[Late-onset hereditary hearing loss caused by TMPRSS3 compound heterozygous mutations].

Objective:This study aims to identify the genetic etiology underlying late-onset hearing loss in two unrelated Chinese families. Methods:Detailed clinical data of recruited participants of two families were collected and analyzed using next-generation sequencing, combined with Sanger sequencing and bioinformatics tools. Results:Patients in both families manifested as down-sloping audiograms, mainly with severe mid-to-high frequency hearing loss as well as decreased speech recognition rate, both of which occurred during the second decade. Next-generation sequencing panels succeeded in identifying mutations in gene TMPRSS3, and three heterozygous mutations were screened out, among which c. 383T>C was the first reported mutation. In silico functional analysis and molecular modeling defined the five mutations as "pathogenic" or "likely pathogenic" according to official guideline. Conclusion:The novel mutation combinations in TMPRSS3 gene segregated with an exclusive auditory phenotype in the two pedigrees. Our results provided new data regarding the characteristic deafness caused by TMPRSS3 mutations during adolescent period when hearing should be closely monitored.

Characterization of the components in plasma EVs unveiling the link between EVs-derived complement C3 with the severity and initial treatment response of profound sudden sensorineural hearing loss.

BACKGROUND: Sudden sensorineural hearing loss (SSNHL) is characterized by rapid, unexplained loss of hearing within a 72-hour period and exhibits a high incidence globally. Despite this, the outcomes of therapeutic interventions remain largely unpredictable, especially for those with profound hearing loss. Extracellular vesicles (EVs), nano-sized entities containing biological materials, are implicated in the development of numerous diseases. The specific relationship between EVs and both the severity and treatment effectiveness of SSNHL, however, is not well understood. METHODS: This study involved the analysis of medical records from the Department of Otolaryngology (September 1, 2020 - December 31, 2022) of patients diagnosed with SSNHL according to the 2015 Guidelines for Diagnosis and Treatment of Sudden Deafness in China. Peripheral blood samples from patients with various types of SSNHL before and after treatment were collected, alongside samples from healthy volunteers serving as controls. Plasma EVs were isolated using gel rejection chromatography and analyzed for concentration, marker presence, and morphology using Nanosight, Western blot, and transmission electron microscopy (TEM), respectively. Proteomics and miRNA assessments were conducted to identify differentially expressed proteins and miRNAs in the plasma EVs of SSNHL patients and healthy volunteers. Key proteins were further validated through Western blot analysis. Enzyme-linked immunosorbent assay (ELISA) was utilized to determine the levels of complement C3 in plasma EVs, and correlation analyses were performed with audiological data pre- and post-treatment. RESULTS: Plasma from SSNHL patients of varying types was collected and their EVs were successfully isolated and characterized. Proteomic analysis revealed that complement C3 levels in the plasma EVs of patients with profound SSNHL were significantly higher compared to healthy controls. Differential expression of miRNAs in plasma EVs and their related functions were also identified. The study found that the level of complement C3 in plasma EVs, but not the total plasma complement C3, positively correlated with the severity of SSNHL in patients exhibiting positive therapeutic responses, particularly in those with initially lower levels of EV-associated complement C3. After treatment, complement C3 level was decreased in patients with initially higher levels of EV-associated complement C3. No significant correlation was observed between changes in plasma EV-derived complement C3 levels and the degree of hearing loss in either responders or non-responders among patients with profound SSNHL. CONCLUSION: Differential profiles of proteins and miRNAs were identified in patients with profound SSNHL. Notably, plasma EV-derived complement C3 was linked to both the severity and early treatment effectiveness of patients with profound SSNHL.

Deficient gap junction coupling of two common hearing loss-related variants in GJB2.

Objectives: To explore the functional consequences of two common variants, p.V37I and c.299-300delAT in hearing loss associated gene GJB2. Methods: Connexin 26 expression and gap junctional permeability were studied in HEK 293T cells transfected with plasmids expressing GJB2 wild-type, p.V37I, or c.299-300delAT CX26 proteins with fluorescent tags. Functional analyses of different GJB2 haplotypes were performed to fully assess the alteration of ionic and small-molecule coupling. Results: The p.V37I protein was localized at the plasma membrane, but failed to effectively transport intercellular propidium iodide or Ca2+ efficiently, indicating impairment of both biochemical and ionic coupling. The presence of GJB2 p.V37I appeared to increase the sensitivity of cells to H2O2 treatment. In contrast, the known variant c.299-300delAT protein was not transported to the cell membrane and could not form gap junctions, instead being confined to the cytoplasm. Ionic and biochemical coupling was defective in c.299-300delAT-transfected cells. Conclusion: The p.V37I and c.299-300delAT GJB2 mutations resulted in deficient gap junction-mediated coupling. Environmental factors may impact the functional consequences of GJB2 p.V37I. These results may inspire the development of molecular therapies targeting GJB2 mutations for hearing loss.

A dominant variant in apoptosis-related gene XKR8 is relevant to hereditary auditory neuropathy.

BACKGROUND: Auditory neuropathy is an unusual type of hearing loss. At least 40% of patients with this disease have underlying genetic causes. However, in many hereditary auditory neuropathy cases, etiology remains undetermined. METHODS: We collected data and blood samples from a four-generation Chinese family. After excluding relevant variants in known deafness-related genes, exome sequencing was conducted. Candidate genes were verified by pedigree segregation, transcript/protein expression in the mouse cochlea, and plasmid expression studies in HEK 293T cells. Moreover, a mutant mouse model was generated and underwent hearing evaluations; protein localization in the inner ear was also assessed. RESULTS: The clinical features of the family were diagnosed as auditory neuropathy. A novel variant c.710G > A (p.W237X) in apoptosis-related gene XKR8 was identified. Genotyping of 16 family members confirmed the segregation of this variant with the deafness phenotype. Both XKR8 mRNA and XKR8 protein were expressed in the mouse inner ear, predominantly in regions of spiral ganglion neurons; Moreover, this nonsense variant impaired the surface localization of XKR8 in cells. Transgenic mutant mice exhibited late-onset auditory neuropathy, and their altered XKR8 protein localization in the inner ear confirmed the damaging effects of this variant. CONCLUSIONS: We identified a variant in the XKR8 gene that is relevant to auditory neuropathy. The essential role of XKR8 in inner ear development and neural homeostasis should be explored.

Report of rare and novel mutations in candidate genes in a cohort of hearing-impaired patients.

BACKGROUND: Many hearing-impaired patients carry mutations in rare or novel genes undetected in regular genetic hot regions/genes screening. METHODS: We collected clinical and genetic data from subjects with hearing loss who visited our department for genetic counseling. Next-generation sequencing was conducted after 154 deafness-related genes were captured using a designed genes panels in 14 unrelated families (37 participants). The results were filtered and assessed with in silico tools, in combination with pedigree mapping. RESULTS: Ten mutations in regular deafness genes (GJB2, SLC26A4) and uncommon genes (OTOF, MYO7A, MYO15A, and KARS) were detected, which constituted 57.2% of yielded rate. In particular, two patients with nonsyndromic deafness carried biallelic KARS mutations. In addition, we identified an unreported digenic mutational inheritance in GRP98/USH2A genes in a proband with isolated hearing loss. Functional analyses and molecular modeling suggested the damaging consequence of these variants on encoded proteins. According to the variant pathogenicity guidelines, the 17 identified variants in total were classified as "pathogenic" or "likely pathogenic." CONCLUSION: The candidate mutations in deafness genes were suggested to be co-segregated in at least 57.2% of the studied pedigrees. This is the new report of rare/novel mutations causing inherited hearing loss in Chinese.

Labyrinthine lesions in presumed inner ear hemorrhage-related sudden deafness.

PURPOSE: Inner ear hemorrhage (IEH) is a rare cause of sudden sensorineural hearing loss (SSNHL). This study aimed to evaluate the lesional patterns in patients with presumed IEH from morphological and functional aspects. METHODS: Seventeen patients with SSNHL and presumed IEH who completed audio-vestibular tests were included. The main outcome measures included clinical characteristics, radiology, and functional test results. RESULTS: The morphological findings and functional tests revealed differences in locations and lesional spectrums. The magnetic resonance imaging (MRI) hyperintensity was likely to involve the vestibule (88.2%), the cochlea (76.5%), and the posterior and lateral semicircular canals (76.5% and 70.6%, respectively). Furthermore, 70.6% of cases showed abnormality in the entire labyrinth, and abnormalities in the vestibule/semicircular canals were observed in 17.6% of cases. Meanwhile, dysfunction was sequentially detected in the cochlea (100%), semicircular canals (94.1%), and vestibule (70.6%); 64.7% of cases showed combined deficit in the entire labyrinth, and 29.4% of cases showed combined deficit in the cochlea/semicircular canals. Although lesions in the labyrinth were frequently detected, the results of the radiological and functional tests did not always match and significantly differed in either cochlear or superior semicircular canal damage detection (p < 0.05 each). CONCLUSIONS: In this cohort, IEH preferentially caused sudden audio-vestibular impairment, which was well demonstrated by a combination of MRI and functional tests. The specific lesional configurations revealed in this study may suggest a possible pathomechanism that could be further explored as a therapeutic target.

Cochlear Implantation Outcomes in Children With CDH23 Mutations-Associated Hearing Loss.

OBJECTIVE: Mutations in the cadherin 23 gene (CDH23) have been reported to cause cochlear damage, but few studies have investigated the auditory and speech outcome of patients after cochlear implantation. Here, we describe the genetic, auditory, and postoperative outcomes of patients with CDH23 mutations who received cochlear implants. STUDY DESIGN: Retrospective case review. SETTING: Tertiary referral center. METHODS: Targeted deafness-related gene panels were sequenced in Chinese families with profound sensorineural hearing loss. The clinical features of subjects carrying potentially pathogenic CDH23 mutations were analyzed. RESULTS: Between 2017 and 2019, we identified 5 children with prelinguistically profound hearing loss at our center who harbored 6 variants of CDH23 that segregated with the disease. Of these, 4 variants were novel (c.2591G>T, c.4785G>C, c.5765A>G, and c.9280_9281insTT). All affected individuals had a loss of outer hair cell function, with an average residual hearing level of 3 to 10 dB SPL. Cochlear implantations were arranged for the patients at 11 to 36 months of age. All children made gains in their hearing, language, and speech performances 14 to 120 months after surgery. Their auditory outcomes improved during follow-up intervals. CONCLUSION: This study revealed that children with congenital cochlear defects caused by CDH23 variants can acquire an acceptable auditory and speech outcome after cochlear implantation. Early genetic detection and prenatal counseling for rare deafness genes such as CDH23 remain a priority for the future.

Early Functional and Cognitive Declines Measured by Auditory-Evoked Cortical Potentials in Mice With Alzheimer's Disease.

Alzheimer's disease (AD) is characterized by a progressive loss of memory and cognitive decline. However, the assessment of AD-associated functional and cognitive changes is still a big challenge. Auditory-evoked cortical potential (AECP) is an event-related potential reflecting not only neural activation in the auditory cortex (AC) but also cognitive activity in the brain. In this study, we used the subdermal needle electrodes with the same electrode setting as the auditory brainstem response (ABR) recording and recorded AECP in normal aging CBA/CaJ mice and APP/PS1 AD mice. AECP in mice usually appeared as three positive peaks, i.e., P1, P2, and P3, and three corresponding negative peaks, i.e., N1, N2, and N3. In normal aging CBA mice, the early sensory peaks P1, N1, and P2 were reduced as age increased, whereas the later cognitive peaks N2, P3, and N3 were increased or had no changes with aging. Moreover, the latency of the P1 peak was increased as age increased, although the latencies of later peaks had a significant reduction with aging. In AD mice, peak P1 was significantly reduced in comparison with wild-type (WT) littermates at young ages, proceeding AD phenotype presentation. In particular, the later cognitive peak P3 was diminished after 3 months old, different from the normal aging effect. However, the latencies of AECP peaks in AD mice generally had no significant delay or changes with aging. Finally, consistent with AECP changes, the accumulation of amyloid precursor protein (APP) at the AC was visible in AD mice as early as 2 months old. These data suggest that AECP could serve as an early, non-invasive, and objective biomarker for detecting AD and AD-related dementia (ADRD).

MiR-146a Promotes Tolerogenic Properties of Dendritic Cells and through Targeting Notch1 Signaling.

BACKGROUND: MiR-146a has been shown to negatively regulate innate immune, inflammatory response and antiviral pathway, however, its role in the tolerogenic responses remains largely unknown. This study aimed to investigate the role of miR-146a in the OVA-induced allergic inflammation of dendritic cells (DCs). METHODS: Bone marrow-derived DCs (BMDCs) were treated with OVA (100 µg/ml) for 24 h. MiR-146a expressions were assessed by quantitative RT-PCR. BMDCs were transfected with miR-146a mimics or inhibitor. Cell surface markers were analyzed by flow cytometry. Cytokine levels were determined by ELISA assay. Mixed lymphocyte culture assay was adopted to assess CD4 + T-cell differentiation. The 3' UTR luciferase reporter assay was utilized to determine the miRNA target sequence. RESULTS: OVA treatment significantly up-regulated miR-146a in BMDCs in a dose- and time-dependent manner. In the OVA-treated DCs, overexpression of miR-146a (mimics transfection) down-regulated the surface markers (CD80, CD86) and increased production of anti-inflammatory cytokines TGF-ß1 and IL-10 but decreased pro-inflammatory cytokine IL-12. MiR-146a overexpression promoted immature DC to induce regulatory T cells (Treg) differentiation. By contrast, transfection of miR-146a inhibitor into DC exhibited the opposite trends. Notch1 was a direct target of miR-146a, and Notch1 knock-down induced similar effects as miR-146a mimics transfection in BMDCs. Moreover, the effect of miR-146a inhibitor on OVA-induced DC was attenuated by Notch1 knock-down. CONCLUSION: miRNA-146a promoted tolerogenic properties of DCs, at least partially, through targeting Notch1 signaling.

Hearing loss is an early biomarker in APP/PS1 Alzheimer's disease mice.

Alzheimer's disease (AD) is a neurodegenerative disease characterized by a progressive loss of memory and cognitive decline. Over the last decade, it has been found that defects in sensory systems could be highly associated with AD. Hearing is an important neural sense. However, little is known about hearing functional changes in AD. In this study, APP/PS1 AD mice (Jackson Lab: Stack No. 004462) were used. Hearing function was assessed by auditory brainstem response (ABR), distortion product otoacoustic emission (DPOAE), and cochlear microphonics (CM) recordings. Wild-type (WT) littermates served as control. We found that APP/PS1 AD mice measured as ABR threshold had hearing loss. The hearing loss appeared at high frequency as early as 2 months old, prior to the reported occurrence of spatial learning deficit at 6-7 months of age in this AD mouse model. The hearing loss was progressive and extended from high frequency to low frequency. At 3-4 months old, the hearing loss appeared in the whole-frequency range. Moreover, the wave IV and V in the super-threshold ABR were eliminated, indicating substantial impairment in inferior colliculus, nuclei of lateral lemniscus, and medial geniculate body in the upper brainstem. DPOAE in APP/PS1 AD mice was also reduced. However, there was no reduction in CM in APP/PS1 mice. These data demonstrate that unlike age-related hearing loss APP/PS1 AD mice have early onset of hearing loss. These data also suggest that hearing function testing could provide a simple, sensitive, non-invasive screen-tool for early detecting AD and localizing lesion.

Different prognoses in patients with profound sudden sensorineural hearing loss.

Background: Inner ear hemorrhage is increasingly recognized as a cochlear lesion that can cause profound sudden sensorineural hearing loss (SSNHL). Objectives: To investigate changes of cochlear and vestibular function and to compare therapeutic recovery from profound SSNHL induced by different etiologies. Material and methods: Eighty patients with profound SSNHL (≥90 dB) were divided into an inner ear hemorrhage group and a non-inner ear hemorrhage group by MRI. Statistical analysis was performed to compare the therapeutic effects from vertigo and hearing loss and the outcomes of follow-up in the two groups. Results: There were significant differences between the two groups in terms of the overall 14-day therapeutic response rate (20 vs. 48%), the incidence of imbalance (26.7 vs. 6%), the incidence of semicircular canal dysfunction on the affected side (60 vs. 20%), the incidence of abnormal C-VEMP and O-VEMP on the affected side (63.3 vs. 38%; and 60 vs. 30%, respectively), the average hearing threshold (74.2 ± 10.7 vs. 53.6 ± 11.4 dB), and the word recognition score (65.5 ± 21.7 vs. 83.5 ± 24.5%) at a 12-month follow-up. Conclusions and significance: A higher percentage of patients with profound SSNHL induced by inner ear hemorrhage were associated with vertigo and had a poor prognosis.

Audiological outcomes in sudden sensorineural hearing loss with presumed inner ear hemorrhage.

OBJECTIVE: To explore the hearing outcomes and prognostic factors in patients with sudden sensorineural hearing loss resulting from inner ear hemorrhage. METHODS: 42 patients (22 male and 20 female) were recruited from January 2016 to December 2017. Intravenous methylprednisolone and/or intratympanic corticosteroid were used as salvage therapy. The main measures included systemic risk factors and audiometric outcomes as proposed by American Academy of Otolaryngology-Head and Neck Surgery Hearing Loss Scale. All individuals were assessed at baseline, discharge (2 weeks post-treatment) and at 1, 3 and 6 months. RESULTS: The mean ages of patients were 39.3 ±â€¯14.8 yrs. Cardiovascular disorders were seen in 19.0-33.3% of cases. Restoration of hearing and speech discrimination abilities were assessed at the first month post-treatment versus initial levels (95.5 ±â€¯15.5 vs. 109.2 ±â€¯9.6 dB, p = 0.000; and 17.6 ±â€¯24.4 vs. 1.3 ±â€¯4.0%, p = 0.003, respectively). Word recognition scores continued to recover at month 6 (38.7 ±â€¯35.4%, p = 0.000), whereas puretone ceased to change (90.8 ±â€¯16.2 dB, p = 0.139). The final percentages of complete, partial and no recovery were 0%, 57.1% and 42.9% respectively. The prognosis was independent of accompanying systemic risk factors as analyzed in this study. Intratympanic intervention was associated with improved word recognition scores, although intravenous corticosteroid was not. CONCLUSIONS: Profound sudden sensorineural hearing loss caused by inner ear hemorrhage often has an unsatisfactory prognosis. However, this cohort did experience partial audiological recovery with delayed onset. Immediate and effective intratympanic corticosteroid may have therapeutic potential for this intractable disease.

Targeted next generation sequencing reveals OTOF mutations in auditory neuropathy spectrum disorder.

OBJECTIVE: To study the genetic etiology of auditory neuropathy spectrum disorder (ANSD) in a Chinese family and perform a literature review of OTOF mutations and cochlear implantation (CI). METHODS: Sequential targeted next generation sequencing (NGS) and CI was performed for the proband. Further, 50 DNA samples from unrelated families with nonsyndromic deafness were examined for frequency determination. The impact of OTOF mutations on hearing recovery after CI was assessed through the literature survey. RESULTS: In the proband, the targeted NGS panel revealed five suspected variants in four genes (OTOF, EYA4, PCDH15, and GIPC3), of which two mutations-c.5098G > C (p.Glu1700Gln) and c.1702C > T (p.Arg568Trp)-in the OTOF gene were found to be correlated with ANSD. The c.5098G > C allele was identified in only one child from the 50 unrelated participants. The proband's hearing and speech abilities were restored 2 years after the surgery. Most ANSD patients (90.9%; 30/33) with OTOF mutations have acceptable surgical outcomes, as indicated by existing reports. CONCLUSIONS: Our results support the feasibility of CI for patients with ANSD and OTOF mutations, and this hypothesis was supported by the review of existing data. A larger number of cases studies is required to determine possible modifies on the prognosis of surgery.

Side-related differences in sudden sensorineural hearing loss in children.

OBJECTIVE: Most studies on sudden sensorineural hearing loss (SSNHL) do not differentiate the outcomes within varied affected ears in children. The present study was designed to determine the clinical differences between unilateral and bilateral SSNHL in children. METHODS: The clinical data, from a total of 101 pediatric patients with SSNHL, was retrospectively analyzed from January 2003 to December 2016. The main outcome measures included basic characteristics, etiology, clinical symptoms and treatment courses. RESULTS: When the bilateral group (n = 28) was compared to the unilateral group (n = 73), neither gender nor onset of SSNHL was significantly different (p > 0.05 each); However, bilateral SSNHL tended to occur in younger ages (8.1 ±â€¯4.0 yrs), with higher percentages of suspected etiologies (50%) and proportion of profound deafness (55.4%, p < 0.05 each). The short-term recovery rate was superior in the unilateral cases over the bilateral cases (37.0% vs. 12.5%, p < 0.05). Milder initial hearing threshold, early onset of treatment (5.6 ±â€¯4.8 days) with unilateral involvement and an older age (11.3 ±â€¯3.0 yrs) in bilaterally affected cases were associated with a better prognosis in this cohort. In addition, the unilateral group showed comparable outcomes, when sub-analyzed by comparison to that in either left- (n = 42) or right-sided (n = 31) SSNHL. CONCLUSION: Although bilateral and unilateral pediatric SSNHL could cause partial to complete cochlear lesion, they may be relevant to distinct backgrounds. Our data also provides valuable information about demographics and outcomes of SSNHL in children.

GJB3/GJB6 screening in GJB2 carriers with idiopathic hearing loss: Is it necessary?

BACKGROUND: Genetic analysis detected excessive mono-allelic recessive GJB2 mutations in individuals with idiopathic deafness; the remaining alleles in trans/cis are underdetermined. The aim of this study was to assess the contributions of variants in GJB3 or GJB6 to non-syndromic sensorineural hearing impairment (NSHI) in Chinese patients with mono-allelic GJB2 mutations. METHODS: The entire coding sequences of GJB3/GJB6, as well as deletions in GJB6, in a cohort of NSHI patients (n = 100) carrying likely pathogenic heterozygous GJB2 mutations, were tested. Targeted next generation sequencing was further performed in a multiplex family GDHY with moderate to profound NSHI. RESULTS: Putatively causative GJB3 variant underlied 1% (1/100) in this cohort. In family GDHY, we identified a rare GJB3 c.250G>A mutation, as double heterozygotes with GJB2 c.109G>A and/or a novel GJB2 mutation c.638T>C predicted to be damaging in a digenic inheritance after precluding other attributable mutations from 127 deafness genes. No GJB6 mutation was found. CONCLUSIONS: GJB3/GJB6 variants account for a low proportion in autosomal recessive GJB2 mutation carriers in our cohort. Environmental causes, or other NSHI relevant genes, revealed by targeted next generation sequencing or whole exome sequencing, may play major roles in triggering deafness in these patients.

microRNA­183 is involved in the differentiation and regeneration of Notch signaling­prohibited hair cells from mouse cochlea.

Auditory hair cell regeneration following injury is critical to hearing restoration. The Notch signaling pathway participates in the regulation of inner ear development and cell differentiation. Recent evidence suggests that microRNA (miR)­183 has a similar role in the inner ear. However, it is unclear how Notch signaling functions in hair cell regeneration in mammals and if there is cross­talk between Notch signaling and miR­183. The present study used a gentamicin­induced cochlear injury mouse model. Gentamicin­induced damage of the hair cells activated the Notch signaling pathway and downregulated miR­183 expression. Notch signaling inhibition by the γ­secretase inhibitor, 24­diamino­5­phenylthiazole (DAPT), attenuated gentamicin­induced hair cell loss and reversed the downregulation of miR­183 expression. Further investigation revealed that the novel hair cells produced, induced by DAPT, were derived from transdifferentiated supporting cells. Additionally, myosin VI­positive hair cell numbers were increased by Notch signaling inhibition in in vitro experiments with cultured neonatal mouse inner ear precursor cells. This effect was reversed by miR­183 inhibition. These findings indicate that the Notch signaling pathway served a repressing role during the regeneration of hair cells. Inhibiting this signal improved hair cell regeneration in the gentamicin­damaged cochlear model. miR­183 was demonstrated to be involved in hair cell differentiation and regeneration, and was required for the differentiation of the Notch­inhibited hair cells.

Delayed Recovery in Pediatric Sudden Sensorineural Hearing Loss Predicted via Magnetic Resonance Imaging.

OBJECTIVES: To evaluate the potential origins via magnetic resonance imaging and the relevant hearing recovery course of pediatric sudden sensorineural hearing loss. METHODS: We retrospectively analyzed data of 25 pediatric patients from our center with sudden sensorineural hearing loss from January 2011 to December 2016. All individuals were closely followed up at baseline and 1 and 6 months. RESULTS: Magnetic resonance imaging identified presumed causes in 9 cases, 5 of which showed intralabyrinthine hyperintensity, suggesting presumptive intralabyrinthine hemorrhage. The remaining 20 patients showed no hyperintensity. Restoration of hearing and speech discrimination abilities were noted in these 25 children at 6 months versus the initial levels (74.2 ± 22.6 vs 93.5 ± 20.5 dB, p = .000, and 45.8 ± 36.0 vs. 18.3 ± 22.1%, p = .004, respectively). The prognosis of the individuals with intralabyrinthine hemorrhage were superior in terms of frequency and hearing threshold at 6 months compared with that of the no-hemorrhage participants. Word recognition scores improved in either studied group. CONCLUSION: The potential recovery of hearing in children raises concerns about very early surgical intervention within the first 6 months. Rational imaging and sequential audiometric evaluation to monitor the progression of recovery may be beneficial.

MicroRNA-194 Regulates the Development and Differentiation of Sensory Patches and Statoacoustic Ganglion of Inner Ear by Fgf4.

BACKGROUND MicroRNA 194 is involved in the differentiation of various types of cells, such as adipose derived stem cells, human embryonic stem cells, and bone marrow mesenchymal stem cells. Previously, we found that miR-194 was highly expressed in the inner ear sensory patch and neurons in mice embryos. However, the role of miR-194 in the development of the inner ear and its underlying mechanism have not been elucidated yet. MATERIAL AND METHODS The expression level of miR-194 has been altered by using antisense morpholino oligonucleotides (MO) and synthesized miRNAs in zebrafish. RESULTS We found that miR-194 was vastly expressed in the inner ear and central nervous system (CNS) in zebrafish. Loss of function of miR-194 could strongly affected the development of zebrafish embryos, including delayed embryonic development, edema of the pericardium, small head, axial deviation, delayed development of inner ear, closer location of two otoliths, delayed fusion of the semicircular canals, and abnormal otolith number in some cases. In addition, the behavior of zebrafish was also adversely affected with impaired balance and biased swimming route. Misexpression of miR-194 could strongly affected the development and differentiation of spiral ganglion neuron (SGN) in inner ear through Fgf4 in vitro. Similar results have also been observed that the overexpression and knockdown of miR-194 strongly disturbed the development and differentiation of the sensory patches and Statoacoustic ganglion (SAG) through Fgf4 in zebrafish in vivo. Our results indicated that miR-194 may regulate the development and differentiation of sensory patches and SAG through Fgf4. CONCLUSIONS Our data revealed a vital role of miR-194 in regulating the development and differentiation of the inner ear.

Germinal mosaicism of PAX3 mutation caused Waardenburg syndrome type I.

OBJECTIVES: Waardenburg syndrome mutations are most often recurrent or de novo. The rate of familial recurrence is low and families with several affected children are extremely rare. In this study, we aimed to clarify the underlying hereditary cause of Waardenburg syndrome type I in two siblings in a Chinese family, with a mother affected by prelingual mild hearing loss and a father who was negative for clinical symptoms of Waardenburg syndrome and had a normal hearing threshold. METHODS: Complete characteristic features of the family members were recorded and genetic sequencing and parent-child relationship analyses were performed. RESULTS: The two probands were found to share double mutations in the PAX3/GJB2 genes that caused concurrent hearing loss in Waardenburg syndrome type I. Their mother carried the GJB2 c.109G > A homozygous mutation; however, neither the novel PAX3 c.592delG mutation, nor the Waardenburg syndrome phenotype, was observed in either parent. CONCLUSION: These previously unreported digenic mutations in PAX3/GJB2 resulted in deafness associated with Waardenburg syndrome type I in this family. To our knowledge, this is the first report describing germinal mosaicism in Waardenburg syndrome. This concept is important because it complicates genetic counseling of this family regarding the risk of recurrence of the mutations in subsequent pregnancies.

MiR-194 is involved in morphogenesis of spiral ganglion neurons in inner ear by rearranging actin cytoskeleton via targeting RhoB.

Many microRNAs participate in the development, differentiation and function preservation of the embryonic and adult inner ear, but many details still need to be elucidated regarding the numerous microRNAs in the inner ear. Based on previous investigations on the microRNA profile in the inner ear, we confirmed that several microRNAs are expressed in the inner ear, and we detected the spatial expression of these microRNAs in the neonatal mouse inner ear. Then we focused on miR-194 for its specific expression with a dynamic spatiotemporal pattern during inner ear development. Overexpression of miR-194 in cultured spiral ganglion cells significantly affected the dendrites of differentiated neurons, with more branching and obviously dispersed nerve fibres. Furthermore, the cytoskeleton of cultured cells was markedly affected, as disordered actin filaments resulting from miR-194 overexpression and enhanced filaments resulting from miR-194 knockdown were observed. Together with the bioinformatic methods, the RT-qPCR and western blot results showed that RhoB is a candidate target of miR-194 in the morphogenesis of spiral ganglion neurons. Additionally, the double luciferase reporter system was used to identify RhoB as a novel target of miR-194. Finally, the inhibition of RhoB activation by Clostridium difficile toxin B disturbed the organization of the actin filament, similar to the effects of miR-194 overexpression. In summary, we investigated microRNA expression in the mouse inner ear, and demonstrated that miR-194 is dynamically expressed during inner ear development; importantly, we found that miR-194 affects neuron morphogenesis positively through Rho B-mediated F-actin rearrangement.