Cause of one form of deafness found

CHAMPAIGN, Ill., Feb. 6 (UPI) -- U.S. scientists exploring the physics of hearing say they have found an underlying molecular cause for one form of deafness.

The University of Illinois researchers said within the cochlea of the inner ear, sound waves cause the basilar membrane to vibrate. Those vibrations stimulate hair cells, which trigger nerve impulses transmitted to the brain.

Researchers found mutations in a protein called espin can cause floppiness in tiny bundles of protein filaments, impairing the passage of vibrations and resulting in deafness.

"We found the structure of the bundles changes dramatically when normal espin is replaced with espin mutants that cause deafness," said Professor Gerard Wong. "The interior structure of the bundles changes from a rigid, hexagonal array of uniformly twisted filaments, to a liquid crystalline arrangement of filaments. ... The rigidity of these bundles is essential for hearing."

Wong and his co-authors -- UI postdoctoral research associate Kirstin Purdy and Northwestern University Professor James Bartles -- report their findings in a paper accepted for publication in the journal Physical Review Letters, and posted on its Web site.