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Sharma N, Kumari D, Panigrahi I, Khetarpal P. A systematic review of the monogenic causes of Non-Syndromic Hearing Loss (NSHL) and discussion of Current Diagnosis and Treatment options. Clin Genet 2023; 103:16-34. [PMID: 36089522 DOI: 10.1111/cge.14228] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Revised: 09/02/2022] [Accepted: 09/06/2022] [Indexed: 12/13/2022]
Abstract
Hearing impairment is one of the most widespread inheritable sensory disorder affecting at least 1 in every 1000 born. About two-third of hereditary hearing loss (HHL) disorders are non-syndromic. To provide comprehensive update of monogenic causes of non-syndromic hearing loss (NSHL), literature search has been carried out with appropriate keywords in the following databases-PubMed, Google Scholar, Cochrane library, and Science Direct. Out of 2214 papers, 271 papers were shortlisted after applying inclusion and exclusion criterion. Data extracted from selected papers include information about gene name, identified pathogenic variants, ethnicity of the patient, age of onset, gender, title, authors' name, and year of publication. Overall, pathogenic variants in 98 different genes have been associated with NSHL. These genes have important role to play during early embryonic development in ear structure formation and hearing development. Here, we also review briefly the recent information about diagnosis and treatment approaches. Understanding pathogenic genetic variants are helpful in the management of affected and may offer targeted therapies in future.
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Affiliation(s)
- Nandita Sharma
- Department of Human Genetics and Molecular Medicine, School of Health Sciences, Central University of Punjab, Bathinda, India
| | - Divya Kumari
- Department of Pediatrics Medicine, Post Graduate Institute of Medical Education and Research, Chandigarh, India
| | - Inusha Panigrahi
- Department of Pediatrics Medicine, Post Graduate Institute of Medical Education and Research, Chandigarh, India
| | - Preeti Khetarpal
- Department of Human Genetics and Molecular Medicine, School of Health Sciences, Central University of Punjab, Bathinda, India
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Silva VAR, Pauna HF, Lavinsky J, Hyppolito MA, Vianna MF, Leal M, Massuda ET, Hamerschmidt R, Bahmad F, Cal RV, Sampaio ALL, Felix F, Chone CT, Castilho AM. Task force Guideline of Brazilian Society of Otology ‒ hearing loss in children - Part I ‒ Evaluation. Braz J Otorhinolaryngol 2022; 89:159-189. [PMID: 36529647 PMCID: PMC9874360 DOI: 10.1016/j.bjorl.2022.11.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Accepted: 11/14/2022] [Indexed: 11/29/2022] Open
Abstract
OBJECTIVES To provide an overview of the main evidence-based recommendations for the diagnosis of hearing loss in children and adolescents aged 0 to 18 years. METHODS Task force members were educated on knowledge synthesis methods, including electronic database search, review and selection of relevant citations, and critical appraisal of selected studies. Articles written in English or Portuguese on childhood hearing loss were eligible for inclusion. The American College of Physicians' guideline grading system and the American Thyroid Association's guideline criteria were used for critical appraisal of evidence and recommendations for therapeutic interventions. RESULTS The evaluation and diagnosis of hearing loss: universal newborn hearing screening, laboratory testing, congenital infections (especially cytomegalovirus), genetic testing and main syndromes, radiologic imaging studies, vestibular assessment of children with hearing loss, auditory neuropathy spectrum disorder, autism spectrum disorder, and noise-induced hearing loss. CONCLUSIONS Every child with suspected hearing loss has the right to diagnosis and appropriate treatment if necessary. This task force considers 5 essential rights: (1) Otolaryngologist consultation; (2) Speech assessment and therapy; (3) Diagnostic tests; (4) Treatment; (5) Ophthalmologist consultation.
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Affiliation(s)
- Vagner Antonio Rodrigues Silva
- Universidade Estadual de Campinas (Unicamp), Faculdade de Ciências Médicas, Departamento de Otorrinolaringologia e Cirurgia de Cabeça e Pescoço, Campinas, SP, Brazil.
| | - Henrique Furlan Pauna
- Hospital Universitário Cajuru, Departamento de Otorrinolaringologia, Curitiba, PR, Brazil
| | - Joel Lavinsky
- Universidade Federal do Rio Grande do Sul (UFRGS), Departamento de Cirurgia, Porto Alegre, RS, Brazil
| | - Miguel Angelo Hyppolito
- Universidade de São Paulo (USP), Faculdade de Medicina de Ribeirão Preto, Departamento de Oftalmologia, Otorrinolaringologia e Cirurgia de Cabeça e Pescoço, Ribeirão Preto, SP, Brazil
| | - Melissa Ferreira Vianna
- Irmandade Santa Casa de Misericórdia de São Paulo, Departamento de Otorrinolaringologia, São Paulo, SP, Brazil
| | - Mariana Leal
- Universidade Federal de Pernambuco (UFPE), Departamento de Cirurgia, Recife, PE, Brazil
| | - Eduardo Tanaka Massuda
- Universidade de São Paulo (USP), Faculdade de Medicina de Ribeirão Preto, Departamento de Oftalmologia, Otorrinolaringologia e Cirurgia de Cabeça e Pescoço, Ribeirão Preto, SP, Brazil
| | - Rogério Hamerschmidt
- Universidade Federal do Paraná (UFPR), Hospital de Clínicas, Departamento de Otorrinolaringologia e Cirurgia de Cabeça e Pescoço, Curitiba, PR, Brazil
| | - Fayez Bahmad
- Universidade de Brasília (UnB), Programa de Pós-Graduação em Ciências da Saúde, Brasília, DF, Brazil; Instituto Brasiliense de Otorrinolaringologia (IBO), Brasília, DF, Brazil
| | - Renato Valério Cal
- Centro Universitário do Estado do Pará (CESUPA), Departamento de Otorrinolaringologia, Belém, PA, Brazil
| | - André Luiz Lopes Sampaio
- Universidade de Brasília (UnB), Faculdade de Medicina, Laboratório de Ensino e Pesquisa em Otorrinolaringologia, Brasília, DF, Brazil
| | - Felippe Felix
- Universidade Federal do Rio de Janeiro (UFRJ), Hospital Universitário Clementino Fraga Filho (HUCFF), Departamento de Otorrinolaringologia, Rio de Janeiro, RJ, Brazil
| | - Carlos Takahiro Chone
- Universidade Estadual de Campinas (Unicamp), Faculdade de Ciências Médicas, Departamento de Otorrinolaringologia e Cirurgia de Cabeça e Pescoço, Campinas, SP, Brazil
| | - Arthur Menino Castilho
- Universidade Estadual de Campinas (Unicamp), Faculdade de Ciências Médicas, Departamento de Otorrinolaringologia e Cirurgia de Cabeça e Pescoço, Campinas, SP, Brazil
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Lezirovitz K, Mingroni-Netto RC. Genetic etiology of non-syndromic hearing loss in Latin America. Hum Genet 2021; 141:539-581. [PMID: 34652575 DOI: 10.1007/s00439-021-02354-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2021] [Accepted: 08/23/2021] [Indexed: 12/16/2022]
Abstract
Latin America comprises all countries from South and Central America, in addition to Mexico. It is characterized by a complex mosaic of regions with heterogeneous genetic profiles regarding the geographical origin of the ancestors and proportions of admixture between the Native American, European and African components. In the first years following the findings of the role of the GJB2/GJB6 genes in the etiology of hearing loss, most scientific investigations about the genetics of hearing loss in Latin America focused on assessing the frequencies of pathogenic variants in these genes. More recently, modern techniques allowed researchers in Latin America to make exciting contributions to the finding of new candidate genes, novel mechanisms of inheritance in previously known genes, and characterize a wide diversity of variants, many of them unique to Latin America. This review aimed to provide a general landscape of the genetic studies about non-syndromic hearing loss in Latin America and their main scientific contributions. It allows the conclusion that, although there are similar contributions of some genes, such as GJB2/GJB6, when compared to European and North American countries, Latin American populations revealed some peculiarities that indicate the need for tailored strategies of screening and diagnosis to specific geographic regions.
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Affiliation(s)
- Karina Lezirovitz
- Laboratório de Otorrinolaringologia/LIM32, Faculdade de Medicina, Hospital das Clínicas, Universidade de São Paulo, São Paulo, SP, Brazil.
| | - Regina Célia Mingroni-Netto
- Departamento de Genética e Biologia Evolutiva, Centro de Pesquisas sobre o Genoma Humano e Células-Tronco, Instituto de Biociências, Universidade de São Paulo, São Paulo, Brazil
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Neagu A, Mocanu AI, Bonciu A, Coadă G, Mocanu H. Prevalence of GJB2 gene mutations correlated to presence of clinical and environmental risk factors in the etiology of congenital sensorineural hearing loss of the Romanian population. Exp Ther Med 2021; 21:612. [PMID: 33936269 DOI: 10.3892/etm.2021.10044] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Accepted: 02/19/2021] [Indexed: 11/05/2022] Open
Abstract
Although etiologically heterogeneous at least 50% of all early on-set hearing losses have a genetic cause and of these, the large majority, 75-80% are most probably autosomal recessive and 70% are non-syndromic. The rest of the congenital hearing losses are determined by clinical and environmental factors such as ototoxic medication, prematurity, and complications at birth. During the last decade it became clear that 50-80% of all such afflictions result from mutations in a single gene, GJB2, which encodes the protein Connexin 26. In order to, at least partially clarify this problem, especially in an emerging country such as Romania, where the problem is not studied adequately, we developed a comprehensive study of genetic, clinical and environmental risk factors for congenital hearing loss. The two most common variations of this gene, 35delG and W24X in children with positive diagnosis of bilateral severe to profound sensorineural hearing loss were investigated. A cohort of 34 children (20 female and 14 male), ages between 2 and 10 (mean age 4.62 years), coming from 33 non-related families were evaluated. All cases were diagnosed with severe or profound bilateral congenital SNHL. A statistical comparison of genetic and environmental/clinical prevalence was also attempted since the presence of a genetic disorder cannot rule out the role of other documented risk factors in the etiology of SNHL. The results showed that, 29.4% of cases (10/34) were homozygotic for the 35delG mutation 35delG/35delG), also known as genotype Δ/Δ. 5.88% of cases (2/34) belong to the heterozygotic bi-genic group 35delG/W24X. The clinical factors with high statistical significance for SNHL in a non-genetic group have no significance for genetic SNHL patients. Thus, the present study confirms the relatively high prevalence of the 35delG and W24X mutations in cases of congenital non-syndromic severe of profound bilateral SNHL.
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Affiliation(s)
- Alexandra Neagu
- Department of ENT&HNS, 'Marie S. Curie' Emergency Children Hospital Bucharest, 041434 Bucharest, Romania
| | - Adela-Ioana Mocanu
- Department of ENT&HNS, Bucharest Emergency University Hospital, 050098 Bucharest, Romania
| | - Alexandru Bonciu
- Department of ENT&HNS, 'Dr. Carol Davila' Central Military Emergency University Hospital, 010825 Bucharest, Romania
| | - Gabriella Coadă
- Department of ENT&HNS, 'Sfânta Maria' Clinical Hospital, 011172 Bucharest, Romania
| | - Horia Mocanu
- Department of ENT&HNS, Faculty of Medicine, 'Titu Maiorescu' University, 031593 Bucharest, Romania
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Pandya A, O'Brien A, Kovasala M, Bademci G, Tekin M, Arnos KS. Analyses of del(GJB6-D13S1830) and del(GJB6-D13S1834) deletions in a large cohort with hearing loss: Caveats to interpretation of molecular test results in multiplex families. Mol Genet Genomic Med 2020; 8:e1171. [PMID: 32067424 PMCID: PMC7196463 DOI: 10.1002/mgg3.1171] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Revised: 01/24/2020] [Accepted: 01/30/2020] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND Mutations involving the closely linked GJB2 and GJB6 at the DFNB1 locus are a common genetic cause of profound congenital hearing loss in many populations. In some deaf GJB2 heterozygotes, a 309 kb deletion involving the GJB6 has been found to be the cause for hearing loss when inherited in trans to a GJB2 mutation. METHODS We screened 2,376 probands from a National DNA Repository of deaf individuals. RESULTS Fifty-two of 318 heterozygous probands with pathogenic GJB2 sequence variants had a GJB6 deletion. Additionally, eight probands had an isolated heterozygous GJB6 deletion that did not explain their hearing loss. In two deaf subjects, including one proband, a homozygous GJB6 deletion was the cause for their hearing loss, a rare occurrence not reported to date. CONCLUSION This study represents the largest US cohort of deaf individuals harboring GJB2 and GJB6 variants, including unique subsets of families with deaf parents. Testing additional members to clarify the phase of GJB2/GJB6 variants in multiplex families was crucial in interpreting clinical significance of the variants in the proband. It highlights the importance of determining the phase of GJB2/GJB6 variants when interpreting molecular test results especially in multiplex families with assortative mating.
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Affiliation(s)
- Arti Pandya
- Department of Pediatrics, Division of Genetics and Metabolism, UNC Chapel Hill, Chapel Hill, NC, USA
| | - Alexander O'Brien
- Department of Pediatrics, Division of Genetics and Metabolism, UNC Chapel Hill, Chapel Hill, NC, USA
| | - Michael Kovasala
- Department of Pediatrics, Division of Genetics and Metabolism, UNC Chapel Hill, Chapel Hill, NC, USA
| | - Guney Bademci
- Dr. John T. Macdonald Foundation Department of Human Genetics, John P. Hussman Institute for Human Genomics, University of Miami, Miami, FL, USA
| | - Mustafa Tekin
- Dr. John T. Macdonald Foundation Department of Human Genetics, John P. Hussman Institute for Human Genomics, University of Miami, Miami, FL, USA
| | - Kathleen S Arnos
- Department of Science, Technology, & Mathematics, Gallaudet University, Washington, DC, USA
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Bouzaher MH, Worden CP, Jeyakumar A. Systematic Review of Pathogenic GJB2 Variants in the Latino Population. Otol Neurotol 2020; 41:e182-e191. [PMID: 31834214 DOI: 10.1097/mao.0000000000002505] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
OBJECTIVES Define the extent to which GJB2-related hearing loss is responsible for non-syndromic hearing loss (NSHL) in the Latino population. METHODS Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines were followed. PubMed and MEDLINE were accessed from 1966 to 2019 using permutations of the MeSH terms: "Hearing Loss," "Hearing Impairment," "Deafness," "Latin American," "Latino," "GJB2," and "Genetic." Additionally, countries designated as Latino by the US Office of Management and Bureau were cross-referenced as key terms against the aforementioned search criteria. Exclusion criteria included non-English publications, a non-Latino study population, and literature not investigating GJB2. An allele frequency analysis of pathogenic GJB2 variants in the Latino population was performed and stratified by country of origin and reported ethnicity. RESULTS One hundred twenty two unique studies were identified of which 64 met our inclusion criteria. Forty three studies were included in the GJB2 systematic review. A total of 38 pathogenic GJB2 variants were identified across 20 countries in the Latino population. The prevalence of pathogenic GJB2 variants varied by country; however, were generally uncommon with the exception of c.35delG (p.Gly12Valfs*) which displayed an allele frequency of 3.1% in the combined Latino population; ranging from 21% in Colombia to 0% in Guatemala. CONCLUSION Variation in the prevalence of pathogenic GJB2 variants by country likely reflect the heterogeneous nature of ethnic ancestral contributions to the Latino population. Additional research utilizing next generation sequencing might aid in the development of assays for high throughput diagnosis of inherited hearing loss in the multitude of ethnic sub-groups that comprise this and other traditionally marginalized populations.
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Affiliation(s)
| | | | - Anita Jeyakumar
- Division of Otolaryngology, Department of Surgery, Akron Children's Hospital, Akron, Ohio
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Schüffner RDOA, Nascimento KL, Dias FA, Silva PHTD, Pires WGB, Cipriano NM, Santos LLD. Molecular study of hearing loss in Minas Gerais, Brazil. Braz J Otorhinolaryngol 2019; 86:327-331. [PMID: 30837189 PMCID: PMC9422642 DOI: 10.1016/j.bjorl.2018.12.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2018] [Revised: 11/19/2018] [Accepted: 12/15/2018] [Indexed: 01/02/2023] Open
Abstract
Introduction Deafness is the most frequent sensory deficit in humans. Incidence is estimated at 4:1000 births in Brazil. Specific programs for clinical care of patients with hearing loss are still scarce in Brazil and the issue is an important public health problem. Objective To determine the frequency of 35delG and D13S1830 mutations in GJB2 and GJB6 genes respectively in patients with non-syndromic sensorineural hearing loss from Minas Gerais, Brazil. Methods This research involved 53 individuals, who were assessed by a questionnaire for predicting the possibility of non-syndromic deafness and for data collecting. Samples were tested for the presence of the 35delG mutation in GJB2 gene and D13S1830 in GJB6 gene by polymerase chain reaction and restriction enzyme digestion. Results Epidemiological research has shown that the majority of the subjects are unaware of the etiology and the pathogenesis of hearing loss. In 9 patients (16.98%), 35delG mutation was found in heterozygosis and the allele frequency was estimate to be around 8.5%. Although 9.61% of the patients reported having some degree of consanguinity between the parents and 12.08% reported other cases of deafness in their families, this mutation was not found in homozygosis. The D13S1830 mutation was not found in this study. Conclusion This research describes for the first time the frequency of the 35delG and D13S1830 mutation in hearing-impaired individuals from Minas Gerais, Brazil, and the collected data reinforce the need for further studies in this population due to heterogeneity of hearing loss.
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Affiliation(s)
| | | | - Fábio André Dias
- Universidade Federal de São João del-Rei, Divinópolis, MG, Brazil
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Manzoli GN, Bademci G, Acosta AX, Félix TM, Cengiz FB, Foster J, Da Silva DSD, Menendez I, Sanchez-Pena I, Tekin D, Blanton SH, Abe-Sandes K, Liu XZ, Tekin M. Targeted Resequencing of Deafness Genes Reveals a Founder MYO15A Variant in Northeastern Brazil. Ann Hum Genet 2016; 80:327-331. [PMID: 27870113 PMCID: PMC5127167 DOI: 10.1111/ahg.12177] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2016] [Revised: 08/23/2016] [Accepted: 10/06/2016] [Indexed: 11/29/2022]
Abstract
Identifying the genetic etiology in a person with hearing loss (HL) is challenging due to the extreme genetic heterogeneity in HL and the population-specific variability. In this study, after excluding GJB2 variants, targeted resequencing of 180 deafness-related genes revealed the causative variants in 11 of 19 (58%) Brazilian probands with autosomal recessive HL. Identified pathogenic variants were in MYO15A (10 families) and CLDN14 (one family). Remarkably, the MYO15A p.(Val1400Met) variant was identified in eight families from the city of Monte Santo in the northeast region of Brazil. Haplotype analysis of this variant was consistent with a single founder. No other cases with this variant were detected among 105 simplex cases from other cities of northeastern Brazil, suggesting that this variant is confined to a geographical region. This study suggests that it is feasible to develop population-specific screening for deafness variants once causative variants are identified in different geographical groups.
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Affiliation(s)
- Gabrielle N Manzoli
- John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, FL, 33136, USA
- Gonçalo Moniz Research Center (CPqGM), Oswaldo Cruz Foundation (FIOCRUZ), Salvador, Bahia, Brazil
| | - Guney Bademci
- John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, FL, 33136, USA
| | - Angelina X Acosta
- Gonçalo Moniz Research Center (CPqGM), Oswaldo Cruz Foundation (FIOCRUZ), Salvador, Bahia, Brazil
| | - Têmis M Félix
- Serviço de Genética Médica, Hospital de Clinicas de Porto Alegre, Brazil
| | - F Basak Cengiz
- John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, FL, 33136, USA
| | - Joseph Foster
- John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, FL, 33136, USA
| | - Danniel S Dias Da Silva
- Gonçalo Moniz Research Center (CPqGM), Oswaldo Cruz Foundation (FIOCRUZ), Salvador, Bahia, Brazil
| | - Ibis Menendez
- John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, FL, 33136, USA
| | - Isalis Sanchez-Pena
- John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, FL, 33136, USA
| | - Demet Tekin
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, FL, 33136, USA
| | - Susan H Blanton
- John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, FL, 33136, USA
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, FL, 33136, USA
- Dr. John T. Macdonald Foundation Department of Human Genetics, University of Miami Miller School of Medicine, Miami, FL, 33136, USA
| | - Kiyoko Abe-Sandes
- Gonçalo Moniz Research Center (CPqGM), Oswaldo Cruz Foundation (FIOCRUZ), Salvador, Bahia, Brazil
| | - Xue Zhong Liu
- John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, FL, 33136, USA
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, FL, 33136, USA
| | - Mustafa Tekin
- John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, FL, 33136, USA
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, FL, 33136, USA
- Dr. John T. Macdonald Foundation Department of Human Genetics, University of Miami Miller School of Medicine, Miami, FL, 33136, USA
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Amorini M, Romeo P, Bruno R, Galletti F, Di Bella C, Longo P, Briuglia S, Salpietro C, Rigoli L. Prevalence of Deafness-Associated Connexin-26 (GJB2) and Connexin-30 (GJB6) Pathogenic Alleles in a Large Patient Cohort from Eastern Sicily. Ann Hum Genet 2015; 79:341-349. [PMID: 26096904 DOI: 10.1111/ahg.12120] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2014] [Accepted: 03/24/2015] [Indexed: 11/28/2022]
Abstract
Mutations in the gene encoding the gap junction protein connexin 26 (GJB2) and connexin 30 (GJB6) have been shown to be a major contributor to prelingual, sensorineural, nonsyndromic deafness. The aim of this study was to characterize and establish the prevalence of GJB2 and GJB6 gene alterations in 196 patients affected by sensorineural, nonsyndromic hearing loss, from Eastern Sicily. We performed sequence analysis of GJB2 and identified sequence variants in 68 out of 196 patients (34.7%); (28 homozygous for c.35delG, 22 compound heterozygous and 11 with only one variant allele). We found 12 different allelic variants, the most prevalent being c.35delG, which was found on 89 chromosomes (65.5%), followed by other alleles with different frequencies (p.E47X, c.-23+1G>A, p.L90P, p.R184W, p.M34T, c.167delT, p.R127H, p.M163V, p.V153I, p.W24X, and p.T8M). Importantly, for the first time we present the frequency and spectrum of GJB2 mutations in NSHL patients from Eastern Sicily. No alterations were found in the GJB6 gene, confirming that alterations in this gene are uncommon in our geographic area. Note that 65.3% and 23.5% of our patients, respectively were found to be negative or carriers by GJB2 molecular screening. This emphasizes the need to broaden the genetic analysis to other genes involved in hearing loss.
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Affiliation(s)
- Maria Amorini
- Department of Paediatrics, University of Messina, Italy
| | | | - Rocco Bruno
- Department of Experimental Medical-Surgery, Specialist and Odontostomatological Science, Otorhinolaringology and Auditory Microsurgery Unit, University of Messina, Italy
| | - Francesco Galletti
- Department of Experimental Medical-Surgery, Specialist and Odontostomatological Science, Otorhinolaringology and Auditory Microsurgery Unit, University of Messina, Italy
| | | | - Patrizia Longo
- Department of Experimental Medical-Surgery, Specialist and Odontostomatological Science, Otorhinolaringology and Auditory Microsurgery Unit, University of Messina, Italy
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Chan DK, Chang KW. GJB2-associated hearing loss: Systematic review of worldwide prevalence, genotype, and auditory phenotype. Laryngoscope 2013; 124:E34-53. [DOI: 10.1002/lary.24332] [Citation(s) in RCA: 183] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/10/2013] [Indexed: 12/17/2022]
Affiliation(s)
- Dylan K. Chan
- Department of Otolaryngology-Head and Neck Surgery; University of California; San Francisco U.S.A
| | - Kay W. Chang
- Department of Otolaryngology-Head and Neck Surgery; Stanford University School of Medicine; Stanford California U.S.A
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Manzoli GN, Abe-Sandes K, Bittles AH, da Silva DSD, Fernandes LDC, Paulon RMC, de Castro ICS, Padovani CMCA, Acosta AX. Non-syndromic hearing impairment in a multi-ethnic population of Northeastern Brazil. Int J Pediatr Otorhinolaryngol 2013; 77:1077-82. [PMID: 23684175 DOI: 10.1016/j.ijporl.2013.04.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/09/2012] [Revised: 03/30/2013] [Accepted: 04/01/2013] [Indexed: 01/28/2023]
Abstract
OBJECTIVE There are many hearing impaired individuals in Monte Santo, a rural municipality in the state of Bahia, Brazil, including multiple familial cases strongly suggestive of a genetic aetiology. METHODS The present study investigated 81 subjects with hearing impairment (HI) recruited from 36 families. Mutations often associated with HI, i.e. the DFNB1 mutations c.35delG in GJB2, deletions del(GJB6-D13S1830) and del(GJB6-D13S1854), and A1555G in the mitochondrial gene MTRNR1 were initially analyzed, with additional mutations in GJB2 identified by sequencing the coding region of the gene. RESULTS Seven different mutations were present in GJB2 with mutations c.35delG and p.Arg75Gln, which are known to be pathogenic, identified in 37.0% of the subjects. Individuals homozygous for the c.35delG mutation were diagnosed in eight families, corresponding to 24.7% of unrelated individuals with nonsyndromic hearing impairment (NSHI), and an additional heterozygote for this mutation was present in a single family. Ten individuals (12.4%) in another family were heterozygous for the mutation p.Arg75Gln. CONCLUSIONS Significant heterogeneity was observed in the alleles and patterns of NSHI inheritance among the subjects studied, probably due to the extensive inter-ethnic admixture that characterizes the peoples of Brazil, together with a high prevalence of community endogamy and consanguineous marriage.
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Affiliation(s)
- Gabrielle N Manzoli
- Advanced Laboratory of Public Health/Gonçalo Moniz Research Center (CPqGM), Oswaldo Cruz Foundation (FIOCRUZ), Salvador, Bahia, Brazil
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Esteves MCBN, de Lima Isaac M, Francisco AM, da Silva Junior WA, Ferreira CA, Dell'Aringa AHB. Analysis of the presence of the GJB6 mutations in patients heterozygous for GJB2 mutation in Brazil. Eur Arch Otorhinolaryngol 2013; 271:695-9. [PMID: 23553242 DOI: 10.1007/s00405-013-2468-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2012] [Accepted: 03/20/2013] [Indexed: 10/27/2022]
Abstract
Mutations in the GJB2 gene, mainly 35delG, are responsible for most autosomal recessive inherited genetic hearing loss. The audiometric standard of these hearing losses remains inconsistent and other genes, such as GJB6, have been involved in association with GJB2. The objective of the study was to identify the deletions del(GJB6-D13S1830) and del(GJB6-D13S1854) in patients heterozygous for 35delG/GJB2 and analyze the phenotype they present. 101 patients with mild to profound degree of sensorineural hypoacusis were evaluated. The allele-specific PCR technique was used to identify 35delG. The del(GJB6-D13S1830) and del(GJB6-D13S1854) were identified through the PCR multiplex technique. 90% of the subjects presented a normal genotype for the analyzed mutations; 6.93% were shown to be heterozygous for 35delG/GJB2 and 1% presented compound heterozygosis GJB2/GJB6). The data found reinforced the hypothesis of an interaction of more than one gene as the cause of autosomal recessive genetic hearing loss and emphasized the importance of an early diagnosis for appropriate intervention.
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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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Jian W, Ying-ying F, Shu-juan W, Peng-Fei L, Jin-ling W, Jian-hua Q. Variants of OTOF and PJVK genes in Chinese patients with auditory neuropathy spectrum disorder. PLoS One 2011; 6:e24000. [PMID: 21935370 PMCID: PMC3174136 DOI: 10.1371/journal.pone.0024000] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2011] [Accepted: 07/27/2011] [Indexed: 12/21/2022] Open
Abstract
Background Mutations in OTOF and PJVK genes cause DFNB9 and DFNB59 types of hearing loss, respectively. The patients carrying pathogenic mutations in either of these genes may show the typical phenotype of auditory neuropathy spectrum disorder (ANSD). The aim of the present study was to identify OTOF and PJVK mutations in sporadic ANSD patients. Methods and Findings A total of 76 unrelated Chinese non-syndromic ANSD patients were sequenced on the gene OTOF and PJVK exon by exon. Variants were valued in 105 controls with normal hearing to verify the carrying rate. We identified one pathogenic mutation (c.1194T>A) and three novel, possibly pathogenic, variants (c.3570+2T>C, c.4023+1 G>A, and c.1102G>A) in the OTOF gene, and one novel, possibly pathogenic, variant (c.548G>A) in PJVK. Moreover, we found three novel missense mutations within the exons of OTOF. Conclusions As we identified 4 and 1 possible pathogenic variants of the OTOF gene and the PJVK gene, respectively, we believe that screening in these genes are important in sporadic ANSD patients. The pathogenicity of these novel mutations needs further study because of their single heterozygous nature. Knowledge on the mutation spectra of these genes in Chinese would be beneficial in understanding the genetic character of this worldwide disease.
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Affiliation(s)
- Wang Jian
- Deafness Gene Diagnosis, PLA Otolaryngology-Head and Neck Surgery Center, Xijing Hospital, Fourth Military Medical University, Xi'an, Shannxi, China
| | - Fan Ying-ying
- Department of Anesthesiology, Stomatological College, Fourth Military Medical University, Xi'an, Shannxi, China
| | - Wang Shu-juan
- Deafness Gene Diagnosis, PLA Otolaryngology-Head and Neck Surgery Center, Xijing Hospital, Fourth Military Medical University, Xi'an, Shannxi, China
| | - Liang Peng-Fei
- Deafness Gene Diagnosis, PLA Otolaryngology-Head and Neck Surgery Center, Xijing Hospital, Fourth Military Medical University, Xi'an, Shannxi, China
| | - Wang Jin-ling
- PLA Otolaryngology-Head and Neck Surgery Center, Xijing Hospital, Fourth Military Medical University, Xi'an, Shannxi, China
| | - Qiu Jian-hua
- Deafness Gene Diagnosis, PLA Otolaryngology-Head and Neck Surgery Center, Xijing Hospital, Fourth Military Medical University, Xi'an, Shannxi, China
- PLA Otolaryngology-Head and Neck Surgery Center, Xijing Hospital, Fourth Military Medical University, Xi'an, Shannxi, China
- * E-mail:
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da Silva-Costa SM, Martins FTA, Pereira T, Pomilio MCA, Marques-de-Faria AP, Sartorato EL. Searching for digenic inheritance in deaf Brazilian individuals using the multiplex ligation-dependent probe amplification technique. Genet Test Mol Biomarkers 2011; 15:849-53. [PMID: 21728791 DOI: 10.1089/gtmb.2011.0034] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Mutations in the genes coding for connexin 26 (Cx26), connexin 30 (Cx30), and connexin 31 (Cx31) are the main cause of autosomal recessive nonsyndromic sensorineural hearing loss (AR-NSNHL). The 35delG mutation is the most frequent in the majority of Caucasian populations and may account for up to 70% of all GJB2 mutations. As a large number of affected individuals (10%-40%) with GJB2 mutations carry only one mutant allele, it has been postulated that the presence of additional mutations in the GJB6 gene (Cx30) explains the deafness condition found in these patients. In the present study, we screened the c.35delG mutation in ~600 unrelated Brazilian patients, with moderate to profound AR-NSNHL. Other point mutations in the coding region of the GJB2 gene were screened by sequencing analysis as well as the IVS 1+1 G>A splice site mutation in the same gene. Digenic mutations including large deletions and duplications were investigated in the Cx26, 30, and 31 genes in monoallelic individuals for mutations in the GJB2 gene. Large deletions and duplications were assessed by multiplex ligation-dependent probe amplification. We found 46 patients with mutations in only one GJB2 allele. Different pathogenic mutations associated with c.35delG were found in 13 patients. Two patients were identified with digenic heterozygous mutations. Our findings contributed to more accurate diagnosis and more appropriate genetic counseling in 28% of patients studied (13/46).
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Affiliation(s)
- Sueli M da Silva-Costa
- Centro de Biologia Molecular e Engenharia Genética, Universidade Estadual de Campinas, Cidade Universitária Zeferino Vaz s/n, Barão Geraldo, Campinas, Brazil
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Cordeiro-Silva MDF, Barbosa A, Santiago M, Provetti M, Dettogni RS, Tovar TT, Rabbi-Bortolini E, Louro ID. Mutation analysis of GJB2 and GJB6 genes in Southeastern Brazilians with hereditary nonsyndromic deafness. Mol Biol Rep 2010; 38:1309-13. [PMID: 20563649 DOI: 10.1007/s11033-010-0231-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2010] [Accepted: 06/11/2010] [Indexed: 11/25/2022]
Abstract
In developed countries deafness has a genetic cause in over 60% of the cases. Contrastingly, in Brazil, it is estimated that only 16% of all deafnesses are caused by genetic factors. Among hereditary hearing deficiencies, approximately half is caused by mutations in the Gap Junction Protein Beta-2 (GJB2) gene, which encodes the protein Connexin 26 (Cx26). There are four mutations in this gene that present high prevalence in specific ethnical groups, namely, 35delG, 167delT, 235delC, and W24X. The 35delG mutation is the most frequent one, occurring in homozygosity or in compound heterozygosity with mutations in the GJB2 and GJB6 genes. This study aims to determine the prevalence of GJB2-35delG, GJB2-167delT, GJB2-235delC, GJB2-W24X, del (GJB6-D13S1830), and del (GJB6-D13S1854) mutations in patients with nonsyndromic deafness in the Espirito Santo State, Brazil. A total of 77 individuals were evaluated, from which 88.3% presented normal genotypes for all analyzed mutations, 1.3% were compound heterozygotes for 35delG-GJB2/D13S1830-GJB6, 1.3% were compound heterozygotes for 35delG/D13S1854-GJB6, 3.9% were homozygotes for the 35delG mutation and 5.2% were heterozygotes for 35delG/GJB2. The frequency of mutant alleles 35delG/GJB2, del (D13S1830/GJB6), and del (D13S1854/GJB6) was 7.8, 0.65, and 0.65%, respectively. Mutations 167delT, 235delC, and W24X were not detected. Determining the prevalence of specific mutations related to inherited deafness in a population can contribute to the development of more efficient and affordable molecular diagnostic protocols, and help in the genetic counseling of patients and their families.
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Affiliation(s)
- Melissa de Freitas Cordeiro-Silva
- Laboratório de Genética e Biologia Molecular, Faculdades Integradas São Pedro-FAESA, Rodovia Serafim Derenzi, 3115, São Pedro, 29048-450, Vitória, ES, Brazil
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da Silva-Costa SM, Coeli FB, Lincoln-de-Carvalho CR, Marques-de-Faria AP, Kurc M, Pereira T, Pomilio MCA, Sartorato EL. Screening for the GJB2 c.-3170 G>A (IVS 1+1 G>A) Mutation in Brazilian Deaf Individuals Using Multiplex Ligation–Dependent Probe Amplification. Genet Test Mol Biomarkers 2009; 13:701-4. [DOI: 10.1089/gtmb.2009.0025] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Sueli Matilde da Silva-Costa
- Laboratório de Genética Molecular Humana, Centro de Biologia Molecular e Engenharia Genética, Universidade Estadual de Campinas, Campinas, Brazil
| | - Fernanda Borchers Coeli
- Laboratório de Genética Molecular Humana, Centro de Biologia Molecular e Engenharia Genética, Universidade Estadual de Campinas, Campinas, Brazil
| | | | | | | | - Tânia Pereira
- Associação Terapêutica de Estimulação Auditiva e Linguagem (ATEAL), Jundiai, Brazil
| | | | - Edi Lúcia Sartorato
- Laboratório de Genética Molecular Humana, Centro de Biologia Molecular e Engenharia Genética, Universidade Estadual de Campinas, Campinas, Brazil
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Maniglia LP, Moreira BCL, da Silva MAOM, Piatto VB, Maniglia JV. Screening of the mitochondrial A1555G mutation in patients with sensorineural hearing loss. Braz J Otorhinolaryngol 2009; 74:731-736. [PMID: 19082356 PMCID: PMC9445927 DOI: 10.1016/s1808-8694(15)31384-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2007] [Accepted: 06/28/2007] [Indexed: 11/29/2022] Open
Abstract
The A1555G mitochondrial mutation is the main alteration associated with aminoglycoside-induced deafness. Aim to investigate the prevalence of the A1555G mutation in patients sensorineural hearing loss patients with and without aminoglycosides antibiotic use. Material and Method a study of 27 cases with deafness as the sample, and 100 neonates with normal hearing as the control group. DNA was extracted from blood leukocyte samples, and specific oligonucleotide primers were designed to amplify the cytochrome b gene and the region which encloses the A1555G mutation of the mitocondrial DNA using the polymerase chain reaction and restriction fragment length polymorphism. Design a cross-sectional case study. Results a region of the cytochrome b gene was amplified and the presence of the mtDNA was confirmed in all of the 127 cases. The A1555G mutation was not found in any of the 27 patients with hearing loss or the control group with 100 neonates. Conclusion the results agree with studies stating that the A1555G mutation is not prevalent in the Americas. There is interest in establishing the real prevalence of this mutation and to investigate other mutations that may cause hearing loss, associated or not with the use of aminoglycosides, in the Brazilian population.
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Affiliation(s)
- Luciano Pereira Maniglia
- Master's degree student, faculty member of the Otorhinolaryngology and Head & Neck Surgery Department, Medical School, S. J. Rio Preto, SP, FAMERP.
| | | | | | | | - José Victor Maniglia
- Livre-docente (habilitation) professor, head of the Otorhinolaryngology and Head & Neck Surgery Department, Medical School, S. J. Rio Preto, SP, FAMERP. Medical School, São José do Rio Preto, SP, FAMERP
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Prevalence of GJB2 (Connexin-26) and GJB6 (Connexin-30) Mutations in a Cohort of 300 Brazilian Hearing-Impaired Individuals: Implications for Diagnosis and Genetic Counseling. Ear Hear 2009; 30:1-7. [PMID: 19125024 DOI: 10.1097/aud.0b013e31819144ad] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Maniglia LP, Moreira BCL, Silva MAOMD, Piatto VB, Maniglia JV. Rastreamento da mutação mitocondrial A1555G em pacientes com deficiência auditiva sensorioneural. ACTA ACUST UNITED AC 2008. [DOI: 10.1590/s0034-72992008000500015] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A mutação mitocondrial A1555G é a principal alteração associada à surdez ocasionada pelo uso de aminoglicosídeos. OBJETIVO: Investigar a prevalência da mutação A1555G em pacientes com deficiência auditiva sensorioneural com e sem uso de antibióticos aminoglicosídeos. MATERIAL E MÉTODO: Estudo em amostras de 27 pacientes com surdez, como casos, e em 100 neonatos, com audição normal, como grupo controle. O DNA foi extraído de leucócitos de amostras de sangue e "primers" específicos foram utilizados para amplificar o gene do citocromo b e a região que abrange a mutação A1555G do DNA mitocondrial, usando as técnicas da Reação em Cadeia da Polimerase e do Polimorfismo no Comprimento de Fragmentos de Restrição. DESENHO CIENTÍFICO: Estudo de casos em corte transversal. RESULTADOS: A região do gene do citocromo b foi amplificada, sendo confirmada a presença do DNA mitocondrial em todas as 127 amostras do estudo. A mutação A1555G não foi identificada nos 27 pacientes com deficiência auditiva e no grupo controle (100 neonatos). CONCLUSÕES: Os resultados são concordantes com estudos que relatam que a mutação A1555G não é prevalente nas Américas. Há interesse na determinação da real prevalência dessa mutação e na investigação de outras mutações que possam ocasionar deficiência auditiva associada ou não ao uso de aminoglicosídeos na população brasileira.
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Interaction between audiology and genetics in the study of a family: the complexity of molecular diagnosis and genetic counseling. Braz J Otorhinolaryngol 2008; 74:698-702. [PMID: 19082351 PMCID: PMC9445928 DOI: 10.1016/s1808-8694(15)31379-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2007] [Accepted: 02/25/2008] [Indexed: 11/22/2022] Open
Abstract
Hearing loss is a multifaceted condition with many etiologies, among which genetic mutation is. Therefore, it is important to connect audiological investigation to etiological diagnosis. Aim this study aims to establish the audiological and genetic profiles of three non-syndromic children with sensorineural hearing loss. Materials and method three brothers aged 3, 5 and 16 were enrolled in this study. They were submitted to behavioral and electrophysiological hearing tests and molecular studies. Results the hearing tests showed moderate to moderately severe bilateral symmetric sensorineural hearing loss and an accentuated descending slope. Transient and Distortion Product Otoacoustic emissions were absent in the two younger children. ABR showed a bilateral moderately severe to severe sensorineural hearing loss. P300 showed bilateral normal latencies in the older brother. Molecular tests showed that the two younger children were heterozygote for mutation 35delG on gene GJB2. Conclusion The combination of speech and hearing tests and genetic analysis allows for the etiologic diagnosis of seemingly similar hearing loss cases, which however display different genetic backgrounds. Molecular studies must be comprehensive enough to avoid precipitated diagnosis which may impair genetic counseling.
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Wu CC, Chen PJ, Chiu YH, Lu YC, Wu MC, Hsu CJ. Prospective Mutation Screening of Three Common Deafness Genes in a Large Taiwanese Cohort with Idiopathic Bilateral Sensorineural Hearing Impairment Reveals a Difference in the Results between Families from Hospitals and Those from Rehabilitation Facilities. Audiol Neurootol 2007; 13:172-81. [DOI: 10.1159/000112425] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2007] [Accepted: 08/29/2007] [Indexed: 11/19/2022] Open
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Utrera R, Ridaura V, Rodríguez Y, Rojas MJ, Mago L, Angeli S, Henríquez O. Detection of the 35delG/GJB2 and del(GJB6-D13S1830) Mutations in Venezuelan Patients with Autosomal Recessive Nonsyndromic Hearing Loss. ACTA ACUST UNITED AC 2007; 11:347-52. [DOI: 10.1089/gte.2006.0526] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- René Utrera
- Departamento de Biología Celular, Universidad Simón Bolívar, Caracas, Venezuela 1081-A
| | - Vanessa Ridaura
- Departamento de Biología Celular, Universidad Simón Bolívar, Caracas, Venezuela 1081-A
| | - Yuryanni Rodríguez
- Departamento de Biología Celular, Universidad Simón Bolívar, Caracas, Venezuela 1081-A
| | - Maria J. Rojas
- Departamento de Biología Celular, Universidad Simón Bolívar, Caracas, Venezuela 1081-A
| | - Leomig Mago
- Departamento de Biología Celular, Universidad Simón Bolívar, Caracas, Venezuela 1081-A
| | - Simón Angeli
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, FL 33101
| | - Oswaldo Henríquez
- Departamento de Otorinolaringología, Hospital San Juan de Dios, Caracas, Venezuela 1081-A
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Oliveira CA, Pimpinati CJ, Alexandrino F, Magna LA, Maciel-Guerra AT, Sartorato EL. Allelic Frequencies of The 35delG Mutation of The GJB2 Gene in Different Brazilian Regions. ACTA ACUST UNITED AC 2007; 11:1-3. [PMID: 17394388 DOI: 10.1089/gte.2006.9994] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Mutations in the GJB2 gene, which encodes the protein connexin 26, are a major cause of autosomal recessive deafness. The most frequent mutation, 35delG, has a carrier frequency as high as 4% in some countries, and this frequency varies in different ethnic groups. Most of the Brazilian population results from interethnic crosses of people from three continents (European, African, and Amerindian), and the proportion of each varies according to the geographical region of the country. To verify if the different ethnic composition of Brazilian regions leads to variable 35delG carrier frequencies, we performed the screening of the 35delG mutation using DNA from dried-blood filter paper samples obtained from 1,856 newborns from 10 cities in different regions. The 35delG mutation was found in 25 individuals (1.35%), indicating an overall carrier frequency of 1:74. This frequency was 1:47 in the north, 1:64 in the southeast, 1:85 in the south and 1:124 in the northeast, but these differences were not significant. The overall frequency of the 35delG allele was estimated as 0.0067, and comparison between expected and observed genotype frequencies indicates that the population is in Hardy-Weinberg equilibrium.
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Affiliation(s)
- C A Oliveira
- Centro de Biologia Molecular e Engenharia Genética/ CBMEG, Laboratório de Genética Humana, Saã Paulo, Brazil
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