Scientists Spot Genes Behind Heart Disease

But doctor's office-based DNA tests are still a long way off, experts say

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WEDNESDAY, July 18, 2007 (HealthDay News) -- A number of common genes can boost carriers' risk of heart trouble, an international team of researchers report.

"We found that there are several common gene variants, occurring at frequencies of 20 to 50 percent in the population, each of which increases your risk of having coronary artery disease or heart attack by between 20 and 40 percent," said lead researcher Dr. Nilesh Samani, a professor of genetics at the Institute of Genetics at University of Leicester, in the United Kingdom.

It has been known for a long time that a family history of heart disease is one of the most potent risk factors for someone developing the disease themselves, Samani noted.

Now, he said, "we have identified some of the individual components of this genetic risk. All the genes we have identified have not previously been recognized as being involved in causing heart attacks."

Specifically, the researchers found several new genetic variations that increase the risk of developing heart disease by as much as 40 percent. "Particularly, variants in our DNA on chromosomes 2, 6, 9, 10 and 15, and two on chromosome 1, were associated with increased risk of developing coronary artery disease and heart attacks," said co-researcher Dr. Heribert Schunkert, from the University of Lubeck, Germany.

The study is one of the largest efforts to screen the entire genome, since it combines two independent samples from many thousands of patients (and even more healthy controls) in order to identify minute differences spurring heart disease, Schunkert said.

Still, studies in an even wider set of people are needed before these findings can be applied in a clinical setting, Samani said. However, gene tests might ultimately play a role in predicting the risk of heart disease.

"This, in turn, could allow us to target preventative measures more specifically to those at highest risk," Samani said. "Working out how they affect risk may open up fresh biochemical targets to develop effective drugs against," he said.

The report is published in the July 18 online edition of the New England Journal of Medicine.

One expert believes much more needs to be done to understand which gene does what when it comes to heart disease.

"These genes are just markers for heart disease -- we have no idea what they do functionally," noted Peter Kraft, an assistant professor of epidemiology at the Harvard School of Public Health and co-author of an accompanying journal perspective article.

This is just a first step in understanding how genes affect heart disease, Kraft said. In addition, there are probably other, as yet unidentified, genes that also play a role in heart disease, he said.

Kraft cautioned that the findings should not be taken to mean that genes are destiny and that heart trouble is inevitable for certain people. "That's not the message to take home," he said. "The increase in risk is small on an individual level," he said.

Moreover, the risk for heart disease is more responsive to other factors, such as smoking and obesity, Kraft said.

These findings will lead to a better understanding of the biological causes of heart disease, Kraft said. "These studies offer the opportunity for startling new discoveries," he added.

Another expert agreed that the findings are a long way from being used by doctors to screen for heart disease or even in the development of heart drugs.

The study is part of ongoing research to identify genes associated with common diseases, and it will be five to 10 years before these discoveries will have any practical impact on treating heart disease, said Anne M. Bowcock, a professor of genetics at Washington University School of Medicine in St. Louis.

"These are relatively low-risk effects," she said. "How much of the disease they contribute to is not clear right now."

More information

For more on genes and disease, visit the U.S. National Center for Biotechnology Information.

SOURCES: Nilesh Samani, M.D., professor, genetics, Institute of Genetics, University of Leicester, U.K.; Heribert Schunkert, M.D., University of Lubeck, Germany; Peter Kraft, Ph.D., assistant professor, epidemiology, Harvard School of Public Health, Boston; Anne M. Bowcock, Ph.D., professor, genetics, Washington University School of Medicine, St. Louis; July 18, 2007, online edition, New England Journal of Medicine

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