New York, Jun 29 (IANS): Scientists have developed a drug that could partially restore hearing in patients with an inherited form of progressive deafness.

"We were able to partially restore hearing, especially at lower frequencies, and save some sensory hair cells," said Thomas B. Friedman from the National Institute on Deafness and Other Communication Disorders (NIDCD), National Institutes of Health in the US.

A decade ago, the researchers found that the deafness-causing mutation LMG2 was in a region on chromosome four called DFNA27, which includes a dozen or so genes, but they were not able to find the exact location.

In the study, published in the journal Cell, a team from the University of Iowa in the US, found a gene known as RE1 Silencing Transcription Factor or Rest gene -- a gene in mice that is regulated through sensory cells of the inner ear which is critical for hearing in mice.

As the human counterpart of the mouse Rest gene is located in the DFNA27 region, the researchers teamed up to re-examine the mystery of DFNA27 progressive deafness.

When the team deleted exon 4 of Rest in mice, inner ear hair cells died, and mice became deaf. Many genes that should have been active were shut off in hair cells prior to their death.

"We found that incorporating exon 4 into the REST mRNA acts like a switch in sensory hair cells. It turns off REST and allows many genes to be turned on. Some of these turned-on genes are important for hair cell survival and hearing," said Botond Banfi from the varsity.

"If additional studies show that small-molecule-based drugs are effective in treating DFNA27 deafness in people, it is possible that using similar approaches might work for other inherited forms of progressive hearing loss," Friedman added.

"By following these genetic leads, we find novel and unexpected pathways that can, in cases such as this one, uncover unexpected potential treatment strategies in humans," the researchers noted.