Scientists supported by the National Heart, Lung, and Blood Institute have identified a gene variant that is associated with arrhythmia - abnormal heart rhythm - in African Americans. Mark Keating, M.D., of Children's Hospital, Departments of Pediatrics and Cell Biology, Harvard Medical School, and colleagues report in the August 23 issue of Science that a variant of the cardiac sodium channel gene SCN5A produces a small increase in risk of arrhythmia. When the variant is combined with other factors such as certain medications, low blood potassium known as hypokalemia, or structural heart disease, the risk of life-threatening arrhythmias is increased, according to the researchers.
Keating, a Howard Hughes Medical Institute investigator, and study co-authors conclude that the gene variant, when combined with other risk factors, may one day be a useful marker for the prediction of arrhythmia. At present, there is no test generally available to identify this gene variant, which is present in an estimated 4.6 million African Americans.