September 24, 2001 CHICAGO (AP) - Researchers have identified a marker on the male chromosome that may partly explain why high blood pressure affects more men than women until middle age. The discovery supports the belief that genetics contributes to the risk of developing the condition.
The marker is a genetic variation that was found in 51 of 155 men studied in southern Poland, or about 30 percent of participants.
In men who tested positive for the marker, average blood pressure readings were 145/90; a reading of 140/90 is considered high.
Their average systolic pressure - the higher number, measuring pressure inside arteries when the heart beats - was 10 points higher than in men without the marker. Diastolic pressure - the lower number, measuring pressure between beats - was five points higher.
A report on the study by University of Glasgow researcher Fadi J. Charchar was prepared for presentation Sunday in Chicago at the American Heart Association's fall conference on high blood pressure research. Scientists from Silesian School of Medicine in Zabrze, Poland, contributed to the study, which was funded by the British Heart Foundation.
An estimated 50 million Americans age 6 and up have high blood pressure, which significantly increases the risk of heart attacks, strokes and other cardiovascular ailments. The prevalence in adults is estimated at 25 percent in the United States and other developed countries, and may be slightly higher in Poland, said Dr. Anna Dominiczak, leader of the Glasgow research group.
From age 20 to 34, men are more than twice as likely to have high blood pressure than women. The disparity remains until around age 55, when many women have gone through menopause and lose the suspected protective effect of female hormones.
Weight, age and sensitivity to salt are thought to be contributing factors.
Exploring the suspicion that genetics also plays a role, the researchers collected DNA and used an enzyme that helped them distinguish two forms of the Y chromosome, which determines male gender.
Dr. David Faxon, president of the American Heart Association, called the study useful in enhancing knowledge about high blood pressure but very preliminary.
"There are probably many, many different genes that are responsible for causing high blood pressure," Faxon said.
Once the genes are identified, he said, the next step would be to develop targeted drug treatment or alterations in genes to try to prevent high blood pressure.
However, "that's way downstream," Faxon said.
Copyright 2001 The Associated Press. All rights reserved.
