The prevalence and clinical features of MYO7A-related hearing loss including DFNA11, DFNB2 and USH1B.

The MYO7A gene is known to be responsible for both syndromic hearing loss (Usher syndrome type1B:USH1B) and non-syndromic hearing loss including autosomal dominant and autosomal recessive inheritance (DFNA11, DFNB2). However, the prevalence and detailed clinical features of MYO7A-associated hearing loss across a large population remain unclear. In this study, we conducted next-generation sequencing analysis for a large cohort of 10,042 Japanese hearing loss patients. As a result, 137 patients were identified with MYO7A-associated hearing loss so that the prevalence among Japanese hearing loss patients was 1.36%. We identified 70 disease-causing candidate variants in this study, with 36 of them being novel variants. All variants identified in autosomal dominant cases were missense or in-frame deletion variants. Among the autosomal recessive cases, all patients had at least one missense variant. On the other hand, in patients with Usher syndrome, almost half of the patients carried biallelic null variants (nonsense, splicing, and frameshift variants). Most of the autosomal dominant cases showed late-onset progressive hearing loss. On the other hand, cases with autosomal recessive inheritance or Usher syndrome showed congenital or early-onset hearing loss. The visual symptoms in the Usher syndrome cases developed between age 5-15, and the condition was diagnosed at about 6-15 years of age.

Syndromic Retinitis Pigmentosa: A 15-Patient Study.

Retinitis pigmentosa is a group of genetically determined retinal dystrophies characterized by primary photoreceptor apoptosis and can occur in isolated or syndromic conditions. This study reviewed the clinical data of 15 patients with syndromic retinitis pigmentosa from a Rare Disease Reference Center in Brazil and the results of their next-generation sequencing tests. Five males and ten females participated, with the mean ages for ocular disease onset, fundoscopic diagnosis, and molecular evaluation being 9, 19, and 29 years, respectively. Bardet-Biedl syndrome (n = 5) and Usher syndrome (n = 3) were the most frequent diagnoses, followed by other rare conditions. Among the patients, fourteen completed molecular studies, with three negative results and eleven revealing findings in known genes, including novel variants in MKKS (c.432_435del, p.Phe144Leufs*14), USH2A (c.(7301+1_7302-1)_(9369+1_9370-1)del), and CEP250 (c.5383dup, p.Glu1795Glyfs*13, and c.5050del, p.Asp1684Thrfs*9). Except for Kearn-Sayre, all presented an autosomal recessive inheritance pattern with 64% homozygosity results. The long gap between symptom onset and diagnosis highlights the diagnostic challenges faced by the patients. This study reaffirms the clinical heterogeneity of syndromic retinitis pigmentosa and underscores the pivotal role of molecular analysis in advancing our understanding of these diseases.

Exploring the support needs of Australian parents of young children with Usher syndrome: a qualitative thematic analysis.

BACKGROUND: Advancements in genetic testing have led to Usher syndrome now being diagnosed at a much earlier age than in the past, enabling the provision of early intervention and support to children and families. Despite these developments, anecdotal reports suggest there are substantial gaps in the services and supports provided to parents of children with Usher syndrome. The current study investigated the support needs of parents of children with Usher syndrome Type 1 when their child was aged 0 to 5 years. METHOD: Purposive sampling was used, and six semi-structured interviews were conducted with Australian parents of children with Usher syndrome, Type 1. Data was analysed using modified reflexive thematic analysis. RESULTS: Four key themes were identified as being central to the support needs of parents of children with Usher syndrome aged 0 to 5 years. (1) Social Needs referred to parents' need for various sources of social support, (2) Informational Needs described the lack of information parents received regarding Usher syndrome from treating professionals, (3) Practical Needs included supports needed to assist parents in managing the day-to-day tasks of caring for a child with a disability, and (4) Emotional Needs represented the emotional support (both formal and informal) that parents needed to be a positive support to their child. CONCLUSIONS: Findings provide rich information for relevant support groups, policy makers, individual healthcare professionals, and professional governing bodies regarding the education of stakeholders and the development and implementation of best-practice treatment guidelines.

Vestibulo-ocular reflex dynamics with head-impulses discriminates Usher patients type 1 and 2.

Usher Syndrome classification takes into account the absence of vestibular function but its correlation with genotype is not well characterized. We intend to investigate whether video Head Impulse Test (vHIT) is useful in screening and to differentiate Usher Syndrome types. 29 Usher patients (USH) with a genetically confirmed diagnosis and 30 healthy controls were studied with vHIT and dizziness handicap inventory questionnaire (DHI). Statistical significant differences between USH1, USH2 and controls were found in the vestibulo-ocular-reflex (VOR) gain of all SCCs, with USH1 patients consistently presenting smaller gains. VOR gain of the right lateral SCC could discriminate controls from USH1, and USH2 from USH1 with an overall diagnostic accuracy of 90%. USH1 DHI correlated with VOR (ρ = - 0,971, p = 0.001). Occurrence rate of covert and overt lateral semicircular canals refixation saccades (RS) was significantly different between groups, being higher in USH1 patients (p < 0.001). USH1 peak velocity of covert and overt saccades was higher for lateral semicircular canals (p < 0.05 and p = 0.001) compared with USH2 and controls. Covert saccades occurrence rate for horizontal SCCs could discriminate USH1 from USH2 patients and controls with a diagnostic accuracy of 85%. vHIT is a fast and non-invasive instrument which allowed us to screen and distinguish Usher patients from controls with a high precision. Importantly, its use allowed further discrimination between USH1 from USH2 groups. Moreover, VOR gain seems to correlate with vertigo-related quality of life in more severe phenotypes.

Extended time frame for restoring inner ear function through gene therapy in Usher1G preclinical model.

Neonatal gene therapy has been shown to prevent inner ear dysfunction in mouse models of Usher syndrome type I (USH1), the most common genetic cause of combined deafness-blindness and vestibular dysfunction. However, hearing onset occurs after birth in mice and in utero in humans, making it questionable how to transpose murine gene therapy outcomes to clinical settings. Here, we sought to extend the therapeutic time window in a mouse model for USH1G to periods corresponding to human neonatal stages, more suitable for intervention in patients. Mice with deletion of Ush1g (Ush1g-/-) were subjected to gene therapy after the hearing onset. The rescue of inner ear hair cell structure was evaluated by confocal imaging and electron microscopy. Hearing and vestibular function were assessed by recordings of the auditory brain stem response and vestibulo-ocular reflex and by locomotor tests. Up to P21, gene therapy significantly restored both the hearing and balance deficits in Ush1g-/- mice. However, beyond this age and up to P30, vestibular function was restored but not hearing. Our data show that effective gene therapy is possible in Ush1g-/- mice well beyond neonatal stages, implying that the therapeutic window for USH1G may be wide enough to be transposable to newborn humans.

Multidisciplinary approach to inherited causes of dual sensory impairment.

PURPOSE: This article presents a review of the main causes of inherited dual sensory impairment (DSI) with an emphasis on the multidisciplinary approach. METHODS: A narrative review of English literature published before January 2023 was conducted using PubMed, Medline, and Scopus databases. The different causes of inherited DSI are discussed from a multidisciplinary perspective. RESULTS: There are a wide range of dual sensory impairment (DSI), commonly referred to as blindness and deafness. While Usher syndrome is the most frequent genetic cause, other genetic syndromes such as Alport syndrome or Stickler syndrome can also lead to DSI. Various retinal phenotypes, including pigmentary retinopathy as seen in Usher syndrome, vitreoretinopathy as in Stickler syndrome, and macular dystrophy as in Alport syndrome, along with type of hearing loss (sensorineural or conductive) and additional systemic symptoms can aid in diagnostic suspicion. A thorough ophthalmologic and otorhinolaryngologic examination can help guide diagnosis, which can then be confirmed with genetic studies, crucial for determining prognosis. Effective hearing rehabilitation measures, such as hearing implants, and visual rehabilitation measures, such as low vision optical devices, are crucial for maintaining social interaction and proper development in these patients. CONCLUSIONS: While Usher syndrome is the primary cause of inherited dual sensory impairment (DSI), other genetic syndromes can also lead to this condition. A proper diagnostic approach based on retinal phenotypes and types of hearing loss can aid in ruling out alternative causes. Multidisciplinary approaches can assist in reaching a definitive diagnosis, which has significant prognostic implications.

The p.C759F Variant in USH2A Is a Pathogenic Mutation: Systematic Literature Review and Meta-Analysis of 667 Genotypes.

BACKGROUND: Although the p.C759F (c.2276G>T, p.Cys759Phe) variant in the USH2A gene has been identified in association with retinal degeneration by several authors, its pathogenicity has been questioned once by the publication of two unaffected homozygotes from a single family. OBJECTIVES: The objective of the study was to ascertain the role of p.C759F in hereditary retinal disease. METHODS: We examined 87 research articles reporting on patients carrying this variant and then used this information as primary data for a series of meta-analytical tests. RESULTS: Independent statistical analyses showed that p.C759F (i) is highly enriched in patients with respect to healthy individuals, (ii) represents a clear-cut recessive allele causing disease when it is in trans with other mutations, (iii) is pathogenic in homozygotes. CONCLUSIONS: Our results confirm that p.C759F is a bona fide mutation, leading to retinal blindness according to a recessive pattern of inheritance.

Functional Vision in Patients With Biallelic USH2A Variants.

PURPOSE: To describe functional vision (FV) and investigate the relationship between FV, visual acuity (VA), and hill of vision (VTOT) at baseline in patients with biallelic USH2A variants. DESIGN: Multicenter, international, cross-sectional study. METHODS: In individuals with biallelic disease-causing variants in USH2A, clinical diagnosis of Usher syndrome type 2 (USH2) or autosomal recessive nonsyndromic retinitis pigmentosa (ARRP) was based on history of hearing loss and audiology examinations. The VALVVFQ-48 was administered verbally to participants ≥18 years old. VA was measured in both eyes; VTOT was determined from static perimetry in the study eye (better VA). FV scores were calculated using Rasch analysis. RESULTS: Median age of 121 participants (76 with USH2, 45 with ARRP) was 41 years (range: 19-80); 54% were female. FV scores varied from -2.0 to 7.6 logits (median [interquartile range (IQR)]: 2.8 [1.5-3.8]). ARRP and USH2 participants had similar FV scores, both before [mean (95% CI): 2.8 (2.3-3.4) and 2.7 (2.3-3.2), respectively], and after [mean (95% CI): 2.5 (2.1-3.0) and 2.9 (2.6-3.3), respectively; P = .24] adjusting for age, VA, disease duration, and VTOT. VA and VTOT accounted for 29% and 26% of the variance in FV scores, respectively (P < .001 for each). Together, they accounted for 36% of variance observed. CONCLUSIONS: Biallelic USH2A variants were associated with a large range of FV, yet similar in ARRP and USH2, despite hearing loss in USH2. The modified VALVVFQ-48 we evaluated is not ideal for detecting the impact of USH2A-associated retinal degenerations on activities of daily living.

Late-onset mucopolysaccharidosis type IIIA mimicking Usher syndrome.

Mucopolysaccharidosis type IIIA (MPS IIIA or Sanfilippo syndrome type A) is an autosomal recessive lysosomal storage disorder caused by pathogenic variants in the SGSH gene encoding N-sulfoglucosamine sulfohydrolase, an enzyme involved in the degradation of heparan sulfate. MPS IIIA is typically characterized by neurocognitive decline and hepatosplenomegaly with childhood onset. Here, we report on a 53-year-old male subject initially diagnosed with Usher syndrome for the concurrence of retinitis pigmentosa and sensorineural hearing loss. Clinical exome sequencing identified biallelic missense variants in SGSH, and biochemical assays showed complete deficiency of sulfamidase activity and increased urinary glycosaminoglycan excretion. Reverse phenotyping revealed left ventricle pseudo-hypertrophy, hepatosplenomegaly, bilateral deep white matter hyperintensities upon brain MRI, and decreased cortical metabolic activity by PET-CT. On neuropsychological testing, the proband presented only partial and isolated verbal memory deficits. This case illustrates the power of unbiased, comprehensive genetic testing for the diagnosis of challenging mild or atypical forms of MPS IIIA.

Multimodal photoacoustic microscopy, optical coherence tomography, and fluorescence imaging of USH2A knockout rabbits.

Usher syndrome type 2A (USH2A) is a genetic disorder characterized by retinal degeneration and hearing loss. To better understand the pathogenesis and progression of this syndrome, animal models such as USH2A knockout (USH2AKO) rabbits have been developed. In this study, we employed multimodal imaging techniques, including photoacoustic microscopy (PAM), optical coherence tomography (OCT), fundus autofluorescence (FAF), fluorescein angiography (FA), and indocyanine green angiography (ICGA) imaging to evaluate the retinal changes in the USH2AKO rabbit model. Twelve New Zealand White rabbits including USH2AKO and wild type (WT) were used for the experiments. Multimodal imaging was implemented at different time points over a period of 12 months to visualize the progression of retinal changes in USH2AKO rabbits. The results demonstrate that ellipsoid zone (EZ) disruption and degeneration, key features of Usher syndrome, began at the age of 4 months old and persisted up to 12 months. The EZ degeneration areas were clearly observed on the FAF and OCT images. The FAF images revealed retinal pigment epithelium (RPE) degeneration, confirming the presence of the disease phenotype in the USH2AKO rabbits. In addition, PAM images provided high-resolution and high image contrast of the optic nerve and the retinal microvasculature, including retinal vessels, choroidal vessels, and capillaries in three-dimensions. The quantification of EZ fluorescent intensity using FAF and EZ thickness using OCT provided comprehensive quantitative data on the progression of degenerative changes over time. This multimodal imaging approach allowed for a comprehensive and non-invasive assessment of retinal structure, microvasculature, and degenerative changes in the USH2AKO rabbit model. The combination of PAM, OCT, and fluorescent imaging facilitated longitudinal monitoring of disease progression and provided valuable insights into the pathophysiology of USH2A syndrome. These findings contribute to the understanding of USH2A syndrome and may have implications for the development of diagnostic and therapeutic strategies for affected individuals. The multimodal imaging techniques employed in this study offer a promising platform for preclinical evaluation of potential treatments and may pave the way for future clinical applications in patients with Usher syndrome.

[Advances on gene therapy for USH2A exon 13 related inherited retinal dystrophy].

Biallelic pathogenic variants in the USH2A gene result in Usher syndrome type Ⅱ and non-syndromic retinitis pigmentosa, both of which entail the progressive loss of photoreceptors leading to blindness. The cDNA of the USH2A gene is extensive, consisting of 15 606 base pairs, rendering it impractical for delivery via adeno-associated virus vectors for gene replacement therapy. Notably, exon 13 has emerged as a focal point for therapeutic intervention, given its predilection for harboring the most pathogenic variants within USH2A. Recent intervention studies targeting USH2A exon 13 through the utilization of antisense oligonucleotides, genome editing, and RNA editing approaches have exhibited promising therapeutic potential. This paper provides a comprehensive overview of the molecular mechanisms, outcome data, and the challenges associated with the application of these interventions in this domain.

Identification of a novel compound heterozygous pathogenic variant in MYO7A causing Usher syndrome type IB in a Chinese patient: a case report.

Herein, we report the clinical and genetic features of a patient with Usher syndrome type IB to improve our collective understanding of the disorder. The patient was a teenaged boy with congenital profound hearing loss, progressive visual loss, and vestibular hypoplasia; his parents were phenotypically normal. His pure tone audiometry hearing thresholds were 100 dB at all frequencies, and distortion product otoacoustic emission was not elicited at any frequencies in either ear. Moreover, an auditory brainstem response test at 100 dB normal hearing level revealed no relevant response waves, and a caloric test showed vestibular hypoplasia. Fundus examination revealed retinitis pigmentosa and a reduced visual field. The use of high-throughput sequencing technology to screen the patient's family lineage for deafness-related genes revealed that the patient carried a compound heterozygous pathogenic variant of MYO7A: c.541C > T and c.6364delG. This pathogenic variant has not previously been reported. Our findings may provide a basis for genetic counseling, effective treatment, and/or gene therapy for Usher syndrome.

Allelic hierarchy for USH2A influences auditory and visual phenotypes in South Korean patients.

When medical genetic syndromes are influenced by allelic hierarchies, mutant alleles have distinct effects on clinical phenotypes. Genotype-phenotype correlations for Usher syndrome type 2 (USH2) suggest that the USH2A gene exhibits an allelic hierarchy. Here, we analyzed the phenotypes and genotypes of 16 South Korean patients with USH2A biallelic variants to investigate an allelic hierarchy from audiological and ophthalmological perspectives. Using whole exome and genome sequencing, 18 mutant alleles, including 4 novel alleles, were identified and implicated in USH2A-related disorders. Truncated alleles were linked to earlier onset of subjective hearing loss and more severe thresholds; biallelic truncated alleles had more severe effects. Truncated alleles were also associated with retinal structure degeneration and severe functional deterioration. However, younger patients (aged < 16 years) did not exhibit overt retinitis pigmentosa even when they had biallelic truncated alleles, suggesting that USH2A-related USH2 can mimic nonsyndromic hearing loss. For truncated alleles, there was a clear correlation between mean hearing threshold and 30-Hz flicker electroretinography implicit time. This study provides the first evidence of an USH2A-related allelic hierarchy among South Korean patients; our data yield valuable insights concerning the natural courses of clinical phenotypes and how genotype-based therapies may be used.

Third-generation lentiviral gene therapy rescues function in a mouse model of Usher 1B.

Usher syndrome 1B (USH1B) is a devastating genetic disorder with congenital deafness, loss of balance, and blindness caused by mutations in the myosin-VIIa (MYO7A) gene, for which there is currently no cure. We developed a gene therapy approach addressing the vestibulo-cochlear deficits of USH1B using a third-generation, high-capacity lentiviral vector system capable of delivering the large 6,645-bp MYO7A cDNA. Lentivirally delivered MYO7A and co-encoded dTomato were successfully expressed in the cochlear cell line HEI-OC1. In normal-hearing mice, both cochlea and the vestibular organ were efficiently transduced, and ectopic MYO7A overexpression did not show any adverse effects. In Shaker-1 mice, an USH1B disease model based on Myo7a mutation, cochlear and vestibular hair cells, the main inner ear cell types affected in USH1B, were successfully transduced. In homozygous mutant mice, delivery of MYO7A at postnatal day 16 resulted in a trend for partial recovery of auditory function and in strongly reduced balance deficits. Heterozygous mutant mice were found to develop severe hearing loss at 6 months of age without balance deficits, and lentiviral MYO7A gene therapy completely rescued hearing to wild-type hearing thresholds. In summary, this study demonstrates improved hearing and balance function through lentiviral gene therapy in the inner ear.

Novel pathogenic WHRN variant causing hearing loss in a moroccan family.

OBJECTIVES: The most prevalent sensory disease in humans is deafness. A variety of genes have been linked to hearing loss, which can either be isolated (non-syndromic) or associated with lesions in other organs (syndromic). It has been discovered that WHRN variants are responsible for non-syndromic hearing loss and Usher syndrome type II. METHODS AND RESULTS: Exome sequencing in a consanguineous Moroccan patient with severe hearing loss identified a single homozygous mutation c.619G > T; p.Ala207Ser in WHRN, encoding a cytoskeletal scaffold protein that binds membrane protein complexes to the cytoskeleton in ocular photoreceptors and ear hair cell stereocilia. Bioinformatics methods and molecular dynamic modeling were able to predict the pathogenic implications of this variation. CONCLUSION: We used whole exome sequencing to find a homozygous WHRN gene variant in a Moroccan family. Numerous bioinformatics methods predict that this modification might result in a change in the WHRN protein's structure.

Dual AAV-based PCDH15 gene therapy achieves sustained rescue of visual function in a mouse model of Usher syndrome 1F.

Mutations in the PCDH15 gene, encoding protocadherin-15, are among the leading causes of Usher syndrome type 1 (USH1F), and account for up to 12% USH1 cases worldwide. A founder truncating variant of PCDH15 has a ∼2% carrier frequency in Ashkenazi Jews accounting for nearly 60% of their USH1 cases. Although cochlear implants can restore hearing perception in USH1 patients, presently there are no effective treatments for the vision loss due to retinitis pigmentosa. We established a founder allele-specific Pcdh15 knockin mouse model as a platform to ascertain therapeutic strategies. Using a dual-vector approach to circumvent the size limitation of adeno-associated virus, we observed robust expression of exogenous PCDH15 in the retinae of Pcdh15KI mice, sustained recovery of electroretinogram amplitudes and key retinoid oxime, substantially improved light-dependent translocation of phototransduction proteins, and enhanced levels of retinal pigment epithelium-derived enzymes. Thus, our data raise hope and pave the way for future gene therapy trials in USH1F subjects.

Expression of two major isoforms of MYO7A in the retina: Considerations for gene therapy of Usher syndrome type 1B.

Usher syndrome type 1B (USH1B) is a deaf-blindness disorder, caused by mutations in the MYO7A gene, which encodes the heavy chain of an unconventional actin-based motor protein. Here, we examined the two retinal isoforms of MYO7A, IF1 and IF2. We compared 3D models of the two isoforms and noted that the 38-amino acid region that is present in IF1 but absent from IF2 affects the C lobe of the FERM1 domain and the opening of a cleft in this potentially important protein binding domain. Expression of each of the two isoforms of human MYO7A and pig and mouse Myo7a was detected in the RPE and neural retina. Quantification by qPCR showed that the expression of IF2 was typically âˆ¼ 7-fold greater than that of IF1. We discuss the implications of these findings for any USH1B gene therapy strategy. Given the current incomplete knowledge of the functions of each isoform, both isoforms should be considered for targeting both the RPE and the neural retina in gene augmentation therapies.

Optimization of Capillary-Based Western Blotting for MYO7A.

Myosin VIIA (MYO7A)-associated Usher syndrome type 1B (USH1B) is a severe disorder that impacts the auditory, vestibular, and visual systems of affected patients. Due to the large size (~7.5 kb) of the MYO7A coding sequence, we have designed a dual adeno-associated virus (AAV) vector-based approach for the treatment of USH1B-related vision loss. Due to the added complexity of dual-AAV gene therapy, careful attention must be paid to the protein products expressed following vector recombination. In order to improve the sensitivity and quantifiability of our immunoassays, we adapted our traditional western blot protocol for use with the Jess™ Simple Western System. Following several rounds of testing, we optimized our protocol for the detection of MYO7A in two of our most frequently used sample types, mouse eyes, and infected HEK293 cell lysates.

Detailed Clinical, Ophthalmic, and Genetic Characterization of ADGRV1-Associated Usher Syndrome.

PURPOSE: To present the clinical characteristics, retinal features, natural history, and genetics of ADGRV1-Usher syndrome (USH). DESIGN: Multicenter international retrospective cohort study. METHODS: Clinical notes, hearing loss history, multimodal retinal imaging, and molecular diagnosis were reviewed. Thirty patients (28 families) with USH type 2 and disease-causing variants in ADGRV1 were identified. Visual function, retinal imaging, and genetics were evaluated and correlated, with retinal features also compared with those of the commonest cause of USH type 2, USH2A-USH. RESULTS: The mean age at the first visit was 38.6 ± 12.0 years (range: 19-74 years), and the mean follow-up time was 9.0 ± 7.7 years. Hearing loss was reported in the first decade of life by all patients, 3 (10%) described progressive loss, and 93% had moderate-severe impairment. Visual symptom onset was at 17.0 ± 7.7 years of age (range: 6-32 years), with 13 patients noticing problems before the age of 16. At baseline, 90% of patients had no or mild visual impairment. The most frequent retinal features were a hyperautofluorescent ring at the posterior pole (70%), perimacular patches of decreased autofluorescence (59%), and mild-moderate peripheral bone-spicule-like deposits (63%). Twenty-six (53%) variants were previously unreported, 19 families (68%) had double-null genotypes, and 9 were not-double-null. Longitudinal analysis showed significant differences between baseline and follow-up central macular thickness (-1.25 µm/y), outer nuclear layer thickness (-1.19 µm/y), and ellipsoid zone width (-40.9 µm/y). The rate of visual acuity decline was 0.02 LogMAR (1 letter)/y, and the rate of constriction of the hyperautofluorescent ring was 0.23 mm2/y. CONCLUSIONS: ADGRV1-USH is characterized by early-onset, usually non-progressive, mild-to-severe hearing loss and generally good central vision until late adulthood. Perimacular atrophic patches and relatively retained ellipsoid zone and central macular thickness in later adulthood are more often seen in ADGRV1-USH than in USH2A-USH.