Genetic diagnosis of childhood sensorineural hearing loss.

INTRODUCTION: Congenital/early-onset sensorineural hearing loss (SNHL) is one of the most common hereditary disorders in our environment. There is increasing awareness of the importance of an etiologic diagnosis, and genetic testing with next-generation sequencing (NGS) has the highest diagnostic yield. Our study shows the genetic results obtained in a cohort of patients with bilateral congenital/early-onset SNHL. MATERIALS AND METHODS: We included 105 children with bilateral SNHL that received genetic testing between 2019 and 2022. Genetic tests were performed with whole exome sequencing, analyzing genes related to hearing loss (virtual panel with 244 genes). RESULTS: 48% (50/105) of patients were genetically diagnosed. We identified pathogenic and likely pathogenic variants in 26 different genes, and the most frequently mutated genes were GJB2, USH2A and STRC. 52% (26/50) of variants identified produced non-syndromic hearing loss, 40% (20/50) produced syndromic hearing loss, and the resting 8% (4/50) could produce both non-syndromic and syndromic hearing loss. CONCLUSIONS: Genetic testing plays a vital role in the etiologic diagnosis of bilateral SNHL. Our cohort shows that genetic testing with NGS has a high diagnostic yield and can provide useful information for the clinical workup of patients.

Phenotypic characterization of retinitis pigmentosa associated with deafness / Caracterización fenotípica de la retinitis pigmentaria asociada a sordera

Introduction: There are several syndromes that associate retinitis pigmentosa with deafness or hearing loss. The most frequent is Usher syndrome, a genetic disorder of autosomal recessive inheritance, which, in some cases, is accompanied by vestibular dysfunction. However, there are cases of families that despite having retinitis pigmentosa associated with deafness, cannot be classified as Usher or other syndromes due to additional findings. Objective: To reassess the phenotypes of 103 families previously diagnosed as possible Usher syndrome and/or retinitis pigmentosa associated with deafness. Materials and methods: We conducted a descriptive and retrospective study by reviewing the medical records of 103 families with a probable clinical diagnosis of Usher syndrome and/or retinitis pigmentosa associated with deafness. Families whose clinical diagnosis did not correspond to the typical Usher syndrome were selected and evaluated ophthalmologically and audiologically. Demographic and clinical variables were analyzed. Results: We selected and then reevaluated 14 families and 55 individuals as they did not correspond to a clinical diagnosis of Usher syndrome; 13.6% of the families initially considered to have typical Usher syndrome were later diagnosed with retinitis pigmentosa associated with deafness, another ocular symptom associated with hearing loss, retinitis pigmentosa, or isolated hearing loss in the same family. Conclusions: Family studies are essential in cases where the symptoms do not match the typical Usher' syndrome. In the cases of retinitis pigmentosa associated with deafness, a correct clinical diagnosis allows for focusing on the molecular analyses to establish a differential diagnosis. The need for nomenclature guidelines on these atypical findings is relevant to aid physicians and researchers in the best approach to these cases.

Introducción. El síndrome de Usher es una alteración genética caracterizada por la asociación de retinitis pigmentaria y sordera. Sin embargo, hay casos con familias en las cuales, a pesar de presentarse dicha asociación, no se puede diagnosticar un síndrome de Usher ni ninguno otro. Objetivo. Reevaluar fenotípicamente a 103 familias con diagnóstico previo de posible síndrome de Usher o retinitis pigmentaria asociada con sordera. Materiales y métodos. Se revisaron las historias clínicas de 103 familias con un posible diagnóstico clínico de síndrome de Usher o retinitis pigmentaria asociada con sordera. Se seleccionaron las familias cuyo diagnóstico clínico no correspondía a un síndrome de Usher típico. Los afectados fueron valorados oftalmológica y audiológicamente. Se analizaron variables demográficas y clínicas. Resultados. Se reevaluaron 14 familias cuyo diagnóstico clínico no correspondía al de síndrome de Usher. De las familias con diagnóstico inicial de síndrome de Usher típico, el 13,6 % recibieron uno posterior de "retinitis pigmentaria asociada con sordera", de "otro síntoma ocular asociado con hipoacusia", o en forma aislada en una misma familia, de "retinitis pigmentaria" o "hipoacusia". Conclusiones. Es fundamental el estudio familiar en los casos en que la clínica no concuerda con el diagnóstico de síndrome de Usher típico. En los pacientes con retinitis pigmentaria asociada con sordera, el diagnóstico clínico acertado permite enfocar los análisis moleculares y, así, establecer un diagnóstico diferencial. Es necesario elaborar guías de nomenclatura en los casos con estos hallazgos atípicos para orientar a médicos e investigadores en cuanto a su correcto manejo.

Usher syndrome type 2A complicated with glycogen storage disease type 3 due to paternal uniparental isodisomy of chromosome 1 in a sporadic patient.

BACKGROUND: The condition of uniparental disomy (UPD) occurs when an individual inherits two copies of a chromosome, or part of a chromosome, from one parent. Most cases of uniparental heterodisomy (UPhD) do not cause diseases, whereas cases of uniparental isodisomy (UPiD), while rare, may be pathogenic. Theoretically, UPiD may cause rare genetic diseases in a homozygous recessive manner. METHODS: A 4-year-old girl presented with congenital hearing loss, developmental delay, hepatomegaly, and other clinical features. She and her parents were genetically tested using trio whole exome sequencing (Trio-WES) and copy number variation sequencing (CNV-seq). In addition, we built a structural model to further examine the pathogenicity of the UPiD variants. RESULTS: Trio-WES identified a paternal UPiD in chromosome 1, and two homozygous pathogenic variants AGL c.4284T>G/p.Tyr1428* and USH2A c.6528T>A/p.Tyr2176* in the UPiD region. We further analyzed the pathogenicity of these two variations. The patient was diagnosed with Usher syndrome type 2A (USH2A) and glycogen storage disease type III (GSD3). CONCLUSIONS: Our study reports a rare case of a patient carrying two pathogenic variants of different genes caused by paternal UPiD, supporting the potential application of Trio-WES in detecting and facilitating the diagnosis of UPD.

L-type voltage-gated calcium channel agonists mitigate hearing loss and modify ribbon synapse morphology in the zebrafish model of Usher syndrome type 1.

The mariner (myo7aa-/- ) mutant is a zebrafish model for Usher syndrome type 1 (USH1). To further characterize hair cell synaptic elements in myo7aa-/- mutants, we focused on the ribbon synapse and evaluated ultrastructure, number and distribution of immunolabeled ribbons, and postsynaptic densities. By transmission electron microscopy, we determined that myo7aa-/- zebrafish have fewer glutamatergic vesicles tethered to ribbon synapses, yet maintain a comparable ribbon area. In myo7aa-/- hair cells, immunolocalization of Ctbp2 showed fewer ribbon-containing cells in total and an altered distribution of Ctbp2 puncta compared to wild-type hair cells. myo7aa-/- mutants have fewer postsynaptic densities - as assessed by MAGUK immunolabeling - compared to wild-type zebrafish. We quantified the circular swimming behavior of myo7aa-/- mutant fish and measured a greater turning angle (absolute smooth orientation). It has previously been shown that L-type voltage-gated calcium channels are necessary for ribbon localization and occurrence of postsynaptic density; thus, we hypothesized and observed that L-type voltage-gated calcium channel agonists change behavioral and synaptic phenotypes in myo7aa-/- mutants in a drug-specific manner. Our results indicate that treatment with L-type voltage-gated calcium channel agonists alter hair cell synaptic elements and improve behavioral phenotypes of myo7aa-/- mutants. Our data support that L-type voltage-gated calcium channel agonists induce morphological changes at the ribbon synapse - in both the number of tethered vesicles and regarding the distribution of Ctbp2 puncta - shift swimming behavior and improve acoustic startle response.

Hickam's Dictum: Pseudoxanthoma elasticum and Usher syndrome in a single patient.

BACKGROUND: To report the case of a patient with two distinct genetic systemic diseases - pseudoxanthoma elasticum (PXE) and Usher syndrome - confirmed by genetic testing. MATERIALS AND METHODS: Single Retrospective Case Report. RESULTS: A 36-year-old woman presented with acute central vision loss of the left eye (OS). Fundus exam revealed choroidal neovascularization OS in the setting of angioid streaks secondary to an underlying diagnosis of PXE. Unexpectedly, she also exhibited peripheral bony spicules with significant visual field constriction. Physical exam revealed skin papules on her neck and hearing loss. The presence of angioid streaks and skin findings was compatible with PXE; the etiology of her pigmentary retinopathy and hearing loss was elucidated using genetic testing. The patient was found to be compound heterozygous for pathogenic variants in both the ABCC6 and USH2A genes, confirming the diagnosis of two rare disorders in a single patient. CONCLUSIONS: PXE and Usher syndrome are rare systemic disorders that cause distinctive retinal abnormalities. This report highlights the importance of genetic testing in diagnosing uncommon hereditary retinal disorders and outlines the progression of disease over 6 years.

Life strategies of people with deafblindness due to Usher syndrome type 2a - a qualitative study.

Purpose: To explore life strategies in people with Usher syndrome type 2a. Background: There are no studies on life strategies in people with Usher syndrome. People with deafblindness are often described in terms of poor health and low quality of life, or as being vulnerable. From a clinical point of view, it is of importance to balance this picture, with an increased knowledge of life strategies. Methods: The study had a qualitative explorative design. Fourteen people aged 20-64 years (4 women, 10 men) with USH2a in Sweden participated in focus group interviews, which were transcribed and analysed by qualitative content analysis. Results: The content analysis resulted in seven categories; remaining active, using devices, using support, sharing knowledge, appreciating the present, maintaining a positive image and alleviating emotional pain. Two sub-themes: resolve or prevent challenges and comforting oneself was abstracted forming a theme "being at the helm". Conclusion: The findings show that people with USH2a have a variety of life strategies that can be interpreted as highlighting different aspects of psychological flexibility in a life adjustment process. The study demonstrates that people with USH2a manage in many ways, and metaphorically, by "taking the helm", they strive to actively navigate towards their own chosen values.

Evidence for impaired olfactory function and structural brain integrity in a disorder of ciliary function, Usher syndrome.

Diseases involving cilia dysfunction, such as Usher Syndrome (USH), often involve visual and auditory loss. Psychophysical evidence has suggested that this may also hold true for the peripheral olfactory domain. Here we aimed to go a step further by attempting to establish relations between the integrity of cortical structures and olfactory function in this condition. We investigated olfactory function for USH types 1 (USH1) and 2 (USH2). Bilateral olfactory bulb (OB) volume and olfactory sulcus (OS) depth were also analysed. Thirty-three controls with no previous olfactory deficits were age, sex and handedness-matched to 32 USH patients (11 USH1, 21 USH2). A butanol detection threshold test was performed to measure olfactory function. For OB volume and OS depth, morphometric measurements were performed using magnetic resonance imaging (MRI) based on detailed segmentation by three independent operators. Averaged values across these were used for the statistical analyses. Total intracranial volume was estimated using Freesurfer to account for head size variability. Olfactory threshold was significantly lower in controls when compared to USH, USH1, and USH2. OS depth was found to be shallower in both hemispheres in USH patients when compared with the control group. OB volume was not significantly different between control and USH groups, or respective subgroups. Nevertheless, butanol threshold was negatively correlated with the left OB volume for the USH type 1 subgroup. The main effect of OS depth reduction was found to be mainly due to the comparison between USH2 and controls. Our results provide evidence for morphometric changes and olfactory dysfunction in patients with USH. This correlated with a reduction in left OB volume in the USH1 subgroup, the most severe USH phenotype. The main effect of reduced OS depth was found to stem mainly from USH2 raising questions regarding a possible complex interaction between sensory olfactory loss and central cortical changes in this disease.

The first deaf-blind patient in Russia with Argus II retinal prosthesis system: what he sees and why.

OBJECTIVE: In this study, we propose a new method for evaluating the functional results based on the sizes of phosphenes that the patient drew which were then digitalized. We also describe the methodology of psychological testing and support for a deaf-blind patient. APPROACH: A 59-year-old man with retinitis pigmentosa and hearing loss (clinical Usher syndrome) underwent surgery to implant the Argus II retinal prosthesis system in his right eye. MAIN RESULTS: Correlation analysis showed a weak dependency between the size of a phosphene and the perceptual threshold. Significant correlations between a phosphene and the height of the interface, impedance or retinal thickness was not found. The patient with the retinal prosthesis felt more independent and confident, and more healthy. This is the first case of retinal implant surgery in Russia. SIGNIFICANCE: The results of this study add to the understanding in the field of retinal implants functioning. The experience of the successful rehabilitation of the deaf-blind patient after implantation of Argus II allowed us to design a methodology that can be used in future similar cases.

Hearing-impaired young people - a physician's guide .

Physicians reading this will have a broad range of in-depth knowledge about their own subspecialty. However, in daily medical practice there are topics of which all physicians should have some knowledge. Those who deal with young people should have some knowledge of the needs of the hearing-impaired population within this group of patients. This article is intended to provide an overview of young people with hearing impairment (HIYP), the challenges they face and what we can do to help them. In this paper, we assume that data published regarding hearing-impaired children apply to HIYP from 13 years (the age at which the transition process begins) to 25 years of age (the age at which 'youth' according to the World health Organization and the Education Health Care Plan ends).

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.

Modeling and Preventing Progressive Hearing Loss in Usher Syndrome III.

Usher syndrome type III (USH3) characterized by progressive loss of vision and hearing is caused by mutations in the clarin-1 gene (CLRN1). Clrn1 knockout (KO) mice develop hair cell defects by postnatal day 2 (P2) and are deaf by P21-P25. Early onset profound hearing loss in KO mice and lack of information about the cochlear cell type that requires Clrn1 expression pose challenges to therapeutic investigation. We generated KO mice harboring a transgene, TgAC1, consisting of Clrn1-UTR (Clrn1 cDNA including its 5' and 3' UTR) under the control of regulatory elements (Atoh1 3' enhancer/ß-globin basal promoter) to direct expression of Clrn1 in hair cells during development and down regulate it postnatally. The KO-TgAC1 mice displayed delayed onset progressive hearing loss associated with deterioration of the hair bundle structure, leading to the hypothesis that hair cell expression of Clrn1 is essential for postnatal preservation of hair cell structure and hearing. Consistent with that hypothesis, perinatal transfection of hair cells in KO-TgAC1 mice with a single injection of AAV-Clrn1-UTR vector showed correlative preservation of the hair bundle structure and hearing through adult life. Further, the efficacy of AAV-Clrn1 vector was significantly attenuated, revealing the potential importance of UTR in gene therapy.

Characterization of the ternary Usher syndrome SANS/ush2a/whirlin protein complex.

The Usher syndrome (USH) is the most common form of inherited deaf-blindness, accompanied by vestibular dysfunction. Due to the heterogeneous manifestation of the clinical symptoms, three USH types (USH1-3) and additional atypical forms are distinguished. USH1 and USH2 proteins have been shown to function together in multiprotein networks in photoreceptor cells and hair cells. Mutations in USH proteins are considered to disrupt distinct USH protein networks and finally lead to the development of USH.To get novel insights into the molecular pathomechanisms underlying USH, we further characterize the periciliary USH protein network in photoreceptor cells. We show the direct interaction between the scaffold protein SANS (USH1G) and the transmembrane adhesion protein ush2a and that both assemble into a ternary USH1/USH2 complex together with the PDZ-domain protein whirlin (USH2D) via mutual interactions. Immunohistochemistry and proximity ligation assays demonstrate co-localization of complex partners and complex formation, respectively, in the periciliary region, the inner segment and at the synapses of rodent and human photoreceptor cells. Protein-protein interaction assays and co-expression of complex partners reveal that pathogenic mutations in USH1G severely affect formation of the SANS/ush2a/whirlin complex. Translational read-through drug treatment, targeting the c.728C > A (p.S243X) nonsense mutation, restored SANS scaffold function. We conclude that USH1 and USH2 proteins function together in higher order protein complexes. The maintenance of USH1/USH2 protein complexes depends on multiple USH1/USH2 protein interactions, which are disrupted by pathogenic mutations in USH1G protein SANS.

Usher syndrome Type I in an adult Nepalese male: a rare case report.

Usher syndrome, also known as retinitis pigmentosa-dysacusis syndrome, is an extremely rare genetic disorder, characterized by retinitis pigmentosa (RP) and congenital sensorineural hearing loss. It has been estimated to account for 3-6% of the congenitally deaf population, upto 8-33% of individuals with RP and half of all cases with combined deafness and blindness (Vernon M,1969; Boughman JA et al,1983). The prevalence of Usher syndrome have been reported to range from 3.5 to 6.2 per 100,000 in different populations (Vernon M,1969; Boughman JA et al,1983; Yan D et al, 2010). We report a case of Usher syndrome type I in an adult Nepalese male with typical congenital profound hearing loss, and night blindness secondary to retinitis pigmentosa.

The combination of vestibular impairment and congenital sensorineural hearing loss predisposes patients to ocular anomalies, including Usher syndrome.

The co-occurrence of hearing impairment and visual dysfunction is devastating. Most deaf-blind etiologies are genetically determined, the commonest being Usher syndrome (USH). While studies of the congenitally deaf population reveal a variable degree of visual problems, there are no effective ophthalmic screening guidelines. We hypothesized that children with congenital sensorineural hearing loss (SNHL) and vestibular impairment were at an increased risk of having USH. A retrospective chart review of 33 cochlear implants recipients for severe to profound SNHL and measured vestibular dysfunction was performed to determine the ocular phenotype. All the cases had undergone ocular examination and electroretinogram (ERG). Patients with an abnormal ERG underwent genetic testing for USH. We found an underlying ocular abnormality in 81.81% (27/33) of cases; of which 75% had refractive errors, and 50% of those patients showed visual improvement with refractive correction. A total of 14 cases (42.42%; 14/33) had generalized rod-cone dysfunction on ERG suggestive of Usher syndrome type 1, confirmed by mutational analysis. This work shows that adding vestibular impairment as a criterion for requesting an eye exam and adding the ERG to detect USH increases the chances of detecting ocular anomalies, when compared with previous literature focusing only on congenital SNHL.

Impairment of Vision in a Mouse Model of Usher Syndrome Type III.

PURPOSE: The purpose of this study was to obtain an Usher syndrome type III mouse model with retinal phenotype. METHODS: Speed congenic method was used to obtain Clrn1 exon 1 knockout (Clrn1-/-) and Clrn1N48K knockin (Clrn1N48K/N48K) mice under A/J background. To study the retinal functions of these mice, we measured scotopic and photopic ERG responses. To observe if there are any structural abnormalities, we conducted light and transmission electron microscopy of fixed retinal specimens. RESULTS: In 3-month-old Clrn1-/- mice, scotopic b-wave amplitude was reduced by more than 25% at the light intensities from -2.2 to 0.38 log cd·s/m2, but scotopic a-wave amplitudes were comparable to those of age-matched wild type mice at all the light intensities tested. In 9-month-old Clrn1-/- mice, scotopic b-wave amplitudes were further reduced by more than 35%, and scotopic a-wave amplitude also showed a small decline as compared with wild type mice. Photopic ERG responses were comparable between Clrn1-/- and wild type mice. Those electrophysiological defects were not associated with a loss of rods. In Clrn1N48K/N48K mice, both a- and b-wave amplitudes were not discernable from those of wild type mice aged up to 10 months. CONCLUSIONS: Mutations that are Clrn1-/- biallelic cause visual defects when placed under A/J background. The absence of apparent rod degeneration suggests that the observed phenotype is due to functional defects, and not due to loss of rods. Biallelic Clrn1N48K/N48K mutations did not cause discernible visual defects, suggesting that Clrn1- allele is more severely dysfunctional than ClrnN48K allele.

Novel grading system for quantification of cystic macular lesions in Usher syndrome.

BACKGROUND: To evaluate novel grading system used to quantify optical coherence tomography (OCT) scans for cystic macular lesions (CML) in Usher syndrome (USH) patients, focusing on CML associated alterations in MOY7A and USH2A mutations. METHODS: Two readers evaluated 76 patients' (mean age 42 ± 14 years) data prospectively uploaded on Eurush database. OCT was used to obtain high quality cross-sectional images through the fovea. The CML was graded as none, mild, moderate or severe, depending on the following features set: subretinal fluid without clearly detectable CML boundaries; central macular thickness; largest diameter of CML; calculated mean of all detectable CML; total number of detectable CML; retinal layers affected by CML. Intra-and inter-grader reproducibility was evaluated. RESULTS: CML were observed in 37 % of USH eyes, while 45 % were observed in MYO7A and 29 % in USH2A cases. Of those with CML: 52 % had mild, 22 % had moderate and 26 % had severe changes, respectively. CML were found in following retinal layers: 50 % inner nuclear layer, 44 % outer nuclear layer, 6 % retinal ganglion cell layer. For the inter-grader repeatability analysis, agreements rates for CML were 97 % and kappa statistics was 0.91 (95 % CI 0.83-0.99). For the intra-grader analysis, agreement rates for CML were 98 %, while kappa statistics was 0.96 (95 % CI 0.92-0.99). CONCLUSIONS: The novel grading system is a reproducible tool for grading OCT images in USH complicated by CML, and potentially could be used for objective tracking of macular pathology in clinical therapy trials.