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Peres C, Mammano F. A Protocol for the Automated Assessment of Cutaneous Pathology in a Mouse Model of Hemichannel Dysfunction. Methods Mol Biol 2024; 2801:177-187. [PMID: 38578421 DOI: 10.1007/978-1-0716-3842-2_13] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/06/2024]
Abstract
In this chapter, we provide detailed instructions to perform quantitative reflectance imaging in a mouse model of a rare epidermal disorder caused by hyperactive connexin 26 hemichannels. Reflectance imaging is a versatile and powerful tool in dermatology, offering noninvasive, high-resolution insights into skin pathology, which is essential for both clinical practice and research. This approach offers several advantages and applications. Unlike traditional biopsy, reflectance imaging is noninvasive, allowing for real-time, in vivo examination of the skin. This is particularly valuable for monitoring chronic conditions or assessing the efficacy of treatments over time, enabling the detailed examination of skin morphology. This is crucial for identifying features of skin diseases such as cancers, inflammatory conditions, and infections. In therapeutic applications, reflectance imaging can be used to monitor the response of skin lesions to treatments. It can help in identifying the most representative area of a lesion for biopsy, thereby increasing the diagnostic accuracy. Reflectance imaging can also be used to diagnose and monitor inflammatory skin diseases, like psoriasis and eczema, by visualizing changes in skin structure and cellular infiltration. As the technology becomes more accessible, it has potential in telemedicine, allowing for remote diagnosis and monitoring of skin conditions. In academic settings, reflectance imaging can be a powerful research tool, enabling the study of skin pathology and the effects of novel treatments, including the development of monoclonal antibodies for therapeutic applications.
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Affiliation(s)
- Chiara Peres
- Institute of Biochemistry and Cell Biology, Italian National Research Council, Rome, Italy
- , Bologna, Italy
| | - Fabio Mammano
- Institute of Biochemistry and Cell Biology, Italian National Research Council, Rome, Italy.
- Department of Physics and Astronomy "G. Galilei", University of Padova, Padova, Italy.
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Ali-Nazari MM, Rahbar N, Haddadzade Niri H, Vasaghi-Gharamaleki B. Mefloquine-Induced Inner Ear Damage and Preventive Effects of Electrical Stimulation: An Electrophysiological Study. Audiol Neurootol 2023; 29:88-95. [PMID: 37607499 DOI: 10.1159/000531788] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2023] [Accepted: 06/15/2023] [Indexed: 08/24/2023] Open
Abstract
INTRODUCTION Mefloquine is an antimalarial medicine used to prevent and treat malaria. This medicine has some side effects, including ototoxicity. This study, which was designed in two phases, aimed to investigate the side effects of mefloquine and evaluate the preventive effects of electrical stimulation on these side effects. METHODS In the first phase, two doses of mefloquine (50 and 200 μM) were injected into male rats, and after 7 days, they were evaluated by an auditory brainstem response (ABR) test. In the second phase, electrical stimulation was applied for 10 days, and then a toxic dose of mefloquine was injected. Similar to the first phase of the study, the animals were evaluated by an ABR test after 7 days. RESULTS In the first phase, the results showed that a high dose of mefloquine increased the ABR threshold and wave I latency; however, these changes were not observed in the second phase. CONCLUSION Application of electrical stimulation could prevent the ototoxic effects of mefloquine. According to the findings of the present study, electrical stimulation can be used as a preconditioner to prevent the ototoxic effects of mefloquine.
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Affiliation(s)
- Mohammad Mahdi Ali-Nazari
- Rehabilitation Research Center, Department of Audiology, School of Rehabilitation Sciences, Iran University of Medical Sciences, Tehran, Iran,
| | - Nariman Rahbar
- Rehabilitation Research Center, Department of Audiology, School of Rehabilitation Sciences, Iran University of Medical Sciences, Tehran, Iran
| | - Hassan Haddadzade Niri
- Rehabilitation Research Center, Department of Audiology, School of Rehabilitation Sciences, Iran University of Medical Sciences, Tehran, Iran
| | - Behnoosh Vasaghi-Gharamaleki
- Rehabilitation Research Center, Department of Rehabilitation Basic Sciences, School of Rehabilitation Sciences, Iran University of Medical Sciences, Tehran, Iran
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Geden H, Seneldir L. Connexin 26 (GJB2) Mutations Associated with Congenital Hearing Loss in a Country of Different Migration Routes: Turkey. Indian J Otolaryngol Head Neck Surg 2023; 75:628-634. [PMID: 37206770 PMCID: PMC10188702 DOI: 10.1007/s12070-023-03672-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Accepted: 03/02/2023] [Indexed: 03/19/2023] Open
Abstract
To determine the prevalence of DFNB1 mutations containing GJB2 (connexin 26) genes with deletion 35delG mutation in congenital hearing loss, and to analyze this gene according to regional differences based on geographic and socio-economic relations in Turkish patients in Istanbul. Our study includes 51 unrelated children with non-syndromic sensorineural hearing impairment with the proof of clinical ABR results. Molecular studies were performed using PCR- Mediated Site-Directed Mutagenesis assay, PCR and direct sequencing to screen for GJB2 and 35delG mutations. Genomic DNA is obtained from the peripheral blood which is taken using a Qiagen DNA isolation kit. GJB2-35delG mutations were found in 25.5% of the patients; 19.6% were homozygous, 5.8% were heterozygous. The ratio of 35delG mutation detected in the children of families with consanguineous marriages and not; were 18.5% (n = 5) and 33.3% (n = 8) of cases respectively. The 35delG mutations in the patients whose father and mother were both from the Black Sea region were 43.18% (n = 19). Our results show that 35delG mutation is at a high frequency in our country, although it is more common in children of parents from the Black Sea region. Screening for the 35delG mutation in the GJB2 gene is the best choice for early diagnosis and emergency response plans for treatment and rehabilitation.
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Affiliation(s)
- Hakan Geden
- ENT Department, Sancaktepe Education and Research Hospital, Istanbul, Turkey
| | - Lütfü Seneldir
- ENT Department, Haydarpasa Numune Education and Research Hospital, Tıbbiye Cad. No: 40, Uskudar, 34722 Istanbul, Turkey
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Peres C, Sellitto C, Nardin C, Putti S, Orsini T, Di Pietro C, Marazziti D, Vitiello A, Calistri A, Rigamonti M, Scavizzi F, Raspa M, Zonta F, Yang G, White TW, Mammano F. Antibody gene transfer treatment drastically improves epidermal pathology in a keratitis ichthyosis deafness syndrome model using male mice. EBioMedicine 2023; 89:104453. [PMID: 36736132 PMCID: PMC9926223 DOI: 10.1016/j.ebiom.2023.104453] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Revised: 12/30/2022] [Accepted: 01/11/2023] [Indexed: 02/04/2023] Open
Abstract
BACKGROUND Keratitis ichthyosis deafness (KID) syndrome is a rare disorder caused by hemichannel (HC) activating gain-of-function mutations in the GJB2 gene encoding connexin (Cx) 26, for which there is no cure, or current treatments based upon the mechanism of disease causation. METHODS We applied Adeno Associated Virus (AAV) mediated mAb gene transfer (AAVmAb) to treat the epidermal features of KID syndrome with a well-characterized HC blocking antibody using male mice of a murine model that replicates the skin pathology of the human disease. FINDINGS We demonstrate that in vivo AAVmAb treatment significantly reduced the size and thickness of KID lesions, in addition to blocking activity of mutant HCs in the epidermis in vivo. We also show that AAVmAb treatment eliminated abnormal keratinocyte proliferation and enlarged cell size, decreased apoptosis, and restored the normal distribution of keratin expression. INTERPRETATION Our findings reinforce the critical role played by increased HC activity in the skin pathology associated with KID syndrome. They also underscore the clinical potential of anti-HC mAbs coupled with genetic based delivery systems for treating the underlying mechanistic basis of this disorder. Inhibition of HC activity is an ideal therapeutic target in KID syndrome, and the genetic delivery of mAbs targeted against mutant HCs could form the basis of new therapeutic interventions to treat this incurable disease. FUNDING Fondazione Telethon grant GGP19148 and University of Padova grant Prot. BIRD187130 to FM; Foundation for Ichthyosis and Related Skin Types (FIRST) and National Institutes of Health grant EY 026911 to TWW.
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Affiliation(s)
- Chiara Peres
- Institute of Biochemistry and Cell Biology, Italian National Research Council, 00015 Monterotondo, Rome, Italy
| | - Caterina Sellitto
- Department of Physiology and Biophysics, Stony Brook University, T5-147, Basic Science Tower; Stony Brook, NY, 11794-8661, USA
| | - Chiara Nardin
- Institute of Biochemistry and Cell Biology, Italian National Research Council, 00015 Monterotondo, Rome, Italy
| | - Sabrina Putti
- Institute of Biochemistry and Cell Biology, Italian National Research Council, 00015 Monterotondo, Rome, Italy
| | - Tiziana Orsini
- Institute of Biochemistry and Cell Biology, Italian National Research Council, 00015 Monterotondo, Rome, Italy
| | - Chiara Di Pietro
- Institute of Biochemistry and Cell Biology, Italian National Research Council, 00015 Monterotondo, Rome, Italy
| | - Daniela Marazziti
- Institute of Biochemistry and Cell Biology, Italian National Research Council, 00015 Monterotondo, Rome, Italy
| | - Adriana Vitiello
- Department of Molecular Medicine, University of Padova, 35121, Padova, Italy
| | - Arianna Calistri
- Department of Molecular Medicine, University of Padova, 35121, Padova, Italy
| | | | - Ferdinando Scavizzi
- Institute of Biochemistry and Cell Biology, Italian National Research Council, 00015 Monterotondo, Rome, Italy
| | - Marcello Raspa
- Institute of Biochemistry and Cell Biology, Italian National Research Council, 00015 Monterotondo, Rome, Italy
| | - Francesco Zonta
- Shanghai Institute for Advanced Immunochemical Studies, ShanghaiTech University, Shanghai, 201210, China
| | - Guang Yang
- Shanghai Institute for Advanced Immunochemical Studies, ShanghaiTech University, Shanghai, 201210, China
| | - Thomas W White
- Department of Physiology and Biophysics, Stony Brook University, T5-147, Basic Science Tower; Stony Brook, NY, 11794-8661, USA.
| | - Fabio Mammano
- Institute of Biochemistry and Cell Biology, Italian National Research Council, 00015 Monterotondo, Rome, Italy; Department of Physics and Astronomy "G. Galilei", University of Padova, 35131, Padova, Italy.
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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Reis CS, Santos AC, Barros H, Fernandes S, Moura CP. GJB2: Frequency of the Less Common Variants in a Sample of the Portuguese Population. ACTA MEDICA PORT 2021; 34:592-600. [PMID: 34032567 DOI: 10.20344/amp.13781] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Revised: 12/30/2020] [Accepted: 01/11/2021] [Indexed: 11/20/2022]
Abstract
INTRODUCTION Sequence variants in the GJB2 gene account for up to 50% of cases of non-syndromic sensorineural hearing loss in the Caucasian population. In this study, we report the frequency of the less common variants of the GJB2 gene in a Portuguese sample and compare these frequencies with those of a group of hearing-impaired patients. MATERIAL AND METHODS In order to select the less common GJB2 variants, 147 hearing-impaired patients followed in Centro Hospitalar Universitário de São João were evaluated. Afterwards, the presence of those variants was tested in 360 individuals from Generation 21. RESULTS The patient assessment enabled the selection of 11 GJB2 variants. Of those, 10 were investigated in Generation 21 participants, with only four being detected, in heterozygosity: p.Phe83Leu, p.Arg127His, p.Val153Ile and p.Asn206Ser, with the allelic frequencies (95% confidence interval) of 0.14% (0.01% - 0.87%), 0.28% (0.01% - 1.08%), 0.97% (0.43% - 2.04%) and 0.14% (0.01% - 0.88%), respectively. Two variants, p.Val37Ile and p.Val95Met, were more frequent in the patients' group with statistical significance. DISCUSSION Our results allow for the p.Arg127His and p.Val153Ile variants to comply with polymorphism criteria and support the pathogenicity of p.Val37Ile and p.Val95Met variants. Moreover, two cases of moderate hearing loss were explained by the p.Val37Ile/p. Asn206Ser genotype, substantiating both the pathogenicity of such variants and the hypothesis that compound heterozygosity with p.Ans206Ser is associated with mild-moderate genotypes. CONCLUSION Understanding the role of the variants is essential in order to provide genetic counselling to patients and their families. We explored a set of uncommon GJB2 variants that comprised 12% of the hearing-impaired patients in this study, supporting the relevance of their description.
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Affiliation(s)
| | - Ana Cristina Santos
- Department of Public Health and Forensic Sciences, and Medical Education. Faculty of Medicine. University of Porto. Porto. Instituto de Saúde Pública. Universidade do Porto. Porto. Portugal
| | - Henrique Barros
- Department of Public Health and Forensic Sciences, and Medical Education. Faculty of Medicine. University of Porto. Porto. Instituto de Saúde Pública. Universidade do Porto. Porto. Portugal
| | - Susana Fernandes
- Genetics Unit. Department of Pathology. Faculty of Medicine. University of Porto. Centro Hospitalar Universitário de São João. Porto. Instituto de Investigação e Inovação em Saúde. Universidade do Porto. Porto. Portugal
| | - Carla Pinto Moura
- Genetics Unit. Department of Pathology. Faculty of Medicine. University of Porto. Centro Hospitalar Universitário de São João. Porto. Instituto de Investigação e Inovação em Saúde. Universidade do Porto. Porto. Department of Otorhinolaryngology. Centro Hospitalar Universitário de São João. Porto. Portugal
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Sun M, Li Y, Qian J, Ding S, Sun M, Tan B, Zhao Y. Connexin26 Modulates the Radiosensitivity of Cutaneous Squamous Cell Carcinoma by Regulating the Activation of the MAPK/NF-κB Signaling Pathway. Front Cell Dev Biol 2021; 9:672571. [PMID: 34291047 PMCID: PMC8287175 DOI: 10.3389/fcell.2021.672571] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Accepted: 05/27/2021] [Indexed: 11/25/2022] Open
Abstract
Previous studies have confirmed that the gap junction protein Connexin26 (Cx26) is specifically expressed in human skin tissue. Cx26 can transmit radiation-induced damage signals. However, no study has yet reported whether Cx26 expression affects the radiosensitivity of human skin squamous cancer cells or the mechanism by which this occurs. In this study, we found that human skin squamous cell carcinoma cells (A431 cells) expressed significantly more Cx26 and were more sensitive to radiation compared to normal human keratinocytes (HaCaT cells). Knockdown of Cx26 in A431 cells (A431Cx26-/-) decreased radiosensitivity relative to control cells and altered the expression of key proteins in the MAPK and NF-κB signaling pathways. These results demonstrate that Cx26 expression might play an important role in mediating radiation damage in A431 cells and could serve as a potential target for clinical radiotherapy for cutaneous squamous cell carcinoma.
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Affiliation(s)
- Minqiong Sun
- Teaching and Research Section of Nuclear Medicine, School of Basic Medical Sciences, Anhui Medical University, Hefei, China
| | - Yuan Li
- Teaching and Research Section of Nuclear Medicine, School of Basic Medical Sciences, Anhui Medical University, Hefei, China
| | - Jing Qian
- Teaching and Research Section of Nuclear Medicine, School of Basic Medical Sciences, Anhui Medical University, Hefei, China
| | - Siwei Ding
- Teaching and Research Section of Nuclear Medicine, School of Basic Medical Sciences, Anhui Medical University, Hefei, China
| | - Mingyu Sun
- Teaching and Research Section of Nuclear Medicine, School of Basic Medical Sciences, Anhui Medical University, Hefei, China
- Center of Medical Physics and Technology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei, China
| | - Bowen Tan
- Teaching and Research Section of Nuclear Medicine, School of Basic Medical Sciences, Anhui Medical University, Hefei, China
| | - Ye Zhao
- Teaching and Research Section of Nuclear Medicine, School of Basic Medical Sciences, Anhui Medical University, Hefei, China
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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Maslova EA, Orishchenko KE, Posukh OL. Functional Evaluation of a Rare Variant c.516G>C (p.Trp172Cys) in the GJB2 ( Connexin 26) Gene Associated with Nonsyndromic Hearing Loss. Biomolecules 2021; 11:61. [PMID: 33466560 PMCID: PMC7824951 DOI: 10.3390/biom11010061] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Revised: 01/03/2021] [Accepted: 01/04/2021] [Indexed: 01/05/2023] Open
Abstract
Mutations in the GJB2 gene encoding transmembrane protein connexin 26 (Cx26) are the most common cause for hearing loss worldwide. Cx26 plays a crucial role in the ionic and metabolic homeostasis in the inner ear, indispensable for normal hearing process. Different pathogenic mutations in the GJB2 gene can affect all stages of the Cx26 life cycle and result in nonsyndromic autosomal recessive (DFNB1) or dominant (DFNA3) deafness and syndromes associating hearing loss with skin disorders. This study aims to elucidate the functional consequences of a rare GJB2 variant c.516G>C (p.Trp172Cys) found with high frequency in deaf patients from indigenous populations of Southern Siberia (Russia). The substitution c.516G>C leads to the replacement of tryptophan at a conserved amino acid position 172 with cysteine (p.Trp172Cys) in the second extracellular loop of Cx26 protein. We analyzed the subcellular localization of mutant Cx26-p.Trp172Cys protein by immunocytochemistry and the hemichannels permeability by dye loading assay. The GJB2 knockout HeLa cell line has been generated using CRISPR/Cas9 genome editing tool. Subsequently, the HeLa transgenic cell lines stably expressing different GJB2 variants (wild type and mutations associated with hearing loss) were established based on knockout cells and used for comparative functional analysis. The impaired trafficking of mutant Cx26-p.Trp172Cys protein to the plasma membrane and reduced hemichannels permeability support the pathogenic effect of the c.516G>C (p.Trp172Cys) variant and its association with nonsyndromic hearing loss. Our data contribute to a better understanding of the role of mutations in the second extracellular loop of Cx26 protein in pathogenesis of deafness.
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Affiliation(s)
- Ekaterina A. Maslova
- Federal Research Center Institute of Cytology and Genetics, Siberian Branch of the Russian Academy of Sciences, Novosibirsk 630090, Russia; (E.A.M.); (K.E.O.)
- Novosibirsk State University, Novosibirsk 630090, Russia
| | - Konstantin E. Orishchenko
- Federal Research Center Institute of Cytology and Genetics, Siberian Branch of the Russian Academy of Sciences, Novosibirsk 630090, Russia; (E.A.M.); (K.E.O.)
- Novosibirsk State University, Novosibirsk 630090, Russia
| | - Olga L. Posukh
- Federal Research Center Institute of Cytology and Genetics, Siberian Branch of the Russian Academy of Sciences, Novosibirsk 630090, Russia; (E.A.M.); (K.E.O.)
- Novosibirsk State University, Novosibirsk 630090, Russia
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Al-janabi AM, Ahmmed HS, Al-Khafaji SM. Connexin 26 (GJB2) gene mutations linked with autosomal recessive non-syndromic sensor neural hearing loss in the Iraqi population. J Med Life 2021; 14:841-846. [PMID: 35126756 PMCID: PMC8811675 DOI: 10.25122/jml-2021-0152] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Accepted: 09/08/2021] [Indexed: 11/19/2022] Open
Abstract
Deafness is a total or partial hearing loss that may appear at any age and with different degrees of severity. Approximately 50% of hearing loss have a genetic origin, and among them, non-syndromic sensorineural deafness represents about 70% of the cases. From them, 80% correspond to autosomal recessive inheritance deafness. Autosomal recessive deafness was not studied enough at the molecular level in Iraq. This study aimed to verify the frequency of three GJB2 mutations in non-syndromic sensorineural deafness in the Iraqi population. The current case-control study was conducted from January 2018 to January 2020. The study included 95 deafness patients (55 males and 40 females) and 110 healthy control group. Age and sex were matched between the two groups. In order to detect c.35delG, 235delC, and 167delT mutations in the GJB2 gene, we employed the PCR-RFLP technique. The c.35delG was the main frequent mutation encountered with the GJB2 gene among patients with autosomal recessive non-syndromic sensorineural hearing loss. Among them, 35 (36.8%) were homozygous, 40 (42.1%) were heterozygous, and 20 (21.1%) were wild genotypes. The second-degree mutation in the GJB2 gene was c.235delC mutation, which from the 95 deaf patients, there were 20 (21.1%) with homozygous, 33 (34.7%) heterozygous, and 42 (44.2%) wild genotypes. None of the 95 deaf patients showed the c.167delT mutation, and no mutations appeared in the control group. Our data concluded that the GJB2 c.35delG and c.235delC gene mutations were the main cause of autosomal recessive non-syndromic sensorineural hearing loss in the Iraqi deaf population.
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Affiliation(s)
- Anwar Madlool Al-janabi
- Department of Clinical Chemistry, College of Medicine, University of Kufa, Najaf, Iraq,* Corresponding Author: Anwar Madlool Al-janabi, Department of Clinical Chemistry, College of Medicine, University of Kufa, Najaf, Iraq. E-mail:
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11
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Defourny J, Thiry M. Tricellular adherens junctions provide a cell surface delivery platform for connexin 26/30 oligomers in the cochlea. Hear Res 2020; 400:108137. [PMID: 33291008 DOI: 10.1016/j.heares.2020.108137] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Revised: 11/12/2020] [Accepted: 11/25/2020] [Indexed: 12/13/2022]
Abstract
In the cochlea, connexins 26 (Cx26) and 30 (Cx30) largely co-assemble into heteromeric gap junctions, which connect adjacent non-sensory epithelial cells. These channels are believed to ensure the rapid removal of K+ away from the base of sensory hair cells, resulting in K+ recycling back to the endolymph to maintain cochlear homeostasis. Many of the mutations in GJB2 and GJB6, which encode CX26 and CX30, impair the formation of membrane channels and cause autosomal hearing loss in humans. Although recent advances have been made, several important questions remain about connexin trafficking and gap junction biogenesis. Here we show that tricellular adherens junctions present at the crossroad between adjacent gap junction plaques, provide an unexpected cell surface delivery platform for Cx26/Cx30 oligomers. Using an in situ proximity ligation assay, we detected the presence of non-junctional Cx26/Cx30 oligomers within lipid raft-enriched tricellular junction sites. In addition, we observed that cadherin homophilic interactions are critically involved in microtubule-mediated trafficking of Cx26/Cx30 oligomers to the cell surface. Overall, our results unveil an unexpected role for tricellular junctions in the trafficking and assembly of membrane channels.
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Affiliation(s)
- Jean Defourny
- GIGA-Neurosciences, Unit of Cell and Tissue Biology, University of Liège, C.H.U B36, B-4000 Liège, Belgium.
| | - Marc Thiry
- GIGA-Neurosciences, Unit of Cell and Tissue Biology, University of Liège, C.H.U B36, B-4000 Liège, Belgium
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Asgari T, Naji M, Mansouri P, Mahmoudi H, Zabihi M, Youssefian L, Mahdavi M, Naraghi ZS, Zeinali S, Vahidnezhad H, Uitto J. Keratitis-ichthyosis-deafness syndrome: Phenotypic heterogeneity and treatment perspective of patients with p.Asp50Asn GJB2 mutation. Dermatol Ther 2020; 33:e14493. [PMID: 33136289 DOI: 10.1111/dth.14493] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Accepted: 10/26/2020] [Indexed: 11/29/2022]
Abstract
Keratitis-ichthyosis-deafness (KID) syndrome is caused by mutations in the GJB2 gene encoding connexin 26, a component of transmembrane hemichannels which form gap junction channels, critical for cell-cell communication. Here, we report two patients from two distinct families with KID syndrome with the same GJB2 mutation (p.Asp50Asn); in both cases the mutation was de novo, as the parents depicted the wild-type allele only. The patients' cutaneous manifestations were strikingly different illustrating the wide spectrum of phenotype of these patients, even with the same GJB2 mutation. One of the patients was treated with acitretin with dramatic improvement in his skin findings, illustrating the role of oral acitretin in treatment of patients with KID syndrome. Collectively, these patients attest to the phenotypic spectrum of KID syndrome, with therapeutic perspective.
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Affiliation(s)
- Tina Asgari
- Department of Biology, Science, and Research Branch, Islamic Azad University, Tehran, Iran
| | - Mahtab Naji
- Department of Dermatology and Cutaneous Biology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania, USA.,Jefferson Institute of Molecular Medicine, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Parvin Mansouri
- Skin and Stem Cell Research Center, Tehran University of Medical Sciences, Tehran, Iran
| | - Hamidreza Mahmoudi
- Department of Dermatology, Tehran University of Medical Sciences, Razi Hospital, Tehran, Iran
| | | | - Leila Youssefian
- Department of Dermatology and Cutaneous Biology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania, USA.,Jefferson Institute of Molecular Medicine, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Mohammadreza Mahdavi
- Thalassemia Research Center, Mazandaran University of Medical Sciences, Sari, Iran
| | - Zahra Safaei Naraghi
- Departments of Dermatology and Pathology, Tehran University of Medical Sciences, Razi Hospital, Tehran, Iran
| | - Sirous Zeinali
- Kawsar Human Genetics Research Center, Tehran, Iran.,Department of Molecular Medicine, Biotechnology Research Center, Pasteur Institute of Iran, Tehran, Iran
| | - Hassan Vahidnezhad
- Department of Dermatology and Cutaneous Biology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania, USA.,Jefferson Institute of Molecular Medicine, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Jouni Uitto
- Department of Dermatology and Cutaneous Biology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania, USA.,Jefferson Institute of Molecular Medicine, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
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Moon PK, Qian JZ, McKenna E, Xi K, Rowe NC, Ng NN, Zheng J, Tam LT, MacEachern SJ, Ahmad I, Cheng AG, Forkert ND, Yeom KW. Cerebral volume and diffusion MRI changes in children with sensorineural hearing loss. Neuroimage Clin 2020; 27:102328. [PMID: 32622314 PMCID: PMC7334366 DOI: 10.1016/j.nicl.2020.102328] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Revised: 06/19/2020] [Accepted: 06/20/2020] [Indexed: 12/11/2022]
Abstract
Microstructural and macrostructural changes in sensorineural hearing loss. Magnetic resonance imaging as tool to assess cerebral volume and diffusion. Greater diffusion in cortex, thalamus, caudate, brainstem with hearing loss. Smaller brainstem volume with hearing loss. Connexin 26, Pendrin mutations show diffusion changes in brainstem and thalamus.
Purpose Sensorineural hearing loss (SNHL) is the most prevalent congenital sensory deficit in children. Information regarding underlying brain microstructure could offer insight into neural development in deaf children and potentially guide therapies that optimize language development. We sought to quantitatively evaluate MRI-based cerebral volume and gray matter microstructure children with SNHL. Methods & Materials We conducted a retrospective study of children with SNHL who obtained brain MRI at 3 T. The study cohort comprised 63 children with congenital SNHL without known focal brain lesion or structural abnormality (33 males; mean age 5.3 years; age range 1 to 11.8 years) and 64 age-matched controls without neurological, developmental, or MRI-based brain macrostructure abnormality. An atlas-based analysis was used to extract quantitative volume and median diffusivity (ADC) in the following brain regions: cerebral cortex, thalamus, caudate, putamen, globus pallidus, hippocampus, amygdala, nucleus accumbens, brain stem, and cerebral white matter. SNHL patients were further stratified by severity scores and hearing loss etiology. Results Children with SNHL showed higher median ADC of the cortex (p = .019), thalamus (p < .001), caudate (p = .005), and brainstem (p = .003) and smaller brainstem volumes (p = .007) compared to controls. Patients with profound bilateral SNHL did not show any significant differences compared to patients with milder bilateral SNHL, but both cohorts independently had smaller brainstem volumes compared to controls. Children with unilateral SNHL showed greater amygdala volumes compared to controls (p = .021), but no differences were found comparing unilateral SNHL to bilateral SNHL. Based on etiology for SNHL, patients with Pendrin mutations showed higher ADC values in the brainstem (p = .029, respectively); patients with Connexin 26 showed higher ADC values in both the thalamus (p < .001) and brainstem (p < .001) compared to controls. Conclusion SNHL patients showed significant differences in diffusion and volume in brain subregions, with region-specific findings for patients with Connexin 26 and Pendrin mutations. Future longitudinal studies could examine macro- and microstructure changes in children with SNHL over development and potential predictive role for MRI after interventions including cochlear implant outcome.
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Affiliation(s)
- Peter K Moon
- Stanford University School of Medicine, Stanford, CA, USA
| | - Jason Z Qian
- Department of Otolaryngology-Head and Neck Surgery, Stanford University, Stanford, CA, USA
| | - Emily McKenna
- Department of Radiology, Lucile Packard Children's Hospital, Stanford University, Stanford, CA, USA
| | - Kevin Xi
- Department of Radiology, Lucile Packard Children's Hospital, Stanford University, Stanford, CA, USA
| | - Nathan C Rowe
- Department of Radiology, University of Calgary, Calgary, Alberta, Canada
| | - Nathan N Ng
- Stanford University School of Medicine, Stanford, CA, USA
| | - Jimmy Zheng
- Stanford University School of Medicine, Stanford, CA, USA
| | - Lydia T Tam
- Stanford University School of Medicine, Stanford, CA, USA
| | - Sarah J MacEachern
- Department of Pediatrics, University of Calgary, Calgary, Alberta, Canada
| | - Iram Ahmad
- Department of Otolaryngology-Head and Neck Surgery, Stanford University, Stanford, CA, USA
| | - Alan G Cheng
- Department of Otolaryngology-Head and Neck Surgery, Stanford University, Stanford, CA, USA
| | - Nils D Forkert
- Department of Radiology, University of Calgary, Calgary, Alberta, Canada
| | - Kristen W Yeom
- Department of Radiology, Lucile Packard Children's Hospital, Stanford University, Stanford, CA, USA.
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Bussini A, Righi R, Pessina C, Genoni A, Cristofari E, Meli A, Granata P, Meroni E, Broccolo F, Casalone R. The p.Gly130Val mutation in the GJB2 gene: A familiar case of autosomal dominant non-syndromic hearing loss. Int J Pediatr Otorhinolaryngol 2019; 127:109653. [PMID: 31472357 DOI: 10.1016/j.ijporl.2019.109653] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/09/2019] [Revised: 08/01/2019] [Accepted: 08/20/2019] [Indexed: 11/27/2022]
Abstract
Several forms of sensorineural hearing loss (SNHL) have been imputated to connexins mutations and prevalently to connexin 26 (Cx26), codified by the GJB2 gene (gap junction protein, beta 2). Here, we report the first familiar case (heterozygous p. G130V mutation) of non-syndromic (without any dermatological manifestation) dominant profound SNHL. Proband was a 6-years-old male with post-lingual bilateral profound SNHL, clinically identified at the age of 3 with diagnosis of severe SNHL. We confirm that the p. G130V variant of the GJB2 gene is causative of autosomal dominant form of SNHL, although it is not always associated with the presence of skin diseases.
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Affiliation(s)
- Adelaide Bussini
- Unit of Cytogenetics and Medical Genetic, ASST Settelaghi, Varese, Italy
| | - Rossana Righi
- Unit of Cytogenetics and Medical Genetic, ASST Settelaghi, Varese, Italy
| | - Chiara Pessina
- Unit of Cytogenetics and Medical Genetic, ASST Settelaghi, Varese, Italy
| | - Angelo Genoni
- Unit of Cytogenetics and Medical Genetic, ASST Settelaghi, Varese, Italy
| | | | | | - Paola Granata
- Unit of Cytogenetics and Medical Genetic, ASST Settelaghi, Varese, Italy
| | - Emanuela Meroni
- Unit of Cytogenetics and Medical Genetic, ASST Settelaghi, Varese, Italy
| | - Francesco Broccolo
- Department of Medicine and Surgery (School of Medicine), University of Milano-Bicocca, Monza, Italy.
| | - Rosario Casalone
- Unit of Cytogenetics and Medical Genetic, ASST Settelaghi, Varese, Italy.
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15
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Guerra L, Bergamo F, D'Apice MR, Angelucci F, di Girolamo S, Camerota L, Monetta R, Annessi G, Castiglia D, Novelli G, Paradisi M, Brancati F. Keratoderma-Deafness-Mucocutaneous Syndrome Associated with Phe142Leu in the GJB2 Gene. Acta Derm Venereol 2019; 99:1192-1194. [PMID: 31408183 DOI: 10.2340/00015555-3291] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Affiliation(s)
- Liliana Guerra
- Laboratory of Molecular and Cell Biology, Istituto Dermopatico dell'Immacolata, IDI-IRCCS, Via dei Monti di Creta, 104, IT-00167 Rome, Italy
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Stylianaki EA, Karpouzis A, Tripsianis G, Veletza S. Assessment of Gap Junction Protein Beta-2 rs3751385 Gene Polymorphism in Psoriasis Vulgaris. J Clin Med Res 2019; 11:642-650. [PMID: 31523338 PMCID: PMC6731047 DOI: 10.14740/jocmr3845] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2019] [Accepted: 06/25/2019] [Indexed: 02/05/2023] Open
Abstract
Background Gap junction protein beta 2 (GJB2) upregulation in psoriasis transcriptome analysis as well as connexin 26 (Cx26, encoded by GJB2) expression upregulation in psoriatic plaques has already been substantiated. GJB2 rs72474224 and rs3751385 have been correlated with psoriasis vulgaris incidence in Chinese populations. Here we study the effect of rs3751385 in patients suffering from psoriasis vulgaris in a Caucasian Greek population at the prefecture of Thrace in Northern Greece. Methods One hundred and seventy-three (111 males and 62 females) psoriatic patients (108 were of early-onset psoriasis) and 171 matched controls were included in the study. Genomic DNA was extracted from peripheral blood leukocytes and genotyping was carried out by polymerase chain reaction-restriction-fragment length polymorphism (PCR-RFLP). Results A statistically significant lower frequency of C/T genotype in late-onset male psoriasis vulgaris (P = 0.029) as well as of T allele in female early-onset psoriasis vulgaris (P = 0.049) were ascertained. Conclusions On condition that all other genetic or environmental factors remain stable, the existence and possible interaction between GJB2 rs3751385 C and T alleles in male psoriatic patients may be considered as protective gene component against late-onset psoriasis appearance, while presence of the T allele in female might block the histogenetic mechanisms of early-onset psoriasis lesions.
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Affiliation(s)
- Elli-Anna Stylianaki
- Department of Biology, Faculty of Medicine, Democritus University of Thrace, Alexandroupolis, Greece
| | - Anthony Karpouzis
- Department of Dermatology, Faculty of Medicine, Democritus University of Thrace, Alexandroupolis, Greece
| | - Gregory Tripsianis
- Department of Medical Statistics, Faculty of Medicine, Democritus University of Thrace, Alexandroupolis, Greece
| | - Stavroula Veletza
- Department of Biology, Faculty of Medicine, Democritus University of Thrace, Alexandroupolis, Greece
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Talbi S, Bonnet C, Boudjenah F, Mansouri MT, Petit C, Ammar Khodja F. The spectrum of GJB2 gene mutations in Algerian families with nonsyndromic hearing loss from Sahara and Kabylie regions. Int J Pediatr Otorhinolaryngol 2019; 124:157-160. [PMID: 31200317 DOI: 10.1016/j.ijporl.2019.05.036] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/25/2019] [Revised: 05/23/2019] [Accepted: 05/23/2019] [Indexed: 01/14/2023]
Abstract
INTRODUCTION DFNB1, caused by mutations of GJB2 or GJB6, is the most prevalent genetic form of nonsyndromic (i.e., isolated) congenital deafness in countries located around the Mediterranean Sea. Because some mutations are restricted to specific ethnic-geographic groups, we studied the prevalence and spectrum of GJB2/GJB6 mutations in deaf patients originating from two different Algerian regions, Kabylie and Sahara. PATIENTS AND METHODS Among 91 reportedly unrelated Algerian patients affected by prelingual deafness, 80 patients (41 from Kabylie and 39 from Sahara) were diagnosed with isolated deafness. All had profound deafness, except one patient with mild deafness. They were screened for the presence of GJB2 mutations by direct sequencing of the single coding exon of GJB2. Patients without mutations were then screened for the presence of the most frequent two deletions of GJB6: del(GJB6-D13S1854) and del(GJB6-D13S1830). RESULTS Causative mutations were found in 13 and 8 patients from Kabylie and Sahara, respectively, accounting for more than a quarter of the cohort. The c.35delG, p.Gly12Valfs*2 mutation remains the most important mutation both in Kabylie (10 patients) and Sahara (7 patients). All detected patients were homozygous for this mutation. In addition, two other mutations (c.139G > T, p.Glu47* and c.167delT, p.Leu56Argfs*26) were found homozygous in one family each, and two patients were compound heterozygotes for (c.35delG p.Gly12Valfs*2/c.139G > T, p.Glu47*). No deletion of GJB6 was detected. CONCLUSION We confirm that mutations in GJB2, mainly c.35delG, are one of the most prevalent causes of nonsyndromic congenital deafness in Algeria, whereas the del (GJB6-D13S1854) and del (GJB6-D13S1830) deletions of GJB6 contribute little, if any. Further investigation is needed to identify the cause of deafness in other patients without diagnostic.
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Affiliation(s)
- Sonia Talbi
- Equipe de Génétique, Laboratoire de Biologie Cellulaire et Moléculaire, Faculté des Sciences Biologiques, Université des Sciences et de la Technologie Houari Boumediene (USTHB), POB32 ElAlia, 16111, Bab Ezzouar, Alger, Algeria.
| | - Crystel Bonnet
- Inserm UMRS 1120, Institut de la Vision, Sorbonne Université, Paris, France
| | - Farid Boudjenah
- Service d'Otorhinolaryngologie (ORL), Hôpital de Frantz fanon, Bejaia, Algeria; Service d'Otorhinolaryngologie (ORL), Hôpital Sidi Belloua, Tizi-Ouzou, Algeria
| | | | - Christine Petit
- Inserm UMRS 1120, Institut de la Vision, Sorbonne Université, Paris, France; Institut Pasteur, Collège de France, Paris, France
| | - Fatima Ammar Khodja
- Equipe de Génétique, Laboratoire de Biologie Cellulaire et Moléculaire, Faculté des Sciences Biologiques, Université des Sciences et de la Technologie Houari Boumediene (USTHB), POB32 ElAlia, 16111, Bab Ezzouar, Alger, Algeria
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Abstract
OBJECTIVE To determine the prevalence and spectrum of Connexin 26 (GJB2) mutations in pre-lingual non-syndromic hearing loss (NSHL) patients in authors' centre and to review the data of Indian patients from the literature. METHODS Sanger sequencing of entire coding region contained in single exon (Exon 2) of GJB2 gene in 15 patients of NSHL. RESULTS GJB2 mutations were found in 40% (6/15) of NSHL patients, out of which mono-allelic were 33.3% (2/6). Bi-allelic GJB2 mutations were identified in 4 of 6 patients. Most common GJB2 mutation identified was c.71G > A(p.W24X), comprising 30% of the total GJB2 mutant alleles. Six studies involving 1119 patients with NSHL were reviewed and 4 of them have reported c.71G > A(p.W24X) as the commonest mutation while 2 studies found c.35delG as the commonest. GJB2 mutations accounted for 10.9%-36% cases of NSHL. Sixteen other mutations in GJB2 gene were reported in Indian patients out of which 6 mutations other than c.71G > A(p.W24X) viz., c.35delG, c.1A > G(p.M1V), c.127G > A(p.V43 M), c.204C > G(p.Y86X), c.231G > A(p.W77X) and c.439G > A(p.E147K) were identified in the present study. CONCLUSIONS Connexin 26 (GJB2) mutations are responsible for 19.4% of NSHL in Indian population. The c.71G > A(W24X) and c.35delG were the most prevalent GJB2 mutations accounting for 72.2% (234 of 324 total mutated alleles from 7 studies) and 15.4% (50 of 324 total mutated alleles from 7 studies) respectively. Thus, screening of these two common mutations in GJB2 gene by polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP) would greatly help in providing easy genetic diagnosis and help in genetic counseling of the families with NSHL.
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Fetoni AR, Zorzi V, Paciello F, Ziraldo G, Peres C, Raspa M, Scavizzi F, Salvatore AM, Crispino G, Tognola G, Gentile G, Spampinato AG, Cuccaro D, Guarnaccia M, Morello G, Van Camp G, Fransen E, Brumat M, Girotto G, Paludetti G, Gasparini P, Cavallaro S, Mammano F. Cx26 partial loss causes accelerated presbycusis by redox imbalance and dysregulation of Nfr2 pathway. Redox Biol 2018; 19:301-317. [PMID: 30199819 PMCID: PMC6129666 DOI: 10.1016/j.redox.2018.08.002] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Revised: 07/26/2018] [Accepted: 08/05/2018] [Indexed: 11/29/2022] Open
Abstract
Mutations in GJB2, the gene that encodes connexin 26 (Cx26), are the most common cause of sensorineural hearing impairment. The truncating variant 35delG, which determines a complete loss of Cx26 protein function, is the prevalent GJB2 mutation in several populations. Here, we generated and analyzed Gjb2+/- mice as a model of heterozygous human carriers of 35delG. Compared to control mice, auditory brainstem responses (ABRs) and distortion product otoacoustic emissions (DPOAEs) worsened over time more rapidly in Gjb2+/- mice, indicating they were affected by accelerated age-related hearing loss (ARHL), or presbycusis. We linked causally the auditory phenotype of Gjb2+/- mice to apoptosis and oxidative damage in the cochlear duct, reduced release of glutathione from connexin hemichannels, decreased nutrient delivery to the sensory epithelium via cochlear gap junctions and deregulated expression of genes that are under transcriptional control of the nuclear factor erythroid 2-related factor 2 (Nrf2), a pivotal regulator of tolerance to redox stress. Moreover, a statistically significant genome-wide association with two genes (PRKCE and TGFB1) related to the Nrf2 pathway (p-value < 4 × 10-2) was detected in a very large cohort of 4091 individuals, originating from Europe, Caucasus and Central Asia, with hearing phenotype (including 1076 presbycusis patients and 1290 healthy matched controls). We conclude that (i) elements of the Nrf2 pathway are essential for hearing maintenance and (ii) their dysfunction may play an important role in the etiopathogenesis of human presbycusis.
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Affiliation(s)
- Anna Rita Fetoni
- CNR Institute of Cell Biology and Neurobiology, Monterotondo 00015, Italy; Università Cattolica del Sacro Cuore, Largo F. Vito 1, 00168 Rome, Italy; Institute of Otolaryngology, Fondazione Policlinico Universitario A. Gemelli IRCCS, Largo F. Vito 1, 00168 Rome, Italy
| | - Veronica Zorzi
- CNR Institute of Cell Biology and Neurobiology, Monterotondo 00015, Italy; Università Cattolica del Sacro Cuore, Largo F. Vito 1, 00168 Rome, Italy
| | - Fabiola Paciello
- CNR Institute of Cell Biology and Neurobiology, Monterotondo 00015, Italy; Università Cattolica del Sacro Cuore, Largo F. Vito 1, 00168 Rome, Italy
| | - Gaia Ziraldo
- CNR Institute of Cell Biology and Neurobiology, Monterotondo 00015, Italy; Università Cattolica del Sacro Cuore, Largo F. Vito 1, 00168 Rome, Italy
| | - Chiara Peres
- CNR Institute of Cell Biology and Neurobiology, Monterotondo 00015, Italy
| | - Marcello Raspa
- CNR Institute of Cell Biology and Neurobiology, Monterotondo 00015, Italy
| | | | | | - Giulia Crispino
- CNR Institute of Cell Biology and Neurobiology, Monterotondo 00015, Italy
| | - Gabriella Tognola
- CNR Institute of Electronics, Computer and Telecommunication Engineering, 20133 Milano, Italy
| | - Giulia Gentile
- CNR Institute of Neurological Sciences, 95126 Catania, Italy
| | | | - Denis Cuccaro
- CNR Institute of Neurological Sciences, 95126 Catania, Italy
| | | | | | - Guy Van Camp
- Center of Medical Genetics, University of Antwerp and Antwerp University Hospital, Universiteitsplein 1, 2610 Antwerp, Belgium
| | - Erik Fransen
- Department of Biomedical Sciences, University of Antwerp, 2650 Antwerp, Belgium
| | - Marco Brumat
- Dept Med Surg & Hlth Sci, University of Trieste, Trieste, Italy; IRCCS Burlo Garofolo, Inst Maternal & Child Hlth, Trieste, Italy
| | - Giorgia Girotto
- Dept Med Surg & Hlth Sci, University of Trieste, Trieste, Italy; IRCCS Burlo Garofolo, Inst Maternal & Child Hlth, Trieste, Italy
| | - Gaetano Paludetti
- Università Cattolica del Sacro Cuore, Largo F. Vito 1, 00168 Rome, Italy; Institute of Otolaryngology, Fondazione Policlinico Universitario A. Gemelli IRCCS, Largo F. Vito 1, 00168 Rome, Italy
| | - Paolo Gasparini
- Dept Med Surg & Hlth Sci, University of Trieste, Trieste, Italy; IRCCS Burlo Garofolo, Inst Maternal & Child Hlth, Trieste, Italy.
| | | | - Fabio Mammano
- CNR Institute of Cell Biology and Neurobiology, Monterotondo 00015, Italy; University of Padova, Department of Physics and Astronomy "G. Galilei", Padova, Italy.
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Xiao H, Liu W, Zhao Z, Zhang Y, Song Y, Luo B. Single nucleotide polymorphism rs2274084 of gap junction protein beta 2 gene among Epstein-Barr virus-associated tumors. Cancer Biomark 2018; 21:499-504. [PMID: 29103018 DOI: 10.3233/cbm-170078] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
BACKGROUND Gap junction protein beta 2 gene (GJB2) encodes one of connexins- Connexin 26 (Cx26), which mainly expressed in epithelial cells. Cx26 is usually considered a channel to exchange information between cells, which plays a critical role in tumor cell proliferation. OBJECTIVE We investigated GJB2 rs2274084 polymorphism in three types of tumors, including nasophoryngeal carcinoma (NPC), gastric cancer (GC) and lymphoma. METHODS Proteinase K digestion and phenolchloroform purification and QIAamp DNA FFPE tissue kit was used for DNA extraction. The genotype of GJB2 gene rs2274084 was detected through Sequenom MassARRAY SNP technique. The Chi-square test and Fisher's exact test were used to compare the differences between two groups. RESULTS The genotype frequency of GJB2 gene rs2274084 was significantly different between EBV-positive NPC and normal control (P< 0.05). However, for EBV-associated gastric cancer (EBVaGC), EBV-negative gastric cancer (EBVnGC) and lymphoma, no significant differences were found in comparison with the normal control. CONCLUSIONS The mutation rate of TT genotype was a risk factor to the occurrence of EBV-positive NPC.
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Affiliation(s)
- Hua Xiao
- Department of Medical Microbiology, Qingdao University Medical College, Qingdao 266021, Shandong, China
| | - Wen Liu
- Department of Medical Microbiology, Qingdao University Medical College, Qingdao 266021, Shandong, China
| | - Zhenzhen Zhao
- Department of Medical Microbiology, Qingdao University Medical College, Qingdao 266021, Shandong, China
| | - Yan Zhang
- Department of Medical Microbiology, Qingdao University Medical College, Qingdao 266021, Shandong, China.,Department of Clinical Laboratory, Central Hospital of Zibo, Zibo 255036, Shandong, China
| | - Yingying Song
- Department of Medical Microbiology, Qingdao University Medical College, Qingdao 266021, Shandong, China
| | - Bing Luo
- Department of Medical Microbiology, Qingdao University Medical College, Qingdao 266021, Shandong, China
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Alizadeh H, Davoodi J, Rafii-Tabar H. Deconstruction of the human connexin 26 hemichannel due to an applied electric field; A molecular dynamics simulation study. J Mol Graph Model 2017; 73:108-114. [PMID: 28259639 DOI: 10.1016/j.jmgm.2017.02.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Revised: 02/12/2017] [Accepted: 02/13/2017] [Indexed: 10/20/2022]
Abstract
Connexins are a 21-member membrane protein family constituting channels evolved in direct communication between adjacent cells by passaging cytoplasmic molecules and ions. Hexametrical assembly of connexin proteins in plasma membrane forms a wide aqueous pore known as connexin hemichannel. These hemichannels mediate cytoplasm and extracellular milieu communication both in many external tissues and in the central nervous system. In this study, a series of molecular dynamics simulations has been performed to investigate the effect of applied static and alternating electric fields on the stability and conformation of human connexin26 hemichannel. The root mean square deviations of C-alpha atoms, the dipole moment distribution, the number of inter-protein hydrogen bonds and the number of water-protein hydrogen bonds were used to assess connexin26 hemichannel stability. In the static field case, our results show that although the lowest field used in this study (0.1V/nm) does not lead to the hemichannel deconstruction, stronger fields (>0.1V/nm), however, disrupt the protein structure during the simulations time period. Furthermore, in the alternating case, compared to static field case, field effects on the connexin26 hemichannel conformation are reduced and consequently the protein maintains its native structure for longer times. Specifically, for the highest frequency used in this study (50GHz), the hemichannel keeps its structure even under the effect of the strongest field (0.4V/nm). According to our results, the protein secondary structure is preserved in the characteristic times determined for the protein deconstruction. Consequently, we suggest that the protein deconstruction is due to the tertiary and quaternary structure loss.
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Affiliation(s)
- Hadi Alizadeh
- Department of Physics, Faculty of Sciences, University of Zanjan, Zanajn, Iran
| | - Jamal Davoodi
- Department of Physics, Faculty of Sciences, University of Zanjan, Zanajn, Iran
| | - Hashem Rafii-Tabar
- Department of Medical Physics and Biomedical Engineering, School of Medicine, Shahid Beheshti University of Medical Science, Tehran, Iran.
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Abstract
Gap junction beta 2 (GJB2) gene is the most commonly mutated connexin gene in patients with autosomal recessive and dominant hearing loss. According to Ensembl (release 74) database, 1347 sequence variations are reported in the GJB2 gene and about 13.5% of them are categorized as missense SNPs or nonsynonymous variant. Because of the high incidence of GJB2 mutations in hearing loss patients, revealing the molecular effect of GJB2 mutations on protein structure may also provide clear point of view regarding the molecular etiology of deafness. Hence, the aim of this study is to analyze structural and functional consequences of all known GJB2 missense variations to the Cx26 protein by applying multiple bioinformatics methods. Two-hundred and eleven nonsynonymous variants were collected from Ensembl release 74, Leiden Open Variation Database (LOVD) and The Human Gene Mutation Database (HGMD). A number of bioinformatic tools were utilized for predicting the effect of GJB2 missense mutations at the sequence, structural, and functional levels. Some of the mutations were found to locate highly conserved regions and have structural and functional properties. Moreover, GJB2 mutations were also found to affect Cx26 protein at the molecular level via loss or gain of disorder, catalytic site, and post-translational modifications, including methylation, glycosylation, and ubiquitination. Findings, presented here, demonstrated the application of bioinformatic algorithms to predict the effects of mutations causing hearing impairment. I expect, this type of analysis will serve as a start point for future experimental evaluation of the GJB2 gene mutations and it will also be helpful in evaluating other deafness-related gene mutations.
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Rodriguez-Paris J, Waldhaus J, Gordhandas JA, Pique L, Schrijver I. Comparative functional characterization of novel non-syndromic GJB2 gene variant p.Gly45Arg and lethal syndromic variant p.Gly45Glu. PeerJ 2016; 4:e2494. [PMID: 27761313 PMCID: PMC5068369 DOI: 10.7717/peerj.2494] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Accepted: 08/26/2016] [Indexed: 11/20/2022] Open
Abstract
We characterized a novel GJB2 missense variant, c.133G>A, p.Gly45Arg, and compared it with the only other variant at the same amino acid position of the connexin 26 protein (Cx26) reported to date: c.134G>A, p.Gly45Glu. Whereas both variants are associated with hearing loss and are dominantly inherited, p.Gly45Glu has been implicated in the rare fatal keratitis-ichthyosis-deafness (KID) syndrome, which results in cutaneous infections and septicemia with premature demise in the first year of life. In contrast, p.Gly45Arg appears to be non-syndromic. Subcellular localization experiments in transiently co-transfected HeLa cells demonstrated that Cx26-WT (wild-type) and p.Gly45Arg form gap junctions, whereas Cx26-WT with p.Gly45Glu protein does not. The substitution of a nonpolar amino acid glycine in wildtype Cx26 at position 45 with a negatively charged glutamic acid (acidic) has previously been shown to interfere with Ca2+ regulation of hemichannel gating and to inhibit the formation of gap junctions, resulting in cell death. The novel variant p.Gly45Arg, however, changes this glycine to a positively charged arginine (basic), resulting in the formation of dysfunctional gap junctions that selectively affect the permeation of negatively charged inositol 1,4,5-trisphosphate (IP3) and contribute to hearing loss. Cx26 p.Gly45Arg transfected cells, unlike cells transfected with p.Gly45Glu, thrived at physiologic Ca2+ concentrations, suggesting that Ca2+ regulation of hemichannel gating is unaffected in Cx26 p.Gly45Arg transfected cells. Thus, the two oppositely charged amino acids that replace the highly conserved uncharged glycine in p.Gly45Glu and p.Gly45Arg, respectively, produce strikingly different effects on the structure and function of the Cx26 protein.
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Affiliation(s)
- Juan Rodriguez-Paris
- Department of Pathology, Stanford University, Stanford, CA, United States of America
| | - Jörg Waldhaus
- Department of Otolaryngology, Head and Neck Surgery, Stanford University, Stanford, CA, United States of America
| | - Jeenal A Gordhandas
- Department of Pathology, Stanford University, Stanford, CA, United States of America
| | - Lynn Pique
- Department of Pathology, Stanford University, Stanford, CA, United States of America
| | - Iris Schrijver
- Department of Pathology, Stanford University, Stanford, CA, United States of America.,Department of Pediatrics, Stanford University, Stanford, CA, United States of America
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Sanecka A, Biernacka EK, Sosna M, Mueller-Malesinska M, Ploski R, Skarzynski H, Piotrowicz R. Evaluation of electrocardiographic parameters in patients with hearing loss genotyped for the connexin 26 gene (GJB2) mutations. Braz J Otorhinolaryngol 2016; 83:176-182. [PMID: 27177978 PMCID: PMC9442716 DOI: 10.1016/j.bjorl.2016.02.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2015] [Revised: 02/22/2016] [Accepted: 02/28/2016] [Indexed: 11/17/2022] Open
Abstract
Introduction Several studies have associated congenital sensorineural hearing loss in children with prolongation of the cardiac parameter QTc. The cause of this association is unknown. At the same time, mutations in GJB2, which encodes connexin 26, are the most common cause of congenital hearing impairment. Objective To compare electrocardiographic parameters (PR interval, QRS complex, and QTc interval) in patients with hearing loss who were tested for mutations in GJB2 and GJB6 to investigate whether these mutations affect electrical activity of the heart. Methods 346 patients (176 males, 170 females) with sensorineural hearing loss of 30 dB HL or more, aged 21.8 ± 19.9 years (including 147 children <14 years), underwent both genetic study for GJB2 and GJB6 mutations and electrocardiography. Results Mutations in GJB2, including homozygotes and heterozygotes, were found in 112 (32%) patients. There were no significant differences in ECG parameters between groups of patients with and without mutations in GJB2. No differences were observed either in men (mean PR with mutation: 155 ± 16.6 vs. 153.6 ± 30.1 without; QRS: 99.9 ± 9.9 vs. 101.1 ± 15.4; QTc: 414.9 ± 29.9 vs. 412.4 ± 25.7) or women (mean PR with: 148.7 ± 21 vs. 143.8 ± 22.8 without; QRS: 94.8 ± 7.6 vs. 92.9 ± 9.6; QTc: 416.8 ± 20.6 vs. 424.9 ± 22.8). In similar fashion, we did we find any significant differences between groups of children with and without GJB2 mutations (mean PR with: 126.3 ± 19.6 vs. 127 ± 19.7 without; QRS: 80.7 ± 9.5 vs. 79.4 ± 11.6; QTc: 419.7 ± 23.5 vs. 419.8 ± 24.8). Conclusion No association was found between the presence of GJB2 mutations encoding connexin 26 in patients with hearing loss and their ECG parameters (PR, QRS, QTc).
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Affiliation(s)
| | | | - Magdalena Sosna
- Institute of Physiology and Pathology of Hearing, World Hearing Center, Nadarzyn, Poland
| | | | - Rafal Ploski
- Medical University of Warsaw, Department of Medical Genetics, Warsaw, Poland
| | - Henryk Skarzynski
- Institute of Physiology and Pathology of Hearing, World Hearing Center, Nadarzyn, Poland.
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Dória M, Fernandes S, Moura CP. Study of Met34Thr variant in nonsyndromic hearing loss in four Portuguese families. Porto Biomed J 2016; 1:32-35. [PMID: 32258544 DOI: 10.1016/j.pbj.2015.07.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2015] [Accepted: 07/28/2015] [Indexed: 10/21/2022] Open
Abstract
Objective The purpose of this work was to characterize the Met34Thr variant in a group of patients with nonsyndromic hearing loss, in order to establish a genotype-phenotype correlation. Methods 13 cases from 4 unrelated Portuguese families were selected, in which one or more hearing-impaired members had Met34Thr variant. Results Met34Thr variant was identified in 11/13 cases. Two cases have an additional mutation - Val153Ile and 35delG. Hearing loss was mild in 2 patients (Met34Thr/Val153Ile; Met34Thr/Met34Thr), moderate in 3(Met34Thr/WT; Met34Thr/35delG; Met34Thr/Met34Thr), severe in 2 (2 Met34Thr/WT) and profound in 1 (Met34Thr/WT). Three individuals with Met34Thr had normal hearing thresholds. Conclusion The present data corroborate the hypothesis that the Met34Thr variant is associated with mild-to-severe forms of deafness and that this variant seems to segregate with a dominant hearing loss with incomplete penetrance and a variable expression of the phenotype. However, other factors are likely to also have a pathologic effect.
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Affiliation(s)
- Mariana Dória
- Faculty of Medicine, University of Porto, Porto, Portugal
| | - Susana Fernandes
- Department of Human Genetics, Faculty of Medicine, University of Porto/São João Hospital Center, Porto, Portugal.,Institute for Research and Innovation in Health/Instituto de Investigação e Inovação em Saúde, University of Porto, Porto, Portugal
| | - Carla Pinto Moura
- Faculty of Medicine, University of Porto, Porto, Portugal.,Institute for Research and Innovation in Health/Instituto de Investigação e Inovação em Saúde, University of Porto, Porto, Portugal.,Department of Otorhinolaryngology and Department of Human Genetics, São João Hospital Center, Porto, Portugal
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26
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Burke WF, Warnecke A, Schöner-Heinisch A, Lesinski-Schiedat A, Maier H, Lenarz T. Prevalence and audiological profiles of GJB2 mutations in a large collective of hearing impaired patients. Hear Res 2016; 333:77-86. [PMID: 26778469 DOI: 10.1016/j.heares.2016.01.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/18/2015] [Revised: 01/07/2016] [Accepted: 01/13/2016] [Indexed: 11/28/2022]
Abstract
Mutations in the GJB2 gene are known to represent the commonest cause of hereditary and congenital hearing loss. In this study, a complete sequencing of the GJB2 gene in a cohort of 506 patients from a single, large cochlear implant program in Europe was performed. Audiological testing for those patients who could actively participate was performed using pure tone audiometry (PTA). Those unable to undergo PTA were measured using click-auditory brainstem response (ABR). Data analysis was performed to determine genotype-phenotype correlations of the mutational status vs. audiological profiles and vs. age at the time of presentation. An overall prevalence of biallelic mutations of 13.4% was found for the total collective. When subsets of younger patients were examined, the prevalence increased to 27% of those up to age 18 and 35% of those up to age 5 at the time of testing, respectively. This increase was found to be highly significant (p < 0.001). Analysis of the mean PTA thresholds revealed a strong correlation between allele combination status and mean PTA (p = 0.021). The prevalence of simple heterozygotes was found to be approximately 10.1%, which is around 3.3 times the value expected in the general population. As GJB2 follows a recessive pattern of inheritance, the question arises as to why such a large fraction of simple heterozygotes was observed among the hearing impaired patients included in this study.
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Affiliation(s)
- W F Burke
- Department of Otolaryngology, Hannover Medical School, Hannover, Germany; Cluster of Excellence, Hearing4All, Germany.
| | - A Warnecke
- Department of Otolaryngology, Hannover Medical School, Hannover, Germany; Cluster of Excellence, Hearing4All, Germany
| | - A Schöner-Heinisch
- Institute for Human Genetics, Hannover Medical School, Hannover, Germany
| | | | - H Maier
- Department of Otolaryngology, Hannover Medical School, Hannover, Germany; Cluster of Excellence, Hearing4All, Germany
| | - T Lenarz
- Department of Otolaryngology, Hannover Medical School, Hannover, Germany; Cluster of Excellence, Hearing4All, Germany
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Lee MY, Takada T, Takada Y, Kappy MD, Beyer LA, Swiderski DL, Godin AL, Brewer S, King WM, Raphael Y. Mice with conditional deletion of Cx26 exhibit no vestibular phenotype despite secondary loss of Cx30 in the vestibular end organs. Hear Res 2015; 328:102-12. [PMID: 26232528 DOI: 10.1016/j.heares.2015.07.018] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/14/2015] [Revised: 07/22/2015] [Accepted: 07/23/2015] [Indexed: 01/19/2023]
Abstract
Connexins are components of gap junctions which facilitate transfer of small molecules between cells. One member of the connexin family, Connexin 26 (Cx26), is prevalent in gap junctions in sensory epithelia of the inner ear. Mutations of GJB2, the gene encoding Cx26, cause significant hearing loss in humans. The vestibular system, however, does not usually show significant functional deficits in humans with this mutation. Mouse models for loss of Cx26 function demonstrate hearing loss and cochlear pathology but the extent of vestibular dysfunction and organ pathology are less well characterized. To understand the vestibular effects of Cx26 mutations, we evaluated vestibular function and histology of the vestibular sensory epithelia in a conditional knockout (CKO) mouse with Cx26 loss of function. Transgenic C57BL/6 mice, in which cre-Sox10 drives excision of the Cx26 gene from non-sensory cells flanking the sensory epithelium of the inner ear (Gjb2-CKO), were compared to age-matched wild types. Animals were sacrificed at ages between 4 and 40 weeks and their cochlear and vestibular sensory organs harvested for histological examination. Cx26 immunoreactivity was prominent in the peripheral vestibular system and the cochlea of wild type mice, but absent in the Gjb2-CKO specimens. The hair cell population in the cochleae of the Gjb2-CKO mice was severely depleted but in the vestibular organs it was intact, despite absence of Cx26 expression. The vestibular organs appeared normal at the latest time point examined, 40 weeks. To determine whether compensation by another connexin explains survival of the normal vestibular sensory epithelium, we evaluated the presence of Cx30 in the Gjb2-CKO mouse. We found that Cx30 labeling was normal in the cochlea, but it was decreased or absent in the vestibular system. The vestibular phenotype of the mutants was not different from wild-types as determined by time on the rotarod, head stability tests and physiological responses to vestibular stimulation. Thus presence of Cx30 in the cochlea does not compensate for Cx26 loss, and the absence of both connexins from vestibular sensory epithelia is no more injurious than the absence of one of them. Further studies to uncover the physiological foundation for this difference between the cochlea and the vestibular organs may help in designing treatments for GJB2 mutations.
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Affiliation(s)
- Min Young Lee
- Kresge Hearing Research Institute, Department of Otolaryngology - Head and Neck Surgery, University of Michigan, 1150 West. Medical Center Dr., Ann Arbor, MI 48109-5648, USA
| | - Tomoko Takada
- Kresge Hearing Research Institute, Department of Otolaryngology - Head and Neck Surgery, University of Michigan, 1150 West. Medical Center Dr., Ann Arbor, MI 48109-5648, USA
| | - Yohei Takada
- Kresge Hearing Research Institute, Department of Otolaryngology - Head and Neck Surgery, University of Michigan, 1150 West. Medical Center Dr., Ann Arbor, MI 48109-5648, USA
| | - Michelle D Kappy
- Kresge Hearing Research Institute, Department of Otolaryngology - Head and Neck Surgery, University of Michigan, 1150 West. Medical Center Dr., Ann Arbor, MI 48109-5648, USA
| | - Lisa A Beyer
- Kresge Hearing Research Institute, Department of Otolaryngology - Head and Neck Surgery, University of Michigan, 1150 West. Medical Center Dr., Ann Arbor, MI 48109-5648, USA
| | - Donald L Swiderski
- Kresge Hearing Research Institute, Department of Otolaryngology - Head and Neck Surgery, University of Michigan, 1150 West. Medical Center Dr., Ann Arbor, MI 48109-5648, USA
| | - Ashley L Godin
- Kresge Hearing Research Institute, Department of Otolaryngology - Head and Neck Surgery, University of Michigan, 1150 West. Medical Center Dr., Ann Arbor, MI 48109-5648, USA
| | - Shannon Brewer
- Kresge Hearing Research Institute, Department of Otolaryngology - Head and Neck Surgery, University of Michigan, 1150 West. Medical Center Dr., Ann Arbor, MI 48109-5648, USA
| | - W Michael King
- Kresge Hearing Research Institute, Department of Otolaryngology - Head and Neck Surgery, University of Michigan, 1150 West. Medical Center Dr., Ann Arbor, MI 48109-5648, USA
| | - Yehoash Raphael
- Kresge Hearing Research Institute, Department of Otolaryngology - Head and Neck Surgery, University of Michigan, 1150 West. Medical Center Dr., Ann Arbor, MI 48109-5648, USA.
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Bosen F, Celli A, Crumrine D, vom Dorp K, Ebel P, Jastrow H, Dörmann P, Winterhager E, Mauro T, Willecke K. Altered epidermal lipid processing and calcium distribution in the KID syndrome mouse model Cx26S17F. FEBS Lett 2015; 589:1904-10. [PMID: 26070424 DOI: 10.1016/j.febslet.2015.05.047] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2015] [Revised: 05/15/2015] [Accepted: 05/18/2015] [Indexed: 12/23/2022]
Abstract
The keratitis-ichthyosis-deafness (KID) syndrome is caused by mutations in the gap junctional channel protein connexin 26 (Cx26), among them the mutation Cx26S17F. Heterozygous Cx26S17F mice resemble the human KID syndrome, i.e. exhibiting epidermal hyperplasia and hearing impairments. Newborn Cx26S17F mice show a defective epidermal water barrier as well as altered epidermal lipid secretion and location. Linoleoyl ω-esterified ceramides are strongly decreased on the skin surface of Cx26S17F mice. Moreover, the epidermal calcium gradient is altered in the mutant mice. These alterations may be caused by an abnormal Cx26S17F channel function that leads to a defective epidermal water barrier, which in turn may trigger the hyperproliferation seen in the KID syndrome.
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Affiliation(s)
- Felicitas Bosen
- LIMES (Life and Medical Science Institute), Molecular Genetics, University of Bonn, 53115 Bonn, Germany
| | - Anna Celli
- Department of Dermatology, SF-VAMC and UCSF, San Francisco, CA, USA
| | - Debra Crumrine
- Department of Dermatology, SF-VAMC and UCSF, San Francisco, CA, USA
| | - Katharina vom Dorp
- Institute of Molecular Physiology and Biotechnology of Plants, University of Bonn, Germany
| | - Philipp Ebel
- LIMES (Life and Medical Science Institute), Molecular Genetics, University of Bonn, 53115 Bonn, Germany
| | - Holger Jastrow
- Electron Microscopy Unit, Imaging Center Essen, University Clinic Essen, Germany
| | - Peter Dörmann
- Institute of Molecular Physiology and Biotechnology of Plants, University of Bonn, Germany
| | - Elke Winterhager
- Electron Microscopy Unit, Imaging Center Essen, University Clinic Essen, Germany
| | - Theodora Mauro
- Department of Dermatology, SF-VAMC and UCSF, San Francisco, CA, USA
| | - Klaus Willecke
- LIMES (Life and Medical Science Institute), Molecular Genetics, University of Bonn, 53115 Bonn, Germany.
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Keivani A, Haghighat-Nia A, Fazel-Najafabadi E, Hosseinzadeh M, Salehi M. A new compound heterozygous mutation in GJB2 causes nonsyndromic hearing loss in a consanguineous Iranian family. Int J Pediatr Otorhinolaryngol 2015; 79:553-6. [PMID: 25708704 DOI: 10.1016/j.ijporl.2015.01.027] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Revised: 01/20/2015] [Accepted: 01/22/2015] [Indexed: 11/17/2022]
Abstract
OBJECTIVE To investigate mutations in GJB2 in a consanguineous Iranian family with multiple members affected by non-syndromic hearing loss. METHODS DNA was extracted from blood samples and the coding region of the conexin 26 gene was amplified using PCR. Bidirectional sequencing was carried out on PCR products. RESULTS Direct sequencing of the PCR products led to the identification of a novel compound heterozygous mutation of c.551G>C/c.397T>G (p.R184P/p.W133G) and a previously reported homozygous mutation c.551G>C (R184P/R184P). Compound heterozygous mutation was identified in the father and his daughter and homozygous mutation was identified in his affected son. In silico analysis of p.W133G predicted mutation has deleterious effect on protein structure. CONCLUSION These results show the usefulness of GJB2 mutation screening and bioinformatic analysis for genetic diagnosis and counseling of non-syndromic hearing loss.
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Affiliation(s)
- Azadeh Keivani
- Medical Genetics Laboratory, Alzahra University Hospital, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Asieh Haghighat-Nia
- Medical Genetics Laboratory, Alzahra University Hospital, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Esmat Fazel-Najafabadi
- Medical Genetics Laboratory, Alzahra University Hospital, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Majid Hosseinzadeh
- Medical Genetics Laboratory, Alzahra University Hospital, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Mansoor Salehi
- Medical Genetics Laboratory, Alzahra University Hospital, Isfahan University of Medical Sciences, Isfahan, Iran; Division of Genetics and Molecular Biology, Medical School, Isfahan University of Medical Sciences, Isfahan, Iran.
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30
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Kuo CL. Etiopathogenesis of acquired cholesteatoma: prominent theories and recent advances in biomolecular research. Laryngoscope 2014; 125:234-40. [PMID: 25123251 DOI: 10.1002/lary.24890] [Citation(s) in RCA: 90] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Revised: 06/24/2014] [Accepted: 07/24/2014] [Indexed: 01/22/2023]
Abstract
OBJECTIVE To review recent biomolecular advances in etiopathogenesis of acquired cholesteatoma. DATA SOURCES MEDLINE via OVID (to March 2014) and PubMed (to March 2014). REVIEW METHODS All articles referring to etiopathogenesis of acquired cholesteatoma were identified in the above databases, from which 89 articles were included in this review. RESULTS The mechanisms underlying the etiopathogenesis of acquired cholesteatoma remain a subject of competing hypotheses. Four theories dominate the debate, including theories of invagination, immigration, squamous metaplasia, and basal cell hyperplasia. However, no single theory has been able to explain the clinical characteristics of all cholesteatoma types: uncoordinated hyperproliferation, invasion, migration, altered differentiation, aggressiveness, and recidivism. Modern technologies have prompted a number of researchers to seek explanations at the molecular level. First, cholesteatomas could be considered an example of uncontrolled cell growth, capable of altering the balance toward cellular hyperproliferation and enhancing the capacity for invasion and osteolysis. Second, the dysregulation of cell growth control involves internal genomic or epigenetic alterations and external stimuli, which induce excessive host immune response to inflammatory and infectious processes. This comprises several complex and dynamic pathophysiologic changes that involve extracellular and intracellular signal transduction cascades. CONCLUSIONS This article summarizes the existing theories and provides conceptual insights into the etiopathogenesis of acquired cholesteatoma, with the aim of stimulating continued efforts to develop a nonsurgical means of treating the disorder.
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Affiliation(s)
- Chin-Lung Kuo
- Department of Otolaryngology-Head and Neck Surgery, Taipei Veterans General Hospital; Department of Otolaryngology, National Yang-Ming University School of Medicine; Institute of Brain Science, National Yang-Ming University; Department of Otolaryngology, National Defense Medical Center, Taipei, Taiwan, R.O.C.; Department of Otolaryngology, Taoyuan Armed Forces General Hospital, Taoyuan, Taiwan, R.O.C
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Thatcher A, Le Prell C, Miller J, Green G. ACEMg supplementation ameliorates progressive Connexin 26 hearing loss in a child. Int J Pediatr Otorhinolaryngol 2014; 78:563-5. [PMID: 24439969 DOI: 10.1016/j.ijporl.2013.12.030] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/06/2013] [Revised: 12/18/2013] [Accepted: 12/19/2013] [Indexed: 11/28/2022]
Abstract
Mutations in the gene encoding Connexin 26 are the most common cause of genetic hearing loss. The hearing loss is typically stable but may be progressive. The reason for progression is unknown. Antioxidants have been associated with attenuation of hearing loss from other insults. One antioxidant regimen consists of beta-carotene (metabolized to vitamin A), vitamin C, vitamin E, and magnesium (ACEMg). We present a child with Connexin 26 related hearing loss who experienced progressive hearing loss over 7 years of observation. He was given ACEMg daily for 3 years, during which time his progressive hearing loss was ameliorated.
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Affiliation(s)
- Aaron Thatcher
- University of Michigan, Department of Otolaryngology, United States.
| | - Colleen Le Prell
- University of Florida, Department of Speech, Language, and Hearing Sciences, United States.
| | - Josef Miller
- University of Michigan, Department of Otolaryngology, United States.
| | - Glenn Green
- University of Michigan, Department of Otolaryngology, United States.
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Volo T, Sathiyaseelan T, Astolfi L, Guaran V, Trevisi P, Emanuelli E, Martini A. Hair phenotype in non-syndromic deafness. Int J Pediatr Otorhinolaryngol 2013; 77:1280-5. [PMID: 23751281 DOI: 10.1016/j.ijporl.2013.05.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/12/2013] [Revised: 05/08/2013] [Accepted: 05/09/2013] [Indexed: 10/26/2022]
Abstract
The GJB2 gene is located on chromosome 13q12 and it encodes the connexin 26, a transmembrane protein involved in cell-cell attachment of almost all tissues. GJB2 mutations cause autosomal recessive (DFNB1) and sometimes dominant (DFNA3) non-syndromic sensorineural hearing loss. Moreover, it has been demonstrated that connexins are involved in regulation of growth and differentiation of epidermal tissues. Hence, mutations in GJB2 gene, which is responsible for non-syndromic deafness, may be associated with an abnormal skin and hair phenotype. We analyzed hair samples from 96 subjects: a study group of 42 patients with hearing impairments of genetic origin (38 with a non-syndromic form, 4 with a syndromic form), and a control group including 54 people, i.e. 43 patients with other, non-genetic hearing impairments and 11 healthy volunteers aged up to 10 years old. The surface structure of 49 hair samples was normal, whereas in 45 cases it was altered, with a damaged appearance. Two hair samples were considered unclassifiable: one from the patient heterozygotic for the pendrin mutation (Fig. 2C), the other from a patient from Ghana with a R134W mutation (Fig. 2D). Among the 43 altered hair samples, 31 belonged to patients with connexin mutations and the other 12 came from patients without connexin mutations.
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Affiliation(s)
- T Volo
- Otolaryngology and Otosurgery Unit, University Hospital of Padova, Italy.
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Zhang Y, Hao H. Conserved glycine at position 45 of major cochlear connexins constitutes a vital component of the Ca²⁺ sensor for gating of gap junction hemichannels. Biochem Biophys Res Commun 2013; 436:424-9. [PMID: 23756814 DOI: 10.1016/j.bbrc.2013.05.118] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2013] [Accepted: 05/29/2013] [Indexed: 11/28/2022]
Abstract
Mutations in gap junction (GJ) family of proteins, especially in the connexin (Cx) 26, are responsible for causing severe congenital hearing loss in a significant portion of patients (30-50% in various ethnic groups). Substitution of glycine at the position 45 of Cx26 to glutamic acid (p.G45E mutation) causes the Keratitis-ichthyosis-deafness (KID) syndrome. Previous studies have suggested that this point mutation caused a gain-of-function defect. However, the molecular mechanism of KID syndrome remains unclear. Since glycine at this position is conserved in many Cxs expressed in the cochlea, we tested the hypothesis that glycine at position 45 is an important component of the sensor regulating the Ca(2+) gating of GJ hemichannels. Using reconstituted Cx30, 32 and 43 expressed in the HEK 293 cells, we compared the functions of wild type and p.G45E mutant Cxs. We found that G45E in Cx30 resulted in similar deleterious cellular effects as Cx26 did. Cell death occurred within 24h of transfection, which was rescued by increasing extracellular Ca(2+) concentration ([Ca(2+)]o). Dye loading assay showed that Cx30 G45E, similar to Cx26 G45E, had leaky hemichannels at physiological [Ca(2+)]o (1.2 mM). Higher [Ca(2+)]o reduced the dye loading in a dose-dependent manner. Whole cell membrane current recordings also indicated that G45E caused increased hemichannel activities. p.G45E mutations of Cx32 and 43 also resulted in leaky hemichannels compared to their respective wild types in lower [Ca(2+)]o. Our data in this study provided further support for the hypothesis that glycine at position 45 is a conserved Ca(2+) sensor for the gating of GJ hemichannels among multiple Cx subtypes expressed in the cochlea.
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Affiliation(s)
- Yanping Zhang
- Department of Otolaryngology, 309th Hospital of Chinese PLA, Road Heishanhu, Haidian District, Beijing 100091, China.
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Zhang Y, Zhang X, Li L, Sun Y, Sun J. Apoptosis Progression in the Hair Cells in the Organ of Corti of GJB2 Conditional Knockout Mice. Clin Exp Otorhinolaryngol 2012; 5:132-8. [PMID: 22977709 DOI: 10.3342/ceo.2012.5.3.132] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2011] [Revised: 12/01/2011] [Accepted: 01/03/2012] [Indexed: 12/05/2022] Open
Abstract
Objectives Apoptosis may play an important role in the mechanism underlying the GJB2 gene conditional knockout (cCx26) mice cochlear cell death. The objective of this study was to explore the the damage mode of the outer hair cells (OHCs) and its real time point of apoptosis and provide information to further explore the role of apoptosis in the happening of hearing loss in cCx26 mice. Methods Cochleae from mice at various developmental stages (P8, P12, and P21) were dissected out and first used to be observed under the scanning electron microscope (SEM). Basilar membranes from mice at P8, P14, P18, and P21 were stained by fluorescein isothiocyanate-conjugated phalloidin and propidium iodide (PI) and examined under confocal microscope. Results The loss of OHCs of cCx26 knockout mice was first set between P12 and P21 under SEM. Whole mount phalloidin and PI staining revealed that obvious apoptotic appearance of the OHCs surface morphology was observed at P18. Conclusion Typical apoptotic morphology was found in the OHCs in the organ of Corti of the cCx26 mice at P18. This may provide information to further study the role of apoptosis in the occurrence of hearing loss of cCx26 mice.
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Shin JW, Lee SC, Lee HK, Park HJ. Genetic Screening of GJB2 and SLC26A4 in Korean Cochlear Implantees: Experience of Soree Ear Clinic. Clin Exp Otorhinolaryngol 2012; 5 Suppl 1:S10-3. [PMID: 22701767 DOI: 10.3342/ceo.2012.5.S1.S10] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2011] [Revised: 01/04/2012] [Accepted: 02/02/2012] [Indexed: 11/18/2022] Open
Abstract
Objectives Genetic hearing loss is highly heterogeneous and more than 100 genes are predicted to cause this disorder in humans. In spite of this large genetic heterogeneity, mutations in SLC26A4 and GJB2 genes are primarily responsible for the major etiologies of genetic hearing loss among Koreans. The purpose of this study is to investigate the genetic cause of deafness in Korean cochlear implantees by performing a genetic screening of the SLC26A4 and GJB2 genes. Methods The study cohort included 421 unrelated Korean patients with sensorineural hearing loss (SNHL) and who had received cochlear implants (CI) at Soree Ear Clinic from July 2002 to December 2010. Among 421 CI patients, we studied 230 cases who had received the genetic screening for SLC26A4 or GJB2 genes. Written informed consent was obtained from all participants. All patients had severe to profound, bilateral hearing loss. For 56 patients who showed enlarged vestibular aqueduct on their computed tomography (CT) scan, we analyzed SLC26A4. For 174 CT negative patients, GJB2 gene was sequenced. Results For the 56 SLC26A4 patients, 32 (57.1%) had two pathogenic recessive mutations in SLC26A4. A single recessive SLC26A4 mutation was identified in 14 patients (25%). H723R and IVS7-2A>G were the most commonly found mutations, accounting for 60.3% (47/78) and 30.8% (24/78) of the mutated alleles, respectively. For the 174 GJB2 patients, 20 patients (11.5%) had two pathogenic recessive mutations in GJB2. 235delC was the most common mutation, accounting for 43.0% (31/72) of mutant alleles. Conclusion The two major genes, SLC26A4 and GJB2, contribute major causes of deafness in CI patients. Continuous studies are needed to identify new genes that can cause hearing loss to Korean CI patients.
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Galehdari H, Foroughmand AM, Soorki MN, Mohammadian G. Absence of mutations in GJB2 (Connexin-26) gene in an ethnic group of southwest Iran. Indian J Hum Genet 2011; 15:9-12. [PMID: 20407643 PMCID: PMC2846572 DOI: 10.4103/0971-6866.50863] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND: The common GJB2 gene mutation (35delG) has been previously reported from Iranian patients that were affected with nonsyndromic autosomal recessive deafness. We, therefore, for the first time, investigated the prevalence and frequency of the GJB2 gene mutation in the Iranian deaf population with Arabian origins. MATERIALS AND METHODs: We amplified and sequenced the entire coding sequence of the GJB2 gene from 61 deaf patients and 26 control subjects. RESULT: None of the analyzed samples revealed deafness-associated mutation. CONCLUSION: This finding differs from several reports from Iran as we have focused on the GJB2 gene that possesses various mutations as the cause of congenital recessive deafness.
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Affiliation(s)
- Hamid Galehdari
- Department of Genetics, Faculty of Science, Chamran University, Ahwaz, Iran
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Lee JY, In SI, Kim HJ, Jeong SY, Choung YH, Kim YC. Hereditary palmoplantar keratoderma and deafness resulting from genetic mutation of Connexin 26. J Korean Med Sci 2010; 25:1539-42. [PMID: 20890442 PMCID: PMC2946671 DOI: 10.3346/jkms.2010.25.10.1539] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/15/2009] [Accepted: 12/17/2009] [Indexed: 11/24/2022] Open
Abstract
Gap junctions, which mediate rapid intercellular communication, consist of connexins, small transmembrane proteins that belong to a large family of proteins found throughout the species. Mutations in the GJB2 gene, encoding Connexin 26, can cause nonsyndromic autosomal recessive or dominant hearing loss with or without skin manifestations. A 3-yr-old Korean female and her mother presented to our clinic with diffuse hyperkeratosis of the palms and soles (May 3, 2007). Skin biopsies from the soles of both patients demonstrated histopathological evidence of palmoplantar keratoderma. The patient and a number of her maternal family members also had congenital hearing loss. The combination of congenital hearing loss and palmoplantar keratoderma, inherited as an autosomal dominant trait, led us to test for a mutation in the GJB2 gene in both patients. The results showed the R75W mutation of the GJB2 gene in both. In conclusion, the simultaneous occurrence of a GJB2 mutation in a mother and daughter suggests that R75W mutation cause autosomal dominant hearing loss presenting with palmoplantar keratoderma. To the best of our knowledge, this is the first report of a GJB2 mutation associated with syndromic autosomal dominant hearing loss and palmoplantar keratoderma in a Korean family.
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Affiliation(s)
- Jae Yeol Lee
- Department of Dermatology, Ajou University School of Medicine, Suwon, Korea
| | - Sung-Il In
- Department of Dermatology, Ajou University School of Medicine, Suwon, Korea
| | - Hyon J Kim
- Department of Genetics, Ajou University School of Medicine, Suwon, Korea
| | - Seon-Yong Jeong
- Department of Genetics, Ajou University School of Medicine, Suwon, Korea
| | - Yun Hoon Choung
- Department of Otolaryngology, Ajou University School of Medicine, Suwon, Korea
| | - You Chan Kim
- Department of Dermatology, Ajou University School of Medicine, Suwon, Korea
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