Search

Abstract: Inner ear is critical for the development of motion sickness (MS). The present work was designed to test the role of aquaporins (AQPs) in inner ear in MS. After repetitive stimulus of rotation, the MS symptom was steadily alleviated in mice. After repetitive stimulus of rotation, several AQPs mRNA levels including AQP1, AQP2, AQP3, AQP4, AQP6, AQP7, and AQP9 in the inner ears of mice were analyzed. It was found that AQP1 mRNA level was increased remarkably, which was reconfirmed by Western blotting analysis. In addition, the relationship between AQP1 expression and MS sensitivity was studied and it was shown that AQP1 mRNA level was negatively related to MS index in mice. We sought to examine the function of AQP1 in inner ear using an RNAi approach to reduce the AQP1 protein expression in vivo. It was first observed that AQP1 knockdown in inner ear resulted in a significant increase of MS sensitivity in mice. In conclusion, after repetitive stimulus of rotation, the alleviation of MS symptom in mice was, at least in part, due to the upregulation of AQP1 expression in inner ear. In addition, the sensitivity to MS in mice was, at least in part, dependent on the expression of AQP1 in inner ear. AQP1 in inner ear plays an important role in the development of MS, and might be a potential target for the prevention or management of MS. [Copyright &y& Elsevier]

Abstract Objective Hereditary nonsyndromic hearing loss is extremely heterogeneous and an X-linked form accounts for 1–5% of all cases. The aim of this study was to identify the pathogenic variants in a nonsyndromic X-linked dominant hearing loss family, and explain the reason of different hearing phenotype in hearing between the two sisters with the same variant. Methods Targeted gene capture and next-generation sequencing were used to study the genetic cause. What's more, methylation differences among the androgen receptor genes were used to investigate whether the different hearing levels of the two sisters is related to X-chromosome inactivation (Xi). Results We identified SMPX c.29insA (p.Asn10Lysfs*3) as the novel variant causing deafness. The skewed X-chromosome inactivation was relevant to the hearing difference between the two sisters. Conclusion Targeted gene capture and NGS is an efficient way to identify pathogenic variants in genes. Analysis of X-chromosome inactivation is beneficial to the diagnosis and genetic counseling of X-linked dominant hearing loss families. [ABSTRACT FROM AUTHOR]

Objectives To provide appropriate genetic testing and counseling for non-syndromic hearing impairment patients in Hainan Province, an island in the South China Sea. Methods 299 unrelated students with non-syndromic hearing loss who attended a special education school in Hainan Province were enrolled in this study. Three prominent deafness-related genes ( GJB2 , SLC26A4 , and mtDNA 12S rRNA ) were analyzed using Sanger sequencing. Results GJB2 mutations were detected in 32.78% (98/299) of the entire cohort; however, only 5.69% (17/299) had two confirmed pathogenic mutations. The most common mutation observed in this population was c.109G > A in the GJB2 gene, with an allelic frequency of 15.05% (90/598), which is significantly higher than that reported in previous cohorts. A total of 16 patients had two confirmed pathogenic SLC26A4 gene mutations, and 16 patients had one. The IVS7-2A > G mutation was the most commonly observed, with an allelic frequency of 3.51% (21/598). Three patients had a m.1555A > G mutation in the mtDNA 12S rRNA gene. Conclusions These results reveal that genetic etiology occurred in 11.71% (35/299) of patients, suggesting that Hainan province have a different mutational spectrum compare to Mainland China in non-syndromic deafness patients, which provide useful information to genetic counseling in Hainan province. [ABSTRACT FROM AUTHOR]

Background Mutations in GJB3 were originally shown to underlie an autosomal dominant form of non-syndromic deafness in Chinese patients and the c.538C>T (p.R180*) variants caused high-frequency hearing loss. But after that, few reports have reported this mutation. This study investigated the relationship between the GJB3 c.538C>T variant and hearing phenotype in Chinese to assist with risk assessment and genetic counseling for hearing loss patients and their families. Method The study enrolled 5700 patients with hearing loss and 4600 normal subjects. Deafness gene mutations were distinguished using a gene chip. The GJB3 c.538C>T variant rate was calculated from the results. Result Of the 5700 patients, 23 (0.40%) carried a GJB3 c.538C>T heterozygous variant; of these, 11 patients had other gene ( GJB2 / SLC26A4 ) mutations simultaneously. Most patients had moderate to profound hearing loss. All 23 patients were sporadic cases and had no family history of deafness. Of the 4600 normal individuals, 11 (0.24%) had GJB3 c.538C>T heterozygous variant. There was no statistical difference in incidence between the two groups. Conclusions Our results showed that the GJB3 c.538C>T variant has a very low incidence in the Chinese population, and there was no clear evidence to support a role of the GJB3 c.538C>T variant in the autosomal dominant form of non-syndromic deafness. Our findings suggested that GJB3 c.538C>T does not contribute to hearing loss, and this conclusion will assist with genetic counseling and risk prediction for deafness related to the GJB3 c.538C>T variant. [ABSTRACT FROM AUTHOR]

Background Disease-associated mutations in GJB2 gene are one of the major reasons that can cause non-syndromic sensorineural hearing loss (NSHL). GJB2 gene deafness has various clinical phenotypes. This study aims to analyze characteristics and relationships of clinical phenotypes through analyzing 1481 NSHL cases and 190 GJB2 deafness patients (with dual gene mutations). Patients and methods All the patients diagnosed as deaf disease molecular diagnostics were obtained from the people's liberation army general hospital from March 2007 to March 2011. The accession number of GJB2 was NM_004004 in GenBank, and sequence alignment and annotation were performed using GeneTool software. Results In NSHL patients, mutated allele frequency in GJB2 was 20.57%, and the preponderant type was c.235delC (11.84%) followed by c.109G>A (3.75%). Mutation rate of double allelic gene was 16.18%, including 8.43% of homozygous mutation rate and 7.75% of recombination heterozygosis mutation. Moreover, auditory threshold of GJB2 biallelic marker was associated with ages of onset, while no significant correlation was detected with disease time and whether the inner ear malformation. Similar clinical phenotype could be detected between patients with c.109G>A dual gene mutation and dual gene mutation. However, in the aspect of hearing impairment, the phenomenon of pathopoiesia caused by mutation of c.109G>A was poorer than the other mutations, and even near those patients without pathogenic mutations. Conclusion Our study further shows the definite relationship of clinical phenotype and genotype in GJB2 gene correlated deafness, and these results can provide basis for revealing pathogenesis, gene diagnosis and consult of deafness. The level of evidence in the study is level 4 (case series). [ABSTRACT FROM AUTHOR]

Background Exposure to aminoglycoside antibiotics can induce ototoxicity in genetically susceptible individuals carrying certain mitochondrial DNA (mtDNA) mutations (C1494T and A1555G), resulting in hearing loss. So, a rapid diagnostic approach is needed to accurately identify subjects carrying such gene mutations. Methods In the present study, we describe a rapid and reliable four-color, real-time quantitative polymerase chain reaction (qPCR) assay for simultaneously detecting two mtDNA 12S rRNA gene variants, A1555G and C1494T, which are prevalent in the Han Chinese population. This multiplex assay incorporates three allele-specific TaqMan probes labeled with different fluorophores in a single reaction, providing high genotyping accuracy for clinical blood samples. Results Tests with C1494T, A1555G and wild-type DNA exhibited high sensitivity, specificity, reproducibility and accuracy of discriminating mutations from wild-type. Conclusions This study shows that this simple and inexpensive method can be used for routine molecular diagnostics and potentially for large-scale genetic screening. [ABSTRACT FROM AUTHOR]

IFNLR1 has been recently identified to be related to autosomal dominant nonsyndromic sensorineural hearing loss (ADNSHL). It is reported to be expressed in the inner ear of mice and the lateral line of zebrafish. However, it remains unclear how defects in this gene lead to hearing loss. To elucidate the global gene expression changes in zebrafish when the expression of ifnlr1 is downregulated. Transcriptome analysis was performed on ifnlr1 morpholino knockdown zebrafish and the control zebrafish using RNA-seq technology. The results show that 262 differentially expressed genes (DEGs) were up-regulated while 146 DEGs were down-regulated in the E4I4–Mo zebrafish larvae compared to the control-Mo. Six pathways were significantly enriched, including steroid biosynthesis pathway, adipocytokine signaling pathway, cytokine-cytokine receptor interaction pathway, p53 signaling pathway, AGE-RAGE signaling pathway in diabetic complications, and terpenoid backbone biosynthesis pathway. Among them, three pathways (steroid biosynthesis pathway, cytokine-cytokine receptor interaction pathway and p53 signaling pathway) are immune-associated. The transcriptome analysis results contribute to the groundwork for future research on the pathogenesis of IFNLR1 -associated hearing loss. [ABSTRACT FROM AUTHOR]

Hereditary hearing loss is a common defect of the auditory nervous system with high-incidence, seriously affecting the quality of life of the patients. The clinical manifestations of SLC26A4 mutation-related hearing loss are congenital sensorineural or mixed deafness. Sensitive and specific SLC26A4 mutation detection in the early clinical stage is key for the early indication of potential hearing loss in the lack of effective treatment. Using clustered regularly interspaced short palindromic repeats (CRISPR)-based nucleic acid detection technology, we designed a fast and sensitive detection system for SLC26A4 pathogenic mutations (c.919-2A > G, c.2168A > G and c.1229C > T). This recombinase-aided amplification-based detection system allows rapid target gene amplification and, in combination with the CRISPR-based nucleic acid testing (NAT) system, mutation site detection. Moreover, mismatches were introduced in CRISPR-derived RNA (crRNA) to increase signal differences between the wild-type genes and mutant genes. A total of 64 samples were examined using this approach and all results were verified using Sanger sequencing. The detection results were consistent with the polymerase chain reaction-Sanger sequencing results. Overall, this CRISPR-based NAT technology provides a sensitive and fast new approach for the detection of hereditary deafness and provides a crRNA optimization strategy for single-nucleotide polymorphism detection, which could be helpful for the clinical diagnosis of SLC26A4 mutation-related hereditary hearing loss. [ABSTRACT FROM AUTHOR]

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]

Abstract: In most studies, sensorineural hearing loss is reported as a single-gene disease with autosomal dominant or autosomal recessive or with X-linked or maternal inheritance. It is uncommon that the hearing impairment is caused by a combined inheritance model including genomic and mitochondrial models. Here, we report six patients with sensorineural hearing loss caused by co-existing mutations in GJB2 or SLC26A4 and the mitochondrial gene. And there was no significant difference in hearing phenotypes between the six patients and the controls. The results indicate the complicated genetic etiology of, and may impact the diagnostic strategy for, hereditary hearing impairment. All patient siblings will carry mitochondrial DNA A1555G or C1494T mutations, and 25% of siblings may carry the same homozygous or compound heterozygote mutations in GJB2 or SLC26A4. Although this combined inheritance is not common in the Chinese deaf population (0.10%), our findings will have great impact in genetic counseling and risk prediction for deafness. [Copyright &y& Elsevier]

Abstract: Background: Most studies of the molecular etiology of sensorineural hearing loss have described deafness as a monogenic disease encompassing double-allele mutations for patients with autosomal recessive deafness. Here, we report the first case of autosomal recessive genetic deafness in an enlarged vestibular aqueduct syndrome (EVAS) patient with biallelic mutations in two deafness genes. Methods: Temporal computed tomography (CT), complete physical and otoscopic examinations, and an audiological study, including tympanometry, pure-tone audiometry or auditory steady-state response (ASSR), were carried out. Exon 2 of GJB2 and the coding exons of SLC26A4 were sequenced. Results: A patient with an enlarged vestibular aqueduct was found to carry c.1229C>T/c.1079C>T compound heterozygous mutations in SLC26A4.This individual also carried c.257C>G/c.299-300delAT compound heterozygous mutations in GJB2. As a result, the recurrent risk of the patient''s siblings increased significantly from 25% for typical autosomal recessive deafness to 43.75%. Conclusions: The findings of the present study challenge the traditional diagnostic strategy in which testing is generally considered complete upon identification of a double-allele mutation within one gene, with significant implications for genetic counseling and risk prediction. Our results suggest that, with advances in sequencing technology, it will be possible and necessary to test all known deafness genes in the near future, as this will likely allow more accurate genetic counseling of patients. [Copyright &y& Elsevier]

Abstract: Background: Mutations in the GJB2 gene are the most common cause of nonsyndromic autosomal recessive sensorineural hearing loss. A few mutations in GJB2 have also been reported to cause dominant nonsyndromic or syndromic hearing loss. However, de novo or dominant mutation in GJB2 is not common in Chinese populations. Methods: Two probands with hearing impairment from unrelated Chinese families are reported here. Temporal CT scan, complete physical (including skin and hair) and otoscopic examinations, and an audiological study, including tympanometry, auditory brainstem response (ABR), auditory steady-state response (ASSR), and 40Hz-auditory event-related potential (40Hz-AERP), were carried out. The two exons of GJB2, the coding exons of SLC26A4, and mitochondrial 12S rRNA were sequenced. Results: Sequencing of GJB2 in the two cases showed a heterozygous c.551G>A(p.R184Q) mutation, which was not found in other family members. Additionally, no other mutation in GJB2 was identified in the two family members. Paternity was confirmed by genotype analysis of 15 informative short tandem repeats (STRs) from the chromosomes. Sequence analysis of the coding exons of SLC26A4 and mitochondrial 12S rRNA was performed but no sequence aberration or deletion was found. Conclusions: A de novo GJB2 p.R184Q mutation can cause severe-to-profound bilateral sensorineural hearing impairment. Although not common in Chinese patients with hearing loss, it is important to identify the specific phenotype and genotype correlations of the de novo dominant mutation in GJB2. [Copyright &y& Elsevier]

Abstract: We have established a mobile phone-assisted microarray decoding platform for signal-enhanced mutation detection. A large amount of single-stranded DNA (ssDNA) was obtained by combining symmetric PCR and magnetic isolation, and ssDNA prepared with magnetic bead as label was further allowed to hybridize against the tag-array for decoding purpose. High sensitivity and specificity was achieved with the detection of genomic DNA. When simultaneously genotyping nine common mutations associated with hereditary hearing loss, the detection limit of 1ng genomic DNA was achieved. Significantly, a mobile phone was also used to record and decode the genotyping results through a custom-designed imaging adaptor and a dedicated mobile phone software. A total of 51 buccal swabs from patients probably with deafness-related mutations were collected and analyzed. The genotyping results were all confirmed by fluorescence-based laser confocal scanning and direct DNA sequencing. This mobile phone-assisted decoding platform provides an effective but economic mutation detection alternative for the future quicker and sensitive detection of virtually any mutation-related diseases in developing and underdeveloped countries. [Copyright &y& Elsevier]

Abstract: Mutations in mitochondrial DNA (mtDNA) are associated with sensorineural hearing loss. In this study, we traced the origin of the 12S rRNA C1494T mutation through analysis of the clinical, genetic, and molecular characteristics of 13 Han Chinese pedigrees with aminoglycoside-induced and non-syndromic bilateral hearing loss that were selected by C1494T screening in 3133 subjects with non-syndromic hearing impairment from 27 regions of China (13/3133). Clinical evaluation revealed the variable phenotypes of hearing impairment including severity, age-of-onset, and audiometric configuration in these subjects. Through the whole mitochondrial genome DNA sequence analysis, we identified two evolutionarily conservative variants in protein-coding genes: tRNAAla T 5628C and tRNATyr A5836G mutations. However, the pedigrees with these mutations did not have a higher or lower penetrance of deafness than in other pedigrees. These results suggested that both T 5628C and A5836G mutations might not significantly modify the manifestation of the C1494T mutation. Sequencing analysis of the whole mitochondrial genome of the probands showed that 13 pedigrees from seven different provinces were classified into 10 haplogroups by the distinct sets of mtDNA polymorphisms, including haplogroups A, B, D, D4, D4b2, F1, M, M7c, N9a1, and H2b. This result suggested that the C1494T mutation occurred sporadically with multi-origins through the evolution of the mtDNA in China, and these mtDNA haplogroup-specific variants may not play an important role in the phenotypic expression of the C1494T mutation in these Chinese families with different penetrance of hearing loss. In addition, the lack of a significant mutation in the GJB2 gene ruled out the possible involvement of GJB2 in the phenotypic expression of the C1494T mutation in those affected subjects. Therefore, the aminoglycosides is solo well-established factor to contribute to the deafness manifestation of the C1494T mutation, and prevention by avoiding the administration of aminoglycosides in individuals carrying C1494T mutation is the most effective way to protect their vulnerability to deafness. [Copyright &y& Elsevier]

Abstract: We report here the clinical, genetic and molecular characterization of three Chinese pedigrees with nonsyndromic bilateral hearing loss. Clinical and genetic evaluations revealed the variable severity and age-of-onset in hearing impairment in these families. Strikingly, there were extremely low penetrances of hearing impairment in these Chinese families. Sequence analysis of the complete mitochondrial DNA (mtDNA) showed the known A7445C mutation in two pedigrees and the novel A7445T mutation in another pedigree, in addition to distinct sets of mtDNA polymorphisms belong to Asian haplogroups D4j and F4. Indeed, the A7445C or A7445T mutation in the CO1 and the precursor of tRNASer(UCN) genes was present in homoplasmy only in the maternal lineage of those pedigrees but not other members of these families and 164 Chinese controls. In fact, the A7445C or A7445T mutation results in a read-through of the stop condon AGA of the CO1 message on the H strand of mtDNA, thereby adding three amino acids (Ser-Gln-Lys) to the C-terminal of the polypeptide. However, the mutated polypeptide may retain a partial function. Alternatively, the A7445C or A7445T mutation is adjacent to the site of 3′ end endonucleolytic processing of L-strand RNA precursor, spanning tRNASer(UCN) and ND6 mRNA. Thus, the A7445C or A7445T mutation may also cause a defect in the processing of the L-strand RNA precursor, thus causing mitochondrial dysfunctions. Furthermore, the occurrence of the mutations at position 7445 in these genetically unrelated subjects affected by hearing impairment strongly indicates that mutations at the position 7445 are involved in the pathogenesis of hearing impairment. [Copyright &y& Elsevier]