get to know you – The Varsity

An ever-growing list of companies such as 23andMe and Ancestry.com offer the general public the opportunity to get to know each other by testing their DNA and commenting on the results.

The ad is familiar to the demanding viewers of American television: a young woman travels the world while a blanket of Broadway air "Getting to Know You" plays in the background.

Useful pop-ups indicate the ethnic makeup of the actress as she crosses the landscapes; "29% East Asian" flashes under the neon lights of a metropolis, "3% Scandinavian" appears among the glaciers.

The announcement ends with the tantalizing offer that you could, too, discover what makes you right by sending a saliva sample to 23andMe.

These advertisements are indicative of a thriving industry.

But the self-knowledge they sell to consumers is no longer limited to an individual's past.

The latest trend in personalized genomics lies in its predictive potential: predicting the probability of an individual developing diseases such as cancer, diabetes and other diseases to which a person may be genetically predisposed.

How do genetic tests work?

According to Dr. Stephen Scherer, a professor of medicine and director of the McLaughlin Center at the University of Toronto and the Applied Genomics Center at Sick Kids Hospital, the tests include a microarray – microscope slides printed with thousands of tiny dots in defined positions – with a mixture of genetic markers or DNA sequences with known physical locations on chromosomes.

According to the companies, each test contains about one million genetic markers.

"They then analyze a saliva-derived DNA sample sent in a DNA sputum kit," Scherer writes in an email to The Varsity. "They make laboratory changes to the DNA and place it on the microarray and test the presence or absence of a given genetic marker, and then use that information to predict the medical outcome.

"They use information from large-scale published studies where they provide an estimated risk of disease development for some genetic variants," wrote Dr. Ryan Yuen, an assistant professor of molecular genetics, in an email to The Varsity. "These companies will then report the estimated risk for these variants if they are also detected in the subject."

Yuen also explained how similar methods are used to determine the ancestry of an individual: "They compare the genetic variants detected in the subject with many other sequenced individuals (both internally and externally) . The more genotypes are similar between individuals, the more likely they are to be related to each other.

Scherer explained that findings regarding common diseases such as heart disease, hypertension or diabetes are derived from statistical probabilities and that nothing is definitive.

"For some rare genetic mutations that predict a medical outcome (such as cystic fibrosis), the ability to predict risk is much higher," Scherer wrote.

So, what is the reliability of these tests?

A cardinal rule of observational data is that correlation does not necessarily imply causality and therefore the reliability of genetic testing is debatable.

"While these tests may seem exciting, it's important for consumers to be aware and understand the limitations of these types of tests," said Salma Shickh, a Certified Genetic Consultant, who is pursuing a PhD in genomics. in an email to The Varsity.

"Most of these tests only cover … specific regions of the DNA code and, therefore, the risk they provide may not be based on complete information," explained Shickh. "These tests are often offered without proper education and advice for patients, which is important because they give consumers information about their health."

Scherer echoed Shickh's feelings. Scherer said it was important for consumers to realize that results are being achieved in the labs and that companies that sell genetic tests must generate a profit margin by analyzing many samples at once.

As a result, the results are usually, but not always, accurate. In other words, consumers must interpret the results with a grain of salt.

"We believe that testing is useful if genetic counselors interpret the data to help doctors and families understand what it means, and just as importantly, what it does not mean. Most companies do not use genetic counselors, they just send you the data, "Scherer wrote. "If you do this type of test, ask for genetic counseling to help interpret the results."

What is the future of genetic testing?

Although genetic testing is not perfect, Scherer noted that their value should not be discounted.

"[The tests today are] generally not much better than knowing your family history, but as the data compares, it should get better and better, "Scherer wrote.

"Today, I'm comparing the terrain to the early days of GPS units. As more and more cards were put online (and then on Google maps), predictability continued to improve. "

Tags: Genomics Consumers, Genetics, SickKids, Applied Genomics Center, McLaughlin Center of the University of Toronto