Severe hearing loss in Dlxl mutant mice

The Dlx homeobox gene family participates in regulating middle and inner ear development. A significant role for Dlx1, in particular, has been demonstrated in the development of the middle ear ossicles, but the functional consequences of Dlx1 gene mutation on hearing thresholds has not been assessed. The present study characterizes auditory brainstem responses to click and tonal stimuli in a non-lethal variant of a Dlx1 gene knockout. We found that peripheral hearing thresholds for click and tonal stimuli were significantly elevated in homozygous Dlx1 knockout (Dlx1(-/-)) compared to both heterozygous (Dlx1(-/-)) and wild type (Dlx1(+/+)) mice. Thus, abnormal morphogenesis of the incus and stapes that has been documented previously with histological measures is now known to result in a severe peripheral hearing deficit. (c) 2006 Elsevier B.V. All rights reserved.