After focusing on the transmembrane channel-like protein 1 (TMC1) gene, researchers at Boston Children's Hospital and Harvard Medical School were able to restore hearing in mice with deafness caused through genetic disorders using gene therapy.
According to GEN News, "TMC1 forms a channel that allows calcium to enter the cell when moved by sound waves, including an electrical signal that is sent to the brain and interpreted as an auditory signal." Close to 8% of genetic deafness cases are the result of TMC1 issues.
While not yet ready for clinical trials, senior author Jeffrey Holt, Ph.D., associate professor of otolaryngology explains that this type of gene therapy could be developed for use in humans.
Along with his colleagues, Dr. Holt designed a virus to contain a working copy of TMC1 and a promoter sequence, to make sure that the gene was turned on correctly. This was injected into the inner ear of two different mouse strains. In the first, TMC1 was completely deleted and in the second, the Beethoven mice, a mutation was present where TMC1 was rendered ineffective.
In order to test the hearing of mice that received the virus, scientists placed them in a "startle box," where loud tones were sounded and the reaction of the mice were measured and observed through a force plate on the floor below them. Surprisingly, both strains of mice were able to detect the auditory signals.
Researchers also observed that the mice who had received gene therapy were able to hear addition sounds in the 80-decibel range.
Dr. Holt's hope is to start clinical trials of TMC1 gene therapy within 5 to 10 years through a partnership with Boston Children's department of otolaryngology.
