By Ed Edelson
FRIDAY, July 17 (HealthDay News) -- Federal researchers have identified five genetic variants associated with high blood pressure in black Americans that could hopefully become targets for therapy to prevent and treat this major risk factor for heart disease and stroke.
Their study, reported in the July 17 online issue of PLoS Genetics, is one of a series being done to pinpoint possible genetic factors in high blood pressure and is the first to focus on blacks, said study senior author Charles Rotimi, a senior investigator at the National Human Genome Research Institute.
"Because of improvements in technology we are now able to look at variants in the entire human genome," said Rotimi, who is also director of the trans-NIH Center for Research on Genomics and Global Health. "Where we find signals, we can now zero in on those areas to see how they work and how they affect blood pressure."
One of the genes identified in the study is known to be a target of one class of drugs for high blood pressure, calcium channel blockers, Rotimi said. The hope is that some of the others will also prove to be targets for prevention and treatment, he added.
"Now it is back to the laboratory," Rotimi said. "We are going to take these genetic findings that we have and find out how they actually work. This is just the beginning."
The study that led to detection of the variants was done on samples of DNA, the molecule that carries genetic information, from 1,017 participants in the Howard University Family Study of families in the Washington, D.C. area who identify themselves as blacks. Half of the volunteers had high blood pressure, and the other half did not. Analysis of more than 800,000 genetic markers found the variants significantly more common in those with high blood pressure.
The findings are significant because high blood pressure is more common among blacks, affecting 39 percent of men and 43 percent of women. Overall, about one-third of all adult Americans have high blood pressure.
One part of the research effort was a similar genetic analysis done on 980 people from West Africa, the home area of the ancestors of most black Americans. That study confirmed that some of the genetic variants seen in black Americans are also found in West African people, the report said.
But the genes are not unique to people of African origin, Rotimi said. Two of the variants have been found to be associated with high blood pressure in the general population, he said.
All five variants are associated with high systolic pressure, the higher of the reading, the pressure when the heart contracts, Rotimi said.
The study is important because "it is one of only a very few of the large genome-wide studies done on an African-American population," said Michael Christman, president and chief executive officer of the Coriell Institute for Medical Research, a nonprofit New Jersey organization. "Almost all the available genetic information stems from populations of western European origin."
The actual genotyping was done at the Coriell Institute, Christman said.
The institute has been busy with similar genetic studies recently, Christman said. "Genome-wide studies are going on all over the place," he noted.
These provide findings that can eventually be applied to medical practice, Christman said. "Emerging studies indicate how genetic makeup shows how people will respond to drugs," he said. "So it's important that there be more of these studies."
For basic facts on high blood pressure, go to the U.S. National Library of Medicine.
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