Hearing dysfunction in heterozygous MitfMi-wh/+ mice, a model for Waardenburg syndrome type 2 and Tietz syndrome

Authors

  • Christina Ni,

    1. Dermatology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
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  • Deming Zhang,

    1. Dermatology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
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  • Lisa A. Beyer,

    1. Kresge Hearing Research Institute, Department of Otolaryngology, The University of Michigan Medical School, Ann Arbor, MI, USA
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  • Karin E. Halsey,

    1. Kresge Hearing Research Institute, Department of Otolaryngology, The University of Michigan Medical School, Ann Arbor, MI, USA
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  • Hideto Fukui,

    1. Kresge Hearing Research Institute, Department of Otolaryngology, The University of Michigan Medical School, Ann Arbor, MI, USA
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  • Yehoash Raphael,

    1. Kresge Hearing Research Institute, Department of Otolaryngology, The University of Michigan Medical School, Ann Arbor, MI, USA
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  • David F. Dolan,

    1. Kresge Hearing Research Institute, Department of Otolaryngology, The University of Michigan Medical School, Ann Arbor, MI, USA
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  • Thomas J. Hornyak

    Corresponding author
    1. VA Maryland Health Care System, Baltimore, MD, USA
    2. Departments of Dermatology and Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD, USA
    • Dermatology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
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CORRESPONDENCE Thomas J. Hornyak, e-mail: thornyak@som.umaryland.edu

Summary

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 (MitfMi-wh/+) mice were studied and hearing function of these mice characterized. MitfMi-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. MitfMi-wh/+ embryos have fewer melanoblasts during embryonic development than their wild-type littermates. Although cochlear melanocytes are present at birth, they disappear from the MitfMi-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.

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