Genetic test kits: what patients deserve to know

Originally marketed as a way to discover ethnic and ancestral heritage, direct-to-consumer (DTC) genetic testing kits have expanded into the areas of predictive health and disease susceptibility. The service, offered by companies like 23andMe and AncestryDNA, is increasingly popular. According to a 2019 study by MIT Technology Review, more than 26 million people had taken tests and consented to the inclusion of their DNA in one of four prominent commercial ancestry and genetics databases. If consumer buy-in continues at this rate, boosted by its usual place atop the gift-giving list this holiday season, the databases could hold the DNA of 100 million people by early 2021.

While testing may seem the prudent choice and accumulation of nearly one-third of the nation's genetic makeup promising from a scientific standpoint, the reality isn't so clear-cut. Patients may consent to these tests for fun, but unearth long-buried and deeply painful family secrets. Other patients who are worried about their health, perhaps on the heels of a relative's unexpected and devastating diagnosis, are frantic to discover any and all genetic abnormalities and may be prone to making rash decisions based on flawed or misconstrued data. Still others have grand plans to "biohack" their physiology in an attempt to achieve optimal health and live well past 100. 

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Regardless of their reasons, it is likely that physicians will encounter mounting questions from patients, test results in hand, who are worried about their risk factors, expecting treatment, further testing or a referral to a geneticist. Here's how to approach these conversations and what patients deserve to know about DTC genetic testing. 

The cost of curiosity  

The ease and affordability of commercial genetic testing kits- typically with no physician order, a noninvasive saliva sample and as little as $99 to screen for several hundred thousand single-nucleotide polymorphisms (SNPs)-has piqued consumer interest, prompting many to view the tests as a sensible way to dive deep into their DNA. Although testing provides pages of information, it doesn't always equate to meaningful or actionable takeaways. 

Dawn Allain, MS, LGC, a licensed genetic counselor and director of the Genetic Counseling Graduate Program at Ohio State University Wexner Medical Center in Columbus, Ohio, completed a kit herself after seeing a substantial increase in patients requesting consultations to discuss their results. "I [wanted to] understand the complete process and have unfettered access to the [same] services the company provided to individuals," says Allain. 

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Her findings were more entertaining than groundbreaking. The test accurately identified her ethnicity and that she was unlikely to have dimples, a cleft chin, and a fear of public speaking-all traits easily verifiable without DNA sampling. Although the testing disclosed that she is a carrier of a common gene variant associated with hereditary hemochromatosis, it wasn't particularly relevant to her own health going forward. "I am only a carrier and not at risk for the disease," says Allain. "Given this is a common condition in the general population, knowing I am a carrier allows for risk assessment for my children and sister." According to the Centers for Disease Control and Prevention (CDC), most people with hereditary hemochromatosis never develop symptoms or complications, so even if someone has the condition identified via testing, modifications in current medical management or lifestyle are not always useful.  

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The ensuing "curse of knowledge" can be devastating for patients with genes that are correlated to illness or disease, even if they are unlikely to ever suffer any ill effects. Physicians should caution patients about the emotional and psychological repercussions and remind them that correlation does not equal causation. "[Patients] learn about the probability of developing various conditions, which is usually low in terms of absolute risk, even if [their] risk relative to the rest of the population is high," says Talya Miron-Shatz, PhD, a researcher specializing in social psychology and founding director of the Center for Medical Decision-Making at Ono Academic College in Israel. "[W]hatever information you learn, you cannot unlearn. Every person should ask themselves whether they want to live their healthy years in fear of a condition which may not erupt." 

Unfortunately, the rising consumer interest in genetic testing has led to a market awash with options, little oversight, and gross oversimplification of a complicated topic. "There are many predatory genetic services available today that promise things like an idealized diet for weight loss or risk [quantification] for health conditions that genetic counseling could assess from personal and family history," says Nicole Umberger, PhD, a geneticist and technical director of Molecular Pathology at LifeBrite Laboratories in Atlanta, Ga. "There are hundreds of complex traits. For many, it's not a simple 'yes-no' answer." She recommends physicians check in with patients and make sure they are not purchasing unnecessary products and services that have little added value. 

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The danger of false negatives of positives

Despite the Food and Drug Administration (FDA) authorizing the marketing of 23andMe's Personal Genome Service Genetic Health Risk (GHR) tests, which look for particular SNPs commonly found in late-onset Alzheimer's, hereditary hemochromatosis and eight other conditions, the agency has warned that DTC tests should not be used for diagnostic or treatment purposes due to the potential for false negatives and positives. 

When false negatives occur and test results seem otherwise unremarkable, patients can be lulled into a sense of security and feel almost genetically invincible, leading to less compliance for existing treatment plans and self-care regimens. It's imperative that physicians have a candid discussion with patients about the validity and scope of DTC testing and establish realistic expectations. "While DNA test kit companies have done good work raising awareness of genetics, it's not going to tell you your predispositions to diseases," says Theodora Ross, MD, PhD, a board-certified oncologist and director of Cancer Genetics at University of Texas Southwestern Medical Center in Dallas. "[DTC] tests rely on self-reporting. As we know from Dr. House, everybody lies, so the databases are less validated compared to clinical data. The kits are more incomplete than a clinical test [and] false negatives are very common. The results should be taken not with a grain of salt, but a big bag."

Ross, who underwent prophylactic double mastectomy and bilateral salpingo-oophorectomy following clinical confirmation of her risk for breast and ovarian cancers, says that even a negative result provided by licensed geneticists isn't a golden ticket. Future advances in testing methods are probable, for which patients would need to undergo additional screenings to obtain more accurate results. "We ask our patients to remember that genetic testing is a process, not an event, and to check in with us every year just like some people check in with their financial counselor or primary doctor," Ross says. 

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False positives come with their own risks and are not rare occurrences either. According to a 2018 Genetics in Medicine study, false positives account for up to 40 percent of gene variants reported in DTC raw data. This becomes more problematic as third-party interpretation services like Promethease and GEDmatch gain popularity, allowing users to upload raw data and generate customized reports about potential disease-associated SNPs not otherwise included in standard DTC summaries. Users must agree that the service is for educational and research purposes only, but there's virtually no way to verify that the results are accurate or interpreted correctly. 

Experts say physicians should encourage patients to share their reasons for seeking genetic screening as well as any results already obtained from commercial kits. "It could be that the individual is concerned about something in their personal or family history and would benefit from a referral to a genetic professional," says Allain. "There may be individuals who have results that they do not understand and may be misinterpreting their risks."

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This was the case for one of Ross' colleagues, a fellow physician who initially feared he had Lynch Syndrome based upon raw data findings. He eventually found his way to Ross and a clinical test confirmed it was a false positive. The trauma of such an event cannot be overstated as it is can create significant psychological stress and pursuit of costly and invasive testing and interventions. 

Testing as a conversation starter 

A patient's interest in genetic testing can serve as leverage for physicians to deepen engagement, fully address concerns and tweak treatment plans. Jada Moore-Ruffin, MD, FAAFP, ABOM-BC, a board-certified family medicine physician specializing in nonsurgical weight loss and integrative wellness in Atlanta, Ga., uses it as a conversational jumping off point.  

"It's important to listen carefully to what's keeping them up at night and address their concerns without falling into the 'testing trap,'" says Moore-Ruffin. "I often explain that these tests are better for some things than others and we will use these results along with a careful personal and family history to create a preventive health plan." While Moore-Ruffin utilizes specialty SNP DNA analyses in her practice, she acknowledges the face-to-face review of results as well as the detailed recommendations she provides are instrumental in ensuring the testing is used responsibly and effectively. 

There are additional upsides to pursuing testing under the guidance of a physician or geneticist, especially for patients who have limited access to family history. "[It] makes sense for a person with no idea of their family history (i.e. adopted, estranged, or small family) who could use genetic testing as a starting point to build a health profile," says Umberger. Genetic profiling can be beneficial in optimizing some drug therapies, a process called pharmacogenetics, or for couples planning to conceive, though determinations must still be made on a case-by-case basis.  

Healthy habits for the win

If at-home testing identifies certain highly predictive SNPs such as those associated with pancreatic or breast cancers, then more frequent screenings may be advised following confirmation via clinical testing and a geneticist consultation. For many patients, findings can be instrumental in spurring healthful behavior. "[F]or the patient who leads a sedentary lifestyle or smokes, knowing that they specifically have an increased risk for cardiovascular disease or diabetes may be the one thing that convinces them to change their behaviors where previous counseling has not been effective," says Moore-Ruffin. 

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Ultimately, the mere presence of a SNP doesn't automatically translate to disease. Environmental and lifestyle factors affect gene expression, essentially turning on or off the signals that launch a physiological cascade toward dysfunction. The goal, most experts agree, is to postpone or stop that switch from flipping in the first place. Practicing healthy habits can go a long way toward negating patients' predispositions. "There is no genetic testing, to my knowledge, that would alter my recommendation for healthy eating, exercising, smoking cessation and limiting alcohol," says Ross. 

Steph Weber is an award-winning freelance journalist hailing from the Midwest. She writes about healthcare, human resources and small business.