DNA Dos and Don’ts

DNA Dos and Don’ts

What you need to know about direct-to-consumer genetic health tests

I stood in front of the bathroom sink, spitting into the tube for what seemed like half an hour, trying to get enough saliva for the at-home genetic test.

The test had been sitting on my desk for several weeks, unopened. I wasn’t sure I wanted to know what genetic mysteries my DNA held. 

I had sent away for the 23andMe genetic test not to find out my ancestry or whether I’m likely to have wet earwax or dry (ew!), but mostly to know whether I had a genetic variant associated with celiac disease. 

My youngest daughter has celiac disease, a genetic autoimmune condition. I always assumed that I must have passed on faulty genes to her (moms always take the blame, but that’s another story), but I had never gotten a genetic test. With at-home tests offering easy accessibility and low prices, I finally decided to jump into the (gene) pool.

Providing context

When direct-to-consumer genetic testing started, it was mostly viewed as ancestry infotainment. But now, companies like 23andMe, Helix and Veritas deliver health information too, such as whether you have genetic variants (previously called genetic mutations) that may indicate you’re at increased risk for conditions such as breast cancer, Parkinson’s disease or cystic fibrosis. 

The testing websites provide screens full of educational information and explanations about the results. While the tests give consumers a wealth of data, some have been criticized for not always being accurate or providing enough context to be medically useful. Because consumers get their genetic information from a computer screen, rather than in dialogue with a doctor or genetic counselor, they might not understand the nuances of their results. Also, the tests for specific variants might not be relevant given an individual’s family medical history. 

“It’s important for patients to be engaged with their healthcare providers to make sure they’re aware of what they’re [testing],” says Peter Hulick, MD, medical director of the Center for Personalized Medicine at NorthShore University HealthSystem. 

Part of the issue is that most direct-to-consumer tests do genotyping — basically spot-checking the DNA in a few places to look for known variants — but not full gene sequencing. 

“Not all direct-to-consumer tests are equal,” Hulick says. “So that’s part of the challenge — knowing what it tests for and what it doesn’t test for. And sometimes that can be tricky to figure out.”

For instance, some of the breast cancer screenings look for three variants in the BRCA1 and BRCA2 genes. If those results come up negative, you might think you are all clear for breast cancer. However, those three variants are common in people of Ashkenazi Jewish descent, but not in most other ethnicities. So while the test may be appropriate for those with Ashkenazi Jewish heritage, it’s less relevant to others. Plus, many other factors, including family medical history and environmental factors like smoking and weight, come into play when determining cancer risk. 

If individuals get the result without genetic counseling, they might not get appropriate medical interpretation and follow-up, says MorrisFiddler, PhD, president of Insight Medical Genetics, a genetic medicine practice in Chicago.

In the case of the three BRCA variations, “[The tests look] at a limited number of possible mutations. When you get a negative result, that doesn’t mean your risk is defined for you in its entirety,” Fiddler says. “Therein lies the potential harm. It’s incomplete information provided without context. In our belief, that information and its meaning should be coming through a discussion with a genetic counselor.” 

Genetic testing needs to be interpreted by a qualified health-care professional in the context of several other factors, such as personal and family medical history.

 

Some services operate differently. With Helix, some tests require physician authorization and include a genetic counseling session. At Color, tests are ordered by a physician — either your own or an independent physician who works with the company — and include genetic counseling. If your doctor orders the test, they will receive a copy of your results. 

Accuracy and privacy

Some questions have been raised about accuracy in direct-to-consumer tests. A small study published in the journal Genetics in Medicine found a 40 percent rate of false positives. The study, which examined 49 patient samples, pointed to some misinterpretations, where the consumer test said a variant increased a patient’s risk of disease but the clinical lab said the variant was benign. 

“While having access to raw genotyping data can be informative and empowering for patients, this type of information can also be inaccurate and misinterpreted,” the researchers say. “Genetic testing needs to be interpreted by a qualified healthcare professional in the context of several other factors, such as personal and family medical history.” 

For greater accuracy, look for genetic health tests that have been FDA approved and that are processed in a CLIA-certified and CAP-accredited lab.

When faced with a screen full of consent agreements, most of us click and sign without reading the releases. But in the case of genetic information, it’s important to know what rights you are granting.

Check disclosures to be sure that if your genetic data is shared with third parties, it is shared in an aggregated, de-identified way.

Your de-identified genetic information might be shared with drug companies or researchers. For instance, pharmaceutical giant GlaxoSmithKline (GSK) has partnered with 23andMe to mine genetic data from its more than 5 million customers to develop drugs, though 23andMe customers need to consent for their data to be used.

Also, while the federal Genetic Information Nondiscrimination Act protects individuals from genetic discrimination in health insurance and employment, there is no such protection for life insurance. So genetic data could be used against you in determining a life insurance policy.

Opening the gates

Direct-to-consumer kits have definitely made genetics more accessible.

“At-home consumer testing has brought genetics more into the mainstream and has started more conversations around it from a patient perspective, which is always a good thing,” Hulick says. 

In the past, genetic counselors have served as gatekeepers to genetic data. But the popularity of these tests shows that people want to open those gates. 

In my case, I was surprised to learn that I don’t have the genetic variants associated with celiac disease. But I learned that I’m at increased risk for age-related macular degeneration. While I haven’t yet discussed these results with my doctor, I do plan to. And for now, I’m thankful that I delved into my DNA.


Originally published in the Spring/Summer 2019 print issue

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