Ah, the shining promise of at-home genetic testing: spit in a tube and your entire family history will be revealed, mapping out your global genetic makeup, potential future health conditions, and — if you’re lucky — any distant relationship to royalty. (Reader: those chances are slim.)
It’s all fun in theory, but experts have now warned against putting too much faith in the popular technology: we shouldn’t, apparently, be making any health decisions based on these tests.
Writing in the British Medical Journal (BMJ), several researchers from the U.K.’s University of Southampton, Wessex Regional Genetics Laboratory, and the University of Exeter College of Medicine and Health warned that results offered by “direct-to-consumer” (DTC) genetic testing companies, like 23andMe or AncestryDNA, shouldn’t be taken as reliable predictors of health issues.
Watch: Are we giving up our privacy with ancestry tests? Story continues below.
The study, which was published this week, found that all that expensive-looking technology DTC-testing companies use to interpret our genes — your spit in a test tube, for example — are not foolproof, and can sometimes glitch out, showing one result that would be disproven with a follow-up test, or otherwise imply findings that aren’t totally accurate.
Many returning tests, for example, are actually turning up false positive results, and have the potential of convincing recipients that they might be at risk of developing health conditions they aren’t really at risk of developing.
Case in point: in 2016, one couple — a pharmacist and a doctor — bought kits from two such testing companies. The results they got back told them, falsely, that the pharmacist had Lynch syndrome, a genetic condition that gives people over 80 per cent risk of developing colon cancer, as well as a risk of a genetic heart disease that would have increased her risk of arrhythmias and sudden death. (As it turned out, she had neither.)
Similarly, other results are failing to give people the full picture, instilling a false sense of reassurance or security and discouraging them from seeking guidance from an actual doctor, who could give them better insight into their health.
“We recommend that you do not buy these tests, which are at best a waste of money,” Dr. Helen Wallace, director of GeneWatch UK, told BBC News in response to the study.
One of the problems, the researchers found, is that a lot of the nuance it takes to effectively understand someone’s health conditions is lost in the process of at-home genetic testing. Not only are the tests not always up to date, but the data they offer can also be misinterpreted, or illegible to the average person.
Just because a test says you have a genetic variant linked to a disease, for example, doesn’t mean that you have the disease. A doctor would be able to tell you that and provide council, but it isn’t necessarily a conclusion you’d come to on your own, staring anxiously at a document issued through a DTC test.
Still, this criticism, which is not all new, has done little to dissolve their magnetic allure.
Though studies have already confirmed their shortcomings — one such survey found 40 per cent of results were completely inaccurate — it’s been estimated that, by the end of next year, more than 100 million people will have taken the tests.
The conclusion? DTC genetic tests might be fun, but they can’t substitute a trip to a good old fashioned medical professional. In the same way you shouldn’t obsessively Google why your throat feels so dry — unless you want to learn, falsely, that you’re dying — you’re better off seeking out a second, more professional opinion.