Genetic testing is no longer a rarity. Once only ordered by doctors, genetic tests are now more accessible and affordable than ever before. It’s not uncommon to know someone who has recently given – or received – a DNA testing kit as gift.
And it’s no wonder. The sheer number of testing kits available directly to consumers has grown like wildfire in recent years. The most well-known among them is 23andMe, which offers a health and ancestry saliva-based DNA test for about $200. Other companies selling similar products include Helix (and its Mayo Clinic GeneGuide product), Vitagene, Orig3n, Futura Genetics, HomeDNA, 24Genetics, EasyDNA, and more.
Most of these businesses claim to tell you whether you have genetic markers for a wide variety of diseases and medical conditions – as many as 200 different conditions with a single test.
Sure, the kits are convenient, relatively cheap, and make a fun gift. But is the disease-screening on offer accurate? Could it do more harm than good?
Accuracy of Genetic Health Screening
According to Dr. Harry J. Thomas, a board-certified gastroenterologist at Austin Gastroenterology in Bailey Square, St. David’s Plaza, and Westlake, Texas, genetic test results as they apply to disease risk should be interpreted with caution – especially the at-home variety.
Take celiac disease, for example, a common autoimmune disorder. For people with celiac disease, eating gluten (a protein found in wheat, barley, and rye) causes inflammation that, over time, can damage the small intestine.
“The genes being tested for in celiac disease are HLA-DQ2 and HLA-DQ8 and approximately 30 percent of the American population has those genes without having the disease,” Dr. Thomas notes.
So, genetic test results – at least as it pertains to disease screening – are not definitive, and often additional triggers must be present before a particular disease is likely to develop.
“Celiac disease is a complex disorder and many other factors, including many we don’t know about, come into play,” Dr. Thomas explains. Of course, gluten exposure is involved, but other possible triggers may include viral infections, the makeup of your own personal microbiome (the balance of microorganisms in your gut), and more.
Test results can be quite complicated, and take an emotional toll. Often, when consumers receive their test results, they end up scrolling through page after page of a voluminous report indicating, among other things, which diseases or medical conditions they may be predisposed to get or may be a carrier for. But receiving so much granular information can be emotionally overwhelming and meaningless, in practical terms, for the average person.
Then, too, there are inaccuracies of the human-error sort to consider. Accuracy of at-home DNA testing can be a concern, Dr. Thomas points out, because the tests rely on samples collected at home and then mailed in – and any number of things can go awry along the way to degrade the sample and throw off the results.
“An NP who works for us had a cancer scare after doing one of those tests,” he says. “But the formal testing she received from a doctor actually negated the results of the at-home test.”
Dr. Thomas advises patients to take these test results with a grain of salt.
What Do I Do With My 23andMe Health Risk Results?
Ideally, genetic disease-risk results should be used to help guide a discussion with your doctor, not necessarily as definitive proof that a certain medical condition is likely or inevitable. Nor should it be taken for granted that every patient with a certain genetic marker need undergo additional, sometimes costly, testing.
“For patients with concerns about gluten intolerance or celiac disease, seeing a gastroenterologist rather than a genetic counselor is preferable,” Dr. Thomas says. You’ll need a gut specialist, he explains, to help you interpret and assess your DNA report results and to proceed with the appropriate next steps, especially if additional diagnostic testing is needed.
Next steps will depend on patient symptoms.
For example, an endoscopy of the small intestine and tissue biopsy to gauge the damage to the small intestine may not be necessary for a patient with relatively minor GI symptoms. In many cases, a blood test looking for antibodies to celiac disease can lead to a diagnosis. Treatment options may remain diet-based for the vast majority of patients with concerns about celiac disease.
Gastrointestinal Disease Screening
Dr. Thomas, who has a special interest in GI conditions such as Crohn’s disease and ulcerative colitis, as you might expect, says that nothing can replace regular visits with your doctor, especially if you have risk factors for certain conditions.
When it comes to colon cancer, for example, nothing can surpass the effectiveness of colonoscopies to screen for the earliest signs of this most preventable of diseases. Anyone 50 or older or who has a family history of colon cancer, should contact their gastroenterologist to schedule a colonoscopy – something Austin Gastroenterology is interested in getting the word out, especially since it’s Colon Cancer Awareness Month.
For other conditions, Dr. Thomas recommends follow-up with a medical professional. Patients who receive their 23andMe results that indicate a genetic marker for celiac disease, for example, should see their GI doctor.
And there’s no one like your doctor who can best advise you on the lifestyle or other changes that are within your control, to lessen the likelihood of disease. Get health care personalized for you, in the form of in-person care with a medical professional – not cookie-cutter lab results that are difficult to interpret, at best.
Know Your GI Risks
Whether you’ve tried at-home genetic testing or not, if you’re concerned about whether you’re at risk for a particular disease – especially celiac disease, colon cancer, or any other gastrointestinal disorder – contact the GI pros at Austin Gastroenterology. The only way to be sure is to consult board-certified physicians who can walk you through what your risks may be, and whether additional screening is necessary for you. Contact us at the location nearest you; we have 18 offices located throughout central Texas.