[Postoperative effect analysis of different surgical techniques used in facial nerve reconstruction].

Objective:To investigate the factors and efficacy of different surgical techniques used in facial nerve（FN） reconstruction. Methods:A retrospective analysis was conducted on 24 patients who underwent facial nerve reconstruction surgery in our department from January 2016 to January 2021. The duration of total facial nerve paralysis was less than 18 months. The study included 5 surgical techniques, including 6 cases of FN anastomosis（Group A）, 5 cases of FN grafting（sural nerve or great auricular nerve）（Group B）, 5 cases of side-to-end facial-hypoglossal nerve anastomosis（Group C）, 4 cases of side-to-end FN grafting（sural nerve or great auricular nerve） hypoglossal nerve anastomosis（Group D）, and 4 cases of dual nerve reanimation（Group E）. The postoperative follow-up period was ≥1 year. Results:The HB-Ⅲ level of FN function at 1 year after surgery was 83.3%（5/6） in group A, 60.0%（3/5） in group B, 40.0%（2/5） in group C, 25.0%（1/4） in group D, and 50.0%（2/4） in group E. In patients without multiple FN repair, the incidence of synkinesis was 15.0%（3/20）, while no cases of synkinesis were observed in patients with dual nerve reanimation. The patients who underwent hypoglossal-facial side-to-end anastomosis showed no hypoglossal nerve dysfunction. Conclusion:Different FN repair techniques result in varying postoperative FN function recovery, as personalized repair should be managed. Among the various techniques, FN end-to-end anastomosis after FN transposition is recommended as to reduce the number of anastomotic stoma, while hypoglossal-facial side-to-end anastomosis is advocated as to prevent postoperative hypoglossal nerve dysfunction. Additionally, dual nerve repair can effectively improve smile symmetry and reduce synkinesis, which enhances patients' quality.

Impact of inner ear malformation and cochlear nerve deficiency on the development of auditory-language network in children with profound sensorineural hearing loss.

Profound congenital sensorineural hearing loss (SNHL) prevents children from developing spoken language. Cochlear implantation and auditory brainstem implantation can provide partial hearing sensation, but language development outcomes can vary, particularly for patients with inner ear malformations and/or cochlear nerve deficiency (IEM&CND). Currently, the peripheral auditory structure is evaluated through visual inspection of clinical imaging, but this method is insufficient for surgical planning and prognosis. The central auditory pathway is also challenging to examine in vivo due to its delicate subcortical structures. Previous attempts to locate subcortical auditory nuclei using fMRI responses to sounds are not applicable to patients with profound hearing loss as no auditory brainstem responses can be detected in these individuals, making it impossible to capture corresponding blood oxygen signals in fMRI. In this study, we developed a new pipeline for mapping the auditory pathway using structural and diffusional MRI. We used a fixel-based approach to investigate the structural development of the auditory-language network for profound SNHL children with normal peripheral structure and those with IEM&CND under 6 years old. Our findings indicate that the language pathway is more sensitive to peripheral auditory condition than the central auditory pathway, highlighting the importance of early intervention for profound SNHL children to provide timely speech inputs. We also propose a comprehensive pre-surgical evaluation extending from the cochlea to the auditory-language network, showing significant correlations between age, gender, Cn.VIII median contrast value, and the language network with post-implant qualitative outcomes.

Differentiation of geniculate ganglion venous malformation from schwannoma: dynamic T1-weighted imaging provides unique diagnostic value.

OBJECTIVE: To distinguish geniculate ganglion venous malformation (GGVM) from schwannoma (GGS) by using high-resolution CT (HRCT), routine MRI, and dynamic T1-weighted imaging (T1WI) characteristics. METHODS: Surgically confirmed GGVMs and GGSs between 2016 and 2021 were retrospectively included. Preoperative HRCT, routine MR, and dynamic T1WI were performed on all patients. Clinical data, imaging characteristics including lesion size, involvement of facial nerve (FN), signal intensity, enhancement pattern on dynamic T1WI, and bone destruction on HRCT were evaluated. Logistic regression model was developed to identify independent factors for GGVMs, and the diagnostic performance was accessed by receiving operative curve (ROC) analysis. Histological characteristics were explored for both GGVMs and GGSs. RESULTS: Twenty GGVMs and 23 GGSs with mean age of 31 were included. On dynamic T1WI, 18 GGVMs (18/20) showed "pattern A" enhancement (a progressive filling enhancement), while all 23 GGSs showed "pattern B" enhancement (a gradual whole-lesion enhancement) (p < 0.001). Thirteen GGVMs (13/20) showed the "honeycomb" sign whereas all GGS (23/23) showed extensive bone changes on HRCT (p < 0.001). Lesion size, involvement of FN segment, signal intensity on non-contrast T1WI and T2-weighted imaging (T2WI), and homogeneity on enhanced T1WI were obviously differed between two lesions (p < 0.001, p = 0.002, p < 0.001, p = 0.01, p = 0.02, respectively). Regression model showed the "honeycomb" sign and "pattern A" enhancement were independent risk factors. Histologically, GGVM was characterized by interwoven dilated and tortuous veins, while GGS was characterized by abundant spindle cells with dense arterioles or capillaries. CONCLUSIONS: The "honeycomb" sign on HRCT and "pattern A" enhancement on dynamic T1WI are the most promising imaging characteristics for differentiating GGVM from GGS. CLINICAL RELEVANCE STATEMENT: The characteristic sign and enhancement pattern on HRCT and dynamic T1-weighted imaging allow preoperative differentiation of geniculate ganglion venous malformation and schwannoma feasible, which will improve clinical management and benefit patient prognosis. KEY POINTS: • The "honeycomb" sign on HRCT is a reliable finding to differentiate GGVM from GGS. • GGVM typically shows "pattern A" enhancement (focal enhancement of the tumor on early dynamic T1WI, followed by progressive contrast filling of the tumor in the delayed phase), while "pattern B" enhancement (gradual heterogeneous or homogeneous enhancement of the whole lesion) is observed in GGS on dynamic T1WI.

Synergistic Effect of Erastin Combined with Nutlin-3 on Vestibular Schwannoma Cells as p53 Modulates Erastin-Induced Ferroptosis Response.

Vestibular schwannoma (VS) is a rare neurotology neoplasm that results in partial neurological defects. As we know, a comprehensive understanding of basic mechanisms and targeted therapy is vital for disease management. In VS, p53 has been proved to suppress tumor progression via a cooperative with the key protein, merlin, as well as regulation of the cell cycle. However, there are more potential mechanisms of p53 in VS needed to exploit. First, via genome-wide RNA expression analysis, we identified differentially expressed genes in VS compared with normal nerves, and then, bioinformatics analyses were used to analyze these differential expression data and suggested a high level of enrichment of cysteine and glutathione metabolism pathways in VS. Meanwhile, we observed a downregulation of SLC7A11/xCT, a component of the cystine/glutamate antiporter (also known as system xc -) involved in cystine uptake. Next, for a deeper study, our group extracted tumor cells from vestibular schwannoma tissues and established two immortalized cell lines named JEI-001 and JEI-002. Secondly, in our established cells, we demonstrated that ferroptosis participated in erastin-induced growth inhibition. As a novel cell death process, ferroptosis driven by iron-mediated lipid reactive oxygen species (lipid ROS), as well as cysteine and glutathione metabolism. Furthermore, ferroptosis contributes to the inhibitory effects of tumor suppressor p53. Here, we show that p53 sensitizes schwannoma cells to ferroptosis by repressing expression of SLC7A11/xCT. Finally, erastin combined with Nutlin-3, which s to p53 activation, triggered antitumor effects of ferroptosis on the growth of schwannoma cells in vitro. These findings present potential mechanism of p53 in schwannomas and raise the possibility of treatment strategies directed against this pathogenesis.

Endoscopic transcanal facial nerve decompression in Bell's palsy: A pilot study.

PURPOSE: To explore the surgical effects of endoscopic facial nerve decompression in Bell's palsy. MATERIALS AND METHODS: This retrospective study included 15 patients with Bell's palsy. All had grade VI (House-Brackmann grading system) complete unilateral facial paralysis before surgery and a >95% reduction in amplitude on electroneurography testing compared to the unaffected side. Their MRI results indicated perineural edema in the geniculate ganglion area. Endoscopic decompression surgery was performed soon after they presented at our hospital. The time between onset of facial paralysis and surgery ranged from 25 to 93 days. All patients had no relevant surgical history or ear diseases. RESULTS: At 1-year follow-up, 13 of the 15 (87%) patients had recovered to normal or near-normal facial function (House-Brackmann grade I-II), and all patients had reached House-Brackmann grade III or lower facial function. No obvious air-bone gap or sensorineural hearing loss occurred after surgery, and there were no severe complications or synkinesis. CONCLUSIONS: Endoscopic transcanal facial nerve decompression provides a less traumatic and improved exposure of the geniculate ganglion, and may also help prevent permanent severe facial sequela. Results of intraoperative facial nerve stimulation may be related to the length of time required for recovery. The optimal time of surgery after onset of paralysis needs to be investigated further, to identify a post-drug surgical therapy which may be more acceptable for patients. Patients' response to conservative treatments should be assessed as soon as possible so as not to delay surgery.

Detection and Functional Verification of Noncanonical Splice Site Mutations in Hereditary Deafness.

Splice site mutations contribute to a significant portion of the genetic causes for mendelian disorders including deafness. By next-generation sequencing of 4 multiplex, autosomal dominant families and 2 simplex, autosomal recessive families with hereditary deafness, we identified a variety of candidate pathogenic variants in noncanonical splice sites of known deafness genes, which include c.1616+3A > T and c.580G > A in EYA4, c.322-57_322-8del in PAX3, c.991-15_991-13del in DFNA5, c.6087-3T > G in PTPRQ and c.164+5G > A in USH1G. All six variants were predicted to affect the RNA splicing by at least one of the computational tools Human Splicing Finder, NNSPLICE and NetGene2. Phenotypic segregation of the variants was confirmed in all families and is consistent with previously reported genotype-phenotype correlations of the corresponding genes. Minigene analysis showed that those splicing site variants likely have various negative impact including exon-skipping (c.1616+3A > T and c.580G > A in EYA4, c.991-15_991-13del in DFNA5), intron retention (c.322-57_322-8del in PAX3), exon skipping and intron retention (c.6087-3T > G in PTPRQ) and shortening of exon (c.164+5G > A in USH1G). Our study showed that the cryptic, noncanonical splice site mutations may play an important role in the molecular etiology of hereditary deafness, whose diagnosis can be facilitated by modified filtering criteria for the next-generation sequencing data, functional verification, as well as segregation, bioinformatics, and genotype-phenotype correlation analysis.

Intratympanic Lipopolysaccharide Elevates Systemic Fluorescent Gentamicin Uptake in the Cochlea.

OBJECTIVES/HYPOTHESIS: Lipopolysaccharide (LPS), a key component of bacterial endotoxins, activates macrophages and triggers the release of inflammatory cytokines in mammalian tissues. Recent studies have shown that intratympanic injection of LPS simulates acute otitis media (AOM) and results in morphological and functional changes in the inner ear. Here we established an AOM mouse model with LPS to investigate the uptake of ototoxic gentamicin in the inner ear, and elucidated the underlying mechanism by focusing on cochlear inflammation as a result of AOM. STUDY DESIGN: Preclinical rodent animal model. METHODS: Fluorescently tagged gentamicin (GTTR) was systemically administered to mice with AOM. Iba1-positive macrophage morphology and inner ear cytokine profile were evaluated by immunofluorescence technique and a mouse cytokine array kit, respectively. RESULTS: We observed characteristic symptoms of AOM in the LPS-treated ears with elevated hearing thresholds indicating a conductive hearing loss. More importantly, the LPS-induced AOM activated cochlear inflammatory responses, manifested by macrophage infiltration, particularly in the organ of Corti and the spiral ligament, in addition to the up-regulation of proinflammatory cytokines. Meanwhile, GTTR uptake in the stria vascularis and sensory hair cells from all the LPS-treated ears was significantly enhanced at 24, 48, and 72-hour post-treatment, as the most prominent enhancement was observed in the 48-hour group. CONCLUSION: In summary, this study suggests that the pathological cochlea is more susceptible to ototoxic drugs, including aminoglycosides, and justified the clinical concern of aminoglycoside ototoxicity in the AOM treatment. Laryngoscope, 131:E2573-E2582, 2021.

Identification and Characterization of a Cryptic Genomic Deletion-Insertion in EYA1 Associated with Branchio-Otic Syndrome.

Branchio-oto-renal spectrum disorder (BORSD) is characterized by hearing loss accompanied by ear malformations, branchial cysts, and fistulae, with (branchio-oto-renal syndrome (BORS)) or without renal abnormalities (BOS (branchio-otic syndrome)). As the most common causative gene for BORSD, dominant mutations in EYA1 are responsible for approximately 40% of the cases. In a sporadic deaf patient diagnosed as BOS, we identified an apparent heterozygous genomic deletion spanning the first four coding exons and one 5' noncoding exon of EYA1 by targeted next-generation sequencing of 406 known deafness genes. Real-time PCR at multiple regions of EYA1 confirmed the existence of this genomic deletion and extended its 5' boundary beyond the 5'-UTR. Whole genome sequencing subsequently located the 5' and 3' breakpoints to 19268 bp upstream to the ATG initiation codon and 3180 bp downstream to exon 5. PCR amplification across the breakpoints in both the patient and his parents showed that the genomic alteration occurred de novo. Sanger sequencing of this PCR product revealed that it is in fact a GRCh38/hg38:chr8:g.71318554_71374171delinsTGCC genomic deletion-insertion. Our results showed that the genomic variant is responsible for the hearing loss associated with BOS and provided an example for deciphering such cryptic genomic alterations following pipelines of comprehensive exome/genome sequencing and designed verification.

Diagnostic value of dynamic contrast-enhanced magnetic resonance imaging in Bell's palsy.

BACKGROUND: Bell's palsy (BP) is the most common form of acute facial nerve disorder and is characterized by rapid onset peripheral facial palsy of unknown etiology. PURPOSE: To explore the diagnostic value of dynamic contrast-enhanced (DCE) magnetic resonance imagine (MRI) in patients with BP particularly in involved segments. MATERIAL AND METHODS: A retrospective analysis was performed on the patients with BP who underwent routine MRI examinations and volumetric interpolated breath-hold examination (VIBE) sequence-based DCE-MRI before surgery in our department from January 2015 to July 2020. DCE-MRI data postprocessing was performed on Siemens Workstation Extended MR Work Space 2.6.3.5. Statistical analyses were performed using SPSS®v.19.0. The inter-observer reliability was evaluated with kappa identity test and McNemar's test. RESULTS: Twenty-three patients were included. On conventional contrast-enhanced MRI, the two observers were inconsistent in their diagnosis of lesion segments of facial nerve (Kappa 0.426, P = 0.009). Compared to the results of the surgery, the diagnostic consistency of both observers was general (Kappa 0.476, P < 0.001 and Kappa 0.430, P < 0.001, respectively). The diagnostic results of DCE-MRI for lesion segments of the facial nerve were consistent between the two observers (Kappa 0.929, P < 0.001). Compared to the results of the surgery, the diagnostic consistency of both observers was good (Kappa 0.753, P < 0.001 and Kappa 0.731, P < 0.001, respectively). CONCLUSION: Compared to conventional MRI, DCE-MRI has good stability and repeatability in the diagnosis of the lesion segments of the facial nerve as well as a good specificity and accuracy.

Age-dependent copy number variations of TP53 tumour suppressor gene associated with altered phosphorylation status of p53 protein in sporadic schwannomas.

PURPOSE: Point mutations of TP53 tumour suppressor are very rare in schwannomas. We aim to characterize the frequency of exonic copy-number changes of the gene in the tumour and to examine the association between TP53 alterations, phosphorylation status of p53 protein and clinical phenotypes. METHODS: The alterations of TP53 were screened by a combination of Sanger sequencing and multiplex ligation-dependent probe amplification (MLPA) in a total of 44 vestibular schwannomas. The mutation index (MI) in a tumour was defined as the number of exons mutated/ the number of exons tested. Phosphorylation status of p53 protein was investigated by immunoblotting and immunofluorescence. RESULTS: MLPA analysis showed single and multi-exon deletion mutations of TP53 in 65.7% of the cases. Comparisons of clinical features between mutated and non-mutated patients established an association of TP53 mutations with progressive phenotypes, including an earlier formation and a larger tumour. In addition, there were significant correlations between MI and both patients' age and tumour size. The Ser 392 phosphorylation level of p53 varied among tumours, and correlation analysis revealed an age-dependent phosphorylation pattern. The majority of tumours with hyperphosphorylated p53 were from mutated and young patients, suggesting an association of Ser392 phosphorylation with the mutational status of TP53 involved in the acceleration of tumour growth in young individuals. Moreover, Ser 392 phosphorylation contributed to a nuclear accumulation of p53 in schwannona cultures with TP53 mutation. CONCLUSIONS: An interplay between the mutation status of TP53, phosphorylation patterns and tumour behaviors might be established in the disease.

A homozygous MITF mutation leads to familial Waardenburg syndrome type 4.

Waardenburg syndrome (WS) is a genetic disorder characterized by hearing loss and pigmentary abnormalities with variable penetrance. Though heterozygous mutations in MITF are a major cause for Waardenburg syndrome type 2 (WS2), homozygous mutations in this gene and the associated phenotype have been rarely characterized. In this study, we identified a novel p.R223H mutation in MITF in a Chinese Han family with variable WS features. Both parents carried a heterozygous p.R223H mutation. They had normal hearing, and premature greying of the hair is their only pigmentary abnormality. In contrast, their two children both carried a homozygous p.R223H mutation and had classic WS features including profound hearing loss, heterochromia irides and marked pigmentary abnormalities in hair and skin. Interestingly, the two affected children also have persistent chronic constipation since the neonatal period, symptoms suggestive of Waardenburg syndrome type 4 (WS4). Our study revealed a likely association between homozygous mutations in MITF and WS4, which implies a dosage effect for the underlying pathogenesis mechanism.

Postnatal Development of Microglia-Like Cells in Mouse Cochlea.

Microglial cells are involved in surveillance and cleaning of the central nervous system. Recently, microglial-like cells (MLC) have been found in an adult cochlea and investigated for their role in cochlear inflammation. The presence and potential roles of MLCs during the development of the cochlea, however, remain unclear. In this study, immunostaining was performed using the MLC-specific marker IBA1 to characterize the presence, distribution, and morphology of MLCs in the developing cochlea. From P0 to P14, MLCs were present in a variety of cochlear regions including the modiolus, spiral lamina, spiral ganglion, spiral ligament, and the organ of Corti. Interestingly, the overall number of MLCs in a mouse cochlea steadily increased since P0, peaks at P5, then gradually decreased from P5 to P14. In the spiral ligament, the distribution of the MLCs trends to shift from the type I/II fibrocyte-rich regions to the type III/IV fibrocyte-rich regions during the course of cochlear development, accompanied by the morphological changes of MLCs from the amoeboid, activated form to the ramified, quiescent form. Our results suggested that MLCs experience drastic morphological and distributional changes during postnatal cochlear development, which may play a role in the maturing and remodeling of the cochlea.

Long-Term Hearing Preservation Outcomes for Small Vestibular Schwannomas: Retrosigmoid Removal Versus Observation.

OBJECTIVE: Management of small vestibular schwannomas (VSs) consists of three options: serial observation, radiosurgery, and microsurgery. The authors reported the long-term hearing outcomes after retrosigmoid tumor removal in 110 patients and hearing follow-up outcomes in 160 serial observation patients with small VSs to explore the appropriate management strategy and predictive factors of hearing preservation for small VSs. STUDY DESIGN: Retrospective study. SETTING: Tertiary referral center. PATIENTS: In this study, 110 patients with small VS (purely intracanalicular/cerebellopontine angle tumor ≤15 mm) during a 15-year period, from January 2001 to December 2015, were candidates for hearing preservation surgery through retrosigmoid approach, while 160 patients were candidates for serial observation. The main outcome measure was preservation of hearing under different hearing levels, assessed with the classification of American Academy of Otolaryngology-Head and Neck Surgery. RESULTS: Preoperative hearing levels of the 110 study patients were Class A in 49 patients, Class B in 43 patients, and Class C in 18 patients. In all surgery patients (n = 110), 97.3% (107/110) patients maintained the same level during postoperative follow-up (mean follow-up time was 49.1 ±â€Š28.2 mo) and 86 (78.2%) had complete radiologic and audiometric data at least 4 years follow-up for review. In the 4 years follow-up surgery group (n = 86), postoperative hearing levels were Class A, B, C, and D for 22, 11, 18, and 35 patients, and postoperative rates of preservation of serviceable and useful hearing were 59.3% (51/86) and 47.1% (33/70), respectively. In serial observation group, mean follow-up time was 35.2 ±â€Š33.1 months; mean tumor size at presentation was 8.6 ±â€Š4.3 mm; overall mean tumor growth rate was 1.08 ±â€Š2.3 mm/yr; serviceable hearing preservation rate of 98 patients was 54.1% (53/98) at the 5-year end point and 48.7% (37/76) at the 7-year end point. CONCLUSION: Tumor removal should be the first treatment option for patients with small VSs and preserved hearing, especially for young patients with good hearing; retrosigmoid approach is an effective and safe approach for small VSs removal with excellent functional outcomes; better preoperative hearing predicted a higher rate of postoperative hearing preservation; patients without fundal extension were more likely to achieve hearing preservation than those with fundal extension, but no difference had been detected when retrosigmoid removal assisted with endoscope was performed; patients with small tumors originating from SVN were more likely to achieve hearing preservation compared with those with IVN-originating tumors.

BoneBridge implantation in patients with single-sided deafness resulting from vestibular schwannoma resection: objective and subjective benefit evaluations.

BACKGROUND: The BoneBridge could rehabilitate hearing for patients with single-sided deafness (SSD). OBJECTIVES: To evaluate the objective and subjective benefits of BoneBridge implantation in patients after vestibular Schwannoma resection and to explore the factors affecting the benefits. MATERIAL AND METHODS: We prospectively enrolled all 15 patients implanted with BoneBridge after VS resection from January to June 2017. The primary outcome was the ability to hear in noisy conditions. The secondary outcomes were the soft-band BoneBridge try-on rate, the frequency of BB use, the sound source localization test result, and questionnaire measures of quality of life (QoL). RESULTS: Patients showed better speech recognition ability in the presence of noise with the BoneBridge. The BoneBridge provided no help in sound localization, although most patients reported subjective sound localization benefits. The results of QoL questionnaires showed significant satisfaction with BoneBridge implantation. The unilateral hearing deprivation duration and high education levels had significant impacts on the subjective benefits of patients. CONCLUSIONS: The BoneBridge could improve speech recognition performance in complex auditory backgrounds, as well as QoL, especially in patients with short unilateral hearing deprivation durations and high education levels. SIGNIFICANCE: The BoneBridge is an effective hearing aid for single-sided deafness patients after VS removal.

Genetic analysis of a Chinese family with members affected with Usher syndrome type II and Waardenburg syndrome type IV.

AIMS: The purpose of this study was to identify the genetic causes of a family presenting with multiple symptoms overlapping Usher syndrome type II (USH2) and Waardenburg syndrome type IV (WS4). METHODS: Targeted next-generation sequencing including the exon and flanking intron sequences of 79 deafness genes was performed on the proband. Co-segregation of the disease phenotype and the detected variants were confirmed in all family members by PCR amplification and Sanger sequencing. RESULTS: The affected members of this family had two different recessive disorders, USH2 and WS4. By targeted next-generation sequencing, we identified that USH2 was caused by a novel missense mutation, p.V4907D in GPR98; whereas WS4 due to p.V185M in EDNRB. This is the first report of homozygous p.V185M mutation in EDNRB in patient with WS4. CONCLUSION: This study reported a Chinese family with multiple independent and overlapping phenotypes. In condition, molecular level analysis was efficient to identify the causative variant p.V4907D in GPR98 and p.V185M in EDNRB, also was helpful to confirm the clinical diagnosis of USH2 and WS4.

A dominant variant in DMXL2 is linked to nonsyndromic hearing loss.

PURPOSE: To explore the genetic etiology of deafness in a dominant family with late-onset, progressive, nonsyndromic hearing loss. METHODS: Genome-wide linkage analysis was performed for 21 family members. Candidate pathogenic variants were identified by whole-exome sequencing of selected family members and confirmed by Sanger sequencing of all family members. Cochlear expression of Dmxl2 was investigated by reverse-transcription polymerase chain reaction (RT-PCR) and immunostaining of the organ of Corti from mice. RESULTS: The causative gene was mapped to a 9.68-Mb candidate region on chromosome 15q21.2 (maximum logarithm of the odds score = 4.03) that contained no previously described deafness genes. Whole-exome sequencing identified heterozygous c.7250G>A (p.Arg2417His) in DMXL2 as the only candidate pathogenic variant segregating the hearing loss. In mouse cochlea, expression of DMXL2 was restricted to the hair cells and the spiral ganglion neurons. CONCLUSION: Our data indicated that the p.Arg2417His variant in DMXL2 is associated with dominant, nonsyndromic hearing loss and suggested an important role of DMXL2 in inner ear function.Genet Med advance online publication 22 September 2016.

A 7666-bp genomic deletion is frequent in Chinese Han deaf patients with non-syndromic enlarged vestibular aqueduct but without bi-allelic SLC26A4 mutations.

OBJECTIVES: To investigate the genetic cause of the patients with non-syndromic enlarged vestibular aqueduct (EVA) but without bi-allelic SLC26A4 mutations. METHODS: Presence of a homozygous genomic deletion was detected in a Chinese Han deaf patient (D1467-1) who failed to amplify the first three exons of SLC26A4. The breakpoints of the deletion were fine-mapped and revealed by PCR amplification and sequencing. This deletion was subsequently screened in 22 Chinese Han EVA probands with mono-allelic SLC26A4 mutations. The possible founder effect of the newly identified genomic deletion was evaluated by haplotype analysis. RESULTS: A homozygous c.-2071_307+3801del7666 deletion of SLC26A4 was identified in patient D1467-1. This novel genomic deletion was subsequently identified in 18% (4/22) of the Chinese Han EVA probands with mono-allelic SLC26A4 mutations. Haplotype analysis showed that this genomic deletion is likely a founder mutation in Chinese Hans. CONCLUSION: Our results suggested that the cryptic c.-2071_307+3801del7666 deletion of SLC26A4 is relatively frequent in Chinese Han non-syndromic EVA patients without bi-allelic SLC26A4 mutations. Screening of this genomic deletion should be incorporated into the routine DNA testing of SLC26A4 in Chinese Hans.

Mutation in PCDH15 may modify the phenotypic expression of the 7511T>C mutation in MT-TS1 in a Chinese Han family with maternally inherited nonsyndromic hearing loss.

OBJECTIVES: Mutations in MT-TS1 have been found to be associated with nonsyndromic sensorineural hearing loss (SNHL). PCDH15 codes for protocadherin-15, a member of the cadherin superfamily of calcium-dependent cell-cell adhesion molecules. In this study, we analyzed the correlation of both MT-TS1 and PCDH15 mutations in a Chinese Han family segregating maternally inherited nonsyndromic SNHL. METHODS: We ascertained a Chinese Han family segregating maternally inherited nonsyndromic sensorineural hearing loss. Eight of 10 maternal members in this family exhibited late-onset, progressive hearing impairment. Mutation screening of 79 known deafness genes was performed for the proband by targeted next-generation sequencing. RESULTS: A total of 651 variants were detected in this individual. Among them, a homoplasmic 7511T>C variant in MT-TS1, the mitochondrial tRNA (Ser(UCN)) gene, and a heterozygous p.Asp1010Gly variant in PCDH15 were more likely to be pathogenic. Consistent with the matrilineal inheritance with reduced penetrance, the 7511T>C variant in MT-TS1 was found in all 10 maternal members and an additional heterozygous p.Asp1010Gly variant in PCDH15 cosegregated with the hearing loss in this family. CONCLUSION: Our results suggested that the PCDH15 p.Asp1010Gly variant probably modified the phenotypic expression of the 7511T>C mutation in MT-TS1.

Mono-allelic mutations of SLC26A4 is over-presented in deaf patients with non-syndromic enlarged vestibular aqueduct.

OBJECTIVES: Recessive mutations of SLC26A4 are the major cause of hearing impairment associated with enlarged vestibular aqueduct (EVA). In a significant percentage of non-syndromic EVA patients, however, only mono-allelic mutations of SLC26A4 can be identified. In this study, we aimed to evaluate whether presence of mono-allelic mutations of SLC26A4 in those patients was coincidental or etiologically associated with the disorder. METHODS: The exons and flanking splicing sites of SLC26A4 were sequenced in 150 Chinese Han deaf probands with non-syndromic EVA. c.919-2A >G and p.H723R, two frequent mutations of SLC26A4 in Chinese Hans, were screened by an allele-specific PCR-based array in 3056 ethnically-matched normal hearing controls. The frequency of mono-allelic c.919-2A >G and p.H723R mutations was determined in each group. The statistical significance of the difference was analyzed by Fisher's exact test. RESULTS: Bi-allelic, mono-allelic and no mutation of SLC26A4 were detected in 98 (65.3%), 18 (12%) and 34 (22.67%) deaf probands with non-syndromic EVA, respectively. The frequency of mono-allelic c.919-2A >G and p.H723R mutations were significantly higher in the 150 deaf probands with non-syndromic EVA (8.67%) than in the 3056 normal hearing controls (1.4%, P=1.8×10(-6)). CONCLUSION: Presence of mono-allelic mutations of SLC26A4 in non-syndromic EVA patients is etiologically associated with this disorder. Additional genetic or environmental causes may be present in those patients and demand further investigation and consideration during the genetic diagnosis and counseling.

Targeted next-generation sequencing in Uyghur families with non-syndromic sensorineural hearing loss.

The mutation spectrum of deafness genes may vary in different ethnical groups. In this study, we investigated the genetic etiology of nonsyndromic deafness in four consanguineous and two multiplex Uyghur families in which mutations in common deafness genes GJB2, SLC26A4 and MT-RNR1 were excluded. Targeted next-generation sequencing of 97 deafness genes was performed in the probands of each family. Novel pathogenic mutations were identified in four probands including the p.L416R/p.A438T compound heterozygous mutations in TMC1, the homozygous p.V1880E mutation in MYO7A, c.1238delT frameshifting deletion in PCDH15 and c.9690+1G>A splice site mutation in MYO15A. Co-segregation of the mutations and the deafness were confirmed within each family by Sanger sequencing. No pathogenic mutations were identified in one multiplex family and one consanguineous family. Our study provided a useful piece of information for the genetic etiology of deafness in Uyghurs.