Expression studies of osteoglycin/mimecan (OGN) in the cochlea and auditory phenotype of Ogn-deficient mice

Genes involved in the hearing process have been identified through both positional cloning efforts following genetic linkage studies of families with heritable deafness and by candidate gene approaches based on known functional properties or inner ear expression. The latter method of gene discovery may employ a tissue- or organ-specific approach. Through characterization of a human fetal cochlear cDNA library, we have identified transcripts that are preferentially and/or highly expressed in the cochlea. High expression in the cochlea may be suggestive of a fundamental role for a transcript in the auditory system. Herein we report the identification and characterization of a transcript from the cochlear cDNA library with abundant cochlear expression and unknown function that was subsequently determined to represent osteoglycin (OGN). Ogn-deficient mice, when analyzed by auditory brainstem response and distortion product otoacoustic emissions, have normal hearing thresholds.