BETHESDA, Md., Thurs., Apr. 26, 2007 – In the most comprehensive look at genetic risk factors for type 2 diabetes to date, a U.S.-Finnish team, working in close collaboration with two other groups, has identified at least four new genetic variants associated with increased risk of diabetes and confirmed existence of another six. The findings of the three groups, published simultaneously today in the online edition of the journal Science, boost to at least 10 the number of genetic variants confidently associated with increased susceptibility to type 2 diabetes – a disease that affects more than 200 million people worldwide."This achievement represents a major milestone in our battle against diabetes. It will accelerate efforts to understand the genetic risk factors for this disease, as well as explore how these genetic factors interact with each other and with lifestyle factors," said National Institutes of Health (NIH) Director Elias A. Zerhouni, M.D. "Such research is opening the door to the era of personalized medicine. Our current one-size-fits-all approach will soon give way to more individualized strategies based on each person’s unique genetic make-up."
"It's been a formidable challenge to identify the complex genetic factors involved in common diseases, such as type 2 diabetes. Now, thanks to the tools and technologies generated by the sequencing of the human genome and subsequent mapping of common human genetic variations, we finally are making significant progress," said NHGRI Director Collins, who led the NIH component of the Human Genome Project.
Type 2 diabetes affects nearly 21 million people in the United States and the incidence of the disease has skyrocketed in the U.S. and many other developed nations over the last 30 years. Diabetes is a major cause of heart disease and stroke, as well as the most common cause in U.S. adults of blindness, kidney failure and amputations not related to trauma.
NIDDK Director Griffin P. Rodgers, M.D., said, "These genetic findings are exciting news for diabetes research. While more work remains to be done, the newly identified genetic variants may point us in the direction of valuable new drug targets for the prevention or treatment of type 2 diabetes."
Previously known as adult onset or non-insulin dependent diabetes (NIDDM), type 2 diabetes usually appears after age 40, often in overweight, sedentary individuals. However, an increasing number of younger people and even children are developing the disease, which is characterized by the resistance of target tissues to respond to insulin and a gradual failure of insulin-secreting cells in the pancreas.
In addition to lifestyle factors like obesity, poor diet and lack of exercise, doctors have long known that heredity plays a significant role in the risk of developing type 2 diabetes. People who have a parent or sibling with type 2 diabetes face a 3.5-times greater risk than people without a family history of the disease. However, researchers have only recently begun to zero in on particular genetic variants that increase or decrease susceptibility to the disease.
To make their discoveries, researchers used a relatively new, comprehensive strategy known as a genome-wide association study. "Genome-wide association studies offer a powerful way to uncover the genetic variations that contribute to diabetes, as well as other common conditions, such as asthma, arthritis, heart disease, cancer and mental illnesses," Dr. Boehnke said. "Once susceptibility genes are identified, researchers then can use this information to develop better approaches to detecting, treating and preventing disease."
To conduct a genome-wide association study, researchers use two groups of participants: a large group of people with the disease being studied and a large group of otherwise similar people without the disease. Utilizing DNA purified from blood or cells, researchers quickly survey each participant's complete set of DNA, or genome, for strategically selected markers of genetic variation.
If certain genetic variations are found more frequently in people with the disease compared to healthy people, the variations are said to be associated with the disease. The associated genetic variations can serve as a strong pointer to the region of the genome where the genetic risk factor resides. However, the first variants detected may not themselves directly influence disease susceptibility, and the actual causative variant may lie nearby. This means researchers often need to take additional steps, such as sequencing every DNA base pair in that particular region of the genome, to identify the exact genetic variant that affects disease risk.
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Contact:
Geoff Spencer
National Human Genome Research Institute, www.genome.gov
(301) 402-0911
spencerg@mail.nih.gov
