Beating Bad Health Genes

By Gordon, Sandra

Do you have a relative with heart disease, cancer, or other major chronic health problem? If so, it pays to learn if you're at increased risk, too.

Given recent medical progress, you can do so with some degree of accuracy.

That's because, in part as a result of the Human Genome Project -- a 13-year government effort to decode the approximately 30,000 genes in human DNA -- specific screening and genetic blood tests for some conditions now are available. These tests identify precursors to disease and genetic mutations that may be responsible for some illnesses.

More than 4,000 diseases are caused by genetic abnormalities. Some illnesses, including many cancers, are caused by a mutation in a gene or a group of genes, according to the National Human Genome Research Institute (NHGRI). These gene variations either occur at random or because of exposure to something in the environment. Other genetic disorders are passed down through families.

Most genetic disorders are caused by small variations in genes in combination with environmental factors, the NHGRI says. Just about all diseases are caused by an interaction of genes and environment. The environmental factor could be a virus, a harmful chemical, poor nutrition, or a risky behavior. Genetic variations don't cause disease but control how susceptible a person is to  environmental factors.

Genetic testing

Genetic testing usually involves taking a sample of someone's blood, skin, or body fluids. The sample is examined for any abnormality that indicates a disease or a disorder, the NHGRI says.

Testing can help you make decisions about prevention. You may decide to change your health habits to reduce your risk for developing a particular disease. Even if you have a known genetic mutation for a particular disease, your chance of developing it can vary from 5 to 85 percent. The difference depends on how strong a particular gene is, says Kelly Ormond, M.S., CGC, a genetic counselor in Chicago.

Trace your family medical tree

The first step to figuring out your disease risk is to make a list or draw a diagram of your family tree. Go back as far as your great grandparents. Include parents, aunts, uncles, nieces, and nephews. For each family member note who had what particular condition, how old he or she was when diagnosed, and if or when he or she died of it.

According to the CDC, these critical features of a family history may increase your risk for a particular disease:

  • The disease occurred 10 to 20 years earlier than most people get the disease.

  • The disease occurred in more than one close relative.

  • The disease occurred in a gender not usually associated with the disease. An example is breast cancer that appears in a man.

  • Certain combinations of diseases occurred within a family. Examples are breast and ovarian cancer, or heart disease and diabetes.

In general, your risk for heart disease and stroke may be increased if you have a first-degree male or female relative, such as a parent or sibling, who's diagnosed with heart disease before age 55 or stroke before age 60.

"For most types of cancer, your risk is greater if a first-degree relative was diagnosed before age 50. With female breast cancer, however, your risk also may be increased if you have a second-degree relative linked by a male, such as your father's mother or sister, who was diagnosed with the disease before age 50," says Charis Eng, M.D., Ph.D., a Cleveland genetic medicine specialist.

Talk with your doctor

After you draw up your family tree, talk with your health care provider. You can discuss the diseases or conditions that you have are highlighted.

"All physicians take a general family history. But the specific information you provide may change the way they manage your health care," Ormond says. "Your physician may ask additional questions and refer you to a geneticist or genetic counselor for a more in-depth risk assessment."