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Namba K, Mutai H, Matsunaga T, Kaneko H. Structural basis for pathogenic variants of GJB2 and hearing levels of patients with hearing loss. BMC Res Notes 2024; 17:131. [PMID: 38730444 PMCID: PMC11083831 DOI: 10.1186/s13104-024-06793-w] [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: 08/15/2023] [Accepted: 04/30/2024] [Indexed: 05/12/2024] Open
Abstract
OBJECTIVES The crystal structure of the six protomers of gap junction protein beta 2 (GJB2) enables prediction of the effect(s) of an amino acid substitution, thereby facilitating investigation of molecular pathogenesis of missense variants of GJB2. This study mainly focused on R143W variant that causes hearing loss, and investigated the relationship between amino acid substitution and 3-D structural changes in GJB2. METHODS Patients with nonsyndromic hearing loss who appeared to have two GJB2 pathogenic variants, including the R143W variant, were investigated. Because the X-ray crystal structure of the six protomers of the GJB2 protein is known, R143W and structurally related variants of GJB2 were modeled using this crystal structure as a template. The wild-type crystal structure and the variant computer-aided model were observed and the differences in molecular interactions within the two were analyzed. RESULTS The predicted structure demonstrated that the hydrogen bond between R143 and N206 was important for the stability of the protomer structure. From this prediction, R143W related N206S and N206T variants showed loss of the hydrogen bond. CONCLUSION Investigation of the genotypes and clinical data in patients carrying the R143W variant on an allele indicated that severity of hearing loss depends largely on the levels of dysfunction of the pathogenic variant on the allele, whereas a patient with the homozygous R143W variant demonstrated profound hearing loss. We concluded that these hearing impairments may be due to destabilization of the protomer structure of GJB2 caused by the R143W variant.
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Affiliation(s)
- Kazunori Namba
- Division of Hearing and Balance Research, National Institute of Sensory Organs, NHO Tokyo Medical Center, 2-5-1 Higashigaoka, Meguro-ku, Tokyo, 152-8902, Japan
| | - Hideki Mutai
- Division of Hearing and Balance Research, National Institute of Sensory Organs, NHO Tokyo Medical Center, 2-5-1 Higashigaoka, Meguro-ku, Tokyo, 152-8902, Japan
| | - Tatsuo Matsunaga
- Division of Hearing and Balance Research, National Institute of Sensory Organs, NHO Tokyo Medical Center, 2-5-1 Higashigaoka, Meguro-ku, Tokyo, 152-8902, Japan
- Medical Genetics Center, NHO Tokyo Medical Center, 2-5-1 Higashigaoka, Meguro-ku, Tokyo, 152-8902, Japan
| | - Hiroki Kaneko
- Health and Nutrition (NIBIOHN), National Institutes of Biomedical Innovation, 7-6-8 Saito-Asagi, Ibaraki, Osaka, 567-0085, Japan.
- The Institute of Natural Sciences, College of Humanities and Sciences, Nihon University, 3-25-40 Sakurajousui, Setagaya-ku, Tokyo, 156-8550, Japan.
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Quaio CRDAC, Coelho AVC, Moura LMS, Guedes RLM, Chen K, Ceroni JRM, Minillo RM, Caraciolo MP, Reis RDS, de Azevedo BMC, Nobrega MS, Teixeira ACB, Martinelli Lima M, da Mota TR, da Matta MC, Colichio GBC, Roncalho AL, Ferreira AFM, Campilongo GP, Perrone E, Virmond LDA, Moreno CA, Prota JRM, de França M, Cervato MC, de Almeida TF, de Oliveira Filho JB. Genomic study of nonsyndromic hearing loss in unaffected individuals: Frequency of pathogenic and likely pathogenic variants in a Brazilian cohort of 2,097 genomes. Front Genet 2022; 13:921324. [PMID: 36147510 PMCID: PMC9486813 DOI: 10.3389/fgene.2022.921324] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2022] [Accepted: 07/28/2022] [Indexed: 11/13/2022] Open
Abstract
Hearing loss (HL) is a common sensory deficit in humans and represents an important clinical and social burden. We studied whole-genome sequencing data of a cohort of 2,097 individuals from the Brazilian Rare Genomes Project who were unaffected by hearing loss to investigate pathogenic and likely pathogenic variants associated with nonsyndromic hearing loss (NSHL). We found relevant frequencies of individuals harboring these alterations: 222 heterozygotes (10.59%) for sequence variants, 54 heterozygotes (2.58%) for copy-number variants (CNV), and four homozygotes (0.19%) for sequence variants. The top five most frequent genes and their corresponding combined allelic frequencies (AF) were GJB2 (AF = 1.57%), STRC (AF = 1%), OTOA (AF = 0.69%), TMPRSS3 (AF = 0.41%), and OTOF (AF = 0.29%). The most frequent sequence variant was GJB2:c.35del (AF = 0.72%), followed by OTOA:p. (Glu787Ter) (AF = 0.61%), while the most recurrent CNV was a microdeletion of 57.9 kb involving the STRC gene (AF = 0.91%). An important fraction of these individuals (n = 104; 4.96%) presented variants associated with autosomal dominant forms of NSHL, which may imply the development of some hearing impairment in the future. Using data from the heterozygous individuals for recessive forms and the Hardy–Weinberg equation, we estimated the population frequency of affected individuals with autosomal recessive NSHL to be 1:2,222. Considering that the overall prevalence of HL in adults ranges from 4–15% worldwide, our data indicate that an important fraction of this condition may be associated with a monogenic origin and dominant inheritance.
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Affiliation(s)
- Caio Robledo D’ Angioli Costa Quaio
- Hospital Israelita Albert Einstein, São Paulo, SP, Brazil
- Instituto da Criança (Children’s Hospital), Hospital Das Clínicas HCFMUSP, Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil
- *Correspondence: Caio Robledo D’ Angioli Costa Quaio, ; Joao Bosco de Oliveira Filho,
| | | | - Livia Maria Silva Moura
- Hospital Israelita Albert Einstein, São Paulo, SP, Brazil
- VarsOmics, Sociedade Beneficente Israelita Brasileira Albert Einstein, São Paulo, SP, Brazil
| | - Rafael Lucas Muniz Guedes
- Hospital Israelita Albert Einstein, São Paulo, SP, Brazil
- VarsOmics, Sociedade Beneficente Israelita Brasileira Albert Einstein, São Paulo, SP, Brazil
| | - Kelin Chen
- Hospital Israelita Albert Einstein, São Paulo, SP, Brazil
| | | | | | - Marcel Pinheiro Caraciolo
- Hospital Israelita Albert Einstein, São Paulo, SP, Brazil
- VarsOmics, Sociedade Beneficente Israelita Brasileira Albert Einstein, São Paulo, SP, Brazil
| | - Rodrigo de Souza Reis
- Hospital Israelita Albert Einstein, São Paulo, SP, Brazil
- VarsOmics, Sociedade Beneficente Israelita Brasileira Albert Einstein, São Paulo, SP, Brazil
| | | | | | | | | | - Thamara Rayssa da Mota
- Hospital Israelita Albert Einstein, São Paulo, SP, Brazil
- Programa de Pós Graduação em Tecnologias Energéticas e Nucleares (PROTEN), UFPE, Recife, Brazil
| | | | | | | | | | | | - Eduardo Perrone
- Hospital Israelita Albert Einstein, São Paulo, SP, Brazil
- Departamento de Morfologia e Genética, Universidade Federal de São Paulo, São Paulo, SP, Brazil
| | | | - Carolina Araujo Moreno
- Hospital Israelita Albert Einstein, São Paulo, SP, Brazil
- Departamento de Medicina Translacional, Área de Genética Médica e Medicina Genômica, Faculdade de Ciências Médicas, Universidade Estadual de Campinas, Campinas, SP, Brazil
| | - Joana Rosa Marques Prota
- Hospital Israelita Albert Einstein, São Paulo, SP, Brazil
- Departamento de Medicina Translacional, Área de Genética Médica e Medicina Genômica, Faculdade de Ciências Médicas, Universidade Estadual de Campinas, Campinas, SP, Brazil
| | | | - Murilo Castro Cervato
- Hospital Israelita Albert Einstein, São Paulo, SP, Brazil
- VarsOmics, Sociedade Beneficente Israelita Brasileira Albert Einstein, São Paulo, SP, Brazil
| | | | - Joao Bosco de Oliveira Filho
- Hospital Israelita Albert Einstein, São Paulo, SP, Brazil
- *Correspondence: Caio Robledo D’ Angioli Costa Quaio, ; Joao Bosco de Oliveira Filho,
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Abstract
Hearing loss (HL) is an etiologically heterogeneous disorder that affects around 5% of the world's population. There has been an exponential increase in the identification of genes and variants responsible for hereditary HL over recent years. Iran, a country located in the Middle East, has a high prevalence of consanguineous marriages, so heterogeneous diseases such as HL are more common. Comprehensive studies using different strategies from linkage analysis to next-generation sequencing, especially exome-sequencing, have achieved significant success in identifying possible pathogens in deaf Iranian families. About 12% of non-syndromic autosomal recessive HL genes investigated to date, were first identified in families from Iran. Variations of 56 genes have been observed in families with NSHL in Iran. Variants in GJB2, SLC26A4, MYO15A, MYO7A, CDH23, and TMC1 account for 16.5%, 16.25%, 13.5%, 9.35%, 6.9% and 4.92%, cases of NSHL, respectively. In summary, there are also different diagnostic rates between studies conducted in Iran. In the comprehensive investigations conducted by the Genetic Research Center of the University of Social Welfare and Rehabilitation Sciences over the past 20 years, the overall diagnosis rate is about 80% while there are other studies with lower diagnostic rates which could reflect differences in project designs, sampling, and accuracy and validity of the methods used. Furthermore, there are several syndromic HHLs in Iran including, Waardenburg syndrome, BOR syndrome, Brown-Vialetto-Van Laere syndrome, Wolfram syndrome, among which Pendred and Usher syndromes are well-studied. These results are of importance for further investigation and elucidation of the molecular basis of HHL in Iran.
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The natural history of OTOF-related auditory neuropathy spectrum disorders: a multicenter study. Hum Genet 2021; 141:853-863. [PMID: 34424407 DOI: 10.1007/s00439-021-02340-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Accepted: 08/07/2021] [Indexed: 10/20/2022]
Abstract
Pathogenic variations in the OTOF gene are a common cause of hearing loss. To refine the natural history and genotype-phenotype correlations of OTOF-related auditory neuropathy spectrum disorders (ANSD), audiograms and distortion product otoacoustic emissions (DPOAEs) were collected from a diverse cohort of individuals diagnosed with OTOF-related ANSD by comprehensive genetic testing and also reported in the literature. Comparative analysis was undertaken to define genotype-phenotype relationships using a Monte Carlo algorithm. 67 audiograms and 25 DPOAEs from 49 unique individuals positive for OTOF-related ANSD were collected. 51 unique OTOF pathogenic variants were identified of which 21 were missense and 30 were loss of function (LoF; nonsense, splice-site, copy number variants, and indels). There was a statistically significant difference in low, middle, and high frequency hearing thresholds between missense/missense and LoF/missense genotypes as compared to LoF/LoF genotypes (average hearing threshold for low, middle and high frequencies 70.9, 76.0, and 73.4 dB vs 88.5, 95.6, and 94.7 dB) via Tukey's test with age as a co-variate (P = 0.0180, 0.0327, and 0.0347, respectively). Hearing declined during adolescence with missense/missense and LoF/missense genotypes, with an annual mid-frequency threshold deterioration of 0.87 dB/year and 1.87 dB/year, respectively. 8.5% of frequencies measured via DPOAE were lost per year in individuals with serial tests. Audioprofiling of OTOF-related ANSD suggests significantly worse hearing with LoF/LoF genotypes. The unique pattern of variably progressive OTOF-related autosomal recessive ANSD may be amenable to gene therapy in selected clinical scenarios.
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Lin YH, Wu PC, Tsai CY, Lin YH, Lo MY, Hsu SJ, Lin PH, Erdenechuluun J, Wu HP, Hsu CJ, Wu CC, Chen PL. Hearing Impairment with Monoallelic GJB2 Variants: A GJB2 Cause or Non-GJB2 Cause? J Mol Diagn 2021; 23:1279-1291. [PMID: 34325055 DOI: 10.1016/j.jmoldx.2021.07.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Revised: 03/23/2021] [Accepted: 07/07/2021] [Indexed: 12/26/2022] Open
Abstract
Recessive variants in GJB2 are the most common genetic cause of sensorineural hearing impairment. However, in many patients, only one variant in the GJB2 coding region is identified using conventional sequencing strategy (eg, Sanger sequencing), resulting in nonconfirmative diagnosis. Conceivably, there might be other unidentified pathogenic variants in the noncoding region of GJB2 or other deafness-causing genes in these patients. To address this, a next-generation sequencing-based diagnostic panel targeting the entire GJB2 gene and the coding regions of 158 other known deafness-causing genes was designed and applied to 95 patients with nonsyndromic sensorineural hearing impairment (including 81 Han Taiwanese and 14 Mongolian patients) in whom only a single GJB2 variant had been detected using conventional Sanger sequencing. The panel confirmed the genetic diagnosis in 24 patients (25.3%). Twenty-two of them had causative variants in several deafness-causing genes other than GJB2, including MYO15A, MYO7A, TECTA, POU4F3, KCNQ4, SLC26A4, OTOF, MT-RNR1, MITF, WFS1, and USH2A. The other two patients had causative variants in GJB2, including a Taiwanese patient with a mosaic maternal uniparental disomy c.235delC variant (approximately 69% mosaicism) and a Mongolian patient with compound heterozygous c.35dupG and c.35delG variants, which occurred at the same site. This study demonstrates the utility of next-generation sequencing in clarifying the genetic diagnosis of hearing-impaired patients with nonconfirmative GJB2 genotypes on conventional genetic examinations.
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Affiliation(s)
- Yi-Hsin Lin
- Department of Otolaryngology, National Taiwan University Hospital, National Taiwan University Hospital, Taipei, Taiwan; Institute of Molecular Medicine, National Taiwan University College of Medicine, Taipei, Taiwan
| | - Ping-Che Wu
- College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Cheng-Yu Tsai
- Department of Otolaryngology, National Taiwan University Hospital, National Taiwan University Hospital, Taipei, Taiwan; Graduate Institutes of Medical Genomic, National Taiwan University College of Medicine, Taipei, Taiwan
| | - Yin-Hung Lin
- Department of Otolaryngology, National Taiwan University Hospital, National Taiwan University Hospital, Taipei, Taiwan; Graduate Institutes of Medical Genomic, National Taiwan University College of Medicine, Taipei, Taiwan
| | - Ming-Yu Lo
- Department of Otolaryngology, National Taiwan University Hospital, National Taiwan University Hospital, Taipei, Taiwan; Institute of Molecular Medicine, National Taiwan University College of Medicine, Taipei, Taiwan
| | - Shu-Jui Hsu
- Graduate Institutes of Medical Genomic, National Taiwan University College of Medicine, Taipei, Taiwan
| | - Pei-Hsuan Lin
- Department of Otolaryngology, National Taiwan University Hospital Yunlin Branch, Yunlin, Taiwan
| | - Jargalkhuu Erdenechuluun
- Department of Otolaryngology, Mongolian National University of Medical Sciences, Ulaanbaatar, Mongolia; The EMJJ Otolaryngology Hospital, Ulaanbaatar, Mongolia
| | - Hung-Pin Wu
- Department of Otolaryngology Head and Neck Surgery, Taichung Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, Taichung, Taiwan; School of Medicine, Tzu Chi University, Hualien, Taiwan
| | - Chuan-Jen Hsu
- Department of Otolaryngology, National Taiwan University Hospital, National Taiwan University Hospital, Taipei, Taiwan; Department of Otolaryngology Head and Neck Surgery, Taichung Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, Taichung, Taiwan
| | - Chen-Chi Wu
- Department of Otolaryngology, National Taiwan University Hospital, National Taiwan University Hospital, Taipei, Taiwan; Clinical Medicine, National Taiwan University College of Medicine, Taipei, Taiwan.
| | - Pei-Lung Chen
- Institute of Molecular Medicine, National Taiwan University College of Medicine, Taipei, Taiwan; Graduate Institutes of Medical Genomic, National Taiwan University College of Medicine, Taipei, Taiwan; Clinical Medicine, National Taiwan University College of Medicine, Taipei, Taiwan; Department of Medical Genetics, National Taiwan University Hospital, National Taiwan University Hospital, Taipei, Taiwan; Department of Internal Medicine, National Taiwan University Hospital, National Taiwan University Hospital, Taipei, Taiwan.
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Mahfood M, Chouchen J, Kamal Eddine Ahmad Mohamed W, Al Mutery A, Harati R, Tlili A. Whole exome sequencing, in silico and functional studies confirm the association of the GJB2 mutation p.Cys169Tyr with deafness and suggest a role for the TMEM59 gene in the hearing process. Saudi J Biol Sci 2021; 28:4421-4429. [PMID: 34354426 PMCID: PMC8324942 DOI: 10.1016/j.sjbs.2021.04.036] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2020] [Revised: 04/11/2021] [Accepted: 04/12/2021] [Indexed: 12/25/2022] Open
Abstract
The development of next generation sequencing techniques has facilitated the detection of mutations at an unprecedented rate. These efficient tools have been particularly beneficial for extremely heterogeneous disorders such as autosomal recessive non-syndromic hearing loss, the most common form of genetic deafness. GJB2 mutations are the most common cause of hereditary hearing loss. Amongst them the NM_004004.5: c.506G > A (p.Cys169Tyr) mutation has been associated with varying severity of hearing loss with unclear segregation patterns. In this study, we report a large consanguineous Emirati family with severe to profound hearing loss fully segregating the GJB2 missense mutation p.Cys169Tyr. Whole exome sequencing (WES), in silico, splicing and expression analyses ruled out the implication of any other variants and confirmed the implication of the p.Cys169Tyr mutation in this deafness family. We also show preliminary murine expression analysis that suggests a link between the TMEM59 gene and the hearing process. The present study improves our understanding of the molecular pathogenesis of hearing loss. It also emphasizes the significance of combining next generation sequencing approaches and segregation analyses especially in the diagnosis of disorders characterized by complex genetic heterogeneity.
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Key Words
- ARNSHL, autosomal recessive non-syndromic hearing loss
- Actb, Actin beta
- BAM, Binary Alignment Map
- BWA, Burrows-Wheeler Aligner
- C1QTNF9, C1q and TNF related 9
- Cx26, Connexin 26
- ESRRAP2, Estrogen-Related Receptor Alpha Pseudogene 2
- GJB2 gene
- GJB2, Gap Junction Protein Beta 2
- HHLA1, HERV-H LTR-Associating 1
- HL, Hearing loss
- KCNQ3, Potassium Voltage-Gated Channel Subfamily Q Member 3
- Missense mutation
- NGS, next generation sequencing
- NSHL, Non-syndromic hearing loss
- Non-syndromic hearing loss
- PROVEAN, Protein Variation Effect Analyzer
- PolyPhen-2, Polymorphism Phenotyping v2
- RFLP, restriction fragment length polymorphism
- ROH, runs of homozygosity
- RT-PCR, reverse transcription PCR
- RT-qPCR, quantitative reverse transcription PCR
- SAM, Sequence Alignment/Map
- SIFT, Sorting Intolerant From Tolerant
- SJL, Swiss Jim Lambert
- SPATA13, Spermatogenesis Associated 13
- ST3GAL1, ST3 Beta-Galactoside Alpha-2,3-Sialyltransferase 1
- TMEM59, Transmembrane Protein 59
- UAE, United Arab Emirates
- VariMAT, Variation and Mutation Annotation Toolkit
- WES, Whole exome sequencing
- Whole exome sequencing
- dpSNP, Single Nucleotide Polymorphism Database
- gEAR, gene Expression Analysis Resource
- gnomAD, genome aggregation database
- qPCR, quantitative PCR
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Affiliation(s)
- Mona Mahfood
- Department of Applied Biology, College of Sciences, University of Sharjah, Sharjah, United Arab Emirates
| | - Jihen Chouchen
- Human Genetics and Stem Cell Research Group, Research Institute of Sciences and Engineering, University of Sharjah, Sharjah, United Arab Emirates
| | - Walaa Kamal Eddine Ahmad Mohamed
- Human Genetics and Stem Cell Research Group, Research Institute of Sciences and Engineering, University of Sharjah, Sharjah, United Arab Emirates
| | - Abdullah Al Mutery
- Department of Applied Biology, College of Sciences, University of Sharjah, Sharjah, United Arab Emirates.,Human Genetics and Stem Cell Research Group, Research Institute of Sciences and Engineering, University of Sharjah, Sharjah, United Arab Emirates
| | - Rania Harati
- Department of Pharmacy Practice and Pharmacotherapeutics, College of Pharmacy, University of Sharjah, Sharjah, United Arab Emirates
| | - Abdelaziz Tlili
- Department of Applied Biology, College of Sciences, University of Sharjah, Sharjah, United Arab Emirates.,Human Genetics and Stem Cell Research Group, Research Institute of Sciences and Engineering, University of Sharjah, Sharjah, United Arab Emirates
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Wang H, Gao Y, Guan J, Lan L, Yang J, Xiong W, Zhao C, Xie L, Yu L, Wang D, Wang Q. Phenotypic Heterogeneity of Post-lingual and/or Milder Hearing Loss for the Patients With the GJB2 c.235delC Homozygous Mutation. Front Cell Dev Biol 2021; 9:647240. [PMID: 33718389 PMCID: PMC7953049 DOI: 10.3389/fcell.2021.647240] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Accepted: 02/08/2021] [Indexed: 01/01/2023] Open
Abstract
Objective To report the phenotypic heterogeneity of GJB2 c.235delC homozygotes associated with post-lingual and/or milder hearing loss, and explore the possible mechanism of these unconditional phenotypes. Methods Mutation screening of GJB2 was performed on all ascertained members from Family 1006983 and three sporadic patients by polymerase chain reaction (PCR) amplification and Sanger sequencing. Next generation sequencing (NGS) was successively performed on some of the affected members and normal controls from Family 1006983 to explore additional possible genetic codes. Reverse transcriptase–quantitative PCR was conducted to test the expression of Connexin30. Results We identified a Chinese autosomal recessive hearing loss family with the GJB2 c.235delC homozygous mutation, affected members from which had post-lingual moderate to profound hearing impairment, and three sporadic patients with post-lingual moderate hearing impairment, instead of congenital profound hearing loss. NGS showed no other particular variants. Overexpression of Connexin30 in some of these cases was verified. Conclusion Post-lingual and/or moderate hearing impairment phenotypes of GJB2 c.235delC homozygotes are not the most common phenotype, revealing the heterogeneity of GJB2 pathogenic mutations. To determine the possible mechanism that rescues part of the hearing or postpones onset age of these cases, more cases are required to confirm both Connexin30 overexpression and the existence of modifier genes.
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Affiliation(s)
- Hongyang Wang
- College of Otolaryngology, Head and Neck Surgery, Chinese People's Liberation Army (PLA) Institute of Otolaryngology, Chinese People's Liberation Army (PLA) General Hospital, Beijing, China
| | - Yun Gao
- College of Otolaryngology, Head and Neck Surgery, Chinese People's Liberation Army (PLA) Institute of Otolaryngology, Chinese People's Liberation Army (PLA) General Hospital, Beijing, China.,National Clinical Research Center for Otolaryngologic Diseases, Beijing, China.,Key Lab of Hearing Impairment Science of Ministry of Education, Beijing, China.,Key Lab of Hearing Impairment Prevention and Treatment of Beijing, Beijing, China
| | - Jing Guan
- College of Otolaryngology, Head and Neck Surgery, Chinese People's Liberation Army (PLA) Institute of Otolaryngology, Chinese People's Liberation Army (PLA) General Hospital, Beijing, China.,National Clinical Research Center for Otolaryngologic Diseases, Beijing, China.,Key Lab of Hearing Impairment Science of Ministry of Education, Beijing, China.,Key Lab of Hearing Impairment Prevention and Treatment of Beijing, Beijing, China
| | - Lan Lan
- College of Otolaryngology, Head and Neck Surgery, Chinese People's Liberation Army (PLA) Institute of Otolaryngology, Chinese People's Liberation Army (PLA) General Hospital, Beijing, China.,National Clinical Research Center for Otolaryngologic Diseases, Beijing, China.,Key Lab of Hearing Impairment Science of Ministry of Education, Beijing, China.,Key Lab of Hearing Impairment Prevention and Treatment of Beijing, Beijing, China
| | - Ju Yang
- College of Otolaryngology, Head and Neck Surgery, Chinese People's Liberation Army (PLA) Institute of Otolaryngology, Chinese People's Liberation Army (PLA) General Hospital, Beijing, China.,National Clinical Research Center for Otolaryngologic Diseases, Beijing, China.,Key Lab of Hearing Impairment Science of Ministry of Education, Beijing, China.,Key Lab of Hearing Impairment Prevention and Treatment of Beijing, Beijing, China
| | - Wenping Xiong
- College of Otolaryngology, Head and Neck Surgery, Chinese People's Liberation Army (PLA) Institute of Otolaryngology, Chinese People's Liberation Army (PLA) General Hospital, Beijing, China.,National Clinical Research Center for Otolaryngologic Diseases, Beijing, China.,Key Lab of Hearing Impairment Science of Ministry of Education, Beijing, China.,Key Lab of Hearing Impairment Prevention and Treatment of Beijing, Beijing, China
| | - Cui Zhao
- College of Otolaryngology, Head and Neck Surgery, Chinese People's Liberation Army (PLA) Institute of Otolaryngology, Chinese People's Liberation Army (PLA) General Hospital, Beijing, China.,National Clinical Research Center for Otolaryngologic Diseases, Beijing, China.,Key Lab of Hearing Impairment Science of Ministry of Education, Beijing, China.,Key Lab of Hearing Impairment Prevention and Treatment of Beijing, Beijing, China
| | - Linyi Xie
- College of Otolaryngology, Head and Neck Surgery, Chinese People's Liberation Army (PLA) Institute of Otolaryngology, Chinese People's Liberation Army (PLA) General Hospital, Beijing, China.,National Clinical Research Center for Otolaryngologic Diseases, Beijing, China.,Key Lab of Hearing Impairment Science of Ministry of Education, Beijing, China.,Key Lab of Hearing Impairment Prevention and Treatment of Beijing, Beijing, China
| | - Lan Yu
- College of Otolaryngology, Head and Neck Surgery, Chinese People's Liberation Army (PLA) Institute of Otolaryngology, Chinese People's Liberation Army (PLA) General Hospital, Beijing, China.,National Clinical Research Center for Otolaryngologic Diseases, Beijing, China.,Key Lab of Hearing Impairment Science of Ministry of Education, Beijing, China.,Key Lab of Hearing Impairment Prevention and Treatment of Beijing, Beijing, China
| | - Dayong Wang
- College of Otolaryngology, Head and Neck Surgery, Chinese People's Liberation Army (PLA) Institute of Otolaryngology, Chinese People's Liberation Army (PLA) General Hospital, Beijing, China.,National Clinical Research Center for Otolaryngologic Diseases, Beijing, China.,Key Lab of Hearing Impairment Science of Ministry of Education, Beijing, China.,Key Lab of Hearing Impairment Prevention and Treatment of Beijing, Beijing, China
| | - Qiuju Wang
- College of Otolaryngology, Head and Neck Surgery, Chinese People's Liberation Army (PLA) Institute of Otolaryngology, Chinese People's Liberation Army (PLA) General Hospital, Beijing, China.,National Clinical Research Center for Otolaryngologic Diseases, Beijing, China.,Key Lab of Hearing Impairment Science of Ministry of Education, Beijing, China.,Key Lab of Hearing Impairment Prevention and Treatment of Beijing, Beijing, China
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8
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Nisenbaum E, Prentiss S, Yan D, Nourbakhsh A, Smeal M, Holcomb M, Cejas I, Telischi F, Liu XZ. Screening Strategies for Deafness Genes and Functional Outcomes in Cochlear Implant Patients. Otol Neurotol 2021; 42:180-187. [PMID: 33885265 PMCID: PMC9237809 DOI: 10.1097/mao.0000000000002969] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
OBJECTIVES To review the current state of knowledge about the influence of specific genetic mutations that cause sensorineural hearing loss (SNHL) on cochlear implant (CI) functional outcomes, and how this knowledge may be integrated into clinical practice. A multistep and sequential population-based genetic algorithm suitable for the identification of congenital SNHL mutations before CI placement is also examined. DATA SOURCES, STUDY SELECTION A review was performed of the English literature from 2000 to 2019 using PubMed regarding the influence of specific mutations on CI outcomes and the use of next-generation sequencing for genetic screening of CI patients. CONCLUSION CI is an effective habilitation option for patients with severe-profound congenital SNHL. However, it is well known that CI outcomes show substantial inter-patient variation. Recent advances in genetic studies have improved our understanding of genotype-phenotype relationships for many of the mutations underlying congenital SNHL, and have explored how these relationships may account for some of the variance seen in CI performance outcomes. A sequential genetic screening strategy utilizing next-generation sequencing-based population-specific gene panels may allow for more efficient mutation identification before CI placement. Understanding the relationships between specific mutations and CI outcomes along with integrating routine comprehensive genetic testing into pre-CI evaluations will allow for more effective patient counseling and open the door for the development of mutation-specific treatment strategies.
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Affiliation(s)
- Eric Nisenbaum
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, Florida
| | - Sandra Prentiss
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, Florida
| | - Denise Yan
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, Florida
| | - Aida Nourbakhsh
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, Florida
| | - Molly Smeal
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, Florida
| | - Meredith Holcomb
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, Florida
| | - Ivette Cejas
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, Florida
| | - Fred Telischi
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, Florida
| | - Xue Zhong Liu
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, Florida
- Dr. John T. Macdonald Foundation Department of Human Genetics, and John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, Florida
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Buonfiglio P, Bruque CD, Luce L, Giliberto F, Lotersztein V, Menazzi S, Paoli B, Elgoyhen AB, Dalamón V. GJB2 and GJB6 Genetic Variant Curation in an Argentinean Non-Syndromic Hearing-Impaired Cohort. Genes (Basel) 2020; 11:E1233. [PMID: 33096615 PMCID: PMC7589744 DOI: 10.3390/genes11101233] [Citation(s) in RCA: 12] [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: 09/18/2020] [Revised: 10/08/2020] [Accepted: 10/13/2020] [Indexed: 12/13/2022] Open
Abstract
Genetic variants in GJB2 and GJB6 genes are the most frequent causes of hereditary hearing loss among several deaf populations worldwide. Molecular diagnosis enables proper genetic counseling and medical prognosis to patients. In this study, we present an update of testing results in a cohort of Argentinean non-syndromic hearing-impaired individuals. A total of 48 different sequence variants were detected in genomic DNA from patients referred to our laboratory. They were manually curated and classified based on the American College of Medical Genetics and Genomics/Association for Molecular Pathology ACMG/AMP standards and hearing-loss-gene-specific criteria of the ClinGen Hearing Loss Expert Panel. More than 50% of sequence variants were reclassified from their previous categorization in ClinVar. These results provide an accurately interpreted set of variants to be taken into account by clinicians and the scientific community, and hence, aid the precise genetic counseling to patients.
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Affiliation(s)
- Paula Buonfiglio
- Laboratorio de Fisiología y Genética de la Audición, Instituto de Investigaciones en Ingeniería Genética y Biología Molecular “Dr. Héctor N. Torres”, Consejo Nacional de Investigaciones Científicas y Técnicas—INGEBI/CONICET, C1428ADN Ciudad Autónoma de Buenos Aires, Argentina; (P.B.); (A.B.E.)
| | - Carlos D. Bruque
- Centro Nacional de Genética Médica, ANLIS-Malbrán, C1425 Ciudad Autónoma de Buenos Aires, Argentina;
- Instituto de Biología y Medicina Experimental, Consejo Nacional de Investigaciones Científicas y Técnicas—IBYME/CONICET, C1428ADN Ciudad Autónoma de Buenos Aires, Argentina
| | - Leonela Luce
- Laboratorio de Distrofinopatías, Cátedra de Genética, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, C1113AAD Ciudad Autónoma de Buenos Aires, Argentina; (L.L.); (F.G.)
- Instituto de Inmunología, Genética y Metabolismo—INIGEM/CONICET, Universidad de Buenos Aires, C1113AAD Ciudad Autónoma de Buenos Aires, Argentina
| | - Florencia Giliberto
- Laboratorio de Distrofinopatías, Cátedra de Genética, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, C1113AAD Ciudad Autónoma de Buenos Aires, Argentina; (L.L.); (F.G.)
- Instituto de Inmunología, Genética y Metabolismo—INIGEM/CONICET, Universidad de Buenos Aires, C1113AAD Ciudad Autónoma de Buenos Aires, Argentina
| | - Vanesa Lotersztein
- Servicio de Genética, Hospital Militar Central “Dr. Cosme Argerich”, C1426 Ciudad Autónoma de Buenos Aires, Argentina;
| | - Sebastián Menazzi
- Servicio de Genética, Hospital de Clínicas “José de San Martín”, C1120AAR Ciudad Autónoma de Buenos Aires, Argentina;
| | - Bibiana Paoli
- Servicio de Otorrinolaringología Infantil, Hospital de Clínicas “José de San Martín”, C1120AAR Ciudad Autónoma de Buenos Aires, Argentina;
| | - Ana Belén Elgoyhen
- Laboratorio de Fisiología y Genética de la Audición, Instituto de Investigaciones en Ingeniería Genética y Biología Molecular “Dr. Héctor N. Torres”, Consejo Nacional de Investigaciones Científicas y Técnicas—INGEBI/CONICET, C1428ADN Ciudad Autónoma de Buenos Aires, Argentina; (P.B.); (A.B.E.)
- Departamento de Farmacología, Facultad de Medicina, Universidad de Buenos Aires, C1121ABG Ciudad Autónoma de Buenos Aires, Argentina
| | - Viviana Dalamón
- Laboratorio de Fisiología y Genética de la Audición, Instituto de Investigaciones en Ingeniería Genética y Biología Molecular “Dr. Héctor N. Torres”, Consejo Nacional de Investigaciones Científicas y Técnicas—INGEBI/CONICET, C1428ADN Ciudad Autónoma de Buenos Aires, Argentina; (P.B.); (A.B.E.)
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10
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Moisan S, Le Nabec A, Quillévéré A, Le Maréchal C, Férec C. Characterization of GJB2 cis-regulatory elements in the DFNB1 locus. Hum Genet 2019; 138:1275-1286. [PMID: 31586237 DOI: 10.1007/s00439-019-02068-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2019] [Accepted: 09/29/2019] [Indexed: 11/28/2022]
Abstract
Although most disease-causing variants are within coding region of genes, it is now well established that cis-acting regulatory sequences, depending on 3D-chromatin organization, are required for temporal and spatial control of gene expression. Disruptions of such regulatory elements and/or chromatin conformation are likely to play a critical role in human genetic disease. Hence, recurrent monoallelic cases, who present the most common hereditary type of nonsyndromic hearing loss (i.e., DFNB1), carry only one identified pathogenic allele. This strongly suggests the presence of uncharacterized distal cis-acting elements in the missing allele. Here within, we study the spatial organization of a large DFNB1 locus encompassing the gap junction protein beta 2 (GJB2) gene, the most frequently mutated gene in this inherited hearing loss phenotype, with the chromosome conformation capture carbon copy technology (5C). By combining this approach with functional activity reporter assays and mapping of CCCTC-binding factor (CTCF) along the DFNB1 locus, we identify a novel set of cooperating GJB2 cis-acting elements and suggest a DFNB1 three-dimensional looping regulation model.
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Affiliation(s)
- Stéphanie Moisan
- Laboratoire de Génétique Moléculaire et d'Histocompatibilité, CHRU de Brest, Bretagne, Brest, France. .,Univ Brest, Inserm, EFS UMR 1078, GGB, 29200, Brest, France.
| | - Anaïs Le Nabec
- Univ Brest, Inserm, EFS UMR 1078, GGB, 29200, Brest, France
| | | | - Cédric Le Maréchal
- Laboratoire de Génétique Moléculaire et d'Histocompatibilité, CHRU de Brest, Bretagne, Brest, France.,Univ Brest, Inserm, EFS UMR 1078, GGB, 29200, Brest, France
| | - Claude Férec
- Laboratoire de Génétique Moléculaire et d'Histocompatibilité, CHRU de Brest, Bretagne, Brest, France. .,Univ Brest, Inserm, EFS UMR 1078, GGB, 29200, Brest, France.
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11
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Posukh OL, Zytsar MV, Bady-Khoo MS, Danilchenko VY, Maslova EA, Barashkov NA, Bondar AA, Morozov IV, Maximov VN, Voevoda MI. Unique Mutational Spectrum of the GJB2 Gene and its Pathogenic Contribution to Deafness in Tuvinians (Southern Siberia, Russia): A High Prevalence of Rare Variant c.516G>C (p.Trp172Cys). Genes (Basel) 2019; 10:E429. [PMID: 31195736 PMCID: PMC6627114 DOI: 10.3390/genes10060429] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2019] [Revised: 05/30/2019] [Accepted: 06/03/2019] [Indexed: 01/09/2023] Open
Abstract
Mutations in the GJB2 gene are the main cause for nonsyndromic autosomal recessive deafness 1A (DFNB1A) in many populations. GJB2 mutational spectrum and pathogenic contribution are widely varying in different populations. Significant efforts have been made worldwide to define DFNB1A molecular epidemiology, but this issue still remains open for some populations. The main aim of study is to estimate the DFNB1A prevalence and GJB2 mutational spectrum in Tuvinians-an indigenous population of the Tyva Republic (Southern Siberia, Russia). Sanger sequencing was applied to analysis of coding (exon 2) and non-coding regions of GJB2 in a cohort of Tuvinian patients with hearing impairments (n = 220) and ethnically matched controls (n = 157). Diagnosis of DFNB1A was established for 22.3% patients (28.8% of familial vs 18.6% of sporadic cases). Our results support that patients with monoallelic GJB2 mutations (8.2%) are coincidental carriers. Recessive mutations p.Trp172Cys, c.-23+1G>A, c.235delC, c.299_300delAT, p.Val37Ile and several benign variants were found in examined patients. A striking finding was a high prevalence of rare variant p.Trp172Cys (c.516G>C) in Tuvinians accounting for 62.9% of all mutant GJB2 alleles and a carrier frequency of 3.8% in controls. All obtained data provide important targeted information for genetic counseling of affected Tuvinian families and enrich current information on variability of GJB2 worldwide.
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Affiliation(s)
- Olga L Posukh
- Federal Research Center Institute of Cytology and Genetics, Siberian Branch of the Russian Academy of Sciences, 630090 Novosibirsk, Russia.
- Novosibirsk State University, 630090 Novosibirsk, Russia.
| | - Marina V Zytsar
- Federal Research Center Institute of Cytology and Genetics, Siberian Branch of the Russian Academy of Sciences, 630090 Novosibirsk, Russia.
| | - Marita S Bady-Khoo
- Research Institute of Medical-Social Problems and Management of the Republic of Tyva, 667000 Kyzyl, Russia.
- Perinatal Center of the Republic of Tyva, 667000 Kyzyl, Russia.
| | - Valeria Yu Danilchenko
- Federal Research Center Institute of Cytology and Genetics, Siberian Branch of the Russian Academy of Sciences, 630090 Novosibirsk, Russia.
| | - Ekaterina A Maslova
- Federal Research Center Institute of Cytology and Genetics, Siberian Branch of the Russian Academy of Sciences, 630090 Novosibirsk, Russia.
- Novosibirsk State University, 630090 Novosibirsk, Russia.
| | - Nikolay A Barashkov
- Yakut Scientific Centre of Complex Medical Problems, 677019 Yakutsk, Russia.
- M.K. Ammosov North-Eastern Federal University, 677027 Yakutsk, Russia.
| | - Alexander A Bondar
- Institute of Chemical Biology and Fundamental Medicine, Siberian Branch of the Russian Academy of Sciences, 630090 Novosibirsk, Russia.
| | - Igor V Morozov
- Novosibirsk State University, 630090 Novosibirsk, Russia.
- Institute of Chemical Biology and Fundamental Medicine, Siberian Branch of the Russian Academy of Sciences, 630090 Novosibirsk, Russia.
| | - Vladimir N Maximov
- Federal Research Center Institute of Cytology and Genetics, Siberian Branch of the Russian Academy of Sciences, 630090 Novosibirsk, Russia.
- Novosibirsk State University, 630090 Novosibirsk, Russia.
| | - Michael I Voevoda
- Federal Research Center Institute of Cytology and Genetics, Siberian Branch of the Russian Academy of Sciences, 630090 Novosibirsk, Russia.
- Novosibirsk State University, 630090 Novosibirsk, Russia.
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12
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Advances in cochlear implantation for hereditary deafness caused by common mutations in deafness genes. JOURNAL OF BIO-X RESEARCH 2019. [DOI: 10.1097/jbr.0000000000000037] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
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13
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Xie L, Chen S, Xu K, Cao HY, Du AN, Bai X, Sun Y, Kong WJ. Reduced postnatal expression of cochlear Connexin26 induces hearing loss and affects the developmental status of pillar cells in a dose-dependent manner. Neurochem Int 2019; 128:196-205. [PMID: 31034913 DOI: 10.1016/j.neuint.2019.04.012] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Revised: 04/17/2019] [Accepted: 04/19/2019] [Indexed: 10/26/2022]
Abstract
Mutations in the GJB2 gene (which encodes Connexin26 (Cx26)) are the most common cause of non-syndromic deafness. Previous studies showed that an extensive knockout of the Gjb2 gene in cochlear epithelium can cause severe deafness, significant hair cell (HC) loss and failure of pillar cells (a type of supporting cell, PCs) to differentiate in mice. This study aimed to establish different mouse models with gradient reductions of cochlear Cx26 expression and to investigate the effect of different reduced levels of cochlear Cx26 expression on hearing and development of PCs. According to the reduction in the levels of cochlear Cx26, these models were named high knockdown (KD), middle KD and low KD group. In the low KD group, the mice showed normal hearing and well-developed PCs. In the high KD group, up to 90 percent of supporting cells (SCs) lost Cx26 expression. These mice exhibited severe deafness, rapid hair cell degeneration and juvenile PCs. In the middle KD group, nearly half of SCs lost Cx26 expression. However, these mice showed a moderate deafness and a late-onset hair cell loss. Moreover, nearly all the PCs in mice of this group were in a partially differentiated state. These results indicated that reduction of postnatal expression of cochlear Cx26 induces hearing loss in a dose-dependent manner. Null Cx26 in a few SCs affects the developmental status of PCs and the hair cell degeneration pattern. The abnormal developmental status of PCs may be a potential cause of Gjb2-related hearing loss.
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Affiliation(s)
- Le Xie
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China
| | - Sen Chen
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China
| | - Kai Xu
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China
| | - Hai-Yan Cao
- Department of Ultrasound, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China
| | - An-Na Du
- Centre of Instrumental Analysis and Metrology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, 430071, China
| | - Xue Bai
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China
| | - Yu Sun
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China.
| | - Wei-Jia Kong
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China; Institute of Otorhinolaryngology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China.
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14
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Erdenechuluun J, Lin YH, Ganbat K, Bataakhuu D, Makhbal Z, Tsai CY, Lin YH, Chan YH, Hsu CJ, Hsu WC, Chen PL, Wu CC. Unique spectra of deafness-associated mutations in Mongolians provide insights into the genetic relationships among Eurasian populations. PLoS One 2018; 13:e0209797. [PMID: 30576380 PMCID: PMC6303056 DOI: 10.1371/journal.pone.0209797] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2018] [Accepted: 12/11/2018] [Indexed: 02/07/2023] Open
Abstract
Genetic factors are an important cause of idiopathic sensorineural hearing impairment (SNHI). From the epidemiological perspective, mutations of three deafness genes: GJB2, SLC26A4, and MT-RNR1, are much more prevalent than those of other genes worldwide. However, mutation spectra of common deafness genes differ remarkably across different populations. Here, we performed comprehensive genetic examination and haplotype analyses in 188 unrelated Mongolian families with idiopathic SNHI, and compared their mutation spectra and haplotypes to those of other European and Asian cohorts. We confirmed genetic diagnoses in 18 (9.6%) of the 188 families, including 13 with bi-allelic GJB2 mutations, three with bi-allelic SLC26A4 mutations, and two with homoplasmic MT-RNR1 m.1555A>G mutation. Moreover, mono-allelic mutations were identified in 17 families (9.0%), including 14 with mono-allelic GJB2 mutations and three with mono-allelic SLC26A4 mutations. Interestingly, three GJB2 mutations prevalent in other populations, including c.35delG in Caucasians, c.235delC in East Asians, and c.-23+1G>A in Southwest and South Asians, were simultaneously detected in Mongolian patients. Haplotype analyses further confirmed founder effects for each of the three mutations, indicating that each mutation derived from its ancestral origin independently. By demonstrating the unique spectra of deafness-associated mutations, our findings may have important clinical and scientific implications for refining the molecular diagnostics of SNHI in Mongolian patients, and for elucidating the genetic relationships among Eurasian populations.
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Affiliation(s)
- Jargalkhuu Erdenechuluun
- Department of Otolaryngology, Mongolian National University of Medical Sciences, Ulaanbaatar, Mongolia
- The EMJJ Otolaryngology Hospital, Ulaanbaatar, Mongolia
| | - Yin-Hung Lin
- Department of Otolaryngology, National Taiwan University Hospital, Taipei, Taiwan
- Graduate Institute of Medical Genomics and Proteomics, National Taiwan University College of Medicine, Taipei, Taiwan
| | - Khongorzul Ganbat
- The EMJJ Otolaryngology Hospital, Ulaanbaatar, Mongolia
- Department of Otolaryngology, National Center for Maternal and Child Health, Ulaanbaatar, Mongolia
| | - Delgermaa Bataakhuu
- Department of Otolaryngology, National Center for Maternal and Child Health, Ulaanbaatar, Mongolia
| | - Zaya Makhbal
- Department of Otolaryngology, National Center for Maternal and Child Health, Ulaanbaatar, Mongolia
| | - Cheng-Yu Tsai
- Department of Otolaryngology, National Taiwan University Hospital, Taipei, Taiwan
- Graduate Institute of Medical Genomics and Proteomics, National Taiwan University College of Medicine, Taipei, Taiwan
| | - Yi-Hsin Lin
- Department of Otolaryngology, National Taiwan University Hospital, Taipei, Taiwan
| | - Yen-Hui Chan
- Department of Otolaryngology, National Taiwan University Hospital, Taipei, Taiwan
| | - Chuan-Jen Hsu
- Department of Otolaryngology, National Taiwan University Hospital, Taipei, Taiwan
| | - Wei-Chung Hsu
- Department of Otolaryngology, National Taiwan University Hospital, Taipei, Taiwan
| | - Pei-Lung Chen
- Graduate Institute of Medical Genomics and Proteomics, National Taiwan University College of Medicine, Taipei, Taiwan
- Department of Medical Genetics, National Taiwan University Hospital, Taipei, Taiwan
| | - Chen-Chi Wu
- Department of Otolaryngology, National Taiwan University Hospital, Taipei, Taiwan
- Department of Medical Genetics, National Taiwan University Hospital, Taipei, Taiwan
- * E-mail:
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Balta B, Gundogdu R, Erdogan M, Alisik M, Kiraz A, Ozcan I, Erel O. Decreased disulphide/thiol ratio in patients with autosomal recessive non-syndromic hearing loss. Int J Pediatr Otorhinolaryngol 2018; 112:188-192. [PMID: 30055731 DOI: 10.1016/j.ijporl.2018.07.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/12/2018] [Revised: 07/05/2018] [Accepted: 07/09/2018] [Indexed: 11/26/2022]
Abstract
INTRODUCTION Oxidative stress plays a key role in the formation of age-related, noise-induced and drug-induced hearing loss. Thiols are organic compounds which can react with free radicals to protect against tissue and cell damage caused by reactive oxygen. There are no studies in literature on the association between autosomal recessive non-syndromic hearing loss(ARNSHL) including GJB2 and non-GJB2 mutations and thiol-disulphide balance. In this study, we aim to assess whether thiol-disulphide balance is disrupted in patients with ARNSHL. METHODS Thirty-one ARNSHL patients and thirty-one healthy controls were included in this study. Patients whose parents were first degree cousins and who had at least two congenital hearing loss in the same family were included in the study. Audiological tests included air - bone pure tone audiometry and auditory brain stem response. GJB2 gene analysis was performed using sanger sequence method. Tests of thiol/disulphide homeostasis were conducted using the automated spectrophotometric method. We first investigated whether there was a significant difference between ARNSHL patients and healthy controls. Then, in order to determine the differential effect of the GJB2 gene mutations and non-GJB2 gene mutations on the thiol-disulphide balance, subjects were divided into three groups: Group 1 included patients with GJB2 mutations; Group 2 included patients with non-GJB2 mutations; Group 3 included healthy subjects. RESULTS Patients with ARNSHL had significantly higher native thiol (411.6 ± 54.3 μmol/l vs. 368.0 ± 64.3 μmol/l, p = 0.006), total thiol levels (440.3 ± 56.2 μmol/l vs. 402.4 ± 65.9 μmol/l, p = 0.018), and lower disulphide levels (14.3 ± 5.7 μmol/l) vs. (17.1 ± 4.9 μmol/l), (p = 0.043) compared to the control group. Moreover, disulphide /native thiol (p < 0.001) and disulphide/total thiol (p < 0.001) were also detected lower in the ARNSHL group compared to the control group. Thiol-disulphide hemostasis parameters between all three groups showed that the native thiol and total thiol were increased in the Group 1 and Group 2. The disulphide levels decreased in Group 1 and 2, although not statistically significant. CONCLUSION It was shown that thiol levels increased and disulphide levels decreased in patients with autosomal recessive non-syndromic hearing loss. It also may suggest that there is a reverse association between ARNSHL and oxidative stress. Further studies are needed on whether or not ARNSHL cause oxidative stress limited to the inner ear and cochlea.
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Affiliation(s)
- Burhan Balta
- Department of Medical Genetics, Kayseri Training and Research Hospital, Kayseri, Turkey.
| | - Ramazan Gundogdu
- Department of Otorhinolaryngology, Kayseri Training and Research Hospital, Kayseri, Turkey.
| | - Murat Erdogan
- Department of Medical Genetics, Kayseri Training and Research Hospital, Kayseri, Turkey.
| | - Murat Alisik
- Department of Biochemistry, Yıldırım Beyazıd University, Ankara, Turkey.
| | - Aslihan Kiraz
- Department of Medical Genetics, Kayseri Training and Research Hospital, Kayseri, Turkey.
| | - Ibrahim Ozcan
- Department of Otorhinolaryngology, Kayseri Training and Research Hospital, Kayseri, Turkey.
| | - Ozcan Erel
- Department of Biochemistry, Yıldırım Beyazıd University, Ankara, Turkey.
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Roesch S, Bernardinelli E, Nofziger C, Tóth M, Patsch W, Rasp G, Paulmichl M, Dossena S. Functional Testing of SLC26A4 Variants-Clinical and Molecular Analysis of a Cohort with Enlarged Vestibular Aqueduct from Austria. Int J Mol Sci 2018; 19:ijms19010209. [PMID: 29320412 PMCID: PMC5796158 DOI: 10.3390/ijms19010209] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2017] [Revised: 12/20/2017] [Accepted: 12/28/2017] [Indexed: 12/29/2022] Open
Abstract
The prevalence and spectrum of sequence alterations in the SLC26A4 gene, which codes for the anion exchanger pendrin, are population-specific and account for at least 50% of cases of non-syndromic hearing loss associated with an enlarged vestibular aqueduct. A cohort of nineteen patients from Austria with hearing loss and a radiological alteration of the vestibular aqueduct underwent Sanger sequencing of SLC26A4 and GJB2, coding for connexin 26. The pathogenicity of sequence alterations detected was assessed by determining ion transport and molecular features of the corresponding SLC26A4 protein variants. In this group, four uncharacterized sequence alterations within the SLC26A4 coding region were found. Three of these lead to protein variants with abnormal functional and molecular features, while one should be considered with no pathogenic potential. Pathogenic SLC26A4 sequence alterations were only found in 12% of patients. SLC26A4 sequence alterations commonly found in other Caucasian populations were not detected. This survey represents the first study on the prevalence and spectrum of SLC26A4 sequence alterations in an Austrian cohort and further suggests that genetic testing should always be integrated with functional characterization and determination of the molecular features of protein variants in order to unequivocally identify or exclude a causal link between genotype and phenotype.
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Affiliation(s)
- Sebastian Roesch
- Department of Otorhinolaryngology, Head and Neck Surgery, Paracelsus Medical University, Müllner Hauptstraße 48, A-5020 Salzburg, Austria.
| | - Emanuele Bernardinelli
- Institute of Pharmacology and Toxicology, Paracelsus Medical University, Strubergasse 21, A-5020 Salzburg, Austria.
| | - Charity Nofziger
- PharmGenetix Gmbh, Sonystrasse 20, A-5081 Niederalm Anif, Austria.
| | - Miklós Tóth
- Department of Otorhinolaryngology, Head & Neck Surgery and Oncology, University Medical Center Hamburg-Eppendorf, Martinistraße 52, D-20251 Hamburg, Germany.
| | - Wolfgang Patsch
- Institute of Pharmacology and Toxicology, Paracelsus Medical University, Strubergasse 21, A-5020 Salzburg, Austria.
| | - Gerd Rasp
- Department of Otorhinolaryngology, Head and Neck Surgery, Paracelsus Medical University, Müllner Hauptstraße 48, A-5020 Salzburg, Austria.
| | - Markus Paulmichl
- Center for Health and Bioresources, Austrian Institute of Technology, Muthgasse 11, A-1190 Vienna, Austria.
| | - Silvia Dossena
- Institute of Pharmacology and Toxicology, Paracelsus Medical University, Strubergasse 21, A-5020 Salzburg, Austria.
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del Castillo FJ, del Castillo I. DFNB1 Non-syndromic Hearing Impairment: Diversity of Mutations and Associated Phenotypes. Front Mol Neurosci 2017; 10:428. [PMID: 29311818 PMCID: PMC5743749 DOI: 10.3389/fnmol.2017.00428] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Accepted: 12/07/2017] [Indexed: 02/02/2023] Open
Abstract
The inner ear is a very complex sensory organ whose development and function depend on finely balanced interactions among diverse cell types. The many different kinds of inner ear supporting cells play the essential roles of providing physical and physiological support to sensory hair cells and of maintaining cochlear homeostasis. Appropriately enough, the gene most commonly mutated among subjects with hereditary hearing impairment (HI), GJB2, encodes the connexin-26 (Cx26) gap-junction channel protein that underlies both intercellular communication among supporting cells and homeostasis of the cochlear fluids, endolymph and perilymph. GJB2 lies at the DFNB1 locus on 13q12. The specific kind of HI associated with this locus is caused by recessively-inherited mutations that inactivate the two alleles of the GJB2 gene, either in homozygous or compound heterozygous states. We describe the many diverse classes of genetic alterations that result in DFNB1 HI, such as large deletions that either destroy the GJB2 gene or remove a regulatory element essential for GJB2 expression, point mutations that interfere with promoter function or splicing, and small insertions or deletions and nucleotide substitutions that target the GJB2 coding sequence. We focus on how these alterations disrupt GJB2 and Cx26 functions and on their different effects on cochlear development and physiology. We finally discuss the diversity of clinical features of DFNB1 HI as regards severity, age of onset, inner ear malformations and vestibular dysfunction, highlighting the areas where future research should be concentrated.
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Affiliation(s)
- Francisco J. del Castillo
- Servicio de Genética, Hospital Universitario Ramón y Cajal, IRYCIS, Madrid, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Madrid, Spain
| | - Ignacio del Castillo
- Servicio de Genética, Hospital Universitario Ramón y Cajal, IRYCIS, Madrid, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Madrid, Spain
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Tlili A, Al Mutery A, Kamal Eddine Ahmad Mohamed W, Mahfood M, Hadj Kacem H. Prevalence of GJB2 Mutations in Affected Individuals from United Arab Emirates with Autosomal Recessive Nonsyndromic Hearing Loss. Genet Test Mol Biomarkers 2017; 21:686-691. [PMID: 29016196 DOI: 10.1089/gtmb.2017.0130] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
AIM Mutations in the gap junction protein beta 2 (GJB2) gene are responsible for more cases of nonsyndromic recessive hearing loss than any other gene. The purpose of our study was to evaluate the prevalence of GJB2 mutations among affected individuals from United Arab Emirates (UAE). METHODS There were 50 individuals diagnosed with hereditary hearing loss and 120 healthy individuals enrolled in the study. The Sanger sequencing method was used to screen the GJB2 coding region in all affected individuals. The c.-1G>A variant was determined by the polymerase chain reaction-restriction fragment length polymorphism method in normal individuals. RESULTS AND DISCUSSION Nine cases with bi-allelic mutations and three cases with mono-allelic mutations were detected in 12 out of 50 patients (24%). The homozygous mutation c.35delG was identified as the cause of hearing loss in six participants (12%). The mutation c.506G>A was identified in three affected individuals (6%). The allelic frequency (14%) and low percentage of individuals that were homozygous (2%) for the c.35delG mutation suggest that there are other genes responsible for nonsyndromic deafness in the UAE population. The results reported here are a preliminary step in collecting epidemiological data regarding autosomal recessive nonsyndromic hearing loss related to GJB2 gene mutations among the UAE population. CONCLUSION The c.35delG mutation of the GJB2 gene is the most frequently seen causative mutation in the UAE and is followed by the p.Cys169Tyr mutation.
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Affiliation(s)
- Abdelaziz Tlili
- 1 Department of Applied Biology, College of Sciences, University of Sharjah , Sharjah, United Arab Emirates .,2 Human Genetics and Stem Cell Laboratory, Research Institute of Sciences and Engineering, University of Sharjah , Sharjah, United Arab Emirates
| | - Abdullah Al Mutery
- 1 Department of Applied Biology, College of Sciences, University of Sharjah , Sharjah, United Arab Emirates
| | | | - Mona Mahfood
- 1 Department of Applied Biology, College of Sciences, University of Sharjah , Sharjah, United Arab Emirates
| | - Hassen Hadj Kacem
- 1 Department of Applied Biology, College of Sciences, University of Sharjah , Sharjah, United Arab Emirates .,2 Human Genetics and Stem Cell Laboratory, Research Institute of Sciences and Engineering, University of Sharjah , Sharjah, United Arab Emirates
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Pshennikova VG, Barashkov NA, Solovyev AV, Romanov GP, Diakonov EE, Sazonov NN, Morozov IV, Bondar AA, Posukh OL, Dzhemileva LU, Khusnutdinova EK, Tomsky MI, Fedorova SA. Analysis of GJB6 (Сx30) and GJB3 (Сx31) genes in deaf patients with monoallelic mutations in GJB2 (Сx26) gene in the Sakha Republic (Yakutia). RUSS J GENET+ 2017. [DOI: 10.1134/s1022795417030103] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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20
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Bliznetz EA, Kanivets IV, Polyakov AV. DNA copy number analysis of the DFNB1 hereditary hearing loss locus. RUSS J GENET+ 2017. [DOI: 10.1134/s1022795417050027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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21
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Nishio SY, Usami SI. Outcomes of cochlear implantation for the patients with specific genetic etiologies: a systematic literature review. Acta Otolaryngol 2017; 137:730-742. [PMID: 28498079 DOI: 10.1080/00016489.2016.1276303] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
CONCLUSION Most of the cases with gene mutations of intra-cochlear etiology showed relatively good CI outcomes. To progress toward more solid evidence-based CI intervention, a greater number of reports including CI outcomes for specific gene mutations are desired. BACKGROUND Cochlear implantation (CI) is the most important and effective treatment for patients with profound sensorineural hearing loss. However, the outcomes of CI vary among patients. One of the reasons of this heterogeneous outcome for cochlear implantation is thought to be the heterogeneous nature of hearing loss. Indeed, genetic factors, the most common etiology in severe-to-profound hearing loss, might be one of the key determinants of outcomes for CI and electric acoustic stimulation (EAS). Patients with genetic causes involving an 'intra-cochlear' etiology show good CI/EAS outcomes. REVIEW This review article aimed to summarize the reports on CI/EAS outcomes in patients with special genetic causes as well as to assist in future clinical decision-making. Most of the cases were suspected of an intra-cochlear etiology, such as those with GJB2, SLC26A4, and OTOF mutations, which showed relatively good CI outcomes. However, there have only been a limited number of reports on patients with other gene mutations.
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Affiliation(s)
- Shin-ya Nishio
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Nagano, Japan
| | - Shin-ichi Usami
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Nagano, Japan
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22
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Tsukada K, Nishio SY, Hattori M, Usami SI. Ethnic-specific spectrum of GJB2 and SLC26A4 mutations: their origin and a literature review. Ann Otol Rhinol Laryngol 2015; 124 Suppl 1:61S-76S. [PMID: 25999548 DOI: 10.1177/0003489415575060] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE The mutation spectrum of the GJB2 and SLC26A4 genes, the 2 most common genes causing deafness, are known to be ethnic specific. In this study, the spectrum of the reported GJB2 and SLC26A4 mutations in different populations are reviewed and considered from a human migration perspective. METHODS Fifty-two and 17 articles on GJB2 and SLC26A4 mutations, respectively, were reviewed through the PubMed database from April 1996 to September 2014. The 4 most prevalent mutations were selected and compared. A cluster analysis was subsequently performed for these selected mutations. RESULTS The present review of frequent mutations shows the ethnic-specific GJB2 and SLC26A4 gene mutation spectrum. A cluster analysis of the GJB2 and SLC26A4 genes revealed similarities between ethnic populations. CONCLUSION The mutation spectrum reviewed in this study clearly indicated that the frequent mutations in the GJB2 and SLC26A4 genes are consistent with the founder mutation hypothesis. A comparison with the Y-chromosome phylogenetic tree indicated that these mutations may have occurred during human migration.
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Affiliation(s)
- Keita Tsukada
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan
| | - Shin-Ya Nishio
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan Department of Hearing Implant Sciences, Shinshu University School of Medicine, Matsumoto, Japan
| | - Mitsuru Hattori
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan
| | - Shin-Ichi Usami
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan Department of Hearing Implant Sciences, Shinshu University School of Medicine, Matsumoto, Japan
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Tsukada K, Fukuoka H, Usami SI. Vestibular functions of hereditary hearing loss patients with GJB2 mutations. Audiol Neurootol 2015; 20:147-52. [PMID: 25824904 DOI: 10.1159/000368292] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2014] [Accepted: 09/10/2014] [Indexed: 11/19/2022] Open
Abstract
OBJECTIVES Mutations in the GJB2 gene have been of particular interest as it is the most common causative gene for congenital deafness in all populations. Detailed audiological features, including genotype-phenotype correlations, have been well documented. However, in spite of abundant gene as well as protein expression in the vestibular end organs, neither vestibular symptoms nor vestibular functions have yet been elucidated. In the present study, vestibular functions were evaluated in patients diagnosed with GJB2-related deafness. SUBJECTS AND METHODS Vestibular functions were evaluated by caloric test and cervical vestibular evoked myogenic potential (cVEMP) testing in 24 patients with biallelic GJB2 mutations. RESULTS AND DISCUSSION Twenty-one of 23 patients (91.3%) had normal caloric responses and significantly lower cVEMP amplitudes than the control subjects. In the patients who were able to undergo vestibular testing, the mostly normal reactions to caloric testing indicated that the lateral semicircular canal was intact. However, the majority of GJB2 patients showed low cVEMP reactions, indicating a saccular defect.
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Affiliation(s)
- Keita Tsukada
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto City, Japan
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24
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Zonta F, Girotto G, Buratto D, Crispino G, Morgan A, Abdulhadi K, Alkowari M, Badii R, Gasparini P, Mammano F. The p.Cys169Tyr variant of connexin 26 is not a polymorphism. Hum Mol Genet 2015; 24:2641-8. [PMID: 25628337 PMCID: PMC4383868 DOI: 10.1093/hmg/ddv026] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2014] [Accepted: 01/21/2015] [Indexed: 12/31/2022] Open
Abstract
Mutations in the GJB2 gene, which encodes the gap junction protein connexin 26 (Cx26), are the primary cause of hereditary prelingual hearing impairment. Here, the p.Cys169Tyr missense mutation of Cx26 (Cx26C169Y), previously classified as a polymorphism, has been identified as causative of severe hearing loss in two Qatari families. We have analyzed the effect of this mutation using a combination of confocal immunofluorescence microscopy and molecular dynamics simulations. At the cellular level, our results show that the mutant protein fails to form junctional channels in HeLa transfectants despite being correctly targeted to the plasma membrane. At the molecular level, this effect can be accounted for by disruption of the disulfide bridge that Cys169 forms with Cys64 in the wild-type structure (Cx26WT). The lack of the disulfide bridge in the Cx26C169Y protein causes a spatial rearrangement of two important residues, Asn176 and Thr177. In the Cx26WT protein, these residues play a crucial role in the intra-molecular interactions that permit the formation of an intercellular channel by the head-to-head docking of two opposing hemichannels resident in the plasma membrane of adjacent cells. Our results elucidate the molecular pathogenesis of hereditary hearing loss due to the connexin mutation and facilitate the understanding of its role in both healthy and affected individuals.
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Affiliation(s)
- Francesco Zonta
- Dipartimento di Fisica e Astronomia 'G. Galilei', Università di Padova, 35131 Padova, Italy
| | - Giorgia Girotto
- Department of Medical, Surgical and Health Sciences, University of Trieste, 34100 Trieste, Italy
| | - Damiano Buratto
- Dipartimento di Fisica e Astronomia 'G. Galilei', Università di Padova, 35131 Padova, Italy
| | - Giulia Crispino
- Dipartimento di Fisica e Astronomia 'G. Galilei', Università di Padova, 35131 Padova, Italy, Istituto Veneto di Medicina Molecolare, Fondazione per la Ricerca Biomedica Avanzata, 35129 Padova, Italy
| | - Anna Morgan
- Department of Medical, Surgical and Health Sciences, University of Trieste, 34100 Trieste, Italy
| | - Khalid Abdulhadi
- Audiology and Balance Unit, National Program for Early Detection of Hearing Loss, WH, Hamad Medical Corporation (HMC) Doha, Doha, Qatar
| | - Moza Alkowari
- Molecular Genetics Laboratory, Department of Laboratory of Medicine and Pathology, Hamad Medical Corporation (HMC), Doha, Qatar
| | - Ramin Badii
- Molecular Genetics Laboratory, Department of Laboratory of Medicine and Pathology, Hamad Medical Corporation (HMC), Doha, Qatar
| | - Paolo Gasparini
- Department of Medical, Surgical and Health Sciences, University of Trieste, 34100 Trieste, Italy, Medical Genetics, Institute for Maternal and Child Health-IRCCS 'Burlo Garofolo', Trieste, Italy and
| | - Fabio Mammano
- Dipartimento di Fisica e Astronomia 'G. Galilei', Università di Padova, 35131 Padova, Italy, Istituto Veneto di Medicina Molecolare, Fondazione per la Ricerca Biomedica Avanzata, 35129 Padova, Italy, CNR Institute of Cell Biology and Neurobiology, 00015 Monterotondo, Rome, Italy
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Han XH, Fan Y, Wei QJ, Xing GQ, Cao X. Understanding of the molecular evolution of deafness-associated pathogenic mutations of connexin 26. Genetica 2014; 142:555-62. [PMID: 25447126 DOI: 10.1007/s10709-014-9803-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2013] [Accepted: 11/22/2014] [Indexed: 11/28/2022]
Abstract
Connexins (Cxs) were first identified as subunit proteins of the intercellular membrane channels that cluster in the cell communication structures known as gap junctions. Mutations in the gap junction β2 (GJB2) gene encoding connexin 26 (Cx26) have been linked to sporadic and hereditary hearing loss. In some cases, the mechanisms through which these mutations lead to hearing loss have been partly elucidated using cell culture systems and animal models. The goal of this study was to re-assess the pathogenic roles of the GJB2 mutations by combining comparative evolutionary studies. We used Bayesian phylogenetic analyses to determine the relationships among 35 orthologs and to calculate the ancestral sequences of these orthologs. By aligning sequences from the 35 orthologs and their ancestors and categorizing amino acid sites by degree of conservation, we used comparative evolutionary methods to determine potential functionally important amino acid sites in Cx26 and to identify missense changes that are likely to affect function. We identified six conserved regions in Cx26, five of which are located in the Connexin_CCC, and another is in the connexin super family domain. Finally, we identified 51 missense changes that are likely to disrupt function, and the probability of these changes occurring at hydrophilic amino acid residues was twice that of occurring at hydrophobic residues in the trans-membrane regions of Cx26. Our findings, which were obtained by combining comparative evolutionary methods to predict Cx26 mutant function, are consistent with the pathogenic characteristics of Cx26 mutants. This study provides a new pathway for studying the role of aberrant Cx26 in hereditary hearing loss.
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Affiliation(s)
- Xin-Huan Han
- The School of Basic Medical Science, Nanjing Medical University, Nanjing, 210029, People's Republic of China
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26
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Hernández-Juárez AA, Lugo-Trampe JDJ, Campos-Acevedo LD, Lugo-Trampe A, Treviño-González JL, de-la-Cruz-Ávila I, Martínez-de-Villarreal LE. GJB2 and GJB6 mutations are an infrequent cause of autosomal-recessive nonsyndromic hearing loss in residents of Mexico. Int J Pediatr Otorhinolaryngol 2014; 78:2107-12. [PMID: 25288386 DOI: 10.1016/j.ijporl.2014.09.016] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/16/2014] [Revised: 09/12/2014] [Accepted: 09/16/2014] [Indexed: 12/11/2022]
Abstract
OBJECTIVES Mutations in the DFNB1 locus are the most common cause of autosomal-recessive nonsyndromic hearing loss (ARNSHL) worldwide. The aim of this study was to identify the most frequent mutations in patients with ARNSHL who reside in Northeastern Mexico. METHODS We determined the nucleotide sequence the coding region of GJB2 of 78 patients with ARNSHL. Polymerase chain reaction assays were used to detect the GJB2 IVS1+1G>A mutation and deletions within GJB6. RESULTS GJB2 mutations were detected in 9.6% of the alleles, and c.35delG was the most frequent. Six other less-frequent mutations were detected, including an extremely rare variant (c.645_648delTAGA), a novel mutation (c.35G>A), and one of possible Mexican origin (c.34G>T). GJB6 deletions and GJB2 IVS1+1G>A were not detected. CONCLUSIONS These data suggest that mutations in the DFNB1 locus are a rare cause of ARNSHL among the population of Northeastern Mexico. This confirms the genetic heterogeneity of this condition and indicates that further research is required to determine the other mechanisms of pathogenesis of ARNSHL in Mexicans.
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Affiliation(s)
- Aideé Alejandra Hernández-Juárez
- Departamento de Genética, Facultad de Medicina y Hospital Universitario "José E. González", Universidad Autónoma de Nuevo León (UANL), Av. Gonzalitos s/n cruce con Av. Madero, Col. Mitras Centro CP 64460, Monterrey, N.L., México
| | - José de Jesús Lugo-Trampe
- Departamento de Genética, Facultad de Medicina y Hospital Universitario "José E. González", Universidad Autónoma de Nuevo León (UANL), Av. Gonzalitos s/n cruce con Av. Madero, Col. Mitras Centro CP 64460, Monterrey, N.L., México
| | - Luis Daniel Campos-Acevedo
- Departamento de Genética, Facultad de Medicina y Hospital Universitario "José E. González", Universidad Autónoma de Nuevo León (UANL), Av. Gonzalitos s/n cruce con Av. Madero, Col. Mitras Centro CP 64460, Monterrey, N.L., México
| | - Angel Lugo-Trampe
- Centro Mesoamericano de Estudios en Salud Pública y Desastres, Universidad Autónoma de Chiapas (UNACH), Carretera Antiguo Aeropuerto; Pista Principal cruce con Pista Secundaria S/N, Col. Solidaridad 2000, CP 30798, Tapachula, Chis, México
| | - José Luis Treviño-González
- Departamento de Otorrinolaringología, Facultad de Medicina y Hospital Universitario "José E. González", Universidad Autónoma de Nuevo León (UANL), Av. Gonzalitos s/n cruce con Av. Madero, Col. Mitras Centro CP 64460, Monterrey, N.L., México
| | - Israel de-la-Cruz-Ávila
- Servicio de Audiología Pediátrica, Hospital Materno-Infantil, Aldama 460, Col. San Rafael, CP. 67190, Guadalupe, N.L., México
| | - Laura Elia Martínez-de-Villarreal
- Departamento de Genética, Facultad de Medicina y Hospital Universitario "José E. González", Universidad Autónoma de Nuevo León (UANL), Av. Gonzalitos s/n cruce con Av. Madero, Col. Mitras Centro CP 64460, Monterrey, N.L., México.
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Loeza-Becerra F, Rivera-Vega MDR, Martínez-Saucedo M, Gonzalez-Huerta LM, Urueta-Cuellar H, Berrruecos-Villalobos P, Cuevas-Covarrubias S. Particular distribution of the GJB2/GJB6 gene mutations in Mexican population with hearing impairment. Int J Pediatr Otorhinolaryngol 2014; 78:1057-60. [PMID: 24774219 DOI: 10.1016/j.ijporl.2014.04.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/20/2014] [Revised: 03/30/2014] [Accepted: 04/01/2014] [Indexed: 10/25/2022]
Abstract
BACKGROUND Hereditary sensorineural hearing loss (SNHL) is a genetically heterogeneous disorder worldwide. Mutations in the GJB2 gene are a frequent cause of hereditary SNHL. There is a prevalence of certain mutations in various populations which suggests that specific mutations may be influenced by ethnic background. OBJECTIVE To analyze the prevalence of GJB2, GJB6 mutations in several geographic areas of Mexico in patients with hereditary SNHL. MATERIALS AND METHODS One hundred and forty Mexican unrelated propositi with prelingual SNHL were included in the study. All patients had three previous generations born in Mexico and belonged to no specific ethnic group. Analyses of the GJB2 and GJB6 genes and mt.1555A<G were performed in all subjects. RESULTS Twenty-three homozygous mutations, 57 heterozygous mutations, 1 double heterozygous (GJB2/GJB6) and 59 wild-type genotypes in the GJB2 gene were observed. Three patients had the homozygous c.del35 mutation whereas 26 patients were heterozygous for this gene defect. Only one patient with the GJB6 gene deletion was present (it includes the double heterozygous GJB2/GJB6). The mt.1555A>G mutation was not detected. CONCLUSION We found a great variety of mutations depending on the analyzed region in patients with SNHL; 57.86% of patients had affection in one or two alleles in GJB2 or GJB6 genes whereas 42.14% were wild-type. In some cases, allele distribution depended on region. Molecular studies of more genes involved in hereditary non-syndromic SNHL are required to completely confirm the molecular basis of hearing loss in Mexican population.
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Affiliation(s)
- Francisco Loeza-Becerra
- Servicio de Genética, Hospital General de México, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico
| | - María del Refugio Rivera-Vega
- Servicio de Genética, Hospital General de México, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico
| | - Mirna Martínez-Saucedo
- Servicio de Genética, Hospital General de México, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico
| | - Luz María Gonzalez-Huerta
- Servicio de Genética, Hospital General de México, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico
| | - Héctor Urueta-Cuellar
- Servicio de Genética, Hospital General de México, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico
| | - Pedro Berrruecos-Villalobos
- Servicio de Audiología, Hospital General de México, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico
| | - Sergio Cuevas-Covarrubias
- Servicio de Genética, Hospital General de México, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico.
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Javidnia H, Carson N, Awubwa M, Byaruhanga R, Mack D, Vaccani JP. Connexin gene mutations among Ugandan patients with nonsyndromic sensorineural hearing loss. Laryngoscope 2014; 124:E373-6. [PMID: 24706568 DOI: 10.1002/lary.24697] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2013] [Revised: 03/31/2014] [Accepted: 04/02/2014] [Indexed: 11/06/2022]
Abstract
OBJECTIVES/HYPOTHESIS Congenital deafness occurs in approximately 1 in 1,000 live births, and 50% of these cases are hereditary. Connexin mutations have been identified as the most common cause of hereditary hearing loss in many populations. The prevalence of this mutation in African patients has not been adequately studied. The objective of this study was to determine the prevalence of connexin 26 and 30 mutations in a population of hearing-impaired patients from Uganda. STUDY DESIGN This is an observational study. METHODS Coding regions of both GJB2 and GJB6, noncoding exon 1 of GJB2, and 30 nucleotides of intronic sequence bordering the exons were analyzed in 126 subjects from Uganda with confirmed bilateral, severe-to-profound sensorineural hearing loss. All variants were analyzed for possible clinical significance using a combination of database searches and in silico tools. RESULTS Complete sequence data were obtained on 115/126 individuals; 11 had only partial or no results. Only one reported pathogenic variant was found in GJB2 (c.208C>G; p.Pro70Ala) and none in GJB6. Three reported variants and two novel variants within intron 1 of GJB2 and two variants within exon 3 of GJB6 were also found. CONCLUSIONS None of the most common types of deletions in the GJB2 gene (c.35delG, c.167delT or c.235delC) were found in this large cohort of deaf children from Uganda. This prompts a search for genetic causes of deafness among this and other previously studied African populations.
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Affiliation(s)
- Hedyeh Javidnia
- Department of Otolaryngology, Head and Neck Surgery, The Ottawa Hospital, Ottawa, Ontario, Canada
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29
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30
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Schrijver I, Gardner P. Hereditary sensorineural hearing loss: advances in molecular genetics and mutation analysis. Expert Rev Mol Diagn 2014; 6:375-86. [PMID: 16706740 DOI: 10.1586/14737159.6.3.375] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Hearing loss has a genetic etiology in the majority of cases and is very common. The universal newborn hearing screening program, together with remarkable recent progress in the characterization of genes associated with the function of hearing, have resulted in increased demand and exciting possibilities of detecting the molecular basis of hereditary hearing loss through DNA testing. Future molecular diagnostic assays are expected to offer a greater variety of gene-specific tests, as well as combined mutation panels, which will aid in the management of the impressive genetic heterogeneity observed in hereditary hearing loss, especially in individuals with nonsyndromic forms. This review addresses the genetics of hearing loss, discusses the most commonly offered genetic assays for nonsyndromic hearing loss, with advantages and limitations, proposes a practical testing algorithm, and highlights current developments.
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Affiliation(s)
- Iris Schrijver
- Stanford University School of Medicine, Department of Pathology & Pediatrics, L235, 300 Pasteur Drive, Stanford, CA 94305, USA.
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Dalamón V, Florencia Wernert M, Lotersztein V, Craig PO, Diamante RR, Barteik ME, Curet C, Paoli B, Mansilla E, Elgoyhen AB. Identification of four novel connexin 26 mutations in non-syndromic deaf patients: genotype-phenotype analysis in moderate cases. Mol Biol Rep 2013; 40:6945-55. [PMID: 24158611 DOI: 10.1007/s11033-013-2814-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2012] [Accepted: 10/16/2013] [Indexed: 10/26/2022]
Abstract
This paper presents a mutation as well as a genotype-phenotype analysis of the GJB2 and GJB6 genes in 476 samples from non-syndromic unrelated Argentinean deaf patients (104 familial and 372 sporadic cases). Most of them were of prelingual onset (82 %) and 27 % were cochlear implanted. Variation of sequences was detected in 171 of the 474 patients (36 %). Overall, 43 different sequence variations were identified in GJB2 and GJB6. Four of them are reported for the first time in GJB2: c.233dupG, p.Ala78Ser, p.Val190Asp and p.Cys211Tyr. Mutations in GJB6 were detected in 3 % of patients [nine del(GJB6-D13S1830) and three del(GJB6-D13S1854)]. Of the 43 different variations identified in GJB2, 6 were polymorphisms and of the others, 10 (27 %) were truncating and 27 (73 %) were nontruncating. Patients with two truncating mutations had significantly worse hearing impairment than all other groups. Moderate phenotypes were observed in a group of patients carrying biallelic mutations (23 %). This work shows the high prevalence of GJB2 mutations in the Argentinean population and presents an analysis of moderate phenotypes in our cohort.
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Affiliation(s)
- Viviana Dalamón
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular, Dr. Héctor N. Torres (INGEBI) Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Ciudad Autónoma de Buenos Aires, Argentina,
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32
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Chan DK, Chang KW. GJB2-associated hearing loss: Systematic review of worldwide prevalence, genotype, and auditory phenotype. Laryngoscope 2013; 124:E34-53. [DOI: 10.1002/lary.24332] [Citation(s) in RCA: 183] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/10/2013] [Indexed: 12/17/2022]
Affiliation(s)
- Dylan K. Chan
- Department of Otolaryngology-Head and Neck Surgery; University of California; San Francisco U.S.A
| | - Kay W. Chang
- Department of Otolaryngology-Head and Neck Surgery; Stanford University School of Medicine; Stanford California U.S.A
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Cooper DN, Krawczak M, Polychronakos C, Tyler-Smith C, Kehrer-Sawatzki H. Where genotype is not predictive of phenotype: towards an understanding of the molecular basis of reduced penetrance in human inherited disease. Hum Genet 2013; 132:1077-130. [PMID: 23820649 PMCID: PMC3778950 DOI: 10.1007/s00439-013-1331-2] [Citation(s) in RCA: 417] [Impact Index Per Article: 37.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2013] [Accepted: 06/15/2013] [Indexed: 02/06/2023]
Abstract
Some individuals with a particular disease-causing mutation or genotype fail to express most if not all features of the disease in question, a phenomenon that is known as 'reduced (or incomplete) penetrance'. Reduced penetrance is not uncommon; indeed, there are many known examples of 'disease-causing mutations' that fail to cause disease in at least a proportion of the individuals who carry them. Reduced penetrance may therefore explain not only why genetic diseases are occasionally transmitted through unaffected parents, but also why healthy individuals can harbour quite large numbers of potentially disadvantageous variants in their genomes without suffering any obvious ill effects. Reduced penetrance can be a function of the specific mutation(s) involved or of allele dosage. It may also result from differential allelic expression, copy number variation or the modulating influence of additional genetic variants in cis or in trans. The penetrance of some pathogenic genotypes is known to be age- and/or sex-dependent. Variable penetrance may also reflect the action of unlinked modifier genes, epigenetic changes or environmental factors. At least in some cases, complete penetrance appears to require the presence of one or more genetic variants at other loci. In this review, we summarize the evidence for reduced penetrance being a widespread phenomenon in human genetics and explore some of the molecular mechanisms that may help to explain this enigmatic characteristic of human inherited disease.
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Affiliation(s)
- David N. Cooper
- Institute of Medical Genetics, School of Medicine, Cardiff University, Heath Park, Cardiff, CF14 4XN UK
| | - Michael Krawczak
- Institute of Medical Informatics and Statistics, Christian-Albrechts University, 24105 Kiel, Germany
| | | | - Chris Tyler-Smith
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, CB10 1SA UK
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Riahi Z, Chahed H, Jaafoura H, Zainine R, Messaoud O, Naili M, Nagara M, Hammami H, Laroussi N, Bouyacoub Y, Kefi R, Bonnet C, Besbes G, Abdelhak S. A novel frameshift mutation (c.405delC) in the GJB2 gene associated with autosomal recessive hearing loss in two Tunisian families. Int J Pediatr Otorhinolaryngol 2013; 77:1485-8. [PMID: 23856379 DOI: 10.1016/j.ijporl.2013.06.015] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/11/2013] [Revised: 06/17/2013] [Accepted: 06/18/2013] [Indexed: 10/26/2022]
Abstract
OBJECTIVES Mutations in GJB2 are found to be responsible for 50% of congenital autosomal recessive non-syndromic hearing loss, one of the most important mutations in this gene is the c.35delG, which is responsible for the majority of GJB2 related deafness in the Tunisian population. The aim of this study was to determine the molecular etiology of hearing loss in two Tunisian individuals. METHODS We screened two Tunisian individuals affected by congenital, bilateral, profound, sensorineural hearing loss for mutations in GJB2 gene using PCR and direct sequencing. RESULTS We identified a novel frameshift mutation in the GJB2 gene, the c.405delC resulting in a truncated protein (p.Tyr136Thrfs*32). It was found in compound heterozygosity with the c.35delG in two non-consanguineous unrelated families from Tunisia. One patient underwent a cochlear implant at 4 years. Initial evaluations post-implantation indicate a successful cochlear implant outcome since the patient began to acquire language abilities and auditory sensation. CONCLUSIONS With this novel GJB2 mutation, the mutational spectrum of this gene continues to broaden in our population. The occurrence of biallelic GJB2 mutations for the other deaf girl, despite the neonatal pain and hypotension due to complicated delivery, led us to confirm the importance of GJB2 screening for cochlear implant candidates regardless of the etiology of deafness in populations with a relatively high frequency of GJB2 mutation carriers.
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Affiliation(s)
- Zied Riahi
- Laboratoire de Génomique Biomédicale et Oncogénétique, Institut Pasteur de Tunis, BP 74, 13 Place Pasteur, Tunis 1002, Tunisia
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Riahi Z, Hammami H, Ouragini H, Messai H, Zainine R, Bouyacoub Y, Romdhane L, Essaid D, Kefi R, Rhimi M, Bedoui M, Dhaouadi A, Feldmann D, Jonard L, Besbes G, Abdelhak S. Update of the spectrum of GJB2 gene mutations in Tunisian families with autosomal recessive nonsyndromic hearing loss. Gene 2013; 525:1-4. [DOI: 10.1016/j.gene.2013.04.078] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2012] [Revised: 02/20/2013] [Accepted: 04/24/2013] [Indexed: 11/25/2022]
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Usami SI, Nishio SY, Nagano M, Abe S, Yamaguchi T. Simultaneous screening of multiple mutations by invader assay improves molecular diagnosis of hereditary hearing loss: a multicenter study. PLoS One 2012; 7:e31276. [PMID: 22384008 PMCID: PMC3286470 DOI: 10.1371/journal.pone.0031276] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2011] [Accepted: 01/05/2012] [Indexed: 11/18/2022] Open
Abstract
Although etiological studies have shown genetic disorders to be a common cause of congenital/early-onset sensorineural hearing loss, there have been no detailed multicenter studies based on genetic testing. In the present report, 264 Japanese patients with bilateral sensorineural hearing loss from 33 ENT departments nationwide participated. For these patients, we first applied the Invader assay for screening 47 known mutations of 13 known deafness genes, followed by direct sequencing as necessary. A total of 78 (29.5%) subjects had at least one deafness gene mutation. Mutations were more frequently found in the patients with congenital or early-onset hearing loss, i.e., in those with an awareness age of 0-6 years, mutations were significantly higher (41.8%) than in patients with an older age of awareness (16.0%). Among the 13 genes, mutations in GJB2 and SLC26A4 were mainly found in congenital or early-onset patients, in contrast with mitochondrial mutations (12S rRNA m.1555A>G, tRNA(Leu(UUR)) m.3243A>G), which were predominantly found in older-onset patients. The present method of simultaneous screening of multiple deafness mutations by Invader assay followed by direct sequencing will enable us to detect deafness mutations in an efficient and practical manner for clinical use.
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Affiliation(s)
- Shin-ichi Usami
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Asahi, Matsumoto, Japan.
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Keratitis-Ichthyosis-Deafness Syndrome, Atypical Connexin GJB2 Gene Mutation, and Peripheral T-Cell Lymphoma: More Than a Random Association? Case Rep Hematol 2011; 2011:848461. [PMID: 22937313 PMCID: PMC3420635 DOI: 10.1155/2011/848461] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2011] [Accepted: 06/26/2011] [Indexed: 11/17/2022] Open
Abstract
Keratitis-ichthyosis-deafness (KID) syndrome is a rare congenital disorder characterized by skin lesions, neurosensorial hypoacusia, and keratitis, usually due to the c.148G → A mutation involving the connexin 26 gene. We report on a KID patient who showed the atypical c.101T → C mutation and developed a T-cell lymphoma so far never described in this group of patients.
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Dodson KM, Blanton SH, Welch KO, Norris VW, Nuzzo RL, Wegelin JA, Marin RS, Nance WE, Pandya A, Arnos KS. Vestibular dysfunction in DFNB1 deafness. Am J Med Genet A 2011; 155A:993-1000. [PMID: 21465647 DOI: 10.1002/ajmg.a.33828] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2010] [Accepted: 11/01/2010] [Indexed: 11/07/2022]
Abstract
Mutations of GJB2 and GJB6 (connexin-26 and 30) at the DFNB1 locus are the most common cause of autosomal recessive, nonsyndromic deafness. Despite their widespread expression throughout the vestibular system, vestibular dysfunction has not been widely recognized as a commonly associated clinical feature. The observations of vertigo accompanying DFNB1 deafness in several large families prompted our hypothesis that vestibular dysfunction may be an integral, but often overlooked, component of DFNB1 deafness. Our aim was to define the prevalence of vestibular dysfunction in Cases of DFNB1 deafness and Controls with other forms of deafness. We developed and used a survey to assess symptoms of vestibular dysfunction, medical, and family history was distributed to Cases with deafness due to pathogenic GJB2 and/or GJB6 mutations and deaf Controls without DFNB1 deafness. Our results showed: Surveys were returned by 235/515 Cases (46%) with DFNB1 mutations and 121/321 Controls (38%) without these mutations. The mean age of Cases (41) was younger than Controls (51; P < 0.001). Vestibular dysfunction was reported by 127 (54%) of Cases and was present at significantly higher rates in Cases than in deaf Controls without DFNB1 deafness (P < 0.03). Most (63%) had to lie down in order for vertigo to subside, and 48% reported that vertigo interfered with activities of daily living. Vertigo was reported by significantly more Cases with truncating than non-truncating mutations and was also associated with a family history of dizziness. We conclude that vestibular dysfunction appears to be more common in DFNB1 deafness than previously recognized and affects activities of daily living in many patients.
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Affiliation(s)
- Kelley M Dodson
- Department of Otolaryngology, Virginia Commonwealth University, Richmond, USA.
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Yan D, Liu XZ. Modifiers of hearing impairment in humans and mice. Curr Genomics 2010; 11:269-78. [PMID: 21119891 PMCID: PMC2930666 DOI: 10.2174/138920210791233054] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2010] [Revised: 04/03/2010] [Accepted: 04/07/2010] [Indexed: 02/04/2023] Open
Abstract
Lack of penetrance and variability of expression are common findings in nonsyndromic hearing loss with autosomal dominant mode of inheritance, but are also seen with recessive inheritance. Now we know that genotype cannot necessarily predict phenotype due to the complexity of the genome, the proteome interacting with the transcriptome, and the dynamically coupled systems that are involved. The contribution of genetic background to phenotypic diversity reflects the additive and interactive (epistasis) effects of multiple genes. Because, individual genes do not act alone but rather in concert with many other genes, it is not surprising that, modifier genes are common source of phenotypic variation in human populations. They can affect the phenotypic outcome of a given genotype by interacting in the same or in a parallel biological pathway as the disease gene. These modifier genes modulate penetrance, dominance, pleiotropy or expressivity in individuals with Mendelian traits and can also be exerted by influencing the severity, the penetrance, the age of onset and the progression of a disease. In this review, we focus on modifier genes that specifically affect hearing loss phenotypes in humans as well as those described in mice. We also include examples of digenic inheritance of deafness, because additive or interactive effects can also result from interaction between two mutant genes.
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Affiliation(s)
| | - Xue-Zhong Liu
- Department of Otolaryngology, Miller School of Medicine, University of Miami, Miami, FL 33136, USA
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Su CC, Li SY, Su MC, Chen WC, Yang JJ. Mutation R184Q of connexin 26 in hearing loss patients has a dominant-negative effect on connexin 26 and connexin 30. Eur J Hum Genet 2010; 18:1061-4. [PMID: 20442751 DOI: 10.1038/ejhg.2010.50] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Hearing impairment is the most common sensory disorder worldwide. In a recent study, the authors have shown that a heterozygous missense mutation, p.R184Q, in the connexin 26 (Cx26) is causally related to hearing loss. However, the functional change in the Cx26R184Q mutant remains unknown. This study compared the intracellular distribution and assembly of mutant Cx26R184Q with that of the wild-type (WT) Cx26 and Cx30WT in tet-on HeLa cells and the effect that the mutant protein had on those cells. Fluorescent localization assay of WT Cx26 showed the typical punctuate pattern of gap junction channel between neighboring expression cells. Conversely, the p.R184Q missense mutation resulted in accumulation of the Cx26 mutant protein in the Golgi apparatus rather than in the cytoplasmic membrane. Cx26R184Q coexpressed with either Cx26WT or Cx30WT showed perinuclear localization by bidirectional tet-on expression system, suggesting the impairment of the ability of both WT proteins to intracellular trafficking and targeting to the plasma membrane. Therefore, we proposed that Cx26R184Q has a dominant-negative effect on the function of WT Cx26 and Cx30.
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Wilch E, Azaiez H, Fisher RA, Elfenbein J, Murgia A, Birkenhäger R, Bolz H, Da Silva-Costa SM, Del Castillo I, Haaf T, Hoefsloot L, Kremer H, Kubisch C, Le Marechal C, Pandya A, Sartorato EL, Schneider E, Van Camp G, Wuyts W, Smith RJH, Friderici KH. A novel DFNB1 deletion allele supports the existence of a distant cis-regulatory region that controls GJB2 and GJB6 expression. Clin Genet 2010; 78:267-74. [PMID: 20236118 DOI: 10.1111/j.1399-0004.2010.01387.x] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Eleven affected members of a large German-American family segregating recessively inherited, congenital, non-syndromic sensorineural hearing loss (SNHL) were found to be homozygous for the common 35delG mutation of GJB2, the gene encoding the gap junction protein Connexin 26. Surprisingly, four additional family members with bilateral profound SNHL carried only a single 35delG mutation. Previously, we demonstrated reduced expression of both GJB2 and GJB6 mRNA from the allele carried in trans with that bearing the 35delG mutation in these four persons. Using array comparative genome hybridization (array CGH), we have now identified on this allele a deletion of 131.4 kb whose proximal breakpoint lies more than 100 kb upstream of the transcriptional start sites of GJB2 and GJB6. This deletion, del(chr13:19,837,344-19,968,698), segregates as a completely penetrant DFNB1 allele in this family. It is not present in 528 persons with SNHL and monoallelic mutation of GJB2 or GJB6, and we have not identified any other candidate pathogenic copy number variation by arrayCGH in a subset of 10 such persons. Characterization of distant GJB2/GJB6 cis-regulatory regions evidenced by this allele may be required to find the 'missing' DFNB1 mutations that are believed to exist.
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Affiliation(s)
- E Wilch
- Genetics Program, Michigan State University, East Lansing, MI 48824, USA
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Primignani P, Trotta L, Castorina P, Lalatta F, Sironi F, Radaelli C, Degiorgio D, Curcio C, Travi M, Ambrosetti U, Cesarani A, Garavelli L, Formigoni P, Milani D, Murri A, Cuda D, Coviello DA. Analysis of the GJB2 and GJB6 genes in Italian patients with nonsyndromic hearing loss: frequencies, novel mutations, genotypes, and degree of hearing loss. Genet Test Mol Biomarkers 2009; 13:209-17. [PMID: 19371219 DOI: 10.1089/gtmb.2008.0086] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Mutations in the GJB2 gene, which encodes the gap-junction protein connexin 26, are the most common cause of nonsyndromic hearing loss (NSHL) and account for about 32% of cases. We analyzed 734 patients and identified mutations in 474/1468 chromosomes. Thirty-six different mutations and five polymorphisms were found in 269 NSHL subjects. Our data confirm 35delG as the most frequent GJB2 mutation in the Italian population, accounting for about 68% of all the mutated GJB2 alleles analyzed. We also identified two novel variants: the V156I mutation and the C>A change at nucleotide 684 in the 3'UTR of the gene. The GJB6 gene deletion, del(GJB6-D13S1830), which can cause HL in combination with GJB2 mutations in trans, was identified in three patients, while the del(GJB6-D13S1854) was not observed in our cohort of patients. We collected audiometric data from 200 patients with biallelic DFNB1 mutations or with dominant mutation in GJB2 to determine the degree of HL to correlate the genotypes with the audiological phenotypes.
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Affiliation(s)
- Paola Primignani
- Laboratorio di Genetica Medica, Fondazione IRCCS Ospedale Maggiore Policlinico, Mangiagalli e Regina Elena-Milano, Milan, Italy.
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Belguith H, Tlili A, Dhouib H, Ben Rebeh I, Lahmar I, Charfeddine I, Driss N, Ghorbel A, Ayadi H, Masmoudi S. Mutation in gap and tight junctions in patients with non-syndromic hearing loss. Biochem Biophys Res Commun 2009; 385:1-5. [PMID: 19254696 DOI: 10.1016/j.bbrc.2009.02.125] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2009] [Accepted: 02/23/2009] [Indexed: 10/21/2022]
Abstract
Biallelic mutations in the GJB2, GJB3, GJB6 and CLDN14 genes have been implicated in autosomal recessive non-syndromic hearing impairment (ARNSHI). Moreover, a large number of GJB2 heterozygous patients was reported. The phenotype was in partly justified by the occurrence of two deletions including GJB6. We analysed GJB2, GJB6, GJB3 and CLDN14 in 102 Tunisian patients with ARNSHI. The deletions del(GJB6-D13S1830) and del(GJB6-D13S1854) were also screened. The c.35delG in GJB2 was the most frequent mutation (21.57%). It was detected at heterozygous state in 2 patients. The del(GJB6-D13S1830) was identified in one case at heterozygous state. No other mutation in studied gap junction genes was detected in heterozygous patients. Several polymorphisms were identified in GJB3, GJB6 and CLDN14. Our study confirms the importance of GJB2 screening in ARNSHI and suggests that in consanguineous populations, a single DFNB1 mutant allele in individuals with HI is likely due to a coincidental carrier state.
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Affiliation(s)
- Hanen Belguith
- Unité Cibles pour le Diagnostic et la Thérapie, Centre de Biotechnologie de Sfax, Tunisia
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Gürtler N, Egenter C, Bösch N, Plasilova M. Mutation analysis of the Cx26, Cx30, and Cx31 genes in autosomal recessive nonsyndromic hearing impairment. Acta Otolaryngol 2008; 128:1056-62. [PMID: 18607988 DOI: 10.1080/00016480701854727] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
CONCLUSION Biallelic Cx26 mutations are the most common cause of autosomal recessive nonsyndromic hearing impairment (ARNHI) in Switzerland. Mutations in Cx30 and 31, digenic mutations as well as large deletions/duplications, are unlikely to be a major cause of hearing loss in Swiss patients with ARNHI. Multiplex ligation-dependent probe amplification (MLPA) is a highly accurate screening method for detection of c.del(GJB6-D13S1830). OBJECTIVES The intent of this study was to investigate the prevalence of the point and digenic mutations including large deletions and duplications in the Cx26, 30, and 31 genes in a Swiss patient cohort with ARNHI and cochlear implant. PATIENTS AND METHODS The coding regions of Cx26, 30, and 31 were sequenced in 32 patients. Large deletions/duplications were assessed by MLPA. RESULTS In one patient digenic heterozygous mutations involving Cx26 (c.35delG) and Cx30 (c.del(GJB6-D13S1830)) were identified. Biallelic Cx26 mutations were detected in 31%. One putative mutation (c.94C>T) was found in Cx31. MLPA analysis did not reveal any additional deletion or duplication in all three Cx genes, except for the heterozygous c.del(GJB6-D13S1830) deletion.
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Gopalarao D, Kimberling WJ, Jesteadt W, Kelley PM, Beauchaine KL, Cohn ES. Is hearing loss due to mutations in the Connexin 26 gene progressive? Int J Audiol 2008; 47:11-20. [PMID: 18196482 DOI: 10.1080/14992020701602087] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Serial audiograms were analysed for seven subjects, who were homozygous for the 35delG GJB2 mutation. The criterion for determining progression of hearing loss was at least a 1-dB loss in air conduction pure-tone average-3 (ACPTA-3) or ACPTA-4 per year for 2 to 10 years, with a minimum change of 10 dB ACPTA 3 or 4. Bilateral progression of hearing loss was found in 43% (3/7) of the subjects. A meta-analysis of seven studies with non-overlapping data sets and similar ascertainment criteria indicated that 19% of DFNB1 subjects with GJB2 mutations have progressive hearing loss. These data suggest that it may be incorrect to assume that congenital hearing loss due to this mutation is stable. We recommend rigorous audiologic surveillance for individuals with DFNB1.
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Affiliation(s)
- Deepika Gopalarao
- Ali Yavar Jung National Institute for the Hearing Handicapped, New Delhi, India
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47
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Abstract
Hearing impairment is a frequent condition in humans. Identification of the causative genes for the early onset forms of isolated deafness began 15 years ago and has been very fruitful. To date, approximately 50 causative genes have been identified. Yet, limited information regarding the underlying pathogenic mechanisms can be derived from hearing tests in deaf patients. This chapter describes the success of mouse models in the elucidation of some pathophysiological processes in the auditory sensory organ, the cochlea. These models have revealed a variety of defective structures and functions at the origin of deafness genetic forms. This is illustrated by three different examples: (1) the DFNB9 deafness form, a synaptopathy of the cochlear sensory cells where otoferlin is defective; (2) the Usher syndrome, in which deafness is related to abnormal development of the hair bundle, the mechanoreceptive structure of the sensory cells to sound; (3) the DFNB1 deafness form, which is the most common form of inherited deafness in Caucasian populations, mainly caused by connexin-26 defects that alter gap junction communication between nonsensory cochlear cells.
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Affiliation(s)
- Michel Leibovici
- Institut Pasteur, Unite de Genetique et Physiologie de l'Audition, Paris, France
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48
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Abe S, Yamaguchi T, Usami SI. Application of Deafness Diagnostic Screening Panel Based on Deafness Mutation/Gene Database Using Invader Assay. ACTA ACUST UNITED AC 2007; 11:333-40. [DOI: 10.1089/gte.2007.0002] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Affiliation(s)
- Satoko Abe
- Division of Advanced Technology and Development, BML, Inc., Kawagoe-shi, Saitama 350-1101, Japan
| | - Toshikazu Yamaguchi
- Division of Advanced Technology and Development, BML, Inc., Kawagoe-shi, Saitama 350-1101, Japan
| | - Shin-Ichi Usami
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto 390-8621, Japan
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Meyer NC, Nishimura CJ, McMordie S, Smith RJH. Audioprofiling identifiesTECTAandGJB2-related deafness segregating in a single extended pedigree. Clin Genet 2007; 72:130-7. [PMID: 17661817 DOI: 10.1111/j.1399-0004.2007.00828.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
An audioprofile displays phenotypic data from several audiograms on a single graph that share a common genotype. In this report, we describe the application of audioprofiling to a large family in which a genome-wide screen failed to identify a deafness locus. Analysis of audiograms by audioprofiling suggested that two persons with hearing impairment had a different deafness genotype. On this basis, we reassigned affectation status and identified a p.Cys1837Arg autosomal dominant mutation in alpha-tectorin segregating in all family members except two persons, who segregated autosomal recessive deafness caused by p.Val37Ile and p.Leu90Pro mutations in Connexin 26. One nuclear family in the extended pedigree segregates both dominant and recessive non-syndromic hearing loss.
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Affiliation(s)
- N C Meyer
- Department of Otolaryngology, Carver College of Medicine, The University of Iowa, Iowa City, IA 52242, USA
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50
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Apps SA, Rankin WA, Kurmis AP. Connexin 26 mutations in autosomal recessive deafness disorders: a review. Int J Audiol 2007; 46:75-81. [PMID: 17365058 DOI: 10.1080/14992020600582190] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
This review explores the association between GJB2 gene mutations, encoding connexin 26 (Cx26), and nonsyndromic hearing loss. Connexins are proteins that form intracellular membrane channels and regulate ion movement between contiguous fluid spaces. A family of autosomal gene mutations has been identified that lead to abnormal connexin expression within the inner ear that are associated with hearing loss. The exact mechanism by which this link is elicited remains unclear. We aim to highlight the clinically underestimated prevalence of GJB2 gene mutations, to explore the influential role of ethnic diversity in mutation frequency, and to provide a framework for hearing specialists in considering the differential diagnosis of nonsyndromic hearing loss. By linking an observed phenotype associated with abnormal Cx26 expression to the current understanding of the biological and genetic basis underlying it will allow a more accurate clinical description of associated hearing loss, and therefore enable more effective patient management and genetic counselling.
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Affiliation(s)
- Stacey A Apps
- School of Speech Pathology and Audiology, Faculty of Health Sciences, Flinders University, Adelaide, Australia
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