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Alkowari MK, Vozzi D, Bhagat S, Krishnamoorthy N, Morgan A, Hayder Y, Logendra B, Najjar N, Gandin I, Gasparini P, Badii R, Girotto G, Abdulhadi K. Targeted sequencing identifies novel variants involved in autosomal recessive hereditary hearing loss in Qatari families. Mutat Res 2017; 800-802:29-36. [PMID: 28501645 DOI: 10.1016/j.mrfmmm.2017.05.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2017] [Revised: 04/11/2017] [Accepted: 05/03/2017] [Indexed: 06/07/2023]
Abstract
Hereditary hearing loss is characterized by a very high genetic heterogeneity. In the Qatari population the role of GJB2, the worldwide HHL major player, seems to be quite limited compared to Caucasian populations. In this study we analysed 18 Qatari families affected by non-syndromic hearing loss using a targeted sequencing approach that allowed us to analyse 81 genes simultaneously. Thanks to this approach, 50% of these families (9 out of 18) resulted positive for the presence of likely causative alleles in 6 different genes: CDH23, MYO6, GJB6, OTOF, TMC1 and OTOA. In particular, 4 novel alleles were detected while the remaining ones were already described to be associated to HHL in other ethnic groups. Molecular modelling has been used to further investigate the role of novel alleles identified in CDH23 and TMC1 genes demonstrating their crucial role in Ca2+ binding and therefore possible functional role in proteins. Present study showed that an accurate molecular diagnosis based on next generation sequencing technologies might largely improve molecular diagnostics outcome leading to benefits for both genetic counseling and definition of recurrence risk.
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Affiliation(s)
- Moza K Alkowari
- Division of Experimental Genetics, Sidra Medical and Research Centre, Doha, Qatar
| | - Diego Vozzi
- Medical Genetics, Institute for Maternal and Child Health - IRCCS "Burlo Garofolo", Trieste, Italy
| | | | - Navaneethakrishnan Krishnamoorthy
- Division of Experimental Genetics, Sidra Medical and Research Centre, Doha, Qatar; Heart Science Centre, National Heart and Lung Institute, Imperial College London, United Kingdom
| | - Anna Morgan
- Medical Genetics, Institute for Maternal and Child Health - IRCCS "Burlo Garofolo", Trieste, Italy; Medical Sciences, Chirurgical and Health Department, University of Trieste, Trieste, Italy
| | | | | | | | - Ilaria Gandin
- Medical Genetics, Institute for Maternal and Child Health - IRCCS "Burlo Garofolo", Trieste, Italy
| | - Paolo Gasparini
- Medical Genetics, Institute for Maternal and Child Health - IRCCS "Burlo Garofolo", Trieste, Italy; Medical Sciences, Chirurgical and Health Department, University of Trieste, Trieste, Italy
| | - Ramin Badii
- Molecular Genetics Laboratory, HMC, Doha, Qatar
| | - Giorgia Girotto
- Medical Genetics, Institute for Maternal and Child Health - IRCCS "Burlo Garofolo", Trieste, Italy; Medical Sciences, Chirurgical and Health Department, University of Trieste, Trieste, Italy.
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Bliznetz EA, Lalayants MR, Markova TG, Balanovsky OP, Balanovska EV, Skhalyakho RA, Pocheshkhova EA, Nikitina NV, Voronin SV, Kudryashova EK, Glotov OS, Polyakov AV. Update of the GJB2/DFNB1 mutation spectrum in Russia: a founder Ingush mutation del(GJB2-D13S175) is the most frequent among other large deletions. J Hum Genet 2017; 62:789-795. [PMID: 28405014 PMCID: PMC5584515 DOI: 10.1038/jhg.2017.42] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2016] [Revised: 03/05/2017] [Accepted: 03/05/2017] [Indexed: 11/09/2022]
Abstract
Although mutations in the GJB2 gene sequence make up the majority of variants causing autosomal-recessive non-syndromic hearing loss, few large deletions have been shown to contribute to DFNB1 deafness. Currently, genetic testing for DFNB1 hearing loss includes GJB2 sequencing and DFNB1 deletion analysis for two common large deletions, del(GJB6-D13S1830) and del(GJB6-D13S1854). Here, we report frequency in Russia, clinical significance and evolutionary origins of a 101 kb deletion, del(GJB2-D13S175), recently identified by us. In multiethnic cohort of 1104 unrelated hearing loss patients with biallelic mutations at the DFNB1 locus, the del(GJB2-D13S175) allele frequency of up to 0.5% (11/2208) was determined and this allele was shown to be predominantly associated with profound sensorineural hearing loss. Additionally, eight previously unpublished GJB2 mutations were described in this study. All patients carrying del(GJB2-D13S175) were of the Ingush ancestry. Among normal hearing individuals, del(GJB2-D13S175) was observed in Russian Republic of Ingushetia with a carrier rate of ~1% (2/241). Analysis of haplotypes associated with the deletion revealed a common founder in the Ingushes, with age of the deletion being ~3000 years old. Since del(GJB2-D13S175) was missed by standard methods of GJB2 analysis, del(GJB2-D13S175) detection has been added to our routine testing strategy for DFNB1 hearing loss.
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Affiliation(s)
- Elena A Bliznetz
- The Federal Agency for Scientific Organizations, Federal State Budgetary Institution, Research Centre for Medical Genetics, Moscow, Russia
| | - Maria R Lalayants
- Federal Medical and Biological Agency, Federal State-Funded Institution of Science, National Research Center for Audiology and Hearing Rehabilitation, Moscow, Russia
| | - Tatiana G Markova
- Federal Medical and Biological Agency, Federal State-Funded Institution of Science, National Research Center for Audiology and Hearing Rehabilitation, Moscow, Russia
| | - Oleg P Balanovsky
- The Federal Agency for Scientific Organizations, Federal State Budgetary Institution, Research Centre for Medical Genetics, Moscow, Russia
- The Russian Academy of Sciences, Federal State-Funded Institution of Science, Vavilov Institute of General Genetics, Moscow, Russia
| | - Elena V Balanovska
- The Federal Agency for Scientific Organizations, Federal State Budgetary Institution, Research Centre for Medical Genetics, Moscow, Russia
| | - Roza A Skhalyakho
- The Federal Agency for Scientific Organizations, Federal State Budgetary Institution, Research Centre for Medical Genetics, Moscow, Russia
- The Russian Academy of Sciences, Federal State-Funded Institution of Science, Vavilov Institute of General Genetics, Moscow, Russia
| | - Elvira A Pocheshkhova
- The Ministry of Health, Federal State-Funded Educational Institution of Higher Education, Kuban State Medical University, Krasnodar, Russia
| | - Natalya V Nikitina
- The Ministry of Health, State Budgetary Healthcare Institution, Clinical-Diagnostic Center of Mother and Child Health Protection, Yekaterinburg, Russia
| | - Sergey V Voronin
- State Autonomous Healthcare Institution, Regional Clinical Center of Specialized Medical Care, Vladivostok, Russia
| | - Elena K Kudryashova
- The Ministry of Health, State Budgetary Healthcare Institution, Leningrad Regional Clinical Hospital, Saint Petersburg, Russia
| | - Oleg S Glotov
- Federal State Budgetary Educational Institution of Higher Education, Saint Petersburg University, Saint Petersburg, Russia
| | - Alexander V Polyakov
- The Federal Agency for Scientific Organizations, Federal State Budgetary Institution, Research Centre for Medical Genetics, Moscow, Russia
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Pshennikova VG, Barashkov NA, Solovyev AV, Romanov GP, Diakonov EE, Sazonov NN, Morozov IV, Bondar AA, Posukh OL, Dzhemileva LU, Khusnutdinova EK, Tomsky MI, Fedorova SA. Analysis of GJB6 (Сx30) and GJB3 (Сx31) genes in deaf patients with monoallelic mutations in GJB2 (Сx26) gene in the Sakha Republic (Yakutia). RUSS J GENET+ 2017. [DOI: 10.1134/s1022795417030103] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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54
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Bliznetz EA, Kanivets IV, Polyakov AV. DNA copy number analysis of the DFNB1 hereditary hearing loss locus. RUSS J GENET+ 2017. [DOI: 10.1134/s1022795417050027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Rudman JR, Kabahuma RI, Bressler SE, Feng Y, Blanton SH, Yan D, Liu XZ. The genetic basis of deafness in populations of African descent. J Genet Genomics 2017; 44:285-294. [PMID: 28642064 DOI: 10.1016/j.jgg.2017.03.008] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Revised: 02/03/2017] [Accepted: 03/24/2017] [Indexed: 11/24/2022]
Abstract
Hearing loss is the most common sensorineural disorder worldwide and is associated with more than 1000 mutations in more than 90 genes. While mutations in genes such as GJB2 (gap-junction protein β 2) and GJB6 (gap-junction protein β 6) are highly prevalent in Caucasian, Asian, and Middle Eastern populations, they are rare in both native African populations and those of African descent. The objective of this paper is to review the current knowledge regarding the epidemiology and genetics of hearing loss in African populations with a focus on native sub-Saharan African populations. Environmental etiologies related to poor access to healthcare and perinatal care account for the majority of cases. Syndromic etiologies including Waardenburg, Pendred and Usher syndromes are uncommon causes of hearing loss in these populations. Of the non-syndromic causes, common mutations in GJB2 and GJB6 are rarely implicated in populations of African descent. Recent use of next-generation sequencing (NGS) has identified several candidate deafness genes in African populations from Nigeria and South Africa that are unique when compared to common causative mutations worldwide. Researchers also recently described a dominant mutation in MYO3a in an African American family with non-syndromic hearing loss. The use of NGS and specialized panels will aid in identifying rare and novel mutations in a more cost- and time-effective manner. The identification of common hearing loss mutations in indigenous African populations will pave the way for translation into genetic deafness research in populations of African descent worldwide.
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Affiliation(s)
- Jason R Rudman
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Rosemary I Kabahuma
- Department of Otorhinolaryngology, Steve Biko Academic Hospital, University of Pretoria, Pretoria 0001, South Africa.
| | - Sara E Bressler
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Yong Feng
- Department of Otolaryngology, Xiangya Hospital, Central South University, Changsha 410008, China
| | - Susan H Blanton
- 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; John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Denise Yan
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Xue-Zhong Liu
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, FL 33136, USA; Department of Otolaryngology, Xiangya Hospital, Central South University, Changsha 410008, China; Dr. John T. Macdonald Foundation Department of Human Genetics, University of Miami Miller School of Medicine, Miami, FL 33136, USA; John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, FL 33136, USA.
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Sommen M, Wuyts W, Van Camp G. Molecular diagnostics for hereditary hearing loss in children. Expert Rev Mol Diagn 2017; 17:751-760. [PMID: 28593790 DOI: 10.1080/14737159.2017.1340834] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
INTRODUCTION Hearing loss (HL) is the most common birth defect in industrialized countries with far-reaching social, psychological and cognitive implications. It is an extremely heterogeneous disease, complicating molecular testing. The introduction of next-generation sequencing (NGS) has resulted in great progress in diagnostics allowing to study all known HL genes in a single assay. The diagnostic yield is currently still limited, but has the potential to increase substantially. Areas covered: In this review the utility of NGS and the problems for comprehensive molecular testing for HL are evaluated and discussed. Expert commentary: Different publications have proven the appropriateness of NGS for molecular testing of heterogeneous diseases such as HL. However, several problems still exist, such as pseudogenic background of some genes and problematic copy number variant analysis on targeted NGS data. Another main challenge for the future will be the establishment of population specific mutation-spectra to achieve accurate personalized comprehensive molecular testing for HL.
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Affiliation(s)
- Manou Sommen
- a Center of Medical Genetics , University of Antwerp & Antwerp University Hospital , Antwerp , Belgium
| | - Wim Wuyts
- a Center of Medical Genetics , University of Antwerp & Antwerp University Hospital , Antwerp , Belgium
| | - Guy Van Camp
- a Center of Medical Genetics , University of Antwerp & Antwerp University Hospital , Antwerp , Belgium
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Parzefall T, Lucas T, Koenighofer M, Ramsebner R, Frohne A, Czeiger S, Baumgartner WD, Schoefer C, Gstoettner W, Frei K. The role of alternative GJB2 transcription in screening for neonatal sensorineural deafness in Austria. Acta Otolaryngol 2017; 137:356-360. [PMID: 27827000 DOI: 10.1080/00016489.2016.1249946] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
CONCLUSION Alterations within a novel putative Exon 1a within the gap junction beta 2 (GJB2) gene may play a role in the development of genetic hearing impairment in Austria. OBJECTIVES Mutations in the GJB2 gene are the most common cause of hereditary sensorineural deafness. Genome-wide screening for alternative transcriptional start sites in the human genome has revealed the presence of an additional GJB2 exon (E1a). This study tested the hypothesis of whether alternative GJB2 transcription involving E1a may play a role in the development of congenital sensorineural deafness in Austria. METHODS GJB2 E1a and flanking regions were sequenced in randomized normal hearing control subjects and three different patient groups with non-syndromic hearing impairment (NSHI), and bioinformatic analysis was performed. Statistical analysis of disease association was carried out using the Cochran-Armitage test for trend. RESULTS A single change 2410 bp proximal to the translational start site (c.-2410T > C, rs7994748, NM_004004.5:c.-23 + 792T > C) was found to be significantly associated with the common c.35delG GJB2 mutation (p = .009). c.35delG in combination with c.-2410CC occurred at a 6.9-fold increased frequency compared to the control group. Additionally, one patient with idiopathic congenital hearing loss was found to be homozygous c.-2410CC.
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Affiliation(s)
- Thomas Parzefall
- Department of Otorhinolaryngology, Medical University of Vienna, Austria
| | - Trevor Lucas
- Department for Cell- and Developmental Biology, Medical University of Vienna, Austria
| | - Martin Koenighofer
- Department of Otorhinolaryngology, Medical University of Vienna, Austria
| | - Reinhard Ramsebner
- Department of Otorhinolaryngology, Medical University of Vienna, Austria
| | - Alexandra Frohne
- Department for Cell- and Developmental Biology, Medical University of Vienna, Austria
| | - Shelly Czeiger
- Department for Cell- and Developmental Biology, Medical University of Vienna, Austria
| | | | - Christian Schoefer
- Department for Cell- and Developmental Biology, Medical University of Vienna, Austria
| | | | - Klemens Frei
- Department of Otorhinolaryngology, Medical University of Vienna, Austria
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Yan D, Xiang G, Chai X, Qing J, Shang H, Zou B, Mittal R, Shen J, Smith RJH, Fan YS, Blanton SH, Tekin M, Morton C, Xing W, Cheng J, Liu XZ. Screening of deafness-causing DNA variants that are common in patients of European ancestry using a microarray-based approach. PLoS One 2017; 12:e0169219. [PMID: 28273078 PMCID: PMC5342170 DOI: 10.1371/journal.pone.0169219] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Accepted: 12/04/2016] [Indexed: 12/12/2022] Open
Abstract
The unparalleled heterogeneity in genetic causes of hearing loss along with remarkable differences in prevalence of causative variants among ethnic groups makes single gene tests technically inefficient. Although hundreds of genes have been reported to be associated with nonsyndromic hearing loss (NSHL), GJB2, GJB6, SLC26A4, and mitochondrial (mt) MT-RNR1 and MTTS are the major contributors. In order to provide a faster, more comprehensive and cost effective assay, we constructed a DNA fluidic array, CapitalBioMiamiOtoArray, for the detection of sequence variants in five genes that are common in most populations of European descent. They consist of c.35delG, p.W44C, p.L90P, c.167delT (GJB2); 309kb deletion (GJB6); p.L236P, p.T416P (SLC26A4); and m.1555A>G, m.7444G>A (mtDNA). We have validated our hearing loss array by analyzing a total of 160 DNAs samples. Our results show 100% concordance between the fluidic array biochip-based approach and the established Sanger sequencing method, thus proving its robustness and reliability at a relatively low cost.
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Affiliation(s)
- Denise Yan
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, Florida, United States of America
| | - Guangxin Xiang
- National Engineering Research Center for Beijing Biochip Technology, Beijing, China
| | - Xingping Chai
- National Engineering Research Center for Beijing Biochip Technology, Beijing, China
- Tsinghua University School of Medicine, Beijing, China
| | - Jie Qing
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, Florida, United States of America
| | - Haiqiong Shang
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, Florida, United States of America
| | - Bing Zou
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, Florida, United States of America
| | - Rahul Mittal
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, Florida, United States of America
| | - Jun Shen
- Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, United States of America
- Laboratory for Molecular Medicine, Partners Personalized Medicine, Cambridge, Massachusetts, United States of America
| | - Richard J. H. Smith
- Department of Otolaryngology - Head and Neck Surgery, Carver College of Medicine, University of Iowa, Iowa City, Iowa, United States of America
| | - Yao-Shan Fan
- Department of Pathology, University of Miami Miller School of Medicine, Miami, Florida, United States of America
- Dr. John T. Macdonald Department of Human Genetics and John P.Hussman Institute for Human Genetics, University of Miami Miller School of Medicine, Miami, Florida, United States of America
| | - Susan H. Blanton
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, Florida, United States of America
- Department of Pathology, University of Miami Miller School of Medicine, Miami, Florida, United States of America
| | - Mustafa Tekin
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, Florida, United States of America
- Department of Pathology, University of Miami Miller School of Medicine, Miami, Florida, United States of America
| | - Cynthia Morton
- Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, United States of America
- Department of Obstetrics, Gynecology and Reproductive Biology, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, United States of America
- Division of Evolution and Genomic Science, School of Biological Sciences, Manchester Academic Health Science Center, University of Manchester, United Kingdom
| | - Wanli Xing
- National Engineering Research Center for Beijing Biochip Technology, Beijing, China
- Tsinghua University School of Medicine, Beijing, China
| | - Jing Cheng
- National Engineering Research Center for Beijing Biochip Technology, Beijing, China
- Tsinghua University School of Medicine, Beijing, China
| | - Xue Zhong Liu
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, Florida, United States of America
- Tsinghua University School of Medicine, Beijing, China
- Dr. John T. Macdonald Department of Human Genetics and John P.Hussman Institute for Human Genetics, University of Miami Miller School of Medicine, Miami, Florida, United States of America
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First report of prevalence c.IVS1+1G>A and del (GJB6-13S1854) mutations in Syrian families with non-syndromic sensorineural hearing loss. Int J Pediatr Otorhinolaryngol 2017; 92:82-87. [PMID: 28012540 DOI: 10.1016/j.ijporl.2016.11.015] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/17/2016] [Revised: 11/13/2016] [Accepted: 11/14/2016] [Indexed: 11/23/2022]
Abstract
OBJECTIVE Mutations in GJB2 and GJB6 genes are a frequent cause of congenital non-syndromic hearing loss (NSHL). Mutational screening has usually focused on coding region of GJB2 gene. A few studies have been conducted on the non-coding region and exon 1. c.IVS1+1G>A (a splice site mutation in GJB2 gene have been detected as disruptive mutation. Del (GJB6 D13S1830) is found in many populations, but del (GJB6 D13S1854) is reported from a few restricted countries. This study was carried out to investigate the prevalence of splice site mutation c.IVS1+1G>A and two common deletions in GJB6 gene as the genetic etiology of hearing impairment in 70 Syrian families. METHODS The frequency of the c.IVS1+1G>A mutation and two deletions were determined by PCR-RFLP and A multiplex PCR assay. RESULT Our results showed a high prevalence of IVS1+1G>A mutation (20%) and del(GJB6-D13S1854) (15.7%) in deaf families. The homozygous genotype (c.IVS1+1G>A/c.IVS1+1G>A) was observed in one family and the compound heterozygous genotypes (c.35delG/c.IVS1+1G>A) and (c.IVS1+1G>A/V153I) were observed in 7 families and one family respectively. Also, the heterozygous state (c.IVS1+1G>A/unknown) was detected in 5 families. The study of del((GJB6-D13S1854) was showed a compound heterozygous genotype del((GJB6-D13S1854)/c.IVS1+1G>A) in the same families (5 families) having heterozygous genotype of c.IVS1+1G>A mutation. Also, del(GJB6-D13S1854) is combined with c.35delG mutation in 2 families and it was observed in the heterozygous state del(GJB6-D13S1854)/unknown) in 4 families. In contrast, the del(GJB6-D13S1830) described in many population was absent in our patients. CONCLUSION Our findings indicate to significant contribution of the splice site mutation and del(GJB6-D13S1854) in our deaf families and these mutations were important causes of hearing impairment.
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Alves RM, da Silva Costa SM, do Amôr Divino Miranda PM, Ramos PZ, Marconi TG, Santos Oliveira G, Castilho AM, Sartorato EL. Analysis of mitochondrial alterations in Brazilian patients with sensorineural hearing loss using MALDI-TOF mass spectrometry. BMC MEDICAL GENETICS 2016; 17:41. [PMID: 27230773 PMCID: PMC4880863 DOI: 10.1186/s12881-016-0303-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 08/25/2015] [Accepted: 05/20/2016] [Indexed: 02/06/2023]
Abstract
BACKGROUND Mutations in the mitochondrial DNA (mtDNA) have been associated with aminoglycoside-induced and nonsyndromic deafness in different populations. In the present study, we investigated the contribution of mutations in mitochondrial genes to the etiology of hearing loss in a Brazilian sample. METHODS Using mass spectrometry genotyping technology, combined with direct sequencing, 50 alterations previously described in 14 mitochondrial genes were screened in 152 patients with sensorineural hearing loss and in104 normal hearing controls. RESULTS Fifteen known mitochondrial alterations were detected (G709A, A735G, A827G, G988A, A1555G, T4363C, T5628C, T5655C, G5821A, C7462T, G8363A, T10454C, G12236A, T1291C, G15927A). Pathogenic mutations in MT-RNR1 and MT-TK genes were detected in 3 % (5/152) of the patients with hearing loss. CONCLUSIONS This study contributed to show the spectrum of mitochondrial variants in Brazilian patients with hearing loss. Frequency of A1555G was relatively high (2.6 %), indicating that this mutation is an important cause of hearing loss in our population. This work reports for the first time the investigation and the detection of the tRNA(Lys) G8363A mutation in Brazilian patients with maternally inherited sensorineural hearing loss.
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Affiliation(s)
- Rogério Marins Alves
- Center for Molecular and Genetic Engineering (CBMEG), University of Campinas (UNICAMP), Cidade Universitária Zeferino Vaz, Avenida Cândido Rondon 400, PO Box 6010, 13083-875, Campinas, São Paulo, Brazil
| | - Sueli Matilde da Silva Costa
- Center for Molecular and Genetic Engineering (CBMEG), University of Campinas (UNICAMP), Cidade Universitária Zeferino Vaz, Avenida Cândido Rondon 400, PO Box 6010, 13083-875, Campinas, São Paulo, Brazil
| | - Paulo Mauricio do Amôr Divino Miranda
- Center for Molecular and Genetic Engineering (CBMEG), University of Campinas (UNICAMP), Cidade Universitária Zeferino Vaz, Avenida Cândido Rondon 400, PO Box 6010, 13083-875, Campinas, São Paulo, Brazil
| | - Priscila Zonzini Ramos
- Center for Molecular and Genetic Engineering (CBMEG), University of Campinas (UNICAMP), Cidade Universitária Zeferino Vaz, Avenida Cândido Rondon 400, PO Box 6010, 13083-875, Campinas, São Paulo, Brazil
| | - Thiago Gibbin Marconi
- Center for Molecular and Genetic Engineering (CBMEG), University of Campinas (UNICAMP), Cidade Universitária Zeferino Vaz, Avenida Cândido Rondon 400, PO Box 6010, 13083-875, Campinas, São Paulo, Brazil
| | - Gisele Santos Oliveira
- Center for Molecular and Genetic Engineering (CBMEG), University of Campinas (UNICAMP), Cidade Universitária Zeferino Vaz, Avenida Cândido Rondon 400, PO Box 6010, 13083-875, Campinas, São Paulo, Brazil
| | - Arthur Menino Castilho
- Otology, Audiology and Implantable Ear Prostheses, University of Campinas (UNICAMP), Cidade Universitária Zeferino Vaz, Campinas, São Paulo, Brazil
| | - Edi Lúcia Sartorato
- Center for Molecular and Genetic Engineering (CBMEG), University of Campinas (UNICAMP), Cidade Universitária Zeferino Vaz, Avenida Cândido Rondon 400, PO Box 6010, 13083-875, Campinas, São Paulo, Brazil.
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Carvalho GMD, Ramos PZ, Castilho AM, Guimarães AC, Sartorato EL. Molecular study of patients with auditory neuropathy. Mol Med Rep 2016; 14:481-90. [PMID: 27177047 DOI: 10.3892/mmr.2016.5226] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Accepted: 01/20/2016] [Indexed: 11/05/2022] Open
Abstract
Auditory neuropathy is a type of hearing loss that constitutes a change in the conduct of the auditory stimulus by the involvement of inner hair cells or auditory nerve synapses. It is characterized by the absence or alteration of waves in the examination of brainstem auditory evoked potentials, with otoacoustic and/or cochlear microphonic issues. At present, four loci associated with non‑syndromic auditory neuropathy have been mapped: Autosomal recessive deafness‑9 [DFNB9; the otoferlin (OTOF) gene] and autosomal recessive deafness‑59 [DFNB59; the pejvakin (PJVK) gene], associated with autosomal recessive inheritance; the autosomal dominant auditory neuropathy gene [AUNA1; the diaphanous‑3 (DIAPH3) gene]; and AUNX1, linked to chromosome X. Furthermore, mutations of connexin 26 [the gap junction β2 (GJB2) gene] have also been associated with the disease. OTOF gene mutations exert a significant role in auditory neuropathy. In excess of 80 pathogenic mutations have been identified in individuals with non‑syndromic deafness in populations of different origins, with an emphasis on the p.Q829X mutation, which was found in ~3% of cases of deafness in the Spanish population. The identification of genetic alterations responsible for auditory neuropathy is one of the challenges contributing to understand the molecular bases of the different phenotypes of hearing loss. Thus, the present study aimed to investigate molecular changes in the OTOF gene in patients with auditory neuropathy, and to develop a DNA chip for the molecular diagnosis of auditory neuropathy using mass spectrometry for genotyping. Genetic alterations were investigated in 47 patients with hearing loss and clinical diagnosis of auditory neuropathy, and the c.35delG mutation in the GJB2 gene was identified in three homozygous patients, and the heterozygous parents of one of these cases. Additionally, OTOF gene mutations were tracked by complete sequencing of 48 exons, although these results are still preliminary. Studying the genetic basis of auditory neuropathy is of utmost importance for obtaining a differential diagnosis, developing more specific treatments and more accurate genetic counseling.
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Affiliation(s)
- Guilherme Machado De Carvalho
- Otology, Audiology and Implantable Ear Prostheses, Ear, Nose, Throat and Head and Neck Surgery Department, State University of Campinas (UNICAMP), São Paulo 13081‑970, Brazil
| | - Priscila Zonzini Ramos
- Human Molecular Genetics Laboratory, Molecular Biology and Genetic Engineering Center‑CBMEG, State University of Campinas (UNICAMP), São Paulo 13081‑970, Brazil
| | - Arthur Menino Castilho
- Otology, Audiology and Implantable Ear Prostheses, Ear, Nose, Throat and Head and Neck Surgery Department, State University of Campinas (UNICAMP), São Paulo 13081‑970, Brazil
| | - Alexandre Caixeta Guimarães
- Otology, Audiology and Implantable Ear Prostheses, Ear, Nose, Throat and Head and Neck Surgery Department, State University of Campinas (UNICAMP), São Paulo 13081‑970, Brazil
| | - Edi Lúcia Sartorato
- Human Molecular Genetics Laboratory, Molecular Biology and Genetic Engineering Center‑CBMEG, State University of Campinas (UNICAMP), São Paulo 13081‑970, Brazil
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Mikstiene V, Jakaitiene A, Byckova J, Gradauskiene E, Preiksaitiene E, Burnyte B, Tumiene B, Matuleviciene A, Ambrozaityte L, Uktveryte I, Domarkiene I, Rancelis T, Cimbalistiene L, Lesinskas E, Kucinskas V, Utkus A. The high frequency of GJB2 gene mutation c.313_326del14 suggests its possible origin in ancestors of Lithuanian population. BMC Genet 2016; 17:45. [PMID: 26896187 PMCID: PMC4761217 DOI: 10.1186/s12863-016-0354-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2015] [Accepted: 02/15/2016] [Indexed: 12/30/2022] Open
Abstract
Background Congenital hearing loss (CHL) is diagnosed in 1 – 2 newborns in 1000, genetic factors contribute to two thirds of CHL cases in industrialised countries. Mutations of the GJB2 gene located in the DFNB1 locus (13q11-12) are a major cause of CHL worldwide. The aim of this cross-sectional study was to assess the contribution of the DFNB1 locus containing the GJB2 and GJB6 genes in the development of early onset hearing loss in the affected group of participants, to determine the population-specific mutational profile and DFNB1-related HL burden in Lithuanian population. Methods Clinical data were obtained from a collection of 158 affected participants (146 unrelated probands) with early onset non-syndromic HL. GJB2 and GJB6 gene sequencing and GJB6 gene deletion testing were performed. The data of GJB2 and GJB6 gene sequencing in 98 participants in group of self-reported healthy Lithuanian inhabitants were analysed. Statistic summary, homogeneity tests, and logistic regression analysis were used for the assessment of genotype-phenotype correlation. Results Our findings show 57.5 % of affected participants with two pathogenic GJB2 gene mutations identified. The most prevalent GJB2 mutations were c.35delG, p. (Gly12Valfs*2) (rs80338939) and c.313_326del14, p. (Lys105Glyfs*5) (rs111033253) with allele frequencies 64.7 % and 28.3 % respectively. GJB6 gene mutations were not identified in the affected group of participants. The statistical analysis revealed significant differences between GJB2(−) and GJB2(+) groups in disease severity (p = 0.001), and family history (p = 0.01). The probability of identification of GJB2 mutations in patients with various HL characteristics was estimated. The carrier rate of GJB2 gene mutations – 7.1 % (~1 in 14) was identified in the group of healthy participants and a high frequency of GJB2-related hearing loss was estimated in our population. Discussion The results show a very high proportion of GJB2-positive individuals in the research group affected with sensorineural HL. The allele frequency of c.35delG mutation (64.7 %) is consistent with many previously published studies in groups of affected individuals of Caucasian populations. The high frequency of the c.313_326del14 (28.3 % of pathogenic alleles) mutation in affected group of participants was an unexpected finding in our study suggesting not only a high frequency of carriers of this mutation in our population but also its possible origin in Lithuanian ancestors. The high frequency of carriers of the c.313_326del14 mutation in the entire Lithuanian population is supported by it being identified twice in the ethnic Lithuanian group of healthy participants (a frequency 2.0 % of carriers in the study group). Conclusion Analysis of the allele frequency of GJB2 gene mutations revealed a high proportion of c. 313_326del14 (rs111033253) mutations in the GJB2-positive group suggesting its possible origin in Lithuanian forebears. The high frequency of carriers of GJB2 gene mutations in the group of healthy participants corresponds to the substantial frequency of GJB2-associated HL in Lithuania. The observations of the study indicate the significant contribution of GJB2 gene mutations to the pathogenesis of the disorder in the Lithuanian population and will contribute to introducing principles to predict the characteristics of the disease in patients. Electronic supplementary material The online version of this article (doi:10.1186/s12863-016-0354-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Violeta Mikstiene
- Department of Human and Medical Genetics, Faculty of Medicine, Vilnius University, Vilnius, Lithuania.
| | - Audrone Jakaitiene
- Department of Human and Medical Genetics, Faculty of Medicine, Vilnius University, Vilnius, Lithuania.
| | - Jekaterina Byckova
- Centre of Ear, Nose and Throat Diseases, Vilnius University Hospital Santariskiu clinics, Vilnius, Lithuania.
| | - Egle Gradauskiene
- Centre of Ear, Nose and Throat Diseases, Vilnius University Hospital Santariskiu clinics, Vilnius, Lithuania.
| | - Egle Preiksaitiene
- Department of Human and Medical Genetics, Faculty of Medicine, Vilnius University, Vilnius, Lithuania.
| | - Birute Burnyte
- Department of Human and Medical Genetics, Faculty of Medicine, Vilnius University, Vilnius, Lithuania.
| | - Birute Tumiene
- Department of Human and Medical Genetics, Faculty of Medicine, Vilnius University, Vilnius, Lithuania.
| | - Ausra Matuleviciene
- Department of Human and Medical Genetics, Faculty of Medicine, Vilnius University, Vilnius, Lithuania.
| | - Laima Ambrozaityte
- Department of Human and Medical Genetics, Faculty of Medicine, Vilnius University, Vilnius, Lithuania.
| | - Ingrida Uktveryte
- Department of Human and Medical Genetics, Faculty of Medicine, Vilnius University, Vilnius, Lithuania.
| | - Ingrida Domarkiene
- Department of Human and Medical Genetics, Faculty of Medicine, Vilnius University, Vilnius, Lithuania.
| | - Tautvydas Rancelis
- Department of Human and Medical Genetics, Faculty of Medicine, Vilnius University, Vilnius, Lithuania.
| | - Loreta Cimbalistiene
- Department of Human and Medical Genetics, Faculty of Medicine, Vilnius University, Vilnius, Lithuania.
| | - Eugenijus Lesinskas
- Centre of Ear, Nose and Throat Diseases, Vilnius University Hospital Santariskiu clinics, Vilnius, Lithuania.
| | - Vaidutis Kucinskas
- Department of Human and Medical Genetics, Faculty of Medicine, Vilnius University, Vilnius, Lithuania.
| | - Algirdas Utkus
- Department of Human and Medical Genetics, Faculty of Medicine, Vilnius University, Vilnius, Lithuania.
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Pandey N, Xavier DF, Chatterjee A, Mani RS, Hiremagalore R, Tharakan A, Rajashekhar B, Anand A. Functional Analysis of a Novel Connexin30 Mutation in a Large Family with Hearing Loss, Pesplanus, Ichthyosis, Cutaneous Nodules, and Keratoderma. Ann Hum Genet 2015; 80:11-9. [PMID: 26620415 DOI: 10.1111/ahg.12141] [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: 12/24/2014] [Accepted: 09/11/2015] [Indexed: 11/28/2022]
Abstract
Mutations in the gap-junction gene Cx30 (Connexin30, GJB6) are a known cause of hearing loss. Here, we report our findings on a large multigeneration family in which severe to profound sensorineural hearing impairment is associated with a variety of skin-related anomalies. Genome-wide analysis of the family showed that the locus maps to chromosome region 13ptel-q12.1 and that a novel mutation, p.N54K, in Cx30, cosegregates with the phenotype. Unlike wild-type Cx30, p.N54K Cx30 is predominantly localized in the cytoplasm and does not permit transfer of neurobiotin, suggesting improper cellular localization and abolishment of gap-junction activity.
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Affiliation(s)
- Nishtha Pandey
- Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore, India.,Centre for Human Genetics, Bangalore, India
| | - Dennis F Xavier
- Department of Speech and Hearing, School of Allied Health Sciences, Manipal University, Manipal, India
| | - Arunima Chatterjee
- Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore, India
| | - Ram-Shankar Mani
- Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore, India
| | | | - Ajith Tharakan
- Department of Dermatology, Sree Narayana Institute of Medical Sciences, Cochin, India
| | - B Rajashekhar
- Department of Speech and Hearing, School of Allied Health Sciences, Manipal University, Manipal, India
| | - Anuranjan Anand
- Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore, India
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Abou Tayoun AN, Al Turki SH, Oza AM, Bowser MJ, Hernandez AL, Funke BH, Rehm HL, Amr SS. Improving hearing loss gene testing: a systematic review of gene evidence toward more efficient next-generation sequencing-based diagnostic testing and interpretation. Genet Med 2015; 18:545-53. [PMID: 26562227 DOI: 10.1038/gim.2015.141] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2015] [Accepted: 08/27/2015] [Indexed: 12/11/2022] Open
Abstract
PURPOSE With next generation sequencing technology improvement and cost reductions, it has become technically feasible to sequence a large number of genes in one diagnostic test. This is especially relevant for diseases with large genetic and/or phenotypic heterogeneity, such as hearing loss. However, variant interpretation remains the major bottleneck. This is further exacerbated by the lack in the clinical genetics community of consensus criteria for defining the evidence necessary to include genes on targeted disease panels or in genomic reports, and the consequent risk of reporting variants in genes with no relevance to disease. METHODS We describe a systematic evidence-based approach for assessing gene-disease associations and for curating relevant genes for different disease aspects, including mode of inheritance, phenotypic severity, and mutation spectrum. RESULTS By applying this approach to clinically available hearing loss gene panels with a total of 163 genes, we show that a significant number (45%) of genes lack sufficient evidence of association with disease and thus are expected to increase uncertainty and patient anxiety, in addition to intensifying the interpretation burden. Information about all curated genes is summarized. Our retrospective analysis of 539 hearing loss cases tested by our previous OtoGenomeV2 panel demonstrates the impact of including genes with weak disease association in laboratory wet-bench and interpretation processes. CONCLUSION Our study is, to our knowledge, the first to highlight the urgent need for defining the clinical validity of gene-disease relationships for more efficient and accurate clinical testing and reporting.Genet Med 18 6, 545-553.
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Affiliation(s)
- Ahmad N Abou Tayoun
- Genetics Training Program, Harvard Medical School, Cambridge, Massachusetts, USA.,Laboratory for Molecular Medicine, Partners Healthcare Personalized Medicine, Cambridge, Massachusetts, USA.,Division of Genomic Diagnostics, The Children's Hospital of Philadelphia, The University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA
| | - Saeed H Al Turki
- Genetics Training Program, Harvard Medical School, Cambridge, Massachusetts, USA
| | - Andrea M Oza
- Laboratory for Molecular Medicine, Partners Healthcare Personalized Medicine, Cambridge, Massachusetts, USA
| | - Mark J Bowser
- Laboratory for Molecular Medicine, Partners Healthcare Personalized Medicine, Cambridge, Massachusetts, USA
| | - Amy L Hernandez
- Laboratory for Molecular Medicine, Partners Healthcare Personalized Medicine, Cambridge, Massachusetts, USA
| | - Birgit H Funke
- Laboratory for Molecular Medicine, Partners Healthcare Personalized Medicine, Cambridge, Massachusetts, USA.,Department of Pathology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Heidi L Rehm
- Laboratory for Molecular Medicine, Partners Healthcare Personalized Medicine, Cambridge, Massachusetts, USA.,Department of Pathology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Sami S Amr
- Laboratory for Molecular Medicine, Partners Healthcare Personalized Medicine, Cambridge, Massachusetts, USA.,Department of Pathology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
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Mutation spectrum of autosomal recessive non-syndromic hearing loss in central Iran. Int J Pediatr Otorhinolaryngol 2015; 79:1892-5. [PMID: 26409293 DOI: 10.1016/j.ijporl.2015.08.039] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/17/2015] [Revised: 08/25/2015] [Accepted: 08/27/2015] [Indexed: 01/05/2023]
Abstract
OBJECTIVE To identify the spectrum of mutations in connexin 26 gene and frequency of two deletions in connexin 30 gene in central Iran. METHODS After extraction of DNA from 300 blood samples, connexin 26 gene coding region was amplified using specific primers. PCR products were used for bidirectional sequencing. Multiplex PCR was used for detection of del(GJB6-D13S1830) and del(GJB6-D13S1854) in the GJB6 gene. RESULTS Eighteen different mutations including two novel variants in GJB2 gene were detected. The GJB2 mutations were observed in 23.3% of all the subjects. In addition, none of the deaf patients carried the del(GJB6-D13S1830) and del(GJB6-D13S1854) in the GJB6 gene. The 35delG mutation was the most common mutation, accounting for 32.65% of the mutant alleles. CONCLUSION The present study indicates that mutations in the GJB2 gene particularly 35delG are important causes for ARNSHL. 60% of the patients were heterozygous carriers. Thus, further investigation is needed to detect the genetic cause of hearing loss in patients with mono allelic mutations in the coding region of GJB2.
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66
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Tayoun ANA, Mason-Suares H, Frisella AL, Bowser M, Duffy E, Mahanta L, Funke B, Rehm HL, Amr SS. Targeted Droplet-Digital PCR as a Tool for Novel Deletion Discovery at the DFNB1 Locus. Hum Mutat 2015; 37:119-26. [DOI: 10.1002/humu.22912] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2015] [Accepted: 09/21/2015] [Indexed: 11/09/2022]
Affiliation(s)
- Ahmad N. Abou Tayoun
- Harvard Medical School Genetics Training Program; Harvard; Cambridge MA
- Laboratory for Molecular Medicine; Partners Healthcare Personalized Medicine; Cambridge MA
- Division of Genomic Diagnostics; The Children's Hospital of Philadelphia; The University of Pennsylvania Perelman School of Medicine; PA
| | - Heather Mason-Suares
- Laboratory for Molecular Medicine; Partners Healthcare Personalized Medicine; Cambridge MA
- Department of Pathology; Brigham and Women's Hospital; Harvard Medical School; Boston MA
| | - Ashley L. Frisella
- Laboratory for Molecular Medicine; Partners Healthcare Personalized Medicine; Cambridge MA
| | - Mark Bowser
- Laboratory for Molecular Medicine; Partners Healthcare Personalized Medicine; Cambridge MA
| | - Elizabeth Duffy
- Laboratory for Molecular Medicine; Partners Healthcare Personalized Medicine; Cambridge MA
| | - Lisa Mahanta
- Laboratory for Molecular Medicine; Partners Healthcare Personalized Medicine; Cambridge MA
| | - Birgit Funke
- Laboratory for Molecular Medicine; Partners Healthcare Personalized Medicine; Cambridge MA
- Department of Pathology; Brigham and Women's Hospital; Harvard Medical School; Boston MA
| | - Heidi L. Rehm
- Laboratory for Molecular Medicine; Partners Healthcare Personalized Medicine; Cambridge MA
- Department of Pathology; Brigham and Women's Hospital; Harvard Medical School; Boston MA
| | - Sami S. Amr
- Laboratory for Molecular Medicine; Partners Healthcare Personalized Medicine; Cambridge MA
- Department of Pathology; Brigham and Women's Hospital; Harvard Medical School; Boston MA
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Svidnicki MCCM, Silva-Costa SM, Ramos PZ, dos Santos NZP, Martins FTA, Castilho AM, Sartorato EL. Screening of genetic alterations related to non-syndromic hearing loss using MassARRAY iPLEX® technology. BMC MEDICAL GENETICS 2015; 16:85. [PMID: 26399936 PMCID: PMC4581412 DOI: 10.1186/s12881-015-0232-8] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/08/2014] [Accepted: 09/15/2015] [Indexed: 12/13/2022]
Abstract
BACKGROUND Recent advances in molecular genetics have enabled to determine the genetic causes of non-syndromic hearing loss, and more than 100 genes have been related to the phenotype. Due to this extraordinary genetic heterogeneity, a large percentage of patients remain without any molecular diagnosis. This condition imply the need for new methodological strategies in order to detect a greater number of mutations in multiple genes. In this work, we optimized and tested a panel of 86 mutations in 17 different genes screened using a high-throughput genotyping technology to determine the molecular etiology of hearing loss. METHODS The technology used in this work was the MassARRAY iPLEX® platform. This technology uses silicon chips and DNA amplification products for accurate genotyping by mass spectrometry of previous reported mutations. The generated results were validated using conventional techniques, as direct sequencing, multiplex PCR and RFLP-PCR. RESULTS An initial genotyping of control subjects, showed failures in 20 % of the selected alterations. To optimize these results, the failed tests were re-designed and new primers were synthesized. Then, the specificity and sensitivity of the panel demonstrated values above 97 %. Additionally, a group of 180 individuals with NSHL without a molecular diagnosis was screened to test the diagnostic value of our panel, and mutations were identified in 30 % of the cases. In 20 % of the individuals, it was possible to explain the etiology of the HL. Mutations in GJB2 gene were the most prevalent, followed by other mutations in in SLC26A4, CDH23, MT-RNR1, MYO15A, and OTOF genes. CONCLUSIONS The MassARRAY technology has the potential for high-throughput identification of genetic variations. However, we demonstrated that optimization is required to increase the genotyping success and accuracy. The developed panel proved to be efficient and cost-effective, being suitable for applications involving the molecular diagnosis of hearing loss.
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Affiliation(s)
- Maria Carolina Costa Melo Svidnicki
- Human Molecular Genetics Laboratory, Molecular Biology and Genetic Engineering Center (CBMEG), University of Campinas (UNICAMP), Campinas, São Paulo, Brazil.
| | - Sueli Matilde Silva-Costa
- Human Molecular Genetics Laboratory, Molecular Biology and Genetic Engineering Center (CBMEG), University of Campinas (UNICAMP), Campinas, São Paulo, Brazil.
| | - Priscila Zonzini Ramos
- Human Molecular Genetics Laboratory, Molecular Biology and Genetic Engineering Center (CBMEG), University of Campinas (UNICAMP), Campinas, São Paulo, Brazil.
| | - Nathalia Zocal Pereira dos Santos
- Human Molecular Genetics Laboratory, Molecular Biology and Genetic Engineering Center (CBMEG), University of Campinas (UNICAMP), Campinas, São Paulo, Brazil.
| | - Fábio Tadeu Arrojo Martins
- Human Molecular Genetics Laboratory, Molecular Biology and Genetic Engineering Center (CBMEG), University of Campinas (UNICAMP), Campinas, São Paulo, Brazil.
| | - Arthur Menino Castilho
- ENT Department, Faculty of Medical Sciences, University of Campinas (UNICAMP), Campinas, São Paulo, Brazil.
| | - Edi Lúcia Sartorato
- Human Molecular Genetics Laboratory, Molecular Biology and Genetic Engineering Center (CBMEG), University of Campinas (UNICAMP), Campinas, São Paulo, Brazil.
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Sarver AE, Sarver AL, Thayanithy V, Subramanian S. Identification, by systematic RNA sequencing, of novel candidate biomarkers and therapeutic targets in human soft tissue tumors. J Transl Med 2015; 95:1077-88. [PMID: 26121316 DOI: 10.1038/labinvest.2015.80] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Revised: 04/17/2015] [Accepted: 05/11/2015] [Indexed: 01/14/2023] Open
Abstract
Human sarcomas comprise a heterogeneous group of more than 50 subtypes broadly classified into two groups: bone and soft tissue sarcomas. Such heterogeneity and their relative rarity have made them challenging targets for classification, biomarker identification, and development of improved treatment strategies. In this study, we used RNA sequencing to analyze 35 primary human tissue samples representing 13 different sarcoma subtypes, along with benign schwannoma, and normal bone and muscle tissues. For each sarcoma subtype, we detected unique messenger RNA (mRNA) expression signatures, which we further subjected to bioinformatic functional analysis, upstream regulatory analysis, and microRNA (miRNA) targeting analysis. We found that, for each sarcoma subtype, significantly upregulated genes and their deduced upstream regulators included not only previously implicated known players but also novel candidates not previously reported to be associated with sarcoma. For example, the schwannoma samples were characterized by high expression of not only the known associated proteins GFAP and GAP43 but also the novel player GJB6. Further, when we integrated our expression profiles with miRNA expression data from each sarcoma subtype, we were able to deduce potential key miRNA-gene regulator relationships for each. In the Ewing's sarcoma and fibromatosis samples, two sarcomas where miR-182-5p is significantly downregulated, multiple predicted targets were significantly upregulated, including HMCN1, NKX2-2, SCNN1G, and SOX2. In conclusion, despite the small number of samples per sarcoma subtype, we were able to identify key known players; concurrently, we discovered novel genes that may prove to be important in the molecular classification of sarcomas and in the development of novel treatments.
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Affiliation(s)
- Anne E Sarver
- Division of Basic and Translational Research, Department of Surgery, University of Minnesota Medical School, University of Minnesota, Minneapolis, MN, USA
| | - Aaron L Sarver
- Masonic Cancer Center, University of Minnesota, Minneapolis, MN, USA
| | - Venugopal Thayanithy
- Division of Basic and Translational Research, Department of Surgery, University of Minnesota Medical School, University of Minnesota, Minneapolis, MN, USA
| | - Subbaya Subramanian
- Division of Basic and Translational Research, Department of Surgery, University of Minnesota Medical School, University of Minnesota, Minneapolis, MN, USA
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Zaidieh T, Habbal W, Monem F. Screening of GJB6 Gene Large Deletions Among Syrians with Congenital Hearing Impairment. Genet Test Mol Biomarkers 2015; 19:405-7. [PMID: 25989237 DOI: 10.1089/gtmb.2015.0019] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Tarek Zaidieh
- Department of Biochemistry and Microbiology, Faculty of Pharmacy, Damascus University, Damascus, Syria
| | - Wafa Habbal
- Clinical Laboratories Department, Al-Assad Hospital, Damascus University, Damascus, Syria
| | - Fawza Monem
- Department of Biochemistry and Microbiology, Faculty of Pharmacy, Damascus University, Damascus, Syria
- Clinical Laboratories Department, Al-Assad Hospital, Damascus University, Damascus, Syria
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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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Lebeko K, Bosch J, Noubiap JJN, Dandara C, Wonkam A. Genetics of hearing loss in Africans: use of next generation sequencing is the best way forward. Pan Afr Med J 2015; 20:383. [PMID: 26185573 PMCID: PMC4499266 DOI: 10.11604/pamj.2015.20.383.5230] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2014] [Accepted: 09/27/2014] [Indexed: 11/11/2022] Open
Abstract
Hearing loss is the most common communication disorder affecting about 1-7/1000 births worldwide. The most affected areas are developing countries due toextensively poor health care systems. Environmental causes contribute to 50-70% of cases, specifically meningitis in sub-Saharan Africa. The other 30-50% is attributed to genetic factors. Nonsyndromic hearing loss is the most common form of hearing loss accounting for up to 70% of cases. The most common mode of inheritance is autosomal recessive. The most prevalent mutations associated with autosomal recessive nonsyndromic hearing loss (ARNSHL) are found within connexin genes such as GJB2, mostly in people of European and Asian origin. For example, the c.35delG mutation ofGJB2 is found in 70% of ARNSHL patients of European descentand is rare in populations of otherethnicities. Other GJB2 mutations have been reported in various populations. The second most common mutations are found in theconnexin gene, GJB6, also with a high prevalencein patients of European descent. To date more than 60 genes have been associated with ARNSHL. We previously showed that mutations in GJB2, GJB6 and GJA1 are not significant causes of ARNSHL inpatients from African descents, i.e. Cameroonians and South AfricansIn order to resolve ARNSHL amongst sub-Saharan African patients, additional genes would need to be explored. Currently at least 60 genes are thought to play a role in ARNSHL thus the current approach using Sanger sequencing would not be appropriate as it would be expensive and time consuming. Next Generation sequencing (NGS) provides the best alternative approach. In this review, we reported on the success of using NGSas observed in various populations and advocate for the use of NGS to resolve cases of ARNSHL in sub-Saharan African populations.
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Affiliation(s)
- Kamogelo Lebeko
- Division of Human Genetics, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Jason Bosch
- Division of Human Genetics, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | | | - Collet Dandara
- Division of Human Genetics, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa ; Institute for Infectious Disease and Molecular Medicine (IDM), Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Ambroise Wonkam
- Division of Human Genetics, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
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Wonkam A. Letter to the editor regarding "GJB2, GJB6 or GJA1 genes should not be investigated in routine in non syndromic deafness in people of sub-Saharan African descent". Int J Pediatr Otorhinolaryngol 2015; 79:632-3. [PMID: 25639550 DOI: 10.1016/j.ijporl.2015.01.012] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/17/2014] [Accepted: 01/13/2015] [Indexed: 10/24/2022]
Affiliation(s)
- Ambroise Wonkam
- Division of Human Genetics, Faculty of Health Sciences, University of Cape Town (UCT), South Africa.
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73
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Potential treatments for genetic hearing loss in humans: current conundrums. Gene Ther 2015; 22:603-9. [PMID: 25781649 DOI: 10.1038/gt.2015.27] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Revised: 01/24/2015] [Accepted: 02/12/2015] [Indexed: 12/18/2022]
Abstract
Genetic defects are a major cause of hearing loss in newborns. Consequently, hearing loss has a profound negative impact on human daily living. Numerous causative genes for genetic hearing loss have been identified. However, presently, there are no truly curative treatments for this condition. There have been several recent reports on successful treatments in mice using embryonic gene therapy, neonatal gene therapy and neonatal antisense oligonucleotide therapy. Herein, we describe state-of-the-art research on genetic hearing loss treatment through gene therapy and discuss the obstacles to overcome in curative treatments of genetic hearing loss in humans.
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Ordóñez J, Diaz-Horta O, Tekin M. Personalized Medicine for Hereditary Deafness. Rare Dis 2015. [DOI: 10.1007/978-94-017-9214-1_4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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Haraksingh RR, Jahanbani F, Rodriguez-Paris J, Gelernter J, Nadeau KC, Oghalai JS, Schrijver I, Snyder MP. Exome sequencing and genome-wide copy number variant mapping reveal novel associations with sensorineural hereditary hearing loss. BMC Genomics 2014; 15:1155. [PMID: 25528277 PMCID: PMC4367882 DOI: 10.1186/1471-2164-15-1155] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2014] [Accepted: 12/12/2014] [Indexed: 11/17/2022] Open
Abstract
Background The genetic diversity of loci and mutations underlying hereditary hearing loss is an active area of investigation. To identify loci associated with predominantly non-syndromic sensorineural hearing loss, we performed exome sequencing of families and of single probands, as well as copy number variation (CNV) mapping in a case–control cohort. Results Analysis of three distinct families revealed several candidate loci in two families and a single strong candidate gene, MYH7B, for hearing loss in one family. MYH7B encodes a Type II myosin, consistent with a role for cytoskeletal proteins in hearing. High-resolution genome-wide CNV analysis of 150 cases and 157 controls revealed deletions in genes known to be involved in hearing (e.g. GJB6, OTOA, and STRC, encoding connexin 30, otoancorin, and stereocilin, respectively), supporting CNV contributions to hearing loss phenotypes. Additionally, a novel region on chromosome 16 containing part of the PDXDC1 gene was found to be frequently deleted in hearing loss patients (OR = 3.91, 95% CI: 1.62-9.40, p = 1.45 × 10-7). Conclusions We conclude that many known as well as novel loci and distinct types of mutations not typically tested in clinical settings can contribute to the etiology of hearing loss. Our study also demonstrates the challenges of exome sequencing and genome-wide CNV mapping for direct clinical application, and illustrates the need for functional and clinical follow-up as well as curated open-access databases. Electronic supplementary material The online version of this article (doi:10.1186/1471-2164-15-1155) contains supplementary material, which is available to authorized users.
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Affiliation(s)
| | | | | | | | | | | | | | - Michael P Snyder
- Department of Genetics, Stanford University School of Medicine, 300 Pasteur Dr,, M-344A, Stanford, CA 94305, USA.
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Najmabadi H, Kahrizi K. Genetics of non-syndromic hearing loss in the Middle East. Int J Pediatr Otorhinolaryngol 2014; 78:2026-36. [PMID: 25281338 DOI: 10.1016/j.ijporl.2014.08.036] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/18/2014] [Revised: 08/24/2014] [Accepted: 08/25/2014] [Indexed: 12/23/2022]
Abstract
Hearing impairment is the most common sensory disorder, present 1 in every 500 newborns. About 80% of genetic HL is classified as non-syndromic deafness. To date, over 115 non-syndromic loci have been identified of which fifty associated with autosomal recessive non-syndromic hearing loss (ARNSHL). In this review article, we represent the 40 genes function and contribution to genetic deafness in different Middle Eastern populations as well as gene frequencies and mutation spectrum. The wide variety of mutations have so far detected in 19 countries reflects the heterogeneity of the genes involved in HL in this region. The deafness genes can cause dysfunction of cochlear homeostasis, cellular organization, neuronal transmission, cell growth, differentiation, and survival, some coding for tectorial membrane-associated proteins, and the remaining with unknown functions. Non-syndromic deafness is highly heterogeneous and mutations in the GJB2 are responsible for almost 30-50% in northwest to as low as 0-5% in south and southeast of the Middle East, it remain as major gene in ARNSHL in Middle East. The other genes contributing to AR/ADNSHL in some countries have been determined while for many other countries in the Middle East have not been studied or little study has been done. With the advancement of next generation sequencing one could expect in next coming year many of the remaining genes to be determine and to understand their function in the inner ear.
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Affiliation(s)
- Hossein Najmabadi
- Genetics Research Centre (GRC), University of Social Welfare and Rehabilitation Sciences, Tehran, Iran.
| | - Kimia Kahrizi
- Genetics Research Centre (GRC), University of Social Welfare and Rehabilitation Sciences, Tehran, Iran
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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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Ridal M, Outtasi N, Taybi Z, Boulouiz R, Chaouki S, Boubou M, Maaroufi M, Benmansour N, Zaki Z, Ouldim K, Barakat H, Hida M, Tizniti S, El Alami MN. [Etiologic profile of severe and profound sensorineural hearing loss in children in the region of north-central Morocco]. Pan Afr Med J 2014; 17:100. [PMID: 25018837 PMCID: PMC4081148 DOI: 10.11604/pamj.2014.17.100.2331] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2012] [Accepted: 11/28/2013] [Indexed: 11/24/2022] Open
Abstract
Introduction Le diagnostic d'une surdité profonde est possible dès les premiers jours de vie. Or, le développement du langage et l'intégration scolaire et professionnelle ne sont pas possible que si la surdité est prise en charge précocement. L’établissement d'un diagnostc étiologique a des implications pronostiques et thérapeutiques. Méthodes C'est une étude rétrospective allant de Juin 2009 au mois de Janvier 2012 ayant recensé 250 cas d'enfants porteurs d'une surdité sévère et profonde. Résultats La moyenne d’âge au moment de l'annonce du diagnostic est de 3.7 ans. Les étiologies prédominantes sont les surdités génétiques dans 35.6% suivies des surdités acquises dans 30.8% des cas. Dans 34.4% des cas aucune étiologie n'a pu être retrouvée. Conclusion Cette étude met en évidence la prédominance éventuelle de causes génétiques de la surdité neurosensorielle de l'enfant au Maroc, et souligne la nécessité d'améliorer les politiques de prévention des maladies infectieuses et de dépistage de la surdité néonatale. Cependant, des analyses moléculaires plus ciblées et la réalisation d'un scanner des rochers systématiques sont nécessaires pour évaluer plus précisément la contribution des étiologies génétiques.
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Affiliation(s)
- Mohammed Ridal
- Service d'Oto-Rhino-Laryngologie, CHU Hassan II Fés et faculté de médecine de Fès, Maroc
| | - Naouar Outtasi
- Service d'Oto-Rhino-Laryngologie, CHU Hassan II Fés et faculté de médecine de Fès, Maroc
| | - Zainab Taybi
- Service d'Oto-Rhino-Laryngologie, CHU Hassan II Fés et faculté de médecine de Fès, Maroc
| | - Redouan Boulouiz
- Laboratoire de biologie moléculaire, Institut Pasteur Casablanca, Maroc
| | | | | | | | - Najib Benmansour
- Service d'Oto-Rhino-Laryngologie, CHU Hassan II Fés et faculté de médecine de Fès, Maroc
| | - Zouheir Zaki
- Service d'Oto-Rhino-Laryngologie, CHU Hassan II Fés et faculté de médecine de Fès, Maroc
| | - Karim Ouldim
- Laboraoire de génétique médicale, CHU Hassan II Fès, Maroc
| | - Hamid Barakat
- Laboratoire de biologie moléculaire, Institut Pasteur Casablanca, Maroc
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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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Salvago P, Martines E, La Mattina E, Mucia M, Sammarco P, Sireci F, Martines F. Distribution and phenotype of GJB2 mutations in 102 Sicilian patients with congenital non syndromic sensorineural hearing loss. Int J Audiol 2014; 53:558-63. [PMID: 24793888 DOI: 10.3109/14992027.2014.905717] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
OBJECTIVE To evaluate the frequency of GJB2 mutations and their correlation with phenotype in Sicilian non-syndromic sensorineural hearing loss (NSHL) 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 102 Sicilian NSHL patients. RESULTS Fifteen different mutations in GJB2 and seventeen different genotypes were detected. No GJB6 mutations were found. The hearing impairment was profound in the 64.72% of probands (mean PTA0.25-4 kHz of 88.82 ± 26.52 dB HL). A total of 81.37% of patients harboured at least one c.35delG allele; c.167delT and c.-23 + 1G> A were identified in 10.78% and the 9.8% of patients respectively; c.35delG homozygotes presented more severe hearing impairment (75.59% of profound hearing loss) and a higher mean PTA0.25-4 kHz (96.79 ± 21.11 dB HL) with respect to c.35delG/non-c.35delG and c.35delG/Wt patients (P < 0.05). CONCLUSIONS This work underlines the role of c.35delG, c.167delT and c.-23 + 1G> A as the most frequent causes of NSHL in Sicily. The c.35delG frequency found is similar to those reported in other populations of the Mediterranean area. The analysis of genetic and audiologic data confirmed a variability in the phenotype associated to a single genotype.
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Affiliation(s)
- Pietro Salvago
- * Dipartimento di Biomedicina Sperimentale e Neuroscienze Cliniche, (BioNeC), Sezione di Otorinolaringoiatria, Università degli Studi di Palermo , Palermo , Italy
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Bliznetz EA, Makienko ON, Okuneva EG, Markova TG, Polyakov AV. New recurrent large deletion, encompassing both GJB2 and GB6 genes, results in isolated sensorineural hearing impairment with autosomal recessive mode of inheritance. RUSS J GENET+ 2014. [DOI: 10.1134/s1022795414020045] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Bosch J, Lebeko K, Nziale JJN, Dandara C, Makubalo N, Wonkam A. In search of genetic markers for nonsyndromic deafness in Africa: a study in Cameroonians and Black South Africans with the GJB6 and GJA1 candidate genes. OMICS-A JOURNAL OF INTEGRATIVE BIOLOGY 2014; 18:481-5. [PMID: 24785695 DOI: 10.1089/omi.2013.0166] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Deafness is the most common sensory disability in the world and has a variety of causes. Globally, mutations in GJB2 have been shown to play a major role in nonsyndromic deafness, but this has not been seen in Africans. Two other connexin genes, GJB6 and GJA1, have been implicated in hearing loss but have seldom been investigated in African populations. We set out to investigate the role of genetic variation in GJB6 and GJA1 in a group of Cameroonian and South African Blacks with nonsyndromic recessive hearing loss. A subset of 100 patients, affected with nonsyndromic hearing loss, from a cohort that was previously shown not to have GJB2 mutation, was analyzed by Sanger sequencing of the entire coding regions of GJB6 and GJA1. In addition, the large-scale GJB6-D3S1830 deletion was also investigated. No pathogenic mutation was detected in either GJB6 or GJA1, nor was the GJB6-D3S1830 deletion detected. There were no statistically significant differences in sequence variants between patients and controls. Mutations in GJB6 and GJA1 are not a major cause of nonsyndromic deafness in this group of Africans from Cameroon and South Africa. Currently, there is no sufficient evidence to support their testing in a clinical setting for individuals of African ancestry.
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Affiliation(s)
- Jason Bosch
- 1 Division of Human Genetics, Department of Clinical Laboratory Sciences, Faculty of Health Sciences, University of Cape Town , Cape Town, South Africa
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Huang A, Yuan Y, Duan N, Jiang X, Wang B, Liu Y, Kang D, Zhang X, Zhu Q, Dai P. Hearing loss associated with an unusual mutation combination in the gap junction beta 2 (GJB2) gene in a Chinese family. Int J Pediatr Otorhinolaryngol 2014; 78:599-603. [PMID: 24503448 DOI: 10.1016/j.ijporl.2014.01.008] [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: 10/30/2013] [Revised: 01/08/2014] [Accepted: 01/08/2014] [Indexed: 10/25/2022]
Abstract
OBJECTIVE To assess the molecular etiology of nonsyndromic sensorineural hearing loss (NSHL) in members of an affected Chinese family. METHODS Common hearing-related genes including gap junction beta 2 (GJB2), SLC26A4, mitochondrial DNA 12S rRNA, GJB3 and GJB6 were examined in a family consisting of a normal hearing father, an NSHL-affected mother, one normal-hearing child and three NSHL-affected children. Specific primers were used in polymerase chain reactions to amplify the coding regions of the above genes from the peripheral blood DNA from each family member, and the genes were analyzed by direct sequencing. The subjects were evaluated for phenotypic characterization using audiometric testing and radiological examination of the inner ear. RESULTS Pathogenic mutations in the GJB2 gene were identified. The affected mother showed a heterozygous G→A transition at nucleotide 232, resulting in an alanine to threonine substitution at codon 78 (p.A78T), and the normal hearing father had a c.35insG insertion mutation. The three affected children displayed heterozygosity for the GJB2 mutations, showing a previously unreported combination of c.35insG and c.232G>A. CONCLUSIONS The GJB2 mutations account for a significant proportion of NSHL in affected individuals worldwide. Genetic and audiological data analysis of a Chinese family with NSHL revealed a novel c.35insG/c.232G>A compound heterozygous state. Our results highlight the complexity of the GJB2 genotypes and phenotypes.
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Affiliation(s)
- Aiping Huang
- Department of Otolaryngology, Head & Neck Surgery, The Second Hospital of Hebei Medical University, Shijiazhuang 050018, Hebei, China; Department of Otolaryngology, Head & Neck Surgery, Chinese PLA General Hospital, Beijing 100853, China
| | - Yongyi Yuan
- Department of Otolaryngology, Head & Neck Surgery, Chinese PLA General Hospital, Beijing 100853, China
| | - Naichao Duan
- Department of Otolaryngology, Head & Neck Surgery, The Second Hospital of Hebei Medical University, Shijiazhuang 050018, Hebei, China
| | - Xinxia Jiang
- Department of Otolaryngology, Head & Neck Surgery, The Second Hospital of Hebei Medical University, Shijiazhuang 050018, Hebei, China
| | - Baoshan Wang
- Department of Otolaryngology, Head & Neck Surgery, The Second Hospital of Hebei Medical University, Shijiazhuang 050018, Hebei, China
| | - Yanping Liu
- Department of Otolaryngology, Head & Neck Surgery, The Second Hospital of Hebei Medical University, Shijiazhuang 050018, Hebei, China
| | - Dongyang Kang
- Department of Otolaryngology, Head & Neck Surgery, Chinese PLA General Hospital, Beijing 100853, China
| | - Xin Zhang
- Department of Otolaryngology, Head & Neck Surgery, Chinese PLA General Hospital, Beijing 100853, China
| | - Qingwen Zhu
- Department of Otolaryngology, Head & Neck Surgery, The Second Hospital of Hebei Medical University, Shijiazhuang 050018, Hebei, China.
| | - Pu Dai
- Department of Otolaryngology, Head & Neck Surgery, Chinese PLA General Hospital, Beijing 100853, China.
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American College of Medical Genetics and Genomics guideline for the clinical evaluation and etiologic diagnosis of hearing loss. Genet Med 2014; 16:347-55. [PMID: 24651602 DOI: 10.1038/gim.2014.2] [Citation(s) in RCA: 159] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2014] [Accepted: 01/06/2014] [Indexed: 01/24/2023] Open
Abstract
Hearing loss is a common and complex condition that can occur at any age, can be inherited or acquired, and is associated with a remarkably wide array of etiologies. The diverse causes of hearing loss, combined with the highly variable and often overlapping presentations of different forms of hearing loss, challenge the ability of traditional clinical evaluations to arrive at an etiologic diagnosis for many deaf and hard-of-hearing individuals. However, identifying the etiology of a hearing loss may affect clinical management, improve prognostic accuracy, and refine genetic counseling and assessment of the likelihood of recurrence for relatives of deaf and hard-of-hearing individuals. Linguistic and cultural identities associated with being deaf or hard of hearing can complicate access to and the effectiveness of clinical care. These concerns can be minimized when genetic and other health-care services are provided in a linguistically and culturally sensitive manner. This guideline offers information about the frequency, causes, and presentations of hearing loss and suggests approaches to the clinical evaluation of deaf and hard-of-hearing individuals aimed at identifying an etiologic diagnosis and providing informative and effective patient education and genetic counseling.
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Melo US, Santos S, Cavalcanti HG, Andrade WT, Dantas VG, Rosa MRD, Mingroni-Netto RC. Strategies for genetic study of hearing loss in the Brazilian northeastern region. INTERNATIONAL JOURNAL OF MOLECULAR EPIDEMIOLOGY AND GENETICS 2014; 5:11-21. [PMID: 24596593 PMCID: PMC3939003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 11/14/2013] [Accepted: 01/16/2014] [Indexed: 06/03/2023]
Abstract
The overall aim of this study was to estimate the contribution of genetic factors to the etiology of hearing loss (HL) in two counties in the Brazilian northeastern region. A cross-sectional study, based on the key informant approach (KI) was conducted in Queimadas and Gado Bravo counties (Paraíba, Northeast Brazil). The sample consisted of 182 patients with HL. Genetic screening of the most frequent mutations associated with HL was performed for all samples. DFNB1 mutations were the most frequently found in both counties. The c.35delG mutation was detected in homozygosis in seven non-syndromic probands in Queimadas (7/76, 9.2%) and only a single homozygote with this mutation was found in Gado Bravo (1/44, 2.3%). We also detected the del(GJB6-D13S1854) mutation in non-syndromic probands from Gado Bravo (2/44, 4.5%). The c.189C>A (p.TyrY63*) mutation in the CLRN1 gene was detected in homozygosis in 21/23 Usher syndrome patients from Gado Bravo and it was not found in Queimadas. Cases with probable genetic etiology contributed approximately to half of HL probands in each county (54.6% in Gado Bravo and 45.7% in Queimadas). We confirm the importance of DFNB1 locus to non-syndromic HL but we show that the frequency of mutations in the northeastern region differs somewhat from those reported in southeastern Brazil and other populations. In addition, the extremely high frequency of individuals with Usher syndrome with c.189C>A variation in CLRN1 indicates the need for a specific screening of this mutation.
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Affiliation(s)
- Uirá S Melo
- Departamento de Genética e Biologia Evolutiva da Universidadede São Paulo, São Paulo, Brazil
| | - Silvana Santos
- Núcleo de Estudos em Genética e Educação da UniversidadeEstadual da Paraíba,Paraíba, Brazil
| | | | - Wagner T Andrade
- Departamento de Fonoaudiologia da UniversidadeFederal da Paraíba, Paraíba, Brazil
| | - Vitor G Dantas
- Departamento de Genética e Biologia Evolutiva da Universidadede São Paulo, São Paulo, Brazil
| | - Marine RD Rosa
- Departamento de Fonoaudiologia da UniversidadeFederal da Paraíba, Paraíba, Brazil
| | - Regina C Mingroni-Netto
- Departamento de Genética e Biologia Evolutiva da Universidadede São Paulo, São Paulo, Brazil
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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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88
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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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Identification of a SNP in a regulatory region of GJB2 associated with idiopathic nonsyndromic autosomal recessive hearing loss in a multicenter study. Otol Neurotol 2013; 34:650-6. [PMID: 23640091 DOI: 10.1097/mao.0b013e31828d6501] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
HYPOTHESIS Additional genetic changes in the regulatory region of the human GJB2 gene encoding the gap junction protein (Connexin 26) may contribute to sensorineural hearing loss. BACKGROUND Mutations in GJB2 cause up to 50% of autosomal recessive nonsyndromic hearing impairment (NSHI). METHODS In the present study, we screened the putative 5' GJB2 regulatory region for novel alterations. RESULTS In idiopathic familial cases of NSHI lacking known pathogenic alterations in GJB2, we identified a T→C transition (refSNP: rs117685390) in a putative transcription factor binding sequence 228 bp proximal to the transcriptional start site at a homozygous frequency of 0.125 (n = 40), significantly overrepresented in comparison to the homozygous allele frequencies of 0.043 in the normal-hearing Caucasian population (n = 211; p < 0.001). In a NSHI family, inheritance of the rs117685390 C allele segregated on independent chromosomes with NSHI in conjunction with heterozygous inheritance of c.35delG, the most common Caucasian mutation in the GJB2 coding region. In a patient group (n = 32) bearing heterozygous pathogenic c.35delG mutations, - rs117685390 C allele homozygosity was also highly overrepresented (0.25; p < 0.001) and not exclusively linked to the c.35delG mutation in cis in patients homozygous for c.35delG. However, in the majority of NSHI homozygous c.35delG chromosomes examined (91/94), c.35delG homozygosity was linked to the rs117685390 C allele in cis. CONCLUSION These results suggest that the rs117685390 C allele could represent a biomarker for the development of NSHI in Caucasian populations and may be included in risk assessment for the development of NSHI.
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Dalamón V, Florencia Wernert M, Lotersztein V, Craig PO, Diamante RR, Barteik ME, Curet C, Paoli B, Mansilla E, Elgoyhen AB. Identification of four novel connexin 26 mutations in non-syndromic deaf patients: genotype-phenotype analysis in moderate cases. Mol Biol Rep 2013; 40:6945-55. [PMID: 24158611 DOI: 10.1007/s11033-013-2814-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2012] [Accepted: 10/16/2013] [Indexed: 10/26/2022]
Abstract
This paper presents a mutation as well as a genotype-phenotype analysis of the GJB2 and GJB6 genes in 476 samples from non-syndromic unrelated Argentinean deaf patients (104 familial and 372 sporadic cases). Most of them were of prelingual onset (82 %) and 27 % were cochlear implanted. Variation of sequences was detected in 171 of the 474 patients (36 %). Overall, 43 different sequence variations were identified in GJB2 and GJB6. Four of them are reported for the first time in GJB2: c.233dupG, p.Ala78Ser, p.Val190Asp and p.Cys211Tyr. Mutations in GJB6 were detected in 3 % of patients [nine del(GJB6-D13S1830) and three del(GJB6-D13S1854)]. Of the 43 different variations identified in GJB2, 6 were polymorphisms and of the others, 10 (27 %) were truncating and 27 (73 %) were nontruncating. Patients with two truncating mutations had significantly worse hearing impairment than all other groups. Moderate phenotypes were observed in a group of patients carrying biallelic mutations (23 %). This work shows the high prevalence of GJB2 mutations in the Argentinean population and presents an analysis of moderate phenotypes in our cohort.
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Affiliation(s)
- Viviana Dalamón
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular, Dr. Héctor N. Torres (INGEBI) Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Ciudad Autónoma de Buenos Aires, Argentina,
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Abstract
Hearing impairment is the most common sensory deficit in humans affecting 1 in 1000 newborns. When present in an infant, deafness may have dramatic effects on language acquisition, seriously compromising the quality of their life. Deafness is influenced by both genetic and environmental factors, with inherited causes as the most prominent etiological factor in deafness in developed countries. The genetic basis of hearing loss is complex with numerous loci and genes underlying hereditary sensoryneural non syndromic hearing loss (NSHL) in humans. Despite the wide functional heterogeneity of the genes, mutations in the GJB2 gene are found to be the most common cause of sporadic and recessive NSHL in many populations worldwide. Molecular characterization of deafness in the Republic of Macedonia was performed in 130 NSHL profoundly deaf children from different ethnic origins. Molecular studies included direct sequencing of the GJB2 gene and specific polymerase chain reaction (PCR) analyses for the del(GJB6-D13S1830) mutation. Five common mitochondrial DNA (mtDNA) mutations [A1555G, 961delT+ C(n), T1095C, C1494T and A827G] were also analyzed using the SNaPShot method. In preliminary studies, GJB2 gene mutations were found in 36.4% of analyzed patients, with predominance of 35delG in Macedonian and Albanian patients and W24X in Gypsy patients, respectively. No del(GJB6-D13S1830) mutation was found. None of the analyzed deafness-associated mutations in mtDNA were identified in the studied patients.
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92
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A novel splice-site mutation in the GJB2 gene causing mild postlingual hearing impairment. PLoS One 2013; 8:e73566. [PMID: 24039984 PMCID: PMC3765306 DOI: 10.1371/journal.pone.0073566] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2013] [Accepted: 07/19/2013] [Indexed: 11/26/2022] Open
Abstract
The DFNB1 subtype of autosomal recessive, nonsyndromic hearing impairment, caused by mutations affecting the GJB2 (connection-26) gene, is highly prevalent in most populations worldwide. DFNB1 hearing impairment is mostly severe or profound and usually appears before the acquisition of speech (prelingual onset), though a small number of hypomorphic missense mutations result in mild or moderate deafness of postlingual onset. We identified a novel GJB2 splice-site mutation, c. -22-2A>C, in three siblings with mild postlingual hearing impairment that were compound heterozygous for c. -22-2A>C and c.35delG. Reverse transcriptase-PCR experiments performed on total RNA extracted from saliva samples from one of these siblings confirmed that c. -22-2A>C abolished the acceptor splice site of the single GJB2 intron, resulting in the absence of normally processed transcripts from this allele. However, we did isolate transcripts from the c. -22-2A>C allele that keep an intact GJB2 coding region and that were generated by use of an alternative acceptor splice site previously unknown. The residual expression of wild-type connection-26 encoded by these transcripts probably underlies the mild severity and late onset of the hearing impairment of these subjects.
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93
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Ramos PZ, de Moraes VCS, Svidnicki MCCM, Soki MN, Castilho AM, Sartorato EL. Etiologic and diagnostic evaluation: Algorithm for severe to profound sensorineural hearing loss in Brazil. Int J Audiol 2013; 52:746-52. [DOI: 10.3109/14992027.2013.817689] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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94
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Zhang Y, Hao H. Conserved glycine at position 45 of major cochlear connexins constitutes a vital component of the Ca²⁺ sensor for gating of gap junction hemichannels. Biochem Biophys Res Commun 2013; 436:424-9. [PMID: 23756814 DOI: 10.1016/j.bbrc.2013.05.118] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2013] [Accepted: 05/29/2013] [Indexed: 11/28/2022]
Abstract
Mutations in gap junction (GJ) family of proteins, especially in the connexin (Cx) 26, are responsible for causing severe congenital hearing loss in a significant portion of patients (30-50% in various ethnic groups). Substitution of glycine at the position 45 of Cx26 to glutamic acid (p.G45E mutation) causes the Keratitis-ichthyosis-deafness (KID) syndrome. Previous studies have suggested that this point mutation caused a gain-of-function defect. However, the molecular mechanism of KID syndrome remains unclear. Since glycine at this position is conserved in many Cxs expressed in the cochlea, we tested the hypothesis that glycine at position 45 is an important component of the sensor regulating the Ca(2+) gating of GJ hemichannels. Using reconstituted Cx30, 32 and 43 expressed in the HEK 293 cells, we compared the functions of wild type and p.G45E mutant Cxs. We found that G45E in Cx30 resulted in similar deleterious cellular effects as Cx26 did. Cell death occurred within 24h of transfection, which was rescued by increasing extracellular Ca(2+) concentration ([Ca(2+)]o). Dye loading assay showed that Cx30 G45E, similar to Cx26 G45E, had leaky hemichannels at physiological [Ca(2+)]o (1.2 mM). Higher [Ca(2+)]o reduced the dye loading in a dose-dependent manner. Whole cell membrane current recordings also indicated that G45E caused increased hemichannel activities. p.G45E mutations of Cx32 and 43 also resulted in leaky hemichannels compared to their respective wild types in lower [Ca(2+)]o. Our data in this study provided further support for the hypothesis that glycine at position 45 is a conserved Ca(2+) sensor for the gating of GJ hemichannels among multiple Cx subtypes expressed in the cochlea.
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Affiliation(s)
- Yanping Zhang
- Department of Otolaryngology, 309th Hospital of Chinese PLA, Road Heishanhu, Haidian District, Beijing 100091, China.
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95
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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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Prevalence of DFNB1 mutations among cochlear implant users in Slovakia and its clinical implications. Eur Arch Otorhinolaryngol 2013; 271:1401-7. [PMID: 23700267 DOI: 10.1007/s00405-013-2559-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2013] [Accepted: 05/04/2013] [Indexed: 10/26/2022]
Abstract
Hereditary etiology plays an important role in bilateral profound deafness as a main indication for cochlear implantation. Mutations in DFNB1 locus account for most of the inherited deafness cases in Caucasians. To provide actual data on mutation prevalence among implanted deaf subpopulation, we performed DNA analysis of GJB2 and GJB6 genes in 131 unrelated Slovak cochlear implant users. Eight previously described causal mutations and one probably pathogenic missense variant (c.127G>A) were detected in the GJB2 gene in 58 (44.28%) subjects. The most common mutation found was c.35delG with frequency 83.02% of all disease alleles, followed by c.71G>A, c.1-3201G>A, c.313_326del14, c.109G>A, 167delT, c.269T>C, and c.333_334delAA. GJB6 deletion delD13S1830 was identified in only one subject, in double heterozygosity with a GJB6 mutation. Thus, the deafness cause could be clearly attributable to DFNB1 mutations in 36.64% of the patients examined. In summary, the mutation profile found in our cohort was similar to the mutation spectrum reported for Central European deaf populations. The mutation prevalence in cochlear implant users was, however, almost by 25% higher than previously established for non-implanted hearing-impaired population in Slovakia. Finally, we also demonstrate a certain variability in deafness onset in patients with causal genotype and coincidence with other risk factors for deafness. Our results underline the importance of genetic tests in all cochlear implant candidates.
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98
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EMQN Best Practice guidelines for diagnostic testing of mutations causing non-syndromic hearing impairment at the DFNB1 locus. Eur J Hum Genet 2013; 21:1325-9. [PMID: 23695287 PMCID: PMC3798855 DOI: 10.1038/ejhg.2013.83] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
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Trabelsi M, Bahri W, Habibi M, Zainine R, Maazoul F, Ghazi B, Chaabouni H, Mrad R. GJB2 and GJB6 screening in Tunisian patients with autosomal recessive deafness. Int J Pediatr Otorhinolaryngol 2013; 77:714-6. [PMID: 23434199 DOI: 10.1016/j.ijporl.2013.01.024] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/23/2012] [Revised: 01/18/2013] [Accepted: 01/26/2013] [Indexed: 10/27/2022]
Abstract
UNLABELLED Autosomal recessive nonsyndromic deafness (ARNSD or DFNB) is a very common genetically heterogenous disorder. Although DFNB1 mutations are known to be the most frequent cause of this disorder, they are largely dependent on ethnic groups. The aims of our study are to specify the prevalence and the spectrum of GJB2 mutations as well as the prevalence of GJB6 large deletion in Tunisian population. PATIENTS AND METHODS 95 unrelated patients with moderate to severe sensorineural hearing loss have been tested. The GJB2 coding region has been studied by PCR/Sequencing and the del(GJB6-D13S1830) mutation has been screened by fluorescent PCR multiplex. RESULTS 27.36% of patients present mutations on both alleles of GJB2 gene and no one has the del(GJB6-D13S1830) mutation. The c.35delG mutation represents 86.5% of GJB2 deafness alleles and is found in homozygous state in 22 patients and in heterozygous state in one patient. Four other mutations are detected in four probands: two are compound heterozygous for the p.V37I/p.E47X and the c.35delG/p.R184P mutations, and two are homozygous for the p.E47X and the c.333-334delAA mutations. CONCLUSION Our results showed that c.35delG is the most common but not the only GJB2 mutation and that the del(GJB6-del D13S1830) is absent in our cohort. Consequently, we propose a systematic sequencing of GJB2 coding region for ARNSD Tunisian patients and we suggest additional studies to specify the real prevalence of del(GJB6-D13S1830) in our population.
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Affiliation(s)
- Mediha Trabelsi
- Charles Nicolle Hospital, Congenital and Hereditary Diseases, Tunis, Tunisia.
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Vele O, Schrijver I. Inherited hearing loss: molecular genetics and diagnostic testing. ACTA ACUST UNITED AC 2013; 2:231-48. [PMID: 23495655 DOI: 10.1517/17530059.2.3.231] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
BACKGROUND Hearing loss is a clinically and genetically heterogeneous condition with major medical and social consequences. It affects up to 8% of the general population. OBJECTIVE This review recapitulates the principles of auditory physiology and the molecular basis of hearing loss, outlines the main types of non-syndromic and syndromic deafness by mode of inheritance, and provides an overview of current clinically available genetic testing. METHODS This paper reviews the literature on auditory physiology and on genes, associated with hearing loss, for which genetic testing is presently offered. RESULTS/CONCLUSION The advent of molecular diagnostic assays for hereditary hearing loss permits earlier detection of the underlying causes, facilitates appropriate interventions, and is expected to generate the data necessary for more specific genotype-phenotype correlations.
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Affiliation(s)
- Oana Vele
- Stanford University School of Medicine, Department of Pathology and Pediatrics, L235, 300 Pasteur Drive, Stanford, CA 94305, USA +1 650 724 2403 ; +1 650 724 1567 ;
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