According to the Food and Drug Administration (FDA), which regulates the manufacturers of genetic tests, and the Centers for Disease Control and Prevention (CDC), which promotes health and quality of life, some of these tests lack scientific validity, and others provide results that are meaningful only in the context of a full medical evaluation. The FDA and CDC say that due to the complexities of both the testing and the interpretation of the results, genetic tests should be conducted in registered laboratories that are certified to handle specimens, and the results may need to be interpreted by a doctor or trained counselor who understands the value of genetic testing for a particular situation.

Genes and Genetic Tests

Inside the cells of your body, chromosomes carry your genetic blueprint. Your chromosomes are passed to you by your parents; they contain genes made of DNA (deoxyribonucleic acid). Your genes determine characteristics like eye color or height, and contribute to your chances of getting certain diseases.

Genetic tests examine genes and DNA to see if they indicate the presence of, or risk for developing, particular diseases or disorders. Several different types of tests are available. Some look at the number and shape of chromosomes to find obvious abnormalities. Others look for small unusual portions of individual proteins or variations in DNA. Genetic tests might look at one or a few variations in DNA or a million or more variations at one time. Typically, these tests require a blood sample, a swab from inside your cheek, or saliva. In DTC genetic tests, you collect the sample at home and then send to a laboratory for analysis. No physician’s prescription is required. Prices of DTC genetic tests can range from less than $100 to a few thousand dollars. Sometimes, they are offered for “free” as long as the consumer agrees to buy other products from the seller, like nutritional supplements.

Interpreting Test Results

The results of genetic tests are not always “yes or no” for the presence or the risk for developing disease, which make interpretations and explanations difficult. In most cases, diseases occur as a result of interaction among multiple genes and the environment — for example, a person’s lifestyle, the foods they eat, and the substances to which they’re exposed, like sunlight, chemicals, and tobacco. The interactions of these factors in contributing to health and disease can be very complex. Even health care experts are just beginning to understand the relationships among these factors. That’s why it is important to gather and analyze this information with a qualified health care provider so you can be sure genetic data is accurate and correctly used.

Many genetic tests look at only a small number of the more than 20,000 genes in the human body. A positive result means that the testing laboratory found unusual characteristics or changes in the genes it tested. Depending on the purpose of the test, a positive result may confirm a diagnosis, identify an increased risk of developing a disease, or indicate that a person is a carrier for a particular disease. It does not necessarily mean that a disease will develop, or if it does, that the disease will be progressive or severe.

A negative result means that the laboratory found no unusual characteristics or changes in the genes it tested. This could mean that a person doesn’t have a particular disease, doesn’t have an increased risk of developing the disease, or isn’t a carrier of the disease. Or it could mean that the test didn’t examine or has missed the specific genetic changes associated with a particular disease.

In short, the FDA and CDC say that genetic testing provides only one piece of information about a person’s susceptibility to disease. Other factors, including family background, medical history, and environment, also contribute to the likelihood of getting a particular disease. In most cases, genetic testing makes the most sense when it is part of a medical exam that includes a person’s family background and medical history.

Company Claims

Some companies claim that DTC genetic tests can measure the risk of developing a particular disease, like heart disease, diabetes, cancer, or Alzheimer’s. But the FDA and CDC say that risks of such diseases come from many sources, not just genetic changes, and that valid studies are necessary to prove these tests give accurate results. Having a particular gene variation doesn’t necessarily mean that a disease will develop; likewise, not having a particular gene variation doesn’t necessarily mean that the disease will not occur.

Some companies also may claim that a person can protect against serious disease by choosing special foods and nutritional supplements. Consequently, the results of their DTC genetic tests often include dietary advice and sales offers for “customized” dietary supplements and cosmetics. The FDA and CDC say they don’t know of any valid scientific studies showing that genetic tests can be used safely or effectively to recommend nutritional choices or to genetically customize dietary supplements or cosmetics.

As for claims that the tests can assess a person’s ability to withstand certain environmental exposures, like particular toxins or cigarette smoke: Be skeptical. The FDA and CDC aren’t aware of any valid scientific studies that show that genetic tests can be used to predict whether a person can withstand environmental exposures.

Some companies have claimed that DTC genetic tests can give information about how a person’s body will respond to a certain treatment, and how well people will respond to a particular drug. This claim is based on current medical research that shows differences in drug effectiveness based on genetic make-up. But, say federal experts, while these tests may provide some information your doctor needs or uses to make treatment decisions for a specific condition, they are not a substitute for a physician’s judgment and clinical experience.

If You’re Considering a DTC Genetic Test

According to the FDA and CDC, DTC genetic tests aren’t a suitable substitute for a traditional health care evaluation. Medical exams that include conventional laboratory tests like blood chemistry and lipid profiles are a more appropriate starting point for diagnosing diseases and assessing preventive measures. Nevertheless, if you are considering using a DTC genetic test: 

• Talk to your doctor or health care practitioner about whether it might provide useful information about your health, and if so, which test would be best. Make sure you understand the benefits and limits of any test before you buy it — or take it. 
• Ask your doctor or a genetic counselor to help you understand your test results.
• Discuss the results of your test with your doctor or health care practitioner before making dietary or other health-related decisions. Genetic test results can be complex and have serious implications. It’s a bad idea to make any decisions based on incomplete, inaccurate, or misunderstood information. 
• Protect your privacy. Before you do business with any company online, read the privacy policy: It should specify how the company secures the information it collects, how it will use your information, and whether it will share your information with third parties. 
• While most other home-use medical tests undergo FDA review to provide a reasonable assurance of their safety and effectiveness to date, FDA has not authorized any DTC genetic tests for marketing.

For More Information

The Federal Trade Commission works for the consumer to prevent fraudulent, deceptive, and unfair business practices in the marketplace and to provide information to help consumers spot, stop, and avoid them. To file a complaint or to get free information on consumer issues, visit ftc.gov or call toll-free, 1-877-FTC-HELP (1-877-382-4357); TTY: 1-866-653-4261.

The Food and Drug Administration is responsible for protecting the public health by assuring the safety, efficacy, and security of human and veterinary drugs, biological products, medical devices, our nation’s food supply, cosmetics, and products that emit radiation. The FDA also is responsible for advancing the public health by helping to speed innovations that make medicines and foods more effective, safer, and more affordable; and helping the public get the accurate, science-based information they need to use medicines and foods to improve their health. For more information from the FDA, call toll-free 1-800-INFO-FDA. Copies of press releases and consumer alerts are available from the FDA’s website at www.fda.gov.

The Centers for Disease Control and Prevention is one of the 13 major operating components of the Department of Health and Human Services, which is the principal agency in the United States government for protecting the health and safety of all Americans and for providing essential human services, especially for those people who are least able to help themselves. For further information about CDC,visit www.cdc.gov, call toll-free 1-800-CDC-INFO, or e-mail cdcinfo@cdc.gov.

Produced in cooperation with the Food and Drug Administration (FDA) and the Centers for Disease Control and Prevention (CDC).