Featured Research

from universities, journals, and other organizations

New associations between diabetes, environmental factors found by novel analytic technique

Date:
May 21, 2010
Source:
Stanford University Medical Center
Summary:
Got diabetes? If so, you probably know that the adult-onset form of the disease can be triggered by, among other things, obesity and a fatty diet. You're also more likely to develop diabetes if other family members have it. But a new study suggests that you should also begin looking suspiciously at other aspects of your life -- like your past exposure to certain pesticides or chemicals and even one form of vitamin E.

Got diabetes? If so, you probably know that the adult-onset form of the disease can be triggered by, among other things, obesity and a fatty diet. You're also more likely to develop diabetes if other family members have it. But a new study by researchers at the Stanford University School of Medicine suggests that you should also begin looking suspiciously at other aspects of your life -- like your past exposure to certain pesticides or chemicals and even one form of vitamin E.

In fact, the association of some of these so-called "environmental" cues with diabetes surpasses that of the best genetic markers scientists have identified for the disease.

Identifying relationships between a person's environment (such as tobacco exposure) and specific health repercussions (such as cancer) is nothing new. Epidemiological studies of large groups of people have been doing just that for decades. But they are limited in their ability to assess the hundreds or even thousands of variables that comprise the intricate fabric of our everyday lives. (What's your risk of heart disease if you smoke sparingly and eat fatty foods, but are also a marathoner?) They're also not open-ended: The researcher has to begin with presuppositions about possible relationships. (Does folic acid prevent birth defects?)

In this new study, the scientists relied instead on an unconventional approach that treats environmental variables as "genes." That conceptual shift allowed them to use some of the same techniques initially developed to identify the many sections of DNA throughout the genome that might contribute to disease development. Bioinformatics expert Atul Butte, MD, PhD, assistant professor of pediatric cancer biology, compared the data generated by the new approach to the amount and types of information gleaned from a DNA microarray.

"This approach catapults us from being forced to ask very simple, directed questions about environment and disease into a new realm in which we can look at many, many variables simultaneously and without bias," said Butte, who is also director of the Center for Pediatric Bioinformatics at Lucile Packard Children's Hospital. "In the future, we'll be able to analyze the effect of genes and environment together, to find, perhaps, that a specific gene increases the risk of a disease only if the person is also drinking polluted well water."

Specifically, in this study, Butte and his coworkers used the technique to identify a previously known association between people with type-2 diabetes and a class of organic compounds called polychlorinated biphenyls, or PCBs, commonly used for many applications until the late 1970s. They also uncovered a strong, but unexpected, relationship between diabetes and high levels of a form of vitamin E called gamma-tocopherol, which is prevalent in fruits, vegetables, nuts and milk.

The scientists are careful to caution, however, that an association doesn't necessarily mean that vitamin E or pollutants cause type-2 diabetes, and that more research is needed to fully understand these complex relationships.

Butte is a senior author of the research, which will be published May 20 in the online journal PLoS ONE. The genetic studies on which the research is based are called "genome wide association studies" or GWAS. In a nod to its origin, the scientists coined the term "environment wide association studies," or EWAS, for the new technique. They expect that EWAS will be useful in the analysis of many complex diseases.

"We've known for decades that environmental factors play a major role in diseases like diabetes, cancer and heart disease," said Jeremy Berg, PhD, director of the National Institute of General Medical Sciences, which partially supported the work. "By enabling us to measure the impact of these factors, this new approach will shed light on how genes and the environment influence our health and could provide insights into new ways to control some of our nation's most serious health problems."

Graduate student Chirag Patel conceived of, designed and executed the computer software for the EWAS. He, Butte and associate professor of medicine Jayanta Bhattacharya, MD, PhD, used existing population studies conducted from 1999 to 2006 by the U.S. Centers for Disease Control and Prevention as part of the National Health and Nutrition Examination Survey. The researchers realized that the databases contained a goldmine of information, including the levels of pollutants and vitamins in subjects' blood and urine as well as clinical measurements such as fasting blood sugar levels.

In all, the scientists analyzed the relationship of 266 unique environmental variables to the likelihood that a person's fasting blood sugar level was 126 milligrams or higher per deciliter (between 70 and 110 mg/dL is considered normal). Higher-than-normal blood sugar levels after an overnight fast are a telltale sign of diabetes. They adjusted for the subjects' age, gender, body mass index, socioeconomic status and ethnicity. Finally, they grouped related variables into 21 classes -- such as dioxins, polychlorinated biphenyls, phthalates, etc. -- similar to how individual genes are assigned to chromosomal units in GWAS.

Butte and his colleagues found that people with relatively higher levels of the pesticide-derivative heptachlor epoxide (a chemical whose use stopped in the '80s but is still prevalent in food, soil and water) in their blood were more likely than those with lower levels to also have high fasting blood sugar levels (odds ratio = 1.7). The same was true for those with high levels of PCBs (OR = 2.2) and the gamma-tocopherol form of vitamin E (OR = 1.5). In contrast, high beta-carotene levels were slightly protective (OR = 0.6).

Scientists have recently made large strides in measuring genetic associations to complex disease, but are still far from using genes to predict risk for complex chronic diseases or even plan preventive measures. On the other hand, our environmental profile is potentially more modifiable and also may provide a more complete model of disease risk when combined with genetic information.

"Studying relationships between a person's environment and their disease burden in this manner is going to be far more impactful," said Butte. "We can now imagine what it might be to look at everything in the environment, in the same way that we've been doing with the genome for the past decade. Imagine one day wearing a chip on your clothing that assesses your exposure to hundreds or thousands of environmental toxins. You could bring that in to your annual physical and you and your doctor could incorporate the information into discussions about disease risk and prevention."

The researchers are planning to conduct similar EWAS studies focused on other diseases, including cancers. They'll also try to reproduce the data from the National Health and Nutrition Examination Survey studies on specific populations in California.

In addition to NIGMS, the research was funded by the National Library of Medicine, the National Institute on Aging, the Lucile Packard Foundation for Children's Health and the Howard Hughes Medical Institute.


Story Source:

The above story is based on materials provided by Stanford University Medical Center. The original article was written by Krista Conger. Note: Materials may be edited for content and length.


Journal Reference:

  1. Chirag J. Patel, Jayanta Bhattacharya, Atul J. Butte. An Environment-Wide Association Study (EWAS) on Type 2 Diabetes Mellitus. PLoS ONE, 2010; 5 (5): e10746 DOI: 10.1371/journal.pone.0010746

Cite This Page:

Stanford University Medical Center. "New associations between diabetes, environmental factors found by novel analytic technique." ScienceDaily. ScienceDaily, 21 May 2010. <www.sciencedaily.com/releases/2010/05/100520212615.htm>.
Stanford University Medical Center. (2010, May 21). New associations between diabetes, environmental factors found by novel analytic technique. ScienceDaily. Retrieved July 31, 2014 from www.sciencedaily.com/releases/2010/05/100520212615.htm
Stanford University Medical Center. "New associations between diabetes, environmental factors found by novel analytic technique." ScienceDaily. www.sciencedaily.com/releases/2010/05/100520212615.htm (accessed July 31, 2014).

Share This




More Health & Medicine News

Thursday, July 31, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Dangerous Bacteria Kills One in Florida

Dangerous Bacteria Kills One in Florida

AP (July 31, 2014) Sarasota County, Florida health officials have issued a warning against eating raw oysters and exposing open wounds to coastal and inland waters after a dangerous bacteria killed one person and made another sick. (July 31) Video provided by AP
Powered by NewsLook.com
Health Insurers' Profits Slide

Health Insurers' Profits Slide

Reuters - Business Video Online (July 30, 2014) Obamacare-related costs were said to be behind the profit plunge at Wellpoint and Humana, but Wellpoint sees the new exchanges boosting its earnings for the full year. Fred Katayama reports. Video provided by Reuters
Powered by NewsLook.com
Peace Corps Pulls Workers From W. Africa Over Ebola Fears

Peace Corps Pulls Workers From W. Africa Over Ebola Fears

Newsy (July 30, 2014) The Peace Corps is one of several U.S.-based organizations to pull workers out of West Africa because of the Ebola outbreak. Video provided by Newsy
Powered by NewsLook.com
Weather Kills 2K A Year, But Storms Aren't The Main Offender

Weather Kills 2K A Year, But Storms Aren't The Main Offender

Newsy (July 30, 2014) Health officials say 2,000 deaths occur each year in the U.S. due to weather, but it's excessive heat and cold that claim the most lives. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

    Environment News

    Technology News



      Save/Print:
      Share:

      Free Subscriptions


      Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

      Get Social & Mobile


      Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

      Have Feedback?


      Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
      Mobile: iPhone Android Web
      Follow: Facebook Twitter Google+
      Subscribe: RSS Feeds Email Newsletters
      Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins