Author: Tina Hesman Saey / Source: Science News
Results from Family Tree DNA, a genetic testing company, helped Lara Diamond find a branch of her family she thought had been lost in the Holocaust.
Those 2012 results brought dozens of new people into her life.Eager to find more relatives, Diamond, now 42, a professional genealogist in Baltimore, decided to try out all the companies that offer geneaological DNA testing to see what else she could learn. Results from one of them, 23andMe, hit her with an entirely different kind of life-changing knowledge: a high risk for breast cancer.
Browsing through the health and trait reports the company provides, Diamond reached the locked reports, which contain information about genetic variants that increase risk for developing breast cancer, Alzheimer’s disease or Parkinson’s. Customers have to choose to “unlock” that information since it can bring upsetting news.
Diamond considered her family history. “Because we have Alzheimer’s and Parkinson’s in my family, I said, ‘OK, I’ll think about those. But we don’t have breast cancer, so I’ll open this BRCA thing,’ ” she says, referring to the family of genes linked to breast cancer.
To her shock, Diamond learned she has a variant in her DNA that alters one amino acid in the BRCA2 protein, putting her at high risk for the disease. “One little stupid mutation. One amino acid. And it changes your whole life.”
The next morning she called her doctor, who sent her to a genetic counselor. The counselor ordered a confirming DNA test from a lab certified to do medical diagnostic testing. Diamond also got a mammogram, an MRI, an ultrasound and blood work to screen for breast, ovarian and pancreatic cancers, because her variant boosts risk for all three. The MRI revealed a tiny spot of cancer deep in her breast, too small for the mammogram to detect. She decided to have a double mastectomy.
This feature launches a multipart series on consumer genetic testing. See the whole series.
Her doctors are urging her to have her ovaries and fallopian tubes removed as well, to head off ovarian cancer. “I’m not ready to do that yet,” Diamond says.
Diamond had been mostly interested in what her genes could reveal about her family history, not the health information they hold. But millions of genetic testing customers want to know their medical future. Even though most consumer genetic testing companies collect data on thousands of gene variants that may have an impact on health, companies such as 23andMe are allowed to give only limited information about genetic health risks. The companies’ reports focus mainly on ancestry or basic physical traits (SN: 5/26/18, p. 20).
So the marketplace has devised a work-around: Consumers who want to know about their risks for diabetes or several other diseases can turn to third-party services to analyze the raw DNA results generated by testing companies. New research suggests, however, that some of the answers people find through these third-party services are wrong and could prevent people from listening to their doctors or genetic counselors. That is, if the person bothers to go see one.
The market responds
Diamond got her health-related results in 2013, just before the U.S. Food and Drug Administration told 23andMe to stop giving consumers health information. The company had to demonstrate to the FDA that the information it provides is accurate and communicated in an easy-to-understand way. In 2017, 23andMe won approval to slowly add back reports for certain health conditions.
Most recently, in March, the FDA granted approval for the company to tell customers if they have one of three genetic variants in the BRCA1 and BRCA2 genes. Those three variants are responsible for about 74 percent of inherited breast cancers among people of Ashkenazi Jewish heritage. Less than 0.1 percent of people of other ethnicities carry these variants.
Offering information on only three variants, when there are thousands in the two genes that increase risk for breast and ovarian cancers — as well as melanoma, prostate and pancreatic cancers — is troublesome, say health care providers, breast cancer advocacy groups and others.
With only a partial list of variants called out, test takers who don’t carry one of those variants may misinterpret the results, worries Lisa Schlager, vice president of community affairs and public policy for FORCE, a hereditary breast cancer information and support group.
People who don’t carry one of the variants may say, “I don’t have a genetic risk that predisposes me to cancer. I’m safe,” Schlager says. “But that is absolutely not correct; you are only negative for three out of thousands of possible mutations. So our concern is that the public is not going to understand the limitations.”
Yet Schlager and others admit that allowing companies like 23andMe to provide FDA-approved information and explain the results — however incomplete — may be the lesser of two evils.
“There’s a sort of underworld that’s been going on since the FDA stopped 23andMe from interpreting these results and giving them out to people,” Schlager says. For a small fee, third-party analysis services stand eager to offer the interpretation that testing companies choose not to provide, or aren’t allowed to provide under FDA rules. These services include Promethease, an early player in the consumer raw data analysis market, along with Genetic Genie, LiveWello and many, many others.
That’s possible because customers of direct-to-consumer DNA testing services such as 23andMe, AncestryDNA and Family Tree DNA can download their raw DNA data to send to third-party analysis sites or apps. Those raw data consist of a list of spots, known as SNPs (pronounced “snips”), where customers’ DNA varies. Some third-party analysis services will also look at a wider swath of information, data on protein-coding regions, called the exome. Genos is one testing company that provides raw data on the exome.
Helix, a testing company that provides “exome plus” data, has partner apps that customers can buy to analyze limited sets of their data. (Or, for $499, you can download all of your raw data). So far, very few of the third-party analysis services are set up to process data from the entire genetic instruction book, or genome.
To write their reports, Promethease and the others find scientific studies that mention the genetic variants a customer carries and make inferences about the health risks of carrying those variants. “That has been…
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