, they put each combination of the four SNPs in both the oak and vineyard strains, to determine how the genetic variants interacted with one another.
The researchers showed that the fou
|Contact: Caroline Arbanas|
Washington University School of Medicine