Audiology in Brief Two proteins that have been implicated in inherited deafness are responsible for building and maintaining stereocilia in the inner ear, according to research in the March 15 Advance Online Publication of Nature Cell Biology. Like high-rise buildings, stereocilia protrude from the tops of inner-ear hair cells and are composed ... News in Brief
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News in Brief  |   May 01, 2009
Audiology in Brief
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Hearing Disorders / News in Brief
News in Brief   |   May 01, 2009
Audiology in Brief
The ASHA Leader, May 2009, Vol. 14, 5. doi:10.1044/leader.NIB.14062009.5
The ASHA Leader, May 2009, Vol. 14, 5. doi:10.1044/leader.NIB.14062009.5
Deafness Linked to Proteins in Stereocilia
Two proteins that have been implicated in inherited deafness are responsible for building and maintaining stereocilia in the inner ear, according to research in the March 15 Advance Online Publication of Nature Cell Biology.
Like high-rise buildings, stereocilia protrude from the tops of inner-ear hair cells and are composed of long filaments of actin. Stereocilia are arranged in tiered bundles, with one bundle topping each hair cell. Tiny filaments connect the shorter stereocilia to their taller neighbors so that, when stimulated by sound, the entire hair bundle moves as a unit.
Stereocilia operate constantly; new actin is added to the tip of the filament and older actin is pushed downward until it reaches the bottom, where it is recycled and added to the tip again. The researchers found that two proteins, myosin IIIa and espin 1, co-localize at the tips of the stereocilia, but are present in a more graded fashion along the length of stereocilium. The myosin IIIa transports espin 1 from the base of the stereocilium to the tip, where espin 1 begins its task of adding more actin to the filament.
These two molecules, which are the product of genes whose mutations result in deafness, seem to be involved in the mechanism to build and maintain stereocilia. Although a mutation in the gene that produces espin 1 results in congenital hearing loss in newborns, mutations in the gene that produces myosin IIIa cause late-onset hearing loss, which can begin in the second decade of life.
Hearing Loss Gene Found
An international team of scientists from the United States, Germany, and France have identified a gene, SLC17A8, that causes a previously unidentified congenital high-frequency hearing loss.
The newly discovered form of hearing loss caused by SLC17A8 is similar to presbycusis, except that it occurs earlier in life, with the degree of hearing loss and the age of onset varying among individuals, according to researcher Marci Lesperance of the University of Michigan Health System.
One direct result of the discovery is that a simple screening for the gene can identify a disposition to the type of hearing loss associated with SLC17A8. Lesperance urged people with relatives who have hearing loss to be aware of the potentially heightened risks to their hearing, to seek frequent hearing screenings, and to avoid exposure to hearing-loss risk factors such as smoking and excessive noise.
Lesperance and her co-researchers hope this gene discovery will lead to new knowledge about presbycusis. An abstract of the study is published in the Aug. 8 issue of The American Journal of Human Genetics.
Teaching Conference
The University of Pittsburgh, Department of Communication Sciences and Disorders, is hosting a conference on the art and science of teaching audiology practice management on June 11–13. The conference provides audiology faculty and clinical instructors an opportunity to discuss best practices in teaching practice management. Conference faculty will provide course handouts, reference lists, take-home assignments, lab exercises, exams, and more. Breakout sessions and poster sessions offer an opportunity to share teaching ideas with colleagues. To submit a poster, send a 250-word abstract to Barbara Vento at barbv@pitt.edu. For more information about the conference, contact Theresa Niecgorski at tmn49@pitt.edu.
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FROM THIS ISSUE
May 2009
Volume 14, Issue 6