What are the potential harms?
These tests can vary in reliability and the validity of their interpretations is not universally accepted. What can be labelled a ‘problem’ or ‘risk’ or ‘disease’ may in fact not be accurate or may not apply. As data emerges, these risk scores can change. We have seen patients inaccurately portray their results as a disease when it is not. Thinking incorrectly that one has a ‘bad’ gene can actually lead to bad health outcomes. In one study, people who were told they have a bad exercise gene actually performed worse in repeat testing, when in fact they didn’t have that gene. The power of the mind is often stronger than a lot of these genes. Contrary to most SNPs tested, some gene variations have a strong penetrance, meaning if you have it, you do have a strong risk of serious disease. People need to be ready to hear this information and likely should have access to a health professional to go over the data and not be facing a screen alone with bad news.
In Canada, law prohibits any person from requiring an individual to undergo a genetic test or to disclose the existing results of a genetic test. It is also prohibited to collect someone else’s genetic material without their consent. At present, this appears to protect us from discrimination, or discriminatory rulings, against our genetic material. Keep in mind, however, if you discuss your genetic results with your physician and that note gets entered into their record, their record can often be requested by third parties. Many of the direct to consumer DNA testing kits offer lengthy explanations about how they take privacy seriously, which of course is excellent. However, in the era of common data breaches, there may be cause for concern. For businesses, there is also a lot of value in collecting large amounts of genetic data, and this data is often sold to other companies for research purposes. Just be aware of this when sending in your DNA samples. You could have your genetic information shared with unknown others.
Should I get this test done?
We are in the era of precision medicine. Data holds potential and knowledge is powerful. So while a lot of these DNA tests aren’t likely as predictive as we had hoped, they can offer clues and be motivating in the right setting. As doctors, we do see significant value in these gene tests as it relates to potential adverse drug events. As mentioned, certain genes penetrate stronger into our physiology and can be deterministic; certain breast cancer genes, certain colon cancer genes, some Alzheimer’s genes, and some longevity genes, for example. In reality, most disease is polygenic—involving multiple genes—and hugely impacted by environment (ie. how we live our lives, what we eat, how we sleep, how handle stress, and how often and with what intensity we move). The totality of these influences is difficult to measure and quantify. The other reality is most strong genetic traits are better learned from understanding your family history. We often don’t dig deep enough here. We might argue about whether a certain gene or cluster of genes will result in early disease. But if you have a family history of very early breast cancer or heart attacks or even many thriving 90-year-olds in your family, then this is important. The bottom line is: it’s rare that information from these genetic tests will alter our practices and recommendations. They simply do not tell you your fate. But, they do offer some insights, and if you can accept most interpretations with a grain of salt, then they can be entertaining and perhaps you will learn a few things about your ancestry. —LP