The swab means that nurses can identify whether a premature baby would be genetically predisposed to being left deaf after treatment with gentamicin, a life-saving antibiotic used to treat 90,000 newborns a year. Guidelines say a baby should have gentamicin administered within an hour, though researchers have known for 25 years that the antibiotic could lead to deafness caused by a genetic variant which affects 1 in 500 people. Testing for it has traditionally taken days.
But now, in just 20 minutes a nurse working alone can establish, by placing cells from a baby’s cheek swab into a into a PC-sized molecular-diagnostic bedside machine, whether their infant patient has the genetic variant which rules out using gentamicin – and if so to prescribe an alternative drug instead.
The test, which already has Health Research Authority, CE and ethical approval, has just started trials in neonatal intensive care units at St Mary’s Hospital, Manchester, part of Manchester University NHS Foundation Trust, and Liverpool Women’s Hospital. Used across the NHS, it could save more than 180 babies a year from going deaf as a result of gentamicin.
Bill Newman, professor of Translational Genomic Medicine at the University of Manchester and consultant at Manchester University NHS Foundation Trust, who is leading the trial, says that the technology could be used in future to identify how patients are affected by other drugs.
Mr Newman – whose team includes the developers of the testing equipment genedrive plc and parents of children treated in NICUs – said: “Successful implementation of the gentamicin test will be a first in the integration of a rapid decision-making, genetic-based diagnostic in the UK NHS. It opens the door to getting much better outcomes for a number of other diseases too now that the test is out there.”
In addition to saving families from the emotional anguish of a diagnosis of profound deafness, the success of the Pharmacogenetics to Avoid Loss of Hearing (PALoH) study will save the NHS an estimated £5m every year (including the cost of the test) in cochlear implantations and other hospital costs, according to health economists making up part of the team.
The Genedrive test costs around £60 per baby at the moment and was developed by the Manchester-based medical equipment company genedrive plc, in collaboration with Mr Newman’s team. The development research took place at Manchester Biomedical Research Centre with £900,000 in funding from the National Institute for Health Research (NIHR) and support from the charity Action on Hearing Loss.
Mr Newman is convinced that the successful implementation of this trial will open the door to early detection of more common conditions. His team is already working with genedrive plc on a similar rapid bedside test for stroke patients – to detect the one in 10 patients whose DNA makes them unable to metabolise clopidogrel, the common anti-platelet medication, and therefore have significantly worse outcomes.
Models suggest similar tests could prevent several thousand of the 100,000 strokes suffered by people each year in the UK. It also opens up the possibility of using pharmacogenetics testing more widely by using biomarkers to target treatments more appropriately.
Mr Newman said: “It raises the long term possibility of developing a series of tests which might be given to everyone at the age of maybe 40 or 50 (when people start to develop health problems) to look at various genes that we know to be linked to specific drug outcomes. Health passports linked to electronic patient records might then be developed that contain information such as ‘codeine does not work for this patient’.”
If the PALoH trial is successful, it could be rolled out across the NHS within a year, under National Institute for Health and Care Excellence (Nice) guidance. There is also interest in the bedside test from Australia, the USA, Israel and the Netherlands.
Health secretary Matt Hancock recently revealed ambitious plans for the NHS to introduce a form of DNA testing called “whole exome sequencing” for a range of inherited conditions at birth, to reduce their impact. It has currently been tried on 80 babies, and can provide a diagnosis in days rather than weeks.
Gentamacin-induced deafness: Darren’s story
When Darren Emson woke up in intensive care in Warrington and Halton hospital in 2002 after three weeks in a coma, he realised he had lost his hearing and could neither speak nor even lift up a pen.
“I felt trapped inside myself,” says Mr Emson, now 49 and able to hear with a cochlear implant. He later learned that he had suffered a road accident in which he had escaped with minor injuries, only to develop a life-threatening abdominal infection and multiple organ failure as a result of seat belt injuries. As his life hung in the balance, the medical team fighting to save him gave him gentamicin, not knowing that his DNA had the variant which meant it would destroy his hearing.
“Gentamicin at the time was possibly the last resort,” he insists. “My parents did not have the time to contemplate the treatment’s outcomes. It kept me alive and that was their only aim and probably the only aim of all those people in ICU and Warrington Hospital who worked arduously and so daringly to keep me alive.”
After 10 months, several cardiac arrests and multiple operations, Mr Emson (a welder until his accident) left hospital in a wheelchair at half his normal weight and with a range of abdominal problems in addition to his deafness.
“Prognosis was not good for the amount of recovery I would make with walking and independence but I was determined not to let this beat me,” says Mr Emson. “The most heartbreaking thing for me when I became deaf was the loss of my music as I was a serious vinyl junkie. I also felt very isolated but I was alive.”
After a one-year studentship with The Deaf Trust to “learn to be deaf”, he adopted British Sign Language as a second language, which opened the door to a new deaf culture and eventually to his current job at Warrington and Vale Royal College providing classroom support for learners with additional needs. He was also supported by the trust to have a cochlear implant fitted in his left ear.
He is now happily married to Jane since 2018, walks well, has a full-time job and relishes the unexpected new life his traumas have offered him. But he welcomes a test for sensitivity to gentamicin-induced deafness: “It holds the possibility of reducing the trauma and pressure on the person and their family, should it be deemed necessary to introduce life-saving medicines to combat serious illness and could only advance research. It could also relieve pressure on the NHS in costs of extensive hospital stays and aftercare.”