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Vallian Broojeni J, Kazemi A, Rezaei H, Vallian S. Exome sequencing identifies novel variants associated with non-syndromic hearing loss in the Iranian population. PLoS One 2023; 18:e0289247. [PMID: 37561809 PMCID: PMC10414579 DOI: 10.1371/journal.pone.0289247] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2022] [Accepted: 07/13/2023] [Indexed: 08/12/2023] Open
Abstract
Autosomal recessive non-syndromic hearing loss (ARNSHL) is a public health concern in the Iranian population, with an incidence of 1 in 166 live births. In the present study, the whole exome sequencing (WES) method was applied to identify the mutation spectrum of NSHL patients negative for GJB2 gene mutations. First, using ARMS PCR followed by Sanger sequencing of the GJB2 gene, 63.15% of mutations in patients with NSHL were identified. Among the identified mutations in GJB2:p.Val43Met and p.Gly21Arg were novel. The remaining patients were subjected to WES, which identified novel mutations including MYO15A:p.Gly39LeufsTer188, ADGRV1:p.Ser5918ValfsTer23, MYO7A: c.5856+2T>c (splicing mutation), FGF3:p.Ser156Cys. The present study emphasized the application of WES as an effective method for molecular diagnosis of NSHL patients negative for GJB2 gene mutations in the Iranian population.
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Affiliation(s)
- Jalal Vallian Broojeni
- Department of Cell and Molecular Biology& Microbiology, Faculty of Science and Technology, University of Isfahan, Isfahan, IR, Iran
| | - Arezu Kazemi
- Department of Cell and Molecular Biology& Microbiology, Faculty of Science and Technology, University of Isfahan, Isfahan, IR, Iran
| | - Halimeh Rezaei
- Department of Cell and Molecular Biology& Microbiology, Faculty of Science and Technology, University of Isfahan, Isfahan, IR, Iran
| | - Sadeq Vallian
- Department of Cell and Molecular Biology& Microbiology, Faculty of Science and Technology, University of Isfahan, Isfahan, IR, 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] [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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Abbaspour Rodbaneh E, Panahi M, Rahimi B, Mokabber H, Farajollahi R, Davarnia B. GJB2 mutations in Iranian Azeri population with autosomal recessive nonsyndromic hearing loss (ARNSHL): First report of c.238 C>A mutation in Iran. J Clin Lab Anal 2021; 35:e24024. [PMID: 34581455 PMCID: PMC8605150 DOI: 10.1002/jcla.24024] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Revised: 09/09/2021] [Accepted: 09/14/2021] [Indexed: 12/18/2022] Open
Abstract
Objective Autosomal‐recessive nonsyndromic hearing loss (ARNSHL) is a heterogeneous genetic disorder. Mutations in the gap junction protein beta 2 (GJB2) gene, encoding connexin 26, are a significant cause of ARNSHL in different ethnic groups. This study aimed to identify the frequency and type of GJB2 mutations in the Iranian Azeri population. Methods Fifty unrelated families presenting ARNSHL in Ardabil Province, the northwest of Iran, were studied to determine the frequency and type of GJB2 mutations leading to ARNSHL. ARMS‐PCR screened all DNA samples to detect c.35delG; p. Gly12Val mutation. In addition, normal samples for c.35delG; p. Gly12Val were analyzed by direct sequencing for other GJB2 mutations. Result Of the fifty families, 13 (26%) showed a GJB2 gene mutation, with c.35delG; p. Gly12Val mutation was the most prevalent one that occurred in eight (61.5%) out of the 13 families. Of the families, two were homozygous for c.358‐360delGAC; p. Glu120del mutation, and one was homozygous for c.290dupA; p. Tyr97Ter and c.299–300delAT; p. His100Arg mutations. Also, we detected a novel mutation, c.238C>A; p. Gln80lys, in one of the families. Conclusion Our findings are comparable to previous studies, indicating c.35d3lG; p. Gly12Val mutation in the GJB2 gene is the most common cause of GJB2‐related hearing loss in the Iranian Azeri population. Furthermore, our study highlights the significance of ARNSHL screening programs of live births based on local population data in Iran.
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Affiliation(s)
| | - Mohammad Panahi
- Department of Medical Biotechnology, Faculty of Advanced Medical Sciences, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Bahareh Rahimi
- Department of Medical Biotechnology, Faculty of Allied Medical Sciences, Iran University of Medical Sciences, Tehran, Iran
| | - Haleh Mokabber
- Medical Genetics and Pathology, Ardabil University of Medical Sciences, Ardabil, Iran
| | - Reza Farajollahi
- Medical Genetics and Pathology, Ardabil University of Medical Sciences, Ardabil, Iran.,Ardabil Welfare Organization, Ardabil, Iran
| | - Behzad Davarnia
- Medical Genetics and Pathology, Ardabil University of Medical Sciences, Ardabil, Iran
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Küçük Kurtulgan H, Altuntaş EE, Yıldırım ME, Özdemir Ö, Bağcı B, Sezgin İ. The Analysis of GJB2, GJB3, and GJB6 Gene Mutations in Patients with Hereditary Non-Syndromic Hearing Loss Living in Sivas. J Int Adv Otol 2020; 15:373-378. [PMID: 31846914 DOI: 10.5152/iao.2019.5401] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
OBJECTIVES The aim of the present study was to investigate the presence of GJB2, GJB3, and GJB6 gene mutations in non-syndromic sensorineural hearing loss (NSHL) cases living in Sivas region, to provide appropriate genetic counseling for cases who were found to have mutation, and to contribute to decrease the frequency of mutant allele in the next generation and plan treatment and rehabilitation with early diagnosis. MATERIALS AND METHODS The study included 53 unrelated cases that were diagnosed with congenital NSHL between June 2009 and March 2010. Multiplex ligation-dependent probe amplification method was used for genotyping of GJB2, GJB3, and GJB6 gene mutations. RESULTS Heterozygous 35delG variant was determined in 1.9% (n=1) of cases, homozygous 35delG in 15.1% (n=8), heterozygous IVS1+1G>A mutation in 1.9% (n=1), compound heterozygous in 3.8% (n=2), and homozygous IVS1+1G>A variant in 3.8% (n=2). None of the cases had mutation in GJB3 and GJB6 genes. Mutated allele frequencies in the present study were found to be 17.9% for 35delG and 6.6% for IVS1+1G>A. CONCLUSION The present study showed that 35delG mutation is the most common variant in the Sivas region, and that IVS1+1G>A mutation should be investigated in hearing loss. Another result of the present study was that genetic analyzes would allow early diagnosis of hearing impairments particularly when infants whose parents have consanguinity do not pass the newborn hearing screening.
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Affiliation(s)
- Hande Küçük Kurtulgan
- Department of Medical Genetics, Cumhuriyet University School of Medicine, Sivas, Turkey
| | | | - Malik Ejder Yıldırım
- Department of Medical Genetics, Cumhuriyet University School of Medicine, Sivas, Turkey
| | - Öztürk Özdemir
- Department of Medical Genetics, Çanakkale 18 Mart University, Çanakkale, Turkey
| | - Binnur Bağcı
- Department of Nutrition and Dietetics, Cumhuriyet University School of Medicine, Sivas, Turkey
| | - İlhan Sezgin
- Department of Medical Genetics, Cumhuriyet University School of Medicine, Sivas, Turkey
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Koohiyan M, Koohian F, Azadegan-Dehkordi F. GJB2-related hearing loss in central Iran: Review of the spectrum and frequency of gene mutations. Ann Hum Genet 2019; 84:107-113. [PMID: 31512227 DOI: 10.1111/ahg.12354] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Revised: 08/15/2019] [Accepted: 08/27/2019] [Indexed: 12/13/2022]
Abstract
Mutations in the GJB2 gene are a main cause of autosomal-recessive nonsyndromic hearing loss (ARNSHL) in many populations. Previous studies have estimated the average frequency of GJB2 mutations to be ∼16% in Iran, but would vary among different ethnic groups. Here, we have taken together and reviewed results from our two previous publications and data from searching other published mutation reports to provide a comprehensive collection of data for GJB2 mutations and HL in central Iran. In all, 332 unrelated families were included and analyzed for the prevalence and type of the GJB2 gene mutations. In total, the frequency of GJB2 mutations was found to be 16% in the central provinces, which is significantly higher than those identified in southern populations of Iran. Also, c.35delG was the most frequent mutation in the related population. The present study suggests that mutations in the GJB2 gene, especially c.35delG, are important causes of HL in central Iran and can be used as a basis of genetic counseling and clinical guidelines in this region.
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Affiliation(s)
- Mahbobeh Koohiyan
- Cancer Research Center, Shahrekord University of Medical Sciences, Shahrekord, Iran
| | - Farideh Koohian
- Department of Medical Physics, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran
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Koohiyan M. Genetics of Hereditary Hearing Loss in the Middle East: A Systematic Review of the Carrier Frequency of the GJB2 Mutation (35delG). Audiol Neurootol 2019; 24:161-165. [PMID: 31487726 DOI: 10.1159/000502201] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Accepted: 07/17/2019] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND AND OBJECTIVES Mutations in the GJB2 gene are a major cause of hearing loss in many populations. A single mutation of this gene (c.35delG) accounts for approximately 70% of mutations in Caucasians with a carrier frequency of 2-4% in Europe. This study aims to determine the rate of c.35delG carrier frequency in the Middle East. METHOD A systematic literature review of the PubMed, Google Scholar, Web of Science, and Science Direct databases was conducted for articles published before March 2019. The primary data of eligible studies including the number of samples, carrier frequency and so on were extracted. RESULTS Fourteen studies that involved 5,200 random controls from 15 populations of the Middle East were included and analyzed for the carrier frequency. The overall c.35delG carrier frequency was found to be 1.38% in the studied populations which is significantly lower than that identified in European populations, and also a west-to-east Middle Eastern gradient in the carrier frequency of c.35delG is suggested. CONCLUSION This study shows the importance of establishing prevalence, based on the local population, for screening and diagnostic programs of live births.
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Affiliation(s)
- Mahbobeh Koohiyan
- Cancer Research Center, Shahrekord University of Medical Sciences, Shahrekord, Iran,
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Koohiyan M, Azadegan-Dehkordi F, Koohian F, Hashemzadeh-Chaleshtori M. Genetics of Hearing Loss in North Iran Population: An Update of Spectrum and Frequency of GJB2 Mutations. J Audiol Otol 2019; 23:175-180. [PMID: 31569309 PMCID: PMC6773957 DOI: 10.7874/jao.2019.00059] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2019] [Accepted: 06/27/2019] [Indexed: 11/22/2022] Open
Abstract
Diagnosis of pre-lingual hearing loss (HL) is difficult owing to the high number of genes responsible. The most frequent cause of HL is DFNB1 due to mutations in the GJB2 gene. It represents up to 40% of HL cases in some populations. In Iran, it has previously been shown that DFNB1 accounts for 16-18% of cases but varies among different ethnic groups. Here, we reviewed results from our three previous publications and data from other published mutation reports to provide a comprehensive collection of data for GJB2 mutations and HL in northern Iran. In total, 903 unrelated families from six different provinces, viz., Gilan, Mazandaran, Golestan, Ghazvin, Semnan, and Tehran, were included and analyzed for the type and prevalence of GJB2 mutations. A total of 23 different genetic variants were detected from which 18 GJB2 mutations were identified. GJB2 mutations were 20.7% in the studied northern provinces, which was significantly higher than that reported in southern populations of Iran. Moreover, a gradient in the frequency of GJB2 mutations from north to south Iran was observed. c.35delG was the most common mutation, accounting for 58.4% of the cases studied. This study suggests that c.35delG mutation in GJB2 is the most important cause of HL in northern Iran.
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Affiliation(s)
- Mahbobeh Koohiyan
- Cancer Research Center, Basic Health Sciences Institute, Shahrekord University of Medical Sciences, Shahrekord, Iran
| | - Fatemeh Azadegan-Dehkordi
- Cellular and Molecular Research Center, Basic Health Sciences Institute, Shahrekord University of Medical Sciences, Shahrekord, Iran
| | - Farideh Koohian
- Department of Medical Physics, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Morteza Hashemzadeh-Chaleshtori
- Cellular and Molecular Research Center, Basic Health Sciences Institute, Shahrekord University of Medical Sciences, Shahrekord, Iran
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Jiang H, Niu Y, Qu L, Huang X, Zhu X, Tang G. A novel compound heterozygous mutation in the GJB2 gene is associated with non-syndromic hearing loss in a Chinese family. Biosci Trends 2019; 12:470-475. [PMID: 30473554 DOI: 10.5582/bst.2018.01156] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Autosomal recessive (AR) non-syndromic hearing loss (NSHL) is the most common form of hereditary deafness. Mutations in the gap junction protein beta 2 (GJB2) gene encoding connexin 26 (Cx26) account for about 50% of cases of ARNSHL. In the current study, a combination of exome sequencing and Sanger sequencing in a Chinese Dong family with ARNSHL allowed identification of a novel compound heterozygous mutation c.240G>C(p. Q80H)/C.109G>A(p.V37I) in exon 2 of the GJB2 gene, which co-segregated with the disease phenotype in this family and was not evident in 100 healthy controls. Bioinformatic analysis revealed that the two mutations in the GJB2 gene were probably pathogenic. Results indicated that the compound heterozygous variants, p.Q80H and p.V37I, in the GJB2 gene are associated with ARNSHL. The Q80H variant was initially identified in patients of Dong Chinese origin with NSHL. The current results broaden the spectrum of GJB2 mutations responsible for NSHL and have important implications for molecular diagnosis, treatment, and genetic counseling for this family.
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Affiliation(s)
- Haiou Jiang
- Department of Cellular Biology and Genetics, Hunan Provincial Key Laboratory of Dong Medicine, Hunan University of Medicine
| | - Youya Niu
- Department of Cellular Biology and Genetics, Hunan Provincial Key Laboratory of Dong Medicine, Hunan University of Medicine
| | - Lingfeng Qu
- Department of Cellular Biology and Genetics, Hunan Provincial Key Laboratory of Dong Medicine, Hunan University of Medicine
| | - Xueshuang Huang
- Department of Cellular Biology and Genetics, Hunan Provincial Key Laboratory of Dong Medicine, Hunan University of Medicine
| | - Xinlong Zhu
- Department of Cellular Biology and Genetics, Hunan Provincial Key Laboratory of Dong Medicine, Hunan University of Medicine
| | - Genyun Tang
- Department of Cellular Biology and Genetics, Hunan Provincial Key Laboratory of Dong Medicine, Hunan University of Medicine
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9
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Koohiyan M, Ahmadi A, Koohian F, Aghaei S, Amiri B, Hashemzadeh-Chaleshtori M. An update of spectrum and frequency of GJB2 mutations causing hearing loss in the south of Iran: A literature review. Int J Pediatr Otorhinolaryngol 2019; 119:136-140. [PMID: 30708180 DOI: 10.1016/j.ijporl.2019.01.036] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Revised: 01/21/2019] [Accepted: 01/23/2019] [Indexed: 11/18/2022]
Abstract
OBJECTIVE Mutations in the GJB2 gene are a major cause of autosomal recessive non-syndromic HL (ARNSHL) in many populations. Previous studies have estimated the average frequency of GJB2 mutations to be between 16 and 18% in Iran, but would vary among different ethnic groups. Here, we have taken together and reviewed results from our three previous publications and data from search other published mutation reports to provide a comprehensive collection of data for GJB2 mutations and HL in the south of Iran. METHODS In all, 447 unrelated families were included and analyzed for the prevalence and type of the GJB2 gene mutations. RESULTS Totally, the frequency of GJB2 mutations was found to be 11.5% in the southern provinces studied which is significantly lower than that identified in Northern populations of Iran, and also a southwest to southeast Iranian gradient in the frequency of GJB2 mutations is suggested. CONCLUSIONS This study highlights the importance of establishing prevalence, based on the local population for screening and diagnostic programs of live births in Iran.
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Affiliation(s)
- Mahbobeh Koohiyan
- Cancer Research Center, Shahrekord University of Medical Sciences, Shahrekord, Iran
| | - Amirhossein Ahmadi
- Pharmaceutical Sciences Research Center, Faculty of Pharmacy, Mazandaran University of Medical Sciences, Sari, Iran
| | - Farideh Koohian
- Department of Medical Physics, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Shahrzad Aghaei
- Department of Molecular Medicine, School of Advanced Technologies, Shahrekord of Medical Sciences, Shahrekord, Iran
| | - Beheshteh Amiri
- Cellular and Molecular Research Center, Basic Health Sciences Institute, Shahrekord University of Medical Sciences, Shahrekord, Iran
| | - Morteza Hashemzadeh-Chaleshtori
- Cellular and Molecular Research Center, Basic Health Sciences Institute, Shahrekord University of Medical Sciences, Shahrekord, Iran.
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Gibriel AA, Abou-Elew MH, Masmoudi S. Analysis of p.Gly12Valfs*2, p.Trp24* and p.Trp77Arg mutations in GJB2 and p.Arg81Gln variant in LRTOMT among non syndromic hearing loss Egyptian patients: implications for genetic diagnosis. Mol Biol Rep 2019; 46:2139-2145. [PMID: 30730013 DOI: 10.1007/s11033-019-04667-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Accepted: 01/30/2019] [Indexed: 11/28/2022]
Abstract
Hearing loss (HL) is a global sensory disorder that affects children and deprives them from their rights to enjoy standard social and educational levels. Although hundreds of genetic mutations across several genes have been linked to HL, very limited studies are available on Egyptian population which has high rate of consanguinity and HL. The frequency of the p.Gly12Valfs*2, p.Trp24* and p.Trp77Arg mutations in GJB2 along with the p.Arg81Gln variant in LRTOMT gene was investigated in Egyptian patients. 103 non-syndromic HL (NSHL) Egyptian patients and 100 control subjects were recruited in this study. PCR-RFLP and Direct sequencing were performed to screen and confirm presence/absence of those mutations in Egyptian population. The p.Gly12Valfs*2 mutation was found in eight patients (7.8%) (six homozygous and two heterozygous) with an allele frequency of 6.8%. The p.Trp24* and p.Trp77Arg were absent in both HL patients and controls. Another one patient had the heterozygous variant for p.Arg81Gln in LRTOMT gene. This study reports, for the first time, the presence of a heterozygous change for the p.Arg81Gln in LRTOMT gene in one Egyptian patient. The p.Gly12Valfs*2 mutation, but not the p.Trp24* nor the p.Trp77Arg, in GJB2 is the most frequent variant among Egyptian patients and would therefore be recommended for genetic counseling and diagnosis.
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Affiliation(s)
- Abdullah A Gibriel
- Biochemistry and Molecular Biology Department, Faculty of Pharmacy, The British University in Egypt (BUE), P.O. Box 259, 11728, Cairo, Egypt.
| | - Maha H Abou-Elew
- Otorhinolaryngology Department, Audio-Vestibular Unit, Faculty of Medicine, Kasr Al-Aini El-Manial University Hospital, Cairo University, Giza, Egypt
| | - Saber Masmoudi
- Laboboratoire Procédés de Criblage Moléculaire et Cellulaire, Centre de Biotechnologie de Sfax, Université de Sfax, Sfax, Tunisia
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GJB2 mutations causing autosomal recessive non-syndromic hearing loss (ARNSHL) in two Iranian populations: Report of two novel variants. Int J Pediatr Otorhinolaryngol 2018; 107:121-126. [PMID: 29501291 DOI: 10.1016/j.ijporl.2018.01.012] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/28/2017] [Revised: 01/14/2018] [Accepted: 01/15/2018] [Indexed: 11/21/2022]
Abstract
OBJECTIVE Hereditary hearing loss (HL) is a noticeable concern in medicine all over the world. On average, 1 in 166 babies born are diagnosed with HL in Iran, which makes it a major public health issue. Autosomal recessive non-syndromic HL (ARNSHL) is the most prevalent form of HL. Although over 60 genes have been identified for ARNSHL, GJB2 mutations are the most prevalent causes of ARNSHL in many populations. Previous studies have estimated the average frequency of GJB2 mutations to be between 16 and 18% in Iran, but would vary among different ethnic groups. In the present study, we aimed to determine the frequency and mutation profile of 70 deaf patients from two different provinces (center and west) of Iran. METHODS We enrolled 70 Iranian deaf patients with ARNSHL from Isfahan (40 family) and Hamedan (30 family) provinces. After extraction of genomic DNA, the entire coding region of GJB2 was directly sequenced in all patients. Multiplex PCR was used for detection of del(GJB6-D13S1830) and del(GJB6-D13S1854) in the GJB6 gene. In silico analyses were also performed by available software tools. RESULTS A total of eleven different mutations were detected, nine of which were previously reported and the other two (c.130T > G and c.178T > G) were novel. Homozygous GJB2 mutations were observed in 22.5% and 20% of all the subjects from Isfahan and Hamedan provinces, respectively. c.35delG was the most frequent mutation. One compound heterozygous genotype (c.358_360delGAG/c.35delG) was observed for c.35delG. Screening for the two GJB6 deletions did not reveal any positive sample among heterozygous or GJB2 negative samples. CONCLUSIONS The present study suggests that mutations in the GJB2 gene specially c.35delG are important causes of ARNSHL in the center and west of Iran. Totally, 15% of the patients were heterozygous carriers. Further investigation is needed to detect the genetic cause of HL in the patients with monoallelic GJB2 mutations.
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Shaikh H, Waryah AM, Narsani AK, Iqbal M, Shahzad M, Waryah YM, Shaikh N, Mahmood A. Genetic Testing of Non-familial Deaf Patients for CIB2 and GJB2 Mutations: Phenotype and Genetic Counselling. Biochem Genet 2017; 55:410-420. [PMID: 29086887 DOI: 10.1007/s10528-017-9828-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Accepted: 09/19/2017] [Indexed: 02/02/2023]
Abstract
CIB2 and GJB2 genes variants contribute significantly in familial cases of prelingual recessive hearing loss (HL). This study was aimed to determine the CIB2 and GJB2 variants and associated phenotype in 150 non-familial individuals with HL. After getting informed consent, 150 non-familial deaf patients were enrolled and blood samples were obtained for DNA extraction. Pure tone air conduction audiometry was performed. Coding exons of CIB2 and GJB2 genes were Sanger sequenced. A tetra primer ARMS assay was developed for recurrent CIB2 variant. Four bi-allelic GJB2 variants, c.71G>A p.(Trp24*), c.231G>A p.(Trp77*), c.235delC p.(Leu79Cysfs3*) and c.35delG p.(Gly11Leufs24*), were found in nine hearing impaired individuals. We also found four homozygotes and five carriers of c.380G>A p. (Arg127His) variant of controversial clinical significance. CIB2 sequencing revealed single recurrent variant c.272T>C p. (Phe91Ser) segregating with HL in ten individuals. Among our patients, c.71G>A (p.Trp24*) was the most common variant, accounted for 45% of GJB2 variants. Two known GJB2 variants, c.235delC p. (Leu79Cysfs3*) and c.310del14 p. (Lys105Argfs2*), are reported here for the first time in Pakistani population. Our data further support the benign nature of c.380G>A p. (Arg127His) variant. For CIB2, c.272T>C p. (Phe91Ser) is the second common cause of HL among our sporadic cases. Phenotypically, in our patients, individuals homozygous for GJB2 variants had profound HL, whereas CIB2 homozygotes had severe to profound prelingual HL. Our results suggest that GJB2 and CIB2 are common cause of HL in different Pakistani ethnicities.
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Affiliation(s)
- Hina Shaikh
- Molecular Biology and Genetics Department, Medical Research Center, Liaquat University of Medical and Health Sciences, Jamshoro, Pakistan
| | - Ali M Waryah
- Molecular Biology and Genetics Department, Medical Research Center, Liaquat University of Medical and Health Sciences, Jamshoro, Pakistan.
| | - Ashok K Narsani
- Institute of Ophthalmology, Liaquat University of Medical and Health Sciences, Jamshoro, Pakistan
| | - Muhammad Iqbal
- Department of Biochemistry and Biotechnology, Islamia University, Bahawalpur, Pakistan
| | - Mohsin Shahzad
- Department of Molecular Biology, Shaheed Zulfiqar Ali Bhutto Medical University, Islamabad, Pakistan
| | - Yar M Waryah
- Molecular Biology and Genetics Department, Medical Research Center, Liaquat University of Medical and Health Sciences, Jamshoro, Pakistan
| | - Naila Shaikh
- Molecular Biology and Genetics Department, Medical Research Center, Liaquat University of Medical and Health Sciences, Jamshoro, Pakistan
| | - Amber Mahmood
- Molecular Biology and Genetics Department, Medical Research Center, Liaquat University of Medical and Health Sciences, Jamshoro, Pakistan
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Subaşıoğlu A, Duman D, Sırmacı A, Bademci G, Carkıt F, Somdaş MA, Erkan M, Tekin M, Dündar M. Research of genetic bases of hereditary non-syndromic hearing loss. Turk Arch Pediatr 2017; 52:122-132. [PMID: 29062245 DOI: 10.5152/turkpediatriars.2017.4254] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2016] [Accepted: 03/13/2017] [Indexed: 11/22/2022]
Abstract
AIM Hearing loss is the most common sensory disorder that affects approximately one per 1000 live births. With this project, we aimed to identify gene variants that were common causes of hearing loss in Turkey to contribute to the planning of genetic screening programs for hearing loss, as well as to improve genetic counseling to affected families. MATERIAL AND METHODS Twenty-one families with at least two affected individuals and parental consanguinity who presented with non-syndromic severe-to-profound sensorineural hearing loss were included in this study. We first screened for mutations in GJB2 and mitochondrial DNA 12S RNA genes. Subsequently, we genotyped the TMIE c.250C>T and SNP markers flanking the SLC26A4, MYO7A, MYO15A, OTOF, CDH23, TMIE, TECTA, PCDH15, TMC1, TMPRSS3, TMHS genes in the remaining twelve families without mutations in GJB2. RESULTS Screening for mutations in GJB2 gene showed c.[35delG];[35delG] mutation in four families, c.[35delG];[507C>A] mutation in two families, c.[35delG];[-23+1G>A] mutation in one family, and c.457G>A heterozygous mutation in one family. Genotyping SNP markers showed the c.[250C>T];[250C>T] mutation in TMIE in one family. A homozygous region with SNP genotypes was detected with the OTOF gene in one family, the TMPRSS3 gene in another family, and also a homozygous region was detected with TMHS, OTOF, and TMPRSS3 genes in another family. CONCLUSIONS Further research will be required to determine the genetic bases of hearing loss in families with non-syndromic hearing loss.
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Affiliation(s)
- Aslı Subaşıoğlu
- Department of Medical Genetics, Erciyes University Faculty of Medicine, Kayseri, Turkey
| | - Duygu Duman
- Department of Pediatrics, Division of Pediatric Genetic Diseases, Ankara University Faculty of Medicine, Ankara, Turkey
| | - Aslı Sırmacı
- Division of Human Genetics, John T. Macdonald, Miami University Miller Medical Faculty, Miami, USA
| | - Güney Bademci
- Division of Human Genetics, John T. Macdonald, Miami University Miller Medical Faculty, Miami, USA
| | - Fehime Carkıt
- Division of Odiology, Kayseri Education and Research Hospital, Kayseri, Turkey
| | - Mehmet Akif Somdaş
- Department of Otolaryngology, Erciyes University Faculty of Medicine, Kayseri, Turkey
| | - Mustafa Erkan
- Department of Otolaryngology, Erciyes University Faculty of Medicine, Kayseri, Turkey
| | - Mustafa Tekin
- Division of Human Genetics, John T. Macdonald, Miami University Miller Medical Faculty, Miami, USA
| | - Munis Dündar
- Department of Medical Genetics, Erciyes University Faculty of Medicine, Kayseri, Turkey
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Beheshtian M, Babanejad M, Azaiez H, Bazazzadegan N, Kolbe D, Sloan-Heggen C, Arzhangi S, Booth K, Mohseni M, Frees K, Azizi MH, Daneshi A, Farhadi M, Kahrizi K, Smith RJ, Najmabadi H. Heterogeneity of Hereditary Hearing Loss in Iran: a Comprehensive Review. ARCHIVES OF IRANIAN MEDICINE 2017; 19:720-728. [PMID: 27743438 DOI: 0161910/aim.0010] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
A significant contribution to the causes of hereditary hearing impairment comes from genetic factors. More than 120 genes and 160 loci have been identified to be involved in hearing impairment. Given that consanguine populations are more vulnerable to most inherited diseases, such as hereditary hearing loss (HHL), the genetic picture of HHL among the Iranian population, which consists of at least eight ethnic subgroups with a high rate of intermarriage, is expected to be highly heterogeneous. Using an electronic literature review through various databases such as PubMed, MEDLINE, and Scopus, we review the current picture of HHL in Iran. In this review, we present more than 39 deafness genes reported to cause non-syndromic HHL in Iran, of which the most prevalent causative genes include GJB2, SLC26A4, MYO15A, and MYO7A. In addition, we highlight some of the more common genetic causes of syndromic HHL in Iran. These results are of importance for further investigation and elucidation of the molecular basis of HHL in Iran and also for developing a national diagnostic tool tailored to the Iranian context enabling early and efficient diagnosis of hereditary hearing impairment.
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Affiliation(s)
- Maryam Beheshtian
- Genetics Research Center, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran
| | - Mojgan Babanejad
- Genetics Research Center, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran
| | - Hela Azaiez
- Department of Otolaryngology, University of Iowa Hospitals and Clinics, Iowa City, Iowa, USA
| | - Niloofar Bazazzadegan
- Genetics Research Center, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran
| | - Diana Kolbe
- Department of Otolaryngology, University of Iowa Hospitals and Clinics, Iowa City, Iowa, USA
| | - Christina Sloan-Heggen
- Department of Otolaryngology, University of Iowa Hospitals and Clinics, Iowa City, Iowa, USA
| | - Sanaz Arzhangi
- Genetics Research Center, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran
| | - Kevin Booth
- Department of Otolaryngology, University of Iowa Hospitals and Clinics, Iowa City, Iowa, USA
| | - Marzieh Mohseni
- Genetics Research Center, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran
| | - Kathy Frees
- Department of Otolaryngology, University of Iowa Hospitals and Clinics, Iowa City, Iowa, USA
| | | | - Ahmad Daneshi
- Head and Neck Surgery Department and Research Center, Iran University of Medical Sciences, Tehran, Iran
| | - Mohammad Farhadi
- Head and Neck Surgery Department and Research Center, Iran University of Medical Sciences, Tehran, Iran
| | - Kimia Kahrizi
- Genetics Research Center, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran
| | - Richard Jh Smith
- Department of Otolaryngology, University of Iowa Hospitals and Clinics, Iowa City, Iowa, USA
| | - Hossein Najmabadi
- Genetics Research Center, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran
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GJB2 mutations in Turkish patients with nonsyndromic hearing loss. Meta Gene 2016. [DOI: 10.1016/j.mgene.2016.10.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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16
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Sipeky C, Matyas P, Melegh M, Janicsek I, Szalai R, Szabo I, Varnai R, Tarlos G, Ganczer A, Melegh B. Lower carrier rate of GJB2 W24X ancestral Indian mutation in Roma samples from Hungary: implication for public health intervention. Mol Biol Rep 2014; 41:6105-10. [PMID: 24969484 DOI: 10.1007/s11033-014-3488-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2013] [Accepted: 06/17/2014] [Indexed: 11/29/2022]
Abstract
The purpose of this work was to characterise the W24X mutation of the GJB2 gene in order to provide more representative and geographicaly relevant carrier rates of healthy Roma subisolates and the Hungarian population. 493 Roma and 498 Hungarian healthy subjects were genotyped for the GJB2 c.71G>A (rs104894396, W24X) mutation by PCR-RFLP assay and direct sequencing. This is the first report on GJB2 W24X mutation in geographically subisolated Roma population of Hungary compared to local Hungarians. Comparing the genotype and allele frequencies of GJB2 rs104894396 mutation, significant difference was found in GG (98.4 vs. 99.8 %), GA (1.62 vs. 0.20 %) genotypes and A (0.8 vs. 0.1 %) allele between the Roma and Hungarian populations, respectively (p < 0.02). None of the subjects of Roma and Hungarian samples carried the GJB2 W24X AA genotype. Considerable result of our study, that the proportion of GJB2 W24X GA heterozygotes and the A allele frequency was eight times higher in Roma than in Hungarians. Considering the results, the mutant allele frequency both in Roma (0.8 %) and in Hungarian (0.1 %) populations is lower than expected from previous results, likely reflecting local differentiated subisolates of these populations and a suspected lower risk for GJB2 mutation related deafness. However, the significant difference in GJB2 W24X carrier rates between the Roma and Hungarians may initiate individual diagnostic investigations and effective public health interventions.
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Affiliation(s)
- Csilla Sipeky
- Department of Medical Genetics, Clinical Centre, University of Pecs, Szigeti 12, Pecs, 7624, Hungary,
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Salvago P, Martines E, La Mattina E, Mucia M, Sammarco P, Sireci F, Martines F. Distribution and phenotype of GJB2 mutations in 102 Sicilian patients with congenital non syndromic sensorineural hearing loss. Int J Audiol 2014; 53:558-63. [PMID: 24793888 DOI: 10.3109/14992027.2014.905717] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
OBJECTIVE To evaluate the frequency of GJB2 mutations and their correlation with phenotype in Sicilian non-syndromic sensorineural hearing loss (NSHL) patients. DESIGN Sequencing of the coding region, basal promoter, exon 1, and donor splice site of the GJB2 gene; screening for the presence of the two common GJB6 deletions. STUDY SAMPLE A cohort of 102 Sicilian NSHL patients. RESULTS Fifteen different mutations in GJB2 and seventeen different genotypes were detected. No GJB6 mutations were found. The hearing impairment was profound in the 64.72% of probands (mean PTA0.25-4 kHz of 88.82 ± 26.52 dB HL). A total of 81.37% of patients harboured at least one c.35delG allele; c.167delT and c.-23 + 1G> A were identified in 10.78% and the 9.8% of patients respectively; c.35delG homozygotes presented more severe hearing impairment (75.59% of profound hearing loss) and a higher mean PTA0.25-4 kHz (96.79 ± 21.11 dB HL) with respect to c.35delG/non-c.35delG and c.35delG/Wt patients (P < 0.05). CONCLUSIONS This work underlines the role of c.35delG, c.167delT and c.-23 + 1G> A as the most frequent causes of NSHL in Sicily. The c.35delG frequency found is similar to those reported in other populations of the Mediterranean area. The analysis of genetic and audiologic data confirmed a variability in the phenotype associated to a single genotype.
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Affiliation(s)
- Pietro Salvago
- * Dipartimento di Biomedicina Sperimentale e Neuroscienze Cliniche, (BioNeC), Sezione di Otorinolaringoiatria, Università degli Studi di Palermo , Palermo , Italy
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18
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Bonyadi MJ, Fotouhi N, Esmaeili M. Spectrum and frequency of GJB2 mutations causing deafness in the northwest of Iran. Int J Pediatr Otorhinolaryngol 2014; 78:637-40. [PMID: 24529908 DOI: 10.1016/j.ijporl.2014.01.022] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/23/2013] [Revised: 01/17/2014] [Accepted: 01/19/2014] [Indexed: 10/25/2022]
Abstract
OBJECTIVE Mutations in GJB2 and GJB6 which comprise DFNB1 locus cause up to half of all cases of the prelingual autosomal recessive non-syndromic hearing loss (ARNSHL) worldwide. This study has intended to assess the spectrum and frequency of GJB2/GJB6 mutations in northwest of Iran. METHODS 508 Patients with presumed ARNSHL were analyzed by applying ARMS-PCR, SSCP, PCR-RFLP and sequencing assays. RESULTS Seventy-five (14.7%) different homozygous and eighty-seven (17.1%) different compound heterozygous genotypes were detected in this cohort. Concerning the GJB2 gene, c.35delG was the most prevalent mutation, accounting for 16.4% of the samples. In addition 29 sequence variations other than c.35delG mutation were distinguished in GJB2; namely, delE120, Ins A 290-291, R143Q, V37I, R32H, Y155X, V27I + T123N, F154F, 167delT, 312del14, 299-300delA, T8M, W24X, E114G + V27I, 235delC, R184P, V153I, S139N, A171T, M163V (unknown mutation), G127V, E147X, R127H, 35insG, R143W, V27I, G160S, E114G and IVS1 + 1G > A. Moreover, the IVS1 + 1G > A was accounted as a second common mutation. CONCLUSIONS Overall, the frequency of GJB2 mutations (≥31%) is in agreement with other white population. These findings highlight the importance of the study of GJB2 gene in the diagnosis to provide early treatment and genetic counseling.
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Affiliation(s)
- Mortaza J Bonyadi
- Center of Excellence for Biodiversity, Faculty of Natural Sciences, University of Tabriz, Tabriz, Iran; Liver and Gastrointestinal Disease Research Center, Tabriz University of Medical Sciences, Tabriz, Iran.
| | - Nikou Fotouhi
- Liver and Gastrointestinal Disease Research Center, Tabriz University of Medical Sciences, Tabriz, Iran.
| | - Mohsen Esmaeili
- Institute of Human Genetics, Jena University Hospital, Jena, Germany.
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19
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Chan DK, Chang KW. GJB2-associated hearing loss: Systematic review of worldwide prevalence, genotype, and auditory phenotype. Laryngoscope 2013; 124:E34-53. [DOI: 10.1002/lary.24332] [Citation(s) in RCA: 183] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/10/2013] [Indexed: 12/17/2022]
Affiliation(s)
- Dylan K. Chan
- Department of Otolaryngology-Head and Neck Surgery; University of California; San Francisco U.S.A
| | - Kay W. Chang
- Department of Otolaryngology-Head and Neck Surgery; Stanford University School of Medicine; Stanford California U.S.A
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Connexin 26 and 30 mutations in paediatric patients with congenital, non-syndromic hearing loss treated with cochlear implantation in Mediterranean Turkey. The Journal of Laryngology & Otology 2012; 127:33-7. [PMID: 23171692 DOI: 10.1017/s0022215112002587] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
AbstractObjective:Mutations in the genes for connexin 26 (GJB2) and connexin 30 (GJB6) play an important role in autosomal recessive, non-syndromic hearing loss. This study aimed to detect the 35delG and 167delT mutations of theGJB2gene and the del(GJB6-D13S1830) mutation of theGJB6gene in paediatric patients diagnosed with congenital, non-syndromic hearing loss and treated with cochlear implantation in Mediterranean Turkey.Materials and method:We included 94 children diagnosed with congenital, non-syndromic hearing loss and treated with cochlear implantation. Blood samples were collected, DNA extracted and an enzyme-linked immunosorbent assay performed to enable molecular diagnosis of mutations.Results:Of the 94 children analysed, the 35delG mutation was detected in 12 (12.7 per cent): 10 (83.3 per cent) were homozygous and 2 (16.7 per cent) heterozygous mutant. The 167delT and del(GJB6-D13S1830) mutations were not detected.Conclusion:The GJB2-35delG mutation is a major cause of congenital, non-syndromic hearing loss in this study population.
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Babanejad M, Fattahi Z, Bazazzadegan N, Nishimura C, Meyer N, Nikzat N, Sohrabi E, Najmabadi A, Jamali P, Habibi F, Smith RJH, Kahrizi K, Najmabadi H. A comprehensive study to determine heterogeneity of autosomal recessive nonsyndromic hearing loss in Iran. Am J Med Genet A 2012; 158A:2485-92. [PMID: 22903915 DOI: 10.1002/ajmg.a.35572] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2012] [Accepted: 06/23/2012] [Indexed: 11/05/2022]
Abstract
Hearing loss is the most common sensory disorder worldwide and affects 1 of every 500 newborns. In developed countries, at least 50% of cases are genetic, most often resulting in nonsyndromic deafness (70%), which is usually autosomal recessive (∼80%). Although the cause of hearing loss is heterogeneous, mutations in GJB2 gene at DFNB1 locus are the major cause of autosomal recessive nonsyndromic hearing loss (ARNSHL) in many populations. Our previous study showed that mutations of GJB2 gene do not contribute to the major genetic load of deafness in the Iranian population (∼16%). Therefore, to define the importance of other genes in contributing to an ARNSHL phenotype in the Iranian population, we used homozygosity mapping to identify regions of autozygosity-by-descent in 144 families which two or more progeny had ARNSHL but were negative for GJB2 gene mutations. Using flanking or intragenic short-tandem repeat markers for 33 loci we identified 33 different homozygous variations in 10 genes, of which 9 are novel. In aggregate, these data explain ∼40% of genetic background of ARNHSL in the Iranian population.
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Affiliation(s)
- Mojgan Babanejad
- Genetics Research Center, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran
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Bazazzadegan N, Nikzat N, Fattahi Z, Nishimura C, Meyer N, Sahraian S, Jamali P, Babanejad M, Kashef A, Yazdan H, Sabbagh Kermani F, Taghdiri M, Azadeh B, Mojahedi F, Khoshaeen A, Habibi H, Reyhanifar F, Nouri N, Smith RJH, Kahrizi K, Najmabadi H. The spectrum of GJB2 mutations in the Iranian population with non-syndromic hearing loss--a twelve year study. Int J Pediatr Otorhinolaryngol 2012; 76:1164-74. [PMID: 22695344 DOI: 10.1016/j.ijporl.2012.04.026] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/28/2012] [Revised: 04/25/2012] [Accepted: 04/27/2012] [Indexed: 10/28/2022]
Abstract
OBJECTIVE Mutations in GJB2, encoding connexin 26 (CX26), are causally related to autosomal recessive form of non-syndromic hearing loss (NSHL) at the DFNB1 locus and autosomal dominant NSHL at the DFNA3 locus. In this study, we investigated the prevalence of GJB2 mutations in the Iranian deaf population. METHODS A total of 2322 deaf probands presenting the ethnically diverse Iranian population were screened for variants in GJB2. All persons were first screened for the c.35delG mutation, as this variant is the most prevalent GJB2-deafness causing mutation in the Iranian population. In all persons carrying zero or one c.35delG allele, exons 1 and 2 were then sequenced. RESULTS In total, 374 (~16%) families segregated GJB2-related deafness caused by 45 different mutations and 5 novel variants. The c.35delG mutation was most commonly identified and accounts for ~65% of the GJB2 mutations found in population studied. CONCLUSION Our data also show that there is a gradual decrease in the frequency of the c.35delG mutation and of GJB2-related deafness in general in a cline across Iran extending from the northwest to southeast.
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Affiliation(s)
- Niloofar Bazazzadegan
- Genetics Research Centre, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran
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Davarnia B, Babanejad M, Fattahi Z, Nikzat N, Bazazzadegan N, Pirzade A, Farajollahi R, Nishimura C, Jalalvand K, Arzhangi S, Kahrizi K, Smith RJH, Najmabadi H. Spectrum of GJB2 (Cx26) gene mutations in Iranian Azeri patients with nonsyndromic autosomal recessive hearing loss. Int J Pediatr Otorhinolaryngol 2012; 76:268-71. [PMID: 22172221 DOI: 10.1016/j.ijporl.2011.11.019] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/24/2011] [Revised: 11/16/2011] [Accepted: 11/18/2011] [Indexed: 10/14/2022]
Abstract
OBJECTIVE Hereditary hearing impairment is a genetically heterogeneous disorder. In spite of this, mutations in the GJB2 gene, encoding connexin 26 (Cx26), are a major cause of nonsyndromic recessive hearing loss in many countries and are largely dependent on ethnic groups. The purpose of our study was to characterize the type and prevalence of GJB2 mutations among Azeri population of Iran. METHODS Fifty families presenting autosomal recessive nonsyndromic hearing loss from Ardabil province of Iran were studied for mutations in GJB2 gene. All DNA samples were screened for c.35delG mutation by ARMS PCR. Samples from patients who were normal for c.35delG were analyzed for the other variations in GJB2 by direct sequencing. In the absence of mutation detection, GJB6 was screened for the del(GJB6-D13S1830) and del(GJB6-D13S1854). RESULT Thirteen families demonstrated alteration in the Cx26 (26%). The 35delG mutation was the most common one, accounting for 69.2% (9 out of 13 families). All the detected families were homozygous for this mutation. Two families were homozygous for delE120 and 299-300delAT mutations. We also identified a novel mutation: c.463-464 delTA in 2 families resulting in a frame shift mutation. CONCLUSION Our results suggest that c.35delG mutation in the GJB2 gene is the most important cause of GJB2 related deafness in Iranian Azeri population.
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Affiliation(s)
- Behzad Davarnia
- Genetics Research Centre, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran
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Bonyadi M, Fotouhi N, Esmaeili M. Prevalence of IVS1+1G>A mutation among Iranian Azeri Turkish patients with autosomal recessive non-syndromic hearing loss (ARNSHL). Int J Pediatr Otorhinolaryngol 2011; 75:1612-5. [PMID: 22000900 DOI: 10.1016/j.ijporl.2011.09.024] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/27/2011] [Revised: 09/17/2011] [Accepted: 09/20/2011] [Indexed: 11/28/2022]
Abstract
OBJECTIVE Mutations in the GJB2 gene has been reported as a main cause for autosomal recessive non-syndromic hearing loss (ARNSHL) all over the world. IVS1+1G>A which is splice site mutation have been detected in several populations as disruptive mutation. This study has intended to assess the significance of this mutation, IVS1+1G>A, to the autosomal recessive non-syndromic genetic load among Iranian Azeri Turkish patients. METHODS Following our previous study, one hundred and seventy four unrelated patients with prelingual ARNSL were included in this study. Thirty nine patients had only one identified mutated allele, whereas hundred and thirty five patients were negative for coding region of GJB2. All these patients were screened for IVS1+1G>A by applying PCR-RFLP assay. RESULTS Among studied patients nine compound heterozygote with 35delG, delE120, 235delC were identified. Additionally, six patients were detected with only one IVS1+1G>A mutated allele. In these patients, the other mutated allele was left unidentified. One patient was identified to be homozygous for IVS1+1G>A. Further studies carried out on parents of positive cases, showed that one of the healthy parents (mother) to be homozygous for IVS1+1G>A mutation. By self-report, this person had no hearing impairment, although it is possible that she has mild or moderate hearing loss, which she is unable to detect. Her child was compound heterozygous (IVS1+1G>A/35delG) with profound deafness. The frequency of IVS1+1G>A was found to be about 4.9%, however the parental consanguinity was observed in 37.5% of IVS1+1G>A-mutated families. CONCLUSIONS Our results support founder effect regarding these mutations and the presence of an ancient ancestor is strengthened in comparison to hot spot hypothesis. Also the results suggest variable expressivity of IVS1+1G>A mutation with respect to hearing loss.
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Affiliation(s)
- Mortaza Bonyadi
- Center of Excellence for Biodiversity, Faculty of Natural Sciences, University of Tabriz, Tabriz, Iran.
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Teek R, Kruustük K, Zordania R, Joost K, Reimand T, Möls T, Oitmaa E, Kahre T, Tõnisson N, Ounap K. Prevalence of c.35delG and p.M34T mutations in the GJB2 gene in Estonia. Int J Pediatr Otorhinolaryngol 2010; 74:1007-12. [PMID: 20708129 DOI: 10.1016/j.ijporl.2010.05.026] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/19/2010] [Revised: 05/18/2010] [Accepted: 05/23/2010] [Indexed: 10/19/2022]
Abstract
OBJECTIVE The purpose of this study was to determine the prevalence of c.35delG and p.M34T mutations in the GJB2 gene among children with early onset hearing loss and within a general population of Estonia. METHODS Using an arrayed primer extension assay, we screened 233 probands with early childhood onset hearing loss for 107 different mutations in the GJB2 gene. We then looked for the two most common mutations, c.35delG and p.M34T, in a population of 998 consecutively born Estonian neonates to determine the frequency of these mutations in the general population. RESULTS In 115 (49%) of the patients with early onset hearing loss, we found a mutation in at least one allele of the GJB2 gene. Seventy-three (31%) were homozygous for the c.35delG mutation, seven (3%) were homozygous for the p.M34T mutation, and five (2%) had c35delG/p.M34T compound heterozygosity. Other six identified mutations in GJB2 gene occurred rarely. Among the 998 anonymous newborn samples, we detected 45 who were heterozygous for c.35delG, 2 individuals homozygous for c.35delG, and 58 who were heterozygous for p.M34T. Additionally, we detected two c.35delG/p.M34T compound heterozygotes. CONCLUSION The most common GJB2 gene mutations in Estonian children with early onset hearing loss were c.35delG and p.M34T, with c.35delG accounting for 75% of GJB2 alleles. The carrier frequency for c.35delG and p.M34T in a general population of Estonia was 1 in 22 and 1 in 17, respectively, and was higher than in most other countries.
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Affiliation(s)
- Rita Teek
- Department of Genetics, United Laboratories, Tartu University Hospital, Tartu, Estonia
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Prospective variants screening of connexin genes in children with hearing impairment: genotype/phenotype correlation. Hum Genet 2010; 128:303-13. [DOI: 10.1007/s00439-010-0856-x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2010] [Accepted: 06/23/2010] [Indexed: 10/19/2022]
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Yilmaz A, Menevse S, Bayazit Y, Karamert R, Ergin V, Menevse A. Two Novel Missense Mutations in the Connexin 26 Gene in Turkish Patients with Nonsyndromic Hearing Loss. Biochem Genet 2009; 48:248-56. [DOI: 10.1007/s10528-009-9314-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2008] [Accepted: 08/21/2009] [Indexed: 11/28/2022]
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Hamid M, Karimipoor M, Chaleshtori MH, Akbari MT. A novel 355–357delGAG mutation and frequency of connexin-26 (GJB2) mutations in Iranian patients. J Genet 2009; 88:359-62. [DOI: 10.1007/s12041-009-0054-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Bonyadi M, Esmaeili M, Abhari M, Lotfi A. Mutation Analysis of FamilialGJB2-Related Deafness in Iranian Azeri Turkish Patients. Genet Test Mol Biomarkers 2009; 13:689-92. [DOI: 10.1089/gtmb.2009.0026] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Mortaza Bonyadi
- Faculty of Natural Sciences, Center of Excellence for Biodiversity, University of Tabriz, Tabriz, Iran
- Liver and Gastrointestinal Disease Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Mohsen Esmaeili
- Liver and Gastrointestinal Disease Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Masoumeh Abhari
- Faculty of Natural Sciences, Center of Excellence for Biodiversity, University of Tabriz, Tabriz, Iran
| | - Alireza Lotfi
- Department of Otorhinolaryngology, Faculty of Medicine, Tabriz University of Medical Sciences, Tabriz, Iran
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Abidi O, Boulouiz R, Nahili H, Bakhouch K, Wakrim L, Rouba H, Chafik A, Hassar M, Barakat A. Carrier frequencies of mutations/polymorphisms in the connexin 26 gene (GJB2) in the Moroccan population. ACTA ACUST UNITED AC 2009; 12:569-74. [PMID: 19072567 DOI: 10.1089/gte.2008.0063] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Mutations in the Connexin 26 gene (GJB2/Cx26) are responsible for more than half of all cases of prelingual nonsyndromic recessive deafness in Caucasians. The carrier frequency of the 35delG-GJB2 mutation was found to be as high as 2-4% in the Mediterranean populations. Different GJB2 mutations were reported in the Moroccan patients with autosomal recessive nonsyndromic hearing loss; however, rare studies were carried out on the carrier frequencies of these mutations in the healthy populations. The aim of this study was to estimate the carrier frequencies of the GJB2 mutations in the Moroccan population. The molecular analysis of the 35delG mutation and other GJB2 sequence variations was performed in 386 healthy unrelated Moroccan individuals with no known hearing loss. Five GJB2 sequence variations at heterozygous state were found: two mutations, 35delG and 109G > A (V37I), and three polymorphisms, 79G > A (V27I), 341G > A (E114G), and 457G > A (V153I). The carrier frequency of the 35delG mutation was the highest with 2.07% [95% confidence interval (0.90-4.04%)], followed by that of the V37I mutation with 1.43% (0.06-5.39). The carrier frequency of V27I, E114G, and V153I changes was estimated to be 0.71% (0.01-4.34). This finding shows that the 35delG carrier frequency found here is similar to the one observed in Mediterranean populations. It provides new information about GJB2 carrier rates facilitating the diagnosis and the genetic counseling in the Moroccan population.
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Affiliation(s)
- Omar Abidi
- Laboratory of Human Genetics, Department of Scientific Research, Pasteur Institute, Casablanca, Morocco
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Hoang Dinh E, Ahmad S, Chang Q, Tang W, Stong B, Lin X. Diverse deafness mechanisms of connexin mutations revealed by studies using in vitro approaches and mouse models. Brain Res 2009; 1277:52-69. [PMID: 19230829 DOI: 10.1016/j.brainres.2009.02.008] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2009] [Revised: 02/01/2009] [Accepted: 02/04/2009] [Indexed: 12/12/2022]
Abstract
Mutations in connexins (Cxs), the constitutive protein subunits of gap junction (GJ) intercellular channels, are one of the most common human genetic defects that cause severe prelingual non-syndromic hearing impairments. Many subtypes of Cxs (e.g., Cxs 26, 29, 30, 31, 43) and pannexins (Panxs) are expressed in the cochlea where they contribute to the formation of a GJ-based intercellular communication network. Cx26 and Cx30 are the predominant cochlear Cxs and they co-assemble in most GJ plaques to form hybrid GJs. The cellular localization of specific Cx subtypes provides a basis for understanding the molecular structure of GJs and hemichannels in the cochlea. Information about the interactions among the various co-assembled Cx partners is critical to appreciate the functional consequences of various types of genetic mutations. In vitro studies of reconstituted GJs in cell lines have yielded surprisingly heterogeneous mechanisms of dysfunction caused by various Cx mutations. Availability of multiple lines of Cx-mutant mouse models has provided some insight into the pathogenesis processes in the cochlea of deaf mice. Here we summarize recent advances in understanding the structure and function of cochlear GJs and give a critical review of current findings obtained from both in vitro studies and mouse models on the mechanisms of Cx mutations that lead to cell death in the cochlea and hearing loss.
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Affiliation(s)
- Emilie Hoang Dinh
- Department of Otolaryngology, Emory University School of Medicine, 615 Michael Street, Atlanta, GA 30322-3030, USA
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Abidi O, Boulouiz R, Nahili H, Imken L, Rouba H, Chafik A, Barakat A. The analysis of three markers flanking GJB2 gene suggests a single origin of the most common 35delG mutation in the Moroccan population. Biochem Biophys Res Commun 2008; 377:971-4. [PMID: 18952066 DOI: 10.1016/j.bbrc.2008.10.086] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2008] [Accepted: 10/20/2008] [Indexed: 11/28/2022]
Abstract
In Caucasian populations a single mutation, 35delG, accounts for the majority of GJB2 gene mediated hearing loss, with carrier frequencies estimated between 2-4%, possibly resulting from a founder effect rather than from a mutational hot spot. In Moroccan population, the 35delG mutation accounts for 90.8% of all GJB2 mutated alleles in deaf patients with a carrier frequency of 2.65%. The aim of this study was to evaluate whether the 35delG mutation has derived from a single origin in the Moroccan population. We enrolled 30 unrelated deaf patients homozygous for the 35delG mutation and 165 unrelated control individuals negative for this mutation, and genotyped three microsatellite markers flanking the GJB2 region: D13S141, D13S175 and D13S143. Data analysis revealed that the 35delG mutation is associated with particular alleles of these markers, with significant linkage disequilibrium for the 125 and 105 nucleotide long alleles of D13S141 and D13S175, and that a single specific haplotype accounts for 68% of the chromosomes carrying the 35delG mutation. The estimate age of 35delG mutation is 135 generations or approximately 2700 years old. Like in other Mediterranean populations, our results suggest that in the Moroccan population the 35delG mutation has derived from a single origin in a common founder process.
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Affiliation(s)
- Omar Abidi
- Laboratoire de Génétique Humaine, Département des Recherches Scientifiques, Institut Pasteur, Morocco. 1, Place Louis Pasteur, Casablanca 20100, Morocco.
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Evirgen N, Solak M, Dereköy S, Erdoğan M, Yıldız H, Eser B, Arıkan S, Erkoç A. Genotyping for Cx26 and Cx30 Mutations in Cases with Congenital Hearing Loss. ACTA ACUST UNITED AC 2008; 12:253-6. [DOI: 10.1089/gte.2007.0106] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Affiliation(s)
- Neslihan Evirgen
- Department of Medical Biology, Medical Faculty, Afyonkarahisar Kocatepe University, Afyonkarahisar, Turkey
| | - Mustafa Solak
- Department of Medical Biology, Medical Faculty, Afyonkarahisar Kocatepe University, Afyonkarahisar, Turkey
| | - Sefa Dereköy
- Department of Otolaryngology, Medical Faculty, Afyonkarahisar Kocatepe University, Afyonkarahisar, Turkey
| | - Müjgan Erdoğan
- Department of Medical Biology, Medical Faculty, Afyonkarahisar Kocatepe University, Afyonkarahisar, Turkey
| | - Handan Yıldız
- Department of Medical Biology, Medical Faculty, Afyonkarahisar Kocatepe University, Afyonkarahisar, Turkey
| | - Betül Eser
- Department of Medical Biology, Medical Faculty, Afyonkarahisar Kocatepe University, Afyonkarahisar, Turkey
| | - Suna Arıkan
- Department of Medical Biology, Medical Faculty, Afyonkarahisar Kocatepe University, Afyonkarahisar, Turkey
| | - Arzu Erkoç
- Department of Medical Biology, Medical Faculty, Afyonkarahisar Kocatepe University, Afyonkarahisar, Turkey
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Screening for gap junction protein beta-2 gene mutations in Malays with autosomal recessive, non-syndromic hearing loss, using denaturing high performance liquid chromatography. The Journal of Laryngology & Otology 2008; 122:1284-8. [PMID: 18353197 DOI: 10.1017/s0022215108002041] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
OBJECTIVE To determine the frequency and type of gap junction protein beta-2 gene mutations in Malay patients with autosomal recessive, non-syndromic hearing loss. METHODS A total of 33 Malay patients with autosomal recessive, non-syndromic hearing loss were screened for mutations in the Cx26 coding region. Deoxyribonucleic acid was extracted from buccal swab samples and subjected to polymerase chain reaction. Slow-reannealing was performed, followed by screening using denaturing high performance liquid chromatography. RESULTS Eight of the samples (24.2 per cent) showed heterozygous peaks, and further sequencing of these samples revealed four patients (50.0 per cent) with the W24X mutation, two (25.0 per cent) with the V37I mutation and another two (25.0 per cent) with the G4D mutation. CONCLUSIONS Analysis of buccal swab samples by denaturing high performance liquid chromatography is noninvasive and suitable for rapid and reliable screening of gap junction protein beta-2 gene mutations in patients with autosomal recessive, non-syndromic hearing loss. Malay patients with autosomal recessive, non-syndromic hearing loss have different kinds of gap junction protein beta-2 gene mutations which are rarely found in other populations.
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GJB2 and mitochondrial A1555G gene mutations in nonsyndromic profound hearing loss and carrier frequencies in healthy individuals. J Genet 2008; 87:53-7. [DOI: 10.1007/s12041-008-0007-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Wu CC, Chen PJ, Chiu YH, Lu YC, Wu MC, Hsu CJ. Prospective Mutation Screening of Three Common Deafness Genes in a Large Taiwanese Cohort with Idiopathic Bilateral Sensorineural Hearing Impairment Reveals a Difference in the Results between Families from Hospitals and Those from Rehabilitation Facilities. Audiol Neurootol 2007; 13:172-81. [DOI: 10.1159/000112425] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2007] [Accepted: 08/29/2007] [Indexed: 11/19/2022] Open
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Utrera R, Ridaura V, Rodríguez Y, Rojas MJ, Mago L, Angeli S, Henríquez O. Detection of the 35delG/GJB2 and del(GJB6-D13S1830) Mutations in Venezuelan Patients with Autosomal Recessive Nonsyndromic Hearing Loss. ACTA ACUST UNITED AC 2007; 11:347-52. [DOI: 10.1089/gte.2006.0526] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- René Utrera
- Departamento de Biología Celular, Universidad Simón Bolívar, Caracas, Venezuela 1081-A
| | - Vanessa Ridaura
- Departamento de Biología Celular, Universidad Simón Bolívar, Caracas, Venezuela 1081-A
| | - Yuryanni Rodríguez
- Departamento de Biología Celular, Universidad Simón Bolívar, Caracas, Venezuela 1081-A
| | - Maria J. Rojas
- Departamento de Biología Celular, Universidad Simón Bolívar, Caracas, Venezuela 1081-A
| | - Leomig Mago
- Departamento de Biología Celular, Universidad Simón Bolívar, Caracas, Venezuela 1081-A
| | - Simón Angeli
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, FL 33101
| | - Oswaldo Henríquez
- Departamento de Otorinolaringología, Hospital San Juan de Dios, Caracas, Venezuela 1081-A
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Hernández-Rojas ML, Quiroz-Mercado H, Dalma-Weiszhausz J, Fromow-Guerra J, Amaya-Espinosa A, Solís-Vivanco A, Reyna-Castelán E, Abraham-Marín M, Martínez-Castellanos MA, Aiello LP. Short-term effects of intravitreal bevacizumab for subfoveal choroidal neovascularization in pathologic myopia. Genet Med 2007; 27:707-12. [PMID: 17621179 DOI: 10.1097/gim.0b013e3180a03276] [Citation(s) in RCA: 99] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
PURPOSE To determine short-term effects of intravitreal bevacizumab for subfoveal choroidal neovascularization (CNV) in pathologic myopia. METHODS In this prospective interventional case series, patients were treated with 2.5 mg of intravitreal bevacizumab and followed for 3 months. Best-corrected visual acuity (BCVA), optical coherence tomography (OCT), and fluorescein angiography (FA) were recorded. Indications for retreatment were active leaking CNV shown by FA and presence of subretinal fluid by OCT in combination with visual disturbances. RESULTS Fourteen patients were included, with a mean age of 53.86 +/- 16.26 years (range 29-85). Mean spherical equivalent was -13.87 +/- 3.68 diopters (-7.25 to -20.50). Minimum follow-up was 3 months. There were no adverse events. The mean initial visual acuity was 20/200 improving to 20/100 at 2 weeks, 20/80 at 4 weeks, and 20/60 at 8 and 12 weeks (P=0.007; P=0.001; P=0.005; P=0.001, respectively). Initial foveal thickness improved from 385.43 microm +/- 125.83 microm to 257.64 +/- 76.6 microm and 194.54 +/- 54.35 microm after the first and third month, respectively (P=0.001). CONCLUSIONS Initial treatment results of patients with CNV due to pathologic myopia did not reveal any short-term safety concerns. Intravitreal bevacizumab resulted in a significant decrease in foveal thickness and improvement in visual acuity. These favorable initial results support further larger and long-term studies.
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Affiliation(s)
- Myriam L Hernández-Rojas
- Hospital Luis Sánchez Bulnes, Asociación Para Evitar la Ceguera en México I.A.P., México City, México.
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Esmaeili M, Bonyadi M, Nejadkazem M. Common mutation analysis of GJB2 and GJB6 genes in affected families with autosomal recessive non-syndromic hearing loss from Iran: simultaneous detection of two common mutations (35delG/del(GJB6-D13S1830)) in the DFNB1-related deafness. Int J Pediatr Otorhinolaryngol 2007; 71:869-73. [PMID: 17368814 DOI: 10.1016/j.ijporl.2007.02.007] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/10/2006] [Revised: 02/05/2007] [Accepted: 02/17/2007] [Indexed: 11/28/2022]
Abstract
OBJECTIVE DFNB1 locus has been reported as a major cause of autosomal recessive non-syndromic hearing loss (ARNSHL) worldwide. 35delG and del(GJB6-D13S1830) are thought to be two common mutations in this locus among Caucasians. The aim of this study is to determine the significance of these two mutations in aetiology of ARNSHL in Iran. METHODS One hundred and thirty-three unrelated patients with ARNSHL were tested by using multiplex allele-specific PCR assay after validation by positive control samples. RESULTS The frequency of 35delG was about 18.5%, however, del(GJB6-D13S1830) was not found in the studied patients. Parental consanguinity was observed in 50% of 35delG-mutated families. CONCLUSIONS Our results support founder effect regarding these mutations.
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Affiliation(s)
- Mohsen Esmaeili
- Genetic Lab. Drug Applied Research Center, Biotechnology Research Center, Tabriz University of Medical Sciences, University Ave., Tabriz, Iran
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Kalay E, Caylan R, Kiroglu AF, Yasar T, Collin RWJ, Heister JGAM, Oostrik J, Cremers CWRJ, Brunner HG, Karaguzel A, Kremer H. A novel locus for autosomal recessive nonsyndromic hearing impairment, DFNB63, maps to chromosome 11q13.2-q13.4. J Mol Med (Berl) 2007; 85:397-404. [PMID: 17211611 DOI: 10.1007/s00109-006-0136-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2006] [Revised: 10/19/2006] [Accepted: 10/25/2006] [Indexed: 01/28/2023]
Abstract
Hereditary hearing impairment is a genetically heterogeneous disorder. To date, 49 autosomal recessive nonsyndromic hearing impairment (ARNSHI) loci have been described, and there are more than 16 additional loci announced. In 25 of the known loci, causative genes have been identified. A genome scan and fine mapping revealed a novel locus for ARNSHI (DFNB63) on chromosome 11q13.2-q13.4 in a five-generation Turkish family (TR57). The homozygous linkage interval is flanked by the markers D11S1337 and D11S2371 and spans a 5.3-Mb interval. A maximum two-point log of odds score of 6.27 at a recombination fraction of theta = 0.0 was calculated for the marker D11S4139. DFNB63 represents the eighth ARNSHI locus mapped to chromosome 11, and about 3.33 Mb separate the DFNB63 region from MYO7A (DFNB2/DFNB11). Sequencing of coding regions and exon-intron boundaries of 13 candidate genes, namely SHANK2, CTTN, TPCN2, FGF3, FGF4, FGF19, FCHSD2, PHR1, TMEM16A, RAB6A, MYEOV, P2RY2 and KIAA0280, in genomic DNA from an affected individual of family TR57 revealed no disease-causing mutations.
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Affiliation(s)
- E Kalay
- Department of Human Genetics, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands.
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Hişmi BO, Yilmaz ST, Incesulu A, Tekin M. Effects of GJB2 genotypes on the audiological phenotype: variability is present for all genotypes. Int J Pediatr Otorhinolaryngol 2006; 70:1687-94. [PMID: 16712961 DOI: 10.1016/j.ijporl.2006.03.015] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/21/2005] [Revised: 03/25/2006] [Accepted: 03/30/2006] [Indexed: 10/24/2022]
Abstract
BACKGROUND AND AIM Recent studies have revealed a genotype-phenotype correlation for mutations in the GJB2 gene. Since ethnic difference may have an effect for the degree of hearing loss due to background genes, we aimed to search for confirmation of previously suggested genotype-phenotype correlation in GJB2 deafness in the Turkish population. METHODS Pure tone audiograms of 63 unrelated probands with GJB2-associated hearing loss having 15 different mutations were obtained and evaluated for correlation between the degree of hearing loss and genotypes. RESULTS Three GJB2 genotypes identified in more than one family were homozygous c.35delG (44 probands), homozygous p.E120del (four probands) and c.[35delG]+[IVS1+1G>A] (two probands). No statistical difference for the degree of hearing loss was observed when the genotypes were compared individually or grouped according to their effects on the protein. The most likely explanation for this result is the relatively small size of the studied population. Degree of hearing loss was variable in c.35delG and p.E120del homozygotes. Intra-familial phenotypic variability was present for some genotypes. The detailed audiological data for homozygous p.E120del and c.[35delG]+[328delG] genotypes are reported for the first time in this study. CONCLUSION Previously reported genotype-phenotype correlations for the GJB2 deafness should be cautiously interpreted during the clinical counseling since variability in the degree of hearing loss is present for all GJB2 genotypes.
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Affiliation(s)
- Burcu Oztürk Hişmi
- Division of Genetics, Department of Pediatrics, Ankara University School of Medicine, Ankara, Turkey
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