Study Examining Role of Genetics and Environment in Type 1 Diabetes
News Mar 02, 2009
A $10 million, five-year grant renewal from the National Institutes of Health will enable the additional enrollment as well as ongoing monitoring of participants from the two states in The Environmental Determinants of Diabetes in the Young, or TEDDY, study, says Dr. Jin-Xiong She, director of the Medical College of Georgia Center for Biotechnology and Genomic Medicine and TEDDY principal investigator.
Nearly 66,000 newborns from Georgia and Florida already have been screened and 700 enrolled in the international effort that also includes research sites in Colorado and Washington as well as Finland, Sweden and Germany. Worldwide about 360,000 newborns will be screened and 7,800 enrolled.
Newborns are first screened for two of the highest-risk genes for type 1 diabetes, HLA-DR and HLA-DQ, and those enrolled are followed for 15 years, through the peak ages of development of the disease in which the immune system attacks insulin-producing cells of the pancreas.
Children have their blood examined for the earliest sign of attack at multiple visits with study coordinators each year. Parents also keep detailed records of what their children eat, when they get sick or vaccinated and bring in water samples, fingernail clippings and stool samples as part of the effort to piece together the genetic and environmental causes of type 1.
"You really have to look at the progression of the disease longitudinally," says Dr. She, Georgia Research Alliance Eminent Scholar in Genomic Medicine. "Without the dedication of the participating families, we could not do this. It's a huge commitment. They are trying to do everything they can to help us find a cure for diabetes."
One in 200 children in the U.S. develop type 1 diabetes, an incidence rate that is increasing 3 to 5 percent each year, researchers say. Although TEDDY screens for just two, about a dozen genes are now known to increase risk. Drs. She and Cong-Yi Wang discovered one of those genes, SUMO-4, in 2004 and will soon publish findings about another. When more comprehensive genetic screening is available - Dr. She thinks there are at least 20 genes - it should be about 50 percent accurate at identifying children who will develop the disease, he says.
Dr. She's studies are yielding protein markers that indicate there are actually subtypes of type 1 diabetes, which fits with the large number of genes and apparent environmental factors that seem to come into play. "You are probably not going to stop the disease in all children with one approach." Rather he hopes TEDDY will help researchers identify child-specific causes so an individualized treatment or even prevention strategy can be identified.
"We want to identify the environmental factors, we can't do anything yet about the genetic factors," says Diane Hopkins, project manager. "We think high-risk children are exposed to a set of triggers, it may be dietary, it may be viral, it may be a stressor, it may be all three. It could be viral but only if the exposure occurs early in life. It may be different things in different people. It's anybody's guess at this point."
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