Six children born deaf can now hear following an experimental treatment involving an injection into the ear. Researchers, jointly led by Harvard Medical School and Fudan University in China, administered the treatment to children aged one to seven who had inherited deafness due to a mutation in the OTOF gene. This gene mutation affects the production of a crucial protein responsible for transmitting signals from the ear to the brain.
During the 26-week trial, five of the six children showed significant improvements in their hearing, with four of them experiencing substantial outcomes, as reported by Harvard Medical School. The findings of this study were published in Lancet. Improved hearing is vital for language development, and the researchers also observed enhancements in speech perception among the responding children.
Co-senior author Zheng-Yi Chen, an associate professor at Harvard Medical School and a researcher at Mass Eye and Ear’s Eaton-Peabody Laboratories, expressed optimism about the potential of this gene therapy approach for various genetic forms of deafness.
The OTOF gene produces the otoferlin protein, crucial for transmitting sound signals from the cochlea to the brain. The mutation in this gene poses an ideal target for gene therapy due to its simplicity and lack of physical damage to cochlear cells.
The study received a considerable response from potential participants, reflecting the urgent need for effective treatments for congenital deafness. However, only six children were ultimately enrolled in the trial. Among them, four had cochlear implants, which, coupled with training, allowed for speech and sound interpretation.
The gene therapy procedure involved inserting the gene into the cochlea using a modified virus. To overcome the gene’s size limitation, researchers divided it into two parts and delivered each part using a separate virus. Despite insertion into different spots in the cells’ DNA, the cellular machinery assembled the complete protein.
Signs of hearing improvement were observed in five of the six participants, with three older children able to comprehend speech without their cochlear implants after 26 weeks. However, one participant did not show any improvement, possibly due to an immune reaction to the viral vector used in the treatment.
