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Major breakthrough in addressing rare genetic disorder leading to deafness and blindness


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Usher syndrome type 1F is a rare but very severe genetic disorder that causes deafness, imbalance, and progressive blindness.

A team of researchers from Harvard Medical School, the Massachusetts Eye and Ear Institute and Ohio State University have taken an important first step towards developing a gene therapy for this disease.

The study, which was conducted in mice, is described April 26 in Nature Communications.

Scientists have developed a “mini-gene” (a shortened version of the gene) to replace the gene mutated in Usher syndrome type 1F.

The mutation renders inner ear hair cells unable to produce a key protein involved in sound transmission.

In mice, the mini-gene increased the production of the missing protein, which allowed hair cells to perceive sound and restore hearing.

Because vision loss in Usher syndrome type 1F is associated with a slightly different form of the same protein, the researchers say the same approach could be helpful in preventing blindness.

“Patients with Usher syndrome type 1F are born with severe hearing loss and progressive vision loss, and so far we have been able to offer very few solutions for this condition,” explained co-author Arthur Injikulian, assistant professor of otolaryngology at Harvard Medical School. .”.

I am very glad that this work is finally published! This is the first of several articles summarizing our collaborative work on the development of a mini-gene therapy for Usher syndrome type 1F, joining forces with Corey and Sotomayor Laboratories!

– Artur Indjikulyan (@IndArtur) April 26, 2023

The researchers plan to continue testing the mini-gene in other animal models and eventually hope to test it in humans.

“It is absolutely devastating to be born deaf and then lose your sight, so we hope this gene microcosm eventually proves to be a cure for this disease,” said co-author David Corai, a professor of translational medicine at the Blavatnik Institute at Harvard. Medical school.

Children with Usher syndrome are usually born completely deaf or have severe hearing loss, balance problems, and eventually lose their sight as the retina deteriorates. Blindness usually occurs in adulthood.

These problems arise from a mutation that prevents the production of a protein called protocadherin-15, which has a slightly different shape in the ear and eye and is essential for the proper functioning of cells in the auditory and visual systems.

Researchers at Korea’s lab have long been interested in the role of protocadherin-15 in the inner ear. Specifically, they wanted to know how the protein helps sensory receptors called hair cells in the ear convert environmental vibrations into electrical signals that the brain interprets as sound.

Corey’s team previously discovered how protocadherin-15 interacts with another protein called cadherin 23 in hair cells to form filaments that actually open ion channels when the atrioventricular bundles vibrate, allowing electrical current to enter the cells.

In the absence of this protein, electrical current cannot enter the hair cells, vibration cannot be converted to electricity, and the brain cannot pick up sound.

Through this work, Korey became interested in developing a gene therapy for Usher syndrome type 1F.

As a result of the treatment, DNA encoding protocadherin-15 will be delivered to the cell, which will allow the cell to start producing the protein.

However, because protocadherin-15 is so large, its DNA is too large for a typical viral capsule used to transfer genetic material into a cell.

So the researchers decided to explore another option: shortening the DNA to create a small gene that still codes for a functional protein, but small enough to fit in the viral capsule.

Source: Medical Express

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