Over-the-counter genetic tests that claim to predict risk of diseases such as cardiovascular disease and cancer miss ‘nine out of ten’

Genetic tests that claim to predict the risk of diseases such as heart disease and cancer miss nine out of 10 cases, a major study has found.

Analysis of polygenic risk scores – which use genetic variations to estimate a person’s likelihood of health problems – found they “performed poorly” in identifying cases.

One in 20 also resulted in a false positive (when someone is wrongly diagnosed with a disease), causing concern and potentially requiring unnecessary testing and treatment.

Negative results can also be “falsely reassuring” to patients, doctors warned.

The commercially available tests are often touted as a breakthrough that could change the prediction and prevention of common diseases.

But in a review of 926 polygenic risk scores for 310 diseases, researchers at University College London found that they typically identified only 11 percent of people who went on to develop a disease.

For breast cancer, they identified only 10 percent of recent cases, along with 12 percent of cases of coronary heart disease, a leading cause of heart attacks and strokes.

At the same time, they mistakenly assumed that 5 percent of people would develop a disease that would not, which could have major health care implications.

Experts have warned that if the tests are used widely – for example as part of a national screening program – it will lead to more false positives than true ones.

Professor Aroon Hingorani, from the UCL Institute of Cardiovascular Science, who led the study, said strong claims had been made about the potential of polygenic risk scores in medicine.

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“Our investigation shows that this is not justified,” he says.

“We found that polygenic risk scores, when held to the same standards as other tests in medicine, perform poorly for predicting and screening for a number of common diseases.”

“Based on the evidence we looked at, we could not see a place for these tests in screening.

“The important thing about many of these conditions, such as heart disease, is that if we have safe and effective preventive treatments such as diet and lifestyle, as well as statins and antihypertensive medications, we can achieve more with their use.” Researchers also investigated how polygenic risk scores would impact if used in addition to traditional screening methods.

They found that, when used in addition to traditional risk factors, several thousand people would need to take a polygenic risk score to guide statin prescriptions and prevent another heart attack or stroke.

Using age alone to prescribe statins would be easier and more effective in preventing heart attacks and strokes without the need for genetic testing, they said.

If these risk scores are added as an initial screening to determine who should be prioritized for mammography, most women who later develop breast cancer will be missed.

According to the findings published in BMJ Medicine, there will also be many false positives, increasing the pressure on health systems.

Co-author Professor Sir Nicholas Wald (UCL Institute of Health Informatics) said: “It has been suggested that polygenic risk scores could be introduced early to prevent breast cancer and heart disease, but in the examples we looked at we found that the case.” found that the results have little or no health benefit, while increasing cost and complexity.”

Available for patients and companies to buy online, Dr Jasmine Gratton from the UCL Institute of Cardiocular Science said polygenic risk scores were becoming increasingly popular.

She said they “seem attractive because genotyping is now cheap, is the same for all diseases and is done only once because a person’s genotype does not change.”

“However, these features are not relevant if the test has no benefit,” she added.

However, Professor Michael Inouye and Assistant Professor Sam Lambert of the University of Cambridge, lead authors of the PGS catalog examined in the study, defended the tests.

They said they have “potential utility in many different cases of clinical use” and that other studies are using the system “in a more flexible way.”

They said: “The current paper generally takes a narrow view of how polygenic scores can be used.”