Gene Therapy Restores Hearing in All Ten Patients Born With Congenital Deafness

A groundbreaking gene therapy study has demonstrated that hearing can be significantly restored in people born with congenital deafness. Researchers at Karolinska Institutet, working with hospitals and universities in China, treated ten patients using a single injection that delivered a working copy of the OTOF gene directly into the inner ear.

The results were remarkable: all ten patients showed clear improvement after six months. On average, the sound level patients could detect improved from 106 decibels to 52 decibels — a dramatic change that opens the door to everyday conversation. Most patients began to regain some hearing within just one month of treatment.

“Researchers at Karolinska Institutet, working with hospitals and universities in China, treated ten patients using a single injection that delivered a working copy of the OTOF gene directly into the inner ear.”

Children showed the most dramatic responses, especially those between ages five and eight. One seven-year-old girl regained nearly full hearing and was able to have everyday conversations with her mother just four months after receiving the treatment. The emotional impact on families has been profound.

The therapy uses a synthetic adeno-associated virus (AAV) to deliver the working gene through a single injection at the round window membrane of the inner ear. The treatment was shown to be safe and well-tolerated, with the most common side effect being a temporary decrease in neutrophils. No serious adverse reactions were observed during the six-to-twelve-month follow-up period.

The OTOF gene provides instructions for making otoferlin, a protein essential for transmitting sound signals from the inner ear's hair cells to the brain. Mutations in this gene account for a significant proportion of hereditary deafness cases worldwide.

Researchers are now expanding their work to target other common deafness-causing genes, including GJB2 and TMC1, which together account for a much larger share of genetic hearing loss. The success of this approach could eventually offer treatment to millions of people born with hereditary deafness.