February 6, 2006
A University of Michigan Health Minute update on important health issues.
Is high blood pressure in your genes?
Could be, says U-M expert who studies blood pressure genetics - and offers tips on what to do
ANN ARBOR, MI – Eighty-year-old Cleo Upell of Tecumseh, Mich. has high blood pressure. So do three of her daughters – and at least one of her granddaughters.
Families like the Upells are all too common in the United States, where one in four adults has high blood pressure, also known as hypertension. If untreated, the problem creates a much greater risk of heart disease and stroke.
But the Upells are an uncommon sort of family, too. For more than 45 years, they’ve been part of a unique University of Michigan Medical School study that tracks the health of hundreds of families from Tecumseh, a small town close to the Ohio border.
Three generations of Upells and their neighbors are helping U-M researchers make discoveries about blood pressure, including why it seems to run in so many families. The researchers are curious about what genes might be involved in blood pressure, and how those genes can be handed down from generation to generation – an inheritance that no one wants to get. They also hope that by studying those genes, they can help people get earlier diagnosis and better treatment for blood pressure.
Alan Weder, M.D., is one of those researchers. A U-M cardiologist and blood pressure specialist, and member of the U-M Cardiovascular Center, he has spent more than a decade leading the blood pressure genetics part of the Tecumseh study.
Recently, he and his colleagues reported the discovery of a link between high blood pressure and a particular gene variation. Using DNA samples from Tecumseh residents and records of their blood pressure, Weder and his colleagues found that a gene involved in regulating the chemical dopamine in the brain and body is also involved in regulating blood pressure
The discovery may help explain why some people develop high blood pressure and others don't — and why some people's blood pressure increases as they age. It also gives new insight into how the kidneys govern the balance of salt in the body, a crucial task for regulating blood pressure. And, it reveals how a gene already linked to behavior and mental health can play a role in the body, as well as the brain.
“We’re just in the process of identifying genes for hypertension,” says Weder, who cautions that just because someone inherits a risk for high blood pressure doesn’t mean that they’re doomed to have a heart attack or stroke — nor that people whose families have no history of high blood pressure are immune to developing it. That’s because other factors, including diet, exercise, alcohol and age, are also involved.
The combination of factors is what matters — but unlike your genes and your age, you can control factors like what you eat, how often you exercise, whether you smoke and drink, and what you weigh.
Weder notes that the first step is to get your blood pressure tested regularly, especially if people in your family have had high blood pressure, strokes or heart problems. Many people who have hypertension don’t know they have it, and many others who are on the brink of developing high blood pressure have no idea that they are at risk.
People are considered to have high blood pressure when the top number (systolic) of their reading is 140 or higher, or the bottom number (diastolic) is over 90. Anyone whose top number is between 120 and 140, or whose bottom number is between 80 and 90, is considered to be at risk of developing high blood pressure.
If your blood pressure is high, or getting there, Weder says, talk to your doctor about how to change the way you eat, how to quit smoking and cut down on alcohol, and whether and how you should exercise and lose weight.
If those kinds of “lifestyle” changes don’t do enough to bring down your blood pressure, medications can help, says Weder. No matter how you do it, many studies have shown that reducing your blood pressure reduces your chance of heart disease and stroke, which result from the stiffening and weakening of blood vessels that comes from high blood pressure.
Cleo Upell thanks the U-M Tecumseh study for finding her high blood pressure early, and helping her get treatment. “We chose to participate in the study because I knew that they would be running tests, and we would find out if we had any medical problems,” she recalls. “I found out that two of my children had heart murmur, and that I had very high blood pressure. I think high blood pressure does run in my family, and I think it was very good that we took part in this study.”
Cleo’s daughter, 57-year-old Kay Smith, agrees. “My mother’s taken blood pressure medicine as long as I can remember, and a couple of my sisters do too. And I just had to start taking it.” Kay’s 37-year-old daughter also has blood pressure problems, and Kay’s 51-year-old sister Sue Bailey developed it during her first pregnancy and still has it.
Weder notes that the Tecumseh study is studying both the use of medication and lifestyle change to reduce hypertension, and the influence of alcohol and other things that aggravate blood pressure. The ultimate goal is to see how those factors are linked with genetics.
“Studying the genetics of hypertension may allow us to predict who is going to get it before they do. And if we could predict the individual characteristics that would put someone at risk for hypertension, presumably we could figure out strategies to intervene and prevent the disease,” he explains. “Clearly, that would be preferable to just treating it life-long.”
Another possible benefit of the Tecumseh study and other blood pressure genetics research is the development of better treatment for those who have high blood pressure. “Currently, we don’t have a good way of predicting whether someone will respond to a particular lifestyle intervention or a particular drug,” says Weder. “And for that reason, we spend a lot of time trying to apply all interventions to everyone. If we had some way of identifying individuals who would respond to a particular drug or intervention, we could spend our time treating them for what’s really wrong.”
This kind of customized treatment is still in the future, Weder notes, and today’s blood pressure patients need to work with their doctors and nurses to use trial-and-error to find what will work for them. But through research and the help of Tecumseh families like the Upells, he hopes tomorrow’s families won’t have to face a life of high blood pressure and its effects.
About high blood pressure and genetics:
- One in every four American adults has high blood pressure, and many don’t know it. About 90 percent of middle-aged Americans will develop high blood pressure in their lifetime, and nearly 70 percent of people with high blood pressure do not have it under control.
- High blood pressure is also called hypertension. It has few symptoms, but many effects, including a very high risk of heart attacks, stroke and other cardiovascular problems.
- Everyone should have their blood pressure checked regularly. If the top number is higher than 140, or the bottom number is higher than 90, a person has high blood pressure and needs a doctor’s advice about lowering it. If the numbers are slightly lower (120 to 139, or 80 to 89), a person has borderline high blood pressure and should talk with a doctor.
- Many factors make blood pressure go up, including genes that we inherit from our parents, as well as what we eat and drink, how much we weigh, how often and how hard we exercise, and whether we smoke. Blood pressure also tends to go up as people get older, although many young and middle-aged adults have high blood pressure.
- To bring blood pressure down, or keep it from getting too high, doctors often recommend exercise, a diet low in salt and fat, moderate or no alcohol use, no tobacco smoking, and weight control. You can’t control your genes or your age, but there are things you can do to prevent or reduce high blood pressure even if you have genes that might make you more likely to have it.
- Medication can also lower high blood pressure, but it often takes trial and error, or a combination of medicines, to bring down blood pressure once it has gotten high.
- Genetics research, such as that led by the University of Michigan, is trying to find out which genes, and gene variations, are linked to high blood pressure — and use that information to develop tests and treatments for blood pressure problems. The Tecumseh Blood Pressure Study is crucial to this effort; the families taking part have agreed to let U-M researchers study their health, lifestyle and DNA to look for patterns and links to blood pressure.
For information on treatment for high blood pressure at the U-M, contact the U-M Cardiovascular Center toll-free at 888-287-1082.
Find out more on the web at:
U-M Cardiovascular Center: www.med.umich.edu/cvc
UMHS Press Release: U-M blood pressure genetics research
U-M Health Topics A to Z: Hypertension
U-M Health Topics A to Z: Secondary Hypertension
U-M Health Topics A to Z: Diet changes to stop hypertension
U-M Health Topics A to Z: Weight control and blood pressure www.med.umich.edu/1libr/aha/aha_htnwtctr_car.htm
U-M Health Topics A to Z: Low-salt diet
Written by: Kara Gavin
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