Identifying those at high risk for sudden cardiac death before fatalities occur has been challenging, both at the clinical and at the genetic level, says the study's other first author, Arne Pfeufer, M.D., of the Institute of Human Genetics at the Technical University in Munich, Germany. Doctors estimate that in more than one third of all cases, sudden cardiac death is the first hint of heart disease. It is widely believed that many factors, genetic and environmental, contribute to irregular heartbeat and other conditions that may lead to sudden cardiac death. Being able to identify predisposed individuals can save their lives by prescribing beta-blockers and other drugs that regulate heart rhythm, and even by implanting automatic defibrillators in those with the highest risk.
In an effort to identify risk factors with a genetic foundation, the researchers took the unconventional approach of starting from scratch and not looking at genes already known or suspected to be involved in heart rhythm.
"Studying individual genes is not going to open new areas of research," says Chakravarti. "Using a whole-genome approach allows us to find new targets that we never would have imagined."
So instead of focusing on so-called candidate genes with known functions that are highly suspect in heart beat rhythm, the team first focused on people who have extremely long or short QT intervals. The researchers used subjects from two population-based studies, about 1800 American adults of European ancestry from the Framingham Heart Study of Framingham, Mass., and about 6,700 German adults from the KORA-gen study of Augsburg, Germany.
The research team then searched for any specific DNA sequences that
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Source:Johns Hopkins Medical Institutions