Thanks to at-home genetic testing, families are able to trace their lineage through generations, identify their geographic origins and even find lost relatives. Genealogy information once available only through family anecdotes and government records is now traceable with high precision through a tiny drop of blood or a swab of the cheek. The market for over-the-counter genetic tests has surged in recent years, providing easily accessible testing for ancestry, food sensitivities and even pet health. While these widely available kits provide answers to our most elusive queries, their results can raise additional questions and be difficult to interpret. 

Genetic counselors are a special group of health care workers who can help decipher genetic testing results. Their specialized training in both genetics and counseling allows them to provide medical and emotional support and genetic health education. Johns Hopkins Medicine has more than 30 genetic counselors who work in a range of specialty areas. Among them are Katie Forester, Kelsey Guthrie, Kristen Miller and Karen Raraigh, who gathered to share the top five things consumers should know about over-the-counter genetic testing.

1. Over-the-counter genetic tests are sometimes called direct-to-consumer tests, which means they do not require a physician order or prescription. These kits are not designed to be diagnostic medical tests. These tests can be falsely reassuring or falsely alarming because they are typically done without considering the patient’s medical or family history, and are nearly always performed without pre- and post-test counseling by a genetics professional.

2. Many genetic test kits analyze several categories of genetic changes: 

Carrier status for recessive disorders, such as cystic fibrosis or sickle cell disease. Individuals become carriers for recessive disorders when one parent passes down a mutated gene and one passes down a normal gene. Genetic test kits look only for the presence of a few common mutations in these genes, and would have a much lower detection rate than carrier screening tests given by health care professionals in a clinical setting, especially for people who are not of white European or Ashkenazi Jewish descent. 

Markers or traits that might influence physical characteristics or health. These traits are often the result of a single DNA letter change called a polymorphism, which can be commonly seen within a population. Some polymorphisms have been linked to a higher risk for different medical conditions, such as Alzheimer’s disease. However, even if someone carries a polymorphism for Alzheimer’s disease, this is not necessarily predictive of whether or not they will develop this condition. Conversely, just because a person tests negative for a polymorphism does not mean they cannot develop the condition.  

Genetic health risks. Some genetic test kit companies screen for a limited number of conditions that may directly impact a person’s health, such as hereditary breast and ovarian cancer. This testing evaluates only a limited number of genetic variants more common in certain ethnic populations, and is not comprehensive to investigate all causes (including other genetic causes) of these conditions. Therefore, if you or a family member has a history of one of these conditions, you should see a genetic counselor.

3. Some genetic test kit companies provide information about the ancestry of an individual. This testing looks for genetic markers that can be traced to different geographical areas to give a rough estimate of a person’s ancestry.

4. There are many things to consider when deciding whether to submit information to an at-home genetic test. Some people may learn information about their family that they are not expecting, such as surprising ancestry or unexpected relatives. Families may want to consider counseling to help navigate unexpected results.

5. It is also important to consider how your genetic information may be shared once these tests are completed, as these policies may vary by company. Your genetic data, with or without other identifying information, may be placed into private or public datasets, or sold to researchers and other investigators.