Mutation Makes Good Medicine

ScienceNOW Daily News ^ | 21 April 2008 | Kelli Whitlock Burton

[neverdem]

Scientists have discovered a genetic mutation that might extend the lives of many African Americans after heart failure by mimicking a common class of drugs called beta blockers. The findings could explain why clinical trials of the drugs have shown little benefit to African-American patients.

The heart doesn't stop beating during heart failure. Instead, it stops pumping blood efficiently. The condition can be caused by a number of diseases--including diabetes and hypertension--that keep the heart from filling with blood or decrease blood flow from the heart to the rest of the body. As the heart falters, the body releases adrenaline to keep the organ pumping. Too much adrenaline overworks the heart, and eventually the organ gives out.

Beta blockers halt this process by blocking adrenaline receptors and slowing the heart rate. However, studies suggest that the drugs don't work in many African Americans. To figure out why, researchers at the University of Maryland, Baltimore, and Washington University in St. Louis, Missouri, took a close look at GRK5, one of the receptor proteins in the heart that responds to adrenaline. After sequencing DNA from 96 heart-failure patients, the team found that 40% of African Americans in the study had a mutation in GRK5. Only 2% to 3% of participants of European or Chinese descent had this variant, called Leu41.

The researchers then followed 375 other African-American heart-failure patients with and without the mutation until they died or received a heart transplant, an average period of 30 months. Some patients took beta blockers and some didn't. Of those who did, patients with Leu41 had the same survival rate as those without the mutation. The surprising finding, however, was that among patients who didn't take the drugs, those with Leu41 lived almost twice as long as those without the mutation. Reporting online this week in Nature Medicine, the team says it believes the mutation mimics beta blockers, slowing heart rate by blocking GRK5's ability to respond to adrenaline.

"This work suggests that the reason it's been hard to demonstrate a benefit [of beta blockers] in African Americans is that almost half of them are already getting the benefit naturally,” says David Kass, a cardiologist at Johns Hopkins University in Baltimore, Maryland, who was not part of the study. But that doesn't mean that beta blockers are useless for patients with Leu41, says Gerald Dorn, a senior author of the study and a cardiologist at Washington University School of Medicine. Beta blockers work against several different types of heart disease, so "I'm not willing to say that having the protective gene is equal in every way to beta-blocker therapy."

Related site

• More about heart failure and beta blockers

[Coyoteman]

A beneficial mutation?

But we've been told by the anti-science crowd on these threads that mutations can't be beneficial.

Placemarker.

[neverdem]

Tastes Like Chicken - Growing Meat Without Growing Animals

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FReepmail me if you want on or off my health and science ping list.

[SunkenCiv]

Scientists have discovered a genetic mutation that might extend the lives of many African Americans after heart failure by mimicking a common class of drugs called beta blockers.

Nothing will be done until, on some awards show, Kwame West condemns GWB for making harmful genetic mutations for blacks. *