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.

Just Posted

University of Victoria tells stories of Holocaust survivors with graphic novels

International storytelling initiative launched first meetings this winter

Vancouver Island artist’s mask heading to prestigious U.S. museum

John and Peggy Varnedoe purchased the piece and have donated it to the Burke Museum in Seattle.

Island astronomer discusses search for life in oceans of moons of Jupiter and Saturn

University of Victoria’s Jon Willis says where there’s salt water, there could be life

Untrending: Maybe it’s time to define success on your own terms

Take a closer look at how to set and achieve your goals

Morris Moss: ‘One of the most colourful figures this coast has ever seen’

So one historian termed the handsome Jewish pioneer whose life was more exciting than fiction

Officials reaching out to those in contact with Canada’s first coronavirus patient

The illness has sickened at least 1,975 people and killed 56 in China

Kobe Bryant killed in California helicopter crash: reports

NBA star was reportedly in his private helicopter at the time of the crash

Investigation launched after six dead puppies dumped in Richmond hotel parking lot

RAPS reminds people they can always give up puppies they can’t take care of

Risk of coronavirus low in B.C. as first case emerges in Toronto: officials

There have been no confirmed cases of the virus in B.C.

‘Presumptive case’ of coronavirus in Canada confirmed by Ontario doctors

Man in his 50s felt ill on his return to Canada from Wuhan, China

VIDEO: Drone footage shows extent of damage in Highway 4 rockslide

Tofino, Ucluelet still cut off from rest of the island, as crews work to repair roadway

People knowingly take fentanyl so make policy changes to reduce harm: B.C. study

Dr. Jane Buxton, an epidemiologist at the centre, says drug users need more resources,

‘My heart is going to bleed’: Bodies brought back to Canada following Iran plane crash

Remains of Sahar Haghjoo, 37, and her eight-year-old daughter, Elsa Jadidi, were identified last weekend

Most Read