An example of a DNA collection test used at Any Lab Test Now on Friday, July 20, 2018 in Everett, Wa. (Olivia Vanni / The Herald)

DNA tests make fun holiday gifts, but beware of the hype

Whether interested in your health or your ancestors, it is important to understand how these tests work

You’ve likely heard about direct-to-consumer DNA testing kits. In the past few years, at-home genetic testing has been featured in the lyrics of chart-topping songs, and has helped police solve decades-old cold cases, including identifying the Golden State Killer in California.

Even if you don’t find a DNA testing kit under your own Christmas tree, there’s a good chance someone you know will.

Whether you’re motivated to learn about your health or where your ancestors came from, it is important to understand how these tests work — before you spit in the tube.

While exciting, there are things that these genetic testing kits cannot tell users — and important personal implications that consumers should consider.

Health, traits and ancestry kits

My main area of research is around clinical genome sequencing, where we look through all of a person’s DNA to help diagnose diseases. With a PhD in genetics, I often get questions from friends and family about which direct-to-consumer genetic test they should buy, or requests to discuss results. Most questions are about two types of products: ancestry and health kits.

The most popular ancestry kit is from AncestryDNA. These kits are aimed at giving users insight into where their ancestors might be from. They can also connect users with family members who have used the service and have opted into having their information shared. Another option is Living DNA, which has a smaller dataset but provides more precise information on the U.K. and Ireland.

The most popular health kit is from 23andMe. Depending on the user’s preference, results include information on predispositions for diseases such as diabetes and Alzheimer’s, as well as on the likelihood of having certain traits such as hair colour and taste. This company also offers ancestry analysis, as well as ancestry and trait-only kits that don’t provide health information. The kit offered by the newer MyHeritage DNA also provides a combined ancestry and health option.

There are other kits out there claiming to evaluate everything from athletic potential to relationship compatibility. But gift-buyers beware: for most of these, in contrast to those above, the evidence is seriously lacking.

How these tests work

For all of these tests, customers receive a kit in the mail. The kits contain instructions for collecting a saliva sample, which you mail back to the company for analysis.

During this analysis, these popular tests do not look at the entire genome. Instead, they employ single nucleotide polymorphism (SNP) genotyping. As humans we all share 99.9 per cent of our DNA. SNPs are essentially what is left: all of the points at which we can differ from our neighbour, making us unique. SNP genotyping looks at a subset of these sites to “survey” the user’s genome.

These SNPs are then compared to reference datasets of individuals with known conditions or ancestry. Most results are based on the SNPs shared with a given group. For example, if your results say that you are 42 per cent Southeast Asian, it’s because 42 per cent of your SNPs were most likely to have come from a group in the reference dataset labelled “Southeast Asian.” The same goes for traits and health conditions.

How they differ from clinical tests

Direct-to-consumer genetic tests are not a substitute for clinical assessment. The methods used differ dramatically from what is done to diagnose genetic diseases.

In a clinical setting, when suspicion of a genetic condition is high, entire genes are often analyzed. These are genes where we understand how changes in the DNA cause cellular changes that can cause the disease. Furthermore, clinical assessment includes genetic counselling that is often key to understanding results.

In contrast, findings from direct-to-consumer genetic tests are often just statistical links; there is commonly no direct disease-causing effect from the SNPs.

Users may interpret a result as positive, when the risk increase is only minimal, or entirely false. These tests can also give false reassurance because they do not sequence genes in their entirety and can miss potentially harmful variants.

Before you spit in a tube, stop and think

These tests are exciting: they introduce new audiences to genetics and get people thinking about their health. They’re also helping to build vast genetic databases from which medical research will be conducted.

But for individual users, there are important caveats to consider. Recent reports have questioned the accuracy of these tests: identical twins can receive different results. Furthermore, a lack of diversity in the reference data has caused particular concern regarding accuracy of results for ethnic minorities.

There are also concerns about the way these tests emphasize racial categories that science considers to be social constructs and biologically meaningless.

Professor Tim Caulfield shares concerns about the way race is presented in the marketing of DNA tests.

A recent paper in the British Medical Journal suggests four helpful questions for users to consider. First, users should ask themselves why they want the test. If it is to answer a medical question, then they should speak with their doctor. Users should also think about how they might feel when they receive results containing information they would rather not know.

Users should also consider issues around security and privacy. It is important to read the fine print of the service you’re using, and determine whether you’re comfortable sharing personal information, now and in the future.

In Canada, policies around genetics have not always kept up with the science. At present, direct-to-consumer genetic testing is unregulated. And, although Canadians have legislative protections against genetic discrimination, those laws are being challenged in the courts, and could change.

Finally, it may also be worth discussing DNA testing with relatives. We share half of our genome with our immediate family members, and smaller fractions with more distant relatives. Genetic results not only affect us, but our family.

Bottom line: It’s all for fun

Some users may feel they learn more about themselves. For others, results may bring people closer together — not a bad outcome for the holiday season.

At the end of the day, these genetic testing kits are for entertainment: they should not be used to assess health risk in any meaningful way.

If you have any questions related to your health or a genetic disease, discuss these with your family doctor or a suitable health-care professional.

Michael Mackley, Junior Fellow, MacEachen Institute for Public Policy and Governance; Medical Student, Dalhousie University , The Canadian Press

Like us on Facebook and follow us on Twitter.

Get local stories you won't find anywhere else right to your inbox.
Sign up here

Just Posted

WATCH: Eckville man’s hobby creates wild backyard snow park

Dolan Baxter has been building snow parks ranging of all styles since he was a kid

UPDATE: Sylvan Lake RCMP say missing female located

19-year-old Alyssa Manderville was last seen in Blackfalds on Jan. 26

Long-term solution being explored for frost heaves between Sylvan Lake and Red Deer

Alberta Transportation has completed two repairs to the two kilometre stretch of road

Eckville Fire Department responds to four structure fires in 2019

Fire Chief Stuart Carde says the department received a total of 42 calls last year

Death Cafes set to make Eckville debut

The four sessions in February will focus on making the most of your life through discussion and tea

VIDEO: Feds look to help 126 Canadians quarantined in China for coronavirus

China has confirmed more than 4,500 cases of the new virus, with more than 100 deaths

Air Canada cancels select flights to China as coronavirus spreads

Canada’s largest airline runs 33 flights a week to China

Canadians seek way out of Wuhan as coronavirus continues to spread

The Chinese government has cut off access to Wuhan and 16 other cities

Landowner hearings begin for Trans Mountain expansion in Alberta

Detailed route talks start in Spruce Grove, in B.C. communities soon

Ryan Jake Applegarth, 27, charged with First Degree Murder

RCMP Major Crimes Unit seeking male wanted on first degree murder charge

Watch out for scams, clickbait in the wake of Kobe Bryant’s death: Better Business Bureau

Kobe Bryant and his daughter were killed in a helicopter crash near Los Angeles

Despite reports of decline, birds flocking to national parks in Canadian Rockies

Recent studies suggest overall bird population has slid by three billion since 1970

Pregnant B.C. woman stuck in Wuhan, the epicentre of coronavirus outbreak

Woman is due to give birth in Wuhan, China unless she can get out

Majority of Canadian boards had no female members in 2016 and 2017: StatCan

Statistics Canada says 18.1 per cent of director seats were held by women in 2017

Most Read