title: The role of GTF2IRD1 in the auditory pathology of Williams-Beuren Syndrome.
abstract: Williams-Beuren Syndrome (WBS) is a rare genetic condition caused by a hemizygous deletion involving up to 28 genes within chromosome 7q11.23. Among the spectrum of physical and neurological defects in WBS, it is common to find a distinctive response to sound stimuli that includes extreme adverse reactions to loud, or sudden sounds and a fascination with certain sounds that may manifest as strengths in musical ability. However, hearing tests indicate that sensorineural hearing loss (SNHL) is frequently found in WBS patients. The functional and genetic basis of this unusual auditory phenotype is currently unknown. Here, we investigated the potential involvement of GTF2IRD1, a transcription factor encoded by a gene located within the WBS deletion that has been implicated as a contributor to the WBS assorted neurocognitive profile and craniofacial abnormalities. Using Gtf2ird1 knockout mice, we have analysed the expression of the gene in the inner ear and examined hearing capacity by evaluating the auditory brainstem response (ABR) and the distortion product of otoacoustic emissions (DPOAE). Our results show that Gtf2ird1 is expressed in a number of cell types within the cochlea, and Gtf2ird1 null mice showed higher auditory thresholds (hypoacusis) in both ABR and DPOAE hearing assessments. These data indicate that the principal hearing deficit in the mice can be traced to impairments in the amplification process mediated by the outer hair cells and suggests that similar mechanisms may underpin the SNHL experienced by WBS patients.
authors.affiliation: Cellular and Genetic Medicine Unit, School of Medical Sciences, UNSW Australia, Sydney, NSW, Australia.
authors.forename: Cesar P
authors.initials: CP
authors.lastname: Canales
authors.affiliation: Translational Neuroscience Facility, Department of Physiology, School of Medical Sciences, UNSW Australia, Sydney, NWS, Australia.
authors.forename: Ann C Y
authors.initials: AC
authors.lastname: Wong
authors.affiliation: Cellular and Genetic Medicine Unit, School of Medical Sciences, UNSW Australia, Sydney, NSW, Australia.
authors.forename: Peter W
authors.initials: PW
authors.lastname: Gunning
authors.affiliation: Translational Neuroscience Facility, Department of Physiology, School of Medical Sciences, UNSW Australia, Sydney, NWS, Australia.
authors.forename: Gary D
authors.initials: GD
authors.lastname: Housley
authors.affiliation: Cellular and Genetic Medicine Unit, School of Medical Sciences, UNSW Australia, Sydney, NSW, Australia.
authors.forename: Edna C
authors.initials: EC
authors.lastname: Hardeman
authors.affiliation: Cellular and Genetic Medicine Unit, School of Medical Sciences, UNSW Australia, Sydney, NSW, Australia.
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Palmer
mesh_terms: D000818:Animals; D001309:Auditory Threshold; D003051:Cochlea / Q000166:cytology / Q000378:metabolism / Q000502:physiology; D016057:Evoked Potentials, Auditory, Brain Stem; D051379:Mice; D008810:Mice, Inbred C57BL; D009124:Muscle Proteins / Q000235:genetics* / Q000378:metabolism; D009687:Nuclear Proteins / Q000235:genetics* / Q000378:metabolism; D017084:Otoacoustic Emissions, Spontaneous; D015534:Trans-Activators / Q000235:genetics* / Q000378:metabolism; D018980:Williams Syndrome / Q000235:genetics* / Q000503:physiopathology
chemical_list: C486558:Gtf2ird1 protein, mouse; D009124:Muscle Proteins; D009687:Nuclear Proteins; D015534:Trans-Activators