Search Results (34)

Background/Objectives: A heterozygous mutation in the WFS1 gene is responsible for autosomal dominant non-syndromic hearing loss (DFNA6/14/38) and Wolfram-like syndrome, which is characterized by bilateral sensorineural hearing loss with optic atrophy and/or diabetes mellitus. However, detailed clinical features for the patients with the heterozygous p.A684V variant remain unknown. Methods: We report the clinical details of 14 cases with a heterozygous p.A684V variant in the WFS1 gene identified from target resequencing analysis of 63 previously reported deafness genes by next-generation sequencing of 15,684 hearing loss patients (mean age 27.5 ± 23.1 years old, 6574 male, 8612 female and 498 for whom information was unavailable). Results: Among the 14 patients from 13 families with the p.A684V variant, nine were sporadic cases. In addition, we confirmed de novo occurrence of this variant in seven families. This result strongly supports the notion that this variant was located on a mutational hotspot. When comparing previously reported cases of autosomal dominant WFS1 gene-associated hearing loss, most of the patients in this study showed severe-to-profound bilateral sensorineural hearing loss (genotype–phenotype correlation). Two patients had optic atrophy, while the others did not have any other complications. Conclusions: The identified heterozygous p.A684V variant appears to be a hotspot mutation and likely to cause severe-to-profound hearing loss in early childhood. Cochlear implantation is considered favorable in cases of hearing impairment due to this variant. Full article

Background: Mutations in Wolfram syndrome 1 (WFS1) cause Wolfram syndrome and autosomal dominant non-syndromic hearing loss DFNA6/14/38. To date, more than 300 pathogenic variants of WFS1 have been identified. Generally, the audiological phenotype of Wolfram syndrome or DFNA6/14/38 is characterized by low-frequency hearing loss; however, this phenotype is largely variable. Hence, there is a need to better understand the diversity in audiological and vestibular profiles associated with WFS1 variants, as this can have significant implications for diagnosis and management. This study aims to investigate the clinical characteristics, audiological phenotypes, and vestibular function in patients with DFNA6/14/38. Methods: Whole-exome or targeted deafness gene panel sequencing was performed to confirm the pathogenic variants in patients with genetic hearing loss. Results: We identified nine independent families with affected individuals who carried a heterozygous pathogenic variant of WFS1. The onset of hearing loss varied from the first to the fifth decade. On a pure-tone audiogram, hearing loss was symmetrical, and the severity ranged from mild to severe. Notably, either both low-frequency and high-frequency or all-frequency-specific hearing loss was observed. However, hearing loss was non-progressive in all types. In addition, vestibular impairment was identified in patients with DFNA6/14/38, indicating that impaired WFS1 may also affect the vestibular organs. Conclusions: Diverse audiological and vestibular profiles were observed in patients with pathogenic variants of WFS1. These findings highlight the importance of comprehensive audiological and vestibular assessments in patients with WFS1 mutations for accurate diagnosis and management. Full article

The PTPRQ gene has been identified as one of the genes responsible for non-syndromic sensorineural hearing loss (SNHL), and assigned as DFNA73 and DFNB84. To date, about 30 causative PTPRQ variants have been reported to cause SNHL. However, the detailed clinical features of PTPRQ-associated hearing loss (HL) remain unclear. In this study, 15,684 patients with SNHL were enrolled and genetic analysis was performed using massively parallel DNA sequencing (MPS) for 63 target deafness genes. We identified 17 possibly disease-causing PTPRQ variants in 13 Japanese patients, with 15 of the 17 variants regarded as novel. The majority of variants identified in this study were loss of function. Patients with PTPRQ-associated HL mostly showed congenital or childhood onset. Their hearing levels at high frequency deteriorated earlier than that at low frequency. The severity of HL progressed from moderate to severe or profound HL. Five patients with profound or severe HL received cochlear implantation, and the postoperative sound field threshold levels and discrimination scores were favorable. These findings will contribute to a greater understanding of the clinical features of PTPRQ-associated HL and may be relevant in clinical practice. Full article

Background: DFNA9 is a genetic disease of the inner ear, causing progressive bilateral sensorineural deafness and bilateral vestibulopathy (BV). In this study, DizzyQuest, a mobile vestibular diary, and the MOX accelerometer were combined to assess the daily life functional limitations and physical activity of patients with DFNA9 suffering from BV. These parameters might be appropriate as potential candidacy criteria and outcome measures for new therapeutic interventions for BV. Methods: Fifteen DFNA9 patients with BV and twelve age-matched healthy controls were included. The DizzyQuest was applied for six consecutive days, which assessed the participants’ extent of functional limitations, tiredness, types of activities performed during the day, and type of activity during which the participant felt most limited. The MOX accelerometer was worn during the same six days of DizzyQuest use, measuring the participants intensity and type of physical activity. Mixed-effects linear and logistic regression analyses were performed to compare the DFNA9 patients and control group. Results: DFNA9 patients with BV felt significantly more limited in activities during the day compared to the age-matched controls, especially in social participation (p < 0.005). However, these reported limitations did not cause adjustment in the types of activities and did not reduce the intensity or type of physical activity measured with accelerometry. In addition, no relationships were found between self-reported functional limitations and physical activity. Conclusions: This study demonstrated that self-reported functional limitations are significantly higher among DFNA9 patients with BV. As a result, these limitations might be considered as part of the candidacy criteria or outcome measures for therapeutic interventions. In addition, the intensity or type of physical activity performed during the day need to be addressed more specifically in future research. Full article

COCH (coagulation factor C homology) is one of the most frequently mutated genes of autosomal dominant non-syndromic hearing loss. Variants in COCH could cause DFNA9, which is characterized by late-onset hearing loss with variable degrees of vestibular dysfunction. In this study, we report a Chinese family with a novel COCH variant (c.1687delA) causing p.D544Vfs*3 in the cochlin. Comprehensive audiometric tests and vestibular function assessments were taken to acquire the phenotypic profile of the subjects. Next-generation sequencing was conducted and segregation analysis was carried out using Sanger sequencing. The proband presented mild vestibular symptoms and normal functional assessment results in almost every test, while the variant co-segregated with hearing impairment in the pedigree. The variant was located beyond the vWFA2 domain, which was predicted to affect the post-translational cleavage of the cochlin via molecular modeling analysis. Notably, in the overexpressing study, by transient transfecting the HEK 293T cells, we found that the p.D544Vfs*3 variant increased the formation of multimeric cochlin. Our result enriched the spectrum of DFNA9-linked pathological COCH variants and suggested that variants, causative of cochlin multimerization, could be related to DFNA9 with sensorineural hearing loss rather than serious vestibular symptoms. Full article

One of the most common forms of genetic deafness has been predominantly associated with pathogenic variants in the GJB2 gene, encoding transmembrane protein connexin 26 (Cx26). The Cx26 molecule consists of an N-terminal domain (NT), four transmembrane domains (TM1–TM4), two extracellular loops (EL1 and EL2), a cytoplasmic loop, and a C-terminus (CT). Pathogenic variants in the GJB2 gene, resulting in amino acid substitutions scattered across the Cx26 domains, lead to a variety of clinical outcomes, including the most common non-syndromic autosomal recessive deafness (DFNB1A), autosomal dominant deafness (DFNA3A), as well as syndromic forms combining hearing loss and skin disorders. However, for rare and poorly documented variants, information on the mode of inheritance is often lacking. Numerous in vitro studies have been conducted to elucidate the functional consequences of pathogenic GJB2 variants leading to amino acid substitutions in different domains of Cx26 protein. In this work, we summarized all available data on a mode of inheritance of pathogenic GJB2 variants leading to amino acid substitutions and reviewed published information on their functional effects, with an emphasis on their localization in certain Cx26 domains. Full article

Foliar diseases caused by Stemphylium and Colletotrichum species are among the major biotic factors limiting Welsh onion production in Taiwan. Owing to concerns about the environment and the development of pathogen resistance to existing fungicides, biological control using endophytes is emerging as an eco-friendly alternative to chemical control. The aim of the present study was to isolate endophytes from healthy Welsh onion leaves and investigate their antagonistic potential against the major phytopathogenic fungi associated with Welsh onion plants in Taiwan. A total of 109 bacterial and 31 fungal strains were isolated from healthy Welsh onion leaves and assigned to 16 bacterial and nine fungal genera using morphological and molecular characterization based on DNA sequence data obtained from nuclear internal transcribed spacer (nrITS) (fungi) and 16S rRNA (bacteria). Evaluation of these endophytic isolates for biocontrol activity against leaf blight pathogens Colletotrichum spaethianum strain SX15-2 and Stemphylium vesicarium strain SX20-2 by dual culture assay and greenhouse experiments resulted in the identification of two bacterial isolates (GFB08 and LFB28) and two fungal isolates (GFF06 and GFF08) as promising antagonists to leaf blight pathogens. Among the four selected isolates, Bacillus strain GFB08 exhibited the highest disease control in the greenhouse study. Therefore, Bacillus strain GFB08 was further evaluated to understand the mechanism underlying its biocontrol efficacy. A phylogenetic analysis based on six genes identified Bacillus strain GFB08 as B. velezensis. The presence of antimicrobial peptide genes (baer, bamC, bmyB, dfnA, fenD, ituC, mlna, and srfAA) and the secretion of several cell wall degrading enzymes (CWDEs), including cellulase and protease, confirmed the antifungal nature of B. velezensis strain GFB08. Leaf blight disease suppression by preventive and curative assays indicated that B. velezensis strain GFB08 has preventive efficacy on C. spaethianum strain SX15-2 and both preventive and curative efficacy on S. vesicarium strain SX20-2. Overall, the current study revealed that healthy Welsh onion leaves harbour diverse bacterial and fungal endophytes, among which the endophytic bacterial strain, B. velezensis strain GFB08, could potentially be used as a biocontrol agent to manage the leaf blight diseases of Welsh onion in Taiwan. Full article

Autosomal dominant non-syndromic hearing loss (HL) typically occurs when only one dominant allele within the disease gene is sufficient to express the phenotype. Therefore, most patients diagnosed with autosomal dominant non-syndromic HL have a hearing-impaired parent, although de novo mutations should be considered in all cases of negative family history. To date, more than 50 genes and 80 loci have been identified for autosomal dominant non-syndromic HL. DFNA22 (MYO6 gene), DFNA8/12 (TECTA gene), DFNA20/26 (ACTG1 gene), DFNA6/14/38 (WFS1 gene), DFNA15 (POU4F3 gene), DFNA2A (KCNQ4 gene), and DFNA10 (EYA4 gene) are some of the most common forms of autosomal dominant non-syndromic HL. The characteristics of autosomal dominant non-syndromic HL are heterogenous. However, in most cases, HL tends to be bilateral, post-lingual in onset (childhood to early adulthood), high-frequency (sloping audiometric configuration), progressive, and variable in severity (mild to profound degree). DFNA1 (DIAPH1 gene) and DFNA6/14/38 (WFS1 gene) are the most common forms of autosomal dominant non-syndromic HL affecting low frequencies, while DFNA16 (unknown gene) is characterized by fluctuating HL. A long audiological follow-up is of paramount importance to identify hearing threshold deteriorations early and ensure prompt treatment with hearing aids or cochlear implants. Full article

The aim of this study is to contribute to a better description of the genotypic and phenotypic spectrum of DFNA6/14/38 and aid in counseling future patients identified with this variant. Therefore, we describe the genotype and phenotype in a large Dutch–German family (W21-1472) with autosomal dominant non-syndromic, low-frequency sensorineural hearing loss (LFSNHL). Exome sequencing and targeted analysis of a hearing impairment gene panel were used to genetically screen the proband. Co-segregation of the identified variant with hearing loss was assessed by Sanger sequencing. The phenotypic evaluation consisted of anamnesis, clinical questionnaires, physical examination and examination of audiovestibular function. A novel likely pathogenic WFS1 variant (NM_006005.3:c.2512C>T p.(Pro838Ser)) was identified in the proband and found to co-segregate with LFSNHL, characteristic of DFNA6/14/38, in this family. The self-reported age of onset of hearing loss (HL) ranged from congenital to 50 years of age. In the young subjects, HL was demonstrated in early childhood. At all ages, an LFSNHL (0.25–2 kHz) of about 50–60 decibel hearing level (dB HL) was observed. HL in the higher frequencies showed inter-individual variability. The dizziness handicap inventory (DHI) was completed by eight affected subjects and indicated a moderate handicap in two of them (aged 77 and 70). Vestibular examinations (n = 4) showed abnormalities, particularly in otolith function. In conclusion, we identified a novel WFS1 variant that co-segregates with DFNA6/14/38 in this family. We found indications of mild vestibular dysfunction, although it is uncertain whether this is related to the identified WFS1 variant or is an incidental finding. We would like to emphasize that conventional neonatal hearing screening programs are not sensitive to HL in DFNA6/14/38 patients, because high-frequency hearing thresholds are initially preserved. Therefore, we suggest screening newborns in DFNA6/14/38 families with more frequency-specific methods. Full article

Hearing loss is the most common sensory deficit, affecting 466 million people worldwide. The vast and diverse genes involved reflect the complexity of auditory physiology, which requires the use of animal models in order to gain a fuller understanding. Among the loci with a yet-to-be validated gene is the DFNA58, in which ~200 Kb genomic duplication, including three protein-coding genes (PLEK, CNRIP1, and PPP3R1′s exon1), was found to segregate with autosomal dominant hearing loss. Through whole genome sequencing, the duplication was found to be in tandem and inserted in an intergenic region, without the disruption of the topological domains. Reanalysis of transcriptomes data studies (zebrafish and mouse), and RT-qPCR analysis of adult zebrafish target organs, in order to access their orthologues expression, highlighted promising results with Cnrip1a, corroborated by zebrafish in situ hybridization and immunofluorescence. Mouse data also suggested Cnrip1 as the best candidate for a relevant role in auditory physiology, and its importance in hearing seems to have remained conserved but the cell type exerting its function might have changed, from hair cells to spiral ganglion neurons. Full article

Previously, we reported the use of confocal Raman spectroscopy (CRS) as a novel non-invasive approach to determine drug disposition in the skin in vivo. Results obtained by CRS were found to correlate with data from the well-established in vitro permeation test (IVPT) model using human epidermis. However, these studies used simple vehicles comprising single solvents and binary or ternary solvent mixtures; to date, the utility of CRS for monitoring dermal absorption following application of complex marketed formulations has not been examined. In the present work, skin delivery of diclofenac sodium (DFNa) from two topical dermatological drug products, namely Diclac^® Lipogel 10 mg/g and Primofenac^® Emulsion gel 1%, was determined by IVPT and in vivo by both CRS and tape stripping (TS) methodologies under similar experimental conditions. The in vivo data were evaluated against the in vitro findings, and a direct comparison between CRS and TS was performed. Results from all methodologies showed that Diclac promoted significantly greater DFNa delivery to the skin (p < 0.05). The cumulative amounts of DFNa which permeated at 24 h in vitro for Diclac (86.5 ± 9.4 µg/cm²) were 3.6-fold greater than the corresponding amounts found for Primofenac (24.4 ± 2.7 µg/cm²). Additionally, total skin uptake of DFNa in vivo, estimated by the area under the depth profiles curves (AUC), or the signal intensity of the drug detected in the upper stratum corneum (SC) (4 µm) ranged from 3.5 to 3.6-fold greater for Diclac than for Primofenac. The shape of the distribution profiles and the depth of DFNa penetration to the SC estimated by CRS and TS were similar for the two methods. However, TS data indicated a 4.7-fold greater efficacy of Diclac relative to Primofenac, with corresponding total amounts of drug penetrated, 94.1 ± 22.6 µg and 20.2 ± 7.0 µg. The findings demonstrate that CRS is a methodology that is capable of distinguishing skin delivery of DFNa from different formulations. The results support the use of this approach for non-invasive evaluation of topical products in vivo. Future studies will examine additional formulations with more complex compositions and will use a wider range of drugs with different physicochemical properties. The non-invasive nature of CRS coupled with the ability to monitor drug permeation in real time offer significant advantages for testing and development of topical dermatological products. Full article

Deafness-associated genes KCNQ1 (also associated with heart diseases) and KCNQ4 (only associated with hearing loss) encode the homotetrameric voltage-gated potassium ion channels Kv7.1 and Kv7.4, respectively. To date, over 700 KCNQ1 and over 70 KCNQ4 variants have been identified in patients. The vast majority of these variants are inherited dominantly, and their pathogenicity is often explained by dominant-negative inhibition or haploinsufficiency. Our recent study unexpectedly identified cell-death-inducing cytotoxicity in several Kv7.1 and Kv7.4 variants. Elucidation of this cytotoxicity mechanism and identification of its modifiers (drugs) have great potential for aiding the development of a novel pharmacological strategy against many pathogenic KCNQ variants. The purpose of this review is to disseminate this emerging pathological role of Kv7 variants and to underscore the importance of experimentally characterizing disease-associated variants. Full article

Hearing relies on the proper functioning of auditory hair cells and on actin-based cytoskeletal structures. Diaphanous-related formins (DRFs) are evolutionarily conserved cytoskeletal proteins that regulate the nucleation of linear unbranched actin filaments. They play key roles during metazoan development, and they seem particularly pivotal for the correct physiology of the reproductive and auditory systems. Indeed, in Drosophila melanogaster, a single diaphanous (dia) gene is present, and mutants show sterility and impaired response to sound. Vertebrates, instead, have three orthologs of the diaphanous gene: DIAPH1, DIAPH2, and DIAPH3. In humans, defects in DIAPH1 and DIAPH3 have been associated with different types of hearing loss. In particular, heterozygous mutations in DIAPH1 are responsible for autosomal dominant deafness with or without thrombocytopenia (DFNA1, MIM #124900), whereas regulatory mutations inducing the overexpression of DIAPH3 cause autosomal dominant auditory neuropathy 1 (AUNA1, MIM #609129). Here, we provide an overview of the expression and function of DRFs in normal hearing and deafness. Full article

Autosomal dominant hearing loss (ADHL) manifests as an adult-onset disease or a progressive disease. MYO7A variants are associated with DFNA11, a subtype of ADHL. Here, we examined the role and genotype–phenotype correlation of MYO7A in ADHL. Enrolled families suspected of having post-lingual sensorineural hearing loss were selected for exome sequencing. Mutational alleles in MYO7A were identified according to ACMG guidelines. Segregation analysis was performed to examine whether pathogenic variants segregated with affected status of families. All identified pathogenic variants were evaluated for a phenotype–genotype correlation. MYO7A variants were detected in 4.7% of post-lingual families, and 12 of 14 families were multiplex. Five potentially pathogenic missense variants were identified. Fourteen variants causing autosomal dominant deafness were clustered in motor and MyTH4 domains of MYO7A protein. Missense variants in the motor domain caused late onset of hearing loss with ascending tendency. A severe audiological phenotype was apparent in individuals carrying tail domain variants. We report two new pathogenic variants responsible for DFNA11 in the Korean ADHL population. Dominant pathogenic variants of MYO7A occur frequently in motor and MyTH4 domains. Audiological differences among individuals correspond to specific domains which contain the variants. Therefore, appropriate rehabilitation is needed, particularly for patients with late-onset familial hearing loss. Full article

Sensorineural hearing loss (SNHL) is one of the most common sensory deficits worldwide, and genetic factors contribute to at least 50–60% of the congenital hearing loss cases. The transmembrane channel-like protein 1 (TMC1) gene has been linked to autosomal recessive (DFNB7/11) and autosomal dominant (DFNA36) non-syndromic hearing loss, and it is a relatively common genetic cause of SNHL. Here, we report eight Finnish families with 11 affected family members with either recessively inherited homozygous or compound heterozygous TMC1 variants associated with congenital moderate-to-profound hearing loss, or a dominantly inherited heterozygous TMC1 variant associated with postlingual progressive hearing loss. We show that the TMC1 c.1534C>T, p.(Arg512*) variant is likely a founder variant that is enriched in the Finnish population. We describe a novel recessive disease-causing TMC1 c.968A>G, p.(Tyr323Cys) variant. We also show that individuals in this cohort who were diagnosed early and received timely hearing rehabilitation with hearing aids and cochlear implants (CI) have reached good speech perception in noise. Comparison of the genetic data with the outcome of CI rehabilitation increases our understanding of the extent to which underlying pathogenic gene variants explain the differences in CI rehabilitation outcomes. Full article