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| 22 de agosto de 2002 |
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For Further Information:
Relaciones públicas
617-355-6420
Pager: 617-430-0521
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Identification of risk factor will benefit people of African descent
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A team of investigators from Children's Hospital Boston, the University of Utah, Columbia University, and St. George's Hospital Medical School in London have deciphered how a variant of the cardiac sodium channel gene SCN5A is associated with increased risk of arrhythmia in people of African descent. The research team, led by Mark Keating, MD, senior associate, department of Cardiology, Children's Hospital Boston, professor of Cell Biology at Harvard Medical School and a Howard Hughes Medical Institute investigator, had discovered the Y1102 variant four years ago and since then recruited more than 1,500 study participants to see how the effects of the variant might play out in the general population.
The new findings, reported in the August 23 issue of Science, could benefit African-Americans by making it possible to detect who is at increased risk for developing arrhythmias and allowing those affected to take preventive measures. The study is one of the first in which researchers have been able to discern how genetics influences arrhythmia risk across a range of populations of people who originated from different geographic regions.
Arrhythmia, an abnormal heart rhythm in which the heart beats irregularly, too fast, or too slowly, is most often caused by heart disease or the aging process. Currently, an estimated 4.6 million Americans have arrhythmias and although the condition is often treatable, 450,000 people in the United States die suddenly from it every year.
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The research reported in Science demonstrates how variant Y1102 can affect cardiac sodium channels' behavior. Since the cardiac sodium channel in the cell membrane initiates action potentials, an essential aspect of the molecular electrical system that causes the heart to beat, changes in sodium channel behavior can influence excitability of the heart. The study shows how Y1102 causes the sodium channel to remain in the open rather than the closed configuration more than is normal and how this increases risk of arrhythmia. Keating describes the open configuration as similar to an overly sensitive gas pedal in a car.
Although the variant can increase the risk of arrhythmia, Keating emphasizes that the risk is very low. The investigators see Y1102 as a helpful marker in the setting of other arrhythmia risk factors, such as medications, hypokalemia (an excess of potassium in the blood), or other heart disease. ''I think it is useful information for a person, or the person's physician, when choosing medicines such as diuretics, or for people with heart disease,'' says Keating.
While the results of the study show that the variant is common, that it is found primarily in people of African descent, and that many people carry the variant, the good news is that most carriers need not worry. And for those who are at risk due to other risk factors, the information might help prevent arrhythmia.
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The study is a frontrunner in how research can be conducted in the post-genomic era. ''Before the sequencing of the human genome, genomics tended to focus on the investigation of rare diseases,'' says Keating. ''The true promise of the sequencing of the human genome is that investigators can now look at previously identified 'rare' genes and see how their variants affect the general population.'' Keating credits team members Igor Splawski, a Children's Hospital colleague and the lead author on the Science paper, and Katherine Timothy, a long-standing colleague from the University of Utah, with unwavering perseverance and dedication in enrolling the large number of people needed to complete the study.
Keating's research is supported by the National Heart, Lung, and Blood Institute of the National Institutes of Health and the Howard Hughes Medical Institute.
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Children's Hospital Boston is the nation's premier pediatric medical center. Fundado en 1869 como un hospital para niños con una capacidad de 20 camas, en la actualidad es un centro integral con 300 camas dedicado a la atención médica de niños y adolescentes. Los valores de excelencia en la atención del paciente y la sensibilidad hacia las complejas necesidades y la diversidad de niños y familias son su fundamento. In addition, more than 100 outpatient specialty clinics are located at Children's. Children's Hospital is the primary pediatric teaching affiliate of Harvard Medical School, home to the world's leading pediatric research enterprise, and the largest provider of health care to the children of Massachusetts. For more information about the hospital visit: www.childrenshospital.org.
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