Genetic testing sounds like a concept straight out of a science fiction novel. But this chance to peek into the future of your health is an opportunity some people are taking today. People with a family history of certain medical conditions can plan for their futures by understanding their health risks.

Unfortunately, genetic testing isn't as easy as gazing into a crystal ball. For many conditions, genetic testing can give you only an idea of your risk of developing certain conditions. Genetic testing can't tell you if you'll definitely develop cancer or when you'll start to notice symptoms of Alzheimer's disease. Though it might be tempting to get a glimpse of your medical future, realize that the genetic testing results can produce anxiety as easily as they can produce peace of mind.

Genetic disorders are caused by abnormalities (mutations) in your DNA. These abnormalities are formed by the erroneous addition, deletion or substitution of chemicals that make up your DNA. Mutations can occur spontaneously, or they can be inherited from your parents. Mutations can also be caused by your environment, such as exposure to chemicals or radiation.

Your parents pass their genes on to you in the form of chromosomes. Each chromosome contains genes made up of DNA, which guides your cells in creating proteins that are necessary for normal function.

If your DNA contains a mutation, your cells may create proteins that don't work properly or certain proteins may not be created at all. If this occurs with a protein that plays a critical role in your body's functioning, you could develop a medical condition.

Your genes don't cause diseases. Mutations in your genes cause your cells to stop functioning properly, which can then lead to disease.

Your doctor uses genetic testing to predict or diagnose genetic disorders caused by mutations in your genes. You might be interested in genetic testing for a variety of reasons, including:

Genetic testing to determine your individual level of risk
A predictive gene test can determine if you have gene mutations that increase your chances of developing a disease. Though you might not have any signs or symptoms of the disease, if you have a strong family history of a genetic condition, you might be at risk of developing that disorder. Tests for the breast and ovarian cancer genes BRCA1 and BRCA2 are examples of tests that help determine your personal risk of particular diseases. Depending on the results, you may want to take pre-emptive measures, such as preventive mastectomy to prevent breast cancer.

Genetic testing to confirm a diagnosis
Genetic tests can be used to confirm a diagnosis. This can help your doctor devise a plan for your care.

Other uses of genetic testing
Other times when genetic testing might be necessary include: prenatal genetic testing to determine whether a fetus is at increased risk of genetic disorders or physical deformities, genetic testing of newborns for genetic diseases, and genetic testing of potential parents to determine whether they carry genes for a disease that could be passed to future children.

Whether you're a candidate for genetic testing is usually based on your family history. The decision to be tested is made with your doctor after careful discussion about how the test results may or may not help you. If your family history suggests that a gene is passed through your family, your doctor might suggest genetic testing to see how likely you are to develop that condition.

Your doctor may refer you to a genetic counselor — a doctor who specializes in medical genetics. The genetic counselor reviews your family history with you. He or she will discuss genetic testing and points to consider in deciding whether you want to pursue testing.

Genetic testing usually requires a blood sample. Depending on what type of abnormality your doctor is looking for, you may be required to give a hair, skin or other tissue sample, such as cells from the inside of your cheek. Your sample is then sent to a lab for analysis.

Your genetic counselor will go over the results with you. That way he or she can explain exactly what the results mean for your future and what they can't tell you. How long you wait for the results will depend on what sort of testing you have done. Waiting times can vary from a few weeks to several months.

Genetic testing isn't 100 percent predictive. Limitations to the predictive ability of genetic testing include:

• Many genetic tests fail to detect all of the mutations that can cause a disease. Cystic fibrosis, for example, is linked to hundreds of mutations — most of which are rare. Other diseases are caused by mutations that can occur in one of several genes. So while you may test negative by current methods, you may have another unknown genetic defect that increases your risk of a particular disease.
• A positive result doesn't mean you'll develop a disease. Genetic tests can't always tell you with certainty whether you'll develop a disease. They can only tell you that you have a mutation that's shown to be associated with the disease. Your probability of developing the disease may be low or high.
• A negative result doesn't mean you won't develop a disease. Noninherited, sporadic gene changes can occur, or you might carry a different, unknown gene that increases your risk. For example, most cancers result from genetic damage that occurs after birth, such as from smoking or exposure to sunlight.
• A positive test doesn't predict severity of the disease. For example, symptoms of cystic fibrosis range from mild bronchial abnormalities to severe lung, pancreatic and intestinal difficulties, regardless of results from genetic tests.
• Individual genes are only part of the puzzle. Most cancers and common disorders such as heart disease arise from multiple causes, including interactions among several genes. A disease that runs in your family may be the result of shared environmental conditions, not genetics. Factors include diet, smoking and exposure to chemicals, sunlight and other forms of radiation.
• Genetic testing can be expensive. Costs range from less than $100 to a few thousand dollars. Your health insurance may not cover testing.

Learning that you don't possess a gene mutation that predisposes you to a disorder can give you peace of mind. However, this shouldn't prevent you from maintaining your health through balanced nutrition, regular exercise and regular health screenings.

A positive test result allows you and your doctor to monitor your health and start treatment as soon as it's necessary. It might also allow for you to take certain preventive measures. What you do will depend on what disease you're at risk of. Even if effective prevention and therapy aren't available, you can take steps to protect your health, including having regular checkups.

On the other hand, knowing you're at increased risk of a genetic disorder can be stressful and may strain your relationships with loved ones. If you test positive for a gene mutation, it could have emotional and financial implications for your children or your future children.

Undergoing genetic testing may put you at risk of discrimination. If your employer or insurance company knew of your results, would they treat you differently?

Results of your genetic tests are usually kept in your medical records. When you apply for disability, health or life insurance, the company might want to examine your medical records. In some cases, your employer might also have access to your medical records.

Though federal and state laws exist to protect your privacy and to protect you from discrimination, the field of genetic testing is growing quickly, which means laws aren't in place to cover every situation. Consult an attorney if you're concerned about your privacy.

Talk with your doctor and your genetic counselor about the risks and benefits of genetic testing. Consider whether this information will help you, and how you might do things differently if you have the genetic mutation. Ask questions and be sure you have enough information to make your decision. Don't feel pressured by your family or your doctors. The decision to be tested for genetic mutations is yours alone.