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Porokeratotic eccrine ostial and dermal duct nevus or porokeratotic eccrine nevus (PEN) is a rare nevoid condition characterized by asymptomatic spiny, keratotic papules, and plaques in linear distribution along Blaschko's lines on the extremities clinically and discrete vertical cornoid lamellae at eccrine ostia pathologically. Keratitis–ichthyosis–deafness (KID) syndrome manifests generalized erythematous plaques with tiny papules and keratotic spicules. Both rare diseases are associated with mutations of the GJB2 gene encoding for gap junction protein, connexin 26. We present a case of KID syndrome in an 11-year-old boy. The patient presented with bilateral hearing loss, and large erythematous plaques with grained leather-like appearance and occasional keratotic spicules on the face and trunk as well as prominent hyperkeratosis on the acral parts, especially distal digits. Skin biopsy of two skin lesions revealed features of PEN. Mutation analysis of peripheral blood revealed GJB2 c. 263C>T (p.A88V). This is the first report of GJB2 gene mutation in a Taiwanese boy with KID syndrome. The histologic features of PEN in the present case provide additional support that PEN may be part of the manifestation of KID syndrome.

Mutations in GJB2 encoding Connexin 26 (CX26) are associated with hearing loss and hyperproliferative skin disorders of differing severity including keratitis‐ichthyosis‐deafness (KID) and Vohwinkel syndrome. A 6‐year‐old Caucasian girl who presented with recurrent skin rashes and sensorineural hearing loss harboured a heterozygous point mutation in GJB2 (c.424T > C; p.F142L). To characterize the impact of CX26F142L on cellular events. Plasmids CX26WT, CX26F142L, CX26G12R (KID) or CX26D66H (Vohwinkel) were transfected into HeLa cells expressing Cx26 or Cx43 or into HaCaT cells, a model keratinocyte cell line. Confocal microscopy determined protein localization. MTT assays assessed cell viability in the presence or absence of carbenoxolone, a connexin‐channel blocker. Co‐immunoprecipitation/Western blot analysis determined Cx43:Cx26 interactions. Quantitative real‐time polymerase chain reaction assessed changes in gene expression of ER stress markers. Dye uptake assays determined Connexin‐channel functionality. F142L and G12R were restricted to perinuclear areas. Collapse of the microtubule network, rescued by co‐treatment with paclitaxel, occurred. ER stress was not involved. Cell viability was reduced in cells expressing F142L and G12R but not D66H. Unlike G12R that forms "leaky" hemichannels, F142L had restricted permeability. Cell viability of F142L and G12R transfected cells was greater in HeLa cells expressing Cx43 than in native Cx‐free HeLa cells. Co‐immunoprecipitation suggested a possible interaction between Cx43 and the three mutations. Expression of CX26F142L and G12R results in microtubule collapse, rescued by interaction with Cx43. The GJB2 mutations interacted with Cx43 suggesting that unique Cx43:Cx26 channels are central to the diverse phenotype of CX26 skin‐related channelopathies. [ABSTRACT FROM AUTHOR]

Introduction. At the moment there is not enough data in Romania about the incidence of the main genetic mutations which can cause hearing loss.

Abstract Background In the present study, we investigate the prevalence of the GJB2 gene mutations, and deletions in the GJB6 gene, namely del (GJB6‐D13S1830) and del (GJB6‐D13S1854), in patients with autosomal recessive non‐syndromic hearing loss (ARNSHL) from the central region of Iran. Methods One hundred and thirty‐one unrelated ARNSHL cases from the central part of Iran were recruited. Among them, 81% (106 cases) had at least two affected relatives. Coding and noncoding regions of the GJB2 gene were sequenced. Multiplex PCR was used for analysis of del (GJB6‐D13S1830) and del (GJB6‐D13S1854) deletions in GJB6. Results The GJB2 variants were found in 16.79% (22/131) of the patients. The pathogenic variants were 21/131 (16.03%). The nonpathogenic variants were 1/131 (0. 07%). Allele frequency of the c.35delG as the pathogenic variant was the most common with 59.52% (25/42). The remaining pathogenic variants were c.235delC, p.T8M, p.R32H, p.R143Q, p.R143W, c‐23+1G>A. The only nonpathogenic variant was polymorphism p.V27I. Further segregation analysis showed that variant of p.R143Q might have incomplete penetrance. None of the patients had targeted deletions in the GJB6 gene. Conclusion In comparison with reports from other areas of Iran, c.35delG demonstrates the highest frequency within the central region (accounting for 57.14% of cases), probably resulting from the founder effect and consanguineous marriage. The pathology of ARNSHL in such patients could be attributed to defects in Connexin 26 encoded by GJB2.

Mutations in the Gjb2 gene, which encodes a gap junction protein connexin26 (Cx26), are the most prevalent form of hereditary deafness in humans and represent about half of non-syndromic congenital deafness cases in many ethnic populations. Cochlear potassium (K+) recycling in mature cochlea is required for normal hearing. It is thought that gap junctions are essential for K+ recycling and that Gjb2 mutations cause Gjb2-associated deafness by disrupting K+ recycling in mature cochlea. Here we present evidence showing that Gjb2 is required for normal development of the neonatal organ of Corti prior to the onset of the hearing in mice. In the conditional Gjb2 null (cCx26 null) mice, ribbon synapses in inner hair cells remained poorly developed, the afferent type I fibers failed to finish the refinement process to form convergent innervation to individual inner hair cells. The spontaneous depolarizing activities in the supporting cells, which normally diminish in the wild type cochleae after postnatal day 8 (P8), remained strong in the cochlea after P8 in the mutant mice. Furthermore, the deafness phenotype was readily generated only if the Cx26 expression in the organ of Corti was significantly reduced before P6. Similar amount of Cx26 reduction in more mature cochleae had a much weaker effect in damaging the hearing sensitivity. Our findings indicated that Cx26 plays essential roles in the maturation process of the organ of Corti prior to the establishment of high K+ in the endolymph and the onset of hearing. These results suggest that successful treatment of Cx26 deafness requires early intervention before the cochlea fully matures.

Purpose: Pathogenic variants of the gap junction beta 2 (GJB2) gene are responsible for about 50% of hereditary non-syndromic sensorineural hearing loss (NSHL). In this study, we report mutation frequency and phenotype comparison of different GJB2 gene alterations in Hungarian NSHL patients.Methods: The total coding region of the GJB2 gene was analyzed with Sanger or NGS sequencing for 239 patients with NSHL and 160 controls.Results: Homozygous and compound heterozygous GJB2 mutations were associated with early onset serious clinical phenotype in 28 patients. In 24 patients, two deletion or nonsense mutations were detected in individuals with mainly prelingual NSHL. In compound heterozygous cases, a combination of deletion and missense mutations associated with milder postlingual NSHL. A further 25 cases harbored single heterozygous GJB2 mutations mainly associated with later onset, milder clinical phenotype. The most common mutation was the c.35delG deletion, with 12.6% allele frequency. The hearing loss was more severe in the prelingual groups.Conclusion: The mutation frequency of GJB2 in the investigated cohort is lower than in other European cohorts. The most serious cases were associated with homozygous and compound heterozygous mutations. In our cohort the hearing impairment and age of onset was not altered between in cases with only one heterozygous GJB2 mutation and wild type genotype, which may exclude the possibility of autosomal dominant inheritance. In early onset, severe to profound hearing loss cases, if the GJB2 analysis results in only one heterozygous alteration further next generation sequencing is highly recommended. [ABSTRACT FROM AUTHOR]

Porokeratotic eccrine ostial and dermal duct nevus or porokeratotic eccrine nevus (PEN) is a rare nevoid condition characterized by asymptomatic spiny, keratotic papules, and plaques in linear distribution along Blaschko's lines on the extremities clinically and discrete vertical cornoid lamellae at eccrine ostia pathologically. Keratitis–ichthyosis–deafness (KID) syndrome manifests generalized erythematous plaques with tiny papules and keratotic spicules. Both rare diseases are associated with mutations of the GJB2 gene encoding for gap junction protein, connexin 26. We present a case of KID syndrome in an 11-year-old boy. The patient presented with bilateral hearing loss, and large erythematous plaques with grained leather-like appearance and occasional keratotic spicules on the face and trunk as well as prominent hyperkeratosis on the acral parts, especially distal digits. Skin biopsy of two skin lesions revealed features of PEN. Mutation analysis of peripheral blood revealed GJB2 c. 263C>T (p.A88V). This is the first report of GJB2 gene mutation in a Taiwanese boy with KID syndrome. The histologic features of PEN in the present case provide additional support that PEN may be part of the manifestation of KID syndrome. [ABSTRACT FROM AUTHOR]

Introduction: Audiological performance in cochlear implanted children may vary depending of the etiology of the deafness, one of which is GJB2 gene mutations. Aim: In this study we evaluated the auditory performance by pure tone audiogram testing after unilateral cochlear implantation for children with GJB2 related mutations and to compare the results with the ones from children that did not show any mutations in the GJB2 gene. Material and Methods: We have determined the auditory tonal thresholds in 28 patients and we calculated the average of these thresholds for the frequencies of 500, 1000, 2000 and 4000Hz. We have taken into consideration the first tonal thresholds that averaged at 35dB or better for the given frequencies. Results and Discussions: Comparison between the average tonal thresholds between the two groups show that even though children from the GJB2 mutation related deafness group need a slightly longer period of time to reach minimal conversational level thresholds, the dB value of these levels is lower than the ones in the second group. Conclusions: This can prove to be a useful tool for the clinician regarding cochlear implant counselling and for the patient in terms of better speech understanding skills and oral communication with parents and educational staff.

Abstract: Objective: To assess the molecular etiology of nonsyndromic sensorineural hearing loss (NSHL) in members of an affected Chinese family. Methods: Common hearing-related genes including gap junction beta 2 (GJB2), SLC26A4, mitochondrial DNA 12S rRNA, GJB3 and GJB6 were examined in a family consisting of a normal hearing father, an NSHL-affected mother, one normal-hearing child and three NSHL-affected children. Specific primers were used in polymerase chain reactions to amplify the coding regions of the above genes from the peripheral blood DNA from each family member, and the genes were analyzed by direct sequencing. The subjects were evaluated for phenotypic characterization using audiometric testing and radiological examination of the inner ear. Results: Pathogenic mutations in the GJB2 gene were identified. The affected mother showed a heterozygous G→A transition at nucleotide 232, resulting in an alanine to threonine substitution at codon 78 (p.A78T), and the normal hearing father had a c.35insG insertion mutation. The three affected children displayed heterozygosity for the GJB2 mutations, showing a previously unreported combination of c.35insG and c.232G>A. Conclusions: The GJB2 mutations account for a significant proportion of NSHL in affected individuals worldwide. Genetic and audiological data analysis of a Chinese family with NSHL revealed a novel c.35insG/c.232G>A compound heterozygous state. Our results highlight the complexity of the GJB2 genotypes and phenotypes. [Copyright &y& Elsevier]

Conclusions: Outcomes following cochlear implantation in children with congenital cytomegalovirus (CMV) infection were almost equivalent to those of children with GJB2 mutation-related sensorineural hearing loss (SNHL). Although our patients with developmental disorder showed poor auditory performance and speech and language skills after cochlear implantation, SNHL with developmental disorder should not be a contraindication for the procedure. Objective: Congenital CMV infection accounts for approximately 20% of all cases of neonatal hearing loss, while the GJB2 mutation accounts for 30-50% of all cases of profound nonsyndromic hearing loss. Here, outcomes for auditory behavior and speech and language skills were compared in children with congenital CMV infection or GJB2 mutation who received cochlear implantation for profound SNHL. Methods: Five children with asymptomatic congenital CMV infection and seven children with GJB2 mutation-related SNHL, with and without developmental disorder, underwent cochlear implantation. Hearing level and speech and language development were evaluated post-implantation using IT-MAIS, MUSS, and S-S method. Results: The IT-MAIS and MUSS scores of the congenital CMV infection group and the GJB2 mutation group continued to increase for 4 years after implantation. The S-S method score in both groups gradually increased, although the scores for children with mental retardation were low. [ABSTRACT FROM AUTHOR]

Abstract: Objective: This study aimed to investigate the prevalence of GJB2 gene for the 235delC mutations, the clinical features and the outcomes of patients who had undergone cochlear implantation. Methods: We have sequenced the coding region of GJB2 gene for 135 patients with sensorineural deaf from September 2000 to May 2009. Of the 135 patients, the patients with the homozygous 235delC and the compound-heterozygous Y136X/G45E were detected and were investigated clinically. Results: The GJB2 gene for the 235delC mutations was found in 39 alleles of 270 alleles (14.4%), especially for the homozygous of 235delC was detected in 26 alleles (9.6%), the single heterozygous of 235delC was 1 allele (0.4%), the compound heterozygous of 235delC was found in 12 alleles (4.4%). Of 16 subjects (29 alleles) with the homozygous 235delC and the compound-heterozygous Y136X/G45E, 2 subjects (4 alleles) were found to have complications. All of the subjects were found to show severe hearing loss and some of them have indicated progressive hearing loss. However, they showed better performance regarding the thresholds after implantation. The subjects with complications, although, suggested poorer performance in the auditory speech performance. Conclusion: The findings of poorer outcomes might depend on complications and brain functions. In addition, considering the blood test parameters, an independent elevated LDH and ChE at diagnosis were found to be associated with hereditary enzyme''s metabolic disease. Therefore, the value of LDH measurements in patients might be a helpful predictive parameter in hereditary diseases. [Copyright &y& Elsevier]

Objectives/Hypothesis: Connexin 26 is a gap junction protein encoded by the GJB2 gene. It is expressed in cholesteatoma, and mutations cause proliferative skin disorders and sensorineural hearing loss (SNHL). Deletions of GJB6, which encodes connexin 30, cause SNHL in a digenic manner with a heterozygous GJB2 mutation. We hypothesize that GJB2 and GJB6 mutations might influence the development of cholesteatoma. Study Design: Prospective observational study to identify GJB mutations in pediatric cholesteatoma. Methods: Peripheral blood samples from 98 children with cholesteatoma were screened for mutations in the GJB2 gene by direct sequencing of the coding region (exon 2 and the intron/exon boundary). Deletions of the GJB6 gene were tested using multiple ligation probe amplification methods. GJB status was compared with other populations and patient age and extent of cholesteatoma at presentation. Results: Fourteen children had at least one GJB2 variant (14%). Of these, three had two variants. Two of the variants were neutral polymorphisms. One child with the GJB2 genotype 35delG/35delG also had SNHL. No correlation was found between GJB2 status and patient age or cholesteatoma severity at presentation. No GJB6 deletions were found. Conclusions: GJB2 gene variants are present in a minority of children with cholesteatoma, but may be more common than in normal populations. It is conceivable that alterations of connexin 26 expression could contribute to the multifactorial disease process in cholesteatoma by modifying the cell-to-cell communication that is important in proliferation and migration of keratinocytes. Laryngoscope, 2010 [ABSTRACT FROM AUTHOR]

Mutations of the GJB2 gene, encoding Connexin 26, are the most common cause of hereditary congenital hearing loss in many countries, and account for up to 50% of cases of autosomal-recessive non-syndromic deafness. By contrast, only a few GJB2 mutations have been reported to cause an autosomal-dominant form of non-syndromic deafness. We report on a family from southern Italy in whom dominant, non-syndromic, post-lingual hearing loss is associated with a novel missense mutation in the GJB2 gene. Direct sequencing of the gene showed a heterozygous G→A transition at nucleotide 535, resulting in an aspartic acid to asparagine amino acid substitution at codon 179 (D179N). This mutation occurred in the second extracellular domain (EC2), which would seem to be very important for connexon–connexon interaction. [ABSTRACT FROM AUTHOR]

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In the present article we report cytomegalovirus (CMV) DNA localization in the inner ear of a 15-month-old deaf boy 1 month after a virologically documented primary infection. CMV DNA retrieval was possible thanks to polymerase chain reaction analysis of the perilymph collected at cochlear implant surgery. To the authors' knowledge this is the first demonstration of CMV persistence in the cochlea of an immunocompetent subject after an acquired infection. Laryngoscope, 2011 [ABSTRACT FROM AUTHOR]

The present study describes the audiological profile of genetic hearing loss resulting from GJB2 mutations in northern Greece, as this represents the most frequent single cause of childhood sensorineural hearing loss. The 35delG mutation in homozygosity was detected in 27 of 107 patients (25.2%). The audiological profile is that of a profound or severe sensorineural hearing loss, with a sloping or flat configuration of the audiogram, mostly symmetrical, non-progressive and affecting more the higher frequencies. This profile underlines the importance of early identification and genetic family counseling leading to the future possibility of prevention of deafness. [ABSTRACT FROM AUTHOR]

Background: In the present study, we investigate the prevalence of the GJB2 gene mutations, and deletions in the GJB6 gene, namely del (GJB6‐D13S1830) and del (GJB6‐D13S1854), in patients with autosomal recessive non‐syndromic hearing loss (ARNSHL) from the central region of Iran. Methods: One hundred and thirty‐one unrelated ARNSHL cases from the central part of Iran were recruited. Among them, 81% (106 cases) had at least two affected relatives. Coding and noncoding regions of the GJB2 gene were sequenced. Multiplex PCR was used for analysis of del (GJB6‐D13S1830) and del (GJB6‐D13S1854) deletions in GJB6. Results: The GJB2 variants were found in 16.79% (22/131) of the patients. The pathogenic variants were 21/131 (16.03%). The nonpathogenic variants were 1/131 (0. 07%). Allele frequency of the c.35delG as the pathogenic variant was the most common with 59.52% (25/42). The remaining pathogenic variants were c.235delC, p.T8M, p.R32H, p.R143Q, p.R143W, c‐23+1G>A. The only nonpathogenic variant was polymorphism p.V27I. Further segregation analysis showed that variant of p.R143Q might have incomplete penetrance. None of the patients had targeted deletions in the GJB6 gene. Conclusion: In comparison with reports from other areas of Iran, c.35delG demonstrates the highest frequency within the central region (accounting for 57.14% of cases), probably resulting from the founder effect and consanguineous marriage. The pathology of ARNSHL in such patients could be attributed to defects in Connexin 26 encoded by GJB2. [ABSTRACT FROM AUTHOR]

Introduction: Several studies have associated congenital sensorineural hearing loss in children with prolongation of the cardiac parameter QTc. The cause of this association is unknown. At the same time, mutations in GJB2, which encodes connexin 26, are the most common cause of congenital hearing impairment., Objective: To compare electrocardiographic parameters (PR interval, QRS complex, and QTc interval) in patients with hearing loss who were tested for mutations in GJB2 and GJB6 to investigate whether these mutations affect electrical activity of the heart., Methods: 346 patients (176 males, 170 females) with sensorineural hearing loss of 30dB HL or more, aged 21.8±19.9 years (including 147 children <14 years), underwent both genetic study for GJB2 and GJB6 mutations and electrocardiography., Results: Mutations in GJB2, including homozygotes and heterozygotes, were found in 112 (32%) patients. There were no significant differences in ECG parameters between groups of patients with and without mutations in GJB2. No differences were observed either in men (mean PR with mutation: 155±16.6 vs. 153.6±30.1 without; QRS: 99.9±9.9 vs. 101.1±15.4; QTc: 414.9±29.9 vs. 412.4±25.7) or women (mean PR with: 148.7±21 vs. 143.8±22.8 without; QRS: 94.8±7.6 vs. 92.9±9.6; QTc: 416.8±20.6 vs. 424.9±22.8). In similar fashion, we did we find any significant differences between groups of children with and without GJB2 mutations (mean PR with: 126.3±19.6 vs. 127±19.7 without; QRS: 80.7±9.5 vs. 79.4±11.6; QTc: 419.7±23.5 vs. 419.8±24.8)., Conclusion: No association was found between the presence of GJB2 mutations encoding connexin 26 in patients with hearing loss and their ECG parameters (PR, QRS, QTc)., (Copyright © 2017 Associação Brasileira de Otorrinolaringologia e Cirurgia Cérvico-Facial. Published by Elsevier Editora Ltda. All rights reserved.)

Mutations in the Gjb2 gene, which encodes a gap junction protein connexin26 (Cx26), are the most prevalent form of hereditary deafness in humans and represent about half of non-syndromic congenital deafness cases in many ethnic populations. Cochlear potassium (K+) recycling in mature cochlea is required for normal hearing. It is thought that gap junctions are essential for K+ recycling and that Gjb2 mutations cause Gjb2-associated deafness by disrupting K+ recycling in mature cochlea. Here we present evidence showing that Gjb2 is required for normal development of the neonatal organ of Corti prior to the onset of the hearing in mice. In the conditional Gjb2 null (cCx26 null) mice, ribbon synapses in inner hair cells remained poorly developed, the afferent type I fibers failed to finish the refinement process to form convergent innervation to individual inner hair cells. The spontaneous depolarizing activities in the supporting cells, which normally diminish in the wild type cochleae after postnatal day 8 (P8), remained strong in the cochlea after P8 in the mutant mice. Furthermore, the deafness phenotype was readily generated only if the Cx26 expression in the organ of Corti was significantly reduced before P6. Similar amount of Cx26 reduction in more mature cochleae had a much weaker effect in damaging the hearing sensitivity. Our findings indicated that Cx26 plays essential roles in the maturation process of the organ of Corti prior to the establishment of high K+ in the endolymph and the onset of hearing. These results suggest that successful treatment of Cx26 deafness requires early intervention before the cochlea fully matures., (Copyright © 2015 Elsevier Inc. All rights reserved.)