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.
OBJECTIVE: 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.

OBJECTIVE: This study is a systematic review of the literature which seeks to evaluate auditory and quality of life (QOL) outcomes of cochlear implantation in patients with Usher syndrome.
METHODS: Systematic review of studies indexed in Medline via PubMed, Ovid EMBASE, Web of Science, CENTRAL and clinicaltrials.gov was performed up to March 9th 2022, conducted in accordance with the PRISMA statement. Patient demographics, comorbidity, details of cochlear implantation, auditory, and QOL outcomes were extracted and summarized.
RESULTS: 33 studies reported over 217 cochlear implants in 187 patients with Usher syndrome, comprising subtypes 1 (56 patients), 2 (9 patients), 3 (23 patients), and not specified (99 patients). Auditory outcomes included improved sound detection, speech perception, and speech intelligibility. QOL outcomes were reported for 75 patients, with benefit reported in the majority.
CONCLUSIONS: Many patients with Usher syndrome develop improved auditory outcomes after cochlear implantation with early implantation being an important factor.

Adaptive optics (AO) imaging enables direct, objective assessments of retinal cells. Applications of AO show great promise in advancing our understanding of the etiology of inherited retinal disease (IRDs) and discovering new imaging biomarkers. This scoping review systematically identifies and summarizes clinical studies evaluating AO imaging in IRDs. Ovid MEDLINE and EMBASE were searched on February 6, 2023. Studies describing AO imaging in monogenic IRDs were included. Study screening and data extraction were performed by 2 reviewers independently. This review presents (1) a broad overview of the dominant areas of research; (2) a summary of IRD characteristics revealed by AO imaging; and (3) a discussion of methodological considerations relating to AO imaging in IRDs. From 140 studies with AO outcomes, including 2 following subretinal gene therapy treatments, 75% included fewer than 10 participants with AO imaging data. Of 100 studies that included participants\' genetic diagnoses, the most common IRD genes with AO outcomes are CNGA3, CNGB3, CHM, USH2A, and ABCA4. Confocal reflectance AO scanning laser ophthalmoscopy was the most reported imaging modality, followed by flood-illuminated AO and split-detector AO. The most common outcome was cone density, reported quantitatively in 56% of studies. Future research areas include guidelines to reduce variability in the reporting of AO methodology and a focus on functional AO techniques to guide the development of therapeutic interventions.

Usher syndrome (USH) is a genetically heterogeneous group of autosomal recessive (AR) syndromic inherited retinal degenerations (IRDs) representing 50% of deaf-blindness. All subtypes include retinitis pigmentosa, sensorineural hearing loss, and vestibular abnormalities. Thorough phenotyping may facilitate genetic diagnosis and intervention. Here we report the clinical/genetic features of an Irish USH cohort.
USH patients were selected from the Irish IRD registry (Target 5000). Patients were examined clinically (deep-phenotyping) and genetically using a 254 IRD-associated gene target capture sequencing panel, USH2A exon, and whole genome sequencing.
The study identified 145 patients (24.1% USH1 [n = 35], 73.8% USH2 [n = 107], 1.4% USH3 [n = 2], and 0.7% USH4 [n = 1]). A genetic diagnosis was reached in 82.1%, the majority (80.7%) being MYO7A or USH2A genotypes. Mean visual acuity and visual field (VF) were 0.47 ± 0.58 LogMAR and 31.3° ± 32.8°, respectively, at a mean age of 43 years. Legal blindness criteria were met in 40.7%. Cataract was present in 77.4%. ADGRV1 genotypes had the most VF loss, whereas USH2A patients had greater myopia and CDH23 had the most astigmatism. Variants absent from gnomAD non-Finnish Europeans and ClinVar represented more than 20% of the variants identified and were detected in ADGRV1, ARSG, CDH23, MYO7A, and USH2A.
USH is a genetically diverse group of AR IRDs that have a profound impact on affected individuals and their families. The prevalence and phenotype/genotype characteristics of USH in Ireland have, as yet, gone unreported. Understanding the genotype of Irish USH patients may guide clinical and genetic characterization facilitating access to existing/novel therapeutics.

This review considers research into the treatment of Usher syndrome, a deaf-blindness syndrome inherited in an autosomal recessive manner. Usher syndrome mutations are markedly heterogeneous, involving many different genes, and research grants are limited due to minimal patient populations. Furthermore, gene augmentation therapies are impossible in all but three Usher syndromes as the cDNA sequence exceeds the 4.7 kb AAV packaging limit. It is, therefore, vital to focus research efforts on alternative tools with the broadest applicability. The CRISPR field took off in recent years following the discovery of the DNA editing activity of Cas9 in 2012. New generations of CRISPR tools have succeeded the original CRISPR/Cas9 model to enable more sophisticated genomic amendments such as epigenetic modification and precise sequence alterations. This review will evaluate the most popular CRISPR tools to date: CRISPR/Cas9, base editing, and prime editing. It will consider these tools in terms of applicability (in relation to the ten most prevalent USH2A mutations), safety, efficiency, and in vivo delivery potential with the intention of guiding future research investment.

Usher syndrome (USH) is an autosomal recessive disorder that predominantly affects hearing, vision, and, in some cases, vestibular function. USH, according to the onset age, severity, and progression of symptoms, is categorized into four main types. In addition, there are a significant number of reports that patients\' manifestations deviate from canonical phenotypic criteria of main types of USH, which are named atypical USH. CDH23 is the second most common USH gene in which its defects result in USH1D, non-syndromic autosomal recessive deafness-12 (DFNB12), and in a few cases, atypical USH1D. While some studies have suggested that missense and truncating damaging variants in the CDH23 gene cause DFNB12 and USH1D, respectively, no genotype-phenotype correlation for atypical USH1D has been established.
Using whole-exome sequencing, we studied an Iranian family with two affected siblings who manifested congenital bilateral hearing loss, late-onset nyctalopia, retinitis pigmentosa, and normal vestibular function, indicating that their clinical symptoms are consistent with USH2.
Whole-exome data analysis revealed a novel bi-allelic nonsense variant (c.6562G>T; p.Glu2188Ter) in the CDH23 gene, which was confirmed by Sanger sequencing. Surprisingly, CDH23 is a member of the USH1 genes; therefore, our patients suffered from atypical USH1D. Also, by conducting a literature review, we provided a clinical and mutational profile of all reported patients with atypical manifestations or those who refuted the claimed genotype-phenotype correlation.
By reporting a novel damaging variant, we expand the mutational spectrum of the CDH23 gene that leads to atypical USH1D. Also, reviewing the literature shows that, contrary to previous claims, different genotypes occur in the CDH23 gene allelic disorders, and there is no clear-cut genotype-phenotype correlation.

Inherited retinal dystrophies (IRDs) are a group of rare diseases involving more than 340 genes and a variety of clinical phenotypes that lead to significant visual impairment. The aim of this study is to evaluate the rates and genetic characteristics of IRDs in the southeastern region of the United States (US). A retrospective chart review was performed on 325 patients with a clinical diagnosis of retinal dystrophy. Data including presenting symptoms, visual acuity, retinal exam findings, imaging findings, and genetic test results were compiled and compared to national and international IRD cohorts. The known ethnic groups included White (64%), African American or Black (30%), Hispanic (3%), and Asian (2%). The most prevalent dystrophies identified clinically were non-syndromic retinitis pigmentosa (29.8%), Stargardt disease (8.3%), Usher syndrome (8.3%), cone-rod dystrophy (8.0%), cone dystrophy (4.9%), and Leber congenital amaurosis (4.3%). Of the 101 patients (31.1%) with genetic testing, 54 (53.5%) had causative genetic variants identified. The most common pathogenic genetic variants were USH2A (n = 11), ABCA4 (n = 8), CLN3 (n = 7), and CEP290 (n = 3). Our study provides initial information characterizing IRDs within the diverse population of the southeastern US, which differs from national and international genetic and diagnostic trends with a relatively high proportion of retinitis pigmentosa in our African American or Black population and a relatively high frequency of USH2A pathogenic variants.

Usher syndrome (USH) is an autosomal recessive disorder characterized by sensorineural hearing loss, progressive pigmentary retinopathy, and vestibular dysfunction. The degree and onset of hearing loss vary among subtypes I, II, and III, while blindness often occurs in the second to fourth decades of life. Usher type III (USH3), characterized by postlingual progressive sensorineural hearing loss, varying levels of vestibular dysfunction, and varying degrees of visual impairment, typically manifests in the first to second decades of life. While USH3 is rare, it is highly prevalent in certain populations. RP61, USH3, and USH3A symbolize the same disorder, with the latter symbol used more frequently in recent literature. This review focuses on the clinical features, epidemiology, molecular genetics, treatment, and research advances for sensory deficits in USH3A.

Pathogenic variants in the CEP78 gene can present as atypical Usher syndrome or as retinitis pigmentosa. Here, we present a review of all reported cases of CEP78 variants in the literature to date and present a novel variant of CEP78, c.1261_1262delinsA, in a consanguineous northern Finnish family with two individuals.
Our patients were first discovered in a registry-based study. Later, they gave their written consent for this study. In order to describe the genotype and phenotype, their historic clinical patient data and genetic data were gathered, and a clinical ophthalmic examination and an audiogram were performed. For this review, a PubMed search using the keyword CEP78 was carried out. The first article on CEP78 was published in the year 2007, and the publications from the years 2007-2021 were included.
A large gene panel identified a homozygous CEP78 c.1261_1262delinsA variant in two affected siblings. In addition to the classical signs of retinitis pigmentosa, both siblings had large round atrophic spots in the mid periphery, and hyperautofluorescence of the macula. Patient 1 had age-related hearing impairment; patient 2 had normal hearing. In total, 20 articles have been published about CEP78. Eight of these papers report patient data with the affected individuals typically having retinal dystrophy combined with sensorineural hearing impairment, classified as atypical Usher syndrome.
Here, we present a comprehensive review of CEP78 and expand the knowledge of pathogenic CEP78 variants and the phenotypic variety.

Usher syndrome (USH) encompasses a group of clinically and genetically heterogenous disorders defined by the triad of sensorineural hearing loss (SNHL), vestibular dysfunction, and vision loss. USH is the most common cause of deaf blindness. USH is divided clinically into three subtypes-USH1, USH2, and USH3-based on symptom severity, progression, and age of onset. The underlying genetics of these USH forms are, however, significantly more complex, with over a dozen genes linked to the three primary clinical subtypes and other atypical USH phenotypes. Several of these genes are associated with other deaf-blindness syndromes that share significant clinical overlap with USH, pointing to the limits of a clinically based classification system. The genotype-phenotype relationships among USH forms also may vary significantly based on the location and type of mutation in the gene of interest. Understanding these genotype-phenotype relationships and associated natural disease histories is necessary for the successful development and application of gene-based therapies and precision medicine approaches to USH. Currently, the state of knowledge varies widely depending on the gene of interest. Recent studies utilizing next-generation sequencing technology have expanded the list of known pathogenic mutations in USH genes, identified new genes associated with USH-like phenotypes, and proposed algorithms to predict the phenotypic effects of specific categories of allelic variants. Further work is required to validate USH gene causality, and better define USH genotype-phenotype relationships and disease natural histories-particularly for rare mutations-to lay the groundwork for the future of USH treatment.