MGI:1861630Homozygotes for a spontaneous mutation exhibit short and thin cochlear hair cell stereocilia, progressive degeneration of cochlear and vestibular hair cells, severe deafness, vestibular dysfunction, and poor mothering ability. Homozygotes lacking the long isoform show loss of staircase organization in extrastriolar vestibular hair bundles and thin vestibular stereocilia but no vestibular or hearing deficits.