A new kind of hearing treatment is changing the picture for some families living with genetic deafness. It uses a single inner ear injection to supply a missing gene and restart the hearing pathway.

In a new clinical trial, children began to detect sounds within weeks and the group’s average hearing threshold improved from 106 dB to 52 dB. Adults improved too, though not as strongly.

How the hearing treatment works

Maoli Duan, consultant and docent at the Department of Clinical Science, Intervention and Technology (CLINTEC) at Karolinska Institutet, is a corresponding author on the study. He and a large team worked with hospitals in China to test the approach in people aged 1 to 24.

The otoferlin protein, which is needed for sending sound signals from the ear to the hearing nerve, helps inner ear cells pass those signals along.

When the OTOF gene is mutated, the process is blocked, so the nerve never receives the signals even though the ear cells still look normal.

People with OTOF related deafness often do not benefit from hearing aids. Cochlear implants can help, but a genetic fix could restore the missing step in the ear’s own circuit.

This type of hearing loss is sometimes called auditory synaptopathy. The ear senses vibration, yet the message cannot move along the nerve with the timing that speech requires.

Language learning depends on early and consistent access to sound. Better hearing in the early school years can support speech clarity, literacy, and social connection.

Using a virus to restore hearing

Doctors placed a specially designed virus into the ear through the round window, a thin layer at the base of the cochlea.

The virus carried a healthy copy of the OTOF gene into the cells, allowing them to make the missing protein again.

The virus used in this treatment was specially designed so it could enter the delicate cells of the inner ear that handle sound.

Once inside, it delivered the healthy gene where it was needed. Doctors found that giving just a single injection in each ear was enough for the patients who took part in the trial.

Surgeons aim the dose to a tiny space just beyond the round window membrane. The volume is small and the goal is a quiet delivery that protects delicate structures while letting the vector spread along the spiral.

Most trials start with one ear so doctors can compare progress and manage risk. If hearing grows steadily and safety holds, a second ear may be considered in future protocols.

Hearing treatment audible range

Researchers tracked hearing with behavioral tests and with objective signals such as the Auditory Brainstem Response (ABR). They looked at how soft a tone needed to be before a response showed up in the brain pathway.

The youngest children tended to do best, with the strongest gains in the 5 to 8 age range. Speech understanding followed as thresholds dropped, and several families reported everyday conversations that had never been possible before.

“Smaller studies in China have previously shown positive results in children, but this is the first time that the method has been tested in teenagers and adults, too,” says Duan. 

The testing included how well the ear detects clicks and tone bursts. They also checked steady state responses that reflect how the brainstem locks to rapid sound patterns.

Objective and behavioral measures answer different questions about hearing. As neural responses gain strength and reliability, pure tone thresholds often improve, which helps in quiet and in noise.

Safety signals and limits

No serious adverse events were reported in early follow up. The most frequent lab change was a lower percentage of neutrophils, a type of white blood cell, and this was mild.

The trial was small and single arm, so there was no placebo comparison group. Durability of the benefit will take years to confirm, and the team plans long term monitoring.

As with any procedure in the inner ear, infection and pressure related injury are possible, though rare in expert hands. Vector spread beyond the treated ear is monitored, and patients are followed with routine exams and labs.

Future of hearing treatments

There are still no approved gene therapies for genetic hearing loss in the United States. Families considering research participation need careful counseling about risks, alternatives, and realistic expectations.

Access will hinge on trained surgical teams and centers that can support careful testing before and after treatment. Insurance coverage, travel, and support services will shape who can benefit and how fast programs roll out.

“This is a huge step forward in the genetic treatment of deafness, one that can be life-changing for children and adults,” says Maoli Duan.

The statement reflects both the speed of early benefit and the possibility of broader access if future trials confirm safety and efficacy.

Researchers emphasized that OTOF is only the first step, and they are already turning their attention to other genes, including GJB2 and TMC1, which are among the most common causes of inherited hearing loss.

The study is published in Nature Medicine.

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