Gene therapy restores hearing in 10 deaf patients

Ten patients with congenital deafness or severe hearing impairment have recovered their hearing thanks to a new gene therapy. The study, conducted by the Karolinska Institute (Denmark) in collaboration with hospitals and universities in China, published in the journal Nature Medicine , represents a major step forward in the genetic treatment of deafness, "as it can change the lives of children and adults," says Maoli Duan, one of the study's authors.

The ten patients, aged between 1 and 24, were from five hospitals in China and all had a genetic form of deafness or severe hearing loss caused by mutations in the OTOF gene. These mutations cause a deficiency in the protein otoferlin , which plays a key role in transmitting auditory signals from the ear to the brain.

The gene therapy used a synthetic adeno-associated virus (AAV) to deliver a functional version of the OTOF gene to the inner ear via a single injection through a membrane at the base of the cochlea called the round window.

The effect of gene therapy was rapid, and most patients partially recovered their hearing within one month.

At six months, all participants showed significant hearing improvement, with the average perceptible sound volume improving from 106 decibels to 52.

Younger patients, especially those between five and eight years old, responded best to treatment.

One of the participants, a seven-year-old girl, quickly recovered almost all of her hearing and was able to hold daily conversations with her mother four months later.

" This is the first time the method has been tested on adolescents and adults ," Duan said.

“OTOF is just the beginning,” Duan says. “We are expanding our work to other, more common genes that cause deafness, such as GJB2 and TMC1. These are more complex to treat, but animal studies so far have yielded promising results. We are confident that patients with different types of genetic deafness will one day be able to receive treatment.”