51
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Brotto D, Caserta E, Sorrentino F, Favaretto N, Marioni G, Martini A, Bovo R, Gheller F, Trevisi P. Long-Term Impedance Trend in Cochlear Implant Users with Genetically Determined Congenital Profound Hearing Loss. J Am Acad Audiol 2022; 33:105-114. [PMID: 35577055 DOI: 10.1055/s-0041-1739290] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
BACKGROUND Impedance is a basic parameter registered at any cochlear implant (CI) fitting section. It is useful in monitoring electrode functioning and the status of the surrounding anatomical structures. PURPOSE The main aim of this study is to evaluate the 5-year impedance-value trend in patients affected by congenital genetically determined profound hearing loss implanted with Cochlear Nucleus devices. RESEARCH DESIGN Observational, retrospective, monocentric study. STUDY SAMPLE Twenty-seven consecutive patients (9 females: 12.0 ± 7.6 years old; range: 4.2-40.4) with genetic diagnosis of GJB2 mutation causing congenital profound hearing loss who underwent cochlear implantation from 2010 to 2020 with good auditory benefit. INTERVENTION Impedance values of the CIs were obtained from the CIs' programming software that registers those parameters for each follow-up section of each patient. DATA COLLECTION AND ANALYSIS Impedance values were measured over time (activation, 6, 12, 24, and 60 months after cochlear implantation), for each of the 22 electrodes, in common ground, monopolar 1, monopolar 2, and monopolar 1 + 2 stimulation modes. RESULTS A significant variation was found between CI activation and 6-month follow-up. This difference was found for each of the 22 electrodes. Electrodes 1 to 4 showed higher impedance values compared with all other electrodes in each time interval. Repeated-measures analysis of variance ruled out significant variations in impedance values from 6-month to 5-year follow-up. CONCLUSIONS Impedance values were extremely stable after activation, at least for the first 5 years. In these cases, even minimal impedance variations should be carefully evaluated for their possible implications on hearing performance.
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Affiliation(s)
- Davide Brotto
- Section of Otorhinolaryngology - Head and Neck Surgery, Department of Neurosciences, University of Padova, Padova, Italy
| | - Ezio Caserta
- Section of Otorhinolaryngology - Head and Neck Surgery, Department of Neurosciences, University of Padova, Padova, Italy
| | - Flavia Sorrentino
- Section of Otorhinolaryngology - Head and Neck Surgery, Department of Neurosciences, University of Padova, Padova, Italy
| | - Niccolò Favaretto
- Section of Otorhinolaryngology - Head and Neck Surgery, Department of Neurosciences, University of Padova, Padova, Italy
| | - Gino Marioni
- Section of Otorhinolaryngology - Head and Neck Surgery, Department of Neurosciences, University of Padova, Padova, Italy
| | - Alessandro Martini
- Section of Otorhinolaryngology - Head and Neck Surgery, Department of Neurosciences, University of Padova, Padova, Italy
| | - Roberto Bovo
- Section of Otorhinolaryngology - Head and Neck Surgery, Department of Neurosciences, University of Padova, Padova, Italy
| | - Flavia Gheller
- Section of Otorhinolaryngology - Head and Neck Surgery, Department of Neurosciences, University of Padova, Padova, Italy
| | - Patrizia Trevisi
- Section of Otorhinolaryngology - Head and Neck Surgery, Department of Neurosciences, University of Padova, Padova, Italy
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52
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Stepanova AA, Ismagilova OR, Galeeva NM, Markova TG, Tavartkiladze GA, Kvlividze O, Polyakov AV. Molecular Genetic Study of the Causes of Nonsyndromic Sensorineural Hearing Loss in Patients from Georgia. RUSS J GENET+ 2022. [DOI: 10.1134/s1022795422050106] [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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53
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Connexin Mutations and Hereditary Diseases. Int J Mol Sci 2022; 23:ijms23084255. [PMID: 35457072 PMCID: PMC9027513 DOI: 10.3390/ijms23084255] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2022] [Revised: 04/04/2022] [Accepted: 04/09/2022] [Indexed: 02/01/2023] Open
Abstract
Inherited diseases caused by connexin mutations are found in multiple organs and include hereditary deafness, congenital cataract, congenital heart diseases, hereditary skin diseases, and X-linked Charcot–Marie–Tooth disease (CMT1X). A large number of knockout and knock-in animal models have been used to study the pathology and pathogenesis of diseases of different organs. Because the structures of different connexins are highly homologous and the functions of gap junctions formed by these connexins are similar, connexin-related hereditary diseases may share the same pathogenic mechanism. Here, we analyze the similarities and differences of the pathology and pathogenesis in animal models and find that connexin mutations in gap junction genes expressed in the ear, eye, heart, skin, and peripheral nerves can affect cellular proliferation and differentiation of corresponding organs. Additionally, some dominant mutations (e.g., Cx43 p.Gly60Ser, Cx32 p.Arg75Trp, Cx32 p.Asn175Asp, and Cx32 p.Arg142Trp) are identified as gain-of-function variants in vivo, which may play a vital role in the onset of dominant inherited diseases. Specifically, patients with these dominant mutations receive no benefits from gene therapy. Finally, the complete loss of gap junctional function or altered channel function including permeability (ions, adenosine triphosphate (ATP), Inositol 1,4,5-trisphosphate (IP3), Ca2+, glucose, miRNA) and electric activity are also identified in vivo or in vitro.
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54
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Rouse SL, Florentine MM, Taketa E, Chan DK. Racial and ethnic disparities in genetic testing for hearing loss: a systematic review and synthesis. Hum Genet 2022; 141:485-494. [PMID: 34494120 PMCID: PMC9035011 DOI: 10.1007/s00439-021-02335-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Accepted: 08/09/2021] [Indexed: 11/26/2022]
Abstract
Racial/ethnic disparities in the diagnostic efficacy of genetic testing for hearing loss have been described. These disparities may relate to differences in variant classification between different racial/ethnic groups, which may, in turn, derive from disparate representation of these groups in the published literature. We sought to quantify racial/ethnic disparities in the published literature on the human genetics of hearing loss. We conducted a search of PubMed for articles describing single-gene, multiple-gene, or whole-exome sequencing for individuals with sensorineural hearing loss. Data on the included subjects, including race/ethnicity and/or region of origin, a number of subjects tested, and method of testing, were extracted. 1355 populations representing 311,092 subjects from 1165 studies were included. Overall, subjects of European and Asian ancestry were equivalently represented, but those of Latino American, African, and indigenous North American ancestry were significantly underrepresented; over 96% of all subjects in the published literature were European or Asian. Within populations, the majority of subjects derived from a small subset of countries. The observed disparity was greater for multiple-gene and whole-exome sequencing than for single-gene sequencing. These findings illustrate the large disparity in the published literature on the genetics of hearing loss, and demonstrate the need for increased representation of Latino American, African, and indigenous North American populations.
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Affiliation(s)
| | - Michelle M Florentine
- Department of Otolaryngology-Head and Neck Surgery, University of California-San Francisco, 2233 Post Street, Third Floor, San Francisco, CA, 94115, USA
- Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Emily Taketa
- Department of Otolaryngology-Head and Neck Surgery, University of California-San Francisco, 2233 Post Street, Third Floor, San Francisco, CA, 94115, USA
| | - Dylan K Chan
- Department of Otolaryngology-Head and Neck Surgery, University of California-San Francisco, 2233 Post Street, Third Floor, San Francisco, CA, 94115, USA.
- Division of Pediatric Otolaryngology-Head and Neck Surgery, University of California-San Francisco, 2233 Post Street, Third Floor, San Francisco, CA, 94115, USA.
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55
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Acharya A, Schrauwen I, Leal SM. Identification of autosomal recessive nonsyndromic hearing impairment genes through the study of consanguineous and non-consanguineous families: past, present, and future. Hum Genet 2022; 141:413-430. [PMID: 34291353 PMCID: PMC10416318 DOI: 10.1007/s00439-021-02309-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Accepted: 06/24/2021] [Indexed: 10/20/2022]
Abstract
Hearing impairment (HI) is one of the most common sensory disabilities with exceptionally high genetic heterogeneity. Of genetic HI cases, 30% are syndromic and 70% are nonsyndromic. For nonsyndromic (NS) HI, 77% of the cases are due to autosomal recessive (AR) inheritance. ARNSHI is usually congenital/prelingual, severe-to-profound, affects all frequencies and is not progressive. Thus far, 73 ARNSHI genes have been identified. Populations with high rates of consanguinity have been crucial in the identification of ARNSHI genes, and 92% (67/73) of these genes were identified in consanguineous families. Recent changes in genomic technologies and analyses have allowed a shift towards ARNSHI gene discovery in outbred populations. The latter is crucial towards understanding the genetic architecture of ARNSHI in diverse and understudied populations. We present an overview of the 73 ARNSHI genes, the methods used to identify them, including next-generation sequencing which revolutionized the field, and new technologies that show great promise in advancing ARNSHI discoveries.
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Affiliation(s)
- Anushree Acharya
- Center for Statistical Genetics, Gertrude H. Sergievsky Center, Columbia University Medical Center, New York, NY, USA
- Department of Neurology, Columbia University Medical Center, New York, NY, USA
| | - Isabelle Schrauwen
- Center for Statistical Genetics, Gertrude H. Sergievsky Center, Columbia University Medical Center, New York, NY, USA
- Department of Neurology, Columbia University Medical Center, New York, NY, USA
| | - Suzanne M Leal
- Center for Statistical Genetics, Gertrude H. Sergievsky Center, Columbia University Medical Center, New York, NY, USA.
- Department of Neurology, Columbia University Medical Center, New York, NY, USA.
- Taub Institute for Alzheimer's Disease and the Aging Brain, Columbia University Medical Center, New York, NY, USA.
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56
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Liu W, Rask-Andersen H. Na/K-ATPase Gene Expression in the Human Cochlea: A Study Using mRNA in situ Hybridization and Super-Resolution Structured Illumination Microscopy. Front Mol Neurosci 2022; 15:857216. [PMID: 35431803 PMCID: PMC9009265 DOI: 10.3389/fnmol.2022.857216] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Accepted: 02/23/2022] [Indexed: 12/03/2022] Open
Abstract
Background The pervasive Na/K-ATPase pump is highly expressed in the human cochlea and is involved in the generation of the endocochlear potential as well as auditory nerve signaling and relay. Its distribution, molecular organization and gene regulation are essential to establish to better understand inner ear function and disease. Here, we analyzed the expression and distribution of the ATP1A1, ATP1B1, and ATP1A3 gene transcripts encoding the Na/K-ATPase α1, α3, and β1 isoforms in different domains of the human cochlea using RNA in situ hybridization. Materials and Methods Archival paraformaldehyde-fixed sections derived from surgically obtained human cochleae were used to label single mRNA gene transcripts using the highly sensitive multiplex RNAscope® technique. Localization of gene transcripts was performed by super-resolution structured illumination microscopy (SR-SIM) using fluorescent-tagged probes. GJB6 encoding of the protein connexin30 served as an additional control. Results Single mRNA gene transcripts were seen as brightly stained puncta. Positive and negative controls verified the specificity of the labeling. ATP1A1 and ATP1B1 gene transcripts were demonstrated in the organ of Corti, including the hair and supporting cells. In the stria vascularis, these transcripts were solely expressed in the marginal cells. A large number of ATP1B1 gene transcripts were found in the spiral ganglion cell soma, outer sulcus, root cells, and type II fibrocytes. The ATP1B1 and ATP1A3 gene transcripts were rarely detected in axons. Discussion Surgically obtained inner ear tissue can be used to identify single mRNA gene transcripts using high-resolution fluorescence microscopy after prompt formaldehyde fixation and chelate decalcification. A large number of Na/K-ATPase gene transcripts were localized in selected areas of the cochlear wall epithelium, fibrocyte networks, and spiral ganglion, confirming the enzyme’s essential role for human cochlear function.
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57
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Kenna MA. Genetic testing for pediatric hearing loss: no time to waste. Hum Genet 2022; 141:315-317. [PMID: 35353226 DOI: 10.1007/s00439-021-02333-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2021] [Accepted: 08/04/2021] [Indexed: 11/24/2022]
Abstract
Since the discovery of the first human deafness gene a quarter of a century ago, our approach to clinical evaluation of children with hearing loss has changed dramatically. What was once a low-yield scattershot approach has changed to a clearly definable pathway involving genetic testing, imaging, and congenital cytomegalovirus testing. There still however is a great deal of work to be done to expand the correct use of this testing, particularly genetic testing.
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Affiliation(s)
- Margaret A Kenna
- Sarah Fuller Chair for Hearing Loss and Hearing Restoration, Department of Otolaryngology and Communication Enhancement, Boston Children's Hospital, Harvard Medical School, 300 Longwood Ave. BCH 3129, Boston, MA, 02115, USA.
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58
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Lo TH, Lin PH, Hsu WC, Tsao PN, Liu TC, Yang TH, Hsu CJ, Huang LM, Lu CY, Wu CC. Prognostic determinants of hearing outcomes in children with congenital cytomegalovirus infection. Sci Rep 2022; 12:5219. [PMID: 35338167 PMCID: PMC8956567 DOI: 10.1038/s41598-022-08392-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Accepted: 02/24/2022] [Indexed: 12/20/2022] Open
Abstract
Congenital cytomegalovirus (cCMV) infection is the most prevalent cause of non-genetic sensorineural hearing loss (SNHL) in children. However, the prognostic determinants of SNHL remain unclear. Children with cCMV infection in a tertiary hospital were enrolled. The presence of cCMV-related symptoms at birth, the newborn hearing screening (NHS) results, and the blood viral loads were ascertained. Audiologic outcomes and initial blood viral loads were compared between different groups. Of the 39 children enrolled, 16 developed SNHL. SNHL developed in 60% of children who were initially symptomatic, and in 34.5% of those who were initially asymptomatic with normal hearing or isolated hearing loss, respectively. Failuire in NHS was a reliable tool for early detection of SNHL. The initial viral loads were higher in children who were symptomatic at birth, those who failed NHS, and those who developed SNHL. We observed SNHL deterioration in a patient after CMV DNAemia clearance was achieved, and in another patient with the flare-up of viral load. The presence of cCMV-related symptoms at birth, failure in NHS, and blood viral load might be the prognostic factors for hearing outcomes. Regular audiologic examinations are necessary in all children with cCMV infection even after CMV DNAemia clearance.
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Affiliation(s)
- Ta-Hsuan Lo
- Department of Otolaryngology, National Taiwan University Hospital, Address: 7, Chung-Shan S. Rd., 10002, Taipei, Taiwan, ROC.,Department of Otolaryngology, National Taiwan University Biomedical Park Hospital, Hsinchu, Taiwan
| | - Pei-Hsuan Lin
- Department of Otolaryngology, National Taiwan University Hospital Yunlin Branch, Yunlin, Taiwan
| | - Wei-Chung Hsu
- Department of Otolaryngology, National Taiwan University Hospital, Address: 7, Chung-Shan S. Rd., 10002, Taipei, Taiwan, ROC
| | - Po-Nien Tsao
- Department of Pediatrics, National Taiwan University Hospital, Address: 7, Chung-Shan S. Rd., 10002, Taipei, Taiwan, ROC
| | - Tien-Chen Liu
- Department of Otolaryngology, National Taiwan University Hospital, Address: 7, Chung-Shan S. Rd., 10002, Taipei, Taiwan, ROC
| | - Tzong-Hann Yang
- Department of Otorhinolaryngology, Taipei City Hospital, Taipei, Taiwan
| | - Chuan-Jen Hsu
- Department of Otolaryngology, Taichung Tzu-Chi Hospital, Taichung, Taiwan
| | - Li-Min Huang
- Department of Pediatrics, National Taiwan University Hospital, Address: 7, Chung-Shan S. Rd., 10002, Taipei, Taiwan, ROC
| | - Chun-Yi Lu
- Department of Pediatrics, National Taiwan University Hospital, Address: 7, Chung-Shan S. Rd., 10002, Taipei, Taiwan, ROC.
| | - Chen-Chi Wu
- Department of Otolaryngology, National Taiwan University Hospital, Address: 7, Chung-Shan S. Rd., 10002, Taipei, Taiwan, ROC. .,Department of Medical Genetics, National Taiwan University Hospital, Taipei, Taiwan. .,Graduate Institute of Clinical Medicine, National Taiwan University College of Medicine, Taipei, Taiwan. .,Department of Medical Research, National Taiwan University Biomedical Park Hospital, Hsinchu, Taiwan.
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59
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Liu XZ, Jin Y, Chen S, Xu K, Xie L, Qiu Y, Wang XH, Sun Y, Kong WJ. F-Actin Dysplasia Involved in Organ of Corti Deformity in Gjb2 Knockdown Mouse Model. Front Mol Neurosci 2022; 14:808553. [PMID: 35345836 PMCID: PMC8957075 DOI: 10.3389/fnmol.2021.808553] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Accepted: 12/13/2021] [Indexed: 11/13/2022] Open
Abstract
Mutations in the GJB2 gene encoding connexin26 (Cx26) protein are one of the most common causes of hereditary deafness. Previous studies have found that different Cx26-null mouse models have severe hearing loss and deformity of the organ of Corti (OC) as well as a reduction in microtubules in pillar cells (PCs). To explore the underlying mechanism of OC deformity caused by Cx26 downregulation further, we established Cx26 knockdown (KD) mouse models at postnatal days (P)0 and P8. The actin filaments contained in the pillar cells of mice in the P0 KD group were reduced by 54.85% and vinculin was increased by 22%, while the outer hair cells (OHCs) showed normal F-actin content. In the P8 KD group, PCs and OHCs of mice also showed almost normal F-actin content. The G-actin/F-actin ratio increased by 38% in the P0 KD group. No significant change was found in the mRNA or protein expression level of G-actin or the cadherin–catenin core complex in the P0 KD group at P6. Moreover, immunofluorescence showed that the intensity of LRRK2 was reduced by 97% in the P0 KD group at P6. Our results indicate that Cx26 is involved in the maturation of the cytoskeleton during the development of the OC at the early postnatal stage. The polymerization of G-actin into F-actin is prevented in Cx26 KD mice.
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Affiliation(s)
- Xiao-zhou Liu
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Yuan Jin
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Sen Chen
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Kai Xu
- Department of Otolaryngology, Head and Neck Surgery, The Second Affiliated Hospital of Nanchang University, Nanchang, China
| | - Le Xie
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Yue Qiu
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Xiao-hui Wang
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Yu Sun
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- Institute of Otorhinolaryngology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- *Correspondence: Yu Sun Wei-jia Kong
| | - Wei-jia Kong
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- Institute of Otorhinolaryngology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- *Correspondence: Yu Sun Wei-jia Kong
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60
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Sun L, Gao D, Chen J, Hou S, Li Y, Huang Y, Mammano F, Chen J, Yang J. Failure Of Hearing Acquisition in Mice With Reduced Expression of Connexin 26 Correlates With the Abnormal Phasing of Apoptosis Relative to Autophagy and Defective ATP-Dependent Ca2+ Signaling in Kölliker’s Organ. Front Cell Neurosci 2022; 16:816079. [PMID: 35308122 PMCID: PMC8928193 DOI: 10.3389/fncel.2022.816079] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Accepted: 02/03/2022] [Indexed: 12/11/2022] Open
Abstract
Mutations in the GJB2 gene that encodes connexin 26 (Cx26) are the predominant cause of prelingual hereditary deafness, and the most frequently encountered variants cause complete loss of protein function. To investigate how Cx26 deficiency induces deafness, we examined the levels of apoptosis and autophagy in Gjb2loxP/loxP; ROSA26CreER mice injected with tamoxifen on the day of birth. After weaning, these mice exhibited severe hearing impairment and reduced Cx26 expression in the cochlear duct. Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) positive cells were observed in apical, middle, and basal turns of Kölliker’s organ at postnatal (P) day 1 (P1), associated with increased expression levels of cleaved caspase 3, but decreased levels of autophagy-related proteins LC3-II, P62, and Beclin1. In Kölliker’s organ cells with decreased Cx26 expression, we also found significantly reduced levels of intracellular ATP and hampered Ca2+ responses evoked by extracellular ATP application. These results offer novel insight into the mechanisms that prevent hearing acquisition in mouse models of non-syndromic hearing impairment due to Cx26 loss of function.
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Affiliation(s)
- Lianhua Sun
- Department of Otorhinolaryngology-Head and Neck Surgery, Xinhua Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
- Ear Institute, Shanghai Jiaotong University School of Medicine, Shanghai, China
- Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China
| | - Dekun Gao
- Department of Otorhinolaryngology-Head and Neck Surgery, Xinhua Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
- Ear Institute, Shanghai Jiaotong University School of Medicine, Shanghai, China
- Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China
| | - Junmin Chen
- Department of Otorhinolaryngology-Head and Neck Surgery, Xinhua Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
- Ear Institute, Shanghai Jiaotong University School of Medicine, Shanghai, China
- Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China
| | - Shule Hou
- Department of Otorhinolaryngology-Head and Neck Surgery, Xinhua Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
- Ear Institute, Shanghai Jiaotong University School of Medicine, Shanghai, China
- Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China
| | - Yue Li
- Department of Otorhinolaryngology-Head and Neck Surgery, Xinhua Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
- Ear Institute, Shanghai Jiaotong University School of Medicine, Shanghai, China
- Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China
| | - Yuyu Huang
- Department of Otorhinolaryngology-Head and Neck Surgery, Xinhua Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
- Ear Institute, Shanghai Jiaotong University School of Medicine, Shanghai, China
- Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China
| | - Fabio Mammano
- Department of Physics and Astronomy “G. Galilei”, University of Padua, Padua, Italy
- Department of Biomedical Sciences, Institute of Biochemistry and Cell Biology, Italian National Research Council, Monterotondo, Italy
- *Correspondence: Jun Yang Jianyong Chen Fabio Mammano
| | - Jianyong Chen
- Department of Otorhinolaryngology-Head and Neck Surgery, Xinhua Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
- Ear Institute, Shanghai Jiaotong University School of Medicine, Shanghai, China
- Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China
- *Correspondence: Jun Yang Jianyong Chen Fabio Mammano
| | - Jun Yang
- Department of Otorhinolaryngology-Head and Neck Surgery, Xinhua Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
- Ear Institute, Shanghai Jiaotong University School of Medicine, Shanghai, China
- Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China
- *Correspondence: Jun Yang Jianyong Chen Fabio Mammano
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Rodwin RL, Janardan SK, Hofstatter EW, Kadan-Lottick NS. A Case of Pheochromocytoma as a Subsequent Neoplasm in a Survivor of Childhood Embryonal Rhabdomyosarcoma. J Pediatr Hematol Oncol 2022; 44:e585-e588. [PMID: 35200227 PMCID: PMC8873988 DOI: 10.1097/mph.0000000000002270] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Accepted: 06/02/2021] [Indexed: 11/25/2022]
Abstract
Childhood cancer survivors are at risk for subsequent neoplasms. We describe the clinical presentation and genetic testing of a 29-year-old woman diagnosed with a pheochromocytoma 22 years post-treatment for childhood embryonal rhabdomyosarcoma of the bladder. Genetic testing for cancer predisposition revealed a pathogenic variant in BRCA2 and a variant of uncertain significance in MSH2. Pathogenic variants associated with deafness were also identified in GJB2. This article reports a novel subsequent neoplasm following childhood embryonal rhabdomyosarcoma, and discusses the potential contribution of genetic cancer predisposition to this case as well as the clinical implications of genetic testing.
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Affiliation(s)
- Rozalyn L. Rodwin
- Section of Pediatric Hematology/Oncology, Yale School of Medicine, New Haven, CT
| | - Sanyukta K. Janardan
- Section of Pediatric Hematology/Oncology, Yale School of Medicine, New Haven, CT
- Aflac Cancer and Blood Disorders Center, Emory University School of Medicine/Children’s Healthcare of Atlanta, Atlanta, GA
| | - Erin W. Hofstatter
- Section of Medical Oncology, Yale School of Medicine, New Haven, CT
- Yale Cancer Center, New Haven, CT
| | - Nina S. Kadan-Lottick
- Section of Pediatric Hematology/Oncology, Yale School of Medicine, New Haven, CT
- Yale Cancer Center, New Haven, CT
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Hegde S, Hegde R, Kulkarni SS, Das KK, Gai PB, Bulagouda RS. Analysis of Genetic Variations in Connexin 26 (GJB2) Gene among Nonsyndromic Hearing Impairment: Familial Study. Glob Med Genet 2022; 9:152-158. [PMID: 35707775 PMCID: PMC9192169 DOI: 10.1055/s-0042-1743257] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Accepted: 12/29/2021] [Indexed: 11/24/2022] Open
Abstract
Objective
The goal of this research was to investigate the gap junction beta 2 (
GJB2
) gene mutations associated with nonsyndromic hearing loss individuals in North Karnataka, India.
Materials and Methods
For this study, patients with sensorineural genetic hearing abnormalities and a family history of deafness were included. A total of 35 patients from 20 families have been included in the study. The patient's DNA was isolated from peripheral blood samples. The
GJB2
gene coding region was analyzed through Sanger sequencing.
Results
There is no changes in the first exon of the
GJB2
gene. Nine different variants were recorded in second exon of the targeted gene. W24X and W77X are two nonsense mutations and three polymorphisms viz. R127H, V153I, and I33T were reported along with four 3′-UTR variants. A total (9/20) of 45% of families have been identified with mutations in the targeted gene.
Conclusion
GJB2
mutations were identified in 19 deaf-mute patients (19/35), and 13 patients were homozygous for the mutations identified in our study cohort. In our study, W24X mutation was found to be the pathogenic with a high percentage, prompting further evaluation of the other genes, along with the study of additional genetic or external causes in the families, which is essential.
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Affiliation(s)
- Smita Hegde
- Human Genetics Laboratory, Department of Anatomy, Shri B.M. Patil Medical College, Hospital and Research Centre, BLDE University (Deemed to be University), Vijayapura, Karnataka, India
- Division of Human Genetics, Karnataka Institute for DNA Research, Dharwad, Karnataka, India
| | - Rajat Hegde
- Division of Human Genetics, Karnataka Institute for DNA Research, Dharwad, Karnataka, India
- Laboratory of Vascular Physiology and Medicine, Department of Physiology, Shri B.M. Patil Medical College, Hospital and Research Centre, BLDE University (Deemed to be University), Vijayapura, Karnataka, India
| | - Suyamindra S. Kulkarni
- Division of Human Genetics, Karnataka Institute for DNA Research, Dharwad, Karnataka, India
| | - Kusal K. Das
- Laboratory of Vascular Physiology and Medicine, Department of Physiology, Shri B.M. Patil Medical College, Hospital and Research Centre, BLDE University (Deemed to be University), Vijayapura, Karnataka, India
| | - Pramod B. Gai
- Division of Human Genetics, Karnataka Institute for DNA Research, Dharwad, Karnataka, India
| | - Rudragouda S. Bulagouda
- Human Genetics Laboratory, Department of Anatomy, Shri B.M. Patil Medical College, Hospital and Research Centre, BLDE University (Deemed to be University), Vijayapura, Karnataka, India
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Agent-Based Modeling of Autosomal Recessive Deafness 1A (DFNB1A) Prevalence with Regard to Intensity of Selection Pressure in Isolated Human Population. BIOLOGY 2022; 11:biology11020257. [PMID: 35205123 PMCID: PMC8869167 DOI: 10.3390/biology11020257] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Revised: 01/28/2022] [Accepted: 02/03/2022] [Indexed: 01/09/2023]
Abstract
An increase in the prevalence of autosomal recessive deafness 1A (DFNB1A) in populations of European descent was shown to be promoted by assortative marriages among deaf people. Assortative marriages became possible with the widespread introduction of sign language, resulting in increased genetic fitness of deaf individuals and, thereby, relaxing selection against deafness. However, the effect of this phenomenon was not previously studied in populations with different genetic structures. We developed an agent-based computer model for the analysis of the spread of DFNB1A. Using this model, we tested the impact of different intensities of selection pressure against deafness in an isolated human population over 400 years. Modeling of the "purifying" selection pressure on deafness ("No deaf mating" scenario) resulted in a decrease in the proportion of deaf individuals and the pathogenic allele frequency. Modeling of the "relaxed" selection ("Assortative mating" scenario) resulted in an increase in the proportion of deaf individuals in the first four generations, which then quickly plateaued with a subsequent decline and a decrease in the pathogenic allele frequency. The results of neutral selection pressure modeling ("Random mating" scenario) showed no significant changes in the proportion of deaf individuals or the pathogenic allele frequency after 400 years.
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Genetic etiology of non-syndromic hearing loss in Europe. Hum Genet 2022; 141:683-696. [PMID: 35044523 DOI: 10.1007/s00439-021-02425-6] [Citation(s) in RCA: 27] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2021] [Accepted: 12/20/2021] [Indexed: 12/17/2022]
Abstract
Hearing impairment not etiologically associated with clinical signs in other organs (non-syndromic) is genetically heterogeneous, so that over 120 genes are currently known to be involved. The frequency of mutations in each gene and the most frequent mutations vary throughout populations. Here we review the genetic etiology of non-syndromic hearing impairment (NSHI) in Europe. Over the years, epidemiological data were scarce because of the large number of involved genes, whose screening was not cost-effective until implementation of massively parallel DNA sequencing. In Europe, the most common form of autosomal recessive NSHI is DFNB1, which accounts for 11-57% of the cases. Mutations in STRC account for 16% of the recessive cases, and only a few more (MYO15A, MYO7A, LOXHD1, USH2A, TMPRSS3, CDH23, TMC1, OTOF, OTOA, SLC26A4, ADGRV1 and TECTA) have contributions higher than 2%. As regards autosomal-dominant NSHI, DFNA22 (MYO6) and DFNA8/12 (TECTA) represent the most common forms, accounting for 21% and 18% of elucidated cases, respectively. The contribution of ACTG1 and WFS1 drops to 9% in both cases, followed by POU4F3 (6.5%), MYO7A (5%), MYH14 and COL11A2 (4% each). Four additional genes contribute 2.5% each one (MITF, KCNQ4, EYA4, SOX10) and the remaining are residually represented. X-linked hearing loss and maternally-inherited NSHI have minor contributions in most countries. Further knowledge on the genetic epidemiology of NSHI in Europe needs a standardization of the experimental approaches and a stratification of the results according to clinical features, familial history and patterns of inheritance, to facilitate comparison between studies.
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Zhao LJ, Zhang ZL, Fu Y. Novel m.4268T>C mutation in the mitochondrial tRNA Ile gene is associated with hearing loss in two Chinese families. World J Clin Cases 2022; 10:205-216. [PMID: 35071519 PMCID: PMC8727281 DOI: 10.12998/wjcc.v10.i1.205] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Revised: 07/23/2021] [Accepted: 11/29/2021] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Herein, we report the genetic, clinical, molecular and biochemical features of two Han Chinese pedigrees with suggested maternally transmitted non-syndromic hearing loss.
AIM To investigate the pathophysiology of hearing loss associated with mitochondrial tRNA mutations.
METHODS Sixteen subjects from two Chinese families with hearing loss underwent clinical, genetic, molecular, and biochemical evaluations. Biochemical characterizations included the measurements of tRNA levels using lymphoblastoid cell lines derived from five affected matrilineal relatives of these families and three control subjects.
RESULTS Three of the 16 matrilineal relatives in these families exhibited a variable seriousness and age-at-onset (8 years) of deafness. Analysis of mtDNA mutation identified the novel homoplasmic tRNAIle 4268T>C mutation in two families both belonging to haplogroup D4j. The 4268T>C mutation is located in a highly conserved base pairing (6U–67A) of tRNAIle. The elimination of 6U–67A base-pairing may change the tRNAIle metabolism. Functional mutation was supported by an approximately 64.6% reduction in the level of tRNAIle observed in the lymphoblastoid cell lines with the 4268T>C mutation, in contrast to the wild-type cell lines. The reduced level of tRNA was below the proposed threshold for normal respiration in lymphoblastoid cells. However, genotyping analysis did not detect any mutations in the prominent deafness-causing gene GJB2 in any members of the family.
CONCLUSION These data show that the novel tRNAIle 4268T>C mutation was involved in maternally transmitted deafness. However, epigenetic, other genetic, or environmental factors may be attributed to the phenotypic variability. These findings will be useful for understanding families with maternally inherited deafness.
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Affiliation(s)
- Li-Jing Zhao
- Department of Otorhinolaryngology Head and Neck Surgery, The Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou 310009, Zhejiang Province, China
| | - Zhi-Li Zhang
- Department of Otorhinolaryngology Head and Neck Surgery, The First Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou 310003, Zhejiang Province, China
| | - Yong Fu
- Department of Otorhinolaryngology Head and Neck Surgery, The Children’s Hospital, Zhejiang University School of Medicine, Hangzhou 310009, Zhejiang Province, China
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Manyisa N, Adadey SM, Wonkam-Tingang E, Yalcouye A, Wonkam A. Hearing Impairment in South Africa and the Lessons Learned for Planetary Health Genomics: A Systematic Review. OMICS : A JOURNAL OF INTEGRATIVE BIOLOGY 2022; 26:2-18. [PMID: 35041532 PMCID: PMC8792495 DOI: 10.1089/omi.2021.0181] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Hearing impairment (HI) is a silent planetary health crisis that requires attention worldwide. The prevalence of HI in South Africa is estimated as 5.5 in 100 live births, which is about 5 times higher than the prevalence in high-income countries. This also offers opportunity to drive progressive science, technology and innovation policy, and health systems. We present here a systematic analysis and review on the prevalence, etiologies, clinical patterns, and genetics/genomics of HI in South Africa. We searched PubMed, Scopus, African Journals Online, AFROLIB, and African Index Medicus to identify the pertinent studies on HI in South Africa, published from inception to April 30, 2021, and the data were summarized narratively. We screened 944 records, of which 27 studies were included in the review. The age at diagnosis is ∼3 years of age and the most common factor associated with acquired HI was middle ear infections. There were numerous reports on medication toxicity, with kanamycin-induced ototoxicity requiring specific attention when considering the high burden of tuberculosis in South Africa. The Waardenburg Syndrome is the most common reported syndromic HI. The Usher Syndrome is the only syndrome with genetic investigations, whereby a founder mutation was identified among black South Africans (MYO7A-c.6377delC). GJB2 and GJB6 genes are not major contributors to nonsyndromic HI among Black South Africans. Furthermore, emerging data using targeted panel sequencing have shown a low resolution rate in Black South Africans in known HI genes. Importantly, mutations in known nonsyndromic HI genes are infrequent in South Africa. Therefore, whole-exome sequencing appears as the most effective way forward to identify variants associated with HI in South Africa. Taken together, this article contributes to the emerging field of planetary health genomics with a focus on HI and offers new insights and lessons learned for future roadmaps on genomics/multiomics and clinical studies of HI around the world.
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Affiliation(s)
- Noluthando Manyisa
- Division of Human Genetics, Department of Pathology, Institute of Infectious Disease and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Samuel Mawuli Adadey
- Division of Human Genetics, Department of Pathology, Institute of Infectious Disease and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa.,West African Centre for Cell Biology of Infectious Pathogens, College of Basic and Applied Sciences, University of Ghana, Accra, Ghana
| | - Edmond Wonkam-Tingang
- Division of Human Genetics, Department of Pathology, Institute of Infectious Disease and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Abdoulaye Yalcouye
- Division of Human Genetics, Department of Pathology, Institute of Infectious Disease and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa.,Department of Neurology, Point G Teaching Hospital, University of Sciences, Techniques and Technology, Bamako, Mali
| | - Ambroise Wonkam
- Division of Human Genetics, Department of Pathology, Institute of Infectious Disease and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
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Laird DW, Lampe PD. Cellular mechanisms of connexin-based inherited diseases. Trends Cell Biol 2022; 32:58-69. [PMID: 34429228 PMCID: PMC8688313 DOI: 10.1016/j.tcb.2021.07.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Revised: 07/22/2021] [Accepted: 07/26/2021] [Indexed: 01/03/2023]
Abstract
The 21-member connexin gene family exhibits distinct tissue expression patterns that can cause a diverse array of over 30 inherited connexin-linked diseases ranging from deafness to skin defects and blindness. Intriguingly, germline mutations can cause disease in one tissue while other tissues that abundantly express the mutant connexin remain disease free, highlighting the importance of the cellular context of mutant expression. Modeling connexin pathologies in genetically modified mice and tissue-relevant cells has informed extensively on no less than a dozen gain- and loss-of-function mechanisms that underpin disease. This review focuses on how a deeper molecular understanding of the over 930 mutations in 11 connexin-encoding genes is foundational for creating a framework for therapeutic interventions.
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Affiliation(s)
- Dale W. Laird
- Departments of Anatomy and Cell Biology, and Physiology and Pharmacology, University of Western Ontario, London, ON, CANADA
| | - Paul D. Lampe
- Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
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68
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Zhao HB, Liu LM, Yu N, Zhu Y, Mei L, Chen J, Liang C. Efferent neurons control hearing sensitivity and protect hearing from noise through the regulation of gap junctions between cochlear supporting cells. J Neurophysiol 2022; 127:313-327. [PMID: 34907797 PMCID: PMC8759971 DOI: 10.1152/jn.00468.2021] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
It is critical for hearing that the descending cochlear efferent system provides a negative feedback to hair cells to regulate hearing sensitivity and protect hearing from noise. The medial olivocochlear (MOC) efferent nerves project to outer hair cells (OHCs) to regulate OHC electromotility, which is an active cochlear amplifier and can increase hearing sensitivity. Here, we report that the MOC efferent nerves also could innervate supporting cells (SCs) in the vicinity of OHCs to regulate hearing sensitivity. MOC nerve fibers are cholinergic, and acetylcholine (ACh) is a primary neurotransmitter. Immunofluorescent staining showed that MOC nerve endings, presynaptic vesicular acetylcholine transporters (VAChTs), and postsynaptic ACh receptors were visible at SCs and in the SC area. Application of ACh in SCs could evoke a typical inward current and reduce gap junctions (GJs) between them, which consequently enhanced the direct effect of ACh on OHCs to shift but not eliminate OHC electromotility. This indirect, GJ-mediated inhibition had a long-lasting influence. In vivo experiments further demonstrated that deficiency of this GJ-mediated efferent pathway decreased the regulation of active cochlear amplification and compromised the protection against noise. In particular, distortion product otoacoustic emission (DPOAE) showed a delayed reduction after noise exposure. Our findings reveal a new pathway for the MOC efferent system via innervating SCs to control active cochlear amplification and hearing sensitivity. These data also suggest that this SC GJ-mediated efferent pathway may play a critical role in long-term efferent inhibition and is required for protection of hearing from noise trauma.NEW & NOTEWORTHY The cochlear efferent system provides a negative feedback to control hair cell activity and hearing sensitivity and plays a critical role in noise protection. We reveal a new efferent control pathway in which medial olivocochlear efferent fibers have innervations with cochlear supporting cells to control their gap junctions, therefore regulating outer hair cell electromotility and hearing sensitivity. This supporting cell gap junction-mediated efferent control pathway is required for the protection of hearing from noise.
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69
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Preimplantation Genetic Diagnosis in Hereditary Hearing Impairment. Diagnostics (Basel) 2021; 11:diagnostics11122395. [PMID: 34943631 PMCID: PMC8700639 DOI: 10.3390/diagnostics11122395] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2021] [Revised: 12/16/2021] [Accepted: 12/16/2021] [Indexed: 01/19/2023] Open
Abstract
Sensorineural hearing impairment is a common sensory deficit in children and more than 50% of these cases are caused by genetic etiologies, that is, hereditary hearing impairment (HHI). Recent advances in genomic medicine have revolutionized the diagnostics of, and counseling for, HHI, including preimplantation genetic diagnosis (PGD), thus providing parents-to-be with better reproductive choices. Over the past decade, we have performed PGD using the amplification refractory mutation system quantitative polymerase chain reaction (ARMS-qPCR) technique in 11 couples with a history of HHI, namely eight with GJB2 variants, one with OTOF variants, one with SLC26A4 variants, and one with an MITF variant. We demonstrated that PGD can be successfully applied to HHI of different inheritance modes, namely autosomal dominant or recessive, and phenotypes, namely syndromic or non-syndromic HHI. However, certain ethical concerns warrant scrutiny before PGD can be widely applied to at-risk couples with a history of HHI.
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A common founder effect of the splice site variant c.-23 + 1G > A in GJB2 gene causing autosomal recessive deafness 1A (DFNB1A) in Eurasia. Hum Genet 2021; 141:697-707. [PMID: 34839402 DOI: 10.1007/s00439-021-02405-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Accepted: 11/21/2021] [Indexed: 10/19/2022]
Abstract
Mutations in the GJB2 gene are known to be a major cause of autosomal recessive deafness 1A (OMIM 220290). The most common pathogenic variants of the GJB2 gene have a high ethno-geographic specificity in their distribution, being attributed to a founder effect related to the Neolithic migration routes of Homo sapiens. The c.-23 + 1G > A splice site variant is frequently found among deaf patients of both Caucasian and Asian origins. It is currently unknown whether the spread of this mutation across Eurasia is a result of the founder effect or if it could have multiple local centers of origin. To determine the origin of c.-23 + 1G > A, we reconstructed haplotypes by genotyping SNPs on an Illumina OmniExpress 730 K platform of 23 deaf individuals homozygous for this variant from different populations of Eurasia. The analyses revealed the presence of common regions of homozygosity in different individual genomes in the sample. These data support the hypothesis of the common founder effect in the distribution of the c.-23 + 1G > A variant of the GJB2 gene. Based on the published data on the c.-23 + 1G > A prevalence among 16,177 deaf people and the calculation of the TMRCA of the modified f2-haplotypes carrying this variant, we reconstructed the potential migration routes of the carriers of this mutation around the world. This analysis indicates that the c.-23 + 1G > A variant in the GJB2 gene may have originated approximately 6000 years ago in the territory of the Caucasus or the Middle East then spread throughout Europe, South and Central Asia and other regions of the world.
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Diagnostic Yield of Targeted Hearing Loss Gene Panel Sequencing in a Large German Cohort With a Balanced Age Distribution from a Single Diagnostic Center: An Eight-year Study. Ear Hear 2021; 43:1049-1066. [PMID: 34753855 PMCID: PMC9007094 DOI: 10.1097/aud.0000000000001159] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Objectives: Hereditary hearing loss exhibits high degrees of genetic and clinical heterogeneity. To elucidate the population-specific and age-related genetic and clinical spectra of hereditary hearing loss, we investigated the sequencing data of causally associated hearing loss genes in a large cohort of hearing-impaired probands with a balanced age distribution from a single center in Southwest Germany. Design: Genetic testing was applied to 305 hearing-impaired probands/families with a suspected genetic hearing loss etiology and a balanced age distribution over a period of 8 years (2011–2018). These individuals were representative of the regional population according to age and sex distributions. The genetic testing workflow consisted of single-gene screening (n = 21) and custom-designed hearing loss gene panel sequencing (n = 284) targeting known nonsyndromic and syndromic hearing loss genes in a diagnostic setup. Retrospective reanalysis of sequencing data was conducted by applying the current American College of Medical Genetics and Genomics/Association for Molecular Pathology guidelines. Results: A genetic diagnosis was established for 75 (25%) of the probands that involved 75 causal variants in 35 genes, including 16 novel causal variants and 9 medically significant variant reclassifications. Nearly half of the solved cases (47%; n = 35) were related to variants in the five most frequently affected genes: GJB2 (25%), MYO15A, WFS1, SLC26A4, and COL11A1 (all 5%). Nearly one-quarter of the cases (23%; n = 17) were associated with variants in seven additional genes (TMPRSS3, COL4A3, LOXHD1, EDNRB, MYO6, TECTA, and USH2A). The remaining one-third of single cases (33%; n = 25) were linked to variants in 25 distinct genes. Diagnostic rates and gene distribution were highly dependent on phenotypic characteristics. A positive family history of autosomal-recessive inheritance in combination with early onset and higher grades of hearing loss significantly increased the solve rate up to 60%, while late onset and lower grades of hearing loss yielded significantly fewer diagnoses. Regarding genetic diagnoses, autosomal-dominant genes accounted for 37%, autosomal-recessive genes for 60%, and X-linked genes for 3% of the solved cases. Syndromic/nonsyndromic hearing loss mimic genes were affected in 27% of the genetic diagnoses. Conclusions: The genetic epidemiology of the largest German cohort subjected to comprehensive targeted sequencing for hereditary hearing loss to date revealed broad causal gene and variant spectra in this population. Targeted hearing loss gene panel analysis proved to be an effective tool for ensuring an appropriate diagnostic yield in a routine clinical setting including the identification of novel variants and medically significant reclassifications. Solve rates were highly sensitive to phenotypic characteristics. The unique population-adapted and balanced age distribution of the cohort favoring late hearing loss onset uncovered a markedly large contribution of autosomal-dominant genes to the diagnoses which may be a representative for other age balanced cohorts in other populations.
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A Monoallelic Variant in REST Is Associated with Non-Syndromic Autosomal Dominant Hearing Impairment in a South African Family. Genes (Basel) 2021; 12:genes12111765. [PMID: 34828371 PMCID: PMC8618167 DOI: 10.3390/genes12111765] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Revised: 10/31/2021] [Accepted: 11/02/2021] [Indexed: 01/03/2023] Open
Abstract
Hearing impairment (HI) is a sensory disorder with a prevalence of 0.0055 live births in South Africa. DNA samples from a South African family presenting with progressive, autosomal dominant non-syndromic HI were subjected to whole-exome sequencing, and a novel monoallelic variant in REST [c.1244GC; p.(C415S)], was identified as the putative causative variant. The co-segregation of the variant was confirmed with Sanger Sequencing. The variant is absent from databases, 103 healthy South African controls, and 52 South African probands with isolated HI. In silico analysis indicates that the p.C415S variant in REST substitutes a conserved cysteine and results in changes to the surrounding secondary structure and the disulphide bonds, culminating in alteration of the tertiary structure of REST. Localization studies using ectopically expressed GFP-tagged Wild type (WT) and mutant REST in HEK-293 cells show that WT REST localizes exclusively to the nucleus; however, the mutant protein localizes throughout the cell. Additionally, mutant REST has an impaired ability to repress its known target AF1q. The data demonstrates that the identified mutation compromises the function of REST and support its implication in HI. This study is the second report, worldwide, to implicate REST in HI and suggests that it should be included in diagnostic HI panels.
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73
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Adadey SM, Wonkam-Tingang E, Aboagye ET, Quaye O, Awandare GA, Wonkam A. Hearing loss in Africa: current genetic profile. Hum Genet 2021; 141:505-517. [PMID: 34609590 PMCID: PMC9034983 DOI: 10.1007/s00439-021-02376-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Accepted: 09/21/2021] [Indexed: 01/03/2023]
Abstract
Hearing impairment (HI) is highly heterogeneous with over 123 associated genes reported to date, mostly from studies among Europeans and Asians. Here, we performed a systematic review of literature on the genetic profile of HI in Africa. The study protocol was registered on PROSPERO, International Prospective Register of Systematic Reviews with the registration number “CRD42021240852”. Literature search was conducted on PubMed, Scopus, Africa-Wide Information, and Web of Science databases. A total of 89 full-text records was selected and retrieved for data extraction and analyses. We found reports from only 17/54 (31.5%) African countries. The majority (61/89; 68.5%) of articles were from North Africa, with few reports found from sub-Saharan Africa. The most common method used in these publications was targeted gene sequencing (n = 66/111; 59.5%), and only 13.5% (n = 15/111) used whole-exome sequencing. More than half of the studies were performed in families segregating HI (n = 51/89). GJB2 was the most investigated gene, with GJB2: p.(R143W) founder variant only reported in Ghana, while GJB2: c.35delG was common in North African countries. Variants in MYO15A were the second frequently reported in both North and Central Africa, followed by ATP6V1B1 only reported from North Africa. Usher syndrome was the main syndromic HI molecularly investigated, with variants in five genes reported: USH2A, USH1G, USH1C, MYO7A, and PCDH15. MYO7A: p.(P1780S) founder variant was reported as the common Usher syndrome variant among Black South Africans. This review provides the most comprehensive data on HI gene variants in the largely under-investigated African populations. Future exomes studies particularly in multiplex families will likely provide opportunities for the discovery of the next sets of novel HI genes, and well as unreported variants in known genes to further our understanding of HI pathobiology, globally.
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Affiliation(s)
- Samuel Mawuli Adadey
- Department of Biochemistry, Cell and Molecular Biology, West African Centre for Cell Biology of Infectious Pathogens (WACCBIP), University of Ghana, P.O. Box LG 54, Legon, Accra, Ghana.,Division of Human Genetics, Faculty of Health Sciences, University of Cape Town, Anzio Road, Observatory, Cape Town, 7925, South Africa
| | - Edmond Wonkam-Tingang
- Division of Human Genetics, Faculty of Health Sciences, University of Cape Town, Anzio Road, Observatory, Cape Town, 7925, South Africa
| | - Elvis Twumasi Aboagye
- Department of Biochemistry, Cell and Molecular Biology, West African Centre for Cell Biology of Infectious Pathogens (WACCBIP), University of Ghana, P.O. Box LG 54, Legon, Accra, Ghana
| | - Osbourne Quaye
- Department of Biochemistry, Cell and Molecular Biology, West African Centre for Cell Biology of Infectious Pathogens (WACCBIP), University of Ghana, P.O. Box LG 54, Legon, Accra, Ghana
| | - Gordon A Awandare
- Department of Biochemistry, Cell and Molecular Biology, West African Centre for Cell Biology of Infectious Pathogens (WACCBIP), University of Ghana, P.O. Box LG 54, Legon, Accra, Ghana
| | - Ambroise Wonkam
- Division of Human Genetics, Faculty of Health Sciences, University of Cape Town, Anzio Road, Observatory, Cape Town, 7925, South Africa.
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Hosoya M, Fujioka M, Nara K, Morimoto N, Masuda S, Sugiuchi T, Katsunuma S, Takagi A, Morita N, Ogawa K, Kaga K, Matsunaga T. Investigation of the hearing levels of siblings affected by a single GJB2 variant: Possibility of genetic modifiers. Int J Pediatr Otorhinolaryngol 2021; 149:110840. [PMID: 34293626 DOI: 10.1016/j.ijporl.2021.110840] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Revised: 05/25/2021] [Accepted: 07/11/2021] [Indexed: 11/25/2022]
Abstract
OBJECTIVE Variants in GJB2 can cause autosomal recessive deafness (DFNB1). There is evidence for genotype-phenotype correlations of GJB2 variants; however, several genotypes can cause varying levels of hearing loss likely attributable to differences in genetic or environmental background. As siblings share approximately 50% of their genetic background and usually have a common environmental background, analysis of phenotypes of siblings with a specific GJB2 variant may reveal factors relevant to phenotypic variation. There have been no previous analyses of differences in hearing among siblings carrying a single GJB2 genotype. Here, we investigated hearing differences between siblings with a single GJB2 variant, which can cause various levels of hearing loss. METHODS We examined hearing levels in 16 pairs of siblings homozygous for the c.235delC variant of GJB2. Differences in hearing acuity between sibling pairs were detected by auditory evaluation. RESULTS Average differences in acoustic threshold >30 dB were observed between five pairs of siblings, whereas the remaining 11 pairs had average threshold values within approximately 10 dB of one another. Hearing loss varied from moderate to profound. CONCLUSION Our results indicate that auditory acuity associated with homozygosity for GJB2 c.235delC can vary in degree; however, in approximately 70% of younger siblings, it was approximately the same as that in the first child, despite a diverse spectrum of hearing loss among different families. These results suggest that differences in genetic background may modify the phenotype associated with homozygous GJB2 c.235delC.
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Affiliation(s)
- Makoto Hosoya
- Department of Otorhinolaryngology, Head and Neck Surgery, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan
| | - Masato Fujioka
- Department of Otorhinolaryngology, Head and Neck Surgery, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan
| | - Kiyomitsu Nara
- Division of Hearing and Balance Research, National Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center, 2-5-1 Higashigaoka, Meguro-ku, Tokyo, 152-8902, Japan
| | - Noriko Morimoto
- Department of Otorhinolaryngology, National Center for Child Health and Development, 2-10-1 Okura, Setagaya-ku, Tokyo, 157-8535, Japan
| | - Sawako Masuda
- Department of Otorhinolaryngology, National Hospital Organization Mie National Hospital, 357 Osato-Kubota, Tsu, Mie, 514-0125, Japan
| | - Tomoko Sugiuchi
- Department of Otorhinolaryngology, Kanto Rosai Hospital, 1-1 Kizukisumiyoshi-cho, Nakahara-ku, Kawasaki-shi, Kanagawa, 211-8510, Japan
| | - Sayaka Katsunuma
- Department of Otorhinolaryngology, Hyogo Prefectural Kobe Children's Hospital, 1-6-7 Minatojima-minamimachi, Chuo-ku, Kobe-shi, Hyogo, 650-0047, Japan
| | - Akira Takagi
- Department of Otorhinolaryngology, Shizuoka General Hospital, 4-27-1 Kita Ando Aoi-ku, Shizuoka-shi, Shizuoka, 420-8527, Japan
| | - Noriko Morita
- Department of Otorhinolaryngology, Teikyo University Hospital, 2-11-1 Kaga, Itabashi-Ku, Tokyo, 173-8606, Japan; Department of Otorhinolaryngology, Kobari General Hospital, 29-1 Yokouchi, Noda, Chiba, 278-8501, Japan
| | - Kaoru Ogawa
- Department of Otorhinolaryngology, Head and Neck Surgery, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan
| | - Kimitaka Kaga
- Division of Hearing and Balance Research, National Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center, 2-5-1 Higashigaoka, Meguro-ku, Tokyo, 152-8902, Japan
| | - Tatsuo Matsunaga
- Division of Hearing and Balance Research, National Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center, 2-5-1 Higashigaoka, Meguro-ku, Tokyo, 152-8902, Japan; Medical Genetics Center, National Hospital Organization Tokyo Medical Center, 2-5-1 Higashigaoka, Meguro-ku, Tokyo, 152-8902, Japan.
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75
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Batissoco AC, Pedroso-Campos V, Pardono E, Sampaio-Silva J, Sonoda CY, Vieira-Silva GA, da Silva de Oliveira Longati EU, Mariano D, Hoshino ACH, Tsuji RK, Jesus-Santos R, Abath-Neto O, Bento RF, Oiticica J, Lezirovitz K. Molecular and genetic characterization of a large Brazilian cohort presenting hearing loss. Hum Genet 2021; 141:519-538. [PMID: 34599368 DOI: 10.1007/s00439-021-02372-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Accepted: 09/15/2021] [Indexed: 12/16/2022]
Abstract
Hearing loss is one of the most common sensory defects, affecting 5.5% of the worldwide population and significantly impacting health and social life. It is mainly attributed to genetic causes, but their relative contribution reflects the geographical region's socio-economic development. Extreme genetic heterogeneity with hundreds of deafness genes involved poses challenges for molecular diagnosis. Here we report the investigation of 542 hearing-impaired subjects from all Brazilian regions to search for genetic causes. Biallelic GJB2/GJB6 causative variants were identified in 12.9% (the lowest frequency was found in the Northern region, 7.7%), 0.4% carried GJB2 dominant variants, and 0.6% had the m.1555A > G variant (one aminoglycoside-related). In addition, other genetic screenings, employed in selected probands according to clinical presentation and presumptive inheritance patterns, identified causative variants in 2.4%. Ear malformations and auditory neuropathy were diagnosed in 10.8% and 3.5% of probands, respectively. In 3.8% of prelingual/perilingual cases, Waardenburg syndrome was clinically diagnosed, and in 71.4%, these diagnoses were confirmed with pathogenic variants revealed; seven out of them were novel, including one CNV. All these genetic screening strategies revealed causative variants in 16.2% of the cases. Based on causative variants in the molecular diagnosis and genealogy analyses, a probable genetic etiology was found in ~ 50% of the cases. The present study highlights the relevance of GJB2/GJB6 as a cause of hearing loss in all Brazilian regions and the importance of screening unselected samples for estimating frequencies. Moreover, when a comprehensive screening is not available, molecular diagnosis can be enhanced by selecting probands for specific screenings.
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Affiliation(s)
- Ana Carla Batissoco
- Laboratório de Otorrinolaringologia/LIM 32, Hospital das Clínicas HCFMUSP, Faculdade de Medicina, Universidade de São Paulo, São Paulo, SP, Brasil
- ENT Department, Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, São Paulo, SP, Brasil
| | - Vinicius Pedroso-Campos
- Laboratório de Otorrinolaringologia/LIM 32, Hospital das Clínicas HCFMUSP, Faculdade de Medicina, Universidade de São Paulo, São Paulo, SP, Brasil
| | - Eliete Pardono
- Laboratório de Otorrinolaringologia/LIM 32, Hospital das Clínicas HCFMUSP, Faculdade de Medicina, Universidade de São Paulo, São Paulo, SP, Brasil
- Instituto de Ciências de Saúde da UNIP, São Paulo, SP, Brasil
| | - Juliana Sampaio-Silva
- Laboratório de Otorrinolaringologia/LIM 32, Hospital das Clínicas HCFMUSP, Faculdade de Medicina, Universidade de São Paulo, São Paulo, SP, Brasil
| | - Cindy Yukimi Sonoda
- Laboratório de Otorrinolaringologia/LIM 32, Hospital das Clínicas HCFMUSP, Faculdade de Medicina, Universidade de São Paulo, São Paulo, SP, Brasil
| | - Gleiciele Alice Vieira-Silva
- Laboratório de Otorrinolaringologia/LIM 32, Hospital das Clínicas HCFMUSP, Faculdade de Medicina, Universidade de São Paulo, São Paulo, SP, Brasil
| | | | - Diego Mariano
- Department of Computer Science, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brasil
| | - Ana Cristina Hiromi Hoshino
- ENT Department, Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, São Paulo, SP, Brasil
| | - Robinson Koji Tsuji
- ENT Department, Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, São Paulo, SP, Brasil
| | - Rafaela Jesus-Santos
- Laboratório de Otorrinolaringologia/LIM 32, Hospital das Clínicas HCFMUSP, Faculdade de Medicina, Universidade de São Paulo, São Paulo, SP, Brasil
| | - Osório Abath-Neto
- Departamento de Neurologia, Faculdade de Medicina FMUSP, Universidade de São Paulo, São Paulo, SP, Brasil
| | - Ricardo Ferreira Bento
- Laboratório de Otorrinolaringologia/LIM 32, Hospital das Clínicas HCFMUSP, Faculdade de Medicina, Universidade de São Paulo, São Paulo, SP, Brasil
- ENT Department, Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, São Paulo, SP, Brasil
| | - Jeanne Oiticica
- Laboratório de Otorrinolaringologia/LIM 32, Hospital das Clínicas HCFMUSP, Faculdade de Medicina, Universidade de São Paulo, São Paulo, SP, Brasil
- ENT Department, Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, São Paulo, SP, Brasil
| | - Karina Lezirovitz
- Laboratório de Otorrinolaringologia/LIM 32, Hospital das Clínicas HCFMUSP, Faculdade de Medicina, Universidade de São Paulo, São Paulo, SP, Brasil.
- ENT Department, Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, São Paulo, SP, Brasil.
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76
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Lin L, Zhang D, Jin Q, Teng Y, Yao X, Zhao T, Xu X, Jin Y. Mutational Analysis of Mitochondrial tRNA Genes in 200 Patients with Type 2 Diabetes Mellitus. Int J Gen Med 2021; 14:5719-5735. [PMID: 34557026 PMCID: PMC8454214 DOI: 10.2147/ijgm.s330973] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Accepted: 08/25/2021] [Indexed: 12/12/2022] Open
Abstract
Objective Previous studies showed that variants in mitochondrial DNA (mtDNA) are associated with type 2 diabetes mellitus (T2DM). However, the relationships between mitochondrial tRNA (mt-tRNA) variants and T2DM remain poorly understood. Methods In this study, we performed a mutational screening of 22 mt-tRNA genes in a cohort of 200 Han Chinese subjects with T2DM and 200 control subjects through PCR–Sanger sequencing. The identified mt-tRNA variants were assessed for their pathogenicity via the phylogenetic approach, structural and functional analysis. Furthermore, two Han Chinese pedigrees with maternally inherited diabetes and deafness (MIDD) were reported by clinical and genetic assessments. Results A total of 49 genetic variants in mt-tRNA genes were identified; among them, 31 variants (17 pathogenic/likely pathogenic) were absent in controls, located at extremely conserved nucleotides, may have potential structural and functional significance, thereby considered to be T2DM-associated variants. In addition, sequence analysis of entire mitochondrial genomes of the matrilineal relatives from two MIDD pedigrees revealed the occurrence of tRNALeu(UUR) A3243G and T3290C mutations, as well as sets of polymorphisms belonging to mitochondrial haplogroups F2 and D4. However, the lack of any functional variants in connexin 26 gene (GJB2) and tRNA 5-methylaminomethyl-2-thiouridylate (TRMU) suggested that nuclear genes may not play active roles in clinical expression of MIDD in these pedigrees. Conclusion Our data indicated that mt-tRNA variants were associated with T2DM, screening for mt-tRNA pathogenic mutations was recommended for early detection and prevention of mitochondrial diabetes.
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Affiliation(s)
- Liangyan Lin
- Department of Endocrinology and Metabolism, Yantai Affiliated Hospital of Binzhou Medical University, Yantai, Shandong, People's Republic of China
| | - Dongdong Zhang
- Department of Endocrinology and Metabolism, Yantai Affiliated Hospital of Binzhou Medical University, Yantai, Shandong, People's Republic of China
| | - Qingsong Jin
- Department of Endocrinology and Metabolism, Yantai Affiliated Hospital of Binzhou Medical University, Yantai, Shandong, People's Republic of China
| | - Yaqin Teng
- Department of Endocrinology and Metabolism, Yantai Affiliated Hospital of Binzhou Medical University, Yantai, Shandong, People's Republic of China
| | - Xiaoyan Yao
- Department of Endocrinology and Metabolism, Yantai Affiliated Hospital of Binzhou Medical University, Yantai, Shandong, People's Republic of China
| | - Tiantian Zhao
- Department of Endocrinology and Metabolism, Yantai Affiliated Hospital of Binzhou Medical University, Yantai, Shandong, People's Republic of China
| | - Xinmiao Xu
- Department of Endocrinology, Yantai Yeda Hospital, Yantai, Shandong, People's Republic of China
| | - Yongjun Jin
- Department of Endocrinology and Metabolism, Yantai Affiliated Hospital of Binzhou Medical University, Yantai, Shandong, People's Republic of China
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77
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Florentine MM, Rouse SL, Stephans J, Conrad D, Czechowicz J, Matthews IR, Meyer AK, Nadaraja GS, Parikh R, Virbalas J, Weinstein JE, Chan DK. Racial and ethnic disparities in diagnostic efficacy of comprehensive genetic testing for sensorineural hearing loss. Hum Genet 2021; 141:495-504. [PMID: 34515852 PMCID: PMC9035005 DOI: 10.1007/s00439-021-02338-4] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Accepted: 08/09/2021] [Indexed: 11/25/2022]
Abstract
Understanding racial and ethnic disparities in diagnostic rates of genetic testing is critical for health equity. We sought to understand the extent and cause of racial and ethnic disparities in diagnostic efficacy of comprehensive genetic testing (CGT) for sensorineural hearing loss (SNHL). We performed a retrospective cohort study at two tertiary children’s hospitals on a diverse cohort of 240 consecutive pediatric patients (76% publicly insured, 82% non-White) with SNHL of unknown etiology who underwent CGT. Definite and possible genetic diagnoses were assigned for each patient, representing the likelihood of a genetic cause of hearing loss. Associations between diagnostic rates were examined. 3.8 ± 2.1 variants were detected per patient; this frequency did not vary between White/Asian and Hispanic/Black cohorts. Overall, 82% of variants were variants of uncertain significance (VUS). Compared with White and Asian subjects, variants identified among Hispanic and Black children were less likely to be classified as pathogenic/likely pathogenic (15% vs. 24%, p < 0.001), and Hispanic and Black children were less likely to have a definite genetic diagnosis (10% vs. 37%, p < 0.001). The adjusted odds ratio for definite genetic diagnosis in Black and Hispanic children compared with White and Asian children was 0.19. Expanding genetic diagnostic criteria to include predicted deleterious VUSs reduced these disparities between White/Asian and Hispanic/Black children, with comparable molecular diagnostic rates (41% vs. 38%, p = 0.72). However, in silico predictions are insufficiently valid for clinical use. Increased inclusion of underrepresented groups in genetic hearing-loss studies to clinically validate these variants is necessary to reduce racial and ethnic disparities in diagnostic efficacy of comprehensive genetic testing.
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Affiliation(s)
- Michelle M Florentine
- Department of Otolaryngology-Head and Neck Surgery, University of California-San Francisco, 2233 Post Street, Third Floor, San Francisco, CA, 94115, USA.,Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Stephanie L Rouse
- Department of Otolaryngology-Head and Neck Surgery, University of California-San Francisco, 2233 Post Street, Third Floor, San Francisco, CA, 94115, USA
| | - Jihyun Stephans
- Department of Otolaryngology-Head and Neck Surgery, University of California-San Francisco, 2233 Post Street, Third Floor, San Francisco, CA, 94115, USA.,Division of Pediatric Otolaryngology-Head and Neck Surgery, University of California-San Francisco, 2233 Post Street, Third Floor, San Francisco, CA, 94115, USA
| | - David Conrad
- Department of Otolaryngology-Head and Neck Surgery, University of California-San Francisco, 2233 Post Street, Third Floor, San Francisco, CA, 94115, USA.,Division of Pediatric Otolaryngology-Head and Neck Surgery, University of California-San Francisco, 2233 Post Street, Third Floor, San Francisco, CA, 94115, USA
| | - Josephine Czechowicz
- Department of Otolaryngology-Head and Neck Surgery, University of California-San Francisco, 2233 Post Street, Third Floor, San Francisco, CA, 94115, USA.,Division of Pediatric Otolaryngology-Head and Neck Surgery, University of California-San Francisco, 2233 Post Street, Third Floor, San Francisco, CA, 94115, USA
| | - Ian R Matthews
- Department of Otolaryngology-Head and Neck Surgery, University of California-San Francisco, 2233 Post Street, Third Floor, San Francisco, CA, 94115, USA
| | - Anna K Meyer
- Department of Otolaryngology-Head and Neck Surgery, University of California-San Francisco, 2233 Post Street, Third Floor, San Francisco, CA, 94115, USA.,Division of Pediatric Otolaryngology-Head and Neck Surgery, University of California-San Francisco, 2233 Post Street, Third Floor, San Francisco, CA, 94115, USA
| | - Garani S Nadaraja
- Department of Otolaryngology-Head and Neck Surgery, University of California-San Francisco, 2233 Post Street, Third Floor, San Francisco, CA, 94115, USA.,Division of Pediatric Otolaryngology-Head and Neck Surgery, University of California-San Francisco, 2233 Post Street, Third Floor, San Francisco, CA, 94115, USA
| | - Rajan Parikh
- Department of Otolaryngology-Head and Neck Surgery, University of California-San Francisco, 2233 Post Street, Third Floor, San Francisco, CA, 94115, USA
| | - Jordan Virbalas
- Department of Otolaryngology-Head and Neck Surgery, University of California-San Francisco, 2233 Post Street, Third Floor, San Francisco, CA, 94115, USA.,Division of Pediatric Otolaryngology-Head and Neck Surgery, University of California-San Francisco, 2233 Post Street, Third Floor, San Francisco, CA, 94115, USA
| | - Jacqueline E Weinstein
- Department of Otolaryngology-Head and Neck Surgery, University of California-San Francisco, 2233 Post Street, Third Floor, San Francisco, CA, 94115, USA.,Division of Pediatric Otolaryngology-Head and Neck Surgery, University of California-San Francisco, 2233 Post Street, Third Floor, San Francisco, CA, 94115, USA
| | - Dylan K Chan
- Department of Otolaryngology-Head and Neck Surgery, University of California-San Francisco, 2233 Post Street, Third Floor, San Francisco, CA, 94115, USA. .,Division of Pediatric Otolaryngology-Head and Neck Surgery, University of California-San Francisco, 2233 Post Street, Third Floor, San Francisco, CA, 94115, USA.
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78
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Brewer CC, King KA. Genetic hearing loss: the audiologist's perspective. Hum Genet 2021; 141:311-314. [PMID: 34480642 DOI: 10.1007/s00439-021-02360-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Accepted: 08/29/2021] [Indexed: 10/20/2022]
Abstract
As knowledge regarding the genetic underpinnings of hearing loss has rapidly evolved, the role of the clinician in managing the patient has expanded beyond that of defining the characteristics of the auditory phenotype. The importance and impact of a genetic diagnosis has yet to be fully realized in routine clinical care. However, audiologists are uniquely situated to be front-line healthcare providers for persons of all ages with hereditary hearing loss. Here, we discuss why the combination of genotype and phenotype are necessary for the delivery of personalized and effective clinical care for individuals with genetic hearing loss.
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Affiliation(s)
- Carmen C Brewer
- National Institute on Deafness and Other Communication Disorders, National Institutes of Health, 10 Center Drive, 5C422, Bethesda, MD, 20892, USA.
| | - Kelly A King
- National Institute on Deafness and Other Communication Disorders, National Institutes of Health, 10 Center Drive, 5C422, Bethesda, MD, 20892, USA
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Van Heurck R, Carminho-Rodrigues MT, Ranza E, Stafuzza C, Quteineh L, Gehrig C, Hammar E, Guipponi M, Abramowicz M, Senn P, Guinand N, Cao-Van H, Paoloni-Giacobino A. Benefits of Exome Sequencing in Children with Suspected Isolated Hearing Loss. Genes (Basel) 2021; 12:genes12081277. [PMID: 34440452 PMCID: PMC8391342 DOI: 10.3390/genes12081277] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Revised: 08/03/2021] [Accepted: 08/18/2021] [Indexed: 12/12/2022] Open
Abstract
Purpose: Hearing loss is characterized by an extensive genetic heterogeneity and remains a common disorder in children. Molecular diagnosis is of particular benefit in children, and permits the early identification of clinically-unrecognized hearing loss syndromes, which permits effective clinical management and follow-up, including genetic counselling. Methods: We performed whole-exome sequencing with the analysis of a panel of 189 genes associated with hearing loss in a prospective cohort of 61 children and 9 adults presenting mainly with isolated hearing loss. Results: The overall diagnostic rate using exome sequencing was 47.2% (52.5% in children; 22% in adults). In children with confirmed molecular results, 17/32 (53.2%) showed autosomal recessive inheritance patterns, 14/32 (43.75%) showed an autosomal dominant condition, and one case had X-linked hearing loss. In adults, the two patients showed an autosomal dominant inheritance pattern. Among the 32 children, 17 (53.1%) had nonsyndromic hearing loss and 15 (46.7%) had syndromic hearing loss. One adult was diagnosed with syndromic hearing loss and one with nonsyndromic hearing loss. The most common causative genes were STRC (5 cases), GJB2 (3 cases), COL11A1 (3 cases), and ACTG1 (3 cases). Conclusions: Exome sequencing has a high diagnostic yield in children with hearing loss and can reveal a syndromic hearing loss form before other organs/systems become involved, allowing the surveillance of unrecognized present and/or future complications associated with these syndromes.
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Affiliation(s)
- Roxane Van Heurck
- Division of Genetic Medicine, Geneva University Hospitals, 1205 Geneva, Switzerland; (R.V.H.); (M.T.C.-R.); (E.R.); (L.Q.); (C.G.); (E.H.); (M.G.); (M.A.)
| | - Maria Teresa Carminho-Rodrigues
- Division of Genetic Medicine, Geneva University Hospitals, 1205 Geneva, Switzerland; (R.V.H.); (M.T.C.-R.); (E.R.); (L.Q.); (C.G.); (E.H.); (M.G.); (M.A.)
| | - Emmanuelle Ranza
- Division of Genetic Medicine, Geneva University Hospitals, 1205 Geneva, Switzerland; (R.V.H.); (M.T.C.-R.); (E.R.); (L.Q.); (C.G.); (E.H.); (M.G.); (M.A.)
| | - Caterina Stafuzza
- Ear-Nose-Throat/Head and Neck Surgery Division, Geneva University Hospitals, 1205 Geneva, Switzerland; (C.S.); (P.S.); (N.G.); (H.C.-V.)
| | - Lina Quteineh
- Division of Genetic Medicine, Geneva University Hospitals, 1205 Geneva, Switzerland; (R.V.H.); (M.T.C.-R.); (E.R.); (L.Q.); (C.G.); (E.H.); (M.G.); (M.A.)
| | - Corinne Gehrig
- Division of Genetic Medicine, Geneva University Hospitals, 1205 Geneva, Switzerland; (R.V.H.); (M.T.C.-R.); (E.R.); (L.Q.); (C.G.); (E.H.); (M.G.); (M.A.)
| | - Eva Hammar
- Division of Genetic Medicine, Geneva University Hospitals, 1205 Geneva, Switzerland; (R.V.H.); (M.T.C.-R.); (E.R.); (L.Q.); (C.G.); (E.H.); (M.G.); (M.A.)
| | - Michel Guipponi
- Division of Genetic Medicine, Geneva University Hospitals, 1205 Geneva, Switzerland; (R.V.H.); (M.T.C.-R.); (E.R.); (L.Q.); (C.G.); (E.H.); (M.G.); (M.A.)
| | - Marc Abramowicz
- Division of Genetic Medicine, Geneva University Hospitals, 1205 Geneva, Switzerland; (R.V.H.); (M.T.C.-R.); (E.R.); (L.Q.); (C.G.); (E.H.); (M.G.); (M.A.)
| | - Pascal Senn
- Ear-Nose-Throat/Head and Neck Surgery Division, Geneva University Hospitals, 1205 Geneva, Switzerland; (C.S.); (P.S.); (N.G.); (H.C.-V.)
| | - Nils Guinand
- Ear-Nose-Throat/Head and Neck Surgery Division, Geneva University Hospitals, 1205 Geneva, Switzerland; (C.S.); (P.S.); (N.G.); (H.C.-V.)
| | - Helene Cao-Van
- Ear-Nose-Throat/Head and Neck Surgery Division, Geneva University Hospitals, 1205 Geneva, Switzerland; (C.S.); (P.S.); (N.G.); (H.C.-V.)
| | - Ariane Paoloni-Giacobino
- Division of Genetic Medicine, Geneva University Hospitals, 1205 Geneva, Switzerland; (R.V.H.); (M.T.C.-R.); (E.R.); (L.Q.); (C.G.); (E.H.); (M.G.); (M.A.)
- Correspondence:
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80
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Genetic etiology of hereditary hearing loss in the Gulf Cooperation Council countries. Hum Genet 2021; 141:595-605. [PMID: 34338889 DOI: 10.1007/s00439-021-02323-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2021] [Accepted: 07/19/2021] [Indexed: 10/20/2022]
Abstract
The past 30 years have seen an exponential growth concerning the identification of genes and variants responsible for hereditary hearing loss (HL) worldwide. This has led to a huge gain in our understanding of molecular mechanisms of hearing and deafness, which improved diagnosis for populations with hereditary HL. Many communities around the world, especially in the Middle East and North Africa, have a high prevalence of consanguineous marriages. Congenital monogenic conditions, such as recessive HL, are more common in these populations due to high consanguinity rates. Many studies have shown that high rates of consanguinity, endogamy, and first cousin marriages were observed in the six countries of the Gulf Cooperation Council (GCC). The intent of this study is to investigate the etiology of HL in the GCC region. A deep literature review of genes and variants responsible for HL in this region revealed 89 recessive DNA pathogenic variants reported in 138 cases/familial cases. A total of 21 genes responsible for non-syndromic hearing loss (NSHL) and 17 genes associated with syndromic hearing loss (SHL) were reported in cases from the GCC region. Out of 156 reported affected cases, 112 showed HL only, and 44 showed HL associated with other clinical manifestations. This data suggests that in the GCC region 72% of HL forms are non-syndromic and 28% are syndromic. For individuals with NSHL, 66% of variants were detected in four genes (GJB2, OTOF, TMC1 and CDH23), with a predominance of variants located in the GJB2 gene (37.5%). However, among SHL, Usher syndrome was the more frequent as it has been observed in 41% of the reported syndromic GCC cases. Finally, our analysis showed that HL genetics testing and research in the GCC region took advantage of the next generation sequencing (NGS)-based techniques, as approximately 58% of reported variants were identified using this technology.
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Lin YH, Wu PC, Tsai CY, Lin YH, Lo MY, Hsu SJ, Lin PH, Erdenechuluun J, Wu HP, Hsu CJ, Wu CC, Chen PL. Hearing Impairment with Monoallelic GJB2 Variants: A GJB2 Cause or Non-GJB2 Cause? J Mol Diagn 2021; 23:1279-1291. [PMID: 34325055 DOI: 10.1016/j.jmoldx.2021.07.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Revised: 03/23/2021] [Accepted: 07/07/2021] [Indexed: 12/26/2022] Open
Abstract
Recessive variants in GJB2 are the most common genetic cause of sensorineural hearing impairment. However, in many patients, only one variant in the GJB2 coding region is identified using conventional sequencing strategy (eg, Sanger sequencing), resulting in nonconfirmative diagnosis. Conceivably, there might be other unidentified pathogenic variants in the noncoding region of GJB2 or other deafness-causing genes in these patients. To address this, a next-generation sequencing-based diagnostic panel targeting the entire GJB2 gene and the coding regions of 158 other known deafness-causing genes was designed and applied to 95 patients with nonsyndromic sensorineural hearing impairment (including 81 Han Taiwanese and 14 Mongolian patients) in whom only a single GJB2 variant had been detected using conventional Sanger sequencing. The panel confirmed the genetic diagnosis in 24 patients (25.3%). Twenty-two of them had causative variants in several deafness-causing genes other than GJB2, including MYO15A, MYO7A, TECTA, POU4F3, KCNQ4, SLC26A4, OTOF, MT-RNR1, MITF, WFS1, and USH2A. The other two patients had causative variants in GJB2, including a Taiwanese patient with a mosaic maternal uniparental disomy c.235delC variant (approximately 69% mosaicism) and a Mongolian patient with compound heterozygous c.35dupG and c.35delG variants, which occurred at the same site. This study demonstrates the utility of next-generation sequencing in clarifying the genetic diagnosis of hearing-impaired patients with nonconfirmative GJB2 genotypes on conventional genetic examinations.
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Affiliation(s)
- Yi-Hsin Lin
- Department of Otolaryngology, National Taiwan University Hospital, National Taiwan University Hospital, Taipei, Taiwan; Institute of Molecular Medicine, National Taiwan University College of Medicine, Taipei, Taiwan
| | - Ping-Che Wu
- College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Cheng-Yu Tsai
- Department of Otolaryngology, National Taiwan University Hospital, National Taiwan University Hospital, Taipei, Taiwan; Graduate Institutes of Medical Genomic, National Taiwan University College of Medicine, Taipei, Taiwan
| | - Yin-Hung Lin
- Department of Otolaryngology, National Taiwan University Hospital, National Taiwan University Hospital, Taipei, Taiwan; Graduate Institutes of Medical Genomic, National Taiwan University College of Medicine, Taipei, Taiwan
| | - Ming-Yu Lo
- Department of Otolaryngology, National Taiwan University Hospital, National Taiwan University Hospital, Taipei, Taiwan; Institute of Molecular Medicine, National Taiwan University College of Medicine, Taipei, Taiwan
| | - Shu-Jui Hsu
- Graduate Institutes of Medical Genomic, National Taiwan University College of Medicine, Taipei, Taiwan
| | - Pei-Hsuan Lin
- Department of Otolaryngology, National Taiwan University Hospital Yunlin Branch, Yunlin, Taiwan
| | - Jargalkhuu Erdenechuluun
- Department of Otolaryngology, Mongolian National University of Medical Sciences, Ulaanbaatar, Mongolia; The EMJJ Otolaryngology Hospital, Ulaanbaatar, Mongolia
| | - Hung-Pin Wu
- Department of Otolaryngology Head and Neck Surgery, Taichung Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, Taichung, Taiwan; School of Medicine, Tzu Chi University, Hualien, Taiwan
| | - Chuan-Jen Hsu
- Department of Otolaryngology, National Taiwan University Hospital, National Taiwan University Hospital, Taipei, Taiwan; Department of Otolaryngology Head and Neck Surgery, Taichung Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, Taichung, Taiwan
| | - Chen-Chi Wu
- Department of Otolaryngology, National Taiwan University Hospital, National Taiwan University Hospital, Taipei, Taiwan; Clinical Medicine, National Taiwan University College of Medicine, Taipei, Taiwan.
| | - Pei-Lung Chen
- Institute of Molecular Medicine, National Taiwan University College of Medicine, Taipei, Taiwan; Graduate Institutes of Medical Genomic, National Taiwan University College of Medicine, Taipei, Taiwan; Clinical Medicine, National Taiwan University College of Medicine, Taipei, Taiwan; Department of Medical Genetics, National Taiwan University Hospital, National Taiwan University Hospital, Taipei, Taiwan; Department of Internal Medicine, National Taiwan University Hospital, National Taiwan University Hospital, Taipei, Taiwan.
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82
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Hearing Screening Combined with Target Gene Panel Testing Increased Etiological Diagnostic Yield in Deaf Children. Neural Plast 2021; 2021:6151973. [PMID: 34335733 PMCID: PMC8324351 DOI: 10.1155/2021/6151973] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Revised: 06/09/2021] [Accepted: 07/11/2021] [Indexed: 12/16/2022] Open
Abstract
Genetic testing is the gold standard for exploring the etiology of congenital hearing loss. Here, we enrolled 137 Chinese patients with congenital hearing loss to describe the molecular epidemiology by using 127 gene panel testing or 159 variant testing. Sixty-three deaf children received 127 gene panel testing, while seventy-four patients received 159 variant testing. By use of 127 gene panel testing, more mutant genes and variants were identified. The most frequent mutant genes were GJB2, SLC26A4, MYO15A, CDH23, and OTOF. By analyzing the patients who received 127 gene panel testing, we found that 51 deaf children carried variants which were not included in 159 variant testing. Therefore, a large number of patients would be misdiagnosed if only 159 variant testing is used. This study highlights the advantage of 127 gene panel testing, and it suggests that broader genetic testing should be done to identify the genetic etiology of congenital hearing loss.
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83
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Kohrman D, Borges BC, Cassinotti L, Ji L, Corfas G. Axon-glia interactions in the ascending auditory system. Dev Neurobiol 2021; 81:546-567. [PMID: 33561889 PMCID: PMC9004231 DOI: 10.1002/dneu.22813] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Revised: 11/25/2020] [Accepted: 02/05/2021] [Indexed: 11/09/2022]
Abstract
The auditory system detects and encodes sound information with high precision to provide a high-fidelity representation of the environment and communication. In mammals, detection occurs in the peripheral sensory organ (the cochlea) containing specialized mechanosensory cells (hair cells) that initiate the conversion of sound-generated vibrations into action potentials in the auditory nerve. Neural activity in the auditory nerve encodes information regarding the intensity and frequency of sound stimuli, which is transmitted to the auditory cortex through the ascending neural pathways. Glial cells are critical for precise control of neural conduction and synaptic transmission throughout the pathway, allowing for the precise detection of the timing, frequency, and intensity of sound signals, including the sub-millisecond temporal fidelity is necessary for tasks such as sound localization, and in humans, for processing complex sounds including speech and music. In this review, we focus on glia and glia-like cells that interact with hair cells and neurons in the ascending auditory pathway and contribute to the development, maintenance, and modulation of neural circuits and transmission in the auditory system. We also discuss the molecular mechanisms of these interactions, their impact on hearing and on auditory dysfunction associated with pathologies of each cell type.
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Affiliation(s)
- David Kohrman
- Kresge Hearing Research Institute and Department of Otolaryngology - Head and Neck Surgery, University of Michigan, 1150 West. Medical Center Dr., Ann Arbor, MI 48109, USA
| | - Beatriz C. Borges
- Kresge Hearing Research Institute and Department of Otolaryngology - Head and Neck Surgery, University of Michigan, 1150 West. Medical Center Dr., Ann Arbor, MI 48109, USA
| | - Luis Cassinotti
- Kresge Hearing Research Institute and Department of Otolaryngology - Head and Neck Surgery, University of Michigan, 1150 West. Medical Center Dr., Ann Arbor, MI 48109, USA
| | - Lingchao Ji
- Kresge Hearing Research Institute and Department of Otolaryngology - Head and Neck Surgery, University of Michigan, 1150 West. Medical Center Dr., Ann Arbor, MI 48109, USA
| | - Gabriel Corfas
- Kresge Hearing Research Institute and Department of Otolaryngology - Head and Neck Surgery, University of Michigan, 1150 West. Medical Center Dr., Ann Arbor, MI 48109, USA
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84
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Zhang Q, Qin T, Hu W, Janjua MU, Jin P. Putative Digenic GJB2/MYO7A Inheritance of Hearing Loss Detected in a Patient with 48,XXYY Klinefelter Syndrome. Hum Hered 2021; 85:117-124. [PMID: 34192699 DOI: 10.1159/000516854] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2021] [Accepted: 04/01/2021] [Indexed: 11/19/2022] Open
Abstract
OBJECTIVES Nonsyndromic hearing loss (NSHL) is the most frequent type of hereditary hearing impairment. Here, we explored the underlying genetic cause of NSHL in a three-generation family using whole-exome sequencing. The proband had concomitant NSHL and rare 48,XXYY Klinefelter syndrome. MATERIAL AND METHODS Genomic DNA was extracted from the peripheral blood of the proband and their family members. Sanger sequencing and pedigree verification were performed on the pathogenic variants filtered by whole-exome sequencing. The function of the variants was analyzed using bioinformatics software. RESULTS The proband was digenic heterozygous for p.V37I in the GJB2 gene and p.L347I in the MYO7A gene. The proband's mother had normal hearing and did not have any variant. The proband's father and uncle both had NSHL and were compound for the GJB2 p.V37I and MYO7A p.L347I variants, thus indicating a possible GJB2/MYO7A digenic inheritance of NSHL. 48,XXYY Klinefelter syndrome was discovered in the proband after the karyotype analysis, while his parents both had normal karyotypes. CONCLUSIONS Our findings reported a putative GJB2/MYO7A digenic inheritance form of hearing loss, expanding the genotype and phenotype spectrum of NSHL. In addition, this is the first report of concomitant NSHL and 48,XXYY syndrome.
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Affiliation(s)
- Qin Zhang
- Department of Endocrinology, The Third Xiangya Hospital, Central South University, Changsha, China
| | - Tiantian Qin
- Department of Endocrinology, The Third Xiangya Hospital, Central South University, Changsha, China
| | - Wenmu Hu
- Department of Endocrinology, The Third Xiangya Hospital, Central South University, Changsha, China
| | - Muhammad Usman Janjua
- Department of Endocrinology, The Third Xiangya Hospital, Central South University, Changsha, China
| | - Ping Jin
- Department of Endocrinology, The Third Xiangya Hospital, Central South University, Changsha, China
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85
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Abstract
Congenital hearing loss is the most common birth defect, estimated to affect 2-3 in every 1000 births. Currently there is no cure for hearing loss. Treatment options are limited to hearing aids for mild and moderate cases, and cochlear implants for severe and profound hearing loss. Here we provide a literature overview of the environmental and genetic causes of congenital hearing loss, common animal models and methods used for hearing research, as well as recent advances towards developing therapies to treat congenital deafness. © 2021 The Authors.
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Affiliation(s)
- Justine M Renauld
- Department of Otolaryngology, Head & Neck Surgery, Case Western Reserve University School of Medicine, Cleveland, Ohio
| | - Martin L Basch
- Department of Otolaryngology, Head & Neck Surgery, Case Western Reserve University School of Medicine, Cleveland, Ohio.,Department of Genetics and Genome Sciences, Case Western Reserve School of Medicine, Cleveland, Ohio.,Department of Biology, Case Western Reserve University, Cleveland, Ohio.,Department of Otolaryngology, Head & Neck Surgery, University Hospitals, Cleveland, Ohio
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86
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Torkamandi S, Bayat S, Mirfakhraie R, Rezaei S, Askari M, Piltan S, Gholami M. Targeted sequencing of CDH23 and GJB2 genes in an Iranian pedigree with Usher syndrome and non-syndromic hearing loss. GENE REPORTS 2021. [DOI: 10.1016/j.genrep.2021.101149] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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87
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Petrova NV, Marakhonov AV, Balinova NV, Abrukova AV, Konovalov FA, Kutsev SI, Zinchenko RA. Genetic Variant c.245A>G (p.Asn82Ser) in GIPC3 Gene Is a Frequent Cause of Hereditary Nonsyndromic Sensorineural Hearing Loss in Chuvash Population. Genes (Basel) 2021; 12:820. [PMID: 34071867 PMCID: PMC8226456 DOI: 10.3390/genes12060820] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2021] [Revised: 05/23/2021] [Accepted: 05/25/2021] [Indexed: 11/05/2022] Open
Abstract
Hereditary nonsyndromic sensorineural hearing loss is a disease in which hearing loss occurs due to damage to the organ of the inner ear, the auditory nerve, or the center in the brain that is responsible for the perception of sound, characterized by wide locus and allelic heterogeneity and different types of inheritance. Given the diversity of population of the Russian Federation, it seems necessary to study the ethnic characteristics of the molecular causes of the disease. The aim is to study the molecular and genetic causes of hereditary sensorineural hearing loss in Chuvash, the fifth largest ethnic group in Russia. DNA samples of 26 patients from 21 unrelated Chuvash families from the Republic of Chuvashia, in whom the diagnosis of hereditary sensorineural hearing loss had been established, were analyzed using a combination of targeted Sanger sequencing, multiplex ligase-dependent probe amplification, and whole exome sequencing. The homozygous variant NM_133261.3(GIPC3):c.245A>G (p.Asn82Ser) is the major molecular cause of hereditary sensorineural hearing loss in 23% of Chuvash patients (OMIM #601869). Its frequency was 25% in patients and 1.1% in healthy Chuvash population. Genotyping of the NM_133261.3(GIPC3):c.245A>G (p.Asn82Ser) variant in five neighboring populations from the Volga-Ural region (Russian, Udmurt, Mary, Tatar, Bushkir) found no evidence that this variant is common in those populations.
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Affiliation(s)
- Nika V. Petrova
- Research Centre for Medical Genetics, 115522 Moscow, Russia; (N.V.P.); (N.V.B.); (S.I.K.); (R.A.Z.)
| | - Andrey V. Marakhonov
- Research Centre for Medical Genetics, 115522 Moscow, Russia; (N.V.P.); (N.V.B.); (S.I.K.); (R.A.Z.)
| | - Natalia V. Balinova
- Research Centre for Medical Genetics, 115522 Moscow, Russia; (N.V.P.); (N.V.B.); (S.I.K.); (R.A.Z.)
| | - Anna V. Abrukova
- Presidential Perinatal Center of the Public Health Ministry of Chuvashia, Genetic Counseling Department, 428018 Cheboksary, Russia;
| | | | - Sergey I. Kutsev
- Research Centre for Medical Genetics, 115522 Moscow, Russia; (N.V.P.); (N.V.B.); (S.I.K.); (R.A.Z.)
| | - Rena A. Zinchenko
- Research Centre for Medical Genetics, 115522 Moscow, Russia; (N.V.P.); (N.V.B.); (S.I.K.); (R.A.Z.)
- N.A. Semashko National Research Institute of Public Health, 105064 Moscow, Russia
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88
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Fukunaga I, Oe Y, Danzaki K, Ohta S, Chen C, Shirai K, Kawano A, Ikeda K, Kamiya K. Modeling gap junction beta 2 gene-related deafness with human iPSC. Hum Mol Genet 2021; 30:1429-1442. [PMID: 33997905 DOI: 10.1093/hmg/ddab097] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Revised: 03/29/2021] [Accepted: 03/31/2021] [Indexed: 02/06/2023] Open
Abstract
There are >120 forms of non-syndromic deafness associated with identified genetic loci. In particular, mutation of the gap junction beta 2 gene (GJB2), which encodes connexin (CX)26 protein, is the most frequent cause of hereditary deafness worldwide. We previously described an induction method to develop functional CX26 gap junction-forming cells from mouse-induced pluripotent stem cells (iPSCs) and generated in vitro models for GJB2-related deafness. However, functional CX26 gap junction-forming cells derived from human iPSCs or embryonic stem cells (ESCs) have not yet been reported. In this study, we generated human iPSC-derived functional CX26 gap junction-forming cells (iCX26GJCs), which have the characteristics of cochlear supporting cells. These iCX26GJCs had gap junction plaque-like formations at cell-cell borders and co-expressed several markers that are expressed in cochlear supporting cells. Furthermore, we generated iCX26GJCs derived from iPSCs from two patients with the most common GJB2 mutation in Asia, and these cells reproduced the pathology of GJB2-related deafness. These in vitro models may be useful for establishing optimal therapies and drug screening for various mutations in GJB2-related deafness.
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Affiliation(s)
- Ichiro Fukunaga
- Department of Otorhinolaryngology, Juntendo University Faculty of Medicine, Tokyo 1138421, Japan
| | - Yoko Oe
- Department of Otorhinolaryngology, Juntendo University Faculty of Medicine, Tokyo 1138421, Japan
| | - Keiko Danzaki
- Department of Otorhinolaryngology, Juntendo University Faculty of Medicine, Tokyo 1138421, Japan
| | - Sayaka Ohta
- Department of Otorhinolaryngology, Juntendo University Faculty of Medicine, Tokyo 1138421, Japan
| | - Cheng Chen
- Department of Otorhinolaryngology, Juntendo University Faculty of Medicine, Tokyo 1138421, Japan
| | - Kyoko Shirai
- Department of Otolaryngology, Head and Neck Surgery, Tokyo Medical University, Tokyo 1600023, Japan
| | - Atsushi Kawano
- Department of Otolaryngology, Head and Neck Surgery, Tokyo Medical University, Tokyo 1600023, Japan
| | - Katsuhisa Ikeda
- Department of Otorhinolaryngology, Juntendo University Faculty of Medicine, Tokyo 1138421, Japan
| | - Kazusaku Kamiya
- Department of Otorhinolaryngology, Juntendo University Faculty of Medicine, Tokyo 1138421, Japan
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89
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Safka Brozkova D, Uhrova Meszarosova A, Lassuthova P, Varga L, Staněk D, Borecká S, Laštůvková J, Čejnová V, Rašková D, Lhota F, Gašperíková D, Seeman P. The Cause of Hereditary Hearing Loss in GJB2 Heterozygotes-A Comprehensive Study of the GJB2/DFNB1 Region. Genes (Basel) 2021; 12:genes12050684. [PMID: 34062854 PMCID: PMC8147375 DOI: 10.3390/genes12050684] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Revised: 04/27/2021] [Accepted: 04/28/2021] [Indexed: 12/14/2022] Open
Abstract
Hearing loss is a genetically heterogeneous sensory defect, and the frequent causes are biallelic pathogenic variants in the GJB2 gene. However, patients carrying only one heterozygous pathogenic (monoallelic) GJB2 variant represent a long-lasting diagnostic problem. Interestingly, previous results showed that individuals with a heterozygous pathogenic GJB2 variant are two times more prevalent among those with hearing loss compared to normal-hearing individuals. This excess among patients led us to hypothesize that there could be another pathogenic variant in the GJB2 region/DFNB1 locus. A hitherto undiscovered variant could, in part, explain the cause of hearing loss in patients and would mean reclassifying them as patients with GJB2 biallelic pathogenic variants. In order to detect an unknown causal variant, we examined 28 patients using NGS with probes that continuously cover the 0.4 Mb in the DFNB1 region. An additional 49 patients were examined by WES to uncover only carriers. We did not reveal a second pathogenic variant in the DFNB1 region. However, in 19% of the WES-examined patients, the cause of hearing loss was found to be in genes other than the GJB2. We present evidence to show that a substantial number of patients are carriers of the GJB2 pathogenic variant, albeit only by chance.
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Affiliation(s)
- Dana Safka Brozkova
- Neurogenetic laboratory, Department of Paediatric Neurology, 2nd Faculty of Medicine, Charles University and University Hospital Motol, 15006 Prague, Czech Republic; (A.U.M.); (P.L.); (D.S.); (P.S.)
- Correspondence:
| | - Anna Uhrova Meszarosova
- Neurogenetic laboratory, Department of Paediatric Neurology, 2nd Faculty of Medicine, Charles University and University Hospital Motol, 15006 Prague, Czech Republic; (A.U.M.); (P.L.); (D.S.); (P.S.)
| | - Petra Lassuthova
- Neurogenetic laboratory, Department of Paediatric Neurology, 2nd Faculty of Medicine, Charles University and University Hospital Motol, 15006 Prague, Czech Republic; (A.U.M.); (P.L.); (D.S.); (P.S.)
| | - Lukáš Varga
- Department of Otorhinolaryngology–Head and Neck Surgery, Faculty of Medicine and University Hospital, Comenius University, 85107 Bratislava, Slovakia;
- Diabgene Laboratory, Institute of Experimental Endocrinology, Biomedical Research Center, Slovak Academy of Sciences, 84505 Bratislava, Slovakia; (S.B.); (D.G.)
| | - David Staněk
- Neurogenetic laboratory, Department of Paediatric Neurology, 2nd Faculty of Medicine, Charles University and University Hospital Motol, 15006 Prague, Czech Republic; (A.U.M.); (P.L.); (D.S.); (P.S.)
| | - Silvia Borecká
- Diabgene Laboratory, Institute of Experimental Endocrinology, Biomedical Research Center, Slovak Academy of Sciences, 84505 Bratislava, Slovakia; (S.B.); (D.G.)
| | - Jana Laštůvková
- Department of Medical Genetics, Masaryk Hospital in Usti nad Labem, Regional Health Corporation, 40011 Ústí nad Labem, Czech Republic; (J.L.); (V.Č.)
| | - Vlasta Čejnová
- Department of Medical Genetics, Masaryk Hospital in Usti nad Labem, Regional Health Corporation, 40011 Ústí nad Labem, Czech Republic; (J.L.); (V.Č.)
| | - Dagmar Rašková
- Centre for Medical Genetics and Reproductive Medicine GENNET, 17000 Prague, Czech Republic; (D.R.); (F.L.)
| | - Filip Lhota
- Centre for Medical Genetics and Reproductive Medicine GENNET, 17000 Prague, Czech Republic; (D.R.); (F.L.)
| | - Daniela Gašperíková
- Diabgene Laboratory, Institute of Experimental Endocrinology, Biomedical Research Center, Slovak Academy of Sciences, 84505 Bratislava, Slovakia; (S.B.); (D.G.)
| | - Pavel Seeman
- Neurogenetic laboratory, Department of Paediatric Neurology, 2nd Faculty of Medicine, Charles University and University Hospital Motol, 15006 Prague, Czech Republic; (A.U.M.); (P.L.); (D.S.); (P.S.)
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90
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Mahfood M, Chouchen J, Kamal Eddine Ahmad Mohamed W, Al Mutery A, Harati R, Tlili A. Whole exome sequencing, in silico and functional studies confirm the association of the GJB2 mutation p.Cys169Tyr with deafness and suggest a role for the TMEM59 gene in the hearing process. Saudi J Biol Sci 2021; 28:4421-4429. [PMID: 34354426 PMCID: PMC8324942 DOI: 10.1016/j.sjbs.2021.04.036] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2020] [Revised: 04/11/2021] [Accepted: 04/12/2021] [Indexed: 12/25/2022] Open
Abstract
The development of next generation sequencing techniques has facilitated the detection of mutations at an unprecedented rate. These efficient tools have been particularly beneficial for extremely heterogeneous disorders such as autosomal recessive non-syndromic hearing loss, the most common form of genetic deafness. GJB2 mutations are the most common cause of hereditary hearing loss. Amongst them the NM_004004.5: c.506G > A (p.Cys169Tyr) mutation has been associated with varying severity of hearing loss with unclear segregation patterns. In this study, we report a large consanguineous Emirati family with severe to profound hearing loss fully segregating the GJB2 missense mutation p.Cys169Tyr. Whole exome sequencing (WES), in silico, splicing and expression analyses ruled out the implication of any other variants and confirmed the implication of the p.Cys169Tyr mutation in this deafness family. We also show preliminary murine expression analysis that suggests a link between the TMEM59 gene and the hearing process. The present study improves our understanding of the molecular pathogenesis of hearing loss. It also emphasizes the significance of combining next generation sequencing approaches and segregation analyses especially in the diagnosis of disorders characterized by complex genetic heterogeneity.
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Key Words
- ARNSHL, autosomal recessive non-syndromic hearing loss
- Actb, Actin beta
- BAM, Binary Alignment Map
- BWA, Burrows-Wheeler Aligner
- C1QTNF9, C1q and TNF related 9
- Cx26, Connexin 26
- ESRRAP2, Estrogen-Related Receptor Alpha Pseudogene 2
- GJB2 gene
- GJB2, Gap Junction Protein Beta 2
- HHLA1, HERV-H LTR-Associating 1
- HL, Hearing loss
- KCNQ3, Potassium Voltage-Gated Channel Subfamily Q Member 3
- Missense mutation
- NGS, next generation sequencing
- NSHL, Non-syndromic hearing loss
- Non-syndromic hearing loss
- PROVEAN, Protein Variation Effect Analyzer
- PolyPhen-2, Polymorphism Phenotyping v2
- RFLP, restriction fragment length polymorphism
- ROH, runs of homozygosity
- RT-PCR, reverse transcription PCR
- RT-qPCR, quantitative reverse transcription PCR
- SAM, Sequence Alignment/Map
- SIFT, Sorting Intolerant From Tolerant
- SJL, Swiss Jim Lambert
- SPATA13, Spermatogenesis Associated 13
- ST3GAL1, ST3 Beta-Galactoside Alpha-2,3-Sialyltransferase 1
- TMEM59, Transmembrane Protein 59
- UAE, United Arab Emirates
- VariMAT, Variation and Mutation Annotation Toolkit
- WES, Whole exome sequencing
- Whole exome sequencing
- dpSNP, Single Nucleotide Polymorphism Database
- gEAR, gene Expression Analysis Resource
- gnomAD, genome aggregation database
- qPCR, quantitative PCR
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Affiliation(s)
- Mona Mahfood
- Department of Applied Biology, College of Sciences, University of Sharjah, Sharjah, United Arab Emirates
| | - Jihen Chouchen
- Human Genetics and Stem Cell Research Group, Research Institute of Sciences and Engineering, University of Sharjah, Sharjah, United Arab Emirates
| | - Walaa Kamal Eddine Ahmad Mohamed
- Human Genetics and Stem Cell Research Group, Research Institute of Sciences and Engineering, University of Sharjah, Sharjah, United Arab Emirates
| | - Abdullah Al Mutery
- Department of Applied Biology, College of Sciences, University of Sharjah, Sharjah, United Arab Emirates.,Human Genetics and Stem Cell Research Group, Research Institute of Sciences and Engineering, University of Sharjah, Sharjah, United Arab Emirates
| | - Rania Harati
- Department of Pharmacy Practice and Pharmacotherapeutics, College of Pharmacy, University of Sharjah, Sharjah, United Arab Emirates
| | - Abdelaziz Tlili
- Department of Applied Biology, College of Sciences, University of Sharjah, Sharjah, United Arab Emirates.,Human Genetics and Stem Cell Research Group, Research Institute of Sciences and Engineering, University of Sharjah, Sharjah, United Arab Emirates
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91
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Abstract
BACKGROUND Hearing loss (HL) is a heterogeneous condition that causes partial or complete hearing impairment. Hundreds of variants in more than 60 genes have been reported to be associated with Hereditary HL (HHL). The HHL prevalence is thought to be high in the Arab population; however, the genetic epidemiology of HHL among Arab populations is understudied. This study aimed to systematically analyze the genetic epidemiology of HHL in Arab countries. METHODS We searched four literature databases (PubMed, Scopus, Science Direct, and Web of Science) from the time of inception until January 2019 using broad search terms to capture all the reported epidemiological and genetic data related to Arab patients with HHL. FINDINGS A total of 2,600 citations were obtained; 96 studies met our inclusion criteria. Our search strategy yielded 121,276 individuals who were tested for HL over 52 years (1966-2018), of whom 8,099 were clinically diagnosed with HL and belonged to 16 Arab countries. A total of 5,394 patients and 61 families with HHL were genotyped, of whom 336 patients and 6 families carried 104 variants in 44 genes and were from 17/22 Arab countries. Of these variants, 72 (in 41 genes) were distinctive to Arab patients. Arab patients manifested distinctive clinical phenotypes. The incidence of HHL in the captured studies ranged from 1.20 to 18 per 1,000 births per year, and the prevalence was the highest in Iraq (76.3%) and the lowest in Jordan (1.5%). INTERPRETATION This is the first systematic review to capture the prevalence and spectrum of variants associated with HHL in an Arab population. There appears to be a distinctive clinical picture for Arab patients with HHL, and the range and distribution of variants among Arab patients differ from those noted in other affected ethnic groups.
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92
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Squecco R, Pierucci F, Idrizaj E, Frati A, Lenci E, Vicenti C, Iachini MC, Martinesi M, Garella R, Baccari MC, Francini F, Meacci E. Ceramide/protein phosphatase 2A axis is engaged in gap junction impairment elicited by PCB153 in liver stem-like progenitor cells. Mol Cell Biochem 2021; 476:3111-3126. [PMID: 33837873 PMCID: PMC8263450 DOI: 10.1007/s11010-021-04135-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Accepted: 03/11/2021] [Indexed: 12/22/2022]
Abstract
The widespread environmental pollutant 2,2',4,4',5,5'-hexachlorobiphenyl (PCB153) is a non-dioxin-like toxicant. It is a potential carcinogen compound able to induce gap junction (GJ) intercellular communication impairment, probably the first non-genomic event leading to tumor promotion. Although PCBs have been known for many years, the molecular mode of PCB153 action is still unclear. Recent studies from our research group have shown that the toxicant elicits a transient modulation of connexin (Cx) 43-formed GJs in hepatic stem-like WB-F344 cells involving sphingosine 1-phosphate (S1P) path. Taking into account that other strictly related bioactive sphingolipids, such as ceramide (Cer), may have different effects from S1P, here we aim to clarify the signaling paths engaged by PCB153 in the control of GJs, focusing primarily on the role of Cer. Accordingly, we have achieved a combined biomolecular and electrophysiological analysis of GJs in cultured WB-F344 cells treated with PCB153 at different time points. We have found that the toxicant elicited a time-dependent regulation of GJs formed by different Cx isoforms, through a transient modulation of Cer/Cer kinase (CerK) axis and, in turn, of protein phosphatase 2A (PP2A). Our new findings demonstrate the existence of a specific molecular mechanism downstream to Cer, which distinctly affects the voltage-dependent and -independent GJs in liver stem-like cells, and open new opportunities for the identification of additional potential targets of these environmental toxicants.
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Affiliation(s)
- Roberta Squecco
- Department of Experimental and Clinical Medicine, Section of Physiological Sciences, University of Florence, Viale GB Morgagni 63, 50134, Florence, Italy
| | - Federica Pierucci
- Department of Experimental and Clinical Biomedical Sciences "Mario Serio", Research unit of Molecular and Applied Biology, University of Florence, Viale GB Morgagni 50, 50134, Florence, Italy
| | - Eglantina Idrizaj
- Department of Experimental and Clinical Medicine, Section of Physiological Sciences, University of Florence, Viale GB Morgagni 63, 50134, Florence, Italy
| | - Alessia Frati
- Department of Experimental and Clinical Biomedical Sciences "Mario Serio", Research unit of Molecular and Applied Biology, University of Florence, Viale GB Morgagni 50, 50134, Florence, Italy
| | - Elena Lenci
- Department of Experimental and Clinical Biomedical Sciences "Mario Serio", Research unit of Molecular and Applied Biology, University of Florence, Viale GB Morgagni 50, 50134, Florence, Italy
| | - Catia Vicenti
- Department of Experimental and Clinical Biomedical Sciences "Mario Serio", Research unit of Molecular and Applied Biology, University of Florence, Viale GB Morgagni 50, 50134, Florence, Italy
| | - Maria Chiara Iachini
- Department of Experimental and Clinical Biomedical Sciences "Mario Serio", Research unit of Molecular and Applied Biology, University of Florence, Viale GB Morgagni 50, 50134, Florence, Italy
| | - Maria Martinesi
- Department of Experimental and Clinical Biomedical Sciences "Mario Serio", Research unit of Molecular and Applied Biology, University of Florence, Viale GB Morgagni 50, 50134, Florence, Italy
| | - Rachele Garella
- Department of Experimental and Clinical Medicine, Section of Physiological Sciences, University of Florence, Viale GB Morgagni 63, 50134, Florence, Italy
| | - Maria Caterina Baccari
- Department of Experimental and Clinical Medicine, Section of Physiological Sciences, University of Florence, Viale GB Morgagni 63, 50134, Florence, Italy
| | - Fabio Francini
- Department of Experimental and Clinical Medicine, Section of Physiological Sciences, University of Florence, Viale GB Morgagni 63, 50134, Florence, Italy
| | - Elisabetta Meacci
- Department of Experimental and Clinical Biomedical Sciences "Mario Serio", Research unit of Molecular and Applied Biology, University of Florence, Viale GB Morgagni 50, 50134, Florence, Italy.
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93
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Xiao C, Liu S, Wang H, Ding Y, Chen Y, Liu H. Genetic etiology study of four Chinese families with two nonsyndromic deaf children in succession by targeted next-generation sequencing. Mol Genet Genomic Med 2021; 9:e1634. [PMID: 33638616 PMCID: PMC8123758 DOI: 10.1002/mgg3.1634] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Revised: 12/09/2020] [Accepted: 02/10/2021] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Genetic components contribute significantly to the cause of hearing loss. Nonsyndromic hearing loss has been shown to have high genetic heterogeneity. For families who had given birth to two nonsyndromic deaf children in succession, it seems that their deafness was highly related to genetics. OBJECTIVES This study aimed to disclose the genetic causes of the subjects from the four Chinese families with two nonsyndromic deaf children in succession who failed to find the genetic etiology of the hearing loss by common deafness genetic screening (GJB2, GJB3, SLC26A4, and MT-RNR1, including 20 hot variants in 4 genes). METHODS Targeted next-generation sequencing (NGS) of 127 known deafness genes was performed in probands of four families, followed by a series of comprehensive analyses of all family members combined with a literature review of related genes. RESULTS We identified pathogenic variants in three families including c.919-2A>G/c.1985G>A in SLC26A4; c.109G>A (p.V37I) in GJB2; and m.7505T>C in MT-TS1. Sanger sequencing confirmed that these variants segregated with the hearing impairment of each family. We also identified c.331C>T/c.625-5C>T/c.5717G>A in CDH23; c.138T>C in POU3F4 in two families, in which the pathogenicity in clinical was likely pathogenic or unknown. CONCLUSIONS Using the NGS detection technology, we found the genetic etiology of the HL in part of deaf families. Our study provided a useful piece of information for the variant spectrum of hearing loss in Chinese families with two deaf children in succession.
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Affiliation(s)
- Caixia Xiao
- Tianjin Women and Children Healthcare CenterTianjinChina
| | - Shuang Liu
- Tianjin Women and Children Healthcare CenterTianjinChina
| | - Hongyue Wang
- Tianjin Women and Children Healthcare CenterTianjinChina
| | - Yibing Ding
- Tianjin Women and Children Healthcare CenterTianjinChina
| | - Yaqiu Chen
- Tianjin Women and Children Healthcare CenterTianjinChina
| | - Haiyan Liu
- Tianjin Women and Children Healthcare CenterTianjinChina
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Mostafa BE, El Sawi MA, Sabry SM, Hassan DM, Rezk Shafik M. Genetic Screening for 35delG Mutation in Egyptian Patients with Profound Sensorineural Hearing Loss Scheduled for Cochlear Implantation: A Population-Based Study. ORL J Otorhinolaryngol Relat Spec 2021; 83:181-186. [PMID: 33756453 DOI: 10.1159/000513752] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Accepted: 12/14/2020] [Indexed: 11/19/2022]
Abstract
OBJECTIVES The aim of this work was to assess the type and site of the 35delG gene mutation in patients presenting with profound SNHL and scheduled for cochlear implantation. The secondary objectives were to determine their geographical distribution throughout Egypt, screening of the parents for the mutation, and to correlate the type of mutation with clinical severity and outcomes after surgery. METHODS The study was carried out on 100 consecutive patients scheduled for cochlear implantation. Patients with syndromic hearing loss or noncongenital hearing loss (trauma, infections, and ototoxicity) were excluded. All patients were subjected to detailed history taking including geographic tagging for their origins in Egypt, imaging (CT and MRI cochlear implantation protocols), full audiological evaluation (PTA, ABR, and TEOAE), and genetic screening for GJB2 mutation using Invitrogen PCR mix and ApaI restriction enzyme (North America, CA, 10572-014). The parents of mutation-positive patients were also subjected to audiological and genetic analysis. All patients were subjected to postimplantation evaluation of hearing after 6 and 12 months. RESULTS There were 64 males and 36 females from 98 families. Ages ranged between 1.9 and 7 years (mean 3.72 years). They originated from all over Egypt but the majority came from the Giza and Cairo areas. The 35delG mutations were found in exon 2 in 31% of the cases and all were heterozygous. In the parents, 18 mothers and 13 fathers were positive but only 8 had mild to moderate SNHL. Hearing evaluation by pure tone and speech discrimination scores at 6 and 12 months showed that the 35delG children had a statistically better result compared to the children without this mutation. CONCLUSION The prevalence of the 35delG mutation in nonsyndromic children in this sample was 31% which is different from previous studies in the Egyptian population but close to the values found in other populations in the Mediterranean basin.
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Affiliation(s)
- Badr Eldin Mostafa
- Department of Otorhinolaryngology Head and Neck Surgery, Faculty of Medicine, Ain-Shams University, Cairo, Egypt,
| | - Mohammed Abdel El Sawi
- Department of Pediatrics and Medical Genetics, Faculty of Medicine, Ain-Shams University, Cairo, Egypt
| | - Sabry Magdi Sabry
- Department of Otorhinolaryngology Head and Neck Surgery, Faculty of Medicine, Ain-Shams University, Cairo, Egypt
| | - Dalia Mohammed Hassan
- Department of Otorhinolaryngology Head and Neck Surgery, Faculty of Medicine, Ain-Shams University, Cairo, Egypt
| | - Michael Rezk Shafik
- Department of Otorhinolaryngology Head and Neck Surgery, Faculty of Medicine, Ain-Shams University, Cairo, Egypt
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95
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Faistauer M, Lang Silva A, Félix TM, Todeschini de Souza L, Bohn R, Selaimen da Costa S, Petersen Schmidt Rosito L. Etiology of early hearing loss in Brazilian children. Braz J Otorhinolaryngol 2021; 88 Suppl 1:S33-S41. [PMID: 33839059 PMCID: PMC9734262 DOI: 10.1016/j.bjorl.2021.02.012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2020] [Revised: 01/22/2021] [Accepted: 02/28/2021] [Indexed: 12/16/2022] Open
Abstract
INTRODUCTION Hearing loss etiology depends on the population studied as well as on the ethnicity and the socio-economic condition of the analyzed region. Etiological diagnosis contributes to the improvement of preventive measures and to the early identification of this deficiency. OBJECTIVE To identify the etiological factors of hearing loss and its prevalence in a tertiary hospital in southern Brazil, to verify the frequency of mutations in GJB2 and GJB6 genes, and to correlate the degree of hearing loss with the etiological factors of deafness. METHODS This prevalence study involved 140 children with bilateral sensorineural or mixed hearing loss. Medical history, physical examination, audiometry, and evoked auditory brainstem response were conducted. Imaging and genetic examinations were also performed. RESULTS Etiologies and their prevalence were as follows: (a) indeterminate causes, 31.4%; (b) conditions related to neonatal period, 22.1%; (c) genetic, 22.1%; (d) auditory neuropathy, 10%; (e) other factors (cortical malformation, intracranial hemorrhage, and internal ear malformations), 7.9% and (f) congenital infections, 6.4%. Within the genetic cases, ten homozygous and seven heterozygotes of the 35delG mutation were identified, besides two cases of rare variants of GJB2: p.Try172* and p.Arg184Pro. One case with homozygosis of del(GJB6-D13S1830) was found. Regarding severity of hearing loss, in 78.6% of the cases the degree of hearing loss was profound and there were no significant differences when comparing between etiologies. CONCLUSION The number of indeterminate etiologies is still high and congenital CMV infection may be a possible cause of undiagnosed etiology for hearing loss. The predominance of etiologies related to neonatal conditions and infectious causes are characteristic of developing countries. The most prevalent mutation was 35delG, the main GJB2 gene, probably because of the European influence in the genotype of our population.
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Affiliation(s)
- Marina Faistauer
- Universidade Federal do Rio Grande do Sul, Faculdade de Medicina, Porto Alegre, RS, Brazil
| | - Alice Lang Silva
- Hospital de Clínicas de Porto Alegre, Departamento de Otorrinolaringologia e Cirurgia de Cabeça e Pescoço, Porto Alegre, RS, Brazil; Universidade Federal do Rio Grande do Sul, Faculdade de Medicina, Departamento de Oftalmologia e Otorrinolaringologia, Porto Alegre, RS, Brazil.
| | - Têmis Maria Félix
- Hospital de Clínicas de Porto Alegre, Departamento de Genética, Porto Alegre, RS, Brazil
| | | | - Renata Bohn
- Universidade Federal do Rio Grande do Sul, Faculdade de Medicina, Porto Alegre, RS, Brazil
| | - Sady Selaimen da Costa
- Hospital de Clínicas de Porto Alegre, Departamento de Otorrinolaringologia e Cirurgia de Cabeça e Pescoço, Porto Alegre, RS, Brazil; Universidade Federal do Rio Grande do Sul, Faculdade de Medicina, Departamento de Oftalmologia e Otorrinolaringologia, Porto Alegre, RS, Brazil
| | - Letícia Petersen Schmidt Rosito
- Hospital de Clínicas de Porto Alegre, Departamento de Otorrinolaringologia e Cirurgia de Cabeça e Pescoço, Porto Alegre, RS, Brazil; Universidade Federal do Rio Grande do Sul, Faculdade de Medicina, Departamento de Oftalmologia e Otorrinolaringologia, Porto Alegre, RS, Brazil
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96
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Li Y, Su J, Zhang J, Pei J, Li D, Zhang Y, Li J, Chen M, Zhu B. Targeted next-generation sequencing of deaf patients from Southwestern China. Mol Genet Genomic Med 2021; 9:e1660. [PMID: 33724713 PMCID: PMC8123756 DOI: 10.1002/mgg3.1660] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 02/23/2021] [Accepted: 02/24/2021] [Indexed: 11/06/2022] Open
Abstract
BACKGROUND Targeted next-generation sequencing is an efficient tool to identify pathogenic mutations of hereditary deafness. The molecular pathology of deaf patients in southwestern China is not fully understood. METHODS In this study, targeted next-generation sequencing of 127 deafness genes was performed on 84 deaf patients. They were not caused by common mutations of GJB2 gene, including c.35delG, c.109 G>A, c.167delT, c.176_191del16, c.235delC and c.299_300delAT. RESULTS In the cohorts of 84 deaf patients, we did not find any candidate pathogenic variants in 14 deaf patients (16.7%, 14/84). In other 70 deaf patients (83.3%, 70/84), candidate pathogenic variants were identified in 34 genes. Of these 70 deaf patients, the percentage of "Solved" and "Unsolved" patients was 51.43% (36/70) and 48.57% (34/70), respectively. The most common causative genes were SLC26A4 (12.9%, 9/70), MT-RNR1 (11.4%, 8/70), and MYO7A (2.9%, 2/70) in deaf patients. In "Unsolved" patients, possible pathogenic variants were most found in SLC26A4 (8.9%, 3/34), MYO7A (5.9%, 2/34), OTOF (5.9%, 2/34), and PDZD7 (5.9%, 2/34) genes. Interesting, several novel recessive pathogenic variants were identified, like SLC26A4 c.290T>G, SLC26A4 c.599A>G, PDZD7c.490 C>T, etc. CONCLUSION: In addition to common deafness genes, like GJB2, SLC26A4, and MT-RNR1 genes, other deafness genes (MYO7A, OTOF, PDZD7, etc.) were identified in deaf patients from southwestern China. Therefore, the spectrum of deafness genes in this area should be further studied.
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Affiliation(s)
- Yunlong Li
- Department of Medical Genetics, First People's Hospital of Yunnan Province, Kunming, Yunnan, China.,Affiliated Hospital of Kunming University of Science and Technology, Kunming, Yunnan, China
| | - Jie Su
- Department of Medical Genetics, First People's Hospital of Yunnan Province, Kunming, Yunnan, China
| | - Jingman Zhang
- Department of Medical Genetics, First People's Hospital of Yunnan Province, Kunming, Yunnan, China
| | - Jiahong Pei
- Department of Medical Genetics, First People's Hospital of Yunnan Province, Kunming, Yunnan, China
| | - Dongmei Li
- Department of Medical Genetics, First People's Hospital of Yunnan Province, Kunming, Yunnan, China
| | - Yinhong Zhang
- Department of Medical Genetics, First People's Hospital of Yunnan Province, Kunming, Yunnan, China
| | - Jingyu Li
- Department of Medical Genetics, First People's Hospital of Yunnan Province, Kunming, Yunnan, China.,Affiliated Hospital of Kunming University of Science and Technology, Kunming, Yunnan, China
| | - Menglang Chen
- Department of Medical Genetics, First People's Hospital of Yunnan Province, Kunming, Yunnan, China.,Affiliated Hospital of Kunming University of Science and Technology, Kunming, Yunnan, China
| | - Baosheng Zhu
- Department of Medical Genetics, First People's Hospital of Yunnan Province, Kunming, Yunnan, China.,Affiliated Hospital of Kunming University of Science and Technology, Kunming, Yunnan, China
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97
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Aliazami F, Farhud D, Zarif-Yeganeh M, Salehi S, Hosseinipour A, Sasanfar R, Eslami M. Gjb3 Gene Mutations in Non-Syndromic Hearing Loss of Bloch, Kurd, and Turkmen Ethnicities in Iran. IRANIAN JOURNAL OF PUBLIC HEALTH 2021; 49:2128-2135. [PMID: 33708733 PMCID: PMC7917519 DOI: 10.18502/ijph.v49i11.4730] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Background: Hearing loss (HL) is one of the most common heterogeneous congenital disabilities worldwide. Gap junction protein β-3 (GJB3) gene encodes Connexin31 protein (Cx31). The hereditary type of hearing impairment in this gene are known to cause both autosomal recessive and autosomal dominant form. In addition, GJB3 mutations have been involved in sensorineural deafness, erythrokeratodermia variabilis (EKV), and neuropathy diseases. We aimed to investigate GJB3 mutations in people suffering from HL among three different ethnicities of Iranian population (Baloch, Kurd, and Turkmen). Methods: In this descriptive study, 50 GJB2-negative non-syndromic hearing loss (NSHL) Iranian individuals from 3 ethnic groups of Baloch (n=17), Kurd (n =15) and Turkmen (n=18) were enrolled. DNA extractions, PCR, and mutation detection was carried out for the two large deletions of the GJB6, del (GJB6 -D13S1830,) and del (GJB6 -D13S1854) followed by direct DNA sequencing method for the GJB3. Results: DNA sequencing of GJB3 was shown a missense heterozygous mutation rs199689484 (NM_024009.3) GJB3: c.340G>A (p.Ala114Thr) in a Baloch patient, and a polymorphism rs35983826 (NM_024009.3) GJB3: c.798C>T (p.Asn266=) in a Turkman patient, in coding region of the GJB3. We did not detect del (GJB6 -D13S1830) and del (GJB6 -D13S1854) among these three ethnicities in Iran. Conclusion: Deafness is a heterogeneous disorder. Specific genes and mutations contribute to hearing loss that varies from locus to locus as well as from population to population.
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Affiliation(s)
- Farnoush Aliazami
- Department of Genetics, Tehran Medical Branch, Islamic Azad University, Tehran, Iran.,Applied Biotechnology Research Center, Tehran Medical Branch, Islamic Azad University, Tehran, Iran
| | - Dariush Farhud
- School of Public Health, Tehran University of Medical Sciences, Tehran, Iran.,Department of Basic Sciences, Iranian Academy of Medical Sciences, Tehran, Iran
| | - Marjan Zarif-Yeganeh
- Cellular and Molecular Endocrine Research Center, Research Institute for Endocrine Sciences, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Siamak Salehi
- Institute of Liver Studies, King's College Hospital, London, United Kingdom
| | - Azam Hosseinipour
- Department of Exceptional Children, Ministry of Education and Training of the Islamic Republic of Iran, Tehran, Iran
| | - Roxana Sasanfar
- Psychiatric and Neurodevelopmental Genetic Unit, Massachusetts General Hospital, Harvard Medical School, Boston, USA
| | - Maryam Eslami
- Department of Genetics, Tehran Medical Branch, Islamic Azad University, Tehran, Iran.,Applied Biotechnology Research Center, Tehran Medical Branch, Islamic Azad University, Tehran, Iran
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98
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Wonkam A, Lebeko K, Mowla S, Noubiap JJ, Chong M, Pare G. Whole exome sequencing reveals a biallelic frameshift mutation in GRXCR2 in hearing impairment in Cameroon. Mol Genet Genomic Med 2021; 9:e1609. [PMID: 33528103 PMCID: PMC8104159 DOI: 10.1002/mgg3.1609] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Revised: 01/06/2021] [Accepted: 01/11/2021] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND Hearing impairment (HI) genes are poorly studied in African populations. METHODS We used whole exome sequencing (WES) to investigate pathogenic and likely pathogenic (PLP) variants in 10 individuals with HI, from four multiplex families from Cameroon, two of which were previously unresolved with a targeted gene enrichment (TGE) panel of 116 genes. In silico protein modelling, western blotting and live imaging of transfected HEK293 cells were performed to study protein structure and functions. RESULTS All PLP variants previously identified with TGE were replicated. In one previously unresolved family, we found a homozygous frameshift PLP variant in GRXCR2 (OMIM: 615762), NM_001080516.1(GRXCR2):c.251delC p.(Ile85SerfsTer33), in two affected siblings; and additionally, in 1/80 unrelated individuals affected with non-syndromic hearing impairment (NSHI). The GRXCR2-c.251delC variant introduced a premature stop codon, leading to truncation and loss of a zinc-finger domain. Fluorescence confocal microscopy tracked the wild-type GRXCR2 protein to the cellular membrane, unlike the mutated GRXCR2 protein. CONCLUSION This study confirms GRXCR2 as a HI-associated gene. GRXCR2 should be included to the currently available TGE panels for HI diagnosis.
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Affiliation(s)
- Ambroise Wonkam
- Department of Medicine, Division of Human Genetics, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa.,Institute of Infectious Diseases and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Kamogelo Lebeko
- Department of Medicine, Division of Human Genetics, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Shaheen Mowla
- Department of Pathology, Division of Haematology, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Jean Jacques Noubiap
- Centre for Heart Rhythm Disorders, South Australian Health and Medical Research Institute (SAHMRI, University of Adelaide and Royal Adelaide Hospital, Adelaide, Australia
| | - Mike Chong
- Population Health Research Institute, Hamilton Health Sciences and McMaster University, Hamilton, ON, Canada
| | - Guillaume Pare
- Population Health Research Institute, Hamilton Health Sciences and McMaster University, Hamilton, ON, Canada
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99
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Garcia-Vega L, O’Shaughnessy EM, Albuloushi A, Martin PE. Connexins and the Epithelial Tissue Barrier: A Focus on Connexin 26. BIOLOGY 2021; 10:biology10010059. [PMID: 33466954 PMCID: PMC7829877 DOI: 10.3390/biology10010059] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Revised: 01/11/2021] [Accepted: 01/12/2021] [Indexed: 12/15/2022]
Abstract
Simple Summary Tissues that face the external environment are known as ‘epithelial tissue’ and form barriers between different body compartments. This includes the outer layer of the skin, linings of the intestine and airways that project into the lumen connecting with the external environment, and the cornea of the eye. These tissues do not have a direct blood supply and are dependent on exchange of regulatory molecules between cells to ensure co-ordination of tissue events. Proteins known as connexins form channels linking cells directly and permit exchange of small regulatory signals. A range of environmental stimuli can dysregulate the level of connexin proteins and or protein function within the epithelia, leading to pathologies including non-healing wounds. Mutations in these proteins are linked with hearing loss, skin and eye disorders of differing severity. As such, connexins emerge as prime therapeutic targets with several agents currently in clinical trials. This review outlines the role of connexins in epithelial tissue and how their dysregulation contributes to pathological pathways. Abstract Epithelial tissue responds rapidly to environmental triggers and is constantly renewed. This tissue is also highly accessible for therapeutic targeting. This review highlights the role of connexin mediated communication in avascular epithelial tissue. These proteins form communication conduits with the extracellular space (hemichannels) and between neighboring cells (gap junctions). Regulated exchange of small metabolites less than 1kDa aide the co-ordination of cellular activities and in spatial communication compartments segregating tissue networks. Dysregulation of connexin expression and function has profound impact on physiological processes in epithelial tissue including wound healing. Connexin 26, one of the smallest connexins, is expressed in diverse epithelial tissue and mutations in this protein are associated with hearing loss, skin and eye conditions of differing severity. The functional consequences of dysregulated connexin activity is discussed and the development of connexin targeted therapeutic strategies highlighted.
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100
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Natural Course of Residual Hearing with Reference to GJB2 and SLC26A4 Genotypes: Clinical Implications for Hearing Rehabilitation. Ear Hear 2021; 42:644-653. [PMID: 33928925 DOI: 10.1097/aud.0000000000000965] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Understanding the characteristics of residual hearing at low frequencies and its natural course in relation to molecular genetic etiology may be important in developing rehabilitation strategies. Thus, we aimed to explore the characteristics and natural course of residual hearing at low frequencies associated with the two most frequent deafness genes: GJB2 and SLC26A4. METHODS Initially, 53 GJB2 and 65 SLC26A4 subjects were enrolled, respectively. Only those whose audiograms exhibited hearing thresholds ≤70 dB at 250 and 500 Hz, and who had at least 1-year follow-up period between the first and last audiograms, were included. Collectively, the clinical characteristics of 14 ears from eight subjects with GJB2 variants, and 31 ears from 22 subjects with SLC26A4 variants fulfilled the strict criteria. In this study, a dropout rate refers to an incidence of dropping out of the cohort by cochlear implant surgery due to severe hearing deterioration. RESULTS Among the ears with complete serial audiogram data set, significant residual hearing at low frequencies at the time of inclusion was observed in 18.8% of those with GJB2 variants (15 out of 80 ears) and 42.6% of those with SLC26A4 variants (46 out of 108 ears), revealing a difference between two deafness genes. Subsequently, ears with SLC26A4 variants (11 of 46 ears, 23.9%) turned out to have a higher dropout rate for cochlear implantation due to hearing deterioration within the first year than those with GJB2 variants (1 of 15, 6.7%), albeit with no statistical significance. Throughout the follow-up period (mean: 37.2 ± 6.8, range: 12 to 80 months), deterioration of residual hearing at low frequencies at 250 Hz (dB HL/y) and 500 Hz (dB HL/y) of those with GJB2 variants exhibited 3.1 ± 1.3 (range: 0 to 15) and 5.2 ± 1.6 (range: 0 to 20), respectively, suggesting the deterioration of residual hearing in GJB2 variants was rather slow and gradual. Specifically, GJB2 p.Leu79Cysfs*3 show less remarkable residual hearing at low frequencies, but then a relatively stable nature. In contrast, SLC26A4 variants demonstrated a significantly higher dropout rate due to severe hearing deterioration requiring cochlear implantation compared with the GJB2 variants. This trend was observed not only in the first-year follow-up period but also in the follow-up periods thereafter. The p.His723Arg;c.919-2A>G genotype of SLC26A4, in particular, was associated with a high propensity for sudden hearing deterioration, as indicated by the dropout rate, which was as high as 46.2% for cochlear implantation due to hearing deterioration during the first year follow-up period. Furthermore, the dropout rate for cochlear implantation was observed in 7.1% of those with GJB2 variants (one out of 14 ears) and 30.3% of those with SLC26A4 variants (10 out of 33 ears) throughout the entire follow-up period. CONCLUSIONS Our results suggest that there is a difference with respect to the progressive nature of residual hearing at low frequencies between the two most common genes responsible for hearing loss, which may provide clinical implications of having individualized rehabilitation and timely intervention.
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