Thursday, 22 September 2005 00:00

Genes May Predispose Some Men to High Blood Pressure

THURSDAY, Sept. 22 (HealthDay News) -- Being male may often mean being born with the risk of higher blood pressure, a new study suggests, and this appears to be especially true for black males.

In the study, British researchers found that genes on the Y chromosome affect blood pressure in young boys -- a difference that persists after puberty, especially in black males.

"Variations on the Y chromosome have an effect on the blood pressure of young boys," said lead researcher Fadi J. Charchar, a lecturer in cardiovascular science at the University of Glasgow. "Those with one variation tend to have higher blood pressure, not only at puberty, but it goes on after puberty," he added.

Charchar was to present the study findings Thursday at the American Heart Association's annual high blood pressure conference, in Washington, D.C.

For the study, the researchers collected genetic material from 105 black boys and 156 white boys. They then studied the effect of genetics on the age at which the boys experienced the biggest spurt in growth. The two genotypes they studied are called the HindIII(-) and the HindIII(+).

In addition, they measured the duration of growth from two years before the growth spurt until the boys grew less than 2 centimeters a year.

The researchers found that boys with the HindIII(-) gene had a growth spurt earlier than did boys with the HindIII(+) gene. In addition, HindIII(-) boys also had longer growth spurts compared with those with the HindIII(+) gene -- 4.9 years vs. 4.5 years.

Moreover, boys with the HindIII(-) gene had higher blood pressure compared with boys with the HindIII(+) gene -- systolic pressure that was 2.6 mm Hg higher and diastolic pressure 2.3 mm Hg higher.

And this boost in systolic and diastolic blood pressure continued after puberty, especially in blacks, Charchar's team found.

Based on these findings, Charchar believes this difference in genes can be used to identify those males likely to develop high blood pressure. "Even from a younger age, we have a way to track younger males and see who is going to be at a higher risk," he said. "This is going to be very important for preventive methods and treatment."

One expert sees the finding as an example of the link between genes and so-called environmental factors, such as lifestyle.

"We know that blacks have more of a problem with blood pressure than whites," said Dr. Howard Weintraub, co-director of the New York University lipid treatment program and an associate professor of medicine at the NYU School of Medicine.

For years, scientist have been trying to find out what causes blacks to be especially susceptible to high blood pressure, Weintraub said. "Genes are entities that can be modified environmentally," he noted. "It may be that lifestyle unmasks a genetic predisposition to high blood pressure."

"If this is the kind of a person who really watched what they ate, didn't get fat and exercised, their blood pressure would be borderline," Weintraub said. "The same person without a genetic disposition would have a lower blood pressure."

Another expert questioned the accuracy of the study findings, saying there were too few boys in the trial.

"It's interesting but it must be considered preliminary," said Dr. Harlan M. Krumholz, a professor of cardiology at Yale University Medical School. "The group is a relatively small group and so I would want to see this validated to be confident is it true and important."

More information

The American Heart Association can tell you more about high blood pressure.