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Shen J, Oza AM, Del Castillo I, Duzkale H, Matsunaga T, Pandya A, Kang HP, Mar-Heyming R, Guha S, Moyer K, Lo C, Kenna M, Alexander JJ, Zhang Y, Hirsch Y, Luo M, Cao Y, Wai Choy K, Cheng YF, Avraham KB, Hu X, Garrido G, Moreno-Pelayo MA, Greinwald J, Zhang K, Zeng Y, Brownstein Z, Basel-Salmon L, Davidov B, Frydman M, Weiden T, Nagan N, Willis A, Hemphill SE, Grant AR, Siegert RK, DiStefano MT, Amr SS, Rehm HL, Abou Tayoun AN. Consensus interpretation of the p.Met34Thr and p.Val37Ile variants in GJB2 by the ClinGen Hearing Loss Expert Panel. Genet Med 2019; 21:2442-2452. [PMID: 31160754 PMCID: PMC7235630 DOI: 10.1038/s41436-019-0535-9] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2018] [Accepted: 04/24/2019] [Indexed: 12/02/2022] Open
Abstract
PURPOSE Pathogenic variants in GJB2 are the most common cause of autosomal recessive sensorineural hearing loss. The classification of c.101T>C/p.Met34Thr and c.109G>A/p.Val37Ile in GJB2 are controversial. Therefore, an expert consensus is required for the interpretation of these two variants. METHODS The ClinGen Hearing Loss Expert Panel collected published data and shared unpublished information from contributing laboratories and clinics regarding the two variants. Functional, computational, allelic, and segregation data were also obtained. Case-control statistical analyses were performed. RESULTS The panel reviewed the synthesized information, and classified the p.Met34Thr and p.Val37Ile variants utilizing professional variant interpretation guidelines and professional judgment. We found that p.Met34Thr and p.Val37Ile are significantly overrepresented in hearing loss patients, compared with population controls. Individuals homozygous or compound heterozygous for p.Met34Thr or p.Val37Ile typically manifest mild to moderate hearing loss. Several other types of evidence also support pathogenic roles for these two variants. CONCLUSION Resolving controversies in variant classification requires coordinated effort among a panel of international multi-institutional experts to share data, standardize classification guidelines, review evidence, and reach a consensus. We concluded that p.Met34Thr and p.Val37Ile variants in GJB2 are pathogenic for autosomal recessive nonsyndromic hearing loss with variable expressivity and incomplete penetrance.
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Affiliation(s)
- Jun Shen
- Department of Pathology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA.
- Harvard Medical School Center for Hereditary Deafness, Boston, MA, USA.
- Laboratory for Molecular Medicine, Partners HealthCare Personalized Medicine, Cambridge, MA, USA.
| | - Andrea M Oza
- Laboratory for Molecular Medicine, Partners HealthCare Personalized Medicine, Cambridge, MA, USA
- Department of Otolaryngology and Communication Enhancement, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Ignacio Del Castillo
- Servicio de Genetica, Hospital Universitario Ramon y Cajal, IRYCIS, Madrid, Spain
- Centro de Investigacion Biomedica en Red de Enfermedades Raras (CIBERER), Madrid, Spain
| | - Hatice Duzkale
- Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
| | - Tatsuo Matsunaga
- Division of Hearing and Balance Research, National Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center, Tokyo, Japan
| | - Arti Pandya
- University of North Carolina, Chapel Hill, NC, USA
| | | | | | - Saurav Guha
- Counsyl, South San Francisco, CA, USA
- New York Genome Center, New York, NY, 10013, USA
| | | | | | - Margaret Kenna
- Harvard Medical School Center for Hereditary Deafness, Boston, MA, USA
- Department of Otolaryngology and Communication Enhancement, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - John J Alexander
- EGL Genetics/Department of Human Genetics, Emory University School of Medicine, Atlanta, GA, USA
- ConsulGene, LLC, Jacksonville, FL, USA
| | - Yan Zhang
- Certer for Medical Genetics, Guangdong Women and Children Hospital, Guangzhou, Guangdong, China
| | - Yoel Hirsch
- Dor Yeshorim, Committee for Prevention of Jewish Genetic Diseases, Brooklyn, NY, USA
| | - Minjie Luo
- The Children's Hospital of Philadelphia, Philadelphia, PA, USA
- The University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
| | - Ye Cao
- Department of Obstetrics and Gynecology, The Chinese University of Hong Kong, Hong Kong, China
| | - Kwong Wai Choy
- Department of Obstetrics and Gynecology, The Chinese University of Hong Kong, Hong Kong, China
| | - Yen-Fu Cheng
- Department of Medical Research, Taipei Veterans General Hospital, Taipei, Taiwan
- Department of Otolaryngology-Head and Neck Surgery, Taipei Veterinary Hospital, Taipei, Taiwan
- School of Medicine, National Yang-Ming University, Taipei, Taiwan
| | - Karen B Avraham
- Raphael Recanati Genetic Institute, Rabin Medical Center-Beilinson Hospital, Petach Tikva, Israel
| | - Xinhua Hu
- Department of Biostatistics, Fairbanks School of Public Health and School of Medicine, Indiana University, Indianapolis, IN, USA
| | - Gema Garrido
- Servicio de Genetica, Hospital Universitario Ramon y Cajal, IRYCIS, Madrid, Spain
- Centro de Investigacion Biomedica en Red de Enfermedades Raras (CIBERER), Madrid, Spain
| | - Miguel A Moreno-Pelayo
- Servicio de Genetica, Hospital Universitario Ramon y Cajal, IRYCIS, Madrid, Spain
- Centro de Investigacion Biomedica en Red de Enfermedades Raras (CIBERER), Madrid, Spain
| | - John Greinwald
- Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
| | - Kejian Zhang
- Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
| | - Yukun Zeng
- Certer for Medical Genetics, Guangdong Women and Children Hospital, Guangzhou, Guangdong, China
| | - Zippora Brownstein
- Raphael Recanati Genetic Institute, Rabin Medical Center-Beilinson Hospital, Petach Tikva, Israel
| | - Lina Basel-Salmon
- Raphael Recanati Genetic Institute, Rabin Medical Center-Beilinson Hospital, Petach Tikva, Israel
- Pediatric Genetics Clinic, Schneider Children's Medical Center of Israel, Petach Tikva, Israel
- Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
- Felsenstein Medical Research Center, Petach Tikva, Israel
| | - Bella Davidov
- Raphael Recanati Genetic Institute, Rabin Medical Center-Beilinson Hospital, Petach Tikva, Israel
| | - Moshe Frydman
- Raphael Recanati Genetic Institute, Rabin Medical Center-Beilinson Hospital, Petach Tikva, Israel
- Danek Gartner Institute of Human Genetics, Sheba Medical Center, Tel Hashomer, Israel
| | - Tzvi Weiden
- Dor Yeshorim, Committee for Prevention of Jewish Genetic Diseases, Jerusalem, Israel
| | - Narasimhan Nagan
- Integrated Genetics, Laboratory Corporation of America® Holdings, Westborough, MA, USA
| | - Alecia Willis
- Integrated Genetics, Laboratory Corporation of America® Holdings, Research Triangle Park, NC, USA
| | - Sarah E Hemphill
- Laboratory for Molecular Medicine, Partners HealthCare Personalized Medicine, Cambridge, MA, USA
| | - Andrew R Grant
- Laboratory for Molecular Medicine, Partners HealthCare Personalized Medicine, Cambridge, MA, USA
- The Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Rebecca K Siegert
- Laboratory for Molecular Medicine, Partners HealthCare Personalized Medicine, Cambridge, MA, USA
- The Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Marina T DiStefano
- Laboratory for Molecular Medicine, Partners HealthCare Personalized Medicine, Cambridge, MA, USA
| | - Sami S Amr
- Department of Pathology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
- Harvard Medical School Center for Hereditary Deafness, Boston, MA, USA
- Laboratory for Molecular Medicine, Partners HealthCare Personalized Medicine, Cambridge, MA, USA
| | - Heidi L Rehm
- Department of Pathology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
- Harvard Medical School Center for Hereditary Deafness, Boston, MA, USA
- Laboratory for Molecular Medicine, Partners HealthCare Personalized Medicine, Cambridge, MA, USA
- The Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA
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Kecskeméti N, Szönyi M, Gáborján A, Küstel M, Milley GM, Süveges A, Illés A, Kékesi A, Tamás L, Molnár MJ, Szirmai Á, Gál A. Analysis of GJB2 mutations and the clinical manifestation in a large Hungarian cohort. Eur Arch Otorhinolaryngol 2018; 275:2441-2448. [PMID: 30094485 DOI: 10.1007/s00405-018-5083-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2018] [Accepted: 07/31/2018] [Indexed: 11/25/2022]
Abstract
PURPOSE Pathogenic variants of the gap junction beta 2 (GJB2) gene are responsible for about 50% of hereditary non-syndromic sensorineural hearing loss (NSHL). In this study, we report mutation frequency and phenotype comparison of different GJB2 gene alterations in Hungarian NSHL patients. METHODS The total coding region of the GJB2 gene was analyzed with Sanger or NGS sequencing for 239 patients with NSHL and 160 controls. RESULTS Homozygous and compound heterozygous GJB2 mutations were associated with early onset serious clinical phenotype in 28 patients. In 24 patients, two deletion or nonsense mutations were detected in individuals with mainly prelingual NSHL. In compound heterozygous cases, a combination of deletion and missense mutations associated with milder postlingual NSHL. A further 25 cases harbored single heterozygous GJB2 mutations mainly associated with later onset, milder clinical phenotype. The most common mutation was the c.35delG deletion, with 12.6% allele frequency. The hearing loss was more severe in the prelingual groups. CONCLUSION The mutation frequency of GJB2 in the investigated cohort is lower than in other European cohorts. The most serious cases were associated with homozygous and compound heterozygous mutations. In our cohort the hearing impairment and age of onset was not altered between in cases with only one heterozygous GJB2 mutation and wild type genotype, which may exclude the possibility of autosomal dominant inheritance. In early onset, severe to profound hearing loss cases, if the GJB2 analysis results in only one heterozygous alteration further next generation sequencing is highly recommended.
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Affiliation(s)
- Nóra Kecskeméti
- Institute of Genomic Medicine and Rare Disorders, Semmelweis University, Tömö utca 25-29, Budapest, 1083, Hungary
- Department of Otorhinolaryngology, Head and Neck Surgery, Semmelweis University, Szigony utca 36, Budapest, 1083, Hungary
| | - Magdolna Szönyi
- Department of Otorhinolaryngology, Head and Neck Surgery, Semmelweis University, Szigony utca 36, Budapest, 1083, Hungary
| | - Anita Gáborján
- Department of Otorhinolaryngology, Head and Neck Surgery, Semmelweis University, Szigony utca 36, Budapest, 1083, Hungary
| | - Marianna Küstel
- Department of Otorhinolaryngology, Head and Neck Surgery, Semmelweis University, Szigony utca 36, Budapest, 1083, Hungary
| | - György Máté Milley
- Institute of Genomic Medicine and Rare Disorders, Semmelweis University, Tömö utca 25-29, Budapest, 1083, Hungary
| | - Anna Süveges
- Institute of Genomic Medicine and Rare Disorders, Semmelweis University, Tömö utca 25-29, Budapest, 1083, Hungary
| | - Anett Illés
- Institute of Genomic Medicine and Rare Disorders, Semmelweis University, Tömö utca 25-29, Budapest, 1083, Hungary
| | - Anna Kékesi
- Institute of Genomic Medicine and Rare Disorders, Semmelweis University, Tömö utca 25-29, Budapest, 1083, Hungary
| | - László Tamás
- Department of Otorhinolaryngology, Head and Neck Surgery, Semmelweis University, Szigony utca 36, Budapest, 1083, Hungary
| | - Mária Judit Molnár
- Institute of Genomic Medicine and Rare Disorders, Semmelweis University, Tömö utca 25-29, Budapest, 1083, Hungary
| | - Ágnes Szirmai
- Department of Otorhinolaryngology, Head and Neck Surgery, Semmelweis University, Szigony utca 36, Budapest, 1083, Hungary
| | - Anikó Gál
- Institute of Genomic Medicine and Rare Disorders, Semmelweis University, Tömö utca 25-29, Budapest, 1083, Hungary.
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Felix F, Ribeiro MG, Tomita S, Zalis MG. Frequency of GJB2 mutations in patients with nonsyndromic hearing loss from an ethnically characterized Brazilian population. Braz J Otorhinolaryngol 2018; 85:92-98. [PMID: 29773520 PMCID: PMC9442831 DOI: 10.1016/j.bjorl.2017.10.013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Revised: 09/25/2017] [Accepted: 10/27/2017] [Indexed: 11/24/2022] Open
Abstract
Introduction In different parts of the world, mutations in the GJB2 gene are associated with nonsyndromic hearing loss, and the homozygous 35delG mutation (p.Gly12Valfs*2) is a major cause of hereditary hearing loss. However, the 35delG mutation is not equally prevalent across ethnicities, making it important to study other mutations, especially in multiethnic countries such as Brazil. Objective This study aimed to identify different mutations in the GJB2 gene in patients with severe to profound nonsyndromic sensorineural hearing loss of putative genetic origin, and who were negative or heterozygote for the 35delG mutation. Methods Observational study that analyzed 100 ethnically characterized Brazilian patients with nonsyndromic severe to profound sensorineural hearing loss, who were negative or heterozygote for the 35delG mutation. GJB2 mutations were detected by DNA-based sequencing in this population. Participants’ ethnicities were identified as Latin European, Non-Latin European, Jewish, Native, Turkish, Afro-American, Asian and Others. Results Sixteen participants were heterozygote for the 35delG mutation; 14 participants, including three 35delG heterozygote's, had nine different alterations in the GJB2 gene. One variant, p.Ser199Glnfs*9, detected in two participants, was previously unreported. Three variants were pathogenic (p.Trp172*, p.Val167Met, and p.Arg75Trp), two were non-pathogenic (p.Val27Ile and p.Ile196Thr), and three variants were indeterminate (p.Met34Thr, p.Arg127Leu, and p.Lys168Arg). Three cases of compound heterozygosity were detected: p.[(Gly12Valfs*2)];[(Trp172*)], p.[(Gly12Valfs*2)](;)[(Met34Thr)], and p.[(Gly12Valfs*2)(;)[(Ser199Glnfs*9)]). Conclusion This study detected previously unclassified variants and one case of previously unreported compound heterozygosity.
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Affiliation(s)
- Felippe Felix
- Universidade Federal do Rio de Janeiro (UFRJ), Hospital Universitário Clementino Fraga Filho (HUCFF), Rio de Janeiro, RJ, Brazil.
| | - Marcia Gonçalves Ribeiro
- Universidade Federal do Rio de Janeiro (UFRJ), Hospital Universitário Clementino Fraga Filho (HUCFF), Rio de Janeiro, RJ, Brazil
| | - Shiro Tomita
- Universidade Federal do Rio de Janeiro (UFRJ), Hospital Universitário Clementino Fraga Filho (HUCFF), Rio de Janeiro, RJ, Brazil
| | - Mariano Gustavo Zalis
- Universidade Federal do Rio de Janeiro (UFRJ), Hospital Universitário Clementino Fraga Filho (HUCFF), Rio de Janeiro, RJ, Brazil
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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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Dória M, Fernandes S, Moura CP. Study of Met34Thr variant in nonsyndromic hearing loss in four Portuguese families. Porto Biomed J 2016; 1:32-35. [PMID: 32258544 DOI: 10.1016/j.pbj.2015.07.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2015] [Accepted: 07/28/2015] [Indexed: 10/21/2022] Open
Abstract
Objective The purpose of this work was to characterize the Met34Thr variant in a group of patients with nonsyndromic hearing loss, in order to establish a genotype-phenotype correlation. Methods 13 cases from 4 unrelated Portuguese families were selected, in which one or more hearing-impaired members had Met34Thr variant. Results Met34Thr variant was identified in 11/13 cases. Two cases have an additional mutation - Val153Ile and 35delG. Hearing loss was mild in 2 patients (Met34Thr/Val153Ile; Met34Thr/Met34Thr), moderate in 3(Met34Thr/WT; Met34Thr/35delG; Met34Thr/Met34Thr), severe in 2 (2 Met34Thr/WT) and profound in 1 (Met34Thr/WT). Three individuals with Met34Thr had normal hearing thresholds. Conclusion The present data corroborate the hypothesis that the Met34Thr variant is associated with mild-to-severe forms of deafness and that this variant seems to segregate with a dominant hearing loss with incomplete penetrance and a variable expression of the phenotype. However, other factors are likely to also have a pathologic effect.
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Affiliation(s)
- Mariana Dória
- Faculty of Medicine, University of Porto, Porto, Portugal
| | - Susana Fernandes
- Department of Human Genetics, Faculty of Medicine, University of Porto/São João Hospital Center, Porto, Portugal.,Institute for Research and Innovation in Health/Instituto de Investigação e Inovação em Saúde, University of Porto, Porto, Portugal
| | - Carla Pinto Moura
- Faculty of Medicine, University of Porto, Porto, Portugal.,Institute for Research and Innovation in Health/Instituto de Investigação e Inovação em Saúde, University of Porto, Porto, Portugal.,Department of Otorhinolaryngology and Department of Human Genetics, São João Hospital Center, Porto, Portugal
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Dória M, Neto AP, Santos AC, Barros H, Fernandes S, Moura CP. Prevalence of 35delG and Met34Thr GJB2 variants in Portuguese samples. Int J Pediatr Otorhinolaryngol 2015; 79:2187-90. [PMID: 26482070 DOI: 10.1016/j.ijporl.2015.09.046] [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: 05/14/2015] [Revised: 09/25/2015] [Accepted: 09/30/2015] [Indexed: 10/22/2022]
Abstract
OBJECTIVE To estimate the prevalence of 35delG and Met34Thr variants in a Portuguese children's community sample and to compare these frequencies with nonsyndromic hearing-loss patients. METHODS 502 children were randomly selected among the 8647 participants of the Portuguese birth cohort Generation XXI, and screened for Met34Thr and 35delG variants in the GJB2 gene. These variants were also studied on 89 index-cases, observed in the Clinic of "Hereditary Hearing-loss" in Saint John's Hospital Center, presenting a mild to profound nonsyndromic hearing-loss. RESULTS Among the 502 children from Generation XXI, 10 were heterozygous for the 35delG variant (95% Confidence Interval 1.03-3.68) and 1 homozygous (95% Confidence Interval 0.01-1.24). Other 10 children presented heterozygosity for the Met34Thr variant (95% Confidence Interval 1.03-3.68). No homozygous for the Met34Thr or compound heterozygotes (35delG/Met34Thr) were found. In the total of 89 nonsyndromic hearing-loss patients, 5 (95% Confidence Interval 2.11-12.8) were heterozygous and 7 (95% Confidence Interval 3.61-15.6) were homozygous for the 35delG variant. The Met34Thr variant was found in 4 patients, 2 heterozygous (95% Confidence Interval 0.13-8.31) and 2 homozygous (95% Confidence Interval 0.13-8.31). CONCLUSION The carrier frequency of 35delG and Met34Thr variants in a Portuguese sample was 1 in 50. Our data suggests that the 35delG mutation has an association with deafness. For the Met34Thr variant, no association was observed. However, Met34Thr seemed to conform to an additive model in hearing-loss.
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Affiliation(s)
- Mariana Dória
- Faculty of Medicine, University of Porto, Alameda Professor Hernâni Monteiro, 4200-319 Porto, Portugal.
| | - Ana Paula Neto
- Department of Human Genetics, Faculty of Medicine, University of Porto, Centro Hospitalar São João, Alameda Professor Hernâni Monteiro, 4200-319 Porto, Portugal; Institute for Research and Innovation in Health/Instituto de Investigação e Inovação em Saúde, University of Porto, Alameda Professor Hernâni Monteiro, 4200-319 Porto, Portugal
| | - Ana Cristina Santos
- Department of Clinical Epidemiology, Predictive Medicine and Public Health, Faculty of Medicine, University of Porto, Alameda Professor Hernâni Monteiro, 4200-319 Porto, Portugal; EPI Unit-Institute of Public Health, University of Porto, Rua das Taipas no. 135, 4050-600 Porto, Portugal
| | - Henrique Barros
- Department of Clinical Epidemiology, Predictive Medicine and Public Health, Faculty of Medicine, University of Porto, Alameda Professor Hernâni Monteiro, 4200-319 Porto, Portugal; EPI Unit-Institute of Public Health, University of Porto, Rua das Taipas no. 135, 4050-600 Porto, Portugal
| | - Susana Fernandes
- Department of Human Genetics, Faculty of Medicine, University of Porto, Centro Hospitalar São João, Alameda Professor Hernâni Monteiro, 4200-319 Porto, Portugal; Institute for Research and Innovation in Health/Instituto de Investigação e Inovação em Saúde, University of Porto, Alameda Professor Hernâni Monteiro, 4200-319 Porto, Portugal
| | - Carla Pinto Moura
- Department of Human Genetics, Faculty of Medicine, University of Porto, Centro Hospitalar São João, Alameda Professor Hernâni Monteiro, 4200-319 Porto, Portugal; Institute for Research and Innovation in Health/Instituto de Investigação e Inovação em Saúde, University of Porto, Alameda Professor Hernâni Monteiro, 4200-319 Porto, Portugal; Department of Otorhinolaryngology, Centro Hospitalar São João, Faculty of Medicine, University of Porto, Alameda Professor Hernâni Monteiro, 4200-319 Porto, Portugal
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The controversial p.Met34Thr variant in GJB2 gene: Two siblings, one genotype, two phenotypes. Int J Pediatr Otorhinolaryngol 2015; 79:1316-9. [PMID: 26117665 DOI: 10.1016/j.ijporl.2015.05.041] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/08/2015] [Revised: 05/27/2015] [Accepted: 05/31/2015] [Indexed: 01/02/2023]
Abstract
INTRODUCTION Recent advances in molecular genetics have increased the identification of genes and mutations responsible for inherited forms of hearing loss (HL), enabling early detection of these cases. Approximately, 60% of early-onset HL cases are due to genetic causes, of which 70% are non-syndromic. Of these, 75-80% are inherited in an autosomal recessive pattern (DFNB). Mutations in GJB2 gene, coding for connexin 26 (Cx26), are the major cause of autosomal recessive hereditary HL, but some GJB2 mutations are yet of unclear or controversial significance. OBJECTIVES The aim of the present study was to identify the etiology of hearing loss, and correlate genotype-phenotype, in two Portuguese siblings with profound and moderate non-syndromic sensorineural bilateral HL. MATERIAL AND METHODS The affected subjects and their parents underwent audiological and genetic study. Molecular analysis of GJB2 gene was performed, searching for mutations in the coding region and receptor splicing site by automated sequencing. RESULTS The onset and the degree of HL were different in the two affected subjects. However, the same GJB2 genotype [p.Met34Thr]+[p.Arg184Pro] was identified in both siblings. The c.551G>C (p.Arg184Pro) and c.101T>C (p.Met34Thr) missense variants were inherited from the father and mother, respectively, both heterozygous carriers of these variants. CONCLUSION The clinical and genetic data here presented suggest that the non-syndromic sensorineural HL of these two Portuguese siblings might be due to the presence of p.Met34Thr and p.Arg184Pro variants in compound heterozygosity. If so, p.Met34Thr variant could have function as a hypomorphic allele that may cause HL depending on the opposing GJB2 allele. The observed phenotypic variability may not, however, be solely explained by variable expression of this genotype. A putative modifier gene or mutations in another HL-associated gene could probably be contributing to the severe HL in one of the siblings.
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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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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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Zonta F, Buratto D, Cassini C, Bortolozzi M, Mammano F. Molecular dynamics simulations highlight structural and functional alterations in deafness-related M34T mutation of connexin 26. Front Physiol 2014; 5:85. [PMID: 24624091 PMCID: PMC3941013 DOI: 10.3389/fphys.2014.00085] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2013] [Accepted: 02/12/2014] [Indexed: 11/22/2022] Open
Abstract
Mutations of the GJB2 gene encoding the connexin 26 (Cx26) gap junction protein, which is widely expressed in the inner ear, are the primary cause of hereditary non-syndromic hearing loss in several populations. The deafness–associated single amino acid substitution of methionine 34 (M34) in the first transmembrane helix (TM1) with a threonine (T) ensues in the production of mutant Cx26M34T channels that are correctly synthesized and assembled in the plasma membrane. However, mutant channels overexpressed in HeLa cells retain only 11% of the wild type unitary conductance. Here we extend and rationalize those findings by comparing wild type Cx26 (Cx26WT) and Cx26M34T mutant channels in silico, using molecular dynamics simulations. Our results indicate that the quaternary structure of the Cx26M34T hemichannel is altered at the level of the pore funnel due to the disruption of the hydrophobic interaction between M34 and tryptophan 3 (W3) in the N–terminal helix (NTH). Our simulations also show that external force stimuli applied to the NTHs can detach them from the inner wall of the pore more readily in the mutant than in the wild type hemichannel. These structural alterations significantly increase the free energy barrier encountered by permeating ions, correspondingly decreasing the unitary conductance of the Cx26M34T hemichannel. Our results accord with the proposal that the mutant resides most of the time in a low conductance state. However, the small displacement of the NTHs in our Cx26M34T hemichannel model is not compatible with the formation of a pore plug as in the related Cx26M34A mutant.
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Affiliation(s)
- Francesco Zonta
- Dipartimento di Fisica e Astronomia "G. Galilei", Università degli Studi di Padova Padova, Italy
| | - Damiano Buratto
- Dipartimento di Fisica e Astronomia "G. Galilei", Università degli Studi di Padova Padova, Italy
| | - Chiara Cassini
- Dipartimento di Fisica e Astronomia "G. Galilei", Università degli Studi di Padova Padova, Italy
| | - Mario Bortolozzi
- Dipartimento di Fisica e Astronomia "G. Galilei", Università degli Studi di Padova Padova, Italy ; Istituto Veneto di Medicina Molecolare, Fondazione per la Ricerca Biomedica Avanzata Padova, Italy
| | - Fabio Mammano
- Dipartimento di Fisica e Astronomia "G. Galilei", Università degli Studi di Padova Padova, Italy ; Istituto Veneto di Medicina Molecolare, Fondazione per la Ricerca Biomedica Avanzata Padova, Italy ; Istituto di Neuroscienze, Consiglio Nazionale delle Ricerche Padova, Italy
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11
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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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12
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Martins FTA, Ramos PZ, Svidnicki MCCM, Castilho AM, Sartorato EL. Optimization of simultaneous screening of the main mutations involved in non-syndromic deafness using the TaqMan® OpenArray™ Genotyping platform. BMC MEDICAL GENETICS 2013; 14:112. [PMID: 24156272 PMCID: PMC4015212 DOI: 10.1186/1471-2350-14-112] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/31/2013] [Accepted: 10/14/2013] [Indexed: 11/23/2022]
Abstract
Background Hearing loss is the most common sensory deficit in humans, affecting approximately 10% of the global population. In developed countries, one in every 500 individuals suffers from severe to profound bilateral sensorineural hearing loss. For those up to 5 years old, the proportion is higher, at 2.7 in 1000 individuals, and for adolescents the average is 3.5 in 1000. Among the causes of hearing loss, more than 50% are related to genetic factors. To date, nearly 150 loci and 64 genes have been associated with hearing loss. Mutations in the GJB2 gene, which encodes connexin 26, constitute the main genetic cause. So far, more than 300 variations have been described in this gene. As a response to the clinical and genetic heterogeneity of hearing loss and the importance of correct molecular diagnosis of individuals with hereditary hearing loss, this study worked in the optimization for a diagnostic protocol employing a high-throughput genotyping technology. Methods For this work, was used the TaqMan® OpenArray™ Genotyping platform. This is a high performance, high-throughput technology based on real-time PCR, which enables the evaluation of up to 3072 SNPs (Single Nucleotide Polymorphisms), point mutations, small deletions, and insertions, using a single genotyping plate. For the study, were selected the layout allowing to analyze 32 alterations in 96 individuals simultaneously. In the end, the generated results were validated by conventional techniques, as direct sequencing, Multiplex PCR and RFLP-PCR. Results A total of 376 individuals were analyzed, of which 94 were healthy controls, totaling 4 plates in duplicate. All 31 of the changes analyzed were present in the nuclear genes GJB2, GJB6, CRYL1, TMC1, SLC26A4, miR-96, and OTOF, and in the mitochondrial genes MT-RNR1 and MT-TS1. The reactions were subsequently validated by established techniques (direct sequencing, multiplex PCR, and RFLP-PCR) that had previously been used to perform molecular screening of hearing loss at the Human Genetics Laboratory of the Center for Molecular Biology and Genetic Engineering (CBMEG), at the State University of Campinas (UNICAMP). In total, 11,656 genotyping reactions were performed. Of these, only 351 reactions failed, representing approximately 3.01% of the total. The average accuracy of genotyping using the OpenArray™ plates was 96.99%. Conclusions The results demonstrated the accuracy, low cost, and good reproducibility of the technique, indicating that the TaqMan® OpenArray™ Genotyping Platform is a useful and reliable tool for application in molecular diagnostic testing of hearing loss.
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Affiliation(s)
- Fábio Tadeu Arrojo Martins
- Human Molecular Genetics Laboratory, Center for Molecular Biology and Genetic Engineering (CBMEG), State University of Campinas - UNICAMP, Campinas, SP, Brazil.
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13
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Matos TD, Simões-Teixeira H, Caria H, Gonçalves AC, Chora J, Correia MDC, Moura C, Rosa H, Monteiro L, O'Neill A, Dias Ó, Andrea M, Fialho G. Spectrum and frequency of GJB2 mutations in a cohort of 264 Portuguese nonsyndromic sensorineural hearing loss patients. Int J Audiol 2013; 52:466-71. [PMID: 23668481 DOI: 10.3109/14992027.2013.783719] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
OBJECTIVE To assess the spectrum and prevalence of mutations in the GJB2 gene in Portuguese nonsyndromic sensorineural hearing loss (NSSHL) patients. DESIGN Sequencing of the coding region, basal promoter, exon 1, and donor splice site of the GJB2 gene; screening for the presence of the two common GJB6 deletions. STUDY SAMPLE A cohort of 264 Portuguese NSSHL patients. RESULTS At least one out of 21 different GJB2 variants was identified in 80 (30.2%) of the 264 patients analysed. Two mutant alleles were found in 53 (20%) of these probands, of which 83% (44/53) harboured at least one c.35delG allele. Twenty-seven (10.2%) of the probands harboured only one mutant allele. Subsequent analysis revealed that the GJB6 deletion del(GJB6-D13S1854) was present in at least 7.4% (2/27) of the patients carrying only one mutant GJB2 allele. Overall, one in five (55/264) of the patients were diagnosed as having DFNB1-related NSSHL, of which the vast majority (53/55) harboured only GJB2 mutations. CONCLUSIONS This study provides clear demonstration that mutations in the GJB2 gene are an important cause of NSSHL in Portugal, thus representing a valuable indicator as regards therapeutical and rehabilitation options, as well as genetic counseling of these patients and their families.
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Affiliation(s)
- Tiago Daniel Matos
- Centre for Biodiversity, Functional, and Integrative Genomics BioFIG, Faculty of Science, University of Lisbon, Lisboa, Portugal
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14
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Castro LSSD, Marinho ANDR, Rodrigues EMR, Marques GCT, Carvalho TAAD, Silva LCSD, dos Santos SEB. A study of GJB2 and delGJB6-D13S1830 mutations in Brazilian non-syndromic deaf children from the Amazon region. Braz J Otorhinolaryngol 2013; 79:95-9. [PMID: 23503914 PMCID: PMC9450865 DOI: 10.5935/1808-8694.20130016] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2012] [Accepted: 11/02/2012] [Indexed: 12/12/2022] Open
Abstract
Objective Method Results Conclusion
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15
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Löppönen T, Dietz A, Väisänen ML, Valtonen H, Kosunen A, Hyvärinen A, Ignatius J, Löppönen H. Homozygous M34T mutation of the GJB2 gene associates with an autosomal recessive nonsyndromic sensorineural hearing impairment in Finnish families. Acta Otolaryngol 2012; 132:862-73. [PMID: 22668073 DOI: 10.3109/00016489.2012.669498] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
CONCLUSION The genetic and audiological data support the hypothesis that the p.M34T is a pathogenic mutation in the Finnish population. The p.M34T mutation displays an autosomal recessive pattern of inheritance and is associated with mild to moderate nonsyndromic sensorineural hearing impairment (SNHI) in the homozygous state. The audiograms often display a hearing impairment notch at 2-4 kHz in young patients, which may aid in the early diagnosis. OBJECTIVES The aim of the study was to assess whether the p.M34T mutation in the GJB2 gene may associate with nonsyndromic SNHI. METHODS We systematically reviewed the families with children diagnosed with nonsyndromic SNHI caused by a homozygous p.M34T mutation at the Kuopio and Oulu University Hospital Clinics. The children were re-examined and audiological and genetic data were obtained from their parents and healthy siblings to study genotype-phenotype correlation. RESULTS We describe 11 patients from 6 families including 5 sibling pairs from 6 to 23 years of age with homozygous p.M34T genotype all having mild nonsyndromic SNHI. In addition, we found three patients with compound p.M34T mutation also exhibiting mild to moderate SNHI.
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Affiliation(s)
- Tuija Löppönen
- Department of Paediatrics, Child Neurology, Kuopio University Hospital, Finland
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16
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Minárik G, Tretinárová D, Szemes T, Kádasi L. Prevalence of DFNB1 mutations in Slovak patients with non-syndromic hearing loss. Int J Pediatr Otorhinolaryngol 2012; 76:400-3. [PMID: 22281373 DOI: 10.1016/j.ijporl.2011.12.020] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/24/2011] [Accepted: 12/20/2011] [Indexed: 11/24/2022]
Abstract
OBJECTIVES Non-syndromic hearing loss is one of the most common genetically determined diseases in human. The incidence is approximately 1:700 and most of the cases are caused by mutations in specific locus - DFNB1, which contains two genes -GJB2 and GJB6. For the GJB2 gene following mutations are most prevalent in specific populations - 35delG, 235delC, W24X and 167delT for Caucasians, Asians, Indians and Ashkenazi Jews, respectively. Large deletions are common in GJB6 gene. Many other mutations and polymorphisms were found in DFNB1 focused non-syndromic hearing loss studies thus the establishment of optimal screening protocol should be based on population specific mutation screening studies and is an objective in our study. PATIENTS AND METHODS In our study samples from 273 non-syndromic hearing loss patients were screened for mutations in coding and non-coding part of GJB2 gene and large deletion in GJB6 gene - del(GJB6-D13S1830). RESULTS Causal mutation on both chromosomes was detected in 24.57% of patients, another 9.9% carried causal mutation on one chromosome. Totally 7 polymorphisms: V27I, M34T, F83L, 354 C→T, R127H, V153I, 684 C→A and 11 causal mutations: IVS1+1 G→A, 35delG, W24X, V37I, E47X, 167delT, V84M, L90P, 310del14, 333-334delAA, R184Q were detected. No patient carried the GJB6 deletion mutation (del(GJB6-D13S1830)). CONCLUSION According to our results sequencing of GJB2 coding regions and IVS1+1G→A specific detection should explain approximately 25% of sporadic NSHL cases and these two tests are relevant for use as routine screening protocol for NSHL in Slovakia. The GJB6 del(GJB6-D13S1830) mutation was not detected in any of NSHL samples therefore it is not necessary to implement it in our routine screening protocol.
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Affiliation(s)
- Gabriel Minárik
- Institute of Molecular Biomedicine, Comenius University Faculty of Medicine, Bratislava, Slovakia.
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Hall A, Pembrey M, Lutman M, Steer C, Bitner-Glindzicz M. Prevalence and audiological features in carriers of GJB2 mutations, c.35delG and c.101T>C (p.M34T), in a UK population study. BMJ Open 2012; 2:bmjopen-2012-001238. [PMID: 22855627 PMCID: PMC3449272 DOI: 10.1136/bmjopen-2012-001238] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
OBJECTIVES To determine the carrier rate of the GJB2 mutation c.35delG and c.101T>C in a UK population study; to determine whether carriers of the mutation had worse hearing or otoacoustic emissions compared to non-carriers. DESIGN Prospective cohort study. SETTING University of Bristol, UK. PARTICIPANTS Children in the Avon Longitudinal Study of Parents and Children. 9202 were successfully genotyped for the c.35delG mutation and c.101>T and classified as either carriers or non-carriers. OUTCOME MEASURES Hearing thresholds at age 7, 9 and 11 years and otoacoustic emissions at age 9 and 11. RESULTS The carrier frequency of the c.35delG mutation was 1.36% (95% CI 1.13 to 1.62) and c.101T>C was 2.69% (95% CI 2.37 to 3.05). Carriers of c.35delG and c.101T>C had worse hearing than non-carriers at the extra-high frequency of 16 kHz. The mean difference in hearing at age 7 for the c.35delG mutation was 8.53 dB (95% CI 2.99, 14.07) and 12.57 dB at age 9 (95% CI 8.10, 17.04). The mean difference for c.101T>C at age 7 was 3.25 dB (95% CI -0.25 to 6.75) and 7.61 dB (95% CI 4.26 to 10.96) at age 9. Otoacoustic emissions were smaller in the c.35delG mutation carrier group: at 4 kHz the mean difference was -4.95 dB (95% CI -6.70 to -3.21) at age 9 and -3.94 dB (95% CI -5.78 to -2.10) at age 11. There was weak evidence for differences in otoacoustic emissions amplitude for c.101T>C carriers. CONCLUSION Carriers of the c.35delG mutation and c.101T>C have worse extra-high-frequency hearing than non-carriers. This may be a predictor for changes in lower-frequency hearing in adulthood. The milder effects observed in carriers of c.101T>C are in keeping with its classification as a mutation causing mild/moderate hearing loss in homozygosity or compound heterozygosity.
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Affiliation(s)
- Amanda Hall
- Centre for Hearing and Balance Studies, University of Bristol, Bristol, UK
| | - Marcus Pembrey
- Department of Social and Community Medicine, University of Bristol, Bristol, UK
| | - Mark Lutman
- Institute of Sound and Vibration Research, University of Southampton, Southampton, UK
| | - Colin Steer
- Department of Social and Community Medicine, University of Bristol, Bristol, UK
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Chinetti V, Iossa S, Auletta G, Corvino V, De Luca M, De Falco F, Giannini P, Lilli G, Malesci R, Riccardi P, Marciano E, Franzè A. Mutational analysis forGJB2, GJB6, andGJB3genes in Campania within a universal neonatal hearing screening programme. Int J Audiol 2011; 50:866-70. [DOI: 10.3109/14992027.2011.603757] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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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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Choi SY, Lee KY, Kim HJ, Kim HK, Chang Q, Park HJ, Jeon CJ, Lin X, Bok J, Kim UK. Functional evaluation of GJB2 variants in nonsyndromic hearing loss. Mol Med 2011; 17:550-6. [PMID: 21298213 DOI: 10.2119/molmed.2010.00183] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2010] [Accepted: 01/07/2011] [Indexed: 11/06/2022] Open
Abstract
Mutations in the gap junction β2 (GJB2) gene, encoding the connexin26 (CX26) protein, are the most common cause of non-syndromic hearing loss (HL) in many populations. In the East Asian population, two variants, p.V27I (c.79G>A) and p.E114G (c.341G>A), are considered benign polymorphisms since these variants have been identified in both HL patients and normal hearing controls. However, some studies have postulated that homozygotes carrying both p.V27I and p.E114G variants could cause HL. To elucidate possible roles of these variants, we used in vitro approaches to directly assess the pathogenicity of four haplotypes generated by the two polymorphisms: VE (wild type), I*E (p.V27I variant only), VG* (p.E114G variant only), I*G* (both variants). In biochemical coupling assays, the gap junctions (GJs) composed of VG* and I*G* types displayed defective channel activities compared with those of VE wild types or I*E types, which showed normal channel activities. Interestingly, the defect in hemichannel activity was a bit less severe in I*G* type than VG* type, suggesting that I* variant (p.V27I) may compensate for the deleterious effect of G* variant (p.E114G) in hemichannel activities. Our population studies using 412 Korean individuals showed that I*G* type was detected at around 20% in both HL patients and normal controls, suggesting that I*G* type may not be a pathogenic polymorphism. In contrast, VG* type was very rare (3/824) and detected only in HL patients, suggesting that VG* homozygotes (VG*/VG*) or compound heterozygotes carrying VG* type with other mutations may cause HL.
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Affiliation(s)
- Soo-Young Choi
- Department of Biology, College of Natural Sciences, Kyungpook National University, Daegu, Korea
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Teek R, Kruustük K, Zordania R, Joost K, Reimand T, Möls T, Oitmaa E, Kahre T, Tõnisson N, Ounap K. Prevalence of c.35delG and p.M34T mutations in the GJB2 gene in Estonia. Int J Pediatr Otorhinolaryngol 2010; 74:1007-12. [PMID: 20708129 DOI: 10.1016/j.ijporl.2010.05.026] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/19/2010] [Revised: 05/18/2010] [Accepted: 05/23/2010] [Indexed: 10/19/2022]
Abstract
OBJECTIVE The purpose of this study was to determine the prevalence of c.35delG and p.M34T mutations in the GJB2 gene among children with early onset hearing loss and within a general population of Estonia. METHODS Using an arrayed primer extension assay, we screened 233 probands with early childhood onset hearing loss for 107 different mutations in the GJB2 gene. We then looked for the two most common mutations, c.35delG and p.M34T, in a population of 998 consecutively born Estonian neonates to determine the frequency of these mutations in the general population. RESULTS In 115 (49%) of the patients with early onset hearing loss, we found a mutation in at least one allele of the GJB2 gene. Seventy-three (31%) were homozygous for the c.35delG mutation, seven (3%) were homozygous for the p.M34T mutation, and five (2%) had c35delG/p.M34T compound heterozygosity. Other six identified mutations in GJB2 gene occurred rarely. Among the 998 anonymous newborn samples, we detected 45 who were heterozygous for c.35delG, 2 individuals homozygous for c.35delG, and 58 who were heterozygous for p.M34T. Additionally, we detected two c.35delG/p.M34T compound heterozygotes. CONCLUSION The most common GJB2 gene mutations in Estonian children with early onset hearing loss were c.35delG and p.M34T, with c.35delG accounting for 75% of GJB2 alleles. The carrier frequency for c.35delG and p.M34T in a general population of Estonia was 1 in 22 and 1 in 17, respectively, and was higher than in most other countries.
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Affiliation(s)
- Rita Teek
- Department of Genetics, United Laboratories, Tartu University Hospital, Tartu, Estonia
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Sequence Variations and Haplotypes of the GJB2 Gene Revealed by Resequencing of 192 Chromosomes from the General Population in Korea. Clin Exp Otorhinolaryngol 2010; 3:65-9. [PMID: 20607074 PMCID: PMC2896735 DOI: 10.3342/ceo.2010.3.2.65] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2010] [Accepted: 05/04/2010] [Indexed: 11/08/2022] Open
Abstract
Objectives Hearing impairment (HI) is the most common sensory deficit in human. The Gap Junction Protein, Beta-2 (GJB2) gene encodes the protein connexin 26, and this gene accounts for up to half of the cases of autosomal recessive nonsyndromic HI. This study was conducted to obtain a set of sequence variations (SVs) of the GJB2 gene among Koreans from the general population for making molecular genetic diagnoses and performing genetic counseling. Methods We resequenced the GJB2 gene in 192 chromosomes from 96 adult individuals of Korean descent and who were without a history of hearing difficulty. The data of the SVs was obtained and the haplotypes were reconstructed from the data. Results Five SVs were observed, including a novel one (c.558G>A; p.T186T), with the allele frequencies ranging from 0.5% (1/192) to 41% (79/192). The linkage disequilibrium study and haplotype construction showed that some of the SVs are in tight linkage, resulting in a limited number of haplotypes. Conclusion We observed SVs of the GJB2 gene with different allele frequencies, and a limited number of haplotypes were constructed. The data from this study can be used as reference data for GJB2-related hearing genetic studies, including studies on the founder effect and population genetics, and this data is particularly relevant to people of East Asian decent.
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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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Chinetti V, Iossa S, Auletta G, Laria C, de Luca M, Di Leva F, Riccardi P, Giannini P, Gasparini P, Ciccodicola A, Marciano E, Franzè A. Screening forGJB2andGJB6gene mutations in patients from Campania region with sensorineural hearing loss. Int J Audiol 2010; 49:326-31. [DOI: 10.3109/14992021003601756] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Yilmaz A, Menevse S, Bayazit Y, Karamert R, Ergin V, Menevse A. Two Novel Missense Mutations in the Connexin 26 Gene in Turkish Patients with Nonsyndromic Hearing Loss. Biochem Genet 2009; 48:248-56. [DOI: 10.1007/s10528-009-9314-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2008] [Accepted: 08/21/2009] [Indexed: 11/28/2022]
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Dietz A, Löppönen T, Valtonen H, Hyvärinen A, Löppönen H. Prevalence and etiology of congenital or early acquired hearing impairment in Eastern Finland. Int J Pediatr Otorhinolaryngol 2009; 73:1353-7. [PMID: 19616857 DOI: 10.1016/j.ijporl.2009.06.009] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/17/2009] [Revised: 06/17/2009] [Accepted: 06/18/2009] [Indexed: 10/20/2022]
Abstract
OBJECTIVE The purpose of this study was to determine the prevalence and etiology of congenital or early acquired bilateral sensorineural hearing impairment (SNHI) in children born from 1988 to 2002 in the district of Kuopio University Hospital, Finland, and to compare the results with those from an earlier 14-year period in the same region and similar population. METHODS The data were collected retrospectively from Hospital Records. The degree of hearing impairment was based on average air conduction threshold calculated over the frequencies 0.5, 1, 2 and 4 kHz in the better hearing ear. Hearing impairment was classified as mild (≥ 20-39 dB), moderate (40-69 dB), severe (70-95 dB) and profound (>95 dB). RESULTS We identified 92 children with bilateral SNHI diagnosed before the age of 7 years. The overall prevalence and the prevalence for at least moderate SNHI was 2.1 per 1000 live births and 1.2 per 1000 live births, respectively. We found no differences in the prevalence of SNHI during both study periods. Etiology was genetic in 46%, acquired in 14% and unknown in 40%. Out of the genetic cases 74% were non-syndromic and 26% were syndromic. In comparison to the previous study there was a decline in the proportion of acquired SNHI and the proportion of genetic and unknown cause had increased. Six children in five families had homozygous 35delG mutation and six children in four families presented with a homozygous M34T mutation. CONCLUSIONS The prevalence of congenital or early acquired SNHI in the Kuopio University Hospital district area has not changed during a period of 29 years. Despite possibility to test the GBJ2 gene, the proportion of hearing impairment of unknown etiology remained high.
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Affiliation(s)
- Aarno Dietz
- Department of Otorhinolaryngology, Kuopio University Hospital, PO Box 1777, FIN-70211 Kuopio, Finland.
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Carlsson PI, Fransen E, Stenberg E, Bondeson ML. The influence of genetic factors, smoking and cardiovascular diseases on human noise susceptibility. ACTA ACUST UNITED AC 2009. [DOI: 10.1080/16513860701194683] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Rehm HL. Molecular diagnosis of hearing loss. ACTA ACUST UNITED AC 2008; Chapter 9:Unit9.16. [PMID: 18428366 DOI: 10.1002/0471142905.hg0916s43] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
This unit discusses an approach to identifying a genetic cause in an individual with nonsyndromic hearing loss. Two protocols are presented, including a full-gene sequencing assay to identify mutations in the GJB2 gene encoding the connexin 26 protein. Mutations in the GJB2 gene represent the most common cause of congenital hearing loss. In addition, a protocol to detect the presence of a 342-kb deletion that includes a portion of the GJB6 gene is presented. The GJB6-D13S1830 deletion, in homozygosity or in combination with a single GJB2 mutation, causes hearing loss. In addition to the two protocols presented, the Strategic Planning section presents a discussion of a decision-making process that can be used to begin determining which gene(s) to test for in a patient presenting with nonsyndromic hearing loss. This task can be quite challenging, with the suspected involvement of over 90 genes.
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Affiliation(s)
- Heidi L Rehm
- Laboratory for Molecular Medicine, Harvard-Partners Genome Center, Cambridge, Massachusetts, USA
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29
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Correlation between GJB2 mutations and audiological deficits: personal experience. Eur Arch Otorhinolaryngol 2008; 266:489-94. [DOI: 10.1007/s00405-008-0775-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2008] [Accepted: 07/16/2008] [Indexed: 10/21/2022]
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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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Tang HY, Fang P, Ward PA, Schmitt E, Darilek S, Manolidis S, Oghalai JS, Roa BB, Alford RL. DNA sequence analysis of GJB2, encoding connexin 26: observations from a population of hearing impaired cases and variable carrier rates, complex genotypes, and ethnic stratification of alleles among controls. Am J Med Genet A 2007; 140:2401-15. [PMID: 17041943 PMCID: PMC3623690 DOI: 10.1002/ajmg.a.31525] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Mutations in GJB2 are associated with hereditary hearing loss. DNA sequencing of GJB2 in a cohort of hearing impaired patients and a multi-ethnic control group is reported. Among 610 hearing impaired cases, 43 DNA sequence variations were identified in the coding region of GJB2 including 24 mutations, 8 polymorphisms, 3 unclassified variants (G4D, R127C, M163V), 1 controversial variant (V37I), and 7 novel variants (G12C, N14D, V63A, T86M, L132V, D159, 592_600delinsCAGTGTTCATGACATTC). Sixteen non-coding sequence variations were also identified among cases including the IVS1+1A>G mutation, 2 polymorphisms, and 13 novel variants. A diagnosis of GJB2-associated hearing loss was confirmed for 63 cases (10.3%). Heterozygous mutations were found in 39 cases (6.4%). Eleven cases carrying novel or unclassified variants (1.8 %) and 18 cases carrying the controversial V37I variant were identified (3%). In addition, 294 control subjects from 4 ethnic groups were sequenced for GJB2. Thirteen sequence variations in the coding region of GJB2 were identified among controls including 2 mutations, 6 polymorphisms, 2 unclassified variants (G4D, T123N), 1 controversial variant (V37I), and 2 novel variants (R127L, V207L). Nine sequence variations were identified among controls in the non-coding regions in and around GJB2 exon 2. Of particular interest among controls were the variability in carrier rates and ethnic stratification of alleles, and the complex genotypes among Asians, 47% of whom carried two to four sequence variations in the coding region of GJB2. These data provide new information about carrier rates for GJB2-based hearing loss in various ethnic groups and contribute to evaluation of the pathogenicity of the controversial V37I variant.
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Affiliation(s)
- Hsiao-Yuan Tang
- Bobby R. Alford Department of Otolaryngology—Head and Neck Surgery, Baylor College of Medicine, Houston, Texas
| | - Ping Fang
- Medical Genetics Laboratories, Baylor College of Medicine, Houston, Texas
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas
| | - Patricia A. Ward
- Medical Genetics Laboratories, Baylor College of Medicine, Houston, Texas
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas
| | - Eric Schmitt
- Medical Genetics Laboratories, Baylor College of Medicine, Houston, Texas
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas
| | - Sandra Darilek
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas
| | - Spiros Manolidis
- Department of Otolaryngology—Head and Neck Surgery, Columbia University, New York, New York
| | - John S. Oghalai
- Bobby R. Alford Department of Otolaryngology—Head and Neck Surgery, Baylor College of Medicine, Houston, Texas
| | - Benjamin B. Roa
- Medical Genetics Laboratories, Baylor College of Medicine, Houston, Texas
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas
| | - Raye Lynn Alford
- Bobby R. Alford Department of Otolaryngology—Head and Neck Surgery, Baylor College of Medicine, Houston, Texas
- Correspondence to: Raye Lynn Alford, Ph.D., F.A.C.M.G., Bobby R. Alford Department of Otolaryngology—Head and Neck Surgery, Baylor College of Medicine, One Baylor Plaza, NA102, Houston 77030, TX.
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Pollak A, Skórka A, Mueller-Malesińska M, Kostrzewa G, Kisiel B, Waligóra J, Krajewski P, Ołdak M, Korniszewski L, Skarżyński H, Ploski R. M34T and V37I mutations inGJB2 associated hearing impairment: Evidence for pathogenicity and reduced penetrance. Am J Med Genet A 2007; 143A:2534-43. [DOI: 10.1002/ajmg.a.31982] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Dahl HHM, Tobin SE, Poulakis Z, Rickards FW, Xu X, Gillam L, Williams J, Saunders K, Cone-Wesson B, Wake M. The contribution of GJB2 mutations to slight or mild hearing loss in Australian elementary school children. J Med Genet 2006; 43:850-5. [PMID: 16840571 PMCID: PMC2563186 DOI: 10.1136/jmg.2006.042051] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2006] [Revised: 06/01/2006] [Accepted: 06/14/2006] [Indexed: 12/15/2022]
Abstract
BACKGROUND There is a lack of information on prevalence, cause and consequences of slight/mild bilateral sensorineural hearing loss (SNHL) in children. We report the first systematic genetic analysis of the GJB2 gene in a population-derived sample of children with slight/mild bilateral SNHL. METHODS Hearing tests were conducted in 6240 Australian elementary school children in Grades 1 and 5. 55 children (0.88%) were found to have a slight/mild sensorineural hearing loss. 48 children with slight/mild sensorineural hearing loss and a matched group of 90 children with normal hearing participated in a genetic study investigating mutations in the GJB2 gene, coding for connexin 26, and the presence of the del(GJB6-D13S1830) and del(GJB6-D13S1854) deletions in the GJB6 gene, coding for connexin 30. RESULTS Four of 48 children with slight/mild sensorineural hearing loss were homozygous for the GJB2 V37I change. The four children with homozygous V37I mutations were all of Asian background and analysis of SNPs in or near the GJB2 gene suggests that the V37I mutation arose from a single mutational event in the Asian population. DISCUSSION Based on the prevalence of carriers of this change we conclude that V37I can be a causative mutation that is often associated with slight/mild sensorineural hearing loss. No other children in the slight/mild hearing loss group had a hearing loss related to a GJB2 mutation. One child with normal hearing was homozygous for the R127H change and we conclude that this change does not cause hearing loss. Two children of Asian background were carriers of the V37I mutation. Our data indicate that slight/mild sensorineural hearing loss due to the GJB2 V37I mutation is common in people of Asian background.
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Affiliation(s)
- H-H M Dahl
- Genetic Hearing Research, Murdoch Childrens Research Institute & Department of Paediatrics (Melbourne University), Royal Children's Hospital, Melbourne, Victoria, Australia.
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Bicego M, Beltramello M, Melchionda S, Carella M, Piazza V, Zelante L, Bukauskas FF, Arslan E, Cama E, Pantano S, Bruzzone R, D’Andrea P, Mammano F. Pathogenetic role of the deafness-related M34T mutation of Cx26. Hum Mol Genet 2006; 15:2569-87. [PMID: 16849369 PMCID: PMC2829448 DOI: 10.1093/hmg/ddl184] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Mutations in the GJB2 gene, which encodes the gap junction protein connexin26 (Cx26), are the major cause of genetic non-syndromic hearing loss. The role of the allelic variant M34T in causing hereditary deafness remains controversial. By combining genetic, clinical, biochemical, electrophysiological and structural modeling studies, we have re-assessed the pathogenetic role of the M34T mutation. Genetic and audiological data indicate that the majority of heterozygous carriers and all five compound heterozygotes exhibited an impaired auditory function. Functional expression in transiently transfected HeLa cells showed that, although M34T was correctly synthesized and targeted to the plasma membrane, it inefficiently formed intercellular channels that displayed an abnormal electrical behavior and retained only 11% of the unitary conductance of the wild-type protein (HCx26wt). Moreover, M34T channels failed to support the intercellular diffusion of Lucifer Yellow and the spreading of mechanically induced intercellular Ca2+ waves. When co-expressed together with HCx26wt, M34T exerted dominant-negative effects on cell-cell coupling. Our findings are consistent with a structural model, predicting that the mutation leads to a constriction of the channel pore. These data support the view that M34T is a pathological variant of Cx26 associated with hearing impairment.
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Affiliation(s)
- Massimiliano Bicego
- Dipartimento di Biochimica, Biofisica e Chimica delle Macromolecole, University of Trieste, 34127 Trieste, Italy
| | - Martina Beltramello
- Istituto Veneto di Medicina Molecolare (VIMM), Fondazione per la Ricerca Biomedica Avanzata, 35129 Padova, Italy
| | - Salvatore Melchionda
- Servizio di Genetica Medica, IRCCS-Ospedale Casa Sollievo della Sofferenza, San Giovanni Rotondo, Italy
| | - Massimo Carella
- Servizio di Genetica Medica, IRCCS-Ospedale Casa Sollievo della Sofferenza, San Giovanni Rotondo, Italy
| | - Valeria Piazza
- Istituto Veneto di Medicina Molecolare (VIMM), Fondazione per la Ricerca Biomedica Avanzata, 35129 Padova, Italy
| | - Leopoldo Zelante
- Servizio di Genetica Medica, IRCCS-Ospedale Casa Sollievo della Sofferenza, San Giovanni Rotondo, Italy
| | - Feliksas F. Bukauskas
- Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Edoardo Arslan
- Servizio di Audiologia e Foniatria, University of Padova, 35128 Padova, Italy
| | - Elona Cama
- Servizio di Audiologia e Foniatria, University of Padova, 35128 Padova, Italy
| | - Sergio Pantano
- Istituto Veneto di Medicina Molecolare (VIMM), Fondazione per la Ricerca Biomedica Avanzata, 35129 Padova, Italy
- Consorzio Nazionale Interuniversitario per le Scienze Fisiche della Materia (CNISM)
| | - Roberto Bruzzone
- Département de Neuroscience, Institut Pasteur, 75015 Paris, France
- To whom correspondence should be addressed at: Département de Neuroscience, Institut Pasteur, 25, rue du Dr Roux, 75015 Paris, France. Tel: +33 140613436; Fax: +33 140613421;
| | - Paola D’Andrea
- Dipartimento di Biochimica, Biofisica e Chimica delle Macromolecole, University of Trieste, 34127 Trieste, Italy
| | - Fabio Mammano
- Istituto Veneto di Medicina Molecolare (VIMM), Fondazione per la Ricerca Biomedica Avanzata, 35129 Padova, Italy
- Consorzio Nazionale Interuniversitario per le Scienze Fisiche della Materia (CNISM)
- Dipartimento di Fisica ‘G.Galilei’, Università di Padova, 35131 Padova, Italy
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Cheng X, Li L, Brashears S, Morlet T, Ng SS, Berlin C, Hood L, Keats B. Connexin 26 variants and auditory neuropathy/dys-synchrony among children in schools for the deaf. Am J Med Genet A 2006; 139:13-8. [PMID: 16222667 DOI: 10.1002/ajmg.a.30929] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Genetic and auditory studies of 731 children with severe-to-profound hearing loss in US schools for the deaf and 46 additional children receiving clinical services for hearing loss ranging from moderate to profound demonstrated that mutations in the connexin 26 (GJB2) and connexin 30 (GJB6) genes explain at least 12% of those with nonsyndromic sensorineural deafness. Otoacoustic emissions (OAEs) testing to detect functional outer hair cells indicated that 76 of the children had emissions and therefore may have (as yet unconfirmed) auditory neuropathy/dys-synchrony (AN/AD). Five of these children with OAEs were GJB2 homozygotes or compound heterozygotes with the genotypes 35delG/35delG, W77X/W77X, 35delG/360delGAG, 35delG/V95M, and V84M/M34T. In particular, unilateral AN/AD was confirmed in a child with moderate hearing loss and the 35delG/V95M genotype. Detecting OAEs in individuals with GJB2 mutations suggests that lack of functional gap junctions as a result of GJB2 mutations does not necessarily destroy all outer hair cell function.
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Affiliation(s)
- Xing Cheng
- Department of Genetics, Kresge Hearing Research Laboratory, Louisiana State University Health Sciences Center, New Orleans, Louisiana 70112, USA
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Snoeckx RL, Huygen PLM, Feldmann D, Marlin S, Denoyelle F, Waligora J, Mueller-Malesinska M, Pollak A, Ploski R, Murgia A, Orzan E, Castorina P, Ambrosetti U, Nowakowska-Szyrwinska E, Bal J, Wiszniewski W, Janecke AR, Nekahm-Heis D, Seeman P, Bendova O, Kenna MA, Frangulov A, Rehm HL, Tekin M, Incesulu A, Dahl HHM, du Sart D, Jenkins L, Lucas D, Bitner-Glindzicz M, Avraham KB, Brownstein Z, del Castillo I, Moreno F, Blin N, Pfister M, Sziklai I, Toth T, Kelley PM, Cohn ES, Van Maldergem L, Hilbert P, Roux AF, Mondain M, Hoefsloot LH, Cremers CWRJ, Löppönen T, Löppönen H, Parving A, Gronskov K, Schrijver I, Roberson J, Gualandi F, Martini A, Lina-Granade G, Pallares-Ruiz N, Correia C, Fialho G, Cryns K, Hilgert N, Van de Heyning P, Nishimura CJ, Smith RJH, Van Camp G. GJB2 mutations and degree of hearing loss: a multicenter study. Am J Hum Genet 2005; 77:945-57. [PMID: 16380907 PMCID: PMC1285178 DOI: 10.1086/497996] [Citation(s) in RCA: 385] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2005] [Accepted: 09/08/2005] [Indexed: 01/17/2023] Open
Abstract
Hearing impairment (HI) affects 1 in 650 newborns, which makes it the most common congenital sensory impairment. Despite extraordinary genetic heterogeneity, mutations in one gene, GJB2, which encodes the connexin 26 protein and is involved in inner ear homeostasis, are found in up to 50% of patients with autosomal recessive nonsyndromic hearing loss. Because of the high frequency of GJB2 mutations, mutation analysis of this gene is widely available as a diagnostic test. In this study, we assessed the association between genotype and degree of hearing loss in persons with HI and biallelic GJB2 mutations. We performed cross-sectional analyses of GJB2 genotype and audiometric data from 1,531 persons, from 16 different countries, with autosomal recessive, mild-to-profound nonsyndromic HI. The median age of all participants was 8 years; 90% of persons were within the age range of 0-26 years. Of the 83 different mutations identified, 47 were classified as nontruncating, and 36 as truncating. A total of 153 different genotypes were found, of which 56 were homozygous truncating (T/T), 30 were homozygous nontruncating (NT/NT), and 67 were compound heterozygous truncating/nontruncating (T/NT). The degree of HI associated with biallelic truncating mutations was significantly more severe than the HI associated with biallelic nontruncating mutations (P<.0001). The HI of 48 different genotypes was less severe than that of 35delG homozygotes. Several common mutations (M34T, V37I, and L90P) were associated with mild-to-moderate HI (median 25-40 dB). Two genotypes--35delG/R143W (median 105 dB) and 35delG/dela(GJB6-D13S1830) (median 108 dB)--had significantly more-severe HI than that of 35delG homozygotes.
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Affiliation(s)
- Rikkert L Snoeckx
- Department of Medical Genetics, University of Antwerp, Universiteitsplein 1, B-2610 Antwerp, Belgium
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Seeman P, Malíková M, Rasková D, Bendová O, Groh D, Kubálková M, Sakmaryová I, Seemanová E, Kabelka Z. Spectrum and frequencies of mutations in the GJB2 (Cx26) gene among 156 Czech patients with pre-lingual deafness. Clin Genet 2005; 66:152-7. [PMID: 15253766 DOI: 10.1111/j.1399-0004.2004.00283.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Mutations in the gene gap junction beta 2 (GJB2), the gene for the connexin 26, are the most common cause of pre-lingual deafness worldwide. The mutation 35delG within GJB2 is prevalent in Europe. To date, there are no data about GJB2 mutation spectrum and frequencies from the Czech population. We investigated and report here the spectrum and frequencies of mutations in the GJB2 gene among 156 unrelated, congenital deafness Czech patients. Allele-specific polymerase chain reaction, together with fluorescent fragment analysis, were used for the detection of the 35delG mutation. The entire coding region of the GJB2 was directly sequenced in all patients who were not homozygous for the 35delG. No pathogenic mutation was detected in 51.9% of patients. At least one pathogenic mutation was found in 48.1% of patients, and both pathogenic mutations were detected in 37.8% of patients. Single mutations in a heterozygous state were detected in 10.3% of patients. The mutation 35delG accounts for 82.8% of detected disease mutations, Trp24stop accounts for 9.7% of pathogenic alleles and was found in patients with gypsy heritage. Mutation 313del14 accounts for 3.7% of pathogenic alleles. The frequency of 35delG heterozygotes in the Czech Republic is 1 : 29.6. Testing for only the three most common mutations would detect over 96% of all pathogenic alleles in the Czech Republic.
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Affiliation(s)
- P Seeman
- Department of Child Neurology, DNA Laboratory, Charles University Prague, 2nd School of Medicine, Prague, Czech Republic
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Roux AF, Pallares-Ruiz N, Vielle A, Faugère V, Templin C, Leprevost D, Artières F, Lina G, Molinari N, Blanchet P, Mondain M, Claustres M. Molecular epidemiology of DFNB1 deafness in France. BMC MEDICAL GENETICS 2004; 5:5. [PMID: 15070423 PMCID: PMC385234 DOI: 10.1186/1471-2350-5-5] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 12/10/2003] [Accepted: 03/06/2004] [Indexed: 11/23/2022]
Abstract
Background Mutations in the GJB2 gene have been established as a major cause of inherited non syndromic deafness in different populations. A high number of sequence variations have been described in the GJB2 gene and the associated pathogenic effects are not always clearly established. The prevalence of a number of mutations is known to be population specific, and therefore population specific testing should be a prerequisite step when molecular diagnosis is offered. Moreover, population studies are needed to determine the contribution of GJB2 variants to deafness. We present our findings from the molecular diagnostic screening of the GJB2 and GJB6 genes over a three year period, together with a population-based study of GJB2 variants. Methods and results Molecular studies were performed using denaturing High Performance Liquid Chromatograghy (DHPLC) and sequencing of the GJB2 gene. Over the last 3 years we have studied 159 families presenting sensorineural hearing loss, including 84 with non syndromic, stable, bilateral deafness. Thirty families were genotyped with causative mutations. In parallel, we have performed a molecular epidemiology study on more than 3000 dried blood spots and established the frequency of the GJB2 variants in our population. Finally, we have compared the prevalence of the variants in the hearing impaired population with the general population. Conclusion Although a high heterogeneity of sequence variation was observed in patients and controls, the 35delG mutation remains the most common pathogenic mutation in our population. Genetic counseling is dependent on the knowledge of the pathogenicity of the mutations and remains difficult in a number of cases. By comparing the sequence variations observed in hearing impaired patients with those sequence variants observed in general population, from the same ethnic background, we show that the M34T, V37I and R127H variants can not be responsible for profound or severe deafness.
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Affiliation(s)
- Anne-Françoise Roux
- Laboratoire de Génétique Moléculaire, CHU Montpellier, IURC, Montpellier, France
| | | | - Anne Vielle
- Laboratoire de Génétique Moléculaire, CHU Montpellier, IURC, Montpellier, France
| | - Valérie Faugère
- Laboratoire de Génétique Moléculaire, CHU Montpellier, IURC, Montpellier, France
| | - Carine Templin
- Laboratoire de Génétique Moléculaire, CHU Montpellier, IURC, Montpellier, France
| | - Dorothée Leprevost
- Laboratoire de Génétique Moléculaire, CHU Montpellier, IURC, Montpellier, France
| | - Françoise Artières
- Service D'Audiophonologie, Institut St-Pierre, Palavas-Les-Flots, France
| | | | - Nicolas Molinari
- Laboratoire de Biostatistique, Epidémiolgie et Recherche Clinique, IURC, Montpellier
| | | | | | - Mireille Claustres
- Laboratoire de Génétique Moléculaire, CHU Montpellier, IURC, Montpellier, France
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