A new study led by researchers at Karolinska Institutet shows that gene therapy can significantly improve hearing in children and adults with congenital deafness or severe hearing impairment. The treatment improved hearing in all 10 patients involved and was well-tolerated throughout the trial.
Collaborative Study Targets Genetic Deafness
Researchers conducted the study, titled “AAV gene therapy for autosomal recessive deafness 9: A single-arm trial,” in collaboration with hospitals and universities in China and published it in Nature Medicine. The patients, aged 1 to 24, all had mutations in the OTOF gene, which causes a deficiency in otoferlin—a protein essential for transmitting sound signals from the ear to the brain. As per Medical Xpress, this study marks a significant breakthrough in treating genetic deafness.
How the Gene Therapy Works
Scientists delivered a functional copy of the OTOF gene to the inner ear using a synthetic adeno-associated virus (AAV). They injected this gene therapy through the round window membrane, located at the base of the cochlea. The effect was rapid, with most patients recovering some hearing within one month. At six months, all participants showed substantial hearing improvement, with average hearing levels improving from 106 decibels (profound hearing loss) to 52 decibels (moderate hearing loss).
Best Results Observed in Children, But Adults Benefit Too
Younger patients, especially those between five and eight years old, responded most positively. For instance, a seven-year-old girl regained nearly full hearing and could hold daily conversations with her mother within four months of treatment. However, the therapy also improved hearing in adult patients. Dr. Maoli Duan, a lead author from Karolinska Institutet, noted that this is the first time researchers have successfully tested this therapy across a broader age range, including teenagers and adults.
Safety and Future Prospects
The gene therapy was safe and well-tolerated, with no serious adverse reactions reported over a follow-up period of six to twelve months. The most common side effect was a temporary reduction in neutrophils, a type of white blood cell. Dr. Duan emphasized that OTOF is only the beginning. The team and other researchers are now working on gene therapies targeting more common deafness-causing genes such as GJB2 and TMC1, which are more complex but show promise in animal studies. The research was supported by Zhongda Hospital, Southeast University, Chinese research programs, and Otovia Therapeutics Inc.