A Shot of Sound: Gene Therapy Reverses Deafness in Just Weeks

Gene therapy has successfully reversed deafness in both children and adults by delivering a healthy gene directly to the ear. One injection led to rapid hearing recovery, especially in younger patients, with no serious side effects.

Breakthrough in Gene Therapy for Hearing Loss

A groundbreaking new study shows that gene therapy can restore hearing in children and adults born with severe hearing loss. All ten participants in the trial experienced noticeable improvement, and the treatment was safe and well-tolerated. The research was led by scientists at Sweden’s Karolinska Institutet in collaboration with several hospitals and universities in China. The findings were recently published in the journal Nature Medicine.

“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, consultant and docent at the Department of Clinical Science, Intervention and Technology, Karolinska Institutet, Sweden, and one of the study’s corresponding authors.

The participants, aged 1 to 24, had inherited a specific form of deafness caused by mutations in the OTOF gene. This gene is responsible for producing a protein called otoferlin, which is essential for transmitting sound signals from the ear to the brain.

Fixing a Critical Gene With a Single Injection

Researchers used a harmless virus, known as an adeno-associated virus (AAV), to carry a working copy of the OTOF gene into the inner ear. The gene was delivered through a single injection into a thin membrane at the base of the cochlea, called the round window.

The results were dramatic. Within just one month, most of the patients regained some level of hearing. After six months, every participant had improved significantly, with the average sound level they could detect improving from 106 decibels to 52—a major step toward functional hearing.

Best Outcomes in Children, But Adults Benefit Too

The younger patients, especially those between the ages of five and eight, responded best to the treatment. One of the participants, a seven-year-old girl, quickly recovered almost all her hearing and was able to hold daily conversations with her mother four months afterwards. However, the therapy also proved effective in adults.

“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 Dr Duan. “Hearing was greatly improved in many of the participants, which can have a profound effect on their life quality. We will now be following these patients to see how lasting the effect is.”

Safety Profile Shows Promise for Expansion

The results also show that the treatment was safe and well-tolerated. The most common adverse reaction was a reduction in the number of neutrophils, a type of white blood cell. No serious adverse reactions were reported in the follow-up period of 6 to 12 months.

“OTOF is just the beginning,” says Dr Duan. “We and other researchers are expanding our work to other, more common genes that cause deafness, such as GJB2 and TMC1. These are more complicated to treat, but animal studies have so far returned promising results. We are confident that patients with different kinds of genetic deafness will one day be able to receive treatment.”

Reference: “AAV gene therapy for autosomal recessive deafness 9: a single-arm trial” by Jieyu Qi, Liyan Zhang, Ling Lu, Fangzhi Tan, Cheng Cheng, Yicheng Lu, Wenxiu Dong, Yinyi Zhou, Xiaolong Fu, Lulu Jiang, Chang Tan, Shanzhong Zhang, Sijie Sun, Huaien Song, Maoli Duan, Dingjun Zha, Yu Sun, Xia Gao, Lei Xu, Fan-Gang Zeng and Renjie Chai, 2 July 2025, Nature Medicine.
DOI: 10.1038/s41591-025-03773-w

The study was conducted in collaboration with a number of institutions, including Zhongda Hospital, Southeast University, China, and was financed by several Chinese research programs and Otovia Therapeutics Inc., the company that has developed the gene therapy and that employs many of the researchers involved in the study. See the published paper for a full list of conflicts of interest.

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