Web Exclusives: Genetics
Scanning the Environment for Disease Risks
Atul Butte is an innovator who takes his inspiration from well-established approaches and huge sets of data available on the Internet. Most recently, he developed a method for understanding what makes us susceptible to diseases.
His new technique is based on an existing one called Genome-Wide Association Studies (GWAS). GWAS compares the DNA of individuals to identify associations between differences in genes. Common genetic variations, for instance, may be associated with the development of a disease.
When it comes to diseases, though, we know that genes tell only part of the story. Until now, biomedical scientists have lacked standard tools to determine the comprehensive role of environmental forces in the same comprehensive way they can study DNA.
"The reality is that probably most of the risk that we have for most common disorders is from the environment," says Butte, a medical bioinformatician and pediatrician at Stanford University. "If we inspire anyone to think of the environment like the genome, we've done a world of good," he says.
Like GWAS, the new technique, called Environment-Wide Association Studies (EWAS), considers many different factors at once. In his latest work, Butte and his team examined how 266 environmental factors contribute to type 2 diabetes using health survey data from the U.S. Centers for Disease Control and Prevention. He found that certain nutrients, like the beta-carotene found in foods like carrots, are associated with a decreased risk. But he also found that our exposure to pollutants, such as polychlorinated biphenyls (PCBs) used since the 1970s to make plastics stronger and clearer, and certain pesticides, such as the banned insecticide heptachlor that still persists in fish, meats and breast milk, are associated with an increased risk.
An even more surprising finding, says Butte, is that a common form of vitamin E is also linked to an increased risk of type 2 diabetes. Previous studies suggested that gamma-tocopherol, the most abundant form of vitamin E in the U.S. diet, could be a preventive agent against colon cancer. "Most people think all vitamins are safe," Butte says. "This was a completely new finding, though we still have much to explore in the biology behind this association."
In the future, Butte would like to combine GWAS and EWAS approaches to provide accurate estimates of risk for a range of major health problems, including cardiovascular disease, cancer and metabolic disorders. He says that he hopes his results will convince government agencies and private organizations to collect a broader range of environmental health factors, including traces of heavy metals and oil spills. With this knowledge, he predicts that scientists could someday develop environment chips that, like gene chips, survey for disease risks.