Treating Deaf Mice with Gene Therapy

In the laboratory of Boston Children's Hospital, a method for treating genetic deafness is taking shape. Jeff Holt, the lead researcher of this project, states that if all stages proceed well, children whose deafness is caused by genetic mutations will never remain deaf in the future. Reuters reported on Wednesday, September 2, that this medical team aims to solve the problem of childhood deafness at its source; they want to correct defective genes that make up part of the inner ear using engineered viruses. In other words, the core of the work is based on viral gene therapy. Mr. Holt says, "Our strategy is to take a viral vector and remove the viral genes so that these viruses do not cause disease, and they replace the 'TMC1' gene with the correct DNA sequence, which is one of the essential factors for having hearing ability." The 'TMC1' gene is responsible for forming proteins that convert sound waves into electrical signals. These signals are then transmitted to the brain and processed. According to this report, Mr. Holt's team has restored the hearing ability of two types of deaf mice whose 'TMC1' genes are similar to humans by testing their idea. They had introduced an engineered virus named 'AAV1' that functions similarly to the 'TMC1' gene into the inner ear of the mice. The hearing recovery test for these two types of deaf mice involved placing them in a closed area and suddenly sending a loud sound into the area. The deaf mice showed no reaction to the sound, but after treatment, the two mice reacted to the sound and jumped. Mr. Holt states that there are at least seventy different genetic mutations that cause deafness in adulthood, but gene therapy has the potential to cure all these disorders in the future, so that no child will have hearing problems in the future.