Gene therapy restored hearing in deaf patients

Summary

Image: Caption: Maoli Duan. Photo: Ulf Sirborn“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 study comprised ten patients between the ages of 1 and 24 at five hospitals in China, all of whom had a genetic form of deafness or severe hearing impairment caused by mutations in a gene called OTOF. These mutations cause a deficiency of the protein otoferlin, which plays a critical part in transmitting auditory signals from the ear to the brain.Effect within a monthThe gene therapy involved using a synthetic adeno-associated virus (AAV) to deliver a functional version of the OTOF gene to the inner ear via a single injection through a membrane at the base of the cochlea called the round window.The effect of the gene therapy was rapid and the majority of the patients recovered some hearing after just one month. A six-month follow-up showed considerable hearing improvement in all participants, the average volume of perceptible sound improving from 106 decibels to 52.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.”No serious adverse reactionsThe results also show that the treat...