Wednesday, April 23, 2008

Heart Protective Gene Found in Some Blacks

According to a study published online April 20, 2008 in Nature Medicine, approximately 40% of blacks may be naturally protected after heart failure. Researchers have uncovered a gene variant that appears to act like a beta blocker (a heart protective drug), adding years to the lifespan of blacks with heart failure; possibly negating the need for drug therapy. Dr Stephen B Liggett (University of Maryland, Baltimore) and colleagues surmise: “The findings may help explain why beta blockers don't appear to benefit some African Americans.”

Beta blockers are prescribed to patients as the result of evidence based practice. They are routinely used for the treatment of heart failure, arrhythmias, and following heart attacks. Past studies have shown that African Americans don’t respond to Beta blockers as well as whites. Sharon Cresci (Washington University, St Louis, MO) says: "I think this is so exciting. I believe this gene has significantly contributed to the discrepancies that have been found in such studies. If researchers were able to go back and genotype patients from their studies, it would probably help clarify some of their findings." Dr. Cresci is the second author of the study, and her comment was provided during an interview with Heartwire.

The researchers sequenced the DNA of 96 people of European American, African American, or Chinese descent to look for differences in two specific heart genes - GRK2 and GRK5. They found that everyone had the same gene with the exception of African Americans. Forty one percent were found to possess a variant, known as GRK5-Leu41. Next, they compared survival rates of those with and without the variant in 375 African Americans with heart failure. Not all were taking beta blockers during the study. Those who were not taking the drug, and had the gene variant, lived twice as long as those with the more common gene sequence, and did not take beta blockers. For those taking beta blockers, survival rates were the same, showing that beta-blockers provided no added benefit when the gene variant is present.

Dr. Cresci feels it is too soon to advocate gene testing to decide if blacks with heart failure should or should not take beta blockers, but the group is planning more research. The potential also exists for using GRK5-Leu41 as an actual treatment for heart failure. The study results may add to the growing use of genetic testing for individualized delivery of healthcare.

"This is a step toward individualized therapy. "Medical research is working to identify many genetic variants that someday can ensure that patients receive the medications that are most appropriate for them. Right now, we know one variant that influences beta blocker efficacy, and we are continuing our research into this and other relevant genetic variants”, says Dr. Cresci.

Nature Medicine April 20, 2008

To learn more about heart failure, visit the American Heart Association. ◦