International Mammalian Genome Society

logo18th International Mouse Genome Conference

17-22 October 2004, Seattle, USA


POSTER 119 - THE HETEROZYGOUS DEAFWADDLER MOUSE IS A MODEL FOR AGE-RELATED HEARING LOSS

McCullough BJ, Tempel BL

University of Wasington, Seattle, United States

Hearing loss is a neurodegenerative disease that affects over 20 million people in this country alone. Recent experiments in our lab indicate that the heterozygous deafwaddler mouse is a model for hearing loss. This phenotype is the result of loss or dysfunction in the plasma membrane calcium ATPase isoform 2 (PMCA2), which is critical for calcium extrusion in the stereocilia of hair cells in the organ of Corti. Mice homozygous for a mutation in the gene encoding this protein are profoundly deaf and ataxic; heterozygotes display partial hearing loss in a haplo-insufficient manner. In young animals, this hearing loss is as great as ~50 dB at high frequencies, while leaving low frequencies largely unaffected. To better characterize the hearing loss seen in these animals, we have genetically manipulated the amount of PMCA2 activity available and examined the progression of hearing loss over time. Preliminary results demonstrate that hearing loss progresses to include lower frequencies with age. Furthermore, the rate of this progression depends on the amount of PMCA2 activity present. This pattern of hearing loss resembles the age-related hearing loss (AHL), or presbycusis, seen in humans and suggests a mechanism involving the cochlear amplifier.

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