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 Spectrum and Frequency of the GJB2 Gene Mutations Among Latvian Patients with Prelingual Nonsyndromic Hearing Loss

2009 ◽  
Vol 63 (4-5) ◽  
pp. 198-203
Author(s):  
Olga Šterna ◽  
Natālija Proņina ◽  
Ieva Grīnfelde ◽  
Sandra Kušķe ◽  
Astrīda Krūmiņa ◽  
...  
Keyword(s):  
Hearing Loss ◽  
Gene Mutations ◽  
Gjb2 Gene ◽  
Connexin 26 ◽  
Compound Heterozygous ◽  
Nonsyndromic Hearing Loss ◽  
Profound Hearing Loss ◽  
Common Cause ◽  
Gjb2 Mutation ◽  
35Delg Mutation

Spectrum and Frequency of the GJB2 Gene Mutations Among Latvian Patients with Prelingual Nonsyndromic Hearing Loss Mutations in the GJB2 gene (connexin 26) are the most common cause of congenital nonsyndromic severe-to-profound hearing loss. Sixty-five hearing impaired probands from Latvia were tested for mutations in the GJB2 gene to determine the percentage of hearing loss attributed to connexin 26 and the types of mutations in this population. A total of 62% of patients tested had GJB2 mutations. Four different mutations in the GJB2 gene were identified in Latvian patients with nonsyndromic sensorineural hearing loss: 35delG, 311-324del14, 235delC and M34T. The most prevalent mutation is 35delG (47% of all probands were homozygous and 8% compound heterozygous). Our findings support the conclusion that the 35delG mutation is the most prevalent GJB2 mutation and that it is the common cause of hereditary nonsyndromic hearing loss in populations of European descent.

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.

Hearing loss associated with 35delG mutation in Connexin-26 (GJB2) gene: audiogram analysis

2004 ◽  
Vol 118 (1) ◽  
pp. 8-11 ◽  
Author(s):  
Fabrizio Salvinelli ◽  
Manuele Casale ◽  
Luca D’Ascanio ◽  
Luca Firrisi ◽  
Fabio Greco ◽  
...  
Keyword(s):  
Hearing Loss ◽  
Autosomal Recessive ◽  
Pure Tone Audiometry ◽  
Gjb2 Gene ◽  
Connexin 26 ◽  
Common Mutation ◽  
Congenital Hearing Loss ◽  
35Delg Mutation ◽  
The Relationship

35delG is the most common mutation in the Connexin-26 gene, representing a major cause of autosomal recessive hearing loss. The aim of this study was to evaluate the relationship between the audiological phenotype and the 35delG mutation in 64 Sicilians with non-syndromic deafness. Pure-tone audiometry and a screening for 35delG mutation were performed. Audiograms were evaluated according to the classification of Liu and Xu. Thirteen homozygotes and nine heterozygotes for the investigated mutation were found. Symmetrical hearing loss was significantly (p=0.008) more common in homozygous subjects than in those without the Connexin-26 mutation. Profound-severe hypoacusia was found in 92.3 per cent of 35delG homozygous, 22.3 per cent of heterozygous and 58.7 per cent of 35delG absent patients. Residual shape audiograms were more frequent in homozygotes. A molecular analysis for the 35delG mutation should be performed in cases of symmetric, severe-profound congenital hearing loss, as a genetic cause is probable in such cases.

Efficiency of SNPs for the Detection of 35DelG Mutation in 50 Cases with Nonsyndromic Hearing Loss

2018 ◽  
Vol 69 (8) ◽  
pp. 2273-2277
Author(s):  
Luminita Radulescu ◽  
Ghenadie Curocichin ◽  
Anastasia Buza ◽  
Sergiu Parii ◽  
Tatiana Meriacre ◽  
...  
Keyword(s):  
Hearing Loss ◽  
Sensitivity And Specificity ◽  
Autosomal Recessive ◽  
Reference Method ◽  
Screening Tests ◽  
Gjb2 Gene ◽  
Single Nucleotide ◽  
Specificity And Sensitivity ◽  
Study Results ◽  
35Delg Mutation

Congenital sensorineural hearing loss (SNHL) is recognized as a major public health burden. Mutations in the GJB2 gene are among the most frequent encountered etiological factors (approximately 50% of cases of autosomal recessive sensorineural non-syndromic hearing loss in the Caucasian population). Single nucleotide polymorphisms (SNPs) are important markers in studies that correlate the genotype with the phenotype. The main purpose of the study is to develop and validate a molecular-genetic screening algorithm based on the SNP rs80338939 for later use in laboratories in Romania and the Republic of Moldova. A prospective study was conducted on 50 randomly included subjects with profound congenital SNHL. The 35delG mutation was assessed by two methods: a reference method (University Medical Center Freiburg, Germany) and the method to validate: single nucleotide polymorphism (SNP) for the same mutation. We compared the results of the two methods to assess the specificity and sensitivity of the method used in the study. Results obtained indicate a sensitivity of 92% and 98% specificity for the studied method when compared with the reference method. The high sensitivity and specificity of the proposed method confirms that rs80338939 can be used as a biomarker in the assessment of the risk of autosomal recessive SNHL. In fact, we aim to optimize the technique to achieve 100% sensitivity and specificity. At the same time, we acknowledge that the screening of 35delG mutations does not replace the audiological screening tests, because the auditory function involves 1% of the human genes and mutations of any of these may lead to deafness.

scholarly journals Identification of Two Novel Compound Heterozygous PTPRQ Mutations Associated with Autosomal Recessive Hearing Loss in a Chinese Family

PLoS ONE ◽  
2015 ◽  
Vol 10 (4) ◽  
pp. e0124757 ◽  
Author(s):  
Xue Gao ◽  
Yu Su ◽  
Yu-Lan Chen ◽  
Ming-Yu Han ◽  
Yong-Yi Yuan ◽  
...  
Keyword(s):  
Hearing Loss ◽  
Autosomal Recessive ◽  
Chinese Family ◽  
Compound Heterozygous

scholarly journals Concurrent genetic and standard screening test for hearing reduction

2020 ◽  
Vol 66 (2) ◽  
pp. 35-40
Author(s):  
Marina Davcheva Chakar ◽  
Gjorgji Bozhinovski ◽  
Emilija Shukarova Stefanovska ◽  
Dejan Trajkov
Keyword(s):  
Hearing Loss ◽  
Hearing Impairment ◽  
Genetic Screening ◽  
Screening Test ◽  
Screening Program ◽  
Deaf Child ◽  
Hearing Screening ◽  
Pathogenic Variant ◽  
Gjb2 Gene ◽  
Brainstem Response

Reduction of hearing is the most common sensory impairment among newborns with an incidence of 1-3 per 1000 births. Introduction of an Auditory Newborn screening program allows early identification of hearing impairment. Mainly, congenital hearing loss in early childhood is a result of genetic changes. Due to high frequency of GJB2 pathogenic variants, its molecular characterization among sensorineural hearing reduction cases is already conducted as a routine analysis in many countries. The aim of this study is to show our initial results in the effort to determine whether genetic screening along with the standard hearing screening in newborns is justified. Otoacoustic emission (OAE) method was conducted in 223 newborns at risk of hearing impairment. Among them, 7 did not pass the test in both ears while 9 exhibited one-sided hearing loss. In all 7 children with indication of profound bilateral deafness, the diagnosis was confirmed using auditory brainstem response. Genetic screening of GJB2 gene was performed in 6 of them. Genetic analysis of GJB2 revealed homozygous state of the most common pathogenic variant 35delG in 3 (50%) of the analyzed infants. In the remaining 3 no pathogenic variant was determined. The results indicate that performing auditory OAE together with genetic screening is justified. In newborns who have not passed the hearing screening test and have profound hearing loss, without other syndrome traits, screening for mutations of GJB2 gene should be conducted. Genetic screening enables establishment of early definite diagnosis for deafness and helps in conducting adequate therapy providing timely rehabilitation and social inclusion of deaf child. Key words: hearing loss, genetic screening, auditory screening, GJB2 gene

scholarly journals Progressive Early-Onset Leukodystrophy Related to Biallelic Variants in the KARS Gene: The First Case Described in Latin America

Genes ◽  
2020 ◽  
Vol 11 (12) ◽  
pp. 1437
Author(s):  
Adriana Vargas ◽  
Jorge Rojas ◽  
Ivan Aivasovsky ◽  
Sergio Vergara ◽  
Marianna Castellanos ◽  
...  
Keyword(s):  
Hearing Loss ◽  
Gene Mutations ◽  
Mitochondrial Respiratory Chain ◽  
Trna Synthetase ◽  
Transfer Rna ◽  
Compound Heterozygous ◽  
Heterozygous State ◽  
Aminoacyl Trna Synthetase ◽  
First Case ◽  
Compound Heterozygous State

The KARS gene encodes the aminoacyl-tRNA synthetase (aaRS), which activates and joins lysine with its corresponding transfer RNA (tRNA) through the ATP-dependent aminoacylation of the amino acid. KARS gene mutations have been linked to diverse neurologic phenotypes, such as neurosensorial hearing loss, leukodystrophy, microcephaly, developmental delay or regression, peripheral neuropathy, cardiomyopathy, the impairment of the mitochondrial respiratory chain, and hyperlactatemia, among others. This article presents the case of a Colombian pediatric patient with two pathological missense variants in a compound heterozygous state in the KARS gene and, in addition to the case report, the paper reviews the literature for other cases of KARS1-associated leukodystrophy.

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