At Home Genetic Testing Can Confuse Heritage with Heredity

By Jeanne Homer, M.S.

Categories: Featured News , Cancer
October 26, 2018

For $199 and a tube of saliva, I found out that I have straight hair and green eyes. Mirrors have been telling me this my whole life for free. But as a genetics counselor, I wanted to learn more about the recreational home genetics tests that have been captivating people.

What I was left with (aside from the aforementioned physical description and unsurprising heritage data), was the sense that the dangers of taking direct-to-consumer genetic information seriously are manifold.

For one, recreational genetic testing companies are private; and we have seen time and again that private companies, such as Facebook, are not always the most vigilant custodians of our personal data. Also, the results might uncover hidden, painful family secrets that were hidden for a reason.

Most importantly, however, are the health implications. There is a significant difference between tracking down your ancient Scottish heritage and mining your genetic material for predisposition to disease.

Genetic testing can be an incredibly empowering tool in your personal health toolkit, but it has to be wielded correctly.

In a recent study, clinical genetic testing laboratory Ambry Genetics discovered that 40% of variants in a variety of genes reported in direct-to-consumer genetic tests were false positives – meaning a lot of people were likely told they were at “increased risk” of diseases erroneously.

These results are not surprising. Too often, I have people in my office who falsely believe they are at increased risk for cancer because a mail-order test gave them the wrong information. More worrying, however, are the cases where people’s gut-feelings are wrongly assuaged.

For example, the FDA has recently granted 23andMe authorization to provide genetic information on three genetic variants found on the BRCA1 and BRCA2 genes, which are known to be associated with higher risk for breast, ovarian and prostate cancer. What people don’t realize is that those are three areas out of thousands – and they are primarily useful for only 2% of Americans.

I have had women in my office who told me they believed that their commercial genetics tests cleared them of a BRCA mutation – only to find out through the more thorough and rigorous testing by a clinical lab, that they did, in fact, have an increased hereditary risk. In this case, the difference between relying on a commercial test and a clinical one could be the difference between life and death.

What’s more, these women paid upward of $250 for incomplete tests, whereas tests performed through genetic counselors at hospitals like Hoag are covered by insurance for those with a family history of certain breast and ovarian cancers.

The other problem with using recreational genetic tests for medical purposes is that no medical professional would accept the raw data or summarized results. The direct-to-consumer labs simply don’t have the same level of quality and quality control that clinical labs require. As a case in point, a genetic counselor famously sent one of these companies a DNA swab of a Labrador retriever and received a detailed report back about the “person’s” medical health. (Incidentally, the dog also has straight hair.)

While I am grateful that companies like 23andMe are raising awareness of genetic testing, I caution people to remember that not only is the information unreliable from a clinical perspective, it is incomplete.

Genetics are only a piece of the puzzle. Family history, lifestyle and many other factors combine to influence your health. A genetic counselor can answer all your questions and provide a lifetime source of support.

I am a strong believer in the power of genetic testing to empower people to be proactive about their health. But before you delve into your DNA, be sure to seek out a well-trained genetics team. One that knows the difference between a dog and a human, and one that can help you learn more about yourself than a mirror could have told you.

Jeanne Homer, M.S., is coordinator of the Hoag Hereditary Cancer Program.