May 1, 2004
A growing understanding of how certain diseases take shape might one day help scientists find ways to prevent them.
Researchers are finding that the signs of incipient disease often appear years before any symptoms occur.
"Maybe it's 20 years away, but identifying people before they get sick gives us the opportunity, with further research, to find preventive therapies," said Dr. R. Hal Scofield, a professor of medicine at the University of Oklahoma Health Sciences Center and the author of an article on the subject in the latest issue of the Lancet.
Much of the insight develops from research on autoimmune diseases, in which the body is attacked by some of its own proteins, known as autoantibodies. In a study this year, scientists looked at blood donors who later developed rheumatoid arthritis. About half the patients had autoantibodies for the disease an average of four and a half years before diagnosis. Patients who had the marker, the researchers found, also ended up with a more severe form of the disease than those who did not. A Swedish study of rheumatoid arthritis, published last year, found similar results.
Dr. Scofield, in studies of his own, has found that autoantibodies often foreshadow the onset of lupus, a potentially deadly disease that affects the skin, joints, blood and kidneys. With colleagues at the Oklahoma Health Sciences Center last year, he studied the stored blood of healthy military personnel and compared a group that developed lupus with a group that did not. Of those who did develop the disease, 88 percent had at least one autoantibody about 10 years before diagnosis. Just 3.8 percent of the control group tested positive for the proteins.
"This could put us in a position to interfere with the progression of the disease in a way that leads the patient toward health, rather than illness," said Dr. John B. Harley, chief of rheumatology at Oklahoma Health Sciences and a co-author of that paper, which appeared in October in The New England Journal of Medicine.
In the last few years, scientists have identified antibodies that appear to precede thyroid disease, multiple sclerosis and Addison's disease, a life-threatening condition that impairs the adrenal glands. But some markers are stronger predictors of disease than others. The antibodies associated with thyroid disease, Dr. Scofield pointed out, are common in the general population.
"Many people will have the antibodies for thyroid disease and not go on to get it," he said.
Scientists have made the most progress in finding markers for Type 1 diabetes. Siblings of people with diabetes, studies have found, also have a high risk of developing it if they have two or more of the associated autoantibodies. Researchers are trying to figure out whether therapies like daily nasal insulin affect the onset of Type 1 diabetes in people at the greatest risk.
But screening to determine risk for other autoimmune diseases, Dr. Harley
cautioned, may still be years away. "We may eventually be in a position
to prevent illness in selected circumstances," he said. "But which circumstances
and why are questions that have to be answered by future research."
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