A recent study conducted by researchers at Karolinska Institutet, in collaboration with various hospitals and universities in China, has demonstrated that gene therapy can significantly enhance hearing in individuals with congenital deafness or severe hearing loss. The findings, published in the journal Nature Medicine, report that all ten patients treated in the study experienced measurable improvements in their hearing abilities.
The trial focused on patients aged 1 to 24 who had a genetic form of deafness associated with mutations in the OTOF gene. These mutations hinder the production of otoferlin, a protein critical for transmitting sound signals from the inner ear to the brain. To address this, researchers employed a synthetic adeno-associated virus (AAV) to deliver a functional version of the OTOF gene directly into the inner ear through a single injection.
Results were observed rapidly, with most participants regaining some hearing within a month and all showing improvement by the six-month mark. On average, the sound detection threshold improved significantly from 106 decibels to 52 decibels. Notably, younger patients, particularly those aged five to eight, exhibited the most pronounced enhancements, with one seven-year-old girl nearly regaining full hearing shortly after treatment.
The therapy was found to be safe and well-tolerated, with the most common side effect being a temporary decrease in neutrophils, a type of white blood cell. Importantly, no serious adverse reactions were reported during the follow-up period of six to twelve months.
Researchers, including Dr. Maoli Duan, expressed optimism about the potential for expanding gene therapy to address other genetic causes of hearing loss, such as mutations in the GJB2 and TMC1 genes. Further studies are planned to assess the long-term effectiveness of the therapy and explore additional treatment avenues.