Genetic Treatment of Human Deafness Through Mouse Ear

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Scientific researchers in St. Louis at Washington University School of Medicine had come to a conclusion the genes needed to develop the inner part of the mouse’s ear are suitable to cure human deafness. FGF20, the gene detected for curing human deafness, remain placed in a part of genome that might have links with even healthy families that have symptoms of hereditary deafness.

“When we inactivated FGF20 in mice, we saw they were alive and healthy,” says senior author David M. Ornitz, MD, PhD, the Alumni Endowed Professor of Developmental Biology. “But then we figured out that they had absolutely no ability to hear.”

The reports published in Biological news journals revealed that the disabled genes in the inner ear of mice disconnected several sensitive hair cells that are used to intensify the sound. Most of these outer hair cells, used to transmit the sound to its brain, were not present in the mice having disconnected FGF20 genes, though other hair cells in the inner ear remained unchanged.


“This is the first evidence that inner and outer hair cells develop independently of one another,” says first author Sung-Ho Huh, PhD, postdoctoral research associate. “This is important because most age-related and noise-induced hearing loss is due to the loss of outer hair cells.”

In this way, Huh and Ornitz concluded that the mammals that are deprived from restoring hearing facility need to reproduce the outer hair cells for restoring the hearing system must have FGF20 genes to produce signals of sound.  According to scientists all the vertebra including birds, except mammals, can reproduce outer hair cells to restore their hearing power and they found it interesting to study about this difference.

Only one member of Protein family called fibroblast is needed to match with the requirements of FGF20, though proteins are extensively used for development of embryos, maintaining tissues and healing the wounds. The scientists detected that the signals from FGF20 should be produced in a normal inner ear by the 14th day of the development of embryo otherwise it is underdeveloped if the signaling is late.

“In mice, the precursor cells that can become outer hair cells must be exposed to the FGF20 protein at an early stage,” Ornitz says. “After embryonic day 14, it doesn’t matter if they see the protein. It’s too late for them to become outer hair cells.”

Thus, it is proved through scientific researches that FGF20, found in mice, play vitally in removing human deafness as they necessarily come in contact to outer hair cells to reproduce sound properly.




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