Long-Term Follow-Up before and during Riluzole Treatment in Six Patients from Two Families with Spinocerebellar Ataxia Type 7.

BACKGROUND: Currently no curative treatment exists for spinocerebellar ataxias (SCAs). Riluzole repurposing was proposed as a symptomatic treatment in different types of cerebellar ataxia. We report a long-term-follow up under riluzole treatment in SCA type 7. METHODS: Six patients received Riluzole 50 mg twice daily on a compassionate use program for a mean of 4.8 years (range 3.5-9). We measured ataxia onset and progression through the Scale for the Assessment and Rating of Ataxia (SARA), and collected extensive ophthalmological data before and after Riluzole treatment. Electrocardiogram and laboratory profile for drug safety were performed every six months. RESULTS: Riluzole treatment showed no effect on visual function in two patients with an advanced retinal damage. Improvements of visual function occurred in four patients followed by ophthalmologic stability up to 5 years after starting treatment. Two patients had a less steep deterioration of ataxia after treatment compared to pre-treatment, during the first 2,5 years of therapy. One showed soon after therapy an improvement of the SARA score, and then overall stability lasting 3,5 years, followed by ataxia worsening. One visually impaired patient without neurological impairment did not worse until the last visit after 3,5 years of follow-up. The remaining 2 patients showed an improvement of SARA scores soon after therapy, and an overall stability lasting respectively 5 and 3 years. No adverse event was registered during the observation period. DISCUSSION: This study suggests a possible beneficial action of Riluzole in SCA7 and provides a detailed description of the ophthalmologic profile of these patients.

Whole-Exome Sequencing in Turkish Patients with Inherited Retinal Dystrophies Reveals Novel Variants in Ten Genes.

Introduction: Inherited retinal dystrophies (IRDs) associated with more than 300 genes are a clinically and genetically heterogeneous group of retinal diseases. This study aimed to identify causative gene variants and molecular basis of Turkish patients with IRD. Methods: Whole-exome sequencing was performed in 28 unrelated patients. The potential pathogenicity of variants was evaluated using the American College of Medical Genetics variant interpretation guidelines, in silico prediction tools, published literature or Human Gene Mutation Database, and compatibility with inheritance patterns or known phenotypes. Results: Causative variants in 21 genes, including MERTK, SNRP200, MYO7A, AIPL1, RDH12, OTX2, ADGRV1, RPGRIP1, SPATA7, USH2A, MFSD8, CDHR1, EYS, CACNA1F, CNGA3, RDH5, TULP1, BBS2, BEST1, RS1, GUCY2D were detected in 26 (92.9%) of 28 patients. The most prevalent causative variants were observed MERTK (10.7% of cases), followed by CDHR1, AIPL1, RDH12, SPATA7, CNGA3, TULP1 (7.1% of cases, each). The most common variant type in this study was missense variants (53%), followed by frameshift (21%), nonsense (20%), and splice (6%). Twelve novel variants, 6 of frameshift and 6 of missense, were detected in ten genes. Retinitis pigmentosa was the most common phenotype followed by Leber congenital amaurosis. Conclusion: This study provides an overview of causative gene variants in Turkish patients with IRD. Variants identified in this study expand the variant spectrum of IRD genes. We believe it is essential to combine molecular and clinical data to diagnose IRD patients, especially with the emergence of therapeutic options.

Non-syndromic retinal dystrophy associated with biallelic variation of SUMF1 and reduced leukocyte sulfatase activity.

Biallelic variants in SUMF1 are associated with multiple sulfatase deficiency (MSD), a rare lysosomal storage disorder typically diagnosed in early infancy or childhood, marked by severe neurodegeneration and early mortality. We present clinical and molecular characterisation of three unrelated patients aged 13 to 58 years with milder clinical manifestations due to SUMF1 disease variants, including two adult patients presenting with apparent non-syndromic retinal dystrophy. Whole genome sequencing identified biallelic SUMF1 variants in all three patients; Patient 1 homozygous for a complex allele c.[290G>T;293T>A]; p.[(Gly97Val);(Val98Glu)], Patient 2 homozygous for c.866A>G; p.(Tyr289Cys), and Patient 3 compound heterozygous for c.726-1G>C and p.(Tyr289Cys). Electroretinography indicated a rod-cone dystrophy with additional possible inner retinal dysfunction in all three patients. Biochemical studies confirmed reduced, but not absent, sulfatase enzyme activity in the absence of extra-ocular disease (Patient 1) or only mild systemic disease (Patients 2, 3). These cases are suggestive that non-null SUMF1 genotypes can cause an attenuated clinical phenotype, including retinal dystrophy without systemic complications, in adulthood.

ABCA4-related retinopathies in Lebanon.

Variants in ATP-binding cassette transporter type A4 (ABCA4) have been linked to several forms of inherited retinal diseases (IRDs) besides the classically defined Stargardt disease (STGD), known collectively as ABCA4 retinopathies. ABCA4 is a sizable locus harboring 50 exons; thus, its analysis has revealed over 2,400 variants described, of which more than 2,000 are causal. Due to the clinical and genetic heterogeneity, diagnosing ABCA4 retinopathies is challenging. To date, no ABCA4-related retinopathy has been detected in Lebanon. Using next-generation sequencing, we analyzed our IRDs' cohort retrospectively (61 families) and identified five with ABCA4-related retinopathies, making it a relatively abundant cause of IRDs (about 8 %). Three families were diagnosed with rod-cone dystrophy (RCD), two with STGD, and one with cone-rod dystrophy (CRD). In conclusion, our study showed the presence of ABCA4 variants with a high degree of heterogeneity in Lebanon.

Next-generation sequencing to genetically diagnose a diverse range of inherited eye disorders in 15 consanguineous families from Pakistan.

Inherited retinal dystrophies (IRDs) are characterized by photoreceptor dysfunction or degeneration. Clinical and phenotypic overlap between IRDs makes the genetic diagnosis very challenging and comprehensive genomic approaches for accurate diagnosis are frequently required. While there are previous studies on IRDs in Pakistan, causative genes and variants are still unknown for a significant portion of patients. Therefore, there is a need to expand the knowledge of the genetic spectrum of IRDs in Pakistan. Here, we recruited 52 affected and 53 normal individuals from 15 consanguineous Pakistani families presenting non-syndromic and syndromic forms of IRDs. We employed single molecule Molecular Inversion Probes (smMIPs) based panel sequencing and whole genome sequencing to identify the probable disease-causing variants in these families. Using this approach, we obtained a 93% genetic solve rate and identified 16 (likely) causative variants in 14 families, of which seven novel variants were identified in ATOH7, COL18A1, MERTK, NDP, PROM1, PRPF8 and USH2A while nine recurrent variants were identified in CNGA3, CNGB1, HGSNAT, NMNAT1, SIX6 and TULP1. The novel MERTK variant and one recurrent TULP1 variant explained the intra-familial locus heterogeneity in one of the screened families while two recurrent CNGA3 variants explained compound heterozygosity in another family. The identification of variants in known disease-associated genes emphasizes the utilization of time and cost-effective screening approaches for rapid diagnosis. The timely genetic diagnosis will not only identify any associated systemic issues in case of syndromic IRDs, but will also aid in the acceleration of personalized medicine for patients affected with IRDs.

Retinoid Synthesis Regulation by Retinal Cells in Health and Disease.

Vision starts in retinal photoreceptors when specialized proteins (opsins) sense photons via their covalently bonded vitamin A derivative 11cis retinaldehyde (11cis-RAL). The reaction of non-enzymatic aldehydes with amino groups lacks specificity, and the reaction products may trigger cell damage. However, the reduced synthesis of 11cis-RAL results in photoreceptor demise and suggests the need for careful control over 11cis-RAL handling by retinal cells. This perspective focuses on retinoid(s) synthesis, their control in the adult retina, and their role during retina development. It also explores the potential importance of 9cis vitamin A derivatives in regulating retinoid synthesis and their impact on photoreceptor development and survival. Additionally, recent advancements suggesting the pivotal nature of retinoid synthesis regulation for cone cell viability are discussed.

Posterior microphthalmos with retinal involvement related to MFRP gene: a report of 10 Brazilian patients.

BACKGROUND: To describe the phenotype and genotype of 10 Brazilian patients with variants in MFRP, posterior microphthalmos and retinal findings. METHODS: Complete ophthalmological evaluation was done at 4 different Brazilian centers. Genetic analysis was performed using commercial next generation sequencing panels for inherited retinal disorders. RESULTS: Ages of the patients ranged from 10 to 65 years and visual acuities from 0,05 to no perception of light. All were hyperopes (+4,25 to + 17,50) with a short axial length (14,4 mm to 18 mm). Common posterior segment features, though not present in all, were optic disc drusen (5/10), foveoschisis (5/10) and retinal pigmentary changes (8/10). Isolated patients presented with macular atrophy, serous retinal detachment, and chorioretinal folds. The most common variant in MFRP found in our patients was a deletion in exon 5 (c.498delC; p.Asn267Thrfs *25), present in all except 2 patients. Other variants found were c.523C>T (p.Gln175*), c.298delG (p.Ala100Argfs *37), c.666del (p.Thr223Argfs *83) and the novel variant c.257C>A (p.Ala86Asp). CONCLUSIONS: This is the first report of Brazilian patients with posterior microphthalmos and pathogenic variants in MFRP and the first describe of the variant p.Ala86Asp in literature. Our cases confirm the previously reported phenotype of high hyperopia, optic disc drusen, alterations in foveal architecture, retinal pigmentary changes with loss of photoreceptor function and visual field constriction. Report of such a rare condition is important to increase awareness to the phenotype of posterior microphthalmia with associated retinal conditions.

Gyrate atrophy of the choroid and retina: Update on diagnosis and treatment.

Gyrate atrophy of the choroid and retina (GACR) is a rare autosomal recessive disease characterised by elevated plasma ornithine levels due to deficiency of the enzyme ornithine aminotransferase (OAT). The accumulation of this amino acid in plasma leads to the development of patches of chorioretinal atrophy in the peripheral retina extending into the macular area. Patients usually present with night blindness followed by constriction of the visual field and, finally, decreased central vision and blindness. The disease is diagnosed by the presence of the characteristic clinical picture, the presence of hyperornithinaemia in plasma and the detection of mutations in the OAT enzyme gene. There is currently no effective gene therapy and the most common therapeutic intervention mainly involves dietary modifications with arginine restriction. This article aims to summarise the pathogenesis, clinical and diagnostic findings and treatment options in patients with GACR.

Specific photoreceptor cell fate pathways are differentially altered in NR2E3-associated diseases.

Mutations in NR2E3, a gene encoding an orphan nuclear transcription factor, cause two retinal dystrophies with a distinct phenotype, but the precise role of NR2E3 in rod and cone transcriptional networks remains unclear. To dissect NR2E3 function, we performed scRNA-seq in the retinas of wildtype and two different Nr2e3 mouse models that show phenotypes similar to patients carrying NR2E3 mutations. Our results reveal that rod and cone populations are not homogeneous and can be separated into different sub-classes. We identify a previously unreported cone pathway that generates hybrid cones co-expressing both cone- and rod-related genes. In mutant retinas, this hybrid cone subpopulation is more abundant and includes a subpopulation of rods transitioning towards a cone cell fate. Hybrid photoreceptors with high misexpression of cone- and rod-related genes are prone to regulated necrosis. Overall, our results shed light on the role of NR2E3 in modulating photoreceptor differentiation towards cone and rod fates and explain how different mutations in NR2E3 lead to distinct visual disorders in humans.

Frequency and Distribution of Ophthalmic Surgical Procedures among Patients with Inherited Retinal Diseases.

OBJECTIVE: In this study, we aimed to characterize the frequency and distribution of ocular surgeries in patients with inherited retinal diseases (IRDs) and evaluate associated patient and disease factors. DESIGN: Retrospective cohort. PARTICIPANTS: Subjects aged ≥ 18 years who were followed at the Johns Hopkins Genetic Eye Disease Center. METHODS: We studied a retrospective cohort of patients with an IRD diagnosis to analyze the occurrence of laser and incisional surgeries. Subjects were categorized into 2 groups: central dysfunction (macular/cone/cone-rod dystrophy, "MCCRD group") and panretinal or peripheral dysfunction (retinitis pigmentosa-like, "RP group"). Genetic testing status was recorded. The association of patient and disease factors on the frequency, distribution, and timing of surgeries was analyzed. MAIN OUTCOME MEASURES: Prevalence, prevalence odds ratio (POR), hazard ratio (HR) of ophthalmic procedures by phenotype. RESULTS: A total of 1472 eyes of 736 subjects were evaluated. Among them, 31.3% (n = 230) had undergone ocular surgery, and 78.3% of those (n = 180/230) had a history of more than 1 surgery. A total of 602 surgical procedures were analyzed. Cataract extraction with intraocular lens implantation (CEIOL) was the most common (51.2%), followed by yttrium aluminum garnet capsulotomy, refractive surgery, retinal surgery, and others. Cataract extraction with intraocular lens implantation occurred more frequently in RP than in MCCRD subjects (POR, 2.59; P = 0.002). Retinitis pigmentosa subjects underwent CEIOL at a younger age than patients with MCCRD (HR, 2.11; P < 0.001). CONCLUSIONS: Approximately one-third of patients with IRD had a history of laser or incisional surgery. Cataract extraction with intraocular lens implantation was the most common surgery; its frequency and timing may be associated with the IRD phenotype. This data may inform the design of prospective research. Such efforts may illuminate routine clinical decision-making and contribute to surgical strategy development for cell and gene therapy delivery. FINANCIAL DISCLOSURE(S): Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Spectrum of variants associated with inherited retinal dystrophies in Northeast Mexico.

BACKGROUND: Inherited retinal dystrophies are hereditary diseases which have in common the progressive degeneration of photoreceptors. They are a group of diseases with clinical, genetic, and allelic heterogeneity. There is limited information regarding the genetic landscape of inherited retinal diseases in Mexico, therefore, the present study was conducted in the northeast region of the country. METHODS: Patients with inherited retinal dystrophies were included. A complete history, full ophthalmological and medical genetics evaluations, and genetic analysis through a targeted NGS panel for inherited retinal dystrophies comprising at least 293 genes were undertaken. RESULTS: A total of 126 patients were included. Cases were solved in 74.6% of the study's population. Retinitis pigmentosa accounted for the most found inherited retinal disease. Ninety-nine causal variants were found, being USH2A and ABCA4 the most affected genes (26 and 15 cases, respectively). CONCLUSIONS: The present study documents the most prevalent causative genes in IRDs, as USH2A, in northeastern Mexico. This contrasts with previous reports of IRDs in other zones of the country. Further studies, targeting previously unstudied populations in Mexico are important to document the genetic background of inherited retinal dystrophies in the country.

RP1 Dominant p.Ser740* Pathogenic Variant in 20 Knowingly Unrelated Families Affected by Rod-Cone Dystrophy: Potential Founder Effect in Western Sicily.

Background and Objectives. Retinitis pigmentosa (RP) is the most common inherited rod-cone dystrophy (RCD), resulting in nyctalopia, progressive visual field, and visual acuity decay in the late stages. The autosomal dominant form (ADRP) accounts for about 20% of RPs. Among the over 30 genes found to date related to ADRP, RP1 pathogenic variants have been identified in 5-10% of cases. In a cohort of RCD patients from the Palermo province on the island of Sicily, we identified a prevalent nonsense variant in RP1, which was associated with ADRP. The objective of our study was to analyse the clinical and molecular data of this patient cohort and to evaluate the potential presence of a founder effect. Materials and Methods. From 2005 to January 2023, 84 probands originating from Western Sicily (Italy) with a diagnosis of RCD or RP and their relatives underwent deep phenotyping, which was performed in various Italian clinical institutions. Molecular characterisation of patients and familial segregation of pathogenic variants were carried out in different laboratories using Sanger and/or next-generation sequencing (NGS). Results. Among 84 probands with RCD/RP, we found 28 heterozygotes for the RP1 variant c.2219C>G, p.Ser740* ((NM_006269.2)*, which was therefore significantly prevalent in this patient cohort. After a careful interview process, we ascertained that some of these patients shared the same pedigree. Therefore, we were ultimately able to define 20 independent family groups with no traceable consanguinity. Lastly, analysis of clinical data showed, in our patients, that the p.Ser740* nonsense variant was often associated with a late-onset and relatively mild phenotype. Conclusions. The high prevalence of the p.Ser740* variant in ADRP patients from Western Sicily suggests the presence of a founder effect, which has useful implications for the molecular diagnosis of RCD in patients coming from this Italian region. This variant can be primarily searched for in RP-affected subjects displaying compatible modes of transmission and phenotypes, with an advantage in terms of the required costs and time for analysis. Moreover, given its high prevalence, the RP1 p.Ser740* variant could represent a potential candidate for the development of therapeutic strategies based on gene editing or translational read-through therapy for suppression of nonsense variants.

Protocolo de tratamiento del edema macular quístico asociado a retinosis pigmentaria y otras distrofias hereditarias de la retina / Protocol for the treatment of cystoid macular edema secondary to retinitis pigmentosa and other inherited retinal dystrophies

Las distrofias hereditarias de la retina (DHR) son la causa principal de ceguera legal en la población laboral. El edema macular quístico (EMQ) es una de las causas tratables de pérdida visual afectando hasta un 50% de los pacientes. Se ha realizado una revisión bibliográfica combinando «inherited retinal dystrophy», «retinitis pigmentosa», «macular oedema» y un protocolo diagnóstico/terapéutico según los niveles de evidencia y recomendaciones de la «US Agency for Healthcare Research and Quality». Este protocolo se ha discutido en las reuniones mensuales del grupo XAREA DHR con la participación de más de 25 profesionales, creando un documento de consenso. La etiología del EMQ es multifactorial: disfunción de la barrera hematorretiniana, del epitelio pigmentario de la retina y de las células de Müller, inflamación y tracción vítrea. La OCT es la prueba de elección para el diagnóstico y seguimiento del EMQ asociado a las DHR. Los fármacos con mayor grado de evidencia científica son los inhibidores de la anhidrasa carbónica (IAC). Los corticoides, anti-VEGF intravítreos y vitrectomía con pelado de la membrana limitante interna no disponen de suficiente evidencia. Se propone un esquema de tratamiento en el EMQ en las DHR en adultos, otro para pacientes pediátricos y otra en las DHR y cirugía de catarata. Los IAC orales y tópicos son efectivos en el tratamiento del EMQ secundario a las DHR. El tratamiento con corticoides, anti-VEGF y vitrectomía son opciones de segunda línea. Se requieren ensayos clínicos aleatorizados para poder establecer la escala terapéutica en estos pacientes.(AU)

Inherited retinal dystrophies (IRD) are the leading cause of legal blindness in the working population. Cystic macular edema (CME) is one of the treatable causes of visual loss, affecting up to 50% of the patients. A bibliographic review has been carried out combining “inherited retinal dystrophy”, “retinitis pigmentosa”, “macular edema” and a diagnostic-therapeutic protocol according to the levels of evidence and recommendations of the “US Agency for Healthcare Research and Quality”. This protocol has been discussed in the monthly meetings of the XAREA DHR group with the participation of more than 25 experts, creating a consensus document. The etiology of CME is multifactorial: dysfunction of the blood-retinal barrier, retinal pigment epithelium, and Müller cells, inflammation, and vitreous traction.OCT is the test of choice for the diagnosis and follow-up of CME associated with IRD. The drugs with the highest degree of scientific evidence are carbonic anhydrase inhibitors (IAC). Intravitreal corticosteroids, anti-VEGF, and vitrectomy with peeling of the internal limiting membrane do not have sufficient evidence. A treatment scheme is proposed for the CME in IRD in adults, another for pediatric patients and an another for IRD and cataract surgery. Oral and topical IACs are effective in the treatment of CME secondary to IRD. Treatment with corticosteroids, anti-VEGF, and vitrectomy are second-line options. Randomized clinical trials are required to establish the therapeutic scale in these patients.(AU)

Real-World Safety and Effectiveness of Voretigene Neparvovec: Results up to 2 Years from the Prospective, Registry-Based PERCEIVE Study.

Voretigene neparvovec (VN) is the first available gene therapy for patients with biallelic RPE65-mediated inherited retinal dystrophy who have sufficient viable retinal cells. PERCEIVE is an ongoing, post-authorization, prospective, multicenter, registry-based observational study and is the largest study assessing the real-world, long-term safety and effectiveness of VN. Here, we present the outcomes of 103 patients treated with VN according to local prescribing information. The mean (SD) age was 19.5 (10.85) years, 52 (50.5%) were female, and the mean (SD) duration of the follow up was 0.8 (0.64) years (maximum: 2.3 years). Thirty-five patients (34%) experienced ocular treatment-emergent adverse events (TEAEs), most frequently related to chorioretinal atrophy (n = 13 [12.6%]). Eighteen patients (17.5%; 24 eyes [13.1%]) experienced ocular TEAEs of special interest, including intraocular inflammation and/or infection related to the procedure (n = 7). The mean (SD) changes from baseline in full-field light-sensitivity threshold testing (white light) at month 1, month 6, year 1, and year 2 were -16.59 (13.48) dB (51 eyes), -18.24 (14.62) dB (42 eyes), -15.84 (14.10) dB (10 eyes), and -13.67 (22.62) dB (13 eyes), respectively. The change in visual acuity from baseline was not clinically significant. Overall, the outcomes of the PERCEIVE study are consistent with the findings of VN pivotal clinical trials.

Protocol for the treatment of cystoid macular edema secondary to retinitis pigmentosa and other inherited retinal dystrophies.

Inherited retinal dystrophies (IRD) are the leading cause of legal blindness in the working population. Cystic macular edema (CME) is one of the treatable causes of visual loss, affecting up to 50% of the patients. A bibliographic review has been carried out combining "inherited retinal dystrophy", "retinitis pigmentosa", "macular oedema" and a diagnostic-therapeutic protocol according to the levels of evidence and recommendations of the "US Agency for Healthcare Research and Quality". This protocol has been discussed in the monthly meetings of the XAREA DHR group with the participation of more than 25 ophthalmologists, creating a consensus document. The etiology of CME is multifactorial: dysfunction of the blood-retinal barrier, retinal pigment epithelium, and Müller cells, inflammation, and vitreous traction. OCT is the test of choice for the diagnosis and follow-up of CME associated with IRD. The drugs with the highest degree of scientific evidence are carbonic anhydrase inhibitors (IAC). Intravitreal corticosteroids, anti-VEGF, and vitrectomy with peeling of the internal limiting membrane do not have sufficient evidence. A treatment scheme is proposed for the CME in IRD in adults, another for pediatric patients and another for IRD and cataract surgery. Oral and topical IACs are effective in the treatment of CME secondary to IRD. Treatment with corticosteroids, anti-VEGF, and vitrectomy are second-line options. Randomized clinical trials are required to establish the therapeutic scale in these patients.

Macular dystrophies associated with Stargardt-like phenotypes / Distrofias maculares associadas a fenótipos Stargardt-like

ABSTRACT Purpose: Stargardt-like phenotype has been described as associated with pathogenic variants besides the ABCA4 gene. This study aimed to describe four cases with retinal appearance of Stargardt disease phenotypes and unexpected molecular findings. Methods: This report reviewed medical records of four patients with macular dystrophy and clinical features of Stargardt disease. Ophthalmic examination, fundus imaging, and next-generation sequencing were performed to evaluate pathogenic variants related to the phenotypes. Results: Patients presented macular atrophy and pigmentary changes suggesting Stargardt disease. The phenotypes of the two patients were associated with autosomal dominant inheritance pattern genes (RIMS1 and CRX) and in the other two patients were associated with recessive dominant inheritance pattern genes (CRB1 and RDH12) with variants predicted to be pathogenic. Conclusion: Macular dystrophies may have phenotypic similarities to Stargardt-like phenotype associated with other genes besides the classic ones.

RESUMO Objetivo: Fenótipos Stargardt-like já foram asso-ciados a variantes patogênicas no gene ABCA4. O propósito desse estudo é descrever quatro pacientes com achados retinianos semelhantes a doença de Stargardt com resultados moleculares diferentes do esperado. Métodos: Esse relato fez a revisão de prontuários médicos de quatro pacientes com distrofia macular e achados clínicos sugestivos de doença de Stargardt. Foram realizados avaliação oftalmológica, exames de imagens e testes usando next generation sequencing para avaliar variantes patogênicas associadas aos fenótipos dos pacientes. Resultados: Os pacientes apresentavam atrofia macular e alterações pigmentares sugerindo achados clínicos de doença de Stargardt. Dois pacientes foram associados a genes com herança autossômica dominante (RIMS1 e CRX) e dois pacientes foram associados a genes com herança autossômica recessiva (CRB1 e RDH12) com variantes preditoras de serem patogênicas. Conclusão: Distrofias maculares podem ter similaridades fenotípicas com fenótipo de Stargardt-like associados a outros genes além dos classicamente já descritos.

The m6A reader YTHDC2 maintains visual function and retinal photoreceptor survival through modulating translation of PPEF2 and PDE6B.

Inherited retinal dystrophies (IRDs) are major causes of visual impairment and irreversible blindness worldwide, while the precise molecular and genetic mechanisms are still elusive. N6-methyladenosine (m6A) modification is the most prevalent internal modification in eukaryotic mRNA. YTH domain containing 2 (YTHDC2), an m6A reader protein, has recently been identified as a key player in germline development and human cancer. However, its contribution to retinal function remains unknown. Here, we explore the role of YTHDC2 in the visual function of retinal rod photoreceptors by generating rod-specific Ythdc2 knockout mice. Results show that Ythdc2 deficiency in rods causes diminished scotopic ERG responses and progressive retinal degeneration. Multi-omics analysis further identifies Ppef2 and Pde6b as the potential targets of YTHDC2 in the retina. Specifically, via its YTH domain, YTHDC2 recognizes and binds m6A-modified Ppef2 mRNA at the coding sequence and Pde6b mRNA at the 5'-UTR, resulting in enhanced translation efficiency without affecting mRNA levels. Compromised translation efficiency of Ppef2 and Pde6b after YTHDC2 depletion ultimately leads to decreased protein levels in the retina, impaired retinal function, and progressive rod death. Collectively, our finding highlights the importance of YTHDC2 in visual function and photoreceptor survival, which provides an unreported elucidation of IRD pathogenesis via epitranscriptomics.

An Optical Coherence Tomography-Based Measure as an Independent Estimate of Retinal Function in Retinitis Pigmentosa.

BACKGROUND: With the clinical advances in the field of gene therapy, the development of objective measures of visual function of patients with inherited retinal dystrophies (IRDs) is of utmost importance. Here, we propose one such measure. METHODS: We retrospectively analyzed data from a cohort of 194 eyes of 97 genetically diagnosed patients with retinitis pigmentosa (RP), the most common IRD, followed at the UPMC Vision Institute. The analyzed data included the reflectivity ratio (RR) of the retinal nerve fiber layer (RNFL) to that of the entire retina, visual acuity (VA) and the thickness of the retinal outer nuclear layer (ONL) and the RNFL. RESULTS: There was a strong positive correlation between the RR and VA. Both VA and the RR were negatively correlated with disease duration; VA, but not the RR, was negatively correlated with age. The RR correlated with the ONL but not with the RNFL thickness or the intraocular pressure. Age, RR, disease duration and ONL thickness were found to be independent predictors of VA by multivariate analysis. CONCLUSION: The OCT RR could serve as an independent predictor of visual acuity, and by extension of retinal function, in genetically diagnosed RP patients. Such objective measures can be of great value in patient selection for therapeutic trials.

Bridging Retinal and Cerebral Neurodegeneration: A Focus on Crosslinks between Alzheimer-Perusini's Disease and Retinal Dystrophies.

In the early stages of Alzheimer-Perusini's disease (AD), individuals often experience vision-related issues such as color vision impairment, reduced contrast sensitivity, and visual acuity problems. As the disease progresses, there is a connection with glaucoma and age-related macular degeneration (AMD) leading to retinal cell death. The retina's involvement suggests a link with the hippocampus, where most AD forms start. A thinning of the retinal nerve fiber layer (RNFL) due to the loss of retinal ganglion cells (RGCs) is seen as a potential AD diagnostic marker using electroretinography (ERG) and optical coherence tomography (OCT). Amyloid beta fragments (Aß), found in the eye's vitreous and aqueous humor, are also present in the cerebrospinal fluid (CSF) and accumulate in the retina. Aß is known to cause tau hyperphosphorylation, leading to its buildup in various retinal layers. However, diseases like AD are now seen as mixed proteinopathies, with deposits of the prion protein (PrP) and α-synuclein found in affected brains and retinas. Glial cells, especially microglial cells, play a crucial role in these diseases, maintaining immunoproteostasis. Studies have shown similarities between retinal and brain microglia in terms of transcription factor expression and morphotypes. All these findings constitute a good start to achieving better comprehension of neurodegeneration in both the eye and the brain. New insights will be able to bring the scientific community closer to specific disease-modifying therapies.

Application of Electrophysiology in Non-Macular Inherited Retinal Dystrophies.

Inherited retinal dystrophies encompass a diverse group of disorders affecting the structure and function of the retina, leading to progressive visual impairment and, in severe cases, blindness. Electrophysiology testing has emerged as a valuable tool in assessing and diagnosing those conditions, offering insights into the function of different parts of the visual pathway from retina to visual cortex and aiding in disease classification. This review provides an overview of the application of electrophysiology testing in the non-macular inherited retinal dystrophies focusing on both common and rare variants, including retinitis pigmentosa, progressive cone and cone-rod dystrophy, bradyopsia, Bietti crystalline dystrophy, late-onset retinal degeneration, and fundus albipunctatus. The different applications and limitations of electrophysiology techniques, including multifocal electroretinogram (mfERG), full-field ERG (ffERG), electrooculogram (EOG), pattern electroretinogram (PERG), and visual evoked potential (VEP), in the diagnosis and management of these distinctive phenotypes are discussed. The potential for electrophysiology testing to allow for further understanding of these diseases and the possibility of using these tests for early detection, prognosis prediction, and therapeutic monitoring in the future is reviewed.