Direct to Consumer Genetic Testing: Think Before You Spit, 2017 Edition!

April 18, 2017 by Muin J Khoury, Director, Office of Public Health Genomics, Centers for Disease Control and Prevention

test tubes and DNA

As people have become more proactive in managing their health, personal genomic direct to consumer (DTC) testing has become more popular over the past decade. These tests allow consumers to access information about genetic predispositions and response to chemicals and medications without the involvement of healthcare providers. With the expanding landscape of such testing, the need for provider education and public genetic literacy has become more important than ever.

Typically, these tests use DNA derived from saliva to measure hundreds of thousands of genetic variants and provide individualized reports on genetic predispositions to common conditions, such as Alzheimer’s disease, celiac disease and Parkinson’s disease. Some tests also include information on carrier state for rare genetic conditions such as hereditary hemochromatosis and hereditary thrombophilia.

Although personal genomic tests for disease susceptibilities could help to make decisions about lifestyle choices or inform discussions with providers, they are not diagnostic tests, and cannot be used alone for treatment decisions or other medical interventions (in contrast, for example, to BRCA gene testing for hereditary breast and ovarian cancer).

The pros and cons of personal genomic DTC tests have been discussed for years (see recent example .) We have adopted a cautionary attitude about personal genomic tests. In 2011, we advised consumers to think critically about the health utility of these types of tests, as well as the potential harms and unnecessary follow-up health care costs that could result from testing. In our three-tiered evidence classification of genomic tests, we include personal genomic tests as “tier 3” tests. Such a rating implies that there is no evidence for clinical validity or utility of such applications in healthy individuals in the population. In 2009, on the basis of a scientific workshop , we called for additional research to evaluate the validity and utility of personal genomic tests to improve health and prevent disease. Over the past few years, some of that research has been conducted and published. For the most part, data on personal genomic testing have revealed little or no harms but also little or no health benefits. Also, evidence on the ability of genetic information to change health behavior has been lacking.

With improved technology and plummeting prices in the coming decade, we could see an expansion of DTC testing for personal genomic information. The content of information obtained from such testing will evolve. Nevertheless, both the general public and the health care provider community need to be aware of the potential utility and limitations of such tests. In a 2016 study , a survey of people who underwent personal genomic tests found that most of those tested who shared results with their health care providers were not satisfied by the reaction of their providers. Many providers questioned medical actionability of the test results and showed lack of engagement or interest. In a recent commentary in Nature, Dr Zak Kohane from Harvard University stated that when it comes to personal genomic tests, “we really have a perfect storm of insufficient data and insufficient competence.” Physicians aren’t yet prepared to handle genetic test results of this type and neither is the general public.

While evidence of utility of personal genomic information continues to be collected through ongoing research studies, it is important for professional societies, healthcare organizations, public health agencies and the private sector to improve the level of genomic health literacy of the public. We all need unbiased information to be empowered to make the most informed decisions about genomic and other tests for our own health. Our advice, in 2017, remains the same as in 2011, namely for consumers to think before they spit and rush to do DNA personal genomic testing (see our previous blogs: 2011,2012 and 2016).

We have recently initiated a community conversation about the appropriate role of genetic screening in healthy adults (see our recent blog). We invite our readers to share their thoughts and opinions.

April 18, 2017 by Muin J Khoury, Director, Office of Public Health Genomics, Centers for Disease Control and Prevention