Diagnostic Value of SLC26A4 Mutation Status in Hereditary Hearing Loss With EVA: A PRISMA-Compliant Meta-Analysis.

Many SLC26A4 mutations have been identified in patients with nonsyndromic enlarged vestibular aqueduct (EVA). However, the roles of SLC26A4 genotypes and phenotypes in hereditary deafness remain unexplained. This study aims to perform a meta-analysis based on the PRISMA statement to evaluate the diagnostic value of SLC26A4 mutant alleles and their correlations with multiethnic hearing phenotypes in EVA patients. The systematic literature search of the PubMed, Wiley Online Library, EMBASE, Web of Science, and Science Direct databases was conducted in English for articles published before July 15, 2015. Two investigators independently reviewed retrieved literature and evaluated eligibility. Discrepancy was resolved by discussion and a third investigator. Quality of included studies was evaluated using Newcastle-Ottawa Quality Assessment Scale. Data were synthesized using random-effect or fixed-effect models. The effect sizes were estimated by measuring odds ratios (ORs) with 95% confidence interval (CI). Twenty-five eligible studies involved 2294 cases with EVA data. A total of 272 SLC26A4 variations were found in deafness with EVA and 26 mutations of SCL26A4 had higher frequency. The overall OR was 646.71 (95% CI: 383.30-1091.15, P = 0.000). A total of 22 mutants were considered statistically significant in all ethnicities (ORs >1, P < 0.05). In particular, 8 mutants were specificity of EVA phenotypes in mutations of SLC26A4 for Asia deafness populations (ORs >1, P < 0.05), 4 mutants for Europe and North America (ORs >1, P < 0.05), and the IVS7-2A>G mutations in SLC26A4 were found to have the highest frequency in deafness individuals with EVA phenotype (62.42%). Moreover, subgroups for studies limited to cases with EVA phenotype, 11 mutants relevant risks (RRs) were P < 0.05, especially for IVS7-2A>G bi-allelic mutants assayed in a deafness population (RR = 0.880, P = 0.000). Diagnostic accuracy of SLC26A4 mutation results also identified the significant association of IVS7-2A>G (AUC = 0.99, 95% CI: 0.97-0.99) and p.H723R (AUC = 0.99, 95% CI: 0.98-1.00) detecting deafness with EVA. To conclude, the IVS7-2A>G and H723R in SLC26A4 present a significant predicting value and discriminatory ability for clinical use on diagnosis of EVA within a deafness population.

IVS8+1 DelG, a Novel Splice Site Mutation Causing DFNA5 Deafness in a Chinese Family.

BACKGROUND: Nonsyndromic hearing loss (NSHL) is highly heterogeneous, in which more than 90 causative genes have currently been identified. DFNA5 is one of the deafness genes that known to cause autosomal dominant NSHL. Until date, only five DFNA5 mutations have been described in eight families worldwide. In this study, we reported the identification of a novel pathogenic mutation causing DFNA5 deafness in a five-generation Chinese family. METHODS: After detailed clinical evaluations of this family, the genomic DNA of three affected individuals was selected for targeted exome sequencing of 101 known deafness genes, as well as mitochondrial DNA and microRNA regions. Co-segregation analysis between the hearing loss and the candidate variant was confirmed in available family members by direct polymerase chain reaction (PCR)-Sanger sequencing. Real-time PCR (RT-PCR) was performed to investigate the potential effect of the pathogenic mutation on messenger RNA splicing. RESULTS: Clinical evaluations revealed a similar deafness phenotype in this family to that of previously reported DFNA5 families with autosomal dominant, late-onset hearing loss. Molecular analysis identified a novel splice site mutation in DFNA5 intron 8 (IVS8+1 delG). The mutation segregated with the hearing loss of the family and was absent in 120 unrelated control DNA samples of Chinese origin. RT-PCR showed skipping of exon 8 in the mutant transcript. CONCLUSIONS: We identified a novel DFNA5 mutation IVS8+1 delG in a Chinese family which led to skipping of exon 8. This is the sixth DFNA5 mutation relates to hearing loss and the second one in DFNA5 intron 8. Our findings provide further support to the hypothesis that the DFNA5-associated hearing loss represents a mechanism of gain-of-function.

Applied anatomy of the submental island flap and its clinical application in the repair of defects following hypopharyngeal carcinoma resection.

OBJECTIVE: To explore the feasibility of the submental island flap in the repair of hypopharyngeal defects. METHODS: We collected wet specimens of fresh cadaveric heads from the Han Chinese adult population for applied anatomy of the submental island flap, and followed five patients with pyriform sinus carcinoma after reconstruction surgery using submental island flaps. RESULTS: We found that the average length and width of the submental island flaps were (65.20 ± 11.69) mm and (46.70 ± 6.59) mm, respectively. The skin flap in all five patients survived after surgery, and tracheal tubes and gastric tubes were removed 7-36 days after surgery. Patients were followed up for 24-42 months, pharyngeal flaps grew well, and speech and swallowing functions were satisfactory. CONCLUSION: The submental island flap is a preferred material for the repair of hypopharyngeal defects after hypopharyngeal carcinoma resection, because of good blood supply, easy harvesting, and high survival rate.

Understanding of the molecular evolution of deafness-associated pathogenic mutations of connexin 26.

Connexins (Cxs) were first identified as subunit proteins of the intercellular membrane channels that cluster in the cell communication structures known as gap junctions. Mutations in the gap junction ß2 (GJB2) gene encoding connexin 26 (Cx26) have been linked to sporadic and hereditary hearing loss. In some cases, the mechanisms through which these mutations lead to hearing loss have been partly elucidated using cell culture systems and animal models. The goal of this study was to re-assess the pathogenic roles of the GJB2 mutations by combining comparative evolutionary studies. We used Bayesian phylogenetic analyses to determine the relationships among 35 orthologs and to calculate the ancestral sequences of these orthologs. By aligning sequences from the 35 orthologs and their ancestors and categorizing amino acid sites by degree of conservation, we used comparative evolutionary methods to determine potential functionally important amino acid sites in Cx26 and to identify missense changes that are likely to affect function. We identified six conserved regions in Cx26, five of which are located in the Connexin_CCC, and another is in the connexin super family domain. Finally, we identified 51 missense changes that are likely to disrupt function, and the probability of these changes occurring at hydrophilic amino acid residues was twice that of occurring at hydrophobic residues in the trans-membrane regions of Cx26. Our findings, which were obtained by combining comparative evolutionary methods to predict Cx26 mutant function, are consistent with the pathogenic characteristics of Cx26 mutants. This study provides a new pathway for studying the role of aberrant Cx26 in hereditary hearing loss.

Migration and differentiation of mouse embryonic stem cells transplanted into mature cochlea of rats with aminoglycoside-induced hearing loss.

CONCLUSION: Mouse embryonic stem cells (ESCs) transplanted into the scala tympani are able to migrate in the cochlea of rats deafened with aminoglycoside and partly restore the structure of sensory epithelia of the inner ear. OBJECTIVES: To explore the migration and differentiation of enhanced green fluorescence protein (EGFP)-expressing ESCs by transplanting them into the scala tympani of rats with amikacin sulfate-induced hearing loss. METHODS: Adult Sprague-Dawley (SD) rats were deafened with amikacin sulfate. Mouse ESCs expressing EGFP (EGFP-ESCs) were transplanted into the scala tympani. The migration and differentiation were observed at different time points. RESULTS: EGFP-ESCs transplanted into normal cochlea did not migrate, but those in the amikacin-damaged cochlea could survive and migrate into the scala media and the vestibular cisterna. For the first time, we observed that the EGFP-ESCs migrated into the scala media, took the place of the organ of Corti, and formed a structure just like the cochlear tunnel. Some grafted stem cells even expressed myosin VIIa, the molecular marker of hair cells. Some nerve fibers reached to the bottom of the hair cell-like cells. The ESCs migrated into the vestibule and restored the sensory epithelia of the ampullary crest. The number of the transplanted ESCs reduced over the 6 week period of the study.

[Comparative analysis of conservation and regulatory network on core transcription factors in mouse inner ear development].

During vertebrate inner ear development, several core genes, such as Six1, Six4, Pax2, Pax8, Foxi1, Dlx5, Gbx2, Irx2/3, and Msx1, are crucial to the regulation of the otic placode induction. In order to get the gene regulatory network during inner ear development, bioinformatics methods were adopted to analyze conservation and regulation of the core transcription factors in mice. Pax2, Pax8, Foxi1, and Dlx5 remained to be the main regulators during inner ear development, which was consistent with the gene regulatory network from literature. Six1 was regulated by many transcription factors, and Gbx2, Irx2/3, and Msx1 played important roles in the regulatory network. The differences in the constructed regulatory network were reasonably analyzed. It was predicted that Msxl regulated the expression of Six1 and Gbx2. In addition, several transcription factors, such as Sox5, Lhx2, Rax, Otx1, Otx2, Pitxl, Pitx2, Nkx2-5, Irx4, Irx6, Dlx2, Hmx1/2/3, Pou4f3, Pax4 and Tlx2, were found to be involved in the regulatory network. Our results provide an improved understanding of the regulatory mechanism during inner ear development.

Effects of hypoxia-inducible factor 1α on bone conduction impairment in otitis media with effusion.

CONCLUSION: Elevated levels of hypoxia-inducible factor 1α (HIF-1α) in middle ear effusion may play an important role in the pathogenesis of bone conduction impairment associated with otitis media with effusion (OME). The mechanism may be related to the up-regulation of nitric oxide (NO) expression. OBJECTIVES: This study was undertaken to investigate the role of HIF-1α in the pathogenesis of sensorineural hearing loss associated with OME. METHODS: One hundred and eight OME patients were divided into two groups: OME without bone conduction impairment (group 1) and OME with bone conduction impairment (group 2). The levels of HIF-1α, NO, and quinolinic acid (QUIN) in the middle ear effusion and serum of these patients were investigated. The relationship between these factors and the bone conduction threshold (BCT) differences were analyzed. RESULTS: The levels of HIF-1α and NO concentrations in the middle ear effusion were found to be significantly higher in group 2 than in group 1 (both p < 0.05). The OME patients' BCT differences at 4000 Hz were correlated with the levels of HIF-1α and the NO concentrations in the middle ear effusion. Furthermore, the HIF-1α levels were correlated with the levels of NO but not with the levels of QUIN in the effusion.

Single nucleotide polymorphisms and haplotypes analysis of DFNB1 locus in Chinese sporadic hearing impairment population.

BACKGROUND: The DFNB1 locus, which contains the gap junction beta-2 (GJB2) and gap junction beta-6 (GJB6) genes, plays a key role in the nonsyndromic and sporadic hearing impairment. Mutations of DFNB1 result in autosomal recessive nonsyndromic hearing impairment (ARNSHI). Previous researches have identified mutations in GJB2 and GJB6, but single nucleotide polymorphisms (SNPs) of DFNB1 locus have not been studied. So we chose five SNPs to evaluate whether there is difference between deafness people and normal-hearing people in Han Chinese. METHODS: Five SNPs in the DFNB1 region were examined using a case-control association study between cases with sporadic hearing impairment and controls with normal hearing. The HWEsoft and SHEsis softwares were used to analyze the results. RESULTS: Single-locus association analysis showed a positive association for three SNPs: rs9315400, rs2274084 and 235delC. When we compared the distributions of the haplotypes, we also found significant differences between cases and controls in the haplotype combination of rs2274084 and rs2274083 (chi(2) = 12.978, df = 3, global P = 0.004719). CONCLUSIONS: The haplotypes composed of rs2274084 and rs2274083 suggested that C-C may be a risk haplotype for the sporadic hearing impairment while T-T may be protective against hearing impairment. From that point of view, we can conclude that the SNPs of DFNB1 locus also plays an important role in sporadic hearing impairment cases.

[Epidemiologic study on hearing impairment and ear diseases in old people].

OBJECTIVE: To investigate the prevalence of hearing impairment and ear diseases in old people and provide scientific data for drawing up the prevention and treatment strategies. METHODS: Using the probability proportion to size (PPS) method, 1261 people over 60 years were investigated in 40 clusters in Jiangsu Province with the WHO protocol. RESULTS: The prevalence of hearing impairment was 58.1% (the standardized rate: 59.5% in the whole country, 60.9% in Jiangsu province). Degrees of hearing impairment were mild (33.1%), moderate (17.8%), severe (5.9%) and profound (1.3%). The prevalence of hearing disability was 25.0% (the standardized rate: 26.6% in the whole country, 28.1% in Jiangsu province). There were significant difference of the prevalence between male and female, as well as urban and rural, and different ages. The prevalence of the ear diseases was auricle malformation (0.2%), wax (1.7%), otitis externa (0.1%), fungi (0.5%), serous otitis media (1.2%), chronic suppurative otitis media (1.6%), dry perforation of tympanic membrance (2.3%). The causes of hearing impairment were ear diseases (2.9%), non-infectious condition (92.6%), genetic condition (0.3%) and undetermined causes (4.2%). Of which, 31.1% of persons needed hearing aids while 2.3% of persons needed medicine treatment, but 0.9% of persons needed non-urgent surgery and 1.0% of persons needed other treatment. CONCLUSIONS: The prevalence of hearing impairment and disability in the old rised obviously than the last investigation in 1987. It was a heavy burden for social development in China. The government and the whole society should take more concern about the problem. The scientific strategies of prevention and treatment were urgently needed and implemented.

[Mitochondrial 12S rRNA gene A827G in two pedigrees with nonsyndromic deafness].

OBJECTIVE: To investigate the relationship of associating mitochondrial DNA 12S rRNA gene mutations with non-syndromic and aminoglycoside-induced hearing loss happening to Chinese families. METHODS: The diagnosis was validated by hearing tests. Blood samples were collected from 20 family members (13 subjects from pedigree A and 7 from pedigree B) and 32 sporadic deafness cases. DNA was extracted from the leukocytes in blood samples. The gene fragments of mitochondrial DNA 12S rRNA, tRNA(Ser(UCN)) and GJB(2) were amplified by polymerase chain reaction (PCR). PCR products were analyzed by sequencing. RESULTS: The target gene fragments of all individuals were successfully amplified by PCR. The mitochondrial DNA 12S rRNA 827 A to G transition was detected from all maternal members including 12 patients with hearing loss, which was the homoplasmic mutation. Non-maternal members in two pedigrees did not carry this mutation. However, the tRNA(Ser(UCN)) A7445G, 12SrRNA A1555G and GJB2 gene mutations were not found from both the family members of two pedigrees and sporadic patients. One sporadic individual (1/32) who was diagnosed as aminoglycoside-induced hearing impairment carried A827G mutation too. CONCLUSION: It is confirmed that the mitochondrial DNA 12S rRNA gene is a hot spot for mutations associated with non-syndromic inherited hearing loss. The 12S rRNA nt827 A to G mutation may play a pivotal role in the pathogenesis of hearing impairment in two Chinese pedigrees.

[Sequence analysis of the connexin 26 genes from a deafness family with A1555G mutation in Huaiyin].

OBJECTIVE: To ascertain whether connexin 26 (Cx26) gene was a nuclear modifier gene in an extensive family with matrilineal nonsyndromic deafness associated with A1555G mutation in Huaiyin, China. METHODS: Following PCR-restriction fragment length polymorphism (PCR-RFLP) with ApaI restriction enzyme, Cx26 genes from 26 cases, with A1555G mitochondrial mutations in this family, and 62 controls (including 2 patrilineal relatives, 10 spouse controls and 50 unrelated controls), were sequenced. RESULTS: Compared with the reference sequence of Cx26 gene, totally four kinds of nucleotide changes,79G -->A, 109G-->A, 341G-->A and 235delC, were detected in a heterozygous form. However, the former three were previously reported polymorphisms, and only the 235delC was a previously described recessive mutation associated with most autosomal nonsyndromic sensorineural hearing loss in Japan and China. Further study showed that the heterozygous 235delC mutation existed in both one individual with mild hearing loss and two individuals with normal hearing. Clinical characterization showed that 235delC mutation did not seem to modify the deafness phenotype due to the A1555G mutation. Moreover, this 235delC mutation was deduced to derive from a married-in control. Finally, there were no co-segregation between the phenotypes of hearing loss and the genotypes for Cx26 genes based on the four kinds of nucleotide changes. CONCLUSIONS: The heterozygous 235delC mutation of the Cx26 gene may not modulate the severity of hearing loss associated with A1555G mutation and Cx26 gene is unlikely to be a modifier gene for hearing loss due to A1555G mitochondrial mutation in this Chinese family.

[Clinical study of acute low-tone sensorineural hearing loss].

OBJECTIVE: To explore the etiology, clinical aspects, diagnosis and therapeutic strategies of acute low-tone sensorineural hearing loss (ALHL). METHODS: Thirty patients (31 ears) with ALHL were selected for this study. Detailed history collection, otological examination and systematic audiological evaluations were conducted. The hearing tests included pure tone audiometry, acoustic immittance, auditory brainstem response (ABR) and otoacoustic emissions (OAE). All cases received therapeutic trial of corticosteroid for 15 days with 6 to 14 months' following-up. RESULTS: ALHL mainly affected young people. Low-tone tinnitus, a sensation of ear fullness and hearing impairment were the frequent complains. Otological examinations showed normal results. Mild to moderate sensorineural hearing loss at low frequencies and type "A" tympanograms were found in all patients. Acoustic stapedial reflexes were elicited in 26 of 31 affected ears, and 14 of them had positive results on the Metz test. ABR responses were normal in all 20 tested ears. In 14 out of 20 ears, TEOAEs were absent and DPOAE grams at low frequencies (0.5, 0.75 kHz) were abnormal on the first visit. After steroid therapy, 24 ears demonstrated complete recovery, but 4 ears showed partial recovery and 3 ears unchanged. The total improvement rate was 90.3%. CONCLUSIONS: ALHL patients are clinically characterized by low-tone tinnitus, aural fullness and hearing loss, which mainly involved unilateral ear. Audiological findings indicate a cochlear impairment, which only invades low frequency region. The basic pathological feature may be endolymphatic hydrops involves immune response. Conflicting data exist on whether ALHL is an independent disorder or a subtype of Meniere's disease. Ideal therapeutic strategy has not been established by now and corticosteroid is probably an effective agent.

[Nonsyndromic inherited hearing impairment caused by mtDNA double mutations of A1555G and 961 insC].

OBJECTIVE: To investigate the genotypes of mitochondrial DNA mutations of a large nonsyndromic inherited hearing impairment pedigree. METHODS: The diagnosis was validated by hearing test. Blood samples from the branch pedigree (33 members) and 6 sporadic patients were obtained. DNA was extracted from the leukocytes. The mitochondrial DNA target fragments were amplified by polymerase chain reaction(PCR). The 1555G, 3243G and 7445G mutations were detected by BsmA I, Apa I and Xba I restriction endonuclease digestion respectively. Some PCR products were analyzed by sequencing. RESULTS: Restriction endonuclease digestion identified that 17 patients from the pedigree carried 1555G mutation. All pedigree members, including patients and sporadic patients, did not have 3243G and 7445G mutation. In 6 patients of the pedigree DNA sequence analysis revealed double mutations, an A>G transition at position 1555 and a C insertion at position 961, whereas the unaffected relatives of the pedigree and sporadic patients did not have such mutations. None of them carried 3243G and 7445G mutation. CONCLUSION: Double mutations of A1555G and 961 insC in mitochondrial DNA 12S rRNA gene region may play a pivotal role in the pathogenesis of hearing loss in the large nonsyndromic inherited hearing impairment pedigree.

[Transmaxillary approach for micro resection of clivus tumors, clinical analysis of 16 cases].

OBJECTIVE: To investigate the indications, key point, advantages, and disadvantages of transmaxillary approach for microsurgical removal of clivus tumors. METHODS: The clinical data of 16 consecutive patients with clivus tumors operated upon through transmaxillary approach, based on Le Fort I ostectomy, July 1999 to May 2002 were retrospectively reviewed. RESULTS: Of the 16 patients, 8 patients suffered from chordoma, 2 from angiofibroma, 1 from pituitary adenoma, 1 from chondroma, 1 from adenocarcinoma of grade II, 1 from mucoid cyst, 1 from myeloma, and 1 from fibrous dysplasia of bone. Four out of the 16 cases were with recurrent tumors after operation performed in other hospitals. The operation field of all 16 patients was satisfactorily exposed. The tumors of 10 cases were totally removed under microscope, and 6 tumors were subtotally removed. The complications included rhinorrhea in 1 case and malocclusion in 3 cases. There was no operative mortality. All patients were followed up for 6 approximately 40 months (ion average 20 months) with MRI. Four of them had local recurrence within 1 year, 1.5 years, 2 years, and 9 months respectively after operational and have lived with tumors till now. The remainders had resumed their normal life. CONCLUSION: An ideal approach, transmaxillary approach facilitates the resection of clivus tumors, with satisfying exposure and fewer complications.

[Neurophysiological characteristics of infants and young children with auditory neuropathy].

OBJECTIVE: To analyze the neurophysiological characteristics of infants and young children with auditory neuropathy (AN) and explore their clinical significance. METHODS: Audiological measurements (acoustic immittance, EOAEs, ABR, CM, MLR and ERP) and peripheral neurological tests were conducted and evaluated in 13 infants and young children with AN. 6 AN patients received CT scan and/or MRI examination. RESULTS: All patients had type "A" tympanogram and normal CM. Normal EOAEs were elicited in 12 patients. 8 cases had normal MLR recording and 6 cases had normal ERP (P(300) and MMN). Peripheral neurological tests and CT and/or MRI showed normal results. CONCLUSION: The diagnosis of AN in infants and young children should focus on analyzing their neurophysiological characteristics. Combined use of EOAEs, ABR and CM was recommended for hearing screening on newborns with high risk factors.