Baby born deaf can hear after breakthrough gene therapy

A baby girl who was born deaf can hear unaided for the first time, thanks to ground-breaking gene therapy at Addenbrooke's Hospital.

Opal Sandy from Oxfordshire is the first patient treated in a global gene therapy trial, which shows “mind-blowing” results. She is the first British patient in the world and the youngest child to receive this type of treatment.

Opal was born completely deaf because of a rare genetic condition, auditory neuropathy, caused by the disruption of nerve impulses travelling from the inner ear to the brain.

Within four weeks of having the gene therapy infusion to her right ear, Opal responded to sound, even with the cochlear implant in her left ear switched off. By 24 weeks, clinicians confirmed she had close to normal hearing levels for soft sounds, such as whispering, in her treated ear.

Now 18 months old, Opal can respond to her parents’ voices and can communicate words such as “Dada” and “bye-bye.”

The CHORD trial, which started in May 2023, aims to show whether gene therapy can provide hearing for children born with auditory neuropathy.

Dr Richard Brown, Consultant Paediatrician at CUH, who is an Investigator on the CHORD trial, said: “The development of genomic medicine and alternative treatments is vital for patients worldwide, and increasingly offers hope to children with previously incurable disorders. It is likely that in the long run such treatments require less follow up so may prove to be an attractive option, including within the developing world. Follow up appointments have shown effective results so far with no adverse reactions and it is exciting to see the results to date."

The new Children’s hospital will house the state-of-the-art Cambridge Children's Research Institute, solely dedicated to improving the health of children and young people. The Research Institute will house six collaborative research centres, including the Genomic Medicine Centre, which will develop advanced diagnostic testing and gene therapies.

Auditory neuropathy can be due to a variation in a single gene, known as the OTOF gene. Approximately 20,000 people across the UK, Germany, France, Spain, Italy and UK are deaf due to the mutation. This hearing loss is not commonly detected until children are 2 or 3 years of age – when a delay in speech is likely to be noticed.

Professor Manohar Bance, an ear surgeon at Cambridge University Hospitals NHS Foundation Trust and chief investigator of the trial described the results as "spectacular".

“Gene therapy has been the future of otology and audiology for many years and I’m so excited that it is now finally here. This is hopefully the start of a new era for gene therapies for the inner ear and many types of hearing loss.”

Professor Bance added: “We have a short time frame to intervene because of the rapid pace of brain development at this age. Delays in the diagnosis can also cause confusion for families as the many reasons for delayed speech and late intervention can impact a children’s development.”

“More than sixty years after the cochlear implant was first invented – the standard of care treatment for patients with OTOF related hearing loss – this trial shows gene therapy could provide a future alternative. It marks a new era in the treatment for deafness. It also supports the development of other gene therapies that may prove to make a difference in other genetic related hearing conditions, many of which are more common than auditory neuropathy.”

Mutations in the OTOF gene can be identified by standard NHS genetic testing. Opal was identified as being at risk as her older sister has the condition; this was confirmed by a genetic test result when she was 3 weeks old.

Opal was given an infusion containing a harmless virus (AAV1). It delivers a working copy of the OTOF gene and is delivered via an injection in the cochlea during surgery under general anaesthesia. During surgery, while Opal was given the gene therapy in right ear, a cochlear implant was fitted in her left ear.