A groundbreaking gene therapy has shown promising results in restoring hearing in people with genetic deafness, with a single injection leading to significant improvements in just weeks.
In a world-first clinical trial conducted by researchers at Sweden’s Karolinska Institutet, scientists successfully used gene therapy to treat children and adults with a rare form of inherited hearing loss. The therapy targeted a mutation in the OTOF gene, responsible for producing otoferlin — a protein essential for transmitting sound from the inner ear to the brain.
Ten participants with congenital or severe hearing impairment caused by OTOF mutations received a one-off injection of the healthy gene directly into the inner ear. The treatment used a harmless, synthetic version of an adeno-associated virus to deliver the corrected gene.
The results, published in Nature Medicine, were remarkable. After just one month, most participants showed rapid improvements in hearing. Six months after treatment, all participants demonstrated a significant reduction in the volume of sound required for them to hear — from an average of 106 decibels down to 52.
The youngest participants responded best. A seven-year-old girl in the trial regained almost full hearing and was holding conversations with her mother just four months after receiving the injection.
“This is the first time the method has been tested in teenagers and adults,” said Dr Maoli Duan, a researcher involved in the study. “Hearing was greatly improved in many of the participants, which can have a profound effect on their life quality.”
The therapy also appeared safe and well-tolerated. No serious side effects were reported during the six to twelve-month follow-up period. The most common reaction was a mild drop in neutrophil levels, a type of white blood cell, but this resolved without complication.
While the results are early and limited to a small group, experts are hopeful. The therapy’s success in children and adults opens new doors for future treatment of genetic hearing conditions. Dr Duan said the team is now exploring therapies for other more common genes linked to deafness, such as GJB2 and TMC1. Although these genes are more complex to treat, early trials in animals have shown encouraging results.
“Hearing loss can have a deep impact on quality of life, especially when it occurs from birth,” said Dr Duan. “This is a major step forward in showing that gene therapy can make a real difference. OTOF is just the beginning.”
Globally, an estimated 430 million people experience disabling hearing loss, according to the World Health Organization. For those with genetic forms of deafness, treatments have typically been limited to hearing aids or cochlear implants. Gene therapy could eventually offer a more permanent solution, especially when administered early in life.
Further research will determine how long the benefits last and whether the therapy can be scaled for wider use. But for families affected by genetic hearing loss, the early signs are cause for cautious optimism.
