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April 8, 2013

Heart Medicine Gene

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Genetics researchers have debunked a racial myth about who might benefit from a widely used heart failure medication. As this ScienCentral video reports, the finding will eventually allow personalized treatments for this devastating disease.

[If you cannot see the youtube video below, you can click here for a high quality mp4 video.]

Interviewees: Wanda Pate, has heart failure;
Stephen Liggett, University of Maryland School of Medicine;
Charles Rotimi, National Institutes of Health
Length: 2 min 00 sec
Produced by Joyce Gramza
Edited by Chris Bergendorff
Copyright © ScienCentral, Inc.

Window of Opportunity

At 37 years old, respiratory therapist Wanda Pate never expected to have congestive heart failure. Typical of a healthcare professional, she thought she knew what was causing her to feel tired and sick for several weeks.

"I really thought it was something related to reflux or some GI- [gastrointestinal] related problem, and I was waiting for an appointment with a GI doctor," says Pate.

But instead, chest pains and numbness and tingling in her arms and fingers sent her to the emergency room.

Pate says she was more than shocked to receive the diagnosis: "It was overwhelming. Did a lot of crying at first. Just really unbelievable."

Pate is of African American ethnicity, and fortunately, her skin color did not get in the way of her treatment. She's doing better with the help of beta-blockers, drugs commonly used to treat heart failure.

Previous studies had suggested that beta-blockers were less effective in African Americans and that other drugs, such as BiDiL, benefited them more. However University of Maryland geneticist Stephen Liggett points out that those studies were based on people's self-described race, rather than their actual genetic makeup, leading down a path of what he calls "race-based medicine" — a dangerous path for such a devastating disease.

"This is one of those diseases where the sort of hit-or-miss, one-drug-fits-all approach is probably not our best way to go about treating," says Liggett. "Because there's a very small window of opportunity for us to get it right.

"It is a syndrome which is characterized by the inability of the heart to pump the appropriate amount to perfuse the rest of the body and provide the ability for individuals to even walk across the room when heart failure gets really severe," he explains. "And within five years, 50 percent of individuals who have heart failure have died, and within the first year of diagnosis, 20 percent die.

"We need to become much more sophisticated in looking at the specific genes," Liggett says.

Surprising Finding

So Liggett and collaborator Gerald Dorn of Washington University in St. Louis led a study to do just that.

After studying the DNA sequences of over 2,000 people suffering from heart failure, the researchers discovered that 40 percent of the African American patients had a different version of a gene that actually imitates beta-blockers and thus protects them as if they were already taking the drug.

"That was quite a bit of a twist I would say, as compared to what we've seen before in some other pharmacogenetic studies," Liggett says. "We found that in mostly African Americans, there is another form of this gene we are looking at which actually mimics the drug that is often used to treat heart failure, so those individuals do not need the drug at all."

As he and Dorn wrote in the journal Nature Medicine, while that version is more common in self-described African Americans, it occurs in people of all ancestries, and there are many African Americans who do not have it. For those who do not have the gene and do not take beta-blockers, 80 percent die in four to six years, he says.

Dispelling Racial Assumptions

Charles Rotimi, who directs the new NIH Intramural Center for Genomics and Health Disparities, believes genetic studies like this one will dispel racial assumptions and lead to treatments tailored to each individual's genes.

Chest x-ray
"What this study shows very clearly — which I do hope to share the message with the public — that it will help us to better appreciate that if we use the group label called African-American or Hispanic or Asian-American or European-American, that at the level of treatment of an individual, those descriptors are not precise enough to give us information that we need," Rotimi says.

"The danger in not finding this out is that we do make assumptions, like have been made about beta blockers: that they don't work in African Americans," he says. "So if a physician is going to prescribe a beta blocker, they're hesitant when they see the skin color instead of looking at that individual and saying, ‘Does this individual carry that variant?'"

"For example," Rotimi explains, "it's entirely possible that I'm a carrier of a particular variant that my mother doesn't carry. So if you're using my mother as information to treat me, then it would be inadequate for that particular drug, although she's my mother. So I think that is a level that we need to get to. We need to understand our diversity. We need to cherish it, and we need to study it, and we need to understand the implication of that diversity at the level of drug, at the level of understanding disease distribution, as we go from one human population to the other."

"African Americans cannot be treated as if they are one group. You have to look at the individual in front of you if you are the doctor prescribing the beta blocker or any other drug, for that matter," he says.

Further Studies

Liggett and his team are now conducting further clinical studies aimed at developing personalized treatments for heart failure. Pate agreed to participate not only because she's supportive of biomedical research, but also because as the mother of two, she wants to know "if it's something that I'm passing on to them, to know if it's something I inherited so that we can better treat it," she says.

Liggett says, "This study will not only be used to confirm the previous study that we just published, but also we'll begin to add additional genes to see how well we can refine our predictive ability."

Pate also has a message for the public. "I think being in the health care profession, you think you know everything already and you self-diagnose," she says. She urges "getting to the doctor as soon as you realize that something's not right."

She also emphasizes the importance of a healthy lifestyle. "To eat healthy, to do exercise, it probably sounds like a cliché, but it's really, really important to take care of yourself," she says.

This research was published in the journal Nature Medicine, advance online publication, April 20, 2008, and funded by the National Heart, Lung and Blood Institute of the National Institutes of Health.

       email to a friend by Jamie Gardella and Joyce Gramza

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