Mutant Mouse Gene Offers Clues to Hearing Loss

Variant prevented ear hair cells from pumping out excess calcium, study finds

FRIDAY, Oct. 31, 2008 (HealthDay News) -- A mutation in mice that mimics progressive hearing loss in humans has been identified by European researchers.

They found that mice with a mutation in a gene called Oblivion had problems with the function of hair cells in the inner ear. In mice with one mutant copy of the Oblivion gene, ear hair cells showed some initial function but later degenerated. In mice with two mutant copies of the gene, the ear hair cells were damaged at birth.

"When we mapped the mutation to the mouse genome, we quickly found a probable cause for hearing loss," study senior author Karen Steel, of the Wellcome Trust Sanger Institute in Cambridge, U.K., said in an institute news release.

"We showed that the mutant mice carried a change in one letter of their genetic code in a gene called Atp2b2. Changing a specific C to a T in this gene stops it from producing a normal molecular pump that is needed to keep hair cells in the ear working efficiently by pumping excess calcium out of the cell."

The study was published online Oct. 31 in PLoS Genetics.

Other mutations have been identified, but the Oblivion gene mutation is unique in the way it causes hearing loss due to mutations in Atp2b2, a gene that's previously been linked to hearing loss in humans.

"Our aim of identifying and characterizing mice with impaired hearing is to help us to understand the biology of this remarkable sense," Steel said. "Improving our understanding of the molecular and cellular action of genetic variants will help us to develop improved diagnostics and improved treatments for humans."

Progressive hearing loss affects about 60 percent of people over age 70. Environmental causes can contribute to this hearing loss, but genetics also play a major role.

More information

The National Institute on Deafness and Other Communication Disorders has more about hearing loss.

SOURCE: PLoS Genetics, news release, Oct. 30, 2008
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