Unlocking the World of Sound: A Breakthrough Gene Therapy Brings Hope to the Deaf Community

Saturday - February 3 2024, 14:11 UTC - 1 year ago

A groundbreaking gene therapy has successfully restored the hearing of an 11-year-old deaf boy, changing his world and offering hope to the deaf community. This therapy involves delivering a healthy copy of a mutated gene back into the body, and has shown promising results in its first clinical trial. With an estimated 466 million people worldwide suffering from disabling hearing loss, this breakthrough offers new possibilities for gene therapy and research.

When Aissam Dam had the strange device connected to his ear, he had no idea it was going to change his life.

An 11-year-old boy, Aissam was born deaf due to a single gene mutation. In October 2023, he became the first person in the US to receive a gene therapy that added a healthy version of the mutated gene into his inner ear. Within four weeks, he began to hear sounds.

Four months later, his perception of the world had broadened beyond imagination. For the first time, he heard the buzzing of traffic, learned the timbre of his father’s voice, and wondered at the snipping sound scissors made during a haircut.

Aissam is participating in an ongoing clinical trial testing a one-time gene therapy to restore hearing in kids like him. Due to a mutation in a gene called otoferlin, the children are born deaf and often require hearing aids from birth. The trial is a collaboration between the Children's Hospital of Philadelphia and Akouos, a subsidiary of the pharmaceutical giant Eli Lilly.

"Gene therapy for hearing loss is something physicians and scientists around the world have been working toward for over 20 years," said Dr. John Germiller at the Children's Hospital of Philadelphia, who administered the drug to Aissam, in a press release. "These initial results show that it may restore hearing better than many thought possible." .

While previously tested in mice and non-human primates, the team didn't know if the therapy would work for Aissam. Even if it did work, they were unsure how it would affect the life of a deaf young adult- essentially introducing him to an entirely new sensory world.

They didn't have to worry. "There's no sound I don't like...they're all good," Aissam said to the New York Times.

A Broken Bridge .

Hearing isn't just about picking up sounds, it's also about translating sound waves into electrical signals our brains can perceive and understand.

At the core of this process is the cochlea, a snail-like structure buried deep inside the inner ear that translates sound waves into electrical signals that are then sent to the brain.

The cochlea is a bit like a roll-up piano keyboard. The structure is lined with over 3,500 wiggly, finger-shaped hairs. Like individual piano keys, each hair cell is tuned to a note. The cells respond when they detect their preferred sound frequency, sending electrical pulses to the auditory parts of the brain. This allows us to perceive sounds, conversations, and music.

For Aissam and over 200,000 people worldwide, these hair cells are unable to communicate with the brain from birth due a mutation in a gene called otoferlin. Otoferlin is a bridge. It enables the hair cells lining the cochlea to send chemical messages to nearby nerve fibers, activating signals to the brain. The mutated gene cuts the phone line, leading to deafness.

Hearing Helper .

In the clinical trial, scientists hoped to restore the connection between inner-ear cells and the brain using a gene therapy to add a dose of otoferlin directly into the inner ear.

This was not straightforward. Otoferlin is a very large gene, making it difficult to directly inject into the body. In the short gene fragments which are typically injected, restoring a full-length otoferlin is unlikely.