With direct-to-consumer (DTC) genetic tests like 23andMe becoming increasingly prevalent, physicians must prepare themselves to discuss such tests with patients. Though these tests are growing in popularity, their efficacy is still in question and there are several confounding variables that can skew results. When patient’s come to their physician with results from these DTC tests, it is imperative these providers are well informed of the test’s implications.
“The genetic testing offered by companies like 23andMe and most direct-to-consumer testing is not medically useful, and patients should not think they are getting genetic testing that will help with their medical management,” Dr. Wendy K. Chung from Columbia University, New York, NY, told Reuters.
The FDA warned that such testing could be flawed and actually shut down several companies providing these tests. 23andMe is currently authorized to sell genetic tests for 10 conditions and 3 specific pathogenic variants in BRCA1/BRCA2 genes, which are commonly linked to breast and ovarian cancers.
Information Provided by DTC Tests
The implications of DTC testing vary across the company providing the service. Some companies only provide genetic ancestry information, such as National Geographic and AncestryDNA. Others provide more information with the approval of a health care professional. Among these companies are Genos, providing full sequencing of the protein coding genome, and Veritas, giving detailed genetic risk data. 23andMe, on the other hand, is a consumer test that gives genetic health risk data without involvement of a physician.
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An investigation conducted by the US Government Accountability Office in 2006 found that many DTC companies were providing false advertisement. The FDA warned of these tests threatening individual safety, and forced 23andMe and several other DTC testing companies to discontinue their operations. In 2015, 23andMe was allowed to resume business after providing sufficient evidence that the consumer audience was able to comprehend these results appropriately, and the company has continued to add variant’s to their testing since. Though the FDA allowed 23andMe to resume as a risk assessment test rather than a diagnostic tests, many consumers cannot differentiate between the two.
Shortcomings of DTC Tests
DTC genetic tests offer convenient genetic testing to the consumer in that it is easily accessible, affordable, and can reach those with poor insurance coverage. It should be noted, however, that these DTCs are not diagnostic and only offer information regarding a limited number of diseases and genes. In addition, their accuracy and validity has been brought into question when analyzing risk profiles for consumers.
Many of the conditions 23andMe tests for are very rare as well. Though they may increase risk, the variants included in the test usually account for a small proportion of the genetic variants contributing to a certain disease. In addition, none of the genes analyzed via 23andMe are fully sequenced or assessed, therefore diagnostic data is limited. With many variants being modified by the environment, one’s lifestyle, and other genetic sequences, the positive result for many of these conditions is not a strong indicator.
Emphasizing these few genetic variants with no family disease history or medical records can yield inaccurate predictions of disease risks and test results. Particularly, poor readings of test results are common in consumers who are not of European descent, being that the tests don’t include variants common in minority populations. The 23andMe tests are, however, more accurate in variants commonly found in those of Ashkenazi Jewish descent.
Given this data regarding DTC test results, consumers should have their results solidified through a clinical diagnostic laboratory and should always seek clarity with an educated physician. With use of DTC genetic tests on the rise, it is imperative that clinicians are prepared to discuss results with their patients and that the general public becomes better educated on the implications of such tests.
If you’re looking for a solid, balanced review of direct-to-consumer #genomics—and how these tests can be used clinicians—here it is: https://t.co/3uVJda4oO2 by @kirylukk and colleagues @ColumbiaMed @23andMe pic.twitter.com/tS9g6XoEGn
— Eric Topol (@EricTopol) April 30, 2019
Sources: Annals of Internal Medicine, MDLinx