Characterization of hearing in an X,0 ‘Turner mouse’

Abstract

Turner’s syndrome is due to total (45,X) or partial (mosaicism) loss of one X-chromosome. The main features are short stature, ovarian dysgenesis with no estrogen production and infertility. In addition to ear and hearing disorders, middle ear problems including acute/serous otitis media and chronic middle ear disease are frequent. Sensorineural hearing loss is often seen with a dip in the mid-frequencies and also an early high frequency loss. In this study, middle-and inner-ear pathology was characterized using physiological and morphological techniques in a ‘Turner mouse’ that has been generated with the chromosomal aberration X,0. Otitis media was found in some of these X,0 animals, a symptom that is seldom found in control animals. The auditory brainstem responses (ABR) of the Turner mouse showed a progressive hearing loss in the high frequency region that exceeded the normal age-related hearing loss of control mice and increased latencies of the first ABR wave. Outer hair cell loss was apparent in the cochlear basal turn of Turner mice. Decreases in the amplitude of distortion product otoacoustic emissions were correlated with the loss of ABR threshold sensitivity. These results indicate that hearing problems in the Turner mouse seems to be of cochlear origin with an eighth nerve component. This Turner mouse model appears to have ear and hearing problems quite similar to humans and can therefore be used as a model to determine the auditory pathology underlying this syndrome.