How Do Direct-to-Consumer Genetic Health Risk Tests Work?

At-home genetic health risk tests can detect your predisposition to a variety of conditions.

DNA sample from a direct-to-consumer genetic health test being added to a petri dish.

Updated on May 26, 2022.

In April 2017, the U.S. Food and Drug Administration (FDA) authorized 23andMe, a genetic testing service, to release Personal Genome Service Genetic Health Risk (GHR) tests. It was the first time the FDA approved a direct-to-consumer test for genetic predisposition to different health conditions.

Here’s how it works: After you take saliva sample, you mail it to a lab where your DNA is tested for hundreds of thousands of genetic variants. The presence or absence of certain variations may be linked to an elevated risk of developing certain health conditions.

In its initial iteration in 2017, 23andMe tests checked for genetic variants associated with 10 diseases or conditions. In the years since, more diseases have been added.

Here are some of the conditions at-home GHR tests can check for:

  • Parkinson’s disease, a progressive disorder of the nervous system that affects movement
  • Late-onset Alzheimer’s disease, a brain disorder that causes problems with memory, thinking, and behavior
  • Celiac disease, an immune reaction to the protein gluten found in wheat, rye, and barley
  • BRCA1/BRCA2, specific genetic variants that may increase the risk for breast, ovarian, prostate, and other cancers
  • Hereditary Hemochromatosis, a condition in which too much iron builds up in the body, rising to potentially toxic levels
  • Familial hypercholesterolemia, very high cholesterol levels that increase the risk for early heart disease

These tests provide information, but that's just a piece of the larger picture. Detection of a certain genetic variant doesn't automatically mean you'll develop the condition. Many factors, including your environment and lifestyle, also contribute.

Among the requirements placed on 23andMe by the FDA has been the use of consumer-friendly language in GHR test instructions and reports. A readability study of the materials suggested users understood more than 90 percent of the information.

GHR tests are not perfect, and risks of false positives do exist. (A false positive is a result that suggests the presence of a marker for a certain disease where none actually exists.)

Remember that results of a GHR test should not be used for diagnosis. The FDA states that users should consult their healthcare provider and consider speaking with a genetic counselor about any questions and concerns and before making medical decisions regarding their test results. 

Article sources open article sources

US Food and Drug Administration. FDA allows marketing of first direct-to-consumer tests that provide genetic risk information for certain conditions. April 6, 2017.
23andMe. 23andMe genetic health risk reports: what you should know. Accessed May 17, 2022.
US Food and Drug Administration. Direct-to-Consumer Tests. Last updated December 20, 2019.

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