As scientists unveil more secrets concealed in the human genome, it’s becoming clear that genetic tests may help doctors detect early-stage cardiovascular disease (CVD). And, perhaps a decade from now, heart therapy may become a matter of modifying our genes to prevent or halt the disease.
Sound far-fetched? It was, until just a few years ago when researchers finished mapping the 30,000 to 80,000 genes it takes to be human. Since then, they’ve turned their attention to finding specific genes that cause our cells to malfunction. That’s already led to genetic tests for several major CVDs. More are on the way.Tales from the heart
Even more exciting are the gene-based therapies for heart disease under development. At least three dozen clinical trials of such therapies on humans have been performed since 2000.
Some trials involve injections of so-called therapeutic genes into damaged hearts. Others use experimental drugs that modify damaged genes suspected of triggering high blood pressure.
But most important, understanding the molecular underpinnings of CVD will allow doctors to forecast our probable heart disease risks in plenty of time to correct them. That’s promising for two reasons. First, susceptibility to heart disease can be passed down from one generation to another.
In fact, researchers have developed a test for a mutation in the gene that produces angiotensinogen, an enzyme that helps regulate blood pressure. People with this rare mutation are predisposed to hypertension. Another test can find an uncommon but lethal gene mutation that can interrupt electrical activity in the heart, placing a person at high risk of a heart attack.
Second, some heart disease seems to be caused by the way our genes interact with what we eat, drink or breathe. So even though a person may not be born with culprit genes, a high-fat diet can still damage certain cells—let’s say, for example, those that help thin the blood. Once this natural protection erodes, dangerous blood clots could form, increasing the risk of heart attack or stroke. Tip of the iceberg
For now, only a few genetic tests for CVD risk factors are available, and it will take several more years of study before most of us will benefit from this new medical frontier. That said, some of the research that’s under way includes:
- Cholesterol filters. Scientists can reverse familial hypercholesterolemia—or inherited high cholesterol—by injecting helper genes into a patient’s faulty liver to make it filter out more “bad” low-density lipoprotein (LDL) cholesterol.
- Vessel builders. By harnessing a process called angiogenesis—the body’s ability to grow new blood vessels—certain genes may someday be stimulated to grow new cells that can help repair diseased blood vessels. Already, growth-factor genes are being injected into heart muscle to relieve angina pain.
- Artery openers. Doctors hope to learn how to better control the many genes involved in atherosclerosis—the buildup of fatty plaques on artery walls—so that this dangerous precursor to heart attacks can be eliminated.
- Stroke blockers. Several “candidate” genes thought to be involved in strokes are being closely examined, leading doctors to believe that stroke risk can be lowered, if not eliminated, by preventive therapy.