AV俱乐部 the author:聽 is a medical student at AV俱乐部 and a junior fellow with the MacEachen Institute for Public Policy and Governance.
You鈥檝e likely heard about . 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 .
Even if you don鈥檛 find a DNA testing kit under your own Christmas tree, there鈥檚 a good chance someone you know will.
Whether you鈥檙e motivated to learn about your health or where your ancestors came from, it is important to understand how these tests work 鈥� before you spit in the tube.
While exciting, there are things that these genetic testing kits cannot tell users 鈥� 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鈥檚 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 . 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 , which has a smaller dataset but provides more precise information on the U.K. and Ireland.
The most . Depending on the user鈥檚 preference, results include information on predispositions for diseases such as diabetes and Alzheimer鈥檚, 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鈥檛 provide health information. The kit offered by the newer also provides a combined ancestry and health option.
There are other kits out there claiming to evaluate everything from to . 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 . As humans . 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 鈥渟urvey鈥� the user鈥檚 genome.
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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鈥檚 because 42 per cent of your SNPs were most likely to have come from a group in the reference dataset labelled 鈥淪outheast Asian.鈥� 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 .
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.
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Users may interpret a result as positive, when the . These tests can also give false reassurance because they do not sequence genes in their entirety and .
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鈥檙e also helping to build vast genetic databases from which .
But for individual users, there are important caveats to consider. Recent reports have questioned the accuracy of these tests: . Furthermore, has caused particular concern regarding accuracy of results for ethnic minorities.
There are also concerns about the way these tests .
A 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 .
Users should also consider . It is important to read the fine print of the service you鈥檙e using, and determine whether you鈥檙e comfortable sharing personal information, now and in the future.
In Canada, policies around genetics have not always kept up with the science. At present, . And, although Canadians have , those laws are being , 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鈥檚 all for fun
Some users may feel they learn more about themselves. For others, results may bring people closer together 鈥� 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.
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