Common Genetic Variation in Blacks Provides Protection From Heart Failure Death, Study Finds
A gene variation that is found predominantly in blacks provides individuals with heart failure with as much protection from death as beta blockers -- one of the most commonly prescribed medications for heart failure -- and extends their lives by several years, according to a study published on Monday in the journal Nature Medicine, the Baltimore Sun reports. The National Heart, Lung and Blood Institute-funded study was conducted by Stephen Liggett, a professor of medicine and physiology at the University of Maryland School of Medicine, and researchers from the Washington University School of Medicine, the University of Cincinnati College of Medicine and the University of Michigan.
In heart failure patients, adrenaline binds to receptors in the heart's cells, stimulating the heart to work harder to pump blood, the Sun reports. For the study, researchers examined the genetic profiles of 2,000 black and white participants in Cincinnati, Kansas City and Atlanta who either had heart failure or were healthy. Researchers noted variations in a particular gene that is known to curb receptor activity in heart failure patients. In most participants, the gene produced a protein called glutamine, but in some participants, the gene produced another protein called leucine. Researchers then conducted an experiment in genetically altered mice, finding that those with leucine "seemed to have a kind of natural beta blocker that reduced the impact of the adrenaline rush that normally prompts a stressed heart to work harder," according to the Sun. The leucine variant was found in 40% of blacks and two percent of whites.
Researchers then tracked 375 black participants for up to eight years, some of whom were treated with beta blockers, and found that 50% of those receiving beta blocker therapies were still alive at the end of the study period, compared with 20% of those who did not receive beta blockers, Liggett said. However, participants with the leucine variant had the same 50% survival rate whether or not they received beta blocker therapy. According to the Sun, the findings suggest that the reason beta blocker therapy is less beneficial in blacks is that "[m]any of them already have nature working for them."
Liggett said the findings could lead to genetic tests to help doctors determine which patients are candidates for beta blocker therapy. "Our goal here is not to take away the physicians' judgment, but to give them some handles to work with, to know when to use a specific drug," he said (O'Brien, Baltimore Sun, 4/21).
An abstract of the study is available online.