两条损害黑人心脏的基因被发现(英文)
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2002年10月11日
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Genetic double-whammy in blacks bad for their heart
BOSTON (AP) -- A study published Thursday may help explain why blacks are more likely to experience congestive heart failure than whites, researchers say. (波士顿--研究人员周四公布的一项研究结果有助于解释为什么黑人比白人更容易出现充血性心衰)
Two pairs of genes that rarely occur together in whites generate a tenfold risk for heart failure among black people who have both the gene pairs, according to the study in the New England Journal of Medicine.
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The genetic combination plays a role in one-quarter of the cases of congestive heart failure diagnosed each year among blacks, said Dr. Stephen B. Liggett of the University of Cincinnati College of Medicine, who was a leader of the study.
Liggett and his colleagues found that a single pair of genes that does nothing bad by itself can double the risk created by a second pair.
About 5 percent of U.S. blacks have both sets of genes, Liggett said. But it is far rarer among whites.
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In an accompanying editorial, Dr. Roger J. Hajjar of Massachusetts General Hospital called the study "provocative," but said the researchers hadn't proven cause and effect.
Doctors have long known that blacks are more likely than whites to suffer from heart diseases and certain other illnesses, and are more likely to die from them. Some researchers have suggested that blacks receive inferior care, perhaps because of unconscious prejudice among doctors.
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An analysis of 81 studies released Wednesday as part of a campaign by major health foundations to close the racial health gap found that the evidence that minorities get inferior cardiac care is compelling.
Liggett's study, however, is part of a growing body of research indicating that at least part the racial gap can be explained by genetics.
Nearly 4.8 million Americans have congestive heart failure. It affects about 3.5 percent of all black men, 3.1 percent of black women, 2.3 percent of white men and 1.5 percent of white women, according to the American Heart Association.
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That would mean about 733,500 blacks have the disease. It shows up earlier and is more likely to have serious complications in blacks than in whites. Also, blacks do not get as much benefit from or need higher doses of ACE inhibitors and beta-blockers, two common groups of medicines for heart disease.
There is no one explanation for those differences. High blood pressure, diabetes, high cholesterol, smoking and obesity all increase the risk.
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Discrimination, lack of access to care and other societal inequities are indeed a problem -- but may not be the main reason for the gap, said Dr. Clyde W. Yancy of the University of Texas-Southwestern Medical Center in Dallas.
"When you control for those variables, there is still more heart disease in African-Americans. Particularly this disease called heart failure," he said.
One of the gene pairs in question increases production of a chemical that increases blood pressure, heart rate, and the heart's contraction and relaxation. The other gene pair makes heart cells which take up the chemical, norepinephrine, more sensitive to it.
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Since the pair producing excess norepinephrine is 10 times as common among blacks as among whites, the combination is also far more common among blacks.
In the study, two of the 84 healthy blacks had the combination, compared with 15 of 78 blacks with heart failure. Two out of 105 healthy whites and three of 81 with heart failure had the gene combination.
Yancy said the next step is to find what other genes are involved, and how they affect patients' response to various drugs., 百拇医药