A new study has identified several common genetic variants related to a risk factor for sudden cardiac death. The report receiving early online release in the journal Nature Genetics identifies variants in genes, some known and some newly discovered, that influence the QT interval measured on the electrocardiogram (EKG) performed routinely in doctors' offices. These findings could eventually help to prevent sudden cardiac death and arrhythmia by limiting the use of medications that affect QT interval in people with these variants.
The QT interval is the time from the beginning of electrical activation of the heart to the end of electrical relaxation. "It is well established that prolongation of the QT interval in the general population is a potent and heritable risk factor for sudden death," said Christopher Newton-Cheh, MD, MPH, of the Massachusetts General Hospital (MGH) Center for Human Genetic Research and Cardiovascular Research Center (CVRC) and lead author of the Nature Genetics article. "In addition, QT prolongation results from medications leading to drug-induced cardiac arrhythmias and sudden death. This is a cardiotoxic side effect of scores of medications in widespread use and has been a major barrier to the development of novel drugs. From studies of families with congenital long-QT syndrome, we know that rare mutations with strong effects on ion channel function lead to QT prolongation and sudden death. But the common genetic basis for QT prolongation has been very difficult to establish."
To search for QT-associated variants, the investigators formed the QTGEN consortium, assembling more than 13,000 individuals from three studies including the National Heart, Lung and Blood Institute's and Boston University's Framingham Heart Study, the Rotterdam Study and the Cardiovascular Health Study. All individuals had undergone testing of hundreds of thousands of common gene variations called single-nucleotide polymorp
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Massachusetts General Hospital