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Mouse Models of Human Pathogenic Variants of TBC1D24 Associated with Non-Syndromic Deafness DFNB86 and DFNA65 and Syndromes Involving Deafness

1
Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, Porter Neuroscience Research Center, National Institutes of Health, Bethesda, MD 20892, USA
2
The NIDCD National Temporal Laboratory at UCLA, Department of Head and Neck Surgery, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
3
Laboratory of Molecular & Cellular Neurobiology, National Institute of Mental Health, National Institutes of Health, Bethesda, MD 20892, USA
4
Research Center for Genetic Medicine, Children’s National Hospital, Washington, DC 20010, USA
5
Department of Genomics and Precision Medicine, The George Washington University, Washington, DC 20052, USA
6
National Centre of Excellence in Molecular Biology, University of the Punjab Lahore, Lahore 53700, Pakistan
7
Department of Molecular Biology, Shaheed Zulfiqar Ali Bhutto Medical University, Islamabad 44080, Pakistan
8
Jinnah Burn and Reconstructive Surgery Center, Allama Iqbal Medical Research Center, Jinnah Hospital, University of Health Sciences, Lahore 54550, Pakistan
9
Genomics and Computational Biology Core, National Institute on Deafness and Other Communication Disorders, NIH, Bethesda, MD 20892, USA
10
Auditory Development and Restoration Program, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD 20892, USA
11
Genetic Engineering Core, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA
*
Author to whom correspondence should be addressed.
Genes 2020, 11(10), 1122; https://doi.org/10.3390/genes11101122
Received: 3 September 2020 / Revised: 16 September 2020 / Accepted: 21 September 2020 / Published: 24 September 2020
(This article belongs to the Special Issue Genetics of Hearing Impairment)
Human pathogenic variants of TBC1D24 are associated with clinically heterogeneous phenotypes, including recessive nonsyndromic deafness DFNB86, dominant nonsyndromic deafness DFNA65, seizure accompanied by deafness, a variety of isolated seizure phenotypes and DOORS syndrome, characterized by deafness, onychodystrophy, osteodystrophy, intellectual disability and seizures. Thirty-five pathogenic variants of human TBC1D24 associated with deafness have been reported. However, functions of TBC1D24 in the inner ear and the pathophysiology of TBC1D24-related deafness are unknown. In this study, a novel splice-site variant of TBC1D24 c.965 + 1G > A in compound heterozygosity with c.641G > A p.(Arg214His) was found to be segregating in a Pakistani family. Affected individuals exhibited, either a deafness-seizure syndrome or nonsyndromic deafness. In human temporal bones, TBC1D24 immunolocalized in hair cells and spiral ganglion neurons, whereas in mouse cochlea, Tbc1d24 expression was detected only in spiral ganglion neurons. We engineered mouse models of DFNB86 p.(Asp70Tyr) and DFNA65 p.(Ser178Leu) nonsyndromic deafness and syndromic forms of deafness p.(His336Glnfs*12) that have the same pathogenic variants that were reported for human TBC1D24. Unexpectedly, no auditory dysfunction was detected in Tbc1d24 mutant mice, although homozygosity for some of the variants caused seizures or lethality. We provide some insightful supporting data to explain the phenotypic differences resulting from equivalent pathogenic variants of mouse Tbc1d24 and human TBC1D24. View Full-Text
Keywords: Tbc1d24 mouse models; hearing loss; DFNB86; DFNA65; DOORS; syndromic deafness; human temporal bone Tbc1d24 mouse models; hearing loss; DFNB86; DFNA65; DOORS; syndromic deafness; human temporal bone
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Tona, R.; Lopez, I.A.; Fenollar-Ferrer, C.; Faridi, R.; Anselmi, C.; Khan, A.A.; Shahzad, M.; Morell, R.J.; Gu, S.; Hoa, M.; Dong, L.; Ishiyama, A.; Belyantseva, I.A.; Riazuddin, S.; Friedman, T.B. Mouse Models of Human Pathogenic Variants of TBC1D24 Associated with Non-Syndromic Deafness DFNB86 and DFNA65 and Syndromes Involving Deafness. Genes 2020, 11, 1122.

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