scholarly journals A novel nonsense mutation c.1121G>A (p.Trp374*) in the CLIC5 gene is the main cause of the juvenile autosomal recessive form of deafness (DFNB103) in the Arctic regions of Yakutia

2019 ◽  
pp. 36-48
Author(s):  
В.Г. Пшенникова ◽  
Г.П. Романов ◽  
Т.М. Николаева ◽  
Ф.М. Терютин ◽  
Т.В. Борисова ◽  
...  
Keyword(s):  
Hearing Loss ◽  
Autosomal Recessive ◽  
Disease Onset ◽  
Premature Stop Codon ◽  
The Arctic ◽  
Gjb2 Gene ◽  
Unknown Etiology ◽  
Homozygous Mutation ◽  
Homozygous Variant ◽  
First Case

Наиболее частой причиной несиндромальной потери слуха являются мутации гена GJB2. Ранее было показано, что в Якутии вклад мутаций гена GJB2 в потерю слуха среди пациентов с врожденной тугоухостью составил 49%. Целью данной работы являлся поиск молекулярно-генетических основ потери слуха среди GJB2-негативных пациентов, у которых причина заболевания осталась неустановленной. В исследование были включены 238 (228 неродственных) GJB2-негативных пациентов, среди которых мы обнаружили одну семью с 5 пораженными индивидами с ювенильной потерей слуха неизвестной этиологии (дебют заболевания варьировал от 0 до 8 лет). Путём полноэкзомного анализа (WES), проведенного у одного из пораженных членов семьи, была выявлена ранее не описанная гомозиготная замена c.1121G>A в 6-ом экзоне гена CLIC5 (6p21.1, OMIM 607293). Данная транзиция приводит к образованию преждевременного стоп-кодона в 374-ой аминокислотной позиции (p.Trp374*), терминирующего синтез полипептидной цепи белка CLIC5 (NP_001107558.1). В гене CLIC5 известна только одна гомозиготная замена c.96T>A (р.Cys32*), которая ранее была найдена в инбредной турецкой семье с постлингвальной прогрессирующей аутосомно-рецессивной глухотой (DFNB103). В настоящей работе гомозиготный вариант c.1121G>A (p.Trp374*) был выявлен у 26 из 238 GJB2-негативных пациентов (10,9%). У большинства из них (19 из 26) отмечается поздний дебют потери слуха в среднем в 9,7±0,6 лет. Аудиологическое обследование у 13 из 26 пациентов выявило преимущественно симметричную сенсоневральную прогрессирующую потерю слуха различной степени тяжести (от донозологической и I-ой степени тугоухости до глухоты). Распространенность DFNB103, обусловленной гомозиготным вариантом c.1121G>A (p.Trp374*) гена CLIC5, в Якутии составила в среднем 0,27±0,05 на 10000 человек с максимальным накоплением в Эвено-Бытантайском национальном районе (31,39±10,46 на 10000 человек), который относится к арктической группе улусов, где большинство населения составляют эвены (53%). Это первый в России случай идентификации орфанного заболевания, накопление которого обнаружено в Арктике. В целом, гомозиготный вариант c.1121G>A (p.Trp374*) гена CLIC5 можно расценивать как каузативный для DFNB103 с высоким вкладом в этиологию нарушений слуха у населения Якутии. The most common cause of non-syndromic hearing loss in various populations of the world is the mutations in the GJB2 gene. Previously it was shown that the pathogenic contribution of the GJB2-mutations among patients with congenital hearing loss in Yakutia was 49%. The aim of this work was to investigate the molecular genetic basis of hearing loss among GJB2-negative patients. The study included 238 (228 unrelated) GJB2-negative patients, among them we found one family with five affected individuals with juvenile hearing loss of unknown etiology (the disease onset varied from 0 to 8 years). Using a whole exome sequencing (WES), performed in one of affected family members, a novel homozygous c.1121G>A (6p21.1, OMIM 607293) substitution in exon 6 of the CLIC5 gene was detected. This substitution leads to the formation of a premature stop codon at the 374 amino acid position (p.Trp374*) which terminates the synthesis of the polypeptide chain of the CLIC5 protein (NP_001107558.1). To date, only one homozygous mutation c.96T>A (p.Cys32*) was known in human gene CLIC5 which was found in one inbred Turkish family with progressive autosomal recessive deafness, type 103 (DFNB103). In our study, a homozygous variant c.1121G>A (p.Trp374*) was detected in 26 out of 238 GJB2-negative patients in Yakutia (10.9%). Most of homozygous for c.1121G>A patients (19 out of 26) reported about late onset of their hearing loss occurred in postlingual period (averaged 9.7±0.6 years). Audiological examination of 13 out of 26 patients revealed predominantly symmetric sensorineural progressive hearing loss of varying severity (from mild to profound hearing loss). The average prevalence of DFNB103 caused by the homozygous variant c.1121G>A (p.Trp374*) in Yakutia was 0.27±0.053 per 10000 with a maximum accumulation in Eveno-Bytantaysky district (31.39±10.46 per 10000) which referred to the Arctic group of districts where the majority of the population is represented by Evens (53%). This is the first case of the identification of the orphan disease with its accumulation in Arctic part of Russia. In general, the homozygous variant c.1121G>A (p.Trp374*) of the CLIC5 gene can be regarded as causative to DFNB103 with a high contribution to the etiology of hearing impairments in the population of Yakutia.

Update of the spectrum of GJB2 gene mutations in Tunisian families with autosomal recessive nonsyndromic hearing loss

Gene ◽  
2013 ◽  
Vol 525 (1) ◽  
pp. 1-4 ◽  
Author(s):  
Zied Riahi ◽  
Hassen Hammami ◽  
Houyem Ouragini ◽  
Habib Messai ◽  
Rim Zainine ◽  
...  
Keyword(s):  
Hearing Loss ◽  
Autosomal Recessive ◽  
Gene Mutations ◽  
Gjb2 Gene ◽  
Nonsyndromic Hearing Loss

An Autosomal-Recessive GFI1B Mutation Defines the Splice Isoform p37 As Essential for Biogenesis of Functional Human Platelets, but Dispensable for Erythropoiesis

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 2644-2644
Author(s):  
Harald Schulze ◽  
Axel Schlagenhauf ◽  
Georgi Manukjan ◽  
Christine Beham-Schmid ◽  
Oliver Andres ◽  
...  
Keyword(s):  
Alternative Splicing ◽  
Growth Factor ◽  
Autosomal Recessive ◽  
Stop Codon ◽  
Zinc Fingers ◽  
Premature Stop Codon ◽  
Index Patient ◽  
Homozygous Mutation ◽  
Recessive Trait ◽  
Erythroid Progenitor

Abstract Growth factor independent 1 (GFI1) and Growth Factor Independent 1B (GFI1B) are zinc finger transcriptional repressors that share about 90% homology on amino acid sequence and are expressed during hematopoiesis. While GFI1 is most important for granulocyte-monocyte lineage commitment, GFI1B is an essential master regulator of erythroid and megakaryocytic lineages. Mice lacking Gfi1b are embryonic lethal due to anemia and thrombocytopenia. In humans, alternative splicing leads to a shorter p32 isoform that lacks the first 2 of 6 zinc fingers. GFI1B germline mutations have been reported to cause autosomal-dominant macrothrombocytopenia with a grey-platelet syndrome phenotype, implying that the mutant protein acts in a dominant-negative manner. We report on a Chechen family from eastern Georgia whose affected family members all present with severe, life-threatening bleeding diathesis. The female index patient had recurrent hematomata and multiple petechiae since childhood. Both of her children (age 9 and 7) present with very low platelet counts (below 45/nL) and a similar cutaneous bleeding pattern like her mother. The brother also had thrombocytopenia and died at age 33 in reponse to a spontaneous cerebral hemorrhage. In contrast, the index patient's husband, her parents and the children of the deceased brother were clinically unaffected. Blood smears of affected patients showed macrothrombocytopenia with reduced May-Grünwald-Giema staining and decreased staining for alpha-granule markers von Willebrand factor (vWF) and P-selectin (CD62P). Platelet function testing revealed reduced responses to ADP, collagen, TRAP-6 and arachidonic acid. White and red blood cell parameters were overall normal in the index patient and the two affected children. We analyzed DNA from the index patient by targeted next generation sequencing for 59 genes relevant for platelet formation or function. We found a novel homozygous single nucleotide insertion in GFI1B (NM_004188.5; c.551insG), which was confirmed by Sanger sequencing and is expected to cause a premature stop-codon. The homozygous mutation co-segregated with the phenotype. The unaffected mother, the husband and two unaffected nephews were heterozygous, suggesting a local founder variant and an unexpected autosomal-recessive trait. Bone marrow analysis showed unaffected myeloid and erythroid cells, but dysplastic micromegakaryocytes with increased CD34 staining. Peripheral blood platelets were also positive for CD34. We performed quantitative real-time PCR of platelet RNA and found residual homozygous c.551_G insertion in the p37 transcript and an unexpected expression of the p32 variant. The p37 transcript was markedly reduced in context with an increased p32/p37 ratio compared to controls. Our findings indicate that the mutated transcript was not completely degraded by nonsense-mediated decay, but mostly subjected to alternative splicing skipping the mutated exon 9. Our findings imply that the first two zinc fingers of GFI1B are dispensable for human erythropoiesis, but essential for normal megakaryopoiesis and the production of functional platelets. While previous mutations affect both isoforms, the insertion variant presented here, results in a premature stop-codon and affects only the p37 isoform due to alternative splicing. This splice variant defines an important node at the megakaryocytic-erythroid progenitor stage and we conclude that the transcriptional regulation of erythropoiesis is uncoupled from that of megakaryopoiesis through alternative splicing of GFI1B. Disclosures No relevant conflicts of interest to declare.

scholarly journals Mutations in the gjb2 gene in children with bilateral hearing loss in Kyrgyzstan

2020 ◽  
Vol 19 (6) ◽  
pp. 64-71
Author(s):  
V. V. Khalfina ◽  
◽  
A. A. Stepanova ◽  
T. G. Markova ◽  
A. V. Polyakov ◽  
...  
Keyword(s):  
Hearing Loss ◽  
Family History ◽  
Molecular Genetic ◽  
Genetic Research ◽  
Gjb2 Gene ◽  
Unknown Etiology ◽  
Compound Heterozygous ◽  
Kyrgyz Republic ◽  
Gene Encoding ◽  
35Delg Mutation

The purpose of this work was to identify and study the prevalence of mutations in the GJB2 gene encoding the connexin 26 protein in the Kyrgyz Republic. Hearing loss is currently the most widespread disease. This paper presents a study of 89 patients with persistent bilateral sensorineural hearing loss and deafness of unknown etiology. All patients were divided into two groups. One group included patients with an unburdened family history, the second group included patients with a burdened family history. When clarifying the etiology of the disease, we can assume further dynamics of the hearing thresholds, as well as select the necessary tactics for managing such patients for early rehabilitation. As a result of molecular genetic research, mutations in the GJB2 gene were detected in 19 patients (21,3%). The 35delG mutation was found in a homozygous state in 5 children from parents of Russian and Tatar origin. In 4 families, parents were in an assorted marriage. Among 62 Kyrgyz, mutations in the GJB2 gene were detected in 9 cases, which accounted for 14,5% of cases. The 35delG mutation among the Kyrgyz was found only in the compound heterozygous state with the 235delC mutation in 3 children and with the –23 + 1G> A mutation in one child.

scholarly journals Audiological features in Serbian patients with hearing impairment identified with c.35delG in the GJB2 gene

2021 ◽  
pp. 98-98
Author(s):  
Bojana Dobric ◽  
Danijela Radivojevic ◽  
Jovana Jecmenica ◽  
Vassos Neocleous ◽  
Pavlos Fanis ◽  
...  
Keyword(s):  
Hearing Loss ◽  
Hearing Impairment ◽  
Autosomal Recessive ◽  
Gjb2 Gene ◽  
Compound Heterozygous ◽  
Heterozygous State ◽  
Phenotype Correlation ◽  
Pathogenic Variants ◽  
Environmental Causes ◽  
35Delg Mutation

Introduction/Objective. Hearing impairment (HI) is the most common sensorineural disorder with an incidence of 1/700-1000 newborns. Variants in the GJB2 gene are the major cause of autosomal recessive nonsyndromic sensorineural hearing loss (ARNSHL). The degree of HI in patients with detected mutations in GJB2 gene ranges from mild to profound. The aim of this study was to determine possible genotype-phenotype association between audiometric characteristics and detected genotypes in ARNSHL patients from Serbia. Methods. Ninety-two patients with ARNSHL underwent genetic analysis with PCR-ARMS and sequencing of the GJB2 gene. Audiological analyses were obtained in all patients using a combination of several methods to estimate the degree of hearing loss. Results. Audiological analysis performed in the 92 probands showed moderate to profound range of hearing loss. All identified pathogenic variants accounted for 42.39% of the mutant alleles (78/184 alleles), with the c.35delG mutation being the most frequent (30.43%). Genotype-phenotype correlation in an isolated group of 37 patients bearing c.35delG in the homozygous, compound heterozygous or heterozygous state. In this group the majority of patients (30/37, 81.08%) exhibited severe to profound hearing deficit. Conclusion. Association between genotype and the degree of hearing impairment in patients analyzed in this study demonstrated that patients with bi-allelic truncating mutations i.e. c.35delG, associate with the more severe hearing loss when compared with those identified with only one affected allele. The various degrees of hearing impairment observed in heterozygous patients could be explained by the presence of an undetected second mutation or other modifier genes or environmental causes.

scholarly journals Identification of Main Genetic Causes Responsible for Non-Syndromic Hearing Loss in a Peruvian Population

Genes ◽  
2019 ◽  
Vol 10 (8) ◽  
pp. 581 ◽  
Author(s):  
Figueroa-Ildefonso ◽  
Bademci ◽  
Rajabli ◽  
Cornejo-Olivas ◽  
Villanueva ◽  
...  
Keyword(s):  
Hearing Loss ◽  
Genetic Factors ◽  
Stop Codon ◽  
Premature Stop Codon ◽  
Gjb2 Gene ◽  
Pathogenic Variants ◽  
Novel Variants ◽  
Syndromic Hearing Loss ◽  
Different Populations ◽  
Global Population

: Hearing loss (HL) is a common sensory disorder affecting over 5% of the global population. The etiology underlying HL includes congenital and acquired causes; genetic factors are the main cause in over 50% of congenital cases. Pathogenic variants in the GJB2 gene are a major cause of congenital non-syndromic hearing loss (NSHL), while their distribution is highly heterogeneous in different populations. To the best of our knowledge, there is no data regarding the genetic etiologies of HL in Peru. In this study, we screened 133 Peruvian families with NSHL living in Lima. We sequenced both exons of the GJB2 gene for all probands. Seven probands with familial NSHL that remained negative for GJB2 variants underwent whole genome sequencing (WGS). We identified biallelic pathogenic variants in GJB2 in 43 probands; seven were heterozygous for only one allele. The c.427C>T variant was the most common pathogenic variant followed by the c.35delG variant. WGS revealed three novel variants in MYO15A in two probands, one of them was predicted to affect splicing and the others produce a premature stop codon. The Peruvian population showed a complex profile for genetic variants in the GJB2 gene, this particular profile might be a consequence of the admixture history in Peru.

A novel frameshift mutation (c.405delC) in the GJB2 gene associated with autosomal recessive hearing loss in two Tunisian families

2013 ◽  
Vol 77 (9) ◽  
pp. 1485-1488 ◽  
Author(s):  
Zied Riahi ◽  
Houda Chahed ◽  
Habib Jaafoura ◽  
Rim Zainine ◽  
Olfa Messaoud ◽  
...  
Keyword(s):  
Hearing Loss ◽  
Autosomal Recessive ◽  
Frameshift Mutation ◽  
Gjb2 Gene

scholarly journals Autosomal Recessive Oculodentodigital Dysplasia: A Case Report and Review of the Literature

2018 ◽  
Vol 154 (4) ◽  
pp. 181-186 ◽  
Author(s):  
Elifcan Taşdelen ◽  
Ceren D. Durmaz ◽  
Halil G. Karabulut
Keyword(s):  
Autosomal Recessive ◽  
Autosomal Dominant ◽  
Stop Codon ◽  
Premature Stop Codon ◽  
Rare Condition ◽  
Clinical Findings ◽  
Homozygous Mutation ◽  
Nasal Bridge ◽  
Oculodentodigital Dysplasia ◽  
Autosomal Recessive Manner

Oculodentodigital dysplasia (ODDD) is a rare condition characterized by a typical facial appearance and variable findings of the eyes, teeth, and fingers. ODDD is caused by mutations in the GJA1 gene in chromosome 6q22 and inherited in an autosomal dominant manner in the majority of the patients. However, in recent clinical reports, autosomal recessive ODDD cases due to by GJA1 mutations were also described. Here, we report on a 14-year-old boy with microphthalmia, microcornea, narrow nasal bridge, hypoplastic alae nasi, prominent columnella, hypodontia, dental caries, and partial syndactyly of the 2nd and 3rd toes. These clinical findings were concordant with the diagnosis of ODDD, and a novel homozygous mutation (c.442C>T, p.Arg148Ter) was determined in the GJA1 gene leading to a premature stop codon. His phenotypically normal parents were found to be carriers of the same mutation. This is the third family in the literature in which ODDD segregates in an autosomal recessive manner.

Secondary, profound, sensorineural hearing loss after recovery from haemolytic uraemic syndrome due to enterohaemorrhagic Escherichia coli, and subsequent cochlear implantation, in two Japanese children

2013 ◽  
Vol 127 (3) ◽  
pp. 306-310
Author(s):  
S B Minami ◽  
H Takegoshi ◽  
Y Shinjo ◽  
K Kaga
Keyword(s):  
Escherichia Coli ◽  
Hearing Loss ◽  
Cochlear Implantation ◽  
Haemolytic Uraemic Syndrome ◽  
Disease Onset ◽  
Profound Hearing Loss ◽  
Enterohaemorrhagic Escherichia Coli ◽  
First Case ◽  
Hearing Function ◽  
One Year

AbstractObjectives:To describe two cases of profound hearing loss secondary to enterohaemorrhagic Escherichia coli infection, and to report the efficacy of subsequent cochlear implantation.Results:The first case was a four-year-old girl admitted to hospital with Escherichia coli O157 infection and haemolytic uraemic syndrome. Mild hearing loss was confirmed five months after discharge, progressing to profound loss three months later. At the age of seven years, she underwent cochlear implantation, with remarkable improvement in speech perception and production. The second case was a three-year-old boy admitted with haemolytic uraemic syndrome caused by Escherichia coli O111 infection. One year after disease onset, profound hearing loss was confirmed. Cochlear implantation at the age of five years produced significant recovery of auditory function.Conclusion:This study represents the first published report of secondary hearing loss after recovery from haemolytic uraemic syndrome caused by enterohaemorrhagic Escherichia coli. It indicates that cochlear implantation can restore hearing function in such patients.

scholarly journals GJB2 and GJB6 genes mutations in children with non-syndromic hearing loss

2017 ◽  
Vol 25 (1) ◽  
pp. 37-46 ◽  
Author(s):  
Călin Lazăr ◽  
Radu Popp ◽  
Camelia Al-Khzouz ◽  
Gheorghe Mihuț ◽  
Paula Grigorescu-Sido
Keyword(s):  
Hearing Loss ◽  
Gjb2 Gene ◽  
Pcr Analysis ◽  
Profound Hearing Loss ◽  
Prevalence Data ◽  
Sample Group ◽  
First Case ◽  
Syndromic Hearing Loss ◽  
The Moment ◽  
Moderate Hearing Loss

Abstract Introduction. At the moment there is not enough data in Romania about the incidence of the main genetic mutations which can cause hearing loss. Objective. The current research aims to determine on a representative sample the prevalence of two mutations of genes GJB2 -c.35delG and p.W24X- and two mutations of genes GJB6 -del(GJB6-D13S1830), del(GJB6-D13S1854) respectively - in patients with congenital nonsyndromic sensorineural hearing loss (CNSHL). Methods: The sample group included 179 children with CNSHL. The evaluation consist in: a.Clinical, laboratory and imagistic examination; b.ENT exam and audiological evaluation. c.Two methods (semi-nested PCR technique followed by RFLP, validated with ARMS-PCR analysis) for detection of c.35delG and pW24X mutations; d.PCR-multiplex technique for detecting del(GJB6-D13S1830) and del (GJB6-D13S1854). Results: The audiological diagnosis was: profound hearing loss in 116 patients (64.8%), severe hearing loss in 29 children (16.2%) and moderate hearing loss in 34 patients (representing 19% of the trial patients). The prevalence for the three mutations was: 27.3 % for c.35delG, 3.6 % for p.W24X and 0.28% for del(GJB6-D13S1830). The detection of the three mutations (two on GJB2 gene and one on GJB 6 gene) has allowed to establish the genetic cause for deafness in 45 patients, representing 25.14% of the sample group. Our study is reporting the first case in Romania with a mutation of gene GJB6. Mutation del(GJB6-D13S1854) lacked in all 179 patients. Conclusion: The prevalence data obtained in the current research are comparable to data communicated by studies from other European countries.

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