Imagine if you had a genetic disorder that resulted in you being both Blind and Deaf, what would you do? This type of disorder is known as Usher Syndrome.
In Usher syndrome, the mutation occurs in at least ten genes, which can lead to the combination of deafness and blindness, and its occurrence depends upon the gene, which is mutated. Almost 125 million people around the world suffer from hearing loss due to genetic mutations.
Researchers are using gene therapy to see if they can cure Usher syndrome by editing its genetic basis for this disease. This was recently published in Nature titled “Gene therapy restores auditory and vestibular function in a mouse model of Usher syndrome type 1c.”
Usher syndrome is generally classified into three types: Usher type 1, type 2, and 3. Usher I and II are usually common forms, but only a small fraction of people from specific areas suffer from Usher III. In Type I Usher syndrome, people are born deaf, and they cannot hear or speak. Six genes are associated with this type of Usher syndrome, and the gene is involved in the formation of sensory hair bundles in the inner ear.
An adenoviral vector was utilized to re-introduce the expression of a non-mutated version of the gene USH1C in mice. Mutation of this gene causes Usher syndrome and leaves the mice deaf.
Gwenaëlle Géléoc and her colleagues from Boston Children’s Hospital in Massachusetts studied newborn mice with a form of Usher syndrome type I. The mice were injected with a synthetic virus that carried a healthy version of the gene for a protein known as harmonin. This protein is usually present in the hair cells of the inner ear and helps in transmitting auditory signals to the brain. The researchers found out that the mice had given the response to the gene very well and could listen to the sounds properly, even as quiet as whisper like a normal mouse. These mice also performed well in balance tests as normal mice.
Another study which was conducted by Luk Vandenberghe at the Schepens Eye Research Institute of Massachusetts Eye and Ear in Boston and his colleagues found that the same virus delivered genes to a large number of the target hair cells in the mouse ear.
Treatment with the adenovirus during the early stages of development resulted in restoration in the mouse’s ability to hear.