DIY testing kits identify gene variants wrongly 2 times in 5

At-home genetic test results should be verified by medical professionals, researchers have warned, as a study reveals that 40 percent of the time DIY testing kits incorrectly identify genetic variants.

The DIY genetic testing industry has exploded in recent years. The market for testing is currently worth nearly £70 million annually, predicted to triple by 2022. But the accuracy of these tests is remarkably low, say the authors of a study published in Genetics in Medicine. 

Full diagnostic-grade laboratory tests on 49 study participants' samples showed that the DIY kits were wrong two times in five, according to the paper. The participants were people who had done a test at home and then sought medical advice and confirmation after getting their results. 

'Such a high rate of false positives in this particular study was unexpected,' said Stephany Leigh Tandy-Connor of Ambry Genetics, who led the study. 'While direct-to-consumer test results may lead to healthy changes in lifestyle or diet, these could also result in unwarranted emotions, including anxiety when someone obtains unexpected information, inaccurate information or disappointment.'

The study was small, but it is the first to measure the discrepancy between DIY genetic testing kits and lab-based diagnostic tests. Some of the shortcomings of the tests could be because they are often interpreted by medical staff who have limited knowledge of genetics, Tandy-Connor said. 

DIY genetic test kits commonly claim to be able to predict whether someone is at risk of certain genetic conditions or how they will react to certain drugs, as well as people's ancestry. The tests are regulated by the  Food and Drug Administration in the US and the Medicines & Healthcare Products Regulatory Agency in UK, and only some are licensed for diagnostic purposes. 

However, some companies also provide the raw data from the tests to customers, which can contain information reported as 'secondary findings'. These may include genetic variants strongly associated with conditions that pose a significant risk of morbidity and mortality. Although many test providers do not vouch for the accuracy of their raw data, they still provide it to customers on request. 

Patients can then choose data can be sent to third-party organisations for further analysis, usually for a fee. Patients' doctors can also order the raw data for analysis while assessing patients who have reported their DIY test results to them. 

It was this data that was found to have the high error rate, when analysed by the diagnostics laboratory Ambry Genetics and compared with full diagnostic tests on the patients' samples. In addition, third-party companies that had been commissioned to interpret the data gave misleading results to patients in eight cases, the study found. 

Most people who use at-home testing kits do not seek confirmation from their doctors, said Tandy-Connor. 'People may assume that they are being provided accurate medical-grade testing, so understandably do not go to the trouble and expense of seeking confirmation.'

The inaccuracy and misinterpretation of the raw data pose substantial risks to people who obtain the raw data from their DIY test kit provider, the researchers concluded.