Healthy Living

Genetic testing for health risks: What you will and won't learn

A 23andMe Inc. DNA genetic testing kit in Oakland, Calif., on June 8, 2018. MUST CREDIT: Bloomberg photo by Cayce Clifford.
A 23andMe Inc. DNA genetic testing kit in Oakland, Calif., on June 8, 2018. MUST CREDIT: Bloomberg photo by Cayce Clifford.

If you thought that ordering a 23andme test might resolve your worries about developing cancer or another serious health condition, think again.

Even as “direct-to-consumer” genetic testing grows, and our knowledge base increases about many diseases, most tests are still providing only limited information — not enough for people to self-diagnose or know on their own how to proceed.

Over-the-counter genetic testing should never be used in isolation of professional guidance to make medical care decisions, said Colleen Campbell, director of genetic counseling operations for the University of Iowa Hospitals and Clinics in Iowa City.

“It is critical that consumers not change their medical management without speaking to their health care provider first,” Campbell said. “Results of direct-to-consumer tests need to be interpreted with caution. These products do not test for all causes of a health condition, and any health risks findings should be retested in a medical setting.”

Bryant McAllister, a University of Iowa biology professor, holds a monthly discussion group on genetic testing to help people sort through the growing pile of questions surrounding the field.

Modern-day news developments like Elizabeth Warren’s reliance on 23andMe for her personal ethnicity can lead to spikes in genetic testing, experts say. Driving home caution in direct-to-consumer genetic testing became especially important after 2013, when Angelina Jolie announced that genetic testing had played a key role in her decision to have both breasts removed.

Often lost in high-profile news stories are the fine details, say McAllister, Campbell, and other experts. For example, Jolie’s decision was based on a full sequencing of her BRCA 1 and BRCA 2 genes.

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“That was much more extensive than what 23andme tests,” McAllister said. “23andme only reports on a limited number of variants for an increased risk of hereditary breast cancer. And only those found in Ashkenazi Jewish people.”

The same applies for tests regarding conditions like Alzheimer’s, McAllister said. “That’s another good example of how DNA testing can be misconstrued. 23andme reports on one variant. Alzheimer’s is tied to hundreds of variants.”

McAllister describes himself as an “outlier:” a researcher who supports the public’s overall access to genetic testing and the ongoing data it provides. But even he is concerned that the public may misinterpret the information they now can glean from the thousand or so “direct-to- consumer” genetic tests like 23andme or Color.

“I’m of the camp that knowledge is power. And so I do think that we should be able to access this kind of information about ourselves,” McAllister said. “But I do have concerns that people are not correctly interpreting, or may be overinterpreting, the information they’re getting. Right now, these tests are only screening for a small portion of the variants that underlie the incidence of disease.”

Most studies show that the public isn’t rushing out to chase unnecessary medical procedures because of the overall increase in genetic testing availability, McAllister said.

The greater concern, he said, is the opposite: that people may have a false sense of security when interpreting and applying the test results. Especially when it comes to breast cancer, McAllister said it’s essential to keep family history as the top criteria in approaching prevention and treatment.

“The concern is those with a familial history of breast cancer would get their tests back and decide that they do not have an elevated risk based on the test’s results,” he said. “Do they take actions to decrease their motivation to do mammography? That would be a misinformed action because of the limited nature of the test and its ability to screen your genetic risk.”

Genetic counselors and medical professionals have specialized training to carefully interpret genetic testing results and recognize their limitations. But people who are trying to interpret their own results may be affected by untold variables, said Anya Prince, an assistant professor of law at the University of Iowa.

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“23andme has tried to make it clear the limitations of the testing they provide,” she said. “But the question is whether it’s clear enough for people who might read their results while they are on the phone, or who may be busy, or who don’t have as much health literacy.”

While widespread testing helps generate more genetic information overall, it also muddies the world of testing in a way, Prince said. “We don’t really know who should have gotten which types of tests,” she said.

Conversely, some research suggests that fear of genetic discrimination leads many to avoid genetic testing, Prince said. Employer “wellness programs” are one way that genetic information can be used to essentially transfer the cost of medical care from employers to employees, she notes.

“It’s a theme of promise versus perils. In the cancer space, we have all this promise where if we figure out who has predispositions to cancers, we really can save lives,” Prince said. “But that excitement is being moved into society in a lot of different ways, that I think we need to make sure we’re looking at the social, ethical and legal impacts of that.”

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