A world-first pilot of predictive genetic testing aiming to identify those at high risk of cardiovascular disease is under way in GP surgeries in the north of England.
The NHS pilot, called Heart, is offering genetic tests to 1,000 healthy volunteers aged between 45 and 64 years old to give more accurate predictions for their risk of heart disease and stroke.
The pilot could be the first step towards a wider rollout of predictive genetic testing on the NHS to improve screening for those at risk of a range of common diseases including breast and bowel cancer, diabetes and osteoporosis.
Prof Sir Peter Donnelly, the founder and chief executive of Genomics, the company that developed the tests, said: “These are people going about their daily lives who are at high risk of cardiovascular disease who are currently invisible to the NHS. We can find these people who are actually at quite high levels of risk but not aware of it.”
Genetics is an important risk factor for many common diseases, including heart disease. However, until recently it has been impossible to quantify the genetic component of risk because it is typically spread thinly over thousands of DNA regions. The advent of vast genetic databases has changed this, allowing scientists to develop algorithms that aggregate the contributions of huge numbers of genes into a “polygenic risk score” (PRS) for a given condition.
The participants will be recruited from those undergoing a routine NHS health check that is offered to people over 40. As part of the check, GPs use an algorithm called QRisk that combines non-genetic factors such as age, blood pressure, smoking history and cholesterol to identify those at risk. Those estimated to have a 10% chance of a heart attack or stroke in the next 10 years are advised on lifestyle changes and offered medications such as statins.
The pilot will combine the QRisk score with the genetic score to provide a more precise estimate of risk. Research suggests that in 45- to 55-year-old men, the PRS is the single most important risk factor, explaining about the same amount of the risk for heart disease as the combined effect of all the non-genetic risk factors. Overall, about 5% of people aged 45-65 are expected to be above the risk threshold for statins based on PRS and QRisk combined, but not on Qrisk alone. Applied to the number of 45-65-year-olds in England, if these extra individuals were all treated with statins about 9,500 cardiovascular events could be avoided over 10 years.
Michael Brennan, 61, who is retired and lives in Darlington, said he had no hesitation in signing up for the pilot. “I’m probably not alone at this time of the year in thinking about health and lifestyle,” he said. He is waiting his results, but said he will be glad to find out either way. “If I know, I’ve got a chance of doing something about it,” he said.
However, some have concerns that deploying the tests could lead to “genetic fatalism”, because unlike most other risk factors, genetic ones are not modifiable. There is also continued concern that the tests, which have been largely developed using genetic data from white Europeans, give less accurate results for people from other ethnic backgrounds. Donnelly said that the company had “worked hard” to address this issue that genetic ancestry is factored in when calculating risk scores.
However, Prof David Curtis, a geneticist and psychiatrist at University College London, said that it had not been demonstrated that the tests work equally well for those of all backgrounds. “I maintain that this is a test that will work less well in people with minority ancestries and so would be expected to increase inequalities in healthcare,” he said.
Prof Ahmet Fuat, the chief investigator on the pilot and a GP with a specialist interest in cardiovascular health, said genetic testing could be a “game changer” for primary care. “Genomic testing can improve our identification of patients who need extra management, screening or treatment, and better personalise those interventions to them,” he said. “Common diseases like cardiovascular disease place a great deal of demand on our resources and anything that helps us use those more efficiently and effectively is incredibly valuable.”
