Single Gene Therapy Injection Restores Hearing in Deaf Patients Within Weeks

A revolutionary gene therapy has successfully restored hearing in people born with congenital deafness, with all ten patients in a groundbreaking clinical trial experiencing significant improvements within weeks of treatment. The therapy, which involves a single injection of a functional gene directly into the inner ear, represents a major breakthrough in treating genetic hearing loss and could transform the lives of millions worldwide who suffer from similar conditions.

The international study, published in Nature Medicine and led by researchers at Karolinska Institutet in collaboration with Chinese hospitals and universities, focused on patients with mutations in the OTOF gene. These genetic defects prevent the body from producing sufficient amounts of otoferlin, a protein essential for transmitting sound signals from the inner ear to the brain. The ten participants, ranging in age from 1 to 24 years, all suffered from this specific form of inherited deafness.

The treatment delivered remarkable results with unprecedented speed. Most patients began to regain hearing within just one month of receiving the therapy, which uses a synthetic adeno-associated virus (AAV) to carry a working copy of the OTOF gene directly into the cochlea through the round window membrane. After six months, all participants showed clear improvement, with the average sound detection threshold improving dramatically from 106 decibels to 52 decibels.

"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, consultant and docent at Karolinska Institutet's Department of Clinical Science, Intervention and Technology. The most striking improvements were observed in younger patients, particularly children between ages five and eight. One seven-year-old girl regained nearly complete hearing and was able to engage in normal conversations with her mother just four months after treatment.

The therapy demonstrated excellent safety profiles, with the most common side effect being a temporary decrease in neutrophils, a type of white blood cell. No serious adverse reactions were reported during the 6 to 12-month follow-up period. Dr. Duan emphasized that this represents just the beginning of gene therapy applications for hearing loss, with research teams already expanding their work to target other common genetic causes of deafness, including GJB2 and TMC1 mutations, which affect even larger populations of hearing-impaired individuals.