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THURSDAY, April 24 (HealthDay News) -- High levels of C-reactive protein, an inflammatory marker that may warn of impending heart disease, are tied to variations in genes that control metabolism, two new studies show.
The studies identify "new genes that are of potential importance for either the treatment of cardiovascular disease or potentially screening individuals who may be at higher risk of developing cardiovascular disease," said Dr. Alexander Reiner, of the University of Washington, Seattle, who authored one of the reports.
Still unresolved, however, is the exact nature of the relationship between C-reactive protein (CRP) levels and cardiovascular disease.
"That's an absolutely crucial piece of evidence that we don't have, and until we have it, we cannot know whether any of these new [genetic variants] will predict disease," said Dr. James Scott of Imperial College London, who was not involved in either study.
The reports are published in the May issue of The American Journal of Human Genetics.
Researchers have known for some time that blood CRP levels can predict one's risk of heart disease and stroke. Like the swelling that occurs when someone cuts a finger, cardiovascular disease is, to a large extent, an inflammatory condition. CRP is an indicator of that inflammation. Not surprisingly, environmental risk factors such as smoking, diet and exercise strongly influence CRP levels. But genetics also play a role -- accounting for about 40 percent elevated CRP levels, Reiner said.
"The genetic side of this is rather straightforward," explained Dr. Paul Ridker of Harvard Medical School and Brigham and Women's Hospital in Boston, who led the second study. "If we know people with high CRP levels are at risk, what governs CRP levels? There's a high environmental risk -- people who don't exercise, who smoke, who are overweight, tend to have higher CRP levels than thin, athletic people. But some thin, athletic people have high CRP levels anyway."
Some genetic factors (including variants in the CRP gene itself) had already been identified. But they accounted for only a small percentage of the variance in these levels; researchers wanted to find the other players. In separate efforts, Reiner and Ridker led research teams to see if they could locate them.
