22 April 2008
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.
Reprinted with kind permission from
http://www.kaisernetwork.org.
Article URL: http://www.medicalnewstoday.com/articles/104893.php