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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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Batissoco AC, Pedroso-Campos V, Pardono E, Sampaio-Silva J, Sonoda CY, Vieira-Silva GA, da Silva de Oliveira Longati EU, Mariano D, Hoshino ACH, Tsuji RK, Jesus-Santos R, Abath-Neto O, Bento RF, Oiticica J, Lezirovitz K. Molecular and genetic characterization of a large Brazilian cohort presenting hearing loss. Hum Genet 2021; 141:519-538. [PMID: 34599368 DOI: 10.1007/s00439-021-02372-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Accepted: 09/15/2021] [Indexed: 12/16/2022]
Abstract
Hearing loss is one of the most common sensory defects, affecting 5.5% of the worldwide population and significantly impacting health and social life. It is mainly attributed to genetic causes, but their relative contribution reflects the geographical region's socio-economic development. Extreme genetic heterogeneity with hundreds of deafness genes involved poses challenges for molecular diagnosis. Here we report the investigation of 542 hearing-impaired subjects from all Brazilian regions to search for genetic causes. Biallelic GJB2/GJB6 causative variants were identified in 12.9% (the lowest frequency was found in the Northern region, 7.7%), 0.4% carried GJB2 dominant variants, and 0.6% had the m.1555A > G variant (one aminoglycoside-related). In addition, other genetic screenings, employed in selected probands according to clinical presentation and presumptive inheritance patterns, identified causative variants in 2.4%. Ear malformations and auditory neuropathy were diagnosed in 10.8% and 3.5% of probands, respectively. In 3.8% of prelingual/perilingual cases, Waardenburg syndrome was clinically diagnosed, and in 71.4%, these diagnoses were confirmed with pathogenic variants revealed; seven out of them were novel, including one CNV. All these genetic screening strategies revealed causative variants in 16.2% of the cases. Based on causative variants in the molecular diagnosis and genealogy analyses, a probable genetic etiology was found in ~ 50% of the cases. The present study highlights the relevance of GJB2/GJB6 as a cause of hearing loss in all Brazilian regions and the importance of screening unselected samples for estimating frequencies. Moreover, when a comprehensive screening is not available, molecular diagnosis can be enhanced by selecting probands for specific screenings.
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Affiliation(s)
- Ana Carla Batissoco
- Laboratório de Otorrinolaringologia/LIM 32, Hospital das Clínicas HCFMUSP, Faculdade de Medicina, Universidade de São Paulo, São Paulo, SP, Brasil
- ENT Department, Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, São Paulo, SP, Brasil
| | - Vinicius Pedroso-Campos
- Laboratório de Otorrinolaringologia/LIM 32, Hospital das Clínicas HCFMUSP, Faculdade de Medicina, Universidade de São Paulo, São Paulo, SP, Brasil
| | - Eliete Pardono
- Laboratório de Otorrinolaringologia/LIM 32, Hospital das Clínicas HCFMUSP, Faculdade de Medicina, Universidade de São Paulo, São Paulo, SP, Brasil
- Instituto de Ciências de Saúde da UNIP, São Paulo, SP, Brasil
| | - Juliana Sampaio-Silva
- Laboratório de Otorrinolaringologia/LIM 32, Hospital das Clínicas HCFMUSP, Faculdade de Medicina, Universidade de São Paulo, São Paulo, SP, Brasil
| | - Cindy Yukimi Sonoda
- Laboratório de Otorrinolaringologia/LIM 32, Hospital das Clínicas HCFMUSP, Faculdade de Medicina, Universidade de São Paulo, São Paulo, SP, Brasil
| | - Gleiciele Alice Vieira-Silva
- Laboratório de Otorrinolaringologia/LIM 32, Hospital das Clínicas HCFMUSP, Faculdade de Medicina, Universidade de São Paulo, São Paulo, SP, Brasil
| | | | - Diego Mariano
- Department of Computer Science, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brasil
| | - Ana Cristina Hiromi Hoshino
- ENT Department, Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, São Paulo, SP, Brasil
| | - Robinson Koji Tsuji
- ENT Department, Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, São Paulo, SP, Brasil
| | - Rafaela Jesus-Santos
- Laboratório de Otorrinolaringologia/LIM 32, Hospital das Clínicas HCFMUSP, Faculdade de Medicina, Universidade de São Paulo, São Paulo, SP, Brasil
| | - Osório Abath-Neto
- Departamento de Neurologia, Faculdade de Medicina FMUSP, Universidade de São Paulo, São Paulo, SP, Brasil
| | - Ricardo Ferreira Bento
- Laboratório de Otorrinolaringologia/LIM 32, Hospital das Clínicas HCFMUSP, Faculdade de Medicina, Universidade de São Paulo, São Paulo, SP, Brasil
- ENT Department, Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, São Paulo, SP, Brasil
| | - Jeanne Oiticica
- Laboratório de Otorrinolaringologia/LIM 32, Hospital das Clínicas HCFMUSP, Faculdade de Medicina, Universidade de São Paulo, São Paulo, SP, Brasil
- ENT Department, Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, São Paulo, SP, Brasil
| | - Karina Lezirovitz
- Laboratório de Otorrinolaringologia/LIM 32, Hospital das Clínicas HCFMUSP, Faculdade de Medicina, Universidade de São Paulo, São Paulo, SP, Brasil.
- ENT Department, Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, São Paulo, SP, Brasil.
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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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Carvalho SDCES, Grangeiro CHP, Picanço-Albuquerque CG, Dos Anjos TO, De Molfetta GA, Silva WA, Ferraz VEDF. Contribution of SLC26A4 to the molecular diagnosis of nonsyndromic prelingual sensorineural hearing loss in a Brazilian cohort. BMC Res Notes 2018; 11:546. [PMID: 30068397 PMCID: PMC6071330 DOI: 10.1186/s13104-018-3647-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2018] [Accepted: 07/24/2018] [Indexed: 11/10/2022] Open
Abstract
OBJECTIVE Hereditary hearing loss (HL) is the most common sensorineural disorder in humans. Besides mutations in GJB2 and GJB6 genes, pathogenic variants in the SLC26A4 gene have been reported as a cause of hereditary HL due to its role in the physiology of the inner ear. In this research we wanted to investigate the prevalence of mutations in SLC26A4 in Brazilian patients with nonsyndromic prelingual sensorineural HL. We applied the high-resolution melting technique to screen 88 DNA samples from unrelated deaf individuals that were previously screened for GJB2, GJB6 and MT-RNR1 mutations. RESULTS The frequency of mutations in the SLC26A4 gene was 28.4%. Two novel mutations were found: p.Ile254Val and p.Asn382Lys. The mutation c.-66C>G (rs17154282) in the promoter region of SLC26A4, was the most frequent mutation found and was significantly associated with nonsyndromic prelingual sensorineural HL. After mutations in the GJB2, GJB6 and mitochondrial genes, SLC26A4 mutations are considered the next most common cause of hereditary HL in Brazilian as well as in other populations, which corroborates with our data. Furthermore, we suggest the inclusion of the SCL26A4 gene in the investigation of hereditary HL since there was an increase in the frequency of the mutations found, up to 22.7%.
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Affiliation(s)
| | - Carlos Henrique Paiva Grangeiro
- Department of Genetics, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil.,Medical Genetics Service of the University Hospital of the Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Clarissa Gondim Picanço-Albuquerque
- Department of Genetics, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil.,Medical Genetics Service of the University Hospital of the Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Thaís Oliveira Dos Anjos
- Center for Medical Genomics at University Hospital of the Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Greice Andreotti De Molfetta
- Department of Genetics, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil.,Center for Medical Genomics at University Hospital of the Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Wilson Araujo Silva
- Department of Genetics, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil.,Center for Medical Genomics at University Hospital of the Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil.,Regional Blood Center of Ribeirão Preto (FUNDHERP) of the Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Victor Evangelista de Faria Ferraz
- Department of Genetics, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil. .,Medical Genetics Service of the University Hospital of the Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil. .,Center for Medical Genomics at University Hospital of the Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, 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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Intra-familial phenotypic variability in a Moroccan family with hearing loss and palmoplantar keratoderma (PPK). Curr Res Transl Med 2016; 64:61-4. [PMID: 27316387 DOI: 10.1016/j.retram.2016.01.011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Accepted: 01/27/2016] [Indexed: 01/03/2023]
Abstract
Mutations in the GJB2 gene encoding connexin 26 are the main cause of hereditary hearing impairment. These mutations generate mainly autosomal recessive and rarely autosomal dominant deafness. Dominant mutations in GJB2 can be responsible for isolated deafness as well as syndromic hearing loss associated with various skin abnormalities. Until now few papers discuss dominant mutations in the GJB2 gene. In this work we report a rare case about a Moroccan family with a compound heterozygous mutation (the dominant p.R75Q and the recessive c.35delG alleles) in the GJB2 gene with intra-familial phenotypic variability. This study reinforces the involvement of p.R75Q mutation of GJB2 in syndromic deafness associated with dermatological diseases the palmoplantar keratoderma.
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Pavithra A, Selvakumari M, Nityaa V, Sharanya N, Ramakrishnan R, Narasimhan M, Srisailapathy CRS. Autosomal dominant hearing loss resulting from p.R75Q mutation in the GJB2 gene: nonsyndromic presentation in a South Indian family. Ann Hum Genet 2014; 79:76-82. [PMID: 25393658 DOI: 10.1111/ahg.12086] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2014] [Accepted: 09/19/2014] [Indexed: 11/26/2022]
Abstract
Mutations in the GJB2 gene encoding the gap junction protein Connexin 26 have been associated with autosomal recessive as well as dominant nonsyndromic hearing loss. Owing to the involvement of connexins in skin homeostasis, GJB2 mutations have also been associated with syndromic forms of hearing loss showing various skin manifestations. We report an assortatively mating hearing impaired family of south Indian origin with three affected members spread over two generations, having p.R75Q mutation in the GJB2 gene in the heterozygous condition. The inheritance pattern was autosomal dominant with mother and son being affected. Dermatological and histopathologic examinations showed absence of palmoplantar keratoderma. To the best of our knowledge, this is the first report from India on p.R75Q mutation in the GJB2 gene with nonsyndromic hearing loss.
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Affiliation(s)
- Amritkumar Pavithra
- Department of Genetics, Dr. ALM Post Graduate Institute of Basic Medical Sciences, University of Madras, Taramani Campus, Chennai, India
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Frequency of GJB2 and del(GJB6-D13S1830) mutations among an Ecuadorian mestizo population. Int J Pediatr Otorhinolaryngol 2014; 78:1648-54. [PMID: 25085072 DOI: 10.1016/j.ijporl.2014.07.014] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/10/2014] [Revised: 07/08/2014] [Accepted: 07/12/2014] [Indexed: 12/11/2022]
Abstract
OBJECTIVE The frequency of GJB2 mutations and of the del(GJB6-D13S1830) mutation has not been established among the Ecuadorian mestizo population diagnosed with autosomal recessive non-syndromic hearing loss. A genetic analysis was therefore designed in order to do so. METHODS The sample population included 111 subjects of which 26 were autosomal recessive non-syndromic hearing loss probands. Posterior to PCR amplification, sequencing analysis of exon 2 was used for mutational detection of the GJB2 gene; a multiplex PCR method was used for detection of the del(GJB6-D13S1830) mutation. The ratio of subjects with a certain state of the mutation (heterozygous/homozygous) is expressed as a percentage and significant differences between probands and controls were calculated using Fisher's exact test; P<0.05 was considered significant. RESULTS A total of 104 mutations belonging to 8 allelic variations were identified. The most common being the V27I (58.9%); however, as this variation is a non-pathogenic polymorphism, Q7X, with a total of 19 mutated alleles, was the most frequent mutation (18.3%). The V27I polymorphism was the only variation distributed homogenously among probands and controls (P=0.351). Based on physical analyses of multiple patients we confirm that Q7X causes a non-syndromic form of hearing loss and propose that it is a possible predominant mutation in the Ecuadorian population. CONCLUSIONS This is the first study of its kind among the Ecuadorian population and a preliminary step in establishing GJB2 and del(GJB6-D13S1830) mutational frequencies in this population; it is also the first to report of such a high frequency of the Q7X mutation. The data presented here brings Ecuador a step closer to providing more efficient treatment for a broader number of patients; additionally, it contributes to a better understanding of the relationship between autosomal recessive non-syndromic hearing loss and mutations on the GJB2 gene.
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Abstract
This is a guide for fieldwork in Population Medical Genetics research projects. Data collection, handling, and analysis from large pedigrees require the use of specific tools and methods not widely familiar to human geneticists, unfortunately leading to ineffective graphic pedigrees. Initially, the objective of the pedigree must be decided, and the available information sources need to be identified and validated. Data collection and recording by the tabulated method is advocated, and the involved techniques are presented. Genealogical and personal information are the two main components of pedigree data. While the latter is unique to each investigation project, the former is solely represented by gametic links between persons. The triad of a given pedigree member and its two parents constitutes the building unit of a genealogy. Likewise, three ID numbers representing those three elements of the triad is the record field required for any pedigree analysis. Pedigree construction, as well as pedigree and population data analysis, varies according to the pre-established objectives, the existing information, and the available resources.
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Affiliation(s)
- Fernando A Poletta
- Estudio Colaborativo Latinoamericano de Malformaciones Congénitas, Instituto Nacional de Genética Médica Populacional, Rio de Janeiro, RJ, Brazil . ; Latin American Collaborative Study of Congenital Malformations, Center for Medical Education and Clinical Research, Buenos Aires, Argentina
| | - Ieda M Orioli
- Estudio Colaborativo Latinoamericano de Malformaciones Congénitas, Instituto Nacional de Genética Médica Populacional, Rio de Janeiro, RJ, Brazil . ; Departamento de Genética, Instituto de Biologia, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Eduardo E Castilla
- Estudio Colaborativo Latinoamericano de Malformaciones Congénitas, Instituto Nacional de Genética Médica Populacional, Rio de Janeiro, RJ, Brazil . ; Latin American Collaborative Study of Congenital Malformations, Center for Medical Education and Clinical Research, Buenos Aires, Argentina
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11
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Chen G, Liu J, Dong J, Li J, Fu S. GJB2 mutations are rare in probands with hearing loss in Chinese assortative mating families. Int J Pediatr Otorhinolaryngol 2014; 78:244-7. [PMID: 24359977 DOI: 10.1016/j.ijporl.2013.11.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/04/2013] [Revised: 10/09/2013] [Accepted: 11/16/2013] [Indexed: 10/25/2022]
Abstract
OBJECTIVE GJB2 mutation is recognized as the prevalent causes of non-syndromic hearing loss (NSHL) worldwide. However, the mutation profiles of GJB2 are rarely reported in deafness probands of the assortative mating family. Therefore, this study aimed to characterize the frequencies of GJB2 mutations in probands with hearing loss in the assortative mating family in Hubei province, Central China. METHODS Genomic DNA was extracted from blood samples of 29 probands with hearing loss. The target fragments were amplified by polymerase chain reaction (PCR) and subjected to sequencing to identify sequence variations. RESULTS None of 29 probands harbored homozygous mutation in GJB2, while GJB2 heterozygous mutations c.134G>A, c.139G>T, and a deletion c.235delC were identified in three probands, respectively. CONCLUSION GJB2 mutations are rare in Chinese probands of assortative mating families. Screening for responsible genes other than GJB2 is necessary for NSHL in these probands.
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Affiliation(s)
- Guanming Chen
- Department of Otolarygology, Tongji Hospital, Tongji Medical College of Huazhong University of Science and Technology, Wuhan, China
| | - Jing Liu
- Department of Medical Genetics, Tongji Medical College of Huazhong University of Science and Technology, 13 Hangkong Road, 430030 Wuhan, China
| | - Jiashu Dong
- Rehabilitation Research Center for Deaf Children, Wuhan, China
| | - Jiaxin Li
- Department of Pediatrics, Huai'an First People's Hospital, Nanjing Medical University, 6 Beijing Road West, Huai'an 223300, China.
| | - Siqing Fu
- Department of Medical Genetics, Tongji Medical College of Huazhong University of Science and Technology, 13 Hangkong Road, 430030 Wuhan, China.
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