Over the counter genetic tests in the UK that assess the risk of cancer or heart problems fail to identify 89% of those in danger of getting killer diseases, a new study has found.
Polygenic risk scores are so unreliable that they also wrongly tell one in 20 people who receive them they will develop a major illness, even though they do not go on to do so.
That is the conclusion of an in-depth review of the performance of polygenic risk scores, which underpin tests on which consumers spend hundreds of pounds.
The findings come amid a boom in the number of companies offering polygenic risk score tests which purport to tell customers how likely they are to get a particular disease.
Everything Genetic promises that their Antegenes cancer test uses hi-tech polygenic risk score technology to assess an individual’s genetic risk of developing cancer.
“The test will tell customers their personalised risk score of developing the cancer tested for over the next 10 years, compared with others in their age bracket,” their website claims.
But the academics at University College London (UCL) who undertook the research are warning that such tests are so flawed they should be regulated “to protect the public from unrealistic expectations” that they will correctly identify their risk of a particular disease.
The authors concluded: “Polygenic risk scores performed poorly in population screening, individual risk prediction and population risk stratification.
“Strong claims about the effect of polygenic risk scores on healthcare seem to be disproportionate to their performance.”
The scores are used to estimate someone’s risk of a disease by analysing whether genes identified through a blood test increase their chances of getting it.
Each gene that may contribute to the development of a disease is given a risk percentage. The risk percentages of all genes present in an individual that may aid the development of a certain disease are then added together to form an overall “polygenic risk score”.
However, Breast Cancer Now defended the tests. They can yield important information when used alongside details of someone’s medical history, for example, the charity said.
“This research shows that polygenic risk score tests alone do not accurately predict breast cancer risk”, said Dr Kotryna Temcinaite, its head of research communications.
“We know many different factors contribute to the chance of developing the disease, including family history and lifestyle. So, when combined with other ways to assess breast cancer risk, this kind of testing can add crucial information and lead to more reliable results.”
The authors, led by Prof Aroon Hingorani of UCL’s institute of cardiovascular science, looked at 926 polygenic risk scores for 310 diseases. They obtained the details from the Polygenic Score Catalog, an open access database.
In highly critical conclusions, they found that on average only 11% of those who developed a disease had been identified by the tests, which also involved a 5% “false positive” rate. The authors found that the risk scores only identified 10% of people who developed breast cancer and 12% of those who developed coronary artery disease, and mistakenly told 5% of people they would fall ill who ultimately did not.
The tests are not as reliable as screening for cancer, for example, they said. “Strong claims have been made about the potential of polygenic risk scores in medicine, but our study shows that this is not justified.
“We found that, when held to the same standards as employed for other tests in medicine, polygenic risk scores performed poorly for prediction and screening across a range of common diseases,” Hingorani said.
Our Future Health, an NHS-backed medical research programme that aims to recruit 5 million participants, is using polygenic risk scores in its quest to identify people’s risk of disease and encourage people to adopt healthier lifestyles.
Dr Raghib Ali, its chief medical officer, said: “This research study rightly highlights that for many health conditions genetic risk scores alone may have limited usefulness, because other factors such as deprivation, lifestyles and environment are also important.
“[Our] research programme will be developing integrated risk scores that will take in all the important risk factors.
“We hope these integrated risk scores can identify people more likely to develop diseases, but this is a relatively new area of science and there are still unanswered questions around it.”
Its 5 million volunteers will help it “discover whether these risk scores have a role to play in giving thousands of people the chance of a longer and healthier life”, Ali added.
