Opal Sandy
Opal Sandy, who was born completely deaf because of a rare genetic condition, and can now hear unaided for the first time after receiving ground-breaking gene therapy at 11-months-old, reads with her mother Jo at their home in Eynsham, Oxfordshire. Image Credit: PA via Reuters

LONDON: An 18-month old British girl who was born completely deaf is believed to be the youngest person to have their hearing restored after undergoing groundbreaking new gene therapy.

Several medical teams around the world including in China and the United States have been trialling similar treatments with good results for hereditary deafness that focuses on a rare genetic mutation.

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But UK ear surgeon Manohar Bance said the toddler, Opal, was the first person in the world to receive therapy developed by US biotech firm Regeneron and “the youngest globally that’s been done to date as far as we know”.

Opal was treated at Addenbrooke’s Hospital in Cambridge, part of Cambridge University Hospitals NHS Foundation Trust, in eastern England.

Bance called the results of Opal’s surgery “spectacular - so close to normal hearing restoration. So we do hope it could be a potential cure”.

He said it came on the back of decades of work and marked “a new era in the treatment of deafness”.

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What genetic defect caused hearing loss?

The little girl, from Oxfordshire in south central England, has a genetic form of auditory neuropathy, which is caused by the disruption of nerve impulses travelling from the inner ear to the brain.

Auditory neuropathy can be caused by a fault in the OTOF gene, which is responsible for making a protein called otoferlin. This enables cells in the ear to communicate with the hearing nerve.

How British toddler’s hearing has been restored after groundbreaking gene therapy
Image Credit: Gulf News

How was it rectified?

The therapy uses a modified, harmless virus to deliver a working copy of the Otof gene into these cells. Given as an infusion into the ear, the therapy replaces faulty DNA causing her type of inherited deafness.

Opal had the therapy in her right ear, under general anaesthetic, and a cochlear implant put into her left.

How gene therapy works?
First, DNA is added to a harmless virus to create the gene therapy. Then, the gene therapy is introduced into the inner ear to repair the damaged hair cells, enabling the child to hear.

Just a few weeks later, she could hear loud sounds, such as clapping, in her right ear. And after six months, her doctors, at Addenbrooke’s Hospital, in Cambridge, confirmed that ear had almost normal hearing for soft sounds - even very quiet whispers.

WLD OPAL-1715257655177
Opal Sandy (second left), who was born completely deaf because of a rare genetic condition, and can now hear unaided for the first time after receiving ground-breaking gene therapy at 11-months-old, pictured with her mother Jo, father James and sister Nora, at their home in Eynsham, Oxfordshire.

Bance said that following surgery last September, Opal’s hearing was now “close to normal” with further improvement expected.

A second child received the gene therapy in Cambridge with positive results seen six weeks after the surgery.

What percentage of hearing loss in babies is due to genetic cause?

Experts hope the therapy could also work for other types of profound hearing loss. Up to 60% of hearing-loss cases in children have a genetic cause.

3-stage trial
The trial consists of three parts, with three deaf children, including Opal, receiving a low dose of gene therapy in one ear only.
A different set of three children will get a high dose on one side. Then, if that is shown to be safe, more children will receive a dose in both ears at the same time.
Up to 18 youngsters from the UK, Spain and the United States are being recruited to the trial and will be followed up for five years.

And Prof Bance hopes the trial can lead to gene therapy being used for more common types of hearing loss.

“What I am hoping is that we can start to use gene therapy in young children... where we actually restore the hearing and they don’t have to have cochlear implants and other technologies that have to be replaced,” he told BBC.

Does the treatment work for adults?
The treatment was developed especially for children with OTOF mutations, and a second child who has had the same surgery is also seeing positive results.
Prof Bance said: “The younger we can restore hearing, the better for all children because the brain starts to shut down its plasticity [adaptability] after the age of about three or so.”
Opal’s experience, alongside other scientific data from the trial, is being presented at the American Society of Gene and Cell Therapy in Baltimore, in the US.

What's the current treatment for auditory neuropathy?

China has been working on targeting the same gene though Bance said theirs used a different technology and slightly different mode of delivery.

Medics in Philadelphia have also reported a good outcome with a type of gene therapy on an 11-year-old boy.

Opal was the first person to take part in a gene therapy trial being carried out in Cambridge by Bance. “My entire life, gene therapy has been ‘five years away’... to finally see something that actually worked in humans... It was quite spectacular and a bit awe-inspiring really,” he said.

Bance said the current treatment for auditory neuropathy was implants.