Pioneering gene therapy restores hearing for a young UK girl

In the United Kingdom, the first young patient with congenital deafness began to hear, thanks to gene therapy. What revolutionary gene therapy made this possible?

Opal Sandy was born with a mutation of the OTOF gene, which causes congenital deafness. Before she was one year old, she became the first patient to undergo a revolutionary gene therapy method. Now 18 months old, Opal can hear sounds as quiet as a whisper and starts speaking, uttering words like "mama" and "dada".

The girl is participating in a clinical trial, with participants being recruited in the United Kingdom, Spain, and the United States. Opal Sandy was cared for by a team of scientists at Addenbrooke's Hospital at the University of Cambridge in England.

The OTOF gene mutation in Opal prevents the production of functioning ciliated cells, which are responsible for receiving sound from the environment in a part of the inner ear called the cochlea. Gene therapy involves introducing a functioning copy of the OTOF gene into the damaged cells using a modified virus. This was administered to Opal through an infusion into her right ear under complete anaesthesia. Regeneron developed the drug.

Just a few weeks later, Opal could hear loud sounds in her right ear, such as clapping. After six months, doctors at Addenbrooke's Hospital confirmed that the ear had a nearly average level of hearing, even for quiet sounds like whispers.

The young patient received a cochlear implant in her left ear. This device "substitutes" for the non-functioning ciliated cells. The implant directly stimulates the hearing nerve by receiving wave vibrations, transmitting "sound" to the brain. Opal's five-year-old sister, Nora, who has the same type of deafness, is also doing well with a cochlear implant.

The girls' parents, Jo and James Sandy from Oxfordshire express their astonishment at the gene therapy results in Opal. However, they emphasized that the decision to allow their child to participate in testing this treatment method was not taken lightly. Opal's mother told bbc.com: "We were quite nervous to go down a different path to one that we knew had already worked so well for our eldest daughter. But it also sounded like a really unique opportunity"