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Shadab M, Abbasi AA, Ejaz A, Ben-Mahmoud A, Gupta V, Kim HG, Vona B. Autosomal recessive non-syndromic hearing loss genes in Pakistan during the previous three decades. J Cell Mol Med 2024; 28:e18119. [PMID: 38534090 DOI: 10.1111/jcmm.18119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2023] [Revised: 11/29/2023] [Accepted: 01/02/2024] [Indexed: 03/28/2024] Open
Abstract
Hearing loss is a clinically and genetically heterogeneous disorder, with over 148 genes and 170 loci associated with its pathogenesis. The spectrum and frequency of causal variants vary across different genetic ancestries and are more prevalent in populations that practice consanguineous marriages. Pakistan has a rich history of autosomal recessive gene discovery related to non-syndromic hearing loss. Since the first linkage analysis with a Pakistani family that led to the mapping of the DFNB1 locus on chromosome 13, 51 genes associated with this disorder have been identified in this population. Among these, 13 of the most prevalent genes, namely CDH23, CIB2, CLDN14, GJB2, HGF, MARVELD2, MYO7A, MYO15A, MSRB3, OTOF, SLC26A4, TMC1 and TMPRSS3, account for more than half of all cases of profound hearing loss, while the prevalence of other genes is less than 2% individually. In this review, we discuss the most common autosomal recessive non-syndromic hearing loss genes in Pakistani individuals as well as the genetic mapping and sequencing approaches used to discover them. Furthermore, we identified enriched gene ontology terms and common pathways involved in these 51 autosomal recessive non-syndromic hearing loss genes to gain a better understanding of the underlying mechanisms. Establishing a molecular understanding of the disorder may aid in reducing its future prevalence by enabling timely diagnostics and genetic counselling, leading to more effective clinical management and treatments of hearing loss.
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Affiliation(s)
- Madiha Shadab
- Department of Zoology, Mirpur University of Science and Technology, Mirpur, Pakistan
| | - Ansar Ahmed Abbasi
- Department of Zoology, Mirpur University of Science and Technology, Mirpur, Pakistan
| | - Ahsan Ejaz
- Department of Physics, University of Kotli Azad Jammu and Kashmir, Kotli, Pakistan
- School of Nuclear Science and Technology, Lanzhou University, Lanzhou, China
| | - Afif Ben-Mahmoud
- Neurological Disorders Research Center, Qatar Biomedical Research Institute, Hamad Bin Khalifa University, Doha, Qatar
| | - Vijay Gupta
- Neurological Disorders Research Center, Qatar Biomedical Research Institute, Hamad Bin Khalifa University, Doha, Qatar
| | - Hyung-Goo Kim
- Neurological Disorders Research Center, Qatar Biomedical Research Institute, Hamad Bin Khalifa University, Doha, Qatar
- College of Health & Life Sciences, Hamad Bin Khalifa University (HBKU), Doha, Qatar
| | - Barbara Vona
- Institute of Human Genetics, University Medical Center Göttingen, Göttingen, Germany
- Institute for Auditory Neuroscience and Inner Ear Lab, University Medical Center Göttingen, Göttingen, Germany
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Lei P, Zhu Q, Dong W. Investigation of a novel TBC1D24 variation causing autosomal dominant non-syndromic hearing loss. Sci Rep 2024; 14:4734. [PMID: 38413761 PMCID: PMC10899226 DOI: 10.1038/s41598-024-55435-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Accepted: 02/23/2024] [Indexed: 02/29/2024] Open
Abstract
Hearing loss is considered one of the most common sensory neurological defects, with approximately 60% of cases attributed to genetic factors. Human pathogenic variants in the TBC1D24 gene are associated with various clinical phenotypes, including dominant nonsyndromic hearing loss DFNA65, characterized by progressive hearing loss after the development of language. This study provides an in-depth analysis of the causative gene and mutations in a family with hereditary deafness. We recruited a three-generation family with autosomal dominant nonsyndromic hearing loss (ADNSHL) and conducted detailed medical histories and relevant examinations. Next-generation sequencing (NGS) was used to identify genetic variants in the proband, which were then validated using Sanger sequencing. Multiple computational software tools were employed to predict the impact of the variant on the function and structure of the TBC1D24 protein. A series of bioinformatics tools were applied to determine the conservation characteristics of the sequence, establish a three-dimensional structural model, and investigate changes in molecular dynamics. A detailed genotype and phenotype analysis were carried out. The family exhibited autosomal dominant, progressive, postlingual, and nonsyndromic sensorineural hearing loss. A novel heterozygous variant, c.1459C>T (p.His487Tyr), in the TBC1D24 gene was identified and confirmed to be associated with the hearing loss phenotype in this family. Conservation analysis revealed high conservation of the amino acid affected by this variant across different species. The mutant protein showed alterations in thermodynamic stability, elasticity, and conformational dynamics. Molecular dynamics simulations indicated changes in RMSD, RMSF, Rg, and SASA of the mutant structure. We computed the onset age of non-syndromic hearing loss associated with mutations in the TBC1D24 gene and identified variations in the hearing progression time and annual threshold deterioration across different frequencies. The identification of a new variant associated with rare autosomal dominant nonsyndromic hereditary hearing loss in this family broadens the range of mutations in the TBC1D24 gene. This variant has the potential to influence the interaction between the TLDc domain and TBC domain, thereby affecting the protein's biological function.
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Affiliation(s)
- Peiliang Lei
- Department of Otolaryngology Head & Neck Surgery, The Second Hospital of Hebei Medical University, Heping West Road No. 215, Shijiazhuang, 050000, Hebei, China
- Department of Otolaryngology Head & Neck Surgery, The Third Hospital of Shijiazhuang, Tiyu South Street No.15, Shijiazhuang, 050011, Hebei, China
| | - Qingwen Zhu
- Department of Otolaryngology Head & Neck Surgery, The Second Hospital of Hebei Medical University, Heping West Road No. 215, Shijiazhuang, 050000, Hebei, China.
| | - Wenrong Dong
- Department of Otolaryngology Head & Neck Surgery, The Third Hospital of Shijiazhuang, Tiyu South Street No.15, Shijiazhuang, 050011, Hebei, China
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Li Y, Ning G, Kang B, Zhu J, Wang XY, Wang Q, Cai T. A novel recessive mutation in OXR1 is identified in patient with hearing loss recapitulated by the knockdown zebrafish. Hum Mol Genet 2023; 32:764-772. [PMID: 36130215 PMCID: PMC10365843 DOI: 10.1093/hmg/ddac229] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Revised: 08/23/2022] [Accepted: 09/03/2022] [Indexed: 11/14/2022] Open
Abstract
Hereditary hearing loss is a highly genetically heterogeneous disorder. More than 150 genes have been identified to link to human non-syndromic hearing impairment. To identify genetic mutations and underlying molecular mechanisms in affected individuals and families with congenital hearing loss, we recruited a cohort of 389 affected individuals in 354 families for whole-exome sequencing analysis. In this study, we report a novel homozygous missense variant (c.233A > G, p.Lys78Arg) in the OXR1 gene, which was identified in a 4-year-old girl with sensorineural hearing loss. OXR1 encodes Oxidation Resistance 1 and is evolutionarily conserved from zebrafish to human. We found that the ortholog oxr1b gene is expressed in the statoacoustic ganglion (SAG, a sensory ganglion of ear) and posterior lateral line ganglion (pLL) in zebrafish. Knockdown of oxr1b in zebrafish resulted in a significant developmental defect of SAG and pLL. This phenotype can be rescued by co-injection of wild-type human OXR1 mRNAs, but not mutant OXR1 (c.233A > G) mRNAs. OXR1-associated pathway analysis revealed that mutations of TBC1D24, a TLDc-domain-containing homolog gene of OXR1, have previously been identified in patients with hearing loss. Interestingly, mutations or knockout of OXR1 interacting molecules such as ATP6V1B1 and ESR1 are also associated with hearing loss in patients or animal models, hinting an important role of OXR1 and associated partners in cochlear development and hearing function.
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Affiliation(s)
- Yuan Li
- Department of Otorhinolaryngology, China-Japan Friendship Hospital, Beijing 1000292, China
| | - Guozhu Ning
- Division of Cell, Developmental and Integrative Biology, School of Medicine, South China University of Technology, Guangzhou 5100063, China
- State Key Laboratory of Membrane Biology, Institute of Zoology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 1001014, China
| | - Baoling Kang
- Bioinformatics Section, Angen Gene Medicine Technology, Beijing 1001765, China
| | - Jinwen Zhu
- Bioinformatics Section, Angen Gene Medicine Technology, Beijing 1001765, China
| | | | - Qiang Wang
- Division of Cell, Developmental and Integrative Biology, School of Medicine, South China University of Technology, Guangzhou 5100063, China
| | - Tao Cai
- Experimental Medicine Section, National Institute of Dental and Craniofacial Research, NIH, Bethesda, MD 208927, USA
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, NIH, Bethesda, MD 20892, USA
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Acharya A, Schrauwen I, Leal SM. Identification of autosomal recessive nonsyndromic hearing impairment genes through the study of consanguineous and non-consanguineous families: past, present, and future. Hum Genet 2022; 141:413-430. [PMID: 34291353 PMCID: PMC10416318 DOI: 10.1007/s00439-021-02309-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Accepted: 06/24/2021] [Indexed: 10/20/2022]
Abstract
Hearing impairment (HI) is one of the most common sensory disabilities with exceptionally high genetic heterogeneity. Of genetic HI cases, 30% are syndromic and 70% are nonsyndromic. For nonsyndromic (NS) HI, 77% of the cases are due to autosomal recessive (AR) inheritance. ARNSHI is usually congenital/prelingual, severe-to-profound, affects all frequencies and is not progressive. Thus far, 73 ARNSHI genes have been identified. Populations with high rates of consanguinity have been crucial in the identification of ARNSHI genes, and 92% (67/73) of these genes were identified in consanguineous families. Recent changes in genomic technologies and analyses have allowed a shift towards ARNSHI gene discovery in outbred populations. The latter is crucial towards understanding the genetic architecture of ARNSHI in diverse and understudied populations. We present an overview of the 73 ARNSHI genes, the methods used to identify them, including next-generation sequencing which revolutionized the field, and new technologies that show great promise in advancing ARNSHI discoveries.
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Affiliation(s)
- Anushree Acharya
- Center for Statistical Genetics, Gertrude H. Sergievsky Center, Columbia University Medical Center, New York, NY, USA
- Department of Neurology, Columbia University Medical Center, New York, NY, USA
| | - Isabelle Schrauwen
- Center for Statistical Genetics, Gertrude H. Sergievsky Center, Columbia University Medical Center, New York, NY, USA
- Department of Neurology, Columbia University Medical Center, New York, NY, USA
| | - Suzanne M Leal
- Center for Statistical Genetics, Gertrude H. Sergievsky Center, Columbia University Medical Center, New York, NY, USA.
- Department of Neurology, Columbia University Medical Center, New York, NY, USA.
- Taub Institute for Alzheimer's Disease and the Aging Brain, Columbia University Medical Center, New York, NY, USA.
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Azadegan-Dehkordi F, Koohiyan M, Hoseini M. An update on autosomal recessive hearing loss and loci involved in it. INDIAN JOURNAL OF OTOLOGY 2022. [DOI: 10.4103/indianjotol.indianjotol_115_21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Naz S. Molecular genetic landscape of hereditary hearing loss in Pakistan. Hum Genet 2021; 141:633-648. [PMID: 34308486 DOI: 10.1007/s00439-021-02320-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Accepted: 07/17/2021] [Indexed: 01/13/2023]
Abstract
Approximately 14.5 million Pakistani individuals have a hearing loss and half of these cases may be due to genetic causes. Though significant progress has been made in uncovering genetic variants for recessively inherited nonsyndromic deafness, Pendred syndrome, and Usher syndromes, the same is not true for dominantly inherited hearing loss, most syndromic cases and deafness with complex inheritance patterns. Variants of 57 genes have been reported to cause nonsyndromic recessive deafness in Pakistan, though most are rare. Variants of just five genes GJB2, HGF, MYO7A, SLC26A4, and TMC1 together explain 57% of profound deafness while those of GJB2, MYO15A, OTOF, SLC26A4, TMC1, and TMPRSS3 account for 47% of moderate to severe hearing loss. In contrast, although variants of at least 39 genes have been implicated in different deafness syndromes, their prevalence in the population and the spectrum of mutations have not been explored. Furthermore, research on genetics of deafness has mostly focused on individuals from the Punjab province and needs to be extended to other regions of Pakistan. Identifying the genes and their variants causing deafness in all ethnic groups is important as it will pinpoint rare as well as recurrent mutations. This information may ultimately help in offering genetic counseling and future treatments.
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Affiliation(s)
- Sadaf Naz
- School of Biological Sciences, University of the Punjab, Quaid-e-Azam Campus, Lahore, 54590, Pakistan.
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Yan J, Zheng Y, Yuan P, Wang S, Han S, Yin J, Peng B, Li Z, Sun Y, He X, Liu W. Novel Host Protein TBC1D16, a GTPase Activating Protein of Rab5C, Inhibits Prototype Foamy Virus Replication. Front Immunol 2021; 12:658660. [PMID: 34367131 PMCID: PMC8339588 DOI: 10.3389/fimmu.2021.658660] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Accepted: 07/08/2021] [Indexed: 11/16/2022] Open
Abstract
Prototype foamy virus (PFV) is a member of the oldest family of retroviruses and maintains lifelong latent infection in the host. The lifelong latent infection of PFV may be maintained by the restriction factors of viral replication in the host. However, the mechanisms involved in PFV latent infection are poorly understood. Here, we found that TBC1D16, a TBC domain-containing protein, is significantly down-regulated after PFV infection. Tre2/Bub2/Cdc16 (TBC) domain-containing proteins function as Rab GTPase-activating proteins (GAPs) and are participates in the progression of some diseases and many signaling pathways. However, whether TBC proteins are involved in PFV replication has not been determined. Here, we found that TBC1D16 is a novel antiviral protein that targets Rab5C to suppress PFV replication. Overexpression TBC1D16 inhibited the transcription and expression of Tas and Gag, and silencing TBC1D16 enhanced the PFV replication. Moreover, the highly conserved amino acid residues R494 and Q531 in the TBC domain of TBC1D16 were essential for inhibiting PFV replication. We also found that TBC1D16 promoted the production of PFV-induced IFN-β and the transcription of downstream genes. These results suggest that TBC1D16 might be the first identified TBC proteins that inhibited PFV replication and the mechanism by which TBC1D16 inhibited PFV replication could provide new insights for PFV latency.
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Affiliation(s)
- Jun Yan
- Hubei Province Key Laboratory of Allergy and Immunology, Department of Immunology, School of Basic Medical Sciences, Wuhan University, Wuhan, China
| | - Yingcheng Zheng
- Hubei Province Key Laboratory of Allergy and Immunology, Department of Immunology, School of Basic Medical Sciences, Wuhan University, Wuhan, China
| | - Peipei Yuan
- Hubei Province Key Laboratory of Allergy and Immunology, Department of Immunology, School of Basic Medical Sciences, Wuhan University, Wuhan, China
- Department of Immunology, School of Basic Medical Sciences, Hubei University of Medicine, Shiyan, China
| | - Shanshan Wang
- Hubei Province Key Laboratory of Allergy and Immunology, Department of Immunology, School of Basic Medical Sciences, Wuhan University, Wuhan, China
| | - Song Han
- Hubei Province Key Laboratory of Allergy and Immunology, Department of Immunology, School of Basic Medical Sciences, Wuhan University, Wuhan, China
| | - Jun Yin
- Hubei Province Key Laboratory of Allergy and Immunology, Department of Immunology, School of Basic Medical Sciences, Wuhan University, Wuhan, China
| | - Biwen Peng
- Hubei Province Key Laboratory of Allergy and Immunology, Department of Immunology, School of Basic Medical Sciences, Wuhan University, Wuhan, China
- Department of Physiology, School of Basic Medical Sciences, Wuhan University, Wuhan, China
| | - Zhi Li
- College of Life Sciences, Shanxi Normal University, Xi’an, China
| | - Yan Sun
- College of Life Sciences, Shanxi Normal University, Xi’an, China
| | - Xiaohua He
- Hubei Province Key Laboratory of Allergy and Immunology, Department of Immunology, School of Basic Medical Sciences, Wuhan University, Wuhan, China
- Department of Pathophysiology, School of Basic Medical Sciences, Wuhan University, Wuhan, China
| | - Wanhong Liu
- Hubei Province Key Laboratory of Allergy and Immunology, Department of Immunology, School of Basic Medical Sciences, Wuhan University, Wuhan, China
- Shenzhen Research Institute, Wuhan University, Shenzhen, China
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Genetic architecture and phenotypic landscape of deafness and onychodystrophy syndromes. Hum Genet 2021; 141:821-838. [PMID: 34232384 DOI: 10.1007/s00439-021-02310-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Accepted: 06/28/2021] [Indexed: 10/20/2022]
Abstract
Deafness and onychodystrophy syndromes are a group of phenotypically overlapping syndromes, which include DDOD syndrome (dominant deafness-onychodystrophy), DOORS syndrome (deafness, onychodystrophy, osteodystrophy, mental retardation and seizures) and Zimmermann-Laband syndrome (gingival hypertrophy, coarse facial features, hypoplasia or aplasia of nails and terminal phalanges, intellectual disability, and hypertrichosis). Pathogenic variants in four genes, ATP6V1B2, TBC1D24, KCNH1 and KCNN3, have been shown to be associated with deafness and onychodystrophy syndromes. ATP6V1B2 encodes a component of the vacuolar H+-ATPase (V-ATPase) and TBC1D24 belongs to GTPase-activating protein, which are all involved in the regulation of membrane trafficking. The overlapping clinical phenotype of TBC1D24- and ATP6V1B2- related diseases and their function with GTPases or ATPases activity indicate that they may have some physiological link. Variants in genes encoding potassium channels KCNH1 or KCNN3, underlying human Zimmermann-Laband syndrome, have only recently been recognized. Although further analysis will be needed, these findings will help to elucidate an understanding of the pathogenesis of these disorders better and will aid in the development of potential therapeutic approaches. In this review, we summarize the latest developments of clinical features and molecular basis that have been reported to be associated with deafness and onychodystrophy disorders and highlight the challenges that may arise in the differential diagnosis.
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Timpanaro T, La Mendola F, Billone S, Nora AD, Collotta A, Sauna A, Salafia S, Falsaperla R. TBC1D24 and Its Related Epileptic Encephalopathy. JOURNAL OF PEDIATRIC NEUROLOGY 2021. [DOI: 10.1055/s-0041-1728645] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Abstract
TBC1D24, mapped to 16p13.3, encodes a protein containing a Tre2/Bub2/Cdc16 (TBC) domain, belonging to the super-family of Rab GTPase activating proteins (Rab-GAP). These proteins regulate various functions, including the regulation of the traffic of the vesicular membrane. Several TBC1D24 mutations have been related to autosomal recessive neurological disorders, including severe developmental encephalopathies with malignant early childhood epilepsy, benign epilepsy, epileptic encephalopathy, and a complex neurological syndrome characterized by deafness, onychodystrophy, bone and neurological degeneration. Mutations of TBC1D24 have also been reported in patients with nonsyndromic deafness with dominant or recessive inheritance. Mechanisms underlying TBC1D24-associated disorders and the functions of TBC1D24 products in the generation of such complex spectrum of diseases remain partly unclear and future studies are needed to clarify this aspect, in order to improve the management of seizures and for the prevention of complication (including death) of newly diagnosed patients affected by TBC1D24-related disorders.
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Affiliation(s)
- Tiziana Timpanaro
- Unit of Rare Diseases of the Nervous System in Childhood, Department of Clinical and Experimental Medicine, Section of Pediatrics and Child Neuropsychiatry, University of Catania, Catania, Italy
| | | | - Sebastiano Billone
- Pediatrics Postgraduate Residency Program, Section of Pediatrics and Child Neuropsychiatry, Department of Clinical and Experimental Medicine, University of Catania, Catania, Italy
| | - Alessandra Di Nora
- Pediatrics Postgraduate Residency Program, Section of Pediatrics and Child Neuropsychiatry, Department of Clinical and Experimental Medicine, University of Catania, Catania, Italy
| | - Ausilia Collotta
- Pediatrics Postgraduate Residency Program, Section of Pediatrics and Child Neuropsychiatry, Department of Clinical and Experimental Medicine, University of Catania, Catania, Italy
| | - Alessandra Sauna
- Pediatrics Postgraduate Residency Program, Section of Pediatrics and Child Neuropsychiatry, Department of Clinical and Experimental Medicine, University of Catania, Catania, Italy
| | | | - Raffaele Falsaperla
- Unit of Pediatrics and Pediatric Emergency, University Hospital “Policlinico Rodolico-San Marco,” Catania, Italy
- Unit of Neonatal Intensive Care and Neonatology, University Hospital “Policlinico Rodolico-San Marco,” Catania, Italy
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TBC1D24 emerges as an important contributor to progressive postlingual dominant hearing loss. Sci Rep 2021; 11:10300. [PMID: 33986365 PMCID: PMC8119487 DOI: 10.1038/s41598-021-89645-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Accepted: 04/29/2021] [Indexed: 11/08/2022] Open
Abstract
Several TBC1D24 variants are causally involved in the development of profound, prelingual hearing loss (HL) and different epilepsy syndromes inherited in an autosomal recessive manner. Only two TBC1D24 pathogenic variants have been linked with postlingual progressive autosomal dominant HL (ADHL). To determine the role of TBC1D24 in the development of ADHL and to characterize the TBC1D24-related ADHL, clinical exome sequencing or targeted multigene (n = 237) panel were performed for probands (n = 102) from multigenerational ADHL families. In four families, TBC1D24-related HL was found based on the identification of three novel, likely pathogenic (c.553G>A, p.Asp185Asn; c.1460A>T, p. His487Leu or c.1461C>G, p.His487Gln) and one known (c.533C>T, p.Ser178Leu) TBC1D24 variant. Functional consequences of these variants were characterized by analyzing the proposed homology models of the human TBC1D24 protein. Variants not only in the TBC (p.Ser178Leu, p.Asp185Asn) but also in the TLDc domain (p.His487Gln, p.His487Leu) are involved in ADHL development, the latter two mutations probably affecting interactions between the domains. Clinically, progressive HL involving mainly mid and high frequencies was observed in the patients (n = 29). The progression of HL was calculated by constructing age-related typical audiograms. TBC1D24-related ADHL originates from the cochlear component of the auditory system, becomes apparent usually in the second decade of life and accounts for approximately 4% of ADHL cases. Given the high genetic heterogeneity of ADHL, TBC1D24 emerges as an important contributor to this type of HL.
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Abstract
PURPOSE OF REVIEW The discovery of new disease-causing genes and availability of next-generation sequencing platforms have both progressed rapidly over the last few years. For the practicing neurologist, this presents an increasingly bewildering array both of potential diagnoses and of means to investigate them. We review the latest newly described genetic conditions associated with dystonia, and also address how the changing landscape of gene discovery and genetic testing can best be approached, from both a research and a clinical perspective. RECENT FINDINGS Several new genetic causes for disorders in which dystonia is a feature have been described in the last 2 years, including ZNF142, GSX2, IRF2BPL, DEGS1, PI4K2A, CAMK4, VPS13D and VAMP2. Dystonia has also been a newly described feature or alternative phenotype of several other genetic conditions, notably for genes classically associated with several forms of epilepsy. The DYT system for classifying genetic dystonias, however, last recognized a new gene discovery (KMT2B) in 2016. SUMMARY Gene discovery for dystonic disorders proceeds rapidly, but a high proportion of cases remain undiagnosed. The proliferation of rare disorders means that it is no longer realistic for clinicians to aim for diagnosis to the level of predicting genotype from phenotype in all cases, but rational and adaptive use of available genetic tests can certainly expedite diagnosis.
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Rentas S, Abou Tayoun A. Utility of droplet digital PCR and NGS-based CNV clinical assays in hearing loss diagnostics: current status and future prospects. Expert Rev Mol Diagn 2021; 21:213-221. [PMID: 33554673 DOI: 10.1080/14737159.2021.1887731] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Introduction: Genetic variants in over 100 genes can cause non-syndromic hearing loss (NSHL). Comprehensive diagnostic testing of these genes requires detecting pathogenic sequence and copy number alterations with economical, scalable and sensitive assays. Here we discuss best practices and effective testing algorithms for hearing-loss-related genes with special emphasis on detection of copy number variants.Areas covered: We review studies that used next-generation sequencing (NGS), chromosomal microarrays, droplet digital PCR (ddPCR), and multiplex ligation-dependent probe amplification (MLPA) for the diagnosis of NSHL. We specifically focus on unique and recurrent copy number changes that affect the GJB2 and STRC genes, two of the most common causes of NSHL.Expert opinion: NGS panels and exome sequencing can detect most pathogenic sequence and copy number variants that cause NSHL; however, GJB2 and STRC currently require additional assays to capture all pathogenic copy number variants. Adoption of genome sequencing may simplify diagnostic workflows, but further investigational studies will be required to evaluate its clinical efficacy.
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Affiliation(s)
- Stefan Rentas
- Department of Pathology and Laboratory Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Ahmad Abou Tayoun
- Al Jalila Genomics Center, Al Jalila Children's Specialty Hospital, Dubai, UAE.,Department of Genetics, Mohammed Bin Rashid University of Medicine and Health Sciences, Dubai, UAE
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Parzefall T, Frohne A, Koenighofer M, Neesen J, Laccone F, Eckl-Dorna J, Waters JJ, Schreiner M, Amr SS, Ashton E, Schoefer C, Gstœttner W, Frei K, Lucas T. A Novel Variant in the TBC1D24 Lipid-Binding Pocket Causes Autosomal Dominant Hearing Loss: Evidence for a Genotype-Phenotype Correlation. Front Cell Neurosci 2020; 14:585669. [PMID: 33281559 PMCID: PMC7689082 DOI: 10.3389/fncel.2020.585669] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Accepted: 10/13/2020] [Indexed: 12/23/2022] Open
Abstract
Background: Hereditary hearing loss is a disorder with high genetic and allelic heterogeneity. Diagnostic screening of candidate genes commonly yields novel variants of unknown clinical significance. TBC1D24 is a pleiotropic gene associated with recessive DOORS syndrome, epileptic encephalopathy, myoclonic epilepsy, and both recessive and dominant hearing impairment. Genotype-phenotype correlations have not been established to date but could facilitate diagnostic variant assessment and elucidation of pathomechanisms. Methods and Results: Whole-exome and gene panel screening identified a novel (c.919A>C; p.Asn307His) causative variant in TBC1D24 in two unrelated Caucasian families with Autosomal dominant (AD) nonsyndromic late-onset hearing loss. Protein modeling on the Drosophila TBC1D24 ortholog Skywalker crystal structure showed close interhelix proximity (6.8Å) between the highly conserved residue p.Asn307 in α18 and the position of the single known pathogenic dominant variation (p.Ser178Leu) in α11 that causes a form of deafness with similar clinical characteristics. Conclusion: Genetic variants affecting two polar hydrophilic residues in neighboring helices of TBC1D24 cause AD nonsyndromic late-onset hearing loss. The spatial proximity of the affected residues suggests the first genotype-phenotype association in TBC1D24-related disorders. Three conserved residues in α18 contribute to the formation of a functionally relevant cationic phosphoinositide binding pocket that regulates synaptic vesicle trafficking which may be involved in the molecular mechanism of disease.
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Affiliation(s)
- Thomas Parzefall
- Department of Otorhinolaryngology, Head and Neck Surgery, Medical University of Vienna, Vienna, Austria
| | - Alexandra Frohne
- Department of Otorhinolaryngology, Head and Neck Surgery, Medical University of Vienna, Vienna, Austria.,Department for Cell and Developmental Biology, Orphan Disease Genetics Group, Center for Anatomy and Cell Biology, Medical University of Vienna, Vienna, Austria
| | - Martin Koenighofer
- Department of Otorhinolaryngology, Head and Neck Surgery, Medical University of Vienna, Vienna, Austria
| | - Juergen Neesen
- Institute of Medical Genetics, Center for Pathobiochemistry and Genetics, Medical University of Vienna, Vienna, Austria
| | - Franco Laccone
- Institute of Medical Genetics, Center for Pathobiochemistry and Genetics, Medical University of Vienna, Vienna, Austria
| | - Julia Eckl-Dorna
- Department of Otorhinolaryngology, Head and Neck Surgery, Medical University of Vienna, Vienna, Austria
| | - Jonathan J Waters
- Rare and Inherited Disease Laboratory, London North Genomic Laboratory Hub, Great Ormond Street Hospital for Children NHS Foundation Trust, London, United Kingdom
| | - Markus Schreiner
- Department of Biomedical Imaging and Image-Guided Therapy, Medical University of Vienna, Vienna, Austria
| | - Sami Samir Amr
- Laboratory for Molecular Medicine, Partners Healthcare Personalized Medicine, Cambridge, MA, United States.,Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, United States
| | - Emma Ashton
- Rare and Inherited Disease Laboratory, London North Genomic Laboratory Hub, Great Ormond Street Hospital for Children NHS Foundation Trust, London, United Kingdom
| | - Christian Schoefer
- Department for Cell and Developmental Biology, Orphan Disease Genetics Group, Center for Anatomy and Cell Biology, Medical University of Vienna, Vienna, Austria
| | - Wolfgang Gstœttner
- Department of Otorhinolaryngology, Head and Neck Surgery, Medical University of Vienna, Vienna, Austria
| | - Klemens Frei
- Department of Otorhinolaryngology, Head and Neck Surgery, Medical University of Vienna, Vienna, Austria
| | - Trevor Lucas
- Department for Cell and Developmental Biology, Orphan Disease Genetics Group, Center for Anatomy and Cell Biology, Medical University of Vienna, Vienna, Austria
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14
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Xiang YB, Xu CY, Xu YZ, Li HZ, Zhou LL, Xu XQ, Chen ZH, Tang SH. Next-generation sequencing identifies rare pathogenic and novel candidate variants in a cohort of Chinese patients with syndromic or nonsyndromic hearing loss. Mol Genet Genomic Med 2020; 8:e1539. [PMID: 33095980 PMCID: PMC7767562 DOI: 10.1002/mgg3.1539] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Revised: 09/27/2020] [Accepted: 10/02/2020] [Indexed: 11/15/2022] Open
Abstract
Background Hearing loss (HL) is a common sensory disorder in humans characterized by extreme clinical and genetic heterogeneity. In recent years, next‐generation sequencing (NGS) technologies have proven to be highly effective and powerful tools for population genetic studies of HL. Here, we analyzed clinical and molecular data from 21 Chinese deaf families who did not have hotspot mutations in the common deafness genes GJB2, SLC26A4, GJB3, and MT‐RNR1. Method Targeted next‐generation sequencing (TGS) of 127 known deafness genes was performed in probands of 12 families, while whole‐exome sequencing (WES) or trio‐WES was used for the remaining nine families. Results Potential pathogenic mutations in a total of 12 deafness genes were identified in 13 probands; the mutations were observed in GJB2, CDH23, EDNRB, MYO15A, OTOA, OTOF, TBC1D24, SALL1, TMC1, TWNK, USH1C, and USH1G, with eight of the identified mutations being novel. Further, a copy number variant (CNV) was detected in one proband with heterozygous deletion of chromosome 4p16.3‐4p15.32. Thus, the total diagnostic rate using NGS in our deafness patients reached 66.67% (14/21). Conclusions These results expand the mutation spectrum of deafness‐causing genes and provide support for the use of NGS detection technologies for routine molecular diagnosis in Chinese deaf populations.
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Affiliation(s)
- Yan-Bao Xiang
- Key Laboratory of Birth Defects, Department of Genetics, Wenzhou Central Hospital, Wenzhou, China
| | - Chen-Yang Xu
- Key Laboratory of Birth Defects, Department of Genetics, Wenzhou Central Hospital, Wenzhou, China
| | - Yun-Zhi Xu
- Key Laboratory of Birth Defects, Department of Genetics, Wenzhou Central Hospital, Wenzhou, China
| | - Huan-Zheng Li
- Key Laboratory of Birth Defects, Department of Genetics, Wenzhou Central Hospital, Wenzhou, China
| | - Li-Li Zhou
- Key Laboratory of Birth Defects, Department of Genetics, Wenzhou Central Hospital, Wenzhou, China
| | - Xue-Qin Xu
- Key Laboratory of Birth Defects, Department of Genetics, Wenzhou Central Hospital, Wenzhou, China
| | - Zi-Hui Chen
- Key laboratory of Medical Genetic, School of Laboratory Medicine and Life Science, Wenzhou Medical University, Wenzhou, China
| | - Shao-Hua Tang
- Key Laboratory of Birth Defects, Department of Genetics, Wenzhou Central Hospital, Wenzhou, China.,Key laboratory of Medical Genetic, School of Laboratory Medicine and Life Science, Wenzhou Medical University, Wenzhou, China
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15
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Zhang N, Hou M, Ma S, Liu Y, Wei W, Chen Z. Novel variants in TBC1D24 associated with epilepsy and deafness: Report of two cases. Int J Dev Neurosci 2020; 81:98-105. [PMID: 33063868 DOI: 10.1002/jdn.10070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Revised: 09/26/2020] [Accepted: 10/09/2020] [Indexed: 11/07/2022] Open
Abstract
PURPOSE To identify the causative variants in two unrelated Chinese patients presenting with epilepsy and deafness. METHODS The two patients underwent a thorough examination, including brain MRI, EEG and metabolic studies. Next-generation sequencing (NGS) was performed on genomic DNA samples from the siblings and parents. Sanger sequencing was used to confirm the variants. RESULTS Gene sequencing revealed that they carried two novel compound heterozygous missense variants of the TBC1D24: c.116 C > T (p.Ala39Val) and c.827 T > C (p.Ile276Thr) in patient 1; c.404 C > T (p.Pro135Leu) and c.679 T > C (p.Arg227Trp) in patient 2. Audiologic examination showed bilateral sensorineural hearing loss in both patients. CONCLUSION We have found novel variants in the TBC1D24 in two Chinese unrelated patients. They result in a rare phenotype, characterized by drug-resistant epilepsy and deafness.
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Affiliation(s)
- Na Zhang
- Pediatric Department, the Affiliated Hospital of Qingdao University, Qingdao, P.R. China
| | - Mei Hou
- Pediatric Department, the Qingdao Women & Children Hospital, Qingdao, P.R. China
| | - Shaochun Ma
- Pediatric Department, the Qingdao Women & Children Hospital, Qingdao, P.R. China
| | - Yedan Liu
- Pediatric Department, the Affiliated Hospital of Qingdao University, Qingdao, P.R. China
| | - Wei Wei
- Kangso Medical Inspection Co., Ltd, Beijing, P.R. China
| | - Zongbo Chen
- Pediatric Department, the Affiliated Hospital of Qingdao University, Qingdao, P.R. China
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16
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Tinker RJ, Burghel GJ, Garg S, Steggall M, Cuvertino S, Banka S. Haploinsufficiency of ATP6V0C possibly underlies 16p13.3 deletions that cause microcephaly, seizures, and neurodevelopmental disorder. Am J Med Genet A 2020; 185:196-202. [PMID: 33090716 DOI: 10.1002/ajmg.a.61905] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Revised: 09/15/2020] [Accepted: 09/19/2020] [Indexed: 12/11/2022]
Abstract
We recently contributed to the description of eight individuals with a novel condition caused by 16p13.3 microdeletions encompassing TBC1D24, ATP6V0C, and PDPK1 and resulting in epilepsy, microcephaly and neurodevelopmental problems. The phenotypic spectrum, the minimum overlapping region and the underlying disease mechanism for this disorder remain to be clarified. Here we report a 3.5-year-old male, with microcephaly, autism spectrum disorder and a de novo 16p13.3 microdeletion. We performed detailed in silico analysis to show that the minimum overlapping region for the condition is ~80Kb encompassing five protein coding genes. Analysis of loss of function constraint metrics, transcript-aware evaluation of the population variants, GeVIR scores, analysis of reported pathogenic point variants, detailed review of the known functions of gene products and their animal models showed that the haploinsufficiency of ATP6V0C likely underlies the phenotype of this condition. Protein-protein interaction network, gene phenology and analysis of topologically associating domain showed that it was unlikely that the disorder has an epistatic or regulatory basis. 16p13.3 deletions encompassing ATP6V0C cause a neurodevelopmental disorder. Our results broaden the phenotypic spectrum of this disorder and clarify the likely underlying disease mechanism for the condition.
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Affiliation(s)
- Rory J Tinker
- Manchester Centre for Genomic Medicine, St. Mary's Hospital, Manchester University Foundation NHS Trust, Manchester, UK
| | - George J Burghel
- Manchester Centre for Genomic Medicine, St. Mary's Hospital, Manchester University Foundation NHS Trust, Manchester, UK
| | - Shruti Garg
- Division of Neuroscience & Experimental Psychology, School of Biological Sciences, University of Manchester, Manchester, UK
- Manchester Academic Health Science Centre, Manchester University NHS Foundation Trust, Greater Manchester Mental Health NHS Trust, Manchester, UK
- Department of Child and Adolescent Psychiatry, Royal Manchester Children's Hospital, Manchester, UK
| | - Maggie Steggall
- Department of Paediatric Medicine, Royal Manchester Children's Hospital, Manchester, UK
| | - Sara Cuvertino
- Division of Evolution and Genomic Sciences, School of Biological Sciences, Faculty of Biology, Medicine, and Health, The University of Manchester, Manchester, UK
- Division of Cell Matrix Biology and Regenerative Medicine, School of Biological Sciences, Faculty of Biology, Medicine, and Health, The University of Manchester, Manchester, UK
| | - Siddharth Banka
- Manchester Centre for Genomic Medicine, St. Mary's Hospital, Manchester University Foundation NHS Trust, Manchester, UK
- Division of Evolution and Genomic Sciences, School of Biological Sciences, Faculty of Biology, Medicine, and Health, The University of Manchester, Manchester, UK
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17
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Mouse Models of Human Pathogenic Variants of TBC1D24 Associated with Non-Syndromic Deafness DFNB86 and DFNA65 and Syndromes Involving Deafness. Genes (Basel) 2020; 11:genes11101122. [PMID: 32987832 PMCID: PMC7598720 DOI: 10.3390/genes11101122] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Revised: 09/16/2020] [Accepted: 09/21/2020] [Indexed: 01/08/2023] Open
Abstract
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.
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18
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Harms FL, Parthasarathy P, Zorndt D, Alawi M, Fuchs S, Halliday BJ, McKeown C, Sampaio H, Radhakrishnan N, Radhakrishnan SK, Gorce M, Navet B, Ziegler A, Sachdev R, Robertson SP, Nampoothiri S, Kutsche K. Biallelic loss-of-function variants in TBC1D2B cause a neurodevelopmental disorder with seizures and gingival overgrowth. Hum Mutat 2020; 41:1645-1661. [PMID: 32623794 DOI: 10.1002/humu.24071] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Revised: 06/08/2020] [Accepted: 06/30/2020] [Indexed: 12/15/2022]
Abstract
The family of Tre2-Bub2-Cdc16 (TBC)-domain containing GTPase activating proteins (RABGAPs) is not only known as key regulatorof RAB GTPase activity but also has GAP-independent functions. Rab GTPases are implicated in membrane trafficking pathways, such as vesicular trafficking. We report biallelic loss-of-function variants in TBC1D2B, encoding a member of the TBC/RABGAP family with yet unknown function, as the underlying cause of cognitive impairment, seizures, and/or gingival overgrowth in three individuals from unrelated families. TBC1D2B messenger RNA amount was drastically reduced, and the protein was absent in fibroblasts of two patients. In immunofluorescence analysis, ectopically expressed TBC1D2B colocalized with vesicles positive for RAB5, a small GTPase orchestrating early endocytic vesicle trafficking. In two independent TBC1D2B CRISPR/Cas9 knockout HeLa cell lines that serve as cellular model of TBC1D2B deficiency, epidermal growth factor internalization was significantly reduced compared with the parental HeLa cell line suggesting a role of TBC1D2B in early endocytosis. Serum deprivation of TBC1D2B-deficient HeLa cell lines caused a decrease in cell viability and an increase in apoptosis. Our data reveal that loss of TBC1D2B causes a neurodevelopmental disorder with gingival overgrowth, possibly by deficits in vesicle trafficking and/or cell survival.
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Affiliation(s)
- Frederike L Harms
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Padmini Parthasarathy
- Department of Women's and Children's Health, Dunedin School of Medicine, University of Otago, Dunedin, New Zealand
| | - Dennis Zorndt
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Malik Alawi
- Bioinformatics Core, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Sigrid Fuchs
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Benjamin J Halliday
- Department of Women's and Children's Health, Dunedin School of Medicine, University of Otago, Dunedin, New Zealand
| | - Colina McKeown
- Centre for Clinical Genetics, Sydney Children's Hospital, Randwick, NSW, Australia
| | - Hugo Sampaio
- Department of Women and Children's Health, University of New South Wales, Randwick Campus, Randwick, NSW, Australia.,Sydney Children's Hospital, Randwick, NSW, Australia
| | - Natasha Radhakrishnan
- Department of Ophthalmology, Amrita Institute of Medical Sciences and Research Centre, Cochin, Kerala, India
| | - Suresh K Radhakrishnan
- Department of Neurology, Amrita Institute of Medical Sciences and Research Centre, Cochin, Kerala, India
| | - Magali Gorce
- Department of Metabolic Disease, Children University Hospital, Toulouse, France
| | - Benjamin Navet
- Department of Biochemistry and Genetics, University Hospital of Angers, Angers, France.,MitoLab, Institut MitoVasc, UMR CNRS6015, INSERM U1083, Angers, France
| | - Alban Ziegler
- Department of Biochemistry and Genetics, University Hospital of Angers, Angers, France.,MitoLab, Institut MitoVasc, UMR CNRS6015, INSERM U1083, Angers, France
| | - Rani Sachdev
- Centre for Clinical Genetics, Sydney Children's Hospital, Randwick, NSW, Australia
| | - Stephen P Robertson
- Department of Women's and Children's Health, Dunedin School of Medicine, University of Otago, Dunedin, New Zealand
| | - Sheela Nampoothiri
- Department of Pediatric Genetics, Amrita Institute of Medical Sciences and Research Centre, Cochin, Kerala, India
| | - Kerstin Kutsche
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
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19
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Novel loss-of-function mutations in COCH cause autosomal recessive nonsyndromic hearing loss. Hum Genet 2020; 139:1565-1574. [PMID: 32562050 DOI: 10.1007/s00439-020-02197-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Accepted: 06/12/2020] [Indexed: 12/12/2022]
Abstract
COCH is the most abundantly expressed gene in the cochlea. Unsurprisingly, mutations in COCH underly hearing loss in mice and humans. Two forms of hearing loss are linked to mutations in COCH, the well-established autosomal dominant nonsyndromic hearing loss, with or without vestibular dysfunction (DFNA9) via a gain-of-function/dominant-negative mechanism, and more recently autosomal recessive nonsyndromic hearing loss (DFNB110) via nonsense variants. Using a combination of targeted gene panels, exome sequencing, and functional studies, we identified four novel pathogenic variants (two nonsense variants, one missense, and one inframe deletion) in COCH as the cause of autosomal recessive hearing loss in a multi-ethnic cohort. To investigate whether the non-truncating variants exert their effect via a loss-of-function mechanism, we used minigene splicing assays. Our data showed both the missense and inframe deletion variants altered RNA splicing by creating an exon splicing silencer and abolishing an exon splicing enhancer, respectively. Both variants create frameshifts and are predicted to result in a null allele. This study confirms the involvement of loss-of-function mutations in COCH in autosomal recessive nonsyndromic hearing loss, expands the mutational landscape of DFNB110 to include coding variants that alter RNA splicing, and highlights the need to investigate the effect of coding variants on RNA splicing.
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20
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Tona R, Chen W, Nakano Y, Reyes LD, Petralia RS, Wang YX, Starost MF, Wafa TT, Morell RJ, Cravedi KD, du Hoffmann J, Miyoshi T, Munasinghe JP, Fitzgerald TS, Chudasama Y, Omori K, Pierpaoli C, Banfi B, Dong L, Belyantseva IA, Friedman TB. The phenotypic landscape of a Tbc1d24 mutant mouse includes convulsive seizures resembling human early infantile epileptic encephalopathy. Hum Mol Genet 2020; 28:1530-1547. [PMID: 30602030 DOI: 10.1093/hmg/ddy445] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2018] [Revised: 12/02/2018] [Accepted: 12/11/2018] [Indexed: 12/19/2022] Open
Abstract
Epilepsy, deafness, onychodystrophy, osteodystrophy and intellectual disability are associated with a spectrum of mutations of human TBC1D24. The mechanisms underlying TBC1D24-associated disorders and the functions of TBC1D24 are not well understood. Using CRISPR-Cas9 genome editing, we engineered a mouse with a premature translation stop codon equivalent to human S324Tfs*3, a recessive mutation of TBC1D24 associated with early infantile epileptic encephalopathy (EIEE). Homozygous S324Tfs*3 mice have normal auditory and vestibular functions but show an abrupt onset of spontaneous seizures at postnatal day 15 recapitulating human EIEE. The S324Tfs*3 variant is located in an alternatively spliced micro-exon encoding six perfectly conserved amino acids incorporated postnatally into TBC1D24 protein due to a micro-exon utilization switch. During embryonic and early postnatal development, S324Tfs*3 homozygotes produce predominantly the shorter wild-type TBC1D24 protein isoform that omits the micro-exon. S324Tfs*3 homozygotes show an abrupt onset of seizures at P15 that correlates with a developmental switch to utilization of the micro-exon. A mouse deficient for alternative splice factor SRRM3 impairs incorporation of the Tbc1d24 micro-exon. Wild-type Tbc1d24 mRNA is abundantly expressed in the hippocampus using RNAscope in situ hybridization. Immunogold electron microscopy using a TBC1D24-specific antibody revealed that TBC1D24 is associated with clathrin-coated vesicles and synapses of hippocampal neurons, suggesting a crucial role of TBC1D24 in vesicle trafficking important for neuronal signal transmission. This is the first characterization of a mouse model of human TBC1D24-associated EIEE that can now be used to screen for antiepileptogenic drugs ameliorating TBCID24 seizure disorders.
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Affiliation(s)
- Risa Tona
- Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, Porter Neuroscience Research Center, National Institutes of Health, Bethesda, MD, USA.,Department of Otolaryngology, Head and Neck Surgery, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Wenqian Chen
- Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, Porter Neuroscience Research Center, National Institutes of Health, Bethesda, MD, USA
| | - Yoko Nakano
- Department of Anatomy and Cell Biology, Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - Laura D Reyes
- Quantitative Medical Imaging Section, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, MD, USA
| | - Ronald S Petralia
- Advanced Imaging Core, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD, USA
| | - Ya-Xian Wang
- Advanced Imaging Core, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD, USA
| | - Matthew F Starost
- Division of Veterinary Resources, National Institutes of Health, Bethesda, MD, USA
| | - Talah T Wafa
- Mouse Auditory Testing Core Facility, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD, USA
| | - Robert J Morell
- Genomics and Computational Biology Core, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD, USA
| | - Kevin D Cravedi
- Rodent Behavioral Core, National Institute of Mental Health, Porter Neuroscience Research Center, National Institutes of Health, Bethesda, MD, USA
| | - Johann du Hoffmann
- Rodent Behavioral Core, National Institute of Mental Health, Porter Neuroscience Research Center, National Institutes of Health, Bethesda, MD, USA
| | - Takushi Miyoshi
- Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, Porter Neuroscience Research Center, National Institutes of Health, Bethesda, MD, USA
| | - Jeeva P Munasinghe
- Mouse Imaging Facility, In vivo NMR Center, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
| | - Tracy S Fitzgerald
- Mouse Auditory Testing Core Facility, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD, USA
| | - Yogita Chudasama
- Rodent Behavioral Core, National Institute of Mental Health, Porter Neuroscience Research Center, National Institutes of Health, Bethesda, MD, USA.,Section on Behavioral Neuroscience, National Institute of Mental Health, Porter Neuroscience Research Center, National Institutes of Health, Bethesda, MD, USA
| | - Koichi Omori
- Department of Otolaryngology, Head and Neck Surgery, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Carlo Pierpaoli
- Quantitative Medical Imaging Section, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, MD, USA
| | - Botond Banfi
- Department of Anatomy and Cell Biology, Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - Lijin Dong
- Genetic Engineering Core, National Eye Institute, National Institutes of Health, Bethesda, MD, USA
| | - Inna A Belyantseva
- Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, Porter Neuroscience Research Center, National Institutes of Health, Bethesda, MD, USA
| | - Thomas B Friedman
- Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, Porter Neuroscience Research Center, National Institutes of Health, Bethesda, MD, USA
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21
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Small fish, big prospects: using zebrafish to unravel the mechanisms of hereditary hearing loss. Hear Res 2020; 397:107906. [PMID: 32063424 DOI: 10.1016/j.heares.2020.107906] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Revised: 01/13/2020] [Accepted: 01/29/2020] [Indexed: 12/16/2022]
Abstract
Over the past decade, advancements in high-throughput sequencing have greatly enhanced our knowledge of the mutational signatures responsible for hereditary hearing loss. In its present state, the field has a largely uncensored view of protein coding changes in a growing number of genes that have been associated with hereditary hearing loss, and many more that have been proposed as candidate genes. Sequencing data can now be generated using methods that have become widespread and affordable. The greatest hurdles facing the field concern functional validation of uncharacterized genes and rapid application to human diseases, including hearing and balance disorders. To date, over 30 hearing-related disease models exist in zebrafish. New genome editing technologies, including CRISPR/Cas9 will accelerate the functional validation of hearing loss genes and variants in zebrafish. Here, we discuss current progress in the field and recent advances in genome editing approaches.
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22
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Glöcklhofer CR, Steinfurt J, Franke G, Hoppmann A, Glantschnig T, Perez-Feliz S, Alter S, Fischer J, Brunner M, Rainer PP, Köttgen A, Bode C, Odening KE. A novel LMNA nonsense mutation causes two distinct phenotypes of cardiomyopathy with high risk of sudden cardiac death in a large five-generation family. Europace 2019; 20:2003-2013. [PMID: 29947763 DOI: 10.1093/europace/euy127] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Accepted: 05/09/2018] [Indexed: 12/19/2022] Open
Abstract
Aims Characterization of the cardiac phenotype associated with the novel LMNA nonsense mutation c.544C>T, p.Q182*, which we have identified in a large five-generation family. Methods and results A family tree was constructed. Clinical data [arrhythmia, syncope, sudden cardiac death (SCD), New York Heart Association (NYHA) class] were collected from living and deceased family members. DNA of 23 living family members was analysed for mutations in LMNA. Additionally, dilated cardiomyopathy multi-gene-panel testing and whole exome sequencing were performed in some family members to identify potential phenotype-modifiers. In this five-generation family (n = 65), 17 SCDs occurred at 49.3 ± 10.0 years. Furthermore, we identified eight additional mutation-carriers, seven symptomatic (44 ± 13 years), and one asymptomatic (44 years). First signs of disease [sinus bradycardia with atrioventricular (AV)-block I°] occurred at 36.5 ± 8.1 years. Paroxysmal atrial fibrillation (AF) (onset at 41.8 ± 5.7 years) rapidly progressed to permanent AF (46.2 ± 9.8 years). Subsequently, AV-conduction worsened, syncope, pacemaker-dependence, and non-sustained ventricular tachycardia (43.3 ± 8.2 years) followed. Ventricular arrhythmia caused SCD in patients without implantable cardioverter-defibrillator (ICD). Patients protected by ICD developed rapidly progressive heart failure (45.2 ± 10.6 years). A different phenotype was seen in a sub-family in three patients with early onset of rapidly decompensating heart failure and only minor prior arrhythmia-related symptoms. One patient received high-urgency heart transplantation (HTX) at 32 years, while two died prior to HTX. One of them developed lethal peripartum-associated heart failure. Possible disease-modifiers were identified in this 'heart failure sub-family'. Conclusion The novel LMNA nonsense mutation c.544C>T causes a severe arrhythmogenic phenotype manifesting with high incidence of SCD in most patients; and in one sub-family, a distinct phenotype with fast progressing heart failure, indicating the need for early consideration of ICD-implantation and listing for heart-transplantation.
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Affiliation(s)
- Christina R Glöcklhofer
- Department of Cardiology and Angiology I, Heart Center University of Freiburg, Hugstetter Str. 55, Freiburg, Germany.,Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Johannes Steinfurt
- Department of Cardiology and Angiology I, Heart Center University of Freiburg, Hugstetter Str. 55, Freiburg, Germany.,Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Gerlind Franke
- Department of Cardiology and Angiology I, Heart Center University of Freiburg, Hugstetter Str. 55, Freiburg, Germany.,Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Anselm Hoppmann
- Faculty of Medicine, University of Freiburg, Freiburg, Germany.,Institute of Genetic Epidemiology, Medical Center University of Freiburg, Freiburg, Germany.,Genetics and Experimental Bioinformatics, Faculty of Biology, University of Freiburg, Freiburg, Germany
| | | | - Stefanie Perez-Feliz
- Department of Cardiology and Angiology I, Heart Center University of Freiburg, Hugstetter Str. 55, Freiburg, Germany.,Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Svenja Alter
- Faculty of Medicine, University of Freiburg, Freiburg, Germany.,Institute of Human Genetics, Medical Center University of Freiburg, Freiburg, Germany
| | - Judith Fischer
- Faculty of Medicine, University of Freiburg, Freiburg, Germany.,Institute of Human Genetics, Medical Center University of Freiburg, Freiburg, Germany
| | - Michael Brunner
- Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Peter P Rainer
- Division of Cardiology, Medical University of Graz, Graz, Austria
| | - Anna Köttgen
- Faculty of Medicine, University of Freiburg, Freiburg, Germany.,Institute of Genetic Epidemiology, Medical Center University of Freiburg, Freiburg, Germany
| | - Christoph Bode
- Department of Cardiology and Angiology I, Heart Center University of Freiburg, Hugstetter Str. 55, Freiburg, Germany.,Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Katja E Odening
- Department of Cardiology and Angiology I, Heart Center University of Freiburg, Hugstetter Str. 55, Freiburg, Germany.,Faculty of Medicine, University of Freiburg, Freiburg, Germany
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23
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D'Aguillo C, Bressler S, Yan D, Mittal R, Fifer R, Blanton SH, Liu X. Genetic screening as an adjunct to universal newborn hearing screening: literature review and implications for non-congenital pre-lingual hearing loss. Int J Audiol 2019; 58:834-850. [PMID: 31264897 DOI: 10.1080/14992027.2019.1632499] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Objective: Universal newborn hearing screening (UNHS) uses otoacoustic emissions testing (OAE) and auditory brainstem response testing (ABR) to screen all newborn infants for hearing loss (HL), but may not identify infants with mild HL at birth or delayed onset HL. The purpose of this review is to examine the role of genetic screening to diagnose children with pre-lingual HL that is not detected at birth by determining the rate of children who pass UNHS but have a positive genetic screening. This includes a summary of the current UNHS and its limitations and a review of genetic mutations and screening technologies used to detect patients with an increased risk of undiagnosed pre-lingual HL.Design: Literature review of studies that compare UNHS with concurrent genetic screening.Study sample: Infants and children with HLResults: Sixteen studies were included encompassing 137,895 infants. Pathogenic mutations were detected in 8.66% of patients. In total, 545 patients passed the UNHS but had a positive genetic screening. The average percentage of patients who passed UNHS but had a positive genetic screening was 1.4%.Conclusions: This review demonstrates the positive impact of concurrent genetic screening with UNHS to identify patients with pre-lingual HL.
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Affiliation(s)
- Christine D'Aguillo
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Sara Bressler
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Denise Yan
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Rahul Mittal
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Robert Fifer
- Department of Pediatrics, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Susan H Blanton
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, FL, USA.,Department of Human Genetics, Dr. John T. Macdonald Foundation, Miami, FL, USA.,John P Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Xuezhong Liu
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, FL, USA.,Department of Pediatrics, University of Miami Miller School of Medicine, Miami, FL, USA.,Department of Human Genetics, Dr. John T. Macdonald Foundation, Miami, FL, USA.,John P Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, FL, USA.,Tsinghua University School of Medicine, Beijing, PR China
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24
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Shearer AE, Hansen MR. Auditory synaptopathy, auditory neuropathy, and cochlear implantation. Laryngoscope Investig Otolaryngol 2019; 4:429-440. [PMID: 31453354 PMCID: PMC6703118 DOI: 10.1002/lio2.288] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Revised: 05/17/2019] [Accepted: 06/13/2019] [Indexed: 02/03/2023] Open
Abstract
Cochlear implantation has become the standard-of-care for adults and children with severe to profound hearing loss. There is growing evidence that qualitative as well as quantitative deficits in the auditory nerve may affect cochlear implant (CI) outcomes. Auditory neuropathy spectrum disorder (ANSD) is characterized by dysfunctional transmission of sound from the cochlea to the brain due to defective synaptic function or neural conduction. In this review, we examine the precise mechanisms of genetic lesions causing ANSD and the effect of these lesions on CI outcomes. Reviewed data show that individuals with lesions that primarily affect the cochlear sensory system and the synapse, which are bypassed by the CI, have optimal CI outcomes. Individuals with lesions that affect the auditory nerve show poor performance with CIs, likely because neural transmission of the electrical signal from the CI is affected. We put forth a nuanced molecular classification of ANSD that has implications for preoperative counseling for patients with this disorder prior to cochlear implantation. We propose that description of ANSD patients should be based on the molecular site of lesion typically derived from genetic evaluation (synaptopathy vs. neuropathy) as this has implications for expected CI outcomes. Improvements in our understanding of genetic site of lesions and their effects on CI function should lead to better CI outcomes, not just for individuals with auditory neuropathy, but all individuals with hearing loss.
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Affiliation(s)
- Aiden Eliot Shearer
- Department of Otolaryngology-Head and Neck Surgery University of Iowa Carver College of Medicine Iowa City Iowa U.S.A
| | - Marlan R Hansen
- Department of Otolaryngology-Head and Neck Surgery University of Iowa Carver College of Medicine Iowa City Iowa U.S.A.,Department of Neurosurgery University of Iowa Carver College of Medicine Iowa City Iowa U.S.A
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25
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Zhang J, Chen J, Zeng Q, Zhang L, Tian X, Yang X, Yang Z, Wu Y, Wu X, Zhang Y. Infantile epilepsy with multifocal myoclonus caused by TBC1D24 mutations. Seizure 2019; 69:228-234. [DOI: 10.1016/j.seizure.2019.05.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2018] [Revised: 05/09/2019] [Accepted: 05/11/2019] [Indexed: 11/16/2022] Open
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26
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Finelli MJ, Aprile D, Castroflorio E, Jeans A, Moschetta M, Chessum L, Degiacomi MT, Grasegger J, Lupien-Meilleur A, Bassett A, Rossignol E, Campeau PM, Bowl MR, Benfenati F, Fassio A, Oliver PL. The epilepsy-associated protein TBC1D24 is required for normal development, survival and vesicle trafficking in mammalian neurons. Hum Mol Genet 2019; 28:584-597. [PMID: 30335140 PMCID: PMC6360273 DOI: 10.1093/hmg/ddy370] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2018] [Accepted: 10/09/2018] [Indexed: 12/16/2022] Open
Abstract
Mutations in the Tre2/Bub2/Cdc16 (TBC)1 domain family member 24 (TBC1D24) gene are associated with a range of inherited neurological disorders, from drug-refractory lethal epileptic encephalopathy and DOORS syndrome (deafness, onychodystrophy, osteodystrophy, mental retardation, seizures) to non-syndromic hearing loss. TBC1D24 has been implicated in neuronal transmission and maturation, although the molecular function of the gene and the cause of the apparently complex disease spectrum remain unclear. Importantly, heterozygous TBC1D24 mutation carriers have also been reported with seizures, suggesting that haploinsufficiency for TBC1D24 is significant clinically. Here we have systematically investigated an allelic series of disease-associated mutations in neurons alongside a new mouse model to investigate the consequences of TBC1D24 haploinsufficiency to mammalian neurodevelopment and synaptic physiology. The cellular studies reveal that disease-causing mutations that disrupt either of the conserved protein domains in TBC1D24 are implicated in neuronal development and survival and are likely acting as loss-of-function alleles. We then further investigated TBC1D24 haploinsufficiency in vivo and demonstrate that TBC1D24 is also crucial for normal presynaptic function: genetic disruption of Tbc1d24 expression in the mouse leads to an impairment of endocytosis and an enlarged endosomal compartment in neurons with a decrease in spontaneous neurotransmission. These data reveal the essential role for TBC1D24 at the mammalian synapse and help to define common synaptic mechanisms that could underlie the varied effects of TBC1D24 mutations in neurological disease.
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Affiliation(s)
- Mattéa J Finelli
- Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, Oxford, UK
| | - Davide Aprile
- Department of Experimental Medicine, University of Genoa, Genoa, Italy
| | - Enrico Castroflorio
- Center of Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, Largo Rosanna Benzi 9, Genoa, Italy
| | - Alexander Jeans
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford, UK
| | - Matteo Moschetta
- Department of Experimental Medicine, University of Genoa, Genoa, Italy.,Center of Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, Largo Rosanna Benzi 9, Genoa, Italy
| | | | | | - Julia Grasegger
- Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, Oxford, UK
| | - Alexis Lupien-Meilleur
- CHU Ste-Justine, Departments of Neurosciences and Pediatrics, Université de Montréal, Montreal, QC, Canada
| | - Andrew Bassett
- Cellular Operations, Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridgeshire, UK
| | - Elsa Rossignol
- CHU Ste-Justine, Departments of Neurosciences and Pediatrics, Université de Montréal, Montreal, QC, Canada
| | - Philippe M Campeau
- CHU Ste-Justine, Departments of Neurosciences and Pediatrics, Université de Montréal, Montreal, QC, Canada
| | | | - Fabio Benfenati
- Center of Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, Largo Rosanna Benzi 9, Genoa, Italy.,IRCCS Ospedale Policlinico San Martino, Largo Rosanna Benzi 10, Genoa, Italy
| | - Anna Fassio
- Department of Experimental Medicine, University of Genoa, Genoa, Italy.,IRCCS Ospedale Policlinico San Martino, Largo Rosanna Benzi 10, Genoa, Italy
| | - Peter L Oliver
- Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, Oxford, UK.,MRC Harwell Institute, Harwell, Oxfordshire, UK
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27
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Aprile D, Fruscione F, Baldassari S, Fadda M, Ferrante D, Falace A, Buhler E, Sartorelli J, Represa A, Baldelli P, Benfenati F, Zara F, Fassio A. TBC1D24 regulates axonal outgrowth and membrane trafficking at the growth cone in rodent and human neurons. Cell Death Differ 2019; 26:2464-2478. [PMID: 30858606 DOI: 10.1038/s41418-019-0313-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2018] [Revised: 01/25/2019] [Accepted: 02/20/2019] [Indexed: 01/04/2023] Open
Abstract
Mutations in TBC1D24 are described in patients with a spectrum of neurological diseases, including mild and severe epilepsies and complex syndromic phenotypes such as Deafness, Onycodystrophy, Osteodystrophy, Mental Retardation and Seizure (DOORS) syndrome. The product of TBC1D24 is a multifunctional protein involved in neuronal development, regulation of synaptic vesicle trafficking, and protection from oxidative stress. Although pathogenic mutations in TBC1D24 span the entire coding sequence, no clear genotype/phenotype correlations have emerged. However most patients bearing predicted loss of function mutations exhibit a severe neurodevelopmental disorder. Aim of the study is to investigate the impact of TBC1D24 knockdown during the first stages of neuronal differentiation when axonal specification and outgrowth take place. In rat cortical primary neurons silenced for TBC1D24, we found defects in axonal specification, the maturation of axonal initial segment and action potential firing. The axonal phenotype was accompanied by an impairment of endocytosis at the growth cone and an altered activation of the TBC1D24 molecular partner ADP ribosylation factor 6. Accordingly, acute knockdown of TBC1D24 in cerebrocortical neurons in vivo analogously impairs callosal projections. The axonal defect was also investigated in human induced pluripotent stem cell-derived neurons from patients carrying TBC1D24 mutations. Reprogrammed neurons from a patient with severe developmental encephalopathy show significant axon formation defect that were absent from reprogrammed neurons of a patient with mild early onset epilepsy. Our data reveal that alterations of membrane trafficking at the growth cone induced by TBC1D24 loss of function cause axonal and excitability defects. The axonal phenotype correlates with the disease severity and highlight an important role for TBC1D24 in connectivity during brain development.
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Affiliation(s)
- Davide Aprile
- Department of Experimental Medicine, University of Genoa, Genoa, Italy
| | - Floriana Fruscione
- Laboratory of Neurogenetics and Neuroscience, IRCCS Istituto Giannina Gaslini, Genoa, Italy
| | - Simona Baldassari
- Laboratory of Neurogenetics and Neuroscience, IRCCS Istituto Giannina Gaslini, Genoa, Italy
| | - Manuela Fadda
- Department of Experimental Medicine, University of Genoa, Genoa, Italy
| | - Daniele Ferrante
- Department of Experimental Medicine, University of Genoa, Genoa, Italy
| | - Antonio Falace
- Pediatric Neurology, Neurogenetics and Neurobiology Unit and Laboratories, Children's Hospital A. Meyer-University of Florence, Florence, Italy
| | | | - Jacopo Sartorelli
- Laboratory of Neurogenetics and Neuroscience, IRCCS Istituto Giannina Gaslini, Genoa, Italy
| | - Alfonso Represa
- INMED, Aix-Marseille University, INSERM U1249, Marseille, France
| | - Pietro Baldelli
- Department of Experimental Medicine, University of Genoa, Genoa, Italy.,IRCCS Ospedale Policlinico San Martino, Genoa, Italy
| | - Fabio Benfenati
- IRCCS Ospedale Policlinico San Martino, Genoa, Italy.,Center of Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, Genoa, Italy
| | - Federico Zara
- Laboratory of Neurogenetics and Neuroscience, IRCCS Istituto Giannina Gaslini, Genoa, Italy
| | - Anna Fassio
- Department of Experimental Medicine, University of Genoa, Genoa, Italy. .,IRCCS Ospedale Policlinico San Martino, Genoa, Italy.
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28
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Santos M, Reis-Rego Â, Coutinho M, Almeida E Sousa C. DOOR syndrome: A case report and its embryological basis. Int J Pediatr Otorhinolaryngol 2019; 117:57-60. [PMID: 30579089 DOI: 10.1016/j.ijporl.2018.11.015] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/19/2018] [Revised: 11/10/2018] [Accepted: 11/10/2018] [Indexed: 11/19/2022]
Abstract
DOOR syndrome is an extremely rare genetic disorder. "DOOR″ is an acronym to describe the combination of: deafness, onychodystrophy, osteodystrophy and mental retardation. We present a patient, with all of the above-mentioned main symptoms, that was rehabilitated with convencional hearing aids. The presented case suggested that every case of deafness and abnormal nails and phalanges in the hands and feet should have a clinical diagnosis of possible DOOR syndrome. Based on embryological process, congenital abnormal nails or phalanges highlights the importance for detailed hearing screening.
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MESH Headings
- Carrier Proteins/genetics
- Child, Preschool
- Craniofacial Abnormalities/complications
- Craniofacial Abnormalities/diagnosis
- Craniofacial Abnormalities/therapy
- Deafness/etiology
- Deafness/therapy
- Evoked Potentials, Auditory
- Female
- GTPase-Activating Proteins
- Hand Deformities, Congenital/complications
- Hand Deformities, Congenital/diagnosis
- Hand Deformities, Congenital/therapy
- Hearing Aids
- Hearing Loss, Sensorineural/complications
- Hearing Loss, Sensorineural/diagnosis
- Hearing Loss, Sensorineural/therapy
- Humans
- Intellectual Disability/complications
- Intellectual Disability/diagnosis
- Intellectual Disability/etiology
- Intellectual Disability/therapy
- Membrane Proteins
- Mutation
- Nails, Malformed/complications
- Nails, Malformed/diagnosis
- Nails, Malformed/etiology
- Nails, Malformed/therapy
- Nerve Tissue Proteins
- Tomography, X-Ray Computed
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29
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Nakashima M, Negishi Y, Hori I, Hattori A, Saitoh S, Saitsu H. A case of early-onset epileptic encephalopathy with a homozygous TBC1D24 variant caused by uniparental isodisomy. Am J Med Genet A 2019; 179:645-649. [PMID: 30680869 DOI: 10.1002/ajmg.a.61056] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2018] [Revised: 12/03/2018] [Accepted: 01/06/2019] [Indexed: 11/11/2022]
Abstract
TBC1D24-related disorders are rare neurodevelopmental disorders that show a broad range of neuropsychiatric deficits and are mostly inherited in an autosomal recessive manner. Here we describe a case with early-onset epileptic encephalopathy, in whom exome sequencing detected a novel pathogenic homozygous c.442G>A, p.(Glu148Lys) variant in TBC1D24. She showed severe developmental delay, congenital sensorineural hearing loss and seizures, but the combination of a high dose phenobarbital and potassium bromide was very effective for the seizures. Sanger sequencing revealed that her mother was a heterozygous carrier of the TBC1D24 variant, but her father showed only wild-type alleles. Homozygosity mapping analysis using exome data showed loss of the heterozygosity region at 16p13.3-p13.13 encompassing TBC1D24. Genotyping analysis using rare variants within loss of the heterozygosity region indicated that the patient has a homozygous haplotype inherited from her mother, indicating maternal segmental uniparental isodisomy (UPiD). These data clearly show that exome sequencing is a powerful tool to perform comprehensive genetic analysis.
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Affiliation(s)
- Mitsuko Nakashima
- Department of Biochemistry, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Yutaka Negishi
- Department of Pediatrics and Neonatology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
| | - Ikumi Hori
- Department of Pediatrics and Neonatology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
| | - Ayako Hattori
- Department of Pediatrics and Neonatology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
| | - Shinji Saitoh
- Department of Pediatrics and Neonatology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
| | - Hirotomo Saitsu
- Department of Biochemistry, Hamamatsu University School of Medicine, Hamamatsu, Japan
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30
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Carpena NT, Lee MY. Genetic Hearing Loss and Gene Therapy. Genomics Inform 2018; 16:e20. [PMID: 30602081 PMCID: PMC6440668 DOI: 10.5808/gi.2018.16.4.e20] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Accepted: 12/04/2018] [Indexed: 12/15/2022] Open
Abstract
Genetic hearing loss crosses almost all the categories of hearing loss which includes the following: conductive, sensory, and neural; syndromic and nonsyndromic; congenital, progressive, and adult onset; high-frequency, low-frequency, or mixed frequency; mild or profound; and recessive, dominant, or sex-linked. Genes play a role in almost half of all cases of hearing loss but effective treatment options are very limited. Genetic hearing loss is considered to be extremely genetically heterogeneous. The advancements in genomics have been instrumental to the identification of more than 6,000 causative variants in more than 150 genes causing hearing loss. Identification of genes for hearing impairment provides an increased insight into the normal development and function of cells in the auditory system. These defective genes will ultimately be important therapeutic targets. However, the auditory system is extremely complex which requires tremendous advances in gene therapy including gene vectors, routes of administration, and therapeutic approaches. This review summarizes and discusses recent advances in elucidating the genomics of genetic hearing loss and technologies aimed at developing a gene therapy that may become a treatment option for in the near future.
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Affiliation(s)
- Nathanial T Carpena
- Department of Otolaryngology-Head and Neck Surgery, Dankook University College of Medicine, Cheonan 31116, Korea
| | - Min Young Lee
- Department of Otolaryngology-Head and Neck Surgery, Dankook University College of Medicine, Cheonan 31116, Korea.,Beckman Laser Institute Korea, Dankook University, Cheonan 31116, Korea
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31
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Danial-Farran N, Brownstein Z, Gulsuner S, Tammer L, Khayat M, Aleme O, Chervinsky E, Zoubi OA, Walsh T, Ast G, King MC, Avraham KB, Shalev SA. Genetics of hearing loss in the Arab population of Northern Israel. Eur J Hum Genet 2018; 26:1840-1847. [PMID: 30139988 PMCID: PMC6244407 DOI: 10.1038/s41431-018-0218-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2018] [Revised: 06/18/2018] [Accepted: 06/26/2018] [Indexed: 01/04/2023] Open
Abstract
For multiple generations, much of the Arab population of Northern Israel has lived in communities with consanguineous marriages and large families. These communities have been particularly cooperative and informative for understanding the genetics of recessive traits. We studied the genetics of hearing loss in this population, evaluating 168 families from 46 different villages. All families were screened for founder variants by Sanger sequencing and 13 families were further evaluated by sequencing all known genes for hearing loss using our targeted gene panel HEar-Seq. Deafness in 34 of 168 families (20%) was explained by founder variants in GJB2, SLC26A4, or OTOF. In 6 of 13 families (46%) evaluated using HEar-Seq, deafness was explained by damaging alleles of SLC26A4, MYO15A, OTOG, LOXHD1, and TBC1D24. In some genes critical to hearing, it is particularly difficult to interpret variants that might affect splicing, because the genes are not expressed in accessible tissue. To address this problem for possible splice-altering variants of MYO15A, we evaluated minigenes transfected into HEK293 cells. Results revealed exon skipping in the message of MYO15A c.9083+6T>A, and intron retention in the message of MYO15A c.8340G>A, in each case leading to a premature stop and consistent with co-segregation of homozygosity for each variant with hearing loss. The profile of genetics of hearing loss in this population reflects the genetic heterogeneity of hearing loss and the usefulness of synthetic technologies to evaluate potentially causal variants in genes not expressed in accessible tissues.
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Affiliation(s)
- Nada Danial-Farran
- Genetics Institute, Emek Medical Center, Afula, Israel.,Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel.,Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
| | - Zippora Brownstein
- Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
| | - Suleyman Gulsuner
- Department of Medicine, Division of Medical Genetics, University of Washington, Seattle, WA, USA
| | - Luna Tammer
- Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
| | - Morad Khayat
- Genetics Institute, Emek Medical Center, Afula, Israel
| | - Ola Aleme
- Genetics Institute, Emek Medical Center, Afula, Israel
| | | | | | - Tom Walsh
- Department of Medicine, Division of Medical Genetics, University of Washington, Seattle, WA, USA
| | - Gil Ast
- Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
| | - Mary-Claire King
- Department of Medicine, Division of Medical Genetics, University of Washington, Seattle, WA, USA
| | - Karen B Avraham
- Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel.
| | - Stavit A Shalev
- Genetics Institute, Emek Medical Center, Afula, Israel. .,Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel.
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32
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DiStefano MT, Hemphill SE, Cushman BJ, Bowser MJ, Hynes E, Grant AR, Siegert RK, Oza AM, Gonzalez MA, Amr SS, Rehm HL, Abou Tayoun AN. Curating Clinically Relevant Transcripts for the Interpretation of Sequence Variants. J Mol Diagn 2018; 20:789-801. [PMID: 30096381 DOI: 10.1016/j.jmoldx.2018.06.005] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2018] [Revised: 05/20/2018] [Accepted: 06/19/2018] [Indexed: 10/28/2022] Open
Abstract
Variant interpretation depends on accurate annotations using biologically relevant transcripts. We have developed a systematic strategy for designating primary transcripts and have applied it to 109 hearing loss-associated genes that were divided into three categories. Category 1 genes (n = 38) had a single transcript; category 2 genes (n = 33) had multiple transcripts, but a single transcript was sufficient to represent all exons; and category 3 genes (n = 38) had multiple transcripts with unique exons. Transcripts were curated with respect to gene expression reported in the literature and the Genotype-Tissue Expression Project. In addition, high-frequency loss-of-function variants in the Genome Aggregation Database and disease-causing variants in ClinVar and the Human Gene Mutation Database across the 109 genes were queried. These data were used to classify exons as clinically significant, insignificant, or of uncertain significance. Interestingly, 6% of all exons, containing 124 reportedly disease-causing variants, were of uncertain significance. Finally, we used exon-level next-generation sequencing quality metrics generated at two clinical laboratories and identified a total of 43 technically challenging exons in 20 different genes that had inadequate coverage and/or homology issues that might lead to false-variant calls. We have demonstrated that transcript analysis plays a critical role in accurate clinical variant interpretation.
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Affiliation(s)
- Marina T DiStefano
- Laboratory for Molecular Medicine, Partners Healthcare Personalized Medicine, Cambridge, Massachusetts
| | - Sarah E Hemphill
- Laboratory for Molecular Medicine, Partners Healthcare Personalized Medicine, Cambridge, Massachusetts
| | - Brandon J Cushman
- Laboratory for Molecular Medicine, Partners Healthcare Personalized Medicine, Cambridge, Massachusetts
| | - Mark J Bowser
- Laboratory for Molecular Medicine, Partners Healthcare Personalized Medicine, Cambridge, Massachusetts
| | - Elizabeth Hynes
- Laboratory for Molecular Medicine, Partners Healthcare Personalized Medicine, Cambridge, Massachusetts
| | - Andrew R Grant
- Laboratory for Molecular Medicine, Partners Healthcare Personalized Medicine, Cambridge, Massachusetts
| | - Rebecca K Siegert
- Laboratory for Molecular Medicine, Partners Healthcare Personalized Medicine, Cambridge, Massachusetts
| | - Andrea M Oza
- Laboratory for Molecular Medicine, Partners Healthcare Personalized Medicine, Cambridge, Massachusetts
| | - Michael A Gonzalez
- Division of Genomic Diagnostics, The Children's Hospital of Philadelphia, The University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania
| | - Sami S Amr
- Laboratory for Molecular Medicine, Partners Healthcare Personalized Medicine, Cambridge, Massachusetts; Center for Genomic Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
| | - Heidi L Rehm
- Laboratory for Molecular Medicine, Partners Healthcare Personalized Medicine, Cambridge, Massachusetts; Department of Pathology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts; Department of Medical and Population Genetics, The Broad Institute of the Massachusetts Institute of Technology and Harvard, Cambridge, Massachusetts
| | - Ahmad N Abou Tayoun
- Division of Genomic Diagnostics, The Children's Hospital of Philadelphia, The University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania; Genetics Department, Al Jalila Children's Specialty Hospital, Dubai, United Arab Emirates.
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33
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Xia H, Huang X, Xu H, Guo Y, Hu P, Deng X, Yang Z, Liu A, Deng H. An OTOF Frameshift Variant Associated with Auditory Neuropathy Spectrum Disorder. Curr Genomics 2018; 19:370-374. [PMID: 30065612 PMCID: PMC6030853 DOI: 10.2174/1389202919666171113152951] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2015] [Revised: 06/13/2016] [Accepted: 06/18/2016] [Indexed: 11/28/2022] Open
Abstract
Background: Auditory Neuropathy Spectrum Disorder (ANSD) is manifested as impairment of auditory nerve activity but preservation of the outer hair cell function. Objective: This study was to detect the disease-causing gene and variant(s) in a Chinese ANSD family. Methods: A four-generation consanguineous Chinese ANSD family and 200 unrelated healthy controls were enrolled. Exome sequencing and Sanger sequencing were applied to identify the genetic basis for ANSD in this family. Results: Exome sequencing detected a c.1236delC variant of the otoferlin gene in an apparently homozygous state. Sanger sequencing confirmed that the variant co-segregating with the phenotype of hearing impairments in this family. The variant was not detected in 200 healthy controls. The c.1236delC alteration may result in a truncated otoferlin missing the C2C-C2F domains and the C-terminal transmembrane domain, and thus severely damages Ca2+-dependent synaptic vesicle fusion and targeting function of the otoferlin. Conclusion: Our study suggested that the c.1236delC alteration in the otoferlin gene may be the disease-causing variant in this family, and also shed new light on genetic counseling to this ANSD family.
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Affiliation(s)
- Hong Xia
- Center for Experimental Medicine and Department of Neurology, The Third Xiangya Hospital, Central South University, Changsha, China.,Department of Emergency, The Third Xiangya Hospital, Central South University, Changsha, China
| | - Xiangjun Huang
- Department of General Surgery, The First Hospital of Hunan University of Chinese Medicine, Changsha, China
| | - Hongbo Xu
- Center for Experimental Medicine and Department of Neurology, The Third Xiangya Hospital, Central South University, Changsha, China
| | - Yi Guo
- Center for Experimental Medicine and Department of Neurology, The Third Xiangya Hospital, Central South University, Changsha, China.,Department of Medical Information, Information Security and Big Data Research Institute, Central South University, Changsha, China
| | - Pengzhi Hu
- Center for Experimental Medicine and Department of Neurology, The Third Xiangya Hospital, Central South University, Changsha, China.,Department of Radiology, The Third Xiangya Hospital, Central South University, Changsha, China
| | - Xiong Deng
- Center for Experimental Medicine and Department of Neurology, The Third Xiangya Hospital, Central South University, Changsha, China
| | - Zhijian Yang
- Center for Experimental Medicine and Department of Neurology, The Third Xiangya Hospital, Central South University, Changsha, China
| | - An Liu
- Department of Otolaryngology-Head Neck Surgery, The Third Xiangya Hospital, Central South University, Changsha, China
| | - Hao Deng
- Center for Experimental Medicine and Department of Neurology, The Third Xiangya Hospital, Central South University, Changsha, China
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Finelli MJ, Oliver PL. TLDc proteins: new players in the oxidative stress response and neurological disease. Mamm Genome 2017; 28:395-406. [PMID: 28707022 PMCID: PMC5614904 DOI: 10.1007/s00335-017-9706-7] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Accepted: 07/03/2017] [Indexed: 12/14/2022]
Abstract
Oxidative stress (OS) arises from an imbalance in the cellular redox state, which can lead to intracellular damage and ultimately cell death. OS occurs as a result of normal ageing, but it is also implicated as a common etiological factor in neurological disease; thus identifying novel proteins that modulate the OS response may facilitate the design of new therapeutic approaches applicable to many disorders. In this review, we describe the recent progress that has been made using a range of genetic approaches to understand a family of proteins that share the highly conserved TLDc domain. We highlight their shared ability to prevent OS-related cell death and their unique functional characteristics, as well as discussing their potential application as new neuroprotective factors. Furthermore, with an increasing number of pathogenic mutations leading to epilepsy and hearing loss being discovered in the TLDc protein TBC1D24, understanding the function of this family has important implications for a range of inherited neurological diseases.
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Affiliation(s)
- Mattéa J Finelli
- Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, Oxford, OX1 3PT, UK
| | - Peter L Oliver
- Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, Oxford, OX1 3PT, UK.
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35
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Rehman AU, Friedman TB, Griffith AJ. Unresolved questions regarding human hereditary deafness. Oral Dis 2017; 23:551-558. [PMID: 27259978 PMCID: PMC5136515 DOI: 10.1111/odi.12516] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2016] [Revised: 05/27/2016] [Accepted: 05/30/2016] [Indexed: 01/18/2023]
Abstract
Human hearing loss is a common neurosensory disorder about which many basic research and clinically relevant questions are unresolved. This review on hereditary deafness focuses on three examples considered at first glance to be uncomplicated, however, upon inspection, are enigmatic and ripe for future research efforts. The three examples of clinical and genetic complexities are drawn from studies of (i) Pendred syndrome/DFNB4 (PDS, OMIM 274600), (ii) Perrault syndrome (deafness and infertility) due to mutations of CLPP (PRTLS3, OMIM 614129), and (iii) the unexplained extensive clinical variability associated with TBC1D24 mutations. At present, it is unknown how different mutations of TBC1D24 cause non-syndromic deafness (DFNB86, OMIM 614617), epilepsy (OMIM 605021), epilepsy with deafness, or DOORS syndrome (OMIM 220500) that is characterized by deafness, onychodystrophy (alteration of toenail or fingernail morphology), osteodystrophy (defective development of bone), mental retardation, and seizures. A comprehensive understanding of the multifaceted roles of each gene associated with human deafness is expected to provide future opportunities for restoration as well as preservation of normal hearing.
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Affiliation(s)
- A U Rehman
- Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD, USA
| | - T B Friedman
- Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD, USA
| | - A J Griffith
- Otolaryngology Branch, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD, USA
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36
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Banuelos E, Ramsey K, Belnap N, Krishnan M, Balak C, Szelinger S, Siniard AL, Russell M, Richholt R, De Both M, Piras I, Naymik M, Claasen AM, Rangasamy S, Huentelman MJ, Craig DW, Campeau PM, Narayanan V, Schrauwen I. Case Report: Novel mutations in TBC1D24 are associated with autosomal dominant tonic-clonic and myoclonic epilepsy and recessive Parkinsonism, psychosis, and intellectual disability. F1000Res 2017; 6:553. [PMID: 28663785 PMCID: PMC5473401 DOI: 10.12688/f1000research.10588.1] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 02/22/2017] [Indexed: 12/27/2022] Open
Abstract
Mutations disrupting presynaptic protein TBC1D24 are associated with a variable neurological phenotype, including DOORS syndrome, myoclonic epilepsy, early-infantile epileptic encephalopathy, and non-syndromic hearing loss. In this report, we describe a family segregating autosomal dominant epilepsy, and a 37-year-old Caucasian female with a severe neurological phenotype including epilepsy, Parkinsonism, psychosis, visual and auditory hallucinations, gait ataxia and intellectual disability. Whole exome sequencing revealed two missense mutations in the TBC1D24 gene segregating within this family (c.1078C>T; p.Arg360Cys and c.404C>T; p.Pro135Leu). The female proband who presents with a severe neurological phenotype carries both of these mutations in a compound heterozygous state. The p.Pro135Leu variant, however, is present in the proband's mother and sibling as well, and is consistent with an autosomal dominant pattern linked to tonic-clonic and myoclonic epilepsy. In conclusion, we describe a single family in which TBC1D24 mutations cause expanded dominant and recessive phenotypes. In addition, we discuss and highlight that some variants in TBC1D24 might cause a dominant susceptibility to epilepsy.
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Affiliation(s)
- Erika Banuelos
- Center for Rare Childhood Disorders, Translational Genomics Research Institute, Phoenix, AZ, 85004, USA.,Neurogenomics Division, Translational Genomics Research Institute, Phoenix, AZ, 85004, USA
| | - Keri Ramsey
- Center for Rare Childhood Disorders, Translational Genomics Research Institute, Phoenix, AZ, 85004, USA.,Neurogenomics Division, Translational Genomics Research Institute, Phoenix, AZ, 85004, USA
| | - Newell Belnap
- Center for Rare Childhood Disorders, Translational Genomics Research Institute, Phoenix, AZ, 85004, USA.,Neurogenomics Division, Translational Genomics Research Institute, Phoenix, AZ, 85004, USA
| | - Malavika Krishnan
- Center for Rare Childhood Disorders, Translational Genomics Research Institute, Phoenix, AZ, 85004, USA.,Neurogenomics Division, Translational Genomics Research Institute, Phoenix, AZ, 85004, USA
| | - Chris Balak
- Center for Rare Childhood Disorders, Translational Genomics Research Institute, Phoenix, AZ, 85004, USA.,Neurogenomics Division, Translational Genomics Research Institute, Phoenix, AZ, 85004, USA
| | - Szabolcs Szelinger
- Center for Rare Childhood Disorders, Translational Genomics Research Institute, Phoenix, AZ, 85004, USA.,Neurogenomics Division, Translational Genomics Research Institute, Phoenix, AZ, 85004, USA
| | - Ashley L Siniard
- Center for Rare Childhood Disorders, Translational Genomics Research Institute, Phoenix, AZ, 85004, USA.,Neurogenomics Division, Translational Genomics Research Institute, Phoenix, AZ, 85004, USA
| | - Megan Russell
- Center for Rare Childhood Disorders, Translational Genomics Research Institute, Phoenix, AZ, 85004, USA.,Neurogenomics Division, Translational Genomics Research Institute, Phoenix, AZ, 85004, USA
| | - Ryan Richholt
- Center for Rare Childhood Disorders, Translational Genomics Research Institute, Phoenix, AZ, 85004, USA.,Neurogenomics Division, Translational Genomics Research Institute, Phoenix, AZ, 85004, USA
| | - Matt De Both
- Center for Rare Childhood Disorders, Translational Genomics Research Institute, Phoenix, AZ, 85004, USA.,Neurogenomics Division, Translational Genomics Research Institute, Phoenix, AZ, 85004, USA
| | - Ignazio Piras
- Center for Rare Childhood Disorders, Translational Genomics Research Institute, Phoenix, AZ, 85004, USA.,Neurogenomics Division, Translational Genomics Research Institute, Phoenix, AZ, 85004, USA
| | - Marcus Naymik
- Center for Rare Childhood Disorders, Translational Genomics Research Institute, Phoenix, AZ, 85004, USA.,Neurogenomics Division, Translational Genomics Research Institute, Phoenix, AZ, 85004, USA
| | - Ana M Claasen
- Center for Rare Childhood Disorders, Translational Genomics Research Institute, Phoenix, AZ, 85004, USA.,Neurogenomics Division, Translational Genomics Research Institute, Phoenix, AZ, 85004, USA
| | - Sampathkumar Rangasamy
- Center for Rare Childhood Disorders, Translational Genomics Research Institute, Phoenix, AZ, 85004, USA.,Neurogenomics Division, Translational Genomics Research Institute, Phoenix, AZ, 85004, USA
| | - Matthew J Huentelman
- Center for Rare Childhood Disorders, Translational Genomics Research Institute, Phoenix, AZ, 85004, USA.,Neurogenomics Division, Translational Genomics Research Institute, Phoenix, AZ, 85004, USA
| | - David W Craig
- Center for Rare Childhood Disorders, Translational Genomics Research Institute, Phoenix, AZ, 85004, USA.,Neurogenomics Division, Translational Genomics Research Institute, Phoenix, AZ, 85004, USA
| | - Philippe M Campeau
- Department of Pediatrics, CHU Sainte-Justine Research Center and University of Montreal, Montreal, QC, H3T 1C5, Canada
| | - Vinodh Narayanan
- Center for Rare Childhood Disorders, Translational Genomics Research Institute, Phoenix, AZ, 85004, USA.,Neurogenomics Division, Translational Genomics Research Institute, Phoenix, AZ, 85004, USA
| | - Isabelle Schrauwen
- Center for Rare Childhood Disorders, Translational Genomics Research Institute, Phoenix, AZ, 85004, USA.,Neurogenomics Division, Translational Genomics Research Institute, Phoenix, AZ, 85004, USA
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37
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Ngoh A, Bras J, Guerreiro R, McTague A, Ng J, Meyer E, Chong WK, Boyd S, MacLellan L, Kirkpatrick M, Kurian MA. TBC1D24 Mutations in a Sibship with Multifocal Polymyoclonus. TREMOR AND OTHER HYPERKINETIC MOVEMENTS (NEW YORK, N.Y.) 2017; 7:452. [PMID: 28428906 PMCID: PMC5395678 DOI: 10.7916/d8q52vbv] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/25/2017] [Accepted: 03/16/2017] [Indexed: 01/02/2023]
Abstract
Background Advances in molecular genetic technologies have improved our understanding of genetic causes of rare neurological disorders with features of myoclonus. Case Report A family with two affected siblings, presenting with multifocal polymyoclonus and neurodevelopmental delay, was recruited for whole-exome sequencing following unyielding diagnostic neurometabolic investigations. Compound heterozygous mutations in TBC1D24, a gene previously associated with various epilepsy phenotypes and hearing loss, were identified in both siblings. The mutations included a missense change c.457G>A (p.Glu157Lys), and a novel frameshift mutation c.545del (p.Thr182Serfs*6). Discussion We propose that TBC1D24-related diseases should be in the differential diagnosis for children with polymyoclonus.
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Affiliation(s)
- Adeline Ngoh
- Neurosciences Unit, University College London, Institute of Child Health, London, UK.,Department of Neurology, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
| | - Jose Bras
- Department of Molecular Neuroscience, UCL Institute of Neurology, London, UK.,Department of Medical Sciences and Institute of Biomedicine - iBiMED, University of Aveiro, Aveiro, Portugal
| | - Rita Guerreiro
- Department of Molecular Neuroscience, UCL Institute of Neurology, London, UK.,Department of Medical Sciences and Institute of Biomedicine - iBiMED, University of Aveiro, Aveiro, Portugal
| | - Amy McTague
- Neurosciences Unit, University College London, Institute of Child Health, London, UK.,Department of Neurology, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
| | - Joanne Ng
- Neurosciences Unit, University College London, Institute of Child Health, London, UK.,Department of Neurology, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
| | - Esther Meyer
- Neurosciences Unit, University College London, Institute of Child Health, London, UK
| | - W Kling Chong
- Department of Neuroradiology, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
| | - Stewart Boyd
- Department of Neurophysiology, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
| | | | | | - Manju A Kurian
- Neurosciences Unit, University College London, Institute of Child Health, London, UK.,Department of Neurology, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
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38
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Uezu A, Kanak DJ, Bradshaw TWA, Soderblom EJ, Catavero CM, Burette AC, Weinberg RJ, Soderling SH. Identification of an elaborate complex mediating postsynaptic inhibition. Science 2017; 353:1123-9. [PMID: 27609886 DOI: 10.1126/science.aag0821] [Citation(s) in RCA: 214] [Impact Index Per Article: 30.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2016] [Accepted: 07/25/2016] [Indexed: 12/13/2022]
Abstract
Inhibitory synapses dampen neuronal activity through postsynaptic hyperpolarization. The composition of the inhibitory postsynapse and the mechanistic basis of its regulation, however, remain poorly understood. We used an in vivo chemico-genetic proximity-labeling approach to discover inhibitory postsynaptic proteins. Quantitative mass spectrometry not only recapitulated known inhibitory postsynaptic proteins but also revealed a large network of new proteins, many of which are either implicated in neurodevelopmental disorders or are of unknown function. Clustered regularly interspaced short palindromic repeats (CRISPR) depletion of one of these previously uncharacterized proteins, InSyn1, led to decreased postsynaptic inhibitory sites, reduced the frequency of miniature inhibitory currents, and increased excitability in the hippocampus. Our findings uncover a rich and functionally diverse assemblage of previously unknown proteins that regulate postsynaptic inhibition and might contribute to developmental brain disorders.
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Affiliation(s)
- Akiyoshi Uezu
- The Department of Cell Biology, Duke University Medical School, Durham, NC 27703, USA
| | - Daniel J Kanak
- The Department of Cell Biology, Duke University Medical School, Durham, NC 27703, USA
| | - Tyler W A Bradshaw
- The Department of Cell Biology, Duke University Medical School, Durham, NC 27703, USA
| | - Erik J Soderblom
- The Department of Cell Biology, Duke University Medical School, Durham, NC 27703, USA. Duke Proteomics and Metabolomics Shared Resource and Duke Center for Genomic and Computational Biology, Duke University Medical School, Durham, NC 27703, USA
| | - Christina M Catavero
- The Department of Cell Biology, Duke University Medical School, Durham, NC 27703, USA
| | - Alain C Burette
- Department of Cell Biology and Physiology, University of North Carolina, Chapel Hill, NC 27599, USA. Neuroscience Center, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Richard J Weinberg
- Department of Cell Biology and Physiology, University of North Carolina, Chapel Hill, NC 27599, USA. Neuroscience Center, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Scott H Soderling
- The Department of Cell Biology, Duke University Medical School, Durham, NC 27703, USA. The Department of Neurobiology, Duke University Medical School, Durham, NC 27703, USA.
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Fischer B, Lüthy K, Paesmans J, De Koninck C, Maes I, Swerts J, Kuenen S, Uytterhoeven V, Verstreken P, Versées W. Skywalker-TBC1D24 has a lipid-binding pocket mutated in epilepsy and required for synaptic function. Nat Struct Mol Biol 2016; 23:965-973. [DOI: 10.1038/nsmb.3297] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Accepted: 08/25/2016] [Indexed: 01/08/2023]
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40
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Pediatric otolaryngology, molecular diagnosis of hereditary hearing loss: next-generation sequencing approach. Curr Opin Otolaryngol Head Neck Surg 2016; 23:480-4. [PMID: 26488533 DOI: 10.1097/moo.0000000000000208] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE OF REVIEW Sensorineural hearing loss (SNHL) is the most common sensory birth defect. The purpose of this article is to review the advances in next-generation sequencing (NGS) and molecular diagnosis of hereditary hearing loss. RECENT FINDINGS Early diagnosis and detection of SNHL is critical for the development of appropriate speech and language, as neuroplasticity peaks in the first few years of life. There has been increased accuracy of NGS genetic testing, which has helped created a paradigm shift in the diagnosis of hearing loss. The diagnostic yield of genetic testing now approaches that of radiographic imaging; however, there remains a difference in cost and time delay. With the introduction of comprehensive genetic panels, 23-129 genes can be sequenced from the same blood sample. SUMMARY Diagnostic genetic testing of SNHL in the past has been confined to a few genes through Sanger sequencing. The advent of NGS allows for development of comprehensive genetic panels, which test for up to 129 genes while improving the accuracy and efficiency of testing. This type of testing may become more common as the costs decrease and more genes are discovered.
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41
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Mishra AK, Lambright DG. Invited review: Small GTPases and their GAPs. Biopolymers 2016; 105:431-48. [PMID: 26972107 PMCID: PMC5439442 DOI: 10.1002/bip.22833] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2016] [Revised: 02/16/2016] [Accepted: 03/10/2016] [Indexed: 12/11/2022]
Abstract
Widespread utilization of small GTPases as major regulatory hubs in many different biological systems derives from a conserved conformational switch mechanism that facilitates cycling between GTP-bound active and GDP-bound inactive states under control of guanine nucleotide exchange factors (GEFs) and GTPase activating proteins (GAPs), which accelerate slow intrinsic rates of activation by nucleotide exchange and deactivation by GTP hydrolysis, respectively. Here we review developments leading to current understanding of intrinsic and GAP catalyzed GTP hydrolytic reactions in small GTPases from structural, molecular and chemical mechanistic perspectives. Despite the apparent simplicity of the GTPase cycle, the structural bases underlying the hallmark hydrolytic reaction and catalytic acceleration by GAPs are considerably more diverse than originally anticipated. Even the most fundamental aspects of the reaction mechanism have been challenging to decipher. Through a combination of experimental and in silico approaches, the outlines of a consensus view have begun to emerge for the best studied paradigms. Nevertheless, recent observations indicate that there is still much to be learned. © 2016 Wiley Periodicals, Inc. Biopolymers 105: 431-448, 2016.
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Affiliation(s)
- Ashwini K Mishra
- Program in Molecular Medicine and Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA, 01605
| | - David G Lambright
- Program in Molecular Medicine and Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA, 01605
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42
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Balestrini S, Milh M, Castiglioni C, Lüthy K, Finelli MJ, Verstreken P, Cardon A, Stražišar BG, Holder JL, Lesca G, Mancardi MM, Poulat AL, Repetto GM, Banka S, Bilo L, Birkeland LE, Bosch F, Brockmann K, Cross JH, Doummar D, Félix TM, Giuliano F, Hori M, Hüning I, Kayserili H, Kini U, Lees MM, Meenakshi G, Mewasingh L, Pagnamenta AT, Peluso S, Mey A, Rice GM, Rosenfeld JA, Taylor JC, Troester MM, Stanley CM, Ville D, Walkiewicz M, Falace A, Fassio A, Lemke JR, Biskup S, Tardif J, Ajeawung NF, Tolun A, Corbett M, Gecz J, Afawi Z, Howell KB, Oliver KL, Berkovic SF, Scheffer IE, de Falco FA, Oliver PL, Striano P, Zara F, Campeau PM, Sisodiya SM. TBC1D24 genotype-phenotype correlation: Epilepsies and other neurologic features. Neurology 2016; 87:77-85. [PMID: 27281533 PMCID: PMC4932231 DOI: 10.1212/wnl.0000000000002807] [Citation(s) in RCA: 79] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2015] [Accepted: 03/28/2016] [Indexed: 11/15/2022] Open
Abstract
Objective: To evaluate the phenotypic spectrum associated with mutations in TBC1D24. Methods: We acquired new clinical, EEG, and neuroimaging data of 11 previously unreported and 37 published patients. TBC1D24 mutations, identified through various sequencing methods, can be found online (http://lovd.nl/TBC1D24). Results: Forty-eight patients were included (28 men, 20 women, average age 21 years) from 30 independent families. Eighteen patients (38%) had myoclonic epilepsies. The other patients carried diagnoses of focal (25%), multifocal (2%), generalized (4%), and unclassified epilepsy (6%), and early-onset epileptic encephalopathy (25%). Most patients had drug-resistant epilepsy. We detail EEG, neuroimaging, developmental, and cognitive features, treatment responsiveness, and physical examination. In silico evaluation revealed 7 different highly conserved motifs, with the most common pathogenic mutation located in the first. Neuronal outgrowth assays showed that some TBC1D24 mutations, associated with the most severe TBC1D24-associated disorders, are not necessarily the most disruptive to this gene function. Conclusions: TBC1D24-related epilepsy syndromes show marked phenotypic pleiotropy, with multisystem involvement and severity spectrum ranging from isolated deafness (not studied here), benign myoclonic epilepsy restricted to childhood with complete seizure control and normal intellect, to early-onset epileptic encephalopathy with severe developmental delay and early death. There is no distinct correlation with mutation type or location yet, but patterns are emerging. Given the phenotypic breadth observed, TBC1D24 mutation screening is indicated in a wide variety of epilepsies. A TBC1D24 consortium was formed to develop further research on this gene and its associated phenotypes.
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43
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Finelli MJ, Sanchez-Pulido L, Liu KX, Davies KE, Oliver PL. The Evolutionarily Conserved Tre2/Bub2/Cdc16 (TBC), Lysin Motif (LysM), Domain Catalytic (TLDc) Domain Is Neuroprotective against Oxidative Stress. J Biol Chem 2016; 291:2751-63. [PMID: 26668325 PMCID: PMC4742741 DOI: 10.1074/jbc.m115.685222] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2015] [Revised: 12/01/2015] [Indexed: 11/16/2022] Open
Abstract
Oxidative stress is a pathological feature of many neurological disorders; therefore, utilizing proteins that are protective against such cellular insults is a potentially valuable therapeutic approach. Oxidation resistance 1 (OXR1) has been shown previously to be critical for oxidative stress resistance in neuronal cells; deletion of this gene causes neurodegeneration in mice, yet conversely, overexpression of OXR1 is protective in cellular and mouse models of amyotrophic lateral sclerosis. However, the molecular mechanisms involved are unclear. OXR1 contains the Tre2/Bub2/Cdc16 (TBC), lysin motif (LysM), domain catalytic (TLDc) domain, a motif present in a family of proteins including TBC1 domain family member 24 (TBC1D24), a protein mutated in a range of disorders characterized by seizures, hearing loss, and neurodegeneration. The TLDc domain is highly conserved across species, although the structure-function relationship is unknown. To understand the role of this domain in the stress response, we carried out systematic analysis of all mammalian TLDc domain-containing proteins, investigating their expression and neuroprotective properties in parallel. In addition, we performed a detailed structural and functional study of this domain in which we identified key residues required for its activity. Finally, we present a new mouse insertional mutant of Oxr1, confirming that specific disruption of the TLDc domain in vivo is sufficient to cause neurodegeneration. Our data demonstrate that the integrity of the TLDc domain is essential for conferring neuroprotection, an important step in understanding the functional significance of all TLDc domain-containing proteins in the cellular stress response and disease.
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Affiliation(s)
- Mattéa J Finelli
- From the MRC Functional Genomics Unit, Department of Physiology, Anatomy, and Genetics, University of Oxford, Parks Road, Oxford OX1 3PT, United Kingdom
| | - Luis Sanchez-Pulido
- From the MRC Functional Genomics Unit, Department of Physiology, Anatomy, and Genetics, University of Oxford, Parks Road, Oxford OX1 3PT, United Kingdom
| | - Kevin X Liu
- From the MRC Functional Genomics Unit, Department of Physiology, Anatomy, and Genetics, University of Oxford, Parks Road, Oxford OX1 3PT, United Kingdom
| | - Kay E Davies
- From the MRC Functional Genomics Unit, Department of Physiology, Anatomy, and Genetics, University of Oxford, Parks Road, Oxford OX1 3PT, United Kingdom
| | - Peter L Oliver
- From the MRC Functional Genomics Unit, Department of Physiology, Anatomy, and Genetics, University of Oxford, Parks Road, Oxford OX1 3PT, United Kingdom
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44
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A Novel C-Terminal CIB2 (Calcium and Integrin Binding Protein 2) Mutation Associated with Non-Syndromic Hearing Loss in a Hispanic Family. PLoS One 2015; 10:e0133082. [PMID: 26426422 PMCID: PMC4591343 DOI: 10.1371/journal.pone.0133082] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2015] [Accepted: 06/22/2015] [Indexed: 01/29/2023] Open
Abstract
Hearing loss is a complex disorder caused by both genetic and environmental factors. Previously, mutations in CIB2 have been identified as a common cause of genetic hearing loss in Pakistani and Turkish populations. Here we report a novel (c.556C>T; p.(Arg186Trp)) transition mutation in the CIB2 gene identified through whole exome sequencing (WES) in a Caribbean Hispanic family with non-syndromic hearing loss. CIB2 belongs to the family of calcium-and integrin-binding (CIB) proteins. The carboxy-termini of CIB proteins are associated with calcium binding and intracellular signaling. The p.(Arg186Trp) mutation is localized within predicted type II PDZ binding ligand at the carboxy terminus. Our ex vivo studies revealed that the mutation did not alter the interactions of CIB2 with Whirlin, nor its targeting to the tips of hair cell stereocilia. However, we found that the mutation disrupts inhibition of ATP-induced Ca2+ responses by CIB2 in a heterologous expression system. Our findings support p.(Arg186Trp) mutation as a cause for hearing loss in this Hispanic family. In addition, it further highlights the necessity of the calcium binding property of CIB2 for normal hearing.
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Bakhchane A, Charif M, Salime S, Boulouiz R, Nahili H, Roky R, Lenaers G, Barakat A. Recessive TBC1D24 Mutations Are Frequent in Moroccan Non-Syndromic Hearing Loss Pedigrees. PLoS One 2015; 10:e0138072. [PMID: 26371875 PMCID: PMC4570774 DOI: 10.1371/journal.pone.0138072] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2015] [Accepted: 08/26/2015] [Indexed: 11/18/2022] Open
Abstract
Mutations in the TBC1D24 gene are responsible for four neurological presentations: infantile epileptic encephalopathy, infantile myoclonic epilepsy, DOORS (deafness, onychodystrophy, osteodystrophy, mental retardation and seizures) and NSHL (non-syndromic hearing loss). For the latter, two recessive (DFNB86) and one dominant (DFNA65) mutations have so far been identified in consanguineous Pakistani and European/Chinese families, respectively. Here we report the results of a genetic study performed on a large Moroccan cohort of deaf patients that identified three families with compound heterozygote mutations in TBC1D24. Four novel mutations were identified, among which, one c.641G>A (p.Arg214His) was present in the three families, and has a frequency of 2% in control Moroccan population with normal hearing, suggesting that it acts as an hypomorphic variant leading to restricted deafness when combined with another recessive severe mutation. Altogether, our results show that mutations in TBC1D24 gene are a frequent cause (>2%) of NSHL in Morocco, and that due to its possible compound heterozygote recessive transmission, this gene should be further considered and screened in other deaf cohorts.
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Affiliation(s)
- Amina Bakhchane
- Laboratoire de Génétique Moléculaire Humaine, Département de Recherche Scientifique, Institut Pasteur du Maroc, Casablanca, Morocco
| | - Majida Charif
- Laboratoire de Génétique Moléculaire Humaine, Département de Recherche Scientifique, Institut Pasteur du Maroc, Casablanca, Morocco
- Institut des Neurosciences de Montpellier, U1051 de l’INSERM, Université de Montpellier, BP 74103, 34091 Montpellier cedex 05, France
- PREMMi, Mitochondrial Medicine Research Centre, Université d'Angers, CHU Bât IRIS/IBS, Rue des Capucins, 49933 Angers cedex 9, France
| | - Sara Salime
- Laboratoire de Génétique Moléculaire Humaine, Département de Recherche Scientifique, Institut Pasteur du Maroc, Casablanca, Morocco
- Institut des Neurosciences de Montpellier, U1051 de l’INSERM, Université de Montpellier, BP 74103, 34091 Montpellier cedex 05, France
| | - Redouane Boulouiz
- Laboratoire de Génétique Moléculaire Humaine, Département de Recherche Scientifique, Institut Pasteur du Maroc, Casablanca, Morocco
| | - Halima Nahili
- Laboratoire de Génétique Moléculaire Humaine, Département de Recherche Scientifique, Institut Pasteur du Maroc, Casablanca, Morocco
| | - Rachida Roky
- Université Hassan II Ain Chock, Laboratoire de Physiologie et génétique moléculaire, Km 8 Route d'El Jadida, B.P 5366 Maarif, Casablanca, 20100, Morocco
| | - Guy Lenaers
- Institut des Neurosciences de Montpellier, U1051 de l’INSERM, Université de Montpellier, BP 74103, 34091 Montpellier cedex 05, France
- PREMMi, Mitochondrial Medicine Research Centre, Université d'Angers, CHU Bât IRIS/IBS, Rue des Capucins, 49933 Angers cedex 9, France
| | - Abdelhamid Barakat
- Laboratoire de Génétique Moléculaire Humaine, Département de Recherche Scientifique, Institut Pasteur du Maroc, Casablanca, Morocco
- * E-mail:
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Edvardson S, Gerhard F, Jalas C, Lachmann J, Golan D, Saada A, Shaag A, Ungermann C, Elpeleg O. Hypomyelination and developmental delay associated with VPS11 mutation in Ashkenazi-Jewish patients. J Med Genet 2015; 52:749-53. [PMID: 26307567 DOI: 10.1136/jmedgenet-2015-103239] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2015] [Accepted: 08/03/2015] [Indexed: 12/16/2022]
Abstract
BACKGROUND The genetic heterogeneity of developmental delay and cognitive impairment is vast. The endocytic network is essential for neural development and synaptic plasticity by regulating the sorting of numerous transmembrane proteins. Disruption of the pathway can lead to neuronal pathology. Endosomal biogenesis relies on two Rab proteins, Rab5 and Rab7, which bind to two hexameric tethering complexes, the endosomal class C core vacuole/endosome tethering complex (CORVET) and the late endosomal/lysosomal homotypic fusion and protein sorting complex (HOPS). Both complexes consist of four core proteins and differ by their specific Rab-binding proteins. OBJECTIVES To identify the molecular basis of a neurological disease, which consists of global developmental stagnation at 3-8 months, increasing appendicular spasticity, truncal hypotonia and acquired microcephaly, with variable seizure disorder, accompanied by thin corpus callosum, paucity of white matter and delayed myelination in eight patients from four unrelated Ashkenazi-Jewish (AJ) families. METHODS Exome analysis, homozygosity mapping and Mup1-GFP transport assay in mutant yeast. RESULTS Homozygosity for a missense mutation, p.Cys846Gly, in one of the endosomal biogenesis core proteins, VPS11, was identified in all the patients. This was shown to be a founder mutation with a carrier frequency of 0.6% in the AJ population. The homologous yeast mutant had moderate impairment of fusion of the late endosome to the vacuole in Mup1-GFP transport assay. CONCLUSIONS We speculate that in neuronal cells, impairment of fusion of the late endosome to the vacuole would attenuate the degradation of plasma membrane receptors, thereby underlying the progressive neuronal phenotype in our patients. The VPS11 p.Cys846Gly mutation should be added to the AJ carrier screening panel.
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Affiliation(s)
- Shimon Edvardson
- Monique and Jacques Roboh Department of Genetic Research, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
| | - Frank Gerhard
- Department of Biology/Chemistry, Biochemistry Section, University of Osnabrück, Osnabrück, Germany
| | - Chaim Jalas
- Bonei Olam, Center for Rare Jewish Genetic Disorders, Brooklyn, New York, USA
| | - Jens Lachmann
- Department of Biology/Chemistry, Biochemistry Section, University of Osnabrück, Osnabrück, Germany
| | - Dafna Golan
- Maccabi Health Services, Child Development Center, Jerusalem, Israel
| | - Ann Saada
- Monique and Jacques Roboh Department of Genetic Research, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
| | - Avraham Shaag
- Monique and Jacques Roboh Department of Genetic Research, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
| | - Christian Ungermann
- Department of Biology/Chemistry, Biochemistry Section, University of Osnabrück, Osnabrück, Germany
| | - Orly Elpeleg
- Monique and Jacques Roboh Department of Genetic Research, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
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Lu X, Sipe CW. Developmental regulation of planar cell polarity and hair-bundle morphogenesis in auditory hair cells: lessons from human and mouse genetics. WILEY INTERDISCIPLINARY REVIEWS-DEVELOPMENTAL BIOLOGY 2015; 5:85-101. [PMID: 26265594 DOI: 10.1002/wdev.202] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2015] [Revised: 06/12/2015] [Accepted: 06/29/2015] [Indexed: 12/11/2022]
Abstract
Hearing loss is the most common and costly sensory defect in humans and genetic causes underlie a significant proportion of affected individuals. In mammals, sound is detected by hair cells (HCs) housed in the cochlea of the inner ear, whose function depends on a highly specialized mechanotransduction organelle, the hair bundle. Understanding the factors that regulate the development and functional maturation of the hair bundle is crucial for understanding the pathophysiology of human deafness. Genetic analysis of deafness genes in animal models, together with complementary forward genetic screens and conditional knock-out mutations in essential genes, have provided great insights into the molecular machinery underpinning hair-bundle development and function. In this review, we highlight recent advances in our understanding of hair-bundle morphogenesis, with an emphasis on the molecular pathways governing hair-bundle polarity and orientation. We next discuss the proteins and structural elements important for hair-cell mechanotransduction as well as hair-bundle cohesion and maintenance. In addition, developmental signals thought to regulate tonotopic features of HCs are introduced. Finally, novel approaches that complement classic genetics for studying the molecular etiology of human deafness are presented. WIREs Dev Biol 2016, 5:85-101. doi: 10.1002/wdev.202 For further resources related to this article, please visit the WIREs website.
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Affiliation(s)
- Xiaowei Lu
- Department of Cell Biology, University of Virginia, Charlottesville, VA, USA
| | - Conor W Sipe
- Department of Biology, University of Virginia, Charlottesville, VA, USA
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Lesca G, Depienne C. Epilepsy genetics: the ongoing revolution. Rev Neurol (Paris) 2015; 171:539-57. [PMID: 26003806 DOI: 10.1016/j.neurol.2015.01.569] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Revised: 12/24/2014] [Accepted: 01/20/2015] [Indexed: 01/04/2023]
Abstract
Epilepsies have long remained refractory to gene identification due to several obstacles, including a highly variable inter- and intrafamilial expressivity of the phenotypes, a high frequency of phenocopies, and a huge genetic heterogeneity. Recent technological breakthroughs, such as array comparative genomic hybridization and next generation sequencing, have been leading, in the past few years, to the identification of an increasing number of genomic regions and genes in which mutations or copy-number variations cause various epileptic disorders, revealing an enormous diversity of pathophysiological mechanisms. The field that has undergone the most striking revolution is that of epileptic encephalopathies, for which most of causing genes have been discovered since the year 2012. Some examples are the continuous spike-and-waves during slow-wave sleep and Landau-Kleffner syndromes for which the recent discovery of the role of GRIN2A mutations has finally confirmed the genetic bases. These new technologies begin to be used for diagnostic applications, and the main challenge now resides in the interpretation of the huge mass of variants detected by these methods. The identification of causative mutations in epilepsies provides definitive confirmation of the clinical diagnosis, allows accurate genetic counselling, and sometimes permits the development of new appropriate and specific antiepileptic therapies. Future challenges include the identification of the genetic or environmental factors that modify the epileptic phenotypes caused by mutations in a given gene and the understanding of the role of somatic mutations in sporadic epilepsies.
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Affiliation(s)
- G Lesca
- Service de génétique, groupement hospitalier Est, hospices civils de Lyon, 59, boulevard Pinel, 69677 Bron, France; Université Claude-Bernard Lyon 1, 43, boulevard du 11-Novembre-1918, 69100 Villeurbanne, France; CRNL, CNRS UMR 5292, Inserm U1028, bâtiment IMBL, 11, avenue Jean-Capelle, 69621 Villeurbanne cedex, France.
| | - C Depienne
- Département de génétique et cytogénétique, hôpital Pitié-Salpêtrière, AP-HP, 47-83, boulevard de l'Hôpital, 75651 Paris cedex 13, France; Sorbonne universités, UPMC université Paris 06, 4, place Jussieu, 75005 Paris, France; ICM, CNRS UMR 7225, Inserm U1127, 47, boulevard de l'Hôpital, 75651 Paris cedex 13, France
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Vona B, Nanda I, Hofrichter MAH, Shehata-Dieler W, Haaf T. Non-syndromic hearing loss gene identification: A brief history and glimpse into the future. Mol Cell Probes 2015; 29:260-70. [PMID: 25845345 DOI: 10.1016/j.mcp.2015.03.008] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2015] [Revised: 03/19/2015] [Accepted: 03/23/2015] [Indexed: 11/27/2022]
Abstract
From the first identified non-syndromic hearing loss gene in 1995, to those discovered in present day, the field of human genetics has witnessed an unparalleled revolution that includes the completion of the Human Genome Project in 2003 to the $1000 genome in 2014. This review highlights the classical and cutting-edge strategies for non-syndromic hearing loss gene identification that have been used throughout the twenty year history with a special emphasis on how the innovative breakthroughs in next generation sequencing technology have forever changed candidate gene approaches. The simplified approach afforded by next generation sequencing technology provides a second chance for the many linked loci in large and well characterized families that have been identified by linkage analysis but have presently failed to identify a causative gene. It also discusses some complexities that may restrict eventual candidate gene discovery and calls for novel approaches to answer some of the questions that make this simple Mendelian disorder so intriguing.
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Affiliation(s)
- Barbara Vona
- Institute of Human Genetics, Julius Maximilians University, Würzburg, Germany.
| | - Indrajit Nanda
- Institute of Human Genetics, Julius Maximilians University, Würzburg, Germany
| | | | - Wafaa Shehata-Dieler
- Comprehensive Hearing Center, Department of Otorhinolaryngology, Plastic, Aesthetic and Reconstructive Surgery, University Hospital, Würzburg, Germany
| | - Thomas Haaf
- Institute of Human Genetics, Julius Maximilians University, Würzburg, Germany
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Abstract
Next-generation sequencing (NGS) technologies have played a central role in the genetic revolution. These technologies, especially whole-exome sequencing, have become the primary tool of geneticists to identify the causative DNA variants in Mendelian disorders, including hereditary deafness. Current research estimates that 1% of all human genes have a function in hearing. To date, mutations in over 80 genes have been reported to cause nonsyndromic hearing loss (NSHL). Strikingly, more than a quarter of all known genes related to NSHL were discovered in the past 5 years via NGS technologies. In this article, we review recent developments in the usage of NGS for hereditary deafness, with an emphasis on whole-exome sequencing.
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