title: Hearing dysfunction in heterozygous Mitf(Mi-wh) /+ mice, a model for Waardenburg syndrome type 2 and Tietz syndrome.
abstract: The human deafness-pigmentation syndromes, Waardenburg syndrome (WS) type 2a, and Tietz syndrome are characterized by profound deafness but only partial cutaneous pigmentary abnormalities. Both syndromes are caused by mutations in MITF. To illuminate differences between cutaneous and otic melanocytes in these syndromes, their development and survival in heterozygous Microphthalmia-White (Mitf(Mi-wh) /+) mice were studied and hearing function of these mice characterized. Mitf(Mi-wh) /+ mice have a profound hearing deficit, characterized by elevated auditory brainstem response thresholds, reduced distortion product otoacoustic emissions, absent endocochlear potential, loss of outer hair cells, and stria vascularis abnormalities. Mitf(Mi-wh) /+ embryos have fewer melanoblasts during embryonic development than their wild-type littermates. Although cochlear melanocytes are present at birth, they disappear from the Mitf(Mi-wh) /+ cochlea between P1 and P7. These findings may provide insight into the mechanism of melanocyte and hearing loss in human deafness-pigmentation syndromes such as WS and Tietz syndrome and illustrate differences between otic and follicular melanocytes.
authors.affiliation: Dermatology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA.
authors.forename: Christina
authors.initials: C
authors.lastname: Ni
authors.forename: Deming
authors.initials: D
authors.lastname: Zhang
authors.forename: Lisa A
authors.initials: LA
authors.lastname: Beyer
authors.forename: Karin E
authors.initials: KE
authors.lastname: Halsey
authors.forename: Hideto
authors.initials: H
authors.lastname: Fukui
authors.forename: Yehoash
authors.initials: Y
authors.lastname: Raphael
authors.forename: David F
authors.initials: DF
authors.lastname: Dolan
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Hornyak
mesh_terms: D000200:Action Potentials / Q000502:physiology; D016115:Albinism, Oculocutaneous / Q000235:genetics / Q000473:pathology / Q000503:physiopathology*; D000818:Animals; D000831:Animals, Newborn; D003638:Deafness / Q000235:genetics / Q000473:pathology / Q000503:physiopathology*; D004195:Disease Models, Animal; D004622:Embryo, Mammalian / Q000378:metabolism / Q000473:pathology; D016057:Evoked Potentials, Auditory, Brain Stem / Q000502:physiology; D018072:Hair Cells, Auditory, Outer / Q000378:metabolism / Q000473:pathology; D006309:Hearing / Q000502:physiology*; D006579:Heterozygote; D006801:Humans; D008544:Melanocytes / Q000378:metabolism / Q000473:pathology; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D051739:Microphthalmia-Associated Transcription Factor / Q000235:genetics*; D017084:Otoacoustic Emissions, Spontaneous / Q000502:physiology; D013316:Stria Vascularis / Q000378:metabolism / Q000473:pathology; D014849:Waardenburg Syndrome / Q000235:genetics / Q000473:pathology / Q000503:physiopathology*
chemical_list: D051739:Microphthalmia-Associated Transcription Factor