Scientists have reported impressive results from the largest and longest clinical trial to date of gene therapy for congenital deafness. Over several years of observation, about 90% of participants—children and adults with complete hearing loss—experienced significant improvements in hearing.
The study, published in the journal Nature, involved 42 participants from China, mostly children as well as several adults. All had total hearing loss prior to treatment. After therapy, most patients began to experience improvements within the first few weeks, with hearing continuing to recover gradually over about a year before stabilizing.
The most pronounced effects were observed in children: some were able to hear normal speech and even whispers. Improvements in adults were less dramatic but still noticeable. Overall, after two years of follow-up, all patients who responded to the therapy could distinguish spoken language, and some could even hear whispers.
The therapy targets one of the genetic causes of congenital deafness—mutations in the OTOF gene, which is responsible for producing a protein essential for transmitting sound signals to the brain. When this gene is defective, the inner ear cannot properly convert vibrations into nerve impulses.
The treatment uses a harmless virus to deliver a corrected copy of the gene into cells. Unlike hearing aids or cochlear implants, this approach is not an external device but an attempt to restore the hearing mechanism itself from within.
No serious side effects were reported. Some patients experienced mild, temporary reactions, such as dizziness or changes in immune cell activity.
Interestingly, the degree of hearing recovery depended not only on age but also on the condition of the inner ear structures: those with less damage experienced greater improvements.
Some participants not only began to hear better but also developed speech—including a child who had never used a cochlear implant and began to say their first words after treatment.
Scientists describe the results as a “turning point” in the treatment of genetic deafness. However, they emphasize that cochlear implants will likely remain the primary treatment method for a long time, while gene therapy may become an alternative for certain patients.
The technology is currently undergoing further trials and moving toward possible approval in different countries. If successfully implemented, it could become one of the first gene therapies capable not just of compensating for hearing loss but of partially restoring it naturally.
