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What Secrets Can Genetic Tests Really Reveal?

dna illustration

Dec. 27, 2018 -- When Joshua Cohen learned at 10 years old that he had been conceived through a sperm donor and his dad was not his biological father, he hid under his bed and cried. “I felt like a part of my identity was suddenly in question,” says Cohen, now 40.

For nearly 30 years, Cohen wondered who his biological father was. “It was always the great mystery of my life.” All he knew was the city where the sperm donation came from -- the donor had been a medical resident at a hospital there -- and that his mother had requested a Jewish donor.

Throughout his 20s and 30s, Cohen searched online for male doctors who had completed their residency in the late 1970s in the city where his mother had received the sperm donation. He zeroed in on those with typically Jewish surnames and tried to find their photos online. “But none of them quite seemed to match my face.”

In 2016, Cohen heard a story about a man like him, who never knew his biological father and found him through 23andMe, a mail-order, or direct-to-consumer DNA test. “That’s why I decided to do it,” Cohen says. “I spit in a tube, dropped it in the mail, and waited for my results.”

23andMe is one of at least a couple dozen companies that market DNA tests you can order on your own to get information you would have had to request from a health care provider just a decade ago. Cohen’s test gave him information about his risk of getting certain diseases; an estimated breakdown of his ethnic makeup; and -- the part he was most interested in -- a social platform where he could connect with people who may be related to him because they share DNA. Most of the big competitors -- Ancestry DNA, My Heritage, National Geographic -- offer one or more of those features.

In a few weeks, Cohen’s results were on the company’s website. They included an analysis of his DNA for genetic variations, or differences, that might raise his risk for diseases including Alzheimer’s, Parkinson’s, and breast cancer. Before customers can get to their results, they must go through educational modules to make sure they understand the information they could receive.

Though Cohen had ordered the test to find his biological father, he realized the health part made him nervous.

“I had my husband, Kit, look at the health section first to see if there was anything in there that I wouldn’t want to know,” he says. “I didn’t have any of the gene variants they tested for at the time, so that was a big relief.”

Experts warn that people should be neither too relieved nor too alarmed about their health results in these one-size-fits-all tests. The test for Parkinson’s risk, for example, doesn’t look for all of the more than 41 DNA variations associated with the disease. What’s more, if Cohen had a variation in his DNA, his risk of disease would vary based on his ethnicity, which variation he has, and many things about his lifestyle.

“Who knows how many people are out there living with the belief that they have some devastating genetic variant when they actually don’t,” says Brianne Kirkpatrick, a licensed and certified genetic counselor in Crozet, VA.

But, according to 23andMe, the vast majority of customers can understand the information they receive on their own. The company had to prove that to get FDA approval of the tests. “As part of the FDA review process, we conducted comprehensive user testing across a wide demographic -- age, sex, education, ethnicity -- and were able to demonstrate more than 90% comprehension of the genetic concepts conveyed in our reports,” says a company spokesperson.

The test for breast cancer risk, while less of a concern for men, is also far from thorough. 23andMe’s educational module explains that more than 1,000 variations in the BRCA1 and BRCA2 genes could raise the odds of having breast cancer. 23andMe tests for three of those variants, which are most common in Ashkenazi Jewish people.

Testing positive for one of the three variants in BRCA1 and BRCA2 does not provide enough information, for example, to show whether you should start mammograms earlier and have them more often. If you had a strong family history of breast cancer, for example, your doctor would more likely order a test that looked for the gene variant that runs in your family.

If you’re interested in your health information, particularly if you have a strong family history of a certain disease, a doctor or genetic counselor can point you toward the best test for you. If you’ve already done a test on your own, or have your heart set on trying it out, understand that the health information is not a diagnosis and offers limited risk information.

“It’s only the first step in the process,” says Kirkpatrick. Results from these tests require confirmation. “Taking the next step, to see a doctor or genetic counselor, can cost extra and leave you in a period of limbo, where you don’t know for some time whether to be worried or not.”

Some testing companies, such as Color, Veritas, and Helix, attempt to bridge that gap between the traditional method of ordering tests through your doctor and the direct approach. You choose the test online, and a doctor who works with the company physically orders that test.

“Because a physician is ordering the test, it’s not subject to the same FDA regulations as the strictly direct-to-consumer tests are,” says Robert Green, a medical geneticist at Brigham and Women’s Hospital and Harvard Medical School in Boston. “But it’s not just a regulatory workaround. In some cases, the doctor raises smart questions about your family history and the appropriateness of this particular test versus a different test.” The companies that use the doctors market their tests as tools that patients can use with their doctors to guide their care.

Ethnicities from Around the World

Besides offering health information, some direct-to-consumer companies use science to make their best guess as to where your ancestors came from. They do this by comparing your DNA to “reference” DNA known to come from people with a generations-long history in a certain place, such as Finland or Nigeria. Companies that offer ethnicity testing provide charts that show what percentage of your DNA is similar to that of people from regions around the world.

That’s how Cohen discovered that the hospital had not honored his mother’s request for a Jewish donor. His test showed that he was only half Jewish. He got that part from his mother. As for the rest, he says, “I’m about 20% British, 8% French and German, some Southern European, and about 4.5% Lebanese. Maybe the Lebanese is where my coloring came from,” he says of his olive complexion. 

For Cohen, learning about his health and that unknown half of his genetic makeup meant a lot. “I was crossing my fingers that I’d find out more than that, but this was interesting enough.”

But there was more.

DNA Relatives You Never Knew

One of the most popular features of direct-to-consumer genetic tests is a social media platform that connects people with relatives -- other customers in the database who share bits of identical DNA. On average, your siblings and parents share about 50% of your DNA. Half-siblings, aunts, uncles, nieces, and nephews share about 25%. First cousins share about 12.5% of your DNA. Fourth cousins share .2%. The service attracts adoptees, donor-conceived children, and others who hope to find unknown relatives.

Hands trembling, Cohen waited until after he’d reviewed all the other portions of his profile, then he clicked on his DNA relatives. “At the top of my list was an anonymous person, and it said ‘predicted half-sister.’”

Because she was anonymous, Cohen didn’t imagine he’d ever learn anything about her, but he took a chance and sent her a message through the website. He told her the few bits of information he had about his biological father and asked if she knew more. By now, it was the middle of the night. He closed his computer and went to bed.

“When I woke up, she had already written back,” he says.

Deb was an American living in the Middle East. Born and raised in the United States, she had no idea that her dad (a doctor) had ever donated sperm, but she asked him and it was true. After exchanging several emails with Cohen, Deb broke the news to him: Her dad had no interest in meeting him. “He said it was just a donation,” Cohen said. “He never expected to hear from anyone, and there were between three and 10 others like me out there.”

Cohen had prepared himself for the chance that the mail-order test could lead him to a father who didn’t want to meet him. “I was expecting that. And I expected it to feel terrible, but it really didn’t. Having a picture of him, knowing his name, and having a connection with [my half-sister] felt like a lot.”

A few months later, Deb flew to New York. Cohen, his husband, and their 2-year-old daughter drove to Manhattan from their home in Germantown to meet her. “As soon as she got in the car, she started to cry,” Cohen recalls. “She said she didn’t expect me to look so much like her dad.”

They spent the day together, getting to know each other, learning about everything they had in common. “She said to me, ‘You’re the brother I’ve always wanted.’ ”

What to Know About Raw Data

Some direct-to-consumer genetic tests include access to your raw data -- a downloadable document containing a long list of letters and numbers that represent your genetic code. You don’t need to do anything with this document, but here’s what some people do:

  • Upload to third-party sites, such as GEDmatch and DNA.Land, to find more relatives than those available in your testing company’s database.
  • Upload to third-party sites, such as Promethease, Xcode Life, and Genetic Genie, to learn what scientific research says about the health risks that your specific gene variants may pose.

Before you proceed, understand a few things:

  • Third-party sites are open platforms that lack the same privacy policies and rules that govern the big companies. Read terms of use carefully.
  • Sites that interpret what your genetic makeup may mean for your health only match your genes to those found in a database of scientific literature. The analyses are only as good as the site’s most recent research update, and they are notorious for false positives.
WebMD Health News Reviewed by Brunilda Nazario, MD on December 27, 2018
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