In a landmark advancement for the treatment of hereditary hearing loss, researchers have successfully restored hearing in children and adults born with congenital deafness using a single injection of gene therapy. The therapy targets mutations in the OTOF gene, which encodes the otoferlin protein essential for transmitting sound signals from the inner ear to the brain.
The clinical trial, conducted by scientists from Sweden’s Karolinska Institutet in collaboration with hospitals and universities in China, involved ten participants aged between 1 and 24 years. All participants had profound hearing loss due to mutations in the OTOF gene. The therapy utilized a synthetic adeno-associated virus (AAV) to deliver a functional copy of the OTOF gene directly into the inner ear via the round window membrane at the base of the cochlea.
Results were promising: within one month of treatment, most participants experienced measurable improvements in hearing. By six months, all ten patients showed significant gains, with the average volume of perceptible sound improving from 106 decibels to 52 decibels. Younger patients, particularly those between five and eight years old, responded most robustly. One seven-year-old girl regained near-normal hearing and was able to engage in daily conversations with her mother four months post-treatment.
“This is a huge step forward in the genetic treatment of deafness, one that can be life-changing for children and adults,” said Dr. Maoli Duan, a consultant and docent at the Department of Clinical Science, Intervention and Technology at Karolinska Institutet and one of the study’s corresponding authors.
The therapy was well-tolerated, with no serious adverse reactions reported during the 6–12 month follow-up period. The most common side effect observed was a temporary reduction in neutrophil levels, a type of white blood cell.
This study marks the first time gene therapy has been tested in teenagers and adults with OTOF-related deafness, expanding upon previous research that primarily focused on younger children. The success of this trial opens the door for further exploration into gene therapies targeting other genetic causes of deafness, such as mutations in the GJB2 and TMC1 genes, which are more prevalent but present additional complexities in treatment.
The implications of this breakthrough are profound, offering hope to thousands affected by genetic forms of hearing loss. As research progresses, gene therapy may become a viable alternative to cochlear implants, providing more natural hearing restoration and improving the quality of life for individuals with hereditary deafness.
