X-linked Retinoschisis Research Articles

Identifying Multiomic Signatures of X-Linked Retinoschisis-Derived Retinal Organoids and Mice Harboring Patient-Specific Mutation Using Spatiotemporal Single-Cell Transcriptomics.

X-linked retinoschisis (XLRS) is an inherited retinal disorder with severe retinoschisis and visual impairments. Multiomics approaches integrate single-cell RNA-sequencing (scRNA-seq) and spatiotemporal transcriptomics (ST) offering potential for dissecting transcriptional networks and revealing cell-cell interactions involved in biomolecular pathomechanisms. Herein, a multimodal approach is demonstrated combining high-throughput scRNA-seq and ST to elucidate XLRS-specific transcriptomic signatures in two XLRS-like models with retinal splitting phenotypes, including genetically engineered (Rs1emR209C) mice and patient-derived retinal organoids harboring the same patient-specific p.R209C mutation. Through multiomics transcriptomic analysis, the endoplasmic reticulum (ER) stress/eukryotic initiation factor 2 (eIF2) signaling, mTOR pathway, and the regulation of eIF4 and p70S6K pathways are identified as chronically enriched and highly conserved disease pathways between two XLRS-like models. Western blots and proteomics analysis validate the occurrence of unfolded protein responses, chronic eIF2α signaling activation, and chronic ER stress-induced apoptosis. Furthermore, therapeutic targeting of the chronic ER stress/eIF2α pathway activation synergistically enhances the efficacy of AAV-mediated RS1 gene delivery, ultimately improving bipolar cell integrity, postsynaptic transmission, disorganized retinal architecture, and electrophysiological responses. Collectively, the complex transcriptomic signatures obtained from Rs1emR209C mice and patient-derived retinal organoids using the multiomics approach provide opportunities to unravel potential therapeutic targets for incurable retinal diseases, such as XLRS.

A retrospective longitudinal study of 52 Finnish patients with X-linked retinoschisis.

To describe clinical characteristics in Finnish patients with X-linked retinoschisis (XLRS) longitudinally with emphasis on retinal morphology and genotype-phenotype correlations. A retrospective cohort study reviewed medical records from patients with genetically confirmed XLRS from the Department of Ophthalmology, Helsinki University Hospital. Best-corrected visual acuity (BCVA), refraction, colour fundus photography, spectral-domain optical coherence tomography and genetic information were collected. Fifty-two males were diagnosed at the median age of 7 years (range 1-57) and followed for a median of 8 years (range, 1-49). Baseline findings included macular retinoschisis in 92(89%), macular atrophy in 25 (24%) and peripheral retinoschisis in 22 (21%) eyes. Vitreous haemorrhage occurred in 10 (10%) eyes, more frequently with peripheral schisis (p < 0.001). Nearly half of the patients, 22 (42%) were classified as visually impaired according to WHO. Median central retinal thickness was similar between initial (355 μm) and latest visits (360 μm) (p = 0.781). Low BCVA was associated with macular atrophy (p < 0.001), ellipsoid zone disruption (p = 0.007) and peripheral retinoschisis (p = 0.006). The three Finnish founder mutations c.214G >A, c.221G >T, and c.325G >C in exon 4 of retinoschisin 1 (RS1) were identified in 40 patients (77%). No associations were found between the genotypes and phenotypes. Three-fourths of the patients carried the Finnish founder mutations in RS1, but we did not detect any genotype-phenotype association. Macular atrophy was associated with the poorest visual acuity. Ocular compilations were associated with peripheral retinoschisis, suggesting that these patients should be followed more frequently.

An osmolarity dependent mechanism partially ameliorates retinal cysts and rescues cone function in a mouse model of X-linked retinoschisis.

X-linked retinoschisis (XLRS) is a vitreoretinal dystrophy caused by RS1 gene mutations which disrupt retinoschisin-1 (RS1) function. Vital for retinal architecture, the absence of functional RS1 leads to the development of intraretinal cysts. Intravitreal injection of a gene therapy for treating XLRS caused ocular inflammation in high dose groups in a phase I/II clinical trial. This study investigates a low dose subretinal gene therapy in Rs1 knockout (Rs1-KO) mice compared to injection of buffer alone. Observation of an unexpected therapeutic effect following the subretinal injection of the hypertonic buffer led to novel findings in XLRS. Rs1-KO mice were subretinally injected with an AAV2/4 vector (n = 10) containing the RS1 gene driven by an Ef1α promoter, a hypertonic buffer (n = 15) (180 mM NaCl 0.001% F68/PBS (pH 7.4)), or isotonic buffer (n = 7) (155.2 mM NaCl 0.001% F68/PBS, pH 7.0). A sham puncture group was also included (n = 6). Endpoints included electroretinogram (ERG), optical coherence tomography (OCT), a visually guided swim assay (VGSA), and immunohistochemistry. Unexpectedly, hypertonic buffer-injected eyes had reduced cyst severity at 1-month post-injection (MPI) (p < 0.0001), higher amplitudes in cone-dominant ERGs persisting to 5 MPI (5 Hz flicker; p < 0.0001; 3.0 flash; p = 0.0033) and a trend for improved navigational vision in the light compared to untreated Rs1-KO eyes. To investigate the role of tonicity on this effect, an isotonic buffer-injected cohort was created (155.2 mM NaCl 0.001% F68/PBS, pH 7.0) (n = 7). Surprisingly, hypertonic buffer-injected eyes exhibited a greater reduction in cyst severity and demonstrated improved cone-dominant ERG metrics over isotonic buffer-injected and sham puncture eyes. An immunohistochemistry assay demonstrated greater cone density in hypertonic buffer-injected eyes than untreated Rs1-KO eyes at 5-6 MPI (p = 0.0198), suggesting a possible cone preservation mechanism. Moreover, our findings reveal a negative correlation between the peak severity of cysts and long-term ERG amplitudes in cone-dominant pathways, implying that effectively managing cysts could yield enduring benefits for cone function. This study presents evidence that cyst resolution can be triggered through an osmolarity-dependent pathway, and early cyst resolution has long-term effects on cone signaling and survival, offering potential insights for the development of novel treatments for XLRS patients.

Novel unreported mutations in two cases of X-linked retinoschisis in Indian eye

We report two cases of X-linked retinoschisis (XLRS) with novel gene mutation. The first case revealed a hemizygous nonsense variant (c.440G&gt;A) in exon 5 of the RS1 gene and the second case revealed a hemizygous missense variant (c.286T&gt;G) in exon 4 of the RS1 gene. These gene mutations in XLRS are yet to be reported in published literature. Genetic mutations can have ethnic variations, and understanding novel mutations can help in genotype–phenotype correlation in a better way.

Introduction of an RS1 mutation causative variant consistent with identified XLRS patient using CRISPR/Cas9 technology in normal iPSC

X-linked retinoschisis (XLRS) is a common retinal genetic disease that occurs in juvenile males and causes progressive visual impairment. this presents a schisis in the macula or peripheral retina of bilateral eyes and currently has no effective treatment. Here, we introduced the RS1 (c.C304T, p.R102W) mutation into a normal induced pluripotent stem (iPS) cell line using CRISPR/Cas9 technology. This missense mutation was consistent with that observed in the XLRS patient-derived iPS cell line (CSUASOi001-A). Conclusively, establishing a directed gene mutation cell line (CSUi007-A) provides a useful cell resource to investigate XLRS pathogenesis.

Genotype–Phenotype Correlations in 83 Korean X-linked Retinoschisis Patients: Impact of Retinoschisin 1 Secretion Profiles on Clinical Phenotypes

To assess the correlation between genotype and phenotype severity in X-linked juvenile retinoschisis (XLRS) by examining clinical and genetic features of a cohort of Korean XLRS patients. Retrospective, observational study. Data from 83 consecutive male patients with molecularly confirmed XLRS were collected retrospectively. Clinical evaluation included best-corrected visual acuity (BCVA), fundus photography, spectral-domain optical coherence tomography (SD-OCT), and full-field electroretinography (ERG). The phenotypic characteristics of a cohort of pediatric Korean XLRS patients, based on mutation types (truncating versus missense) and secretory profile (secretion versus non-secretion), were assessed. One hundred sixty-six eyes of 83 patients were included. The mean age at diagnosis was 6.1 ± 8.8 years (range, 0.5-20.7 years), with a mean follow-up time of 9.2 ± 7.0 years (range, 0.6-24.3 years). The BCVA at first and last examination ranged from light perception to 0.1 logarithm of the minimum angle of resolution (mean ± SD, 0.75 ± 0.59 and 0.82 ± 0.65, respectively). There were no significant differences in the first and last BCVA measurements between the truncating (0.71 ± 0.51 and 0.75 ± 0.44) and missense (0.77 ± 0.59 and 0.84 ± 0.66) variants (P = 0.678 and 0.551, respectively). Additionally, there were no differences in clinical parameters from fundus photography, SD-OCT, and full-field ERG. However, the BCVA at the first and last measurement were better for patients in the secretion group (0.51 ± 0.24 and 0.61 ± 0.30) compared to patients in the non-secretion group (0.65 ± 0.71 and 0.87 ± 0.81). The last BCVA showed a statistically significant difference between the two groups (P = 0.021). In OCT findings, the frequency of ellipsoid zone disruption was higher in patients with non-secretion variants than those with secretion variants (P = 0.030), with no significant differences in other parameters. The secretion profile of RS1 could influence the severity of XLRS phenotypes. Patients with RS1-secreted mutants, particularly with intact octamerization, exhibit more homogeneous phenotypes and better visual acuity than the RS1-non-secreted group. This data provides insights for studying genotype and phenotype correlations in both clinical and research fields.

Peripapillary retinal nerve fibre layer thinning in patients with X-linked retinoschisis

AimsTo assess peripapillary retinal nerve fibre layer (pRNFL) thickness in patients with X-linked retinoschisis (XLRS), as pRNFL thinning may limit functional improvements in gene therapy trials.MethodsThis retrospective multicentre study included...

Frequency and Genetic Spectrum of Inherited Retinal Dystrophies in a Large Dutch Pediatric Cohort: The RD5000 Consortium.

Gene-based therapies for inherited retinal dystrophies (IRDs) are upcoming. Treatment before substantial vision loss will optimize outcomes. It is crucial to identify common phenotypes and causative genes in children. This study investigated the frequency of these in pediatric IRD with the aim of highlighting relevant groups for future therapy. Diagnostic, genetic, and demographic data, collected from medical charts of patients with IRD aged up to 20years (n = 624, 63% male), registered in the Dutch RD5000 database, were analyzed to determine frequencies of phenotypes and genetic causes. Phenotypes were categorized as nonsyndromic (progressive and stationary IRD) and syndromic IRD. Genetic causes, mostly determined by whole-exome sequencing (WES), were examined. Additionally, we investigated the utility of periodic reanalysis of WES data in genetically unresolved cases. Median age at registration was 13years (interquartile range, 9-16). Retinitis pigmentosa (RP; n = 123, 20%), Leber congenital amaurosis (LCA; n = 97, 16%), X-linked retinoschisis (n = 64, 10%), and achromatopsia (n = 63, 10%) were the most frequent phenotypes. The genetic cause was identified in 76% of the genetically examined patients (n = 473). The most frequently disease-causing genes were RS1 (n = 32, 9%), CEP290 (n = 28, 8%), CNGB3 (n = 21, 6%), and CRB1 (n = 17, 5%). Diagnostic yield after reanalysis of genetic data increased by 7%. As in most countries, RP and LCA are the most prominent pediatric IRDs in the Netherlands, and variants in RS1 and CEP290 were the most prominent IRD genotypes. Our findings can guide therapy development to target the diseases and genes with the greatest needs in young patients.

Waxing and waning course of X-linked bullous retinoschisis.

Waxing and waning course of X-linked bullous retinoschisis.

Early Developmental Characteristics and Features of a Three-Dimensional Retinal Organoid Model of X-Linked Juvenile Retinoschisis.

X-linked juvenile retinoschisis (XLRS) is a hereditary retinal degeneration affecting young males caused by mutations in the retinoschisin (RS1) gene. We generated human induced pluripotent stem cells (hiPSCs) from XLRS patients and established three-dimensional retinal organoids (ROs) for disease investigation. This disease model recapitulates the characteristics of XLRS, exhibiting defects in RS1 protein production and photoreceptor cell development. XLRS ROs also revealed dysregulation of Na/K-ATPase due to RS1 deficiency and increased ERK signaling pathway activity. Transcriptomic analyses of XLRS ROs showed decreased expression of retinal cells, particularly photoreceptor cells. Furthermore, relevant recovery of the XLRS phenotype was observed when co-cultured with control ROs derived from healthy subject during the early stages of differentiation. In conclusion, our in vitro XLRS RO model presents a valuable tool for elucidating the pathophysiological mechanisms underlying XLRS, offering insights into disease progression. Additionally, this model serves as a robust platform for the development and optimization of targeted therapeutic strategies, potentially improving treatment outcomes for patients with XLRS.

Investigating the role of Caspase-1 in a mouse model of Juvenile X-linked Retinoschisis

Investigating the role of Caspase-1 in a mouse model of Juvenile X-linked Retinoschisis

Retinal organoids with X-linked retinoschisis RS1 (E72K) mutation exhibit a photoreceptor developmental delay and are rescued by gene augmentation therapy

BackgroundX-linked juvenile retinoschisis (XLRS) is an inherited disease caused by RS1 gene mutation, which leads to retinal splitting and visual impairment. The mechanism of RS1-associated retinal degeneration is not fully understood. Besides, animal models of XLRS have limitations in the study of XLRS. Here, we used human induced pluripotent stem cell (hiPSC)-derived retinal organoids (ROs) to investigate the disease mechanisms and potential treatments for XLRS.MethodshiPSCs reprogrammed from peripheral blood mononuclear cells of two RS1 mutant (E72K) XLRS patients were differentiated into ROs. Subsequently, we explored whether RS1 mutation could affect RO development and explore the effectiveness of RS1 gene augmentation therapy.ResultsROs derived from RS1 (E72K) mutation hiPSCs exhibited a developmental delay in the photoreceptor, retinoschisin (RS1) deficiency, and altered spontaneous activity compared with control ROs. Furthermore, the delays in development were associated with decreased expression of rod-specific precursor markers (NRL) and photoreceptor-specific markers (RCVRN). Adeno-associated virus (AAV)-mediated gene augmentation with RS1 at the photoreceptor immature stage rescued the rod photoreceptor developmental delay in ROs with the RS1 (E72K) mutation.ConclusionsThe RS1 (E72K) mutation results in the photoreceptor development delay in ROs and can be partially rescued by the RS1 gene augmentation therapy.

Choroidal neovascularisation secondary toX-linked retinoschisis

AimsChoroidal neovascularisation (CNV) in patients with X-linked retinoschisis (XLRS) has been poorly documented. This study aims to investigate the prevalence and clinical characteristics of CNV in patients with XLRS, as...

Surgical repair of macular fold in X-linked retinoschisis initially misdiagnosed as familial exudative vitreoretinopathy

Purpose: To describe the presentation and surgical management of a young boy initially thought to have familial exudative vitreoretinopathy who was ultimately diagnosed with an unusually aggressive form of X-linked retinoschisis that included rapidly progressive bullous retinoschisis and tractional macular fold. Methods: Retrospective case report Results: A 19-month-old boy with straightening of major arcades, peripheral retinal ischemia, and in the left eye, a large macular fold was initially diagnosed as familial exudative vitreoretinopathy. During follow-up, he developed a rapidly progressive bullous retinoschisis in the left eye involving the inferior macula extending superiorly up to the macular fold. This revised the working diagnosis to X-linked retinoschisis, which was confirmed by genetic testing. Pars plana vitrectomy, inner flap retinectomy, unrolling of the macular fold and inner flap retinectomy, and C3F8 gas tamponade were performed. This resolved the macular fold. The patient showed good anatomical results without surgical complications up to 18 months of post-operative follow-up. Conclusions: X-linked retinoschisis can rarely present in young children with macular fold and peripheral ischemia, mimicking familial exudative vitreoretinopathy. Rapidly progressive bullous retinoschisis in this setting can be treated with pars plana vitrectomy, inner wall retinectomy, and removal of the vitreous traction to improve visual prognosis.

Генная терапия наследственных заболеваний сетчатки

This scientific literature review demonstrates high prospects of recent developments in gene therapy for the treatment of retinal diseases. First of all it concerns inherited pathologies such as retinitis pigmentosa and Leber congenital amaurosis. Nevertheless gene therapy is still quite far from its tangible application in clinical practice for other retinal diseases, although preliminary trial outcomes of its use for some of them (for example, achromatopsia, congenital X-linked retinoschisis) turn to be very promising. The data presented in this review inspire hope that gene therapy will be more accessible and widely-used in clinical practice. Key words:retinal diseases, inherited retinal diseases, gene therapy, voretigene neparvovec

Intravitreal Delivery of rAAV2-hSyn-hRS1 Results in Retinal Ganglion Cell-Specific Gene Expression and Retinal Improvement in the Rs1-KO Mouse.

X-linked retinoschisis (XLRS) is a monogenic recessive inherited retinal disease caused by defects in retinoschisin (RS1). It manifests clinically as retinal schisis cavities and a disproportionate reduction of b-wave amplitude compared with the a-wave amplitude. Currently there is no approved treatment. In the last decade, there has been major progress in the development of gene therapy for XLRS. Previous preclinical studies have demonstrated the treatment benefits of hRS1 gene augmentation therapy in mouse models. However, outcomes in clinical trials have been disappointing, and this might be attributed to dysfunctional assembly of RS1 complexes and/or the impaired targeted cells. In this study, the human synapsin 1 gene promoter (hSyn) was used to control the expression of hRS1 to specifically target retinal ganglion cells and our results confirmed the specific expression and functional assembly of the protein. Moreover, our results demonstrated that a single intravitreal injection of rAAV2-hSyn-hRS1 results in architectural restoration of retinal schisis cavities and improvement in vision in a mouse model of XLRS. In brief, this study not only supports the clinical development of the rAAV2-hSyn-hRS1 vector in XLRS patients but also confirms the therapeutic potential of rAAV-based gene therapy in inherited retinal diseases.

Experience in managing patients with X-linked congenital retinoschisis

AIM: To describe the clinical manifestations and management experience of patients with X-linked congenital retinoschisis (XLRS).&#x0D; MATERIAL AND METHODS: The study was conducted in the ophthalmology department of the multidisciplinary clinical medical center Bonum (Yekaterinburg). Two brothers with XLRS were under observation. They underwent complete ophthalmological examinations, including electrophysiological examinations, optical coherence tomography (OCT), and fundus photoregistration. The mother refused genetic testing.&#x0D; RESULTS: Both siblings had early (up to 1 year) manifestations of central foveolamellar and peripheral bullous retinoschisis. The parents are phenotypically healthy, and the relatives have no hereditary eye diseases. The younger brother had a progressive peripheral retinoschisis and underwent barrier laser retinopexy; as a result, the progression stopped at the last examination. Acetazolamide 125 mg given orally daily for 4 weeks did not have a noticeable effect on the volume of bullous cavities. The older brother had been under observation for 4 years, and spontaneous closure of retinal cavities on the periphery in one eye and retinal detachment in the other after surgical treatment of retinoschisis were observed.&#x0D; CONCLUSION: Clinical cases of long-term follow-up of two brothers with XLRS are described. OCT is indicated to diagnose, assess the length and the state of the vitreoretinal interface, and monitor XLRS. Electroretignography is a specific and sensitive method for the complex diagnosis of XLRS. Barrier laser retinopexy is indicated for progressive peripheral retinoschisis. The efficacy and safety of carbonic anhydrase inhibitors in patients with XLRS require further study.

Nationwide epidemiologic survey on incidence of macular dystrophy in Japan.

The aim of this study was to estimate the number of patients in Japan who had visited an ophthalmologist for macular dystrophy of various types, including Best vitelliform macular dystrophy (BVMD), Stargardt disease, occult macular dystrophy (OMD), cone (-rod) dystrophy, X-linked retinoschisis (XLRS), and central areolar choroid dystrophy (CACD). Nationwide epidemiologic survey METHODS: Questionnaires were distributed to 965 major facilities, including all the university hospitals in Japan. The aim of the questionnaire was to determine the number of patients with each type of macular dystrophy who had visited an outpatient clinic during the past 5 years (January 2015 to December 2019). Over 70% of the patients were diagnosed and followed up at university hospitals. The estimated annual number of newly diagnosed cases was as follows: 55.3 for BVMD, 36.7 for Stargardt disease, 35.8 for OMD, 160.6 for cone (-rod) dystrophy, 31.0 for XLRS, 29.8 for CACD, and 174.1 for other types of macular dystrophy. The total number of patients with macular dystrophy diagnosed and followed at major institutions was estimated to be 6651. This was the first nationwide survey of macular dystrophy in Japan and provided an approximate number of affected patients. The diagnosis of macular dystrophy is primarily carried out at facilities with affiliated specialists, such as university hospitals. By examining the incidence of multiple diseases simultaneously, we were able to compare the incidence of each type of macular dystrophy.

Dendritic opacified vessels in a case of X-linked retinoschisis

Dendritic opacified vessels in a case of X-linked retinoschisis

Photoreceptor deficits appear at eye opening in Rs1 mutant mouse models of X-linked retinoschisis

X-linked retinoschisis (XLRS) is an early onset degenerative retinal disease characterized by cystic lesions in the middle layers of the retina. These structural changes are accompanied by a loss of visual acuity and decreased contrast sensitivity. XLRS is caused by mutations in the gene Rs1 which encodes the secreted protein Retinoschisin 1. Young Rs1-mutant mouse models develop key hallmarks of XLRS including intraretinal schisis and abnormal electroretinograms. The electroretinogram (ERG) comprises activity of multiple cellular generators, and it is not known how and when each of these is impacted in Rs1 mutant mice. Here we use an ex vivo ERG system and pharmacological blockade to determine how ERG components generated by photoreceptors, ON-bipolar, and Müller glial cells are impacted in Rs1 mutants and to determine the time course of these changes. We report that ERG abnormalities begin near eye-opening and that all ERG components are involved.