For an incurable disorder that causes both blindness and deafness, Harvard researchers have created a “mini gene” therapy. A uncommon, disabling genetic illness called Usher Syndrome type 1F is characterised by deafness, decreased balance, and progressive visual loss.
Now, a group of scientists from The Ohio State University, Massachusetts Eye & Ear, and Harvard Medical School have made an essential first move towards developing a gene treatment for Usher Syndrome type 1F.
They just had their research on mice published in the magazine Nature Communications. In order to replace the gene that is mutated in Usher 1F, scientists created a “mini gene”—a condensed version of a gene. The mutation prevents the inner ear’s hair cells from manufacturing a crucial protein necessary for sound transmission. The small gene in mice enhanced the production of the deficient protein. Allowing the hair cells in the ears to once again detect sound.
Applying knowledge to a fresh issue
Usher Syndrome is characterised by severe hearing loss or total deafness at birth, poor balance. And progressive visual loss due to retinal degeneration. Most people become blind by maturity. These issues are brought on by a mutation that prevents the synthesis of a protein called protocadherin-15, which is required for the proper operation of cells in the auditory and visual systems and exists in slightly different forms in the ear and eye.
The function of protocadherin-15 in the inner ear has long piqued the interest of scientists in the Corey lab. They were specifically interested in how the protein aids in the conversion of vibrations from the environment into electrical impulses that the brain perceives as sound by sensory receptors known as hair cells in the ear.
Smaller genes form when genes break
All 25,000 atoms in the external structure of inner-ear protocadherin-15 were meticulously mapped in the first stage. This was done by co-senior author Marcos Sotomayor, a former research fellow at HMS and current assistant professor of chemistry and biochemistry at Ohio State.
Sotomayor used a combination of cryo-electron microscopy and X-ray crystallography to determine that the protein is composed of atoms arranged into what appears to be 11 links in a chain.
Zebrafish are a better model since they lose their vision more quickly. And severely than mice do when protocadherin-15 isn’t formed in the retina. Thus the Corey team is currently evaluating the small gene in zebrafish eyes. If the tiny gene works in the retina of the zebrafish. Scientists will test the method in mammals and finally in humans.
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