MIT Technology Review declared 2017 the year that consumer DNA testing ‘blew up’. With pricing at around $60, acquiring one’s personal genetic data has never been more affordable.
Given the easy access to direct-to-consumer (DTC) DNA testing, it is vital to discern the potential value versus possible emotional and physical risks that having such data might present.
According to some industry estimates, over 12 million individuals have participated in DTC DNA testing—and for different reasons. For example: Color is a DTC upstart that solely tests for heritable health issues, such as cancer and heart disease. DTC ancestry DNA testing companies such as AncestryDNA, 23andMe, MyHeritage, FamilyTreeDNA, to name a few, are growing quickly.
Breaking it Down: Genetic Ancestry Testing, Genetic Testing, and Genomic Sequencing
Genetic ancestry testing typically examines these three areas: Y chromosome testing, Mitochondrial DNA testing, and single nucleotide polymorphisms or SNPs. Genealogical DNA tests do not give information about medical conditions or diseases. A deeper explanation can be found here.
An easy way to understand the difference between genetic testing and genomic sequencing is that genetic testing is used to look for inherited mutations in healthy cells, and genomic sequencing is used to look at genetic mutations in unhealthy cells. A NIH primer on genetic testing can be accessed here.
This article was spurred by an impassioned post in STAT by 23andMe founder, Ann Wojcicki, announcing the FDA’s approval of its latest genetic test, focusing on BRCA1 and BRCA2. My view is that Wojcicki’s proclamation that consumers have control over their individual genetic information, and they can easily understand and recognize the results, is a sign of the times. Every day, consumers are gaining more access to, and control of, their health data.
Risks and Downside of DTC Genetic Testing
The FDA’s news release announcing the authorization of the first DTC genetic testing for BRCA1/2 clarified that only three gene mutations comprise the report: specifically, those most common in people of Ashkenazi Jewish descent.
Consumers need to be aware that these three mutations are not the most common BRCA1/2 mutations in the general population. The test only detects three out of more than 1,000 known BReast CAncer susceptibility gene mutations. In other words, a negative result does not exclude the possibility that an individual carries other BRCA mutations that increase cancer risk.
“This test provides information to certain individuals who may be at increased breast, ovarian or prostate cancer risk and who might not otherwise get genetic screening, and is a step forward in the availability of DTC genetic tests. But it has a lot of caveats,” said Donald St. Pierre, acting director of the Office of In Vitro Diagnostics and Radiological Health in the FDA’s Center for Devices and Radiological Health.
St. Pierre went on to say, “While the detection of a BRCA mutation on this test does indicate an increased risk, only a small percentage of Americans carry one of these three mutations and most BRCA mutations that increase an individual’s risk are not detected by this test. The test should not be used as a substitute for seeing your doctor for cancer screenings or counseling on genetic and lifestyle factors that can increase or decrease cancer risk.”
In a recent study published in Genetics In Medicine, the authors stated that “Our analysis indicated 40% of variants in a variety of genes reported in DTC raw data were false positives. In addition, some variants designated with the “increased risk” classification in DTC raw data or by a third-party interpretation service were classified as benign….”
Think about that: four out of ten customers believed they were positive for any one of a number of poor genetic dispositions, until they took the next step to get their DNA tested at a bona fide clinical laboratory.
My Genetic Assay Options in 1991
Well, that would have been zilch.
When I was diagnosed with CLL 27 years ago genetic tests did not exist. The disease was viewed as one condition with no variants, except for the underlying health and age of the host (patient).
The only prognosticator factors were the median life expectancy based on mortality figures for my category of leukemia.
It would be years before cytogenetic testing, including the FISH assay, and Zap70 (confirming a specific protein) were developed. These tests are now used regularly to inform one’s likely course of CLL.
We now know that CLL, like most malignant disease, has several subtypes; the likely course of disease, and treatment approaches, tack closely to these genetic differences.
By the time all of this testing was available to me, my marrow was already cleared of leukemic cells—and without conventional treatment. At that point my chromosomes were normal. (I was originally diagnosed with five pounds of leukemic cells in my spleen, and significant involvement in my bone marrow.)
Had it been available at that time, I feel genetic testing would have been important to me—as an n of 1—in order to have been aware of the critical genetic information at the onset of disease; even if it yielded information that was not yet clinically actionable.
For Me, The Choice is Clear
From my perspective as a forward-leaning, take control n of 1, I want data. Lots of it. All of it. Even if certain data points are not (yet) actionable.
Even if I need to work through false positives that necessitate further clinical testing and waiting. I want to be armed with any and all data that may prove useful in the future.
If the genetic data collection process starts with DTC providers, because more sophisticated clinical testing is not viewed as clinically indicated, and therefore not covered by insurance, I will deal with the angst, anxiety, and waiting that will accompany a false positive reading. Then I will bring the results to my oncologist and have the tests redone (and hopefully covered by insurance).
For All, The Choice Is There and Theirs
It is critical that consumers and healthcare professionals do not use DTC genetic test results alone to determine any treatments, including, in the case of the 23AndMe BRCA1/2 test, anti-hormone therapies or prophylactic removal of the breasts or ovaries.
These treatment decisions require confirmation testing and genetic counseling. And many consumers may opt out of so-called ‘preventive treatment’, because…
Genetics Load The Gun And Lifestyle Pulls The Trigger
For some people who are confirmed to have specific genetic predispositions, such as BRCA1/2 that show increased risk for breast (including men), ovarian, and prostate cancer, the most intelligent ‘proactive actions’ may not necessarily include prophylactic removal of breasts or organs.
Lifestyle and environmental challenges are the major drivers of most cancer. It’s important to remember that genetic predisposition doesn’t mean you will get a particular malignancy. There are many ways we can move that trigger finger away from imminent danger.
Gene expression can be ‘modulated’ through lifestyle. Our genes are being expressed 24/7—all day long. Oncogenes are being switched off and on, based on how we are living.
Cancer epigenetics is the study of inherited changes to molecular processes that influence the flow of information between the DNA of cancer cells and their gene expression patterns.
What we eat, physical activity, stress levels, sleep patterns, all influence gene expression. The medical literature is constantly growing with new contributions from investigators dedicated to studying how lifestyle impacts gene expression.
Here Dr. Dean Ornish shares in Newsweek what he’d already learned a decade ago from his prostate cancer trial, showing the impact of lifestyle to reverse indolent malignant disease.
In summary, while access to DTC genetic testing at a low price helps consumers take control, it vital to understand and keep in perspective these facts:
- DTC allows consumers to learn about their DNA and potential predispositions for certain diseases.
- DTC genetic tests can provide false negatives and positives; be prepared to get follow-up testing from bona fide clinical labs.
- Getting data is wonderful, but we do not yet know how to translate all of this information to the clinical setting in order to best protect or care for patients.
- Follow up with your physician or a genetics counselor for help in understanding DTC genetic test reports.
Having a predisposition for any particular disease does not completely predict your future health situation. Lifestyle decisions influence gene expression and should be wisely leveraged to help prevent disease, and pathology, and conditions of all types.