While direct-to-consumer (DTC) genetic testing companies like 23andMe and Ancestry can be fun ways to obtain clues about your ancestry, common traits, and health, there are some things you should know before purchasing one of these tests. 

What is DTC testing?

Let’s start by defining DTC genetic testing. Most of the time, genetic testing is done through a health care provider. However, with DTC genetic testing, genetic test kits can be purchased directly by the consumer online or from a store. Once the test kit is obtained, the consumer provides a saliva sample and mails the test kit to the company from which the kit was purchased.  

DTC genetic tests are available for a variety of traits, diseases, conditions and have a varying level of reliability, validity, clinical utility, and claims made about them. I like to divide DTC tests into four categories.

In contrast to whole genome sequencing, which cost about $1000-$4000 and look at all the genes in your genome, DTC tests cost about $99-$199 and assess only a very small portion of your genome. This is done by looking at Single Nucleotide Polymorphisms (SNPs), which are relatively common variants in the genetic code that many people carry. 

It can be difficult to interpret genetic test results. In fact, The American College of Medical Genetics (ACMG), recommends that “because of the complexity of genetic information and the challenge of interpretation, genetic testing should not be accessed without qualified health professionals.” The data supports this statement. Many studies, including those of my own research, have indicated that individuals do not adequately or accurately understand what their genetic test results mean for themselves or their family members. In non-DTC testing, a health provider will determine which test is needed, order the test, collect and send a DNA sample, interpret the test results, and share them with the patient. Often times, genetic counselors are involved pre- and/or post-genetic test. Pre-test, a genetic counselor might explain the pros and cons of genetic testing, the type of information a particular genetic test will yield, and what the information yielded from a genetic test will mean for individuals and their family members. Post-test, a genetic counselor might help individuals to understand what their result means, answer questions, think through possible actions or interventions that may reduce the risk or severity or a certain disease or condition, and asess whether and what family members are at-risk. 

Is it really that important to think and talk about all this stuff before and after having genetic testing? It’s really not that big of a deal, right?

Consider two examples. The first example is a man who receives genetic test results indicating a mutation known to be associated with hereditary colon cancer. Even though this man does not currently have colon cancer, he is at increased risk for developing colon cancer during his lifetime. It is important for this man to understand what his result means for both himself and his family members, because taking the appropriate actions could have significant implications on his own health and the health of his family members. The man should speak to his doctor about this genetic test result because it may be appropriate for him to begin colonoscopies at a younger age, or have colonoscopies more frequently, than is routinely recommended for people with an average lifetime risk of colon cancer. It is also important for the man to inform his at-risk family members about his result, because they are at-risk of carrying this same mutation. His family members may then decide whether they wish to speak to their doctor about the test result, pursue genetic testing, and take similar actions with preventative screening (if appropriate). Both the lives and health of the man and his family members could be improved, and/or extended by early detection and prevention of colon cancer

Consider a second example in which a woman is at-risk for Huntington’s Disease (HD), a neurodegenerative disease for which there is no cure or treatment available. Unlike most genetic test results, results indicating one carries the disease-causing mutation in HD mean that the individual will, with certainty, develop HD. A woman who is presymptomatically tested (tested before she has any symptoms) is at risk of severe depression, substance abuse, and even suicide if she learns she carries the disease-causing mutation for HD. However, finding out she has the mutation may also have positive effects, including reducing anxiety about the uncertainty of whether or not she will develop the disease and about life decisions, including financial planning, having children, traveling before versus after retirement, etc. The HD community is very divided on whether to pursue presymptomatic testing for HD. While some individuals find it beneficial to know their gene mutation status to reduce uncertainty and increase their ability to plan for the future, others adamantly wish not to know their gene mutation status. Though DTC genetic testing for HD is not available and must be done through a health provider, this example illustrates the importance of carefully and thoughtfully considering whether and how results from a genetic test might benefit or harm you, and what you will do with that information, before pursuing testing. 

The caveats of genetic risk estimates

Another complication of interpreting DTC genetic test results is that many DTC tests are genetic risk estimates for diseases and conditions. Genetic risk estimates do not tell you if, when, or how severely you will develop a disease or condition. However, risk estimates for diseases and conditions involve not only genetic, but also environmental risk factors.  For example, your genes are not the only thing that influences your chances of getting skin cancer — UV exposure also plays a role. Additionally, most diseases and conditions found on DTC tests are polygenic, meaning that there is not simply one gene associated with a disease or condition, there are many. We do not know with certainty all the variants associated with most diseases and conditions because the field of genetics and genomics is constantly evolving. We are continuing to discover different variants that are, and are not, associated with diseases and conditions. Furthermore, the tests that are available often do assess all of the variants currently known to be associated with a disease or condition. 

Did you know that insurance companies can use genetic information to exclude you from their policies?

A final consideration of DTC testing is data privacy. Some DTC genetic testing companies use your genetic data for internal research, allow external companies and institutions to use your genetic data for research, and/or sell your genetic data to third parties. While many companies claim they “de-indentify” your genetic data before using or selling it, de-identifying genetic data is impossible — it’s the most personalized information that exists. The Genetic Information Nondiscrimination Act (GINA) of 2008 prevents employers and health insurance companies from discriminating against individuals on the basis of genetic information, but GINA has some gaps. It does not cover members of the military, and it does not protect against genetic discrimination for long term care insurance or life insurance. Many insurance companies explicitly ask if you’ve had genetic testing. If you have had any type of genetic testing (including DTC or clinical testing) you must report this to the insurance company, so keep this in mind. 

While the potential harms of DTC testing have undoubtedly been the focus of this post so far, there are also potential benefits that should be mentioned. Benefits include opportunities to be more informed about your disease risk, seek medical advice, and engage in lifestyle changes or preventative interventions that may increase the quality and duration of your life. See the table below for more pros and cons of DTC testing.

Only you can decide whether or not DTC testing is right for you. The intention of this post is not to tell you whether or not to pursue DTC testing, but rather to help you be an informed consumer by offering information about DTC testing. 

Stay informed & curious,

K