One Injection Restores Hearing in Deaf Children

A 2025 gene-therapy study by Karolinska Institutet restored hearing in all 10 participants—children and adults with congenital OTOF-related deafness—within just one month of a single inner-ear injection  . Average hearing thresholds dramatically dropped from 106 dB (near deafness) to 52 dB (moderate hearing), with some kids—including a 7-year-old—hearing nearly normally within four months.

The therapy uses an adeno-associated virus (AAV) to deliver a healthy copy of the OTOF gene directly to the cochlea via a one-time injection. The treatment was well-tolerated across ages 1–24, with no serious side effects reported during 6–12 months of follow-up—all received a functioning otoferlin protein that reactivated the ear’s sound-transmitting machinery  .

This was a phase I/II single-arm clinical trial, giving powerful early proof-of-concept in humans. While the sample size was small and there was no control group, the consistency of hearing restoration and safety across all participants is groundbreaking.

Hearing loss due to certain genetic mutations may soon have a real cure—one shot, one lifetime fix is no longer a dream.