Leber congenital amaurosis/early-onset severe retinal dystrophy: clinical features, molecular genetics and therapeutic interventions

Clinical, Ophthalmic, and Genetic Characterization of RPGRIP1-Associated Leber Congenital Amaurosis/Early-Onset Severe Retinal Dystrophy

PURPOSE

To present the clinical characteristics, retinal features, natural history, and genetics of RPGRIP1-associated early-onset severe retinal dystrophy (EOSRD)/Leber congenital amaurosis (LCA).

DESIGN

Retrospective case series.

METHODS

Review of clinical notes, multimodal retinal imaging, and molecular diagnosis of 18 patients (17 families) with EOSRD/LCA and disease-causing variants in RPGRIP1.

RESULTS

The mean age of visual symptoms onset was 0.87 ± 1 year (birth to 3 years), and the mean age at baseline visit was 11.4 ± 10.2 years (1-39 years). At the baseline visit, 44% of patients were legally blind (range, 2-39 years), and there was no significant association found between age and best-corrected visual acuity (BCVA) in cross-sectional analysis. Retinal evaluation showed an abolished electroretinogram or a cone-rod dystrophy pattern, no or minimal pigment deposits, a hyperautofluorescent ring at the posterior pole, and a largely preserved central macular architecture, with retained outer nuclear layer and ellipsoid zone island into adulthood. Eleven variants (48%) were previously unreported, and 13 families (76%) had a double-null (DN) genotype. Twelve patients (67%) had follow-up assessments over a 15.7 ± 9.5-year period. The rate of BCVA decline was 0.02 logarithm of the minimum angle of resolution (1 letter)/year.

CONCLUSIONS

RPGRIP1 EOSRD/LCA often presents at birth or early infancy, with nystagmus, decreased visual acuity, hyperopia, and photophobia. Patients with a DN genotype may develop symptoms earlier and have worse vision. Multimodal imaging may show a hyperautofluorescent posterior pole ring and relatively preserved central macular architecture, suggesting that the condition is a promising candidate for gene supplementation.

Clinical and Molecular Characterization of AIPL1-Associated Leber Congenital Amaurosis/Early-Onset Severe Retinal Dystrophy

PURPOSE

This study aimed to characterize the clinical features, genetic findings, and genotype-phenotype correlations of patients with Leber congenital amaurosis (LCA) or early-onset severe retinal dystrophy (EOSRD) harboring biallelic AIPL1 pathogenic variants.

DESIGN

Retrospective case series.

METHODS

This study consecutively enrolled 51 patients from 47 families with a clinical diagnosis of LCA/EOSRD harboring disease-causing variants in the AIPL1 gene, from October 2021 to September 2023. Molecular genetic findings, medical history, and ophthalmic evaluation including visual acuity (VA), multimodal retinal imaging, and electrophysiologic assessment were reviewed.

RESULTS

Of the 51 patients (32 with LCA and 19 with EOSRD), 27 (53%) were females, and age at last review ranged from 0.5 to 58.4 years. We identified 28 disease-causing AIPL1 variants, with 18 being novel. In patients with EOSRD, the mean (range) VA was 1.3 (0.7-2.7) logMAR and 1.3 (0.5-2.3) logMAR for right and left eyes respectively, with an average annual decline of 0.03 logMAR (R2 = 0.7547, P < .01). For patients with LCA, the VA ranged from light perception to counting fingers. Optical coherence tomography imaging demonstrated preservation of foveal ellipsoid zone in the 5 youngest EOSRD patients and 9 LCA children. Electroretinography showed severe cone-rod patterns in 78.6% (11/14) of patients with EOSRD, while classical extinguished pattern was documented in all patients with LCA available for the examination. The most common mutation was the nonsense variants of c.421C>T, with an allele frequency of 53.9%. All patients with EOSRD carried at least one missense mutation, of whom 13 identified with c.152A>G and 5 with c.572T>C. Twenty-six patients with LCA harbored two null AIPL1 variants, while 18 were homozygous for c.421C>T and 6 were heterozygous for c.421C>T with another loss-of-function variant.

CONCLUSIONS

This study reveals distinct clinical features and variation spectrum between AIPL1-associated LCA and EOSRD. Patients harboring at least one nonnull mutation, especially c.152A>G and c.572T>C, were significantly more likely to have a milder EOSRD phenotype than those with two null mutations. Residual foveal outer retinal structure observed in the youngest proportion of patients suggests an early window for gene augmentation therapy.

Safety and efficacy of ATSN-101 in patients with Leber congenital amaurosis caused by biallelic mutations in GUCY2D: a phase 1/2, multicentre, open-label, unilateral dose escalation study

BACKGROUND

Leber congenital amaurosis 1 (LCA1), caused by mutations in GUCY2D, is a rare inherited retinal disease that typically causes blindness in early childhood. The aim of this study was to evaluate the safety and preliminary efficacy of ascending doses of ATSN-101, a subretinal AAV5 gene therapy for LCA1.

METHODS

15 patients with genetically confirmed biallelic mutations in GUCY2D were included in this phase 1/2 study. All patients received unilateral subretinal injections of ATSN-101. In the dose-escalation phase, three adult cohorts (n=3 each) were treated with three ascending doses: 1·0 × 1010 vg/eye (low dose), 3·0 × 1010 vg/eye (middle dose), and 1·0 × 1011 vg/eye (high dose). In the dose-expansion phase, one adult cohort (n=3) and one paediatric cohort (n=3) were treated at the high dose. The primary endpoint was the incidence of treatment-emergent adverse events (TEAEs), and secondary endpoints included full-field stimulus test (FST) and best-corrected visual acuity (BCVA). A multi-luminance mobility test (MLMT) was also done. Data through the 12-month main study period are reported.

FINDINGS

Patients were enrolled between Sept 12, 2019, and May 5, 2022. A total of 68 TEAEs were observed, 56 of which were related to the surgical procedure. No serious TEAE was related to the study drug. Ocular inflammation was mild and reversible with steroid treatment. For patients who received the high dose, mean change in dark-adapted FST was 20·3 decibels (dB; 95% CI 6·6 to 34·0) for treated eyes and 1·1 dB (-3·7 to 5·9) for untreated eyes at month 12 (white stimulus); improvements were first observed at day 28 and persisted over 12 months (p=0·012). Modest improvements in BCVA were also observed (p=0·10). Three of six patients who received the high dose and did the MLMT achieved the maximum score in the treated eye.

INTERPRETATION

ATSN-101 is well tolerated 12 months after treatment, with no drug-related serious adverse events. Clinically significant improvements in retinal sensitivity were sustained in patients receiving the high dose.

FUNDING

Atsena Therapeutics.

Screening for Autism Spectrum Disorder in Children and Adolescents With Leber's Congenital Amaurosis

PURPOSE

To investigate autism spectrum disorder (ASD) indicators in children with Leber congenital amaurosis (LCA).

STUDY DESIGN

Cross-sectional, prospective, and correlational study.

METHODS

Setting: It was conducted at the Institute of Ocular Genetics, the Department of Ophthalmology at Federal University of São Paulo (UNIFESP), and the Autism Spectrum Disorder Laboratory, in São Paulo, Brazil.

PATIENT POPULATION

Participants included patients aged 2 to 16 years with LCA confirmed by genetic testing. There were 20 individuals with ciliopathies (LCA cilio) and 26 with other gene mutations (LCA other). As intervention, the instrument used for ASD screening was the Autism Behavior Checklist (ABC). Marginal descriptive analyses, non-parametric tests, and a linear regression model were conducted. The main outcomes were the scores on the tests correlated with clinical variables.

RESULTS

Of the 46 participants, 6 had ASD scores. There was no statistically significant correlation between the different groups (LCA cilio and LCA other) (p = 0.438). There was no statistically significant correlation between age and ASD (p = 0.308). However, there was a statistically significant correlation between visual acuity and ASD (p = 0.008) and between male gender and ASD (p = 0.025).

CONCLUSIONS

This study suggests that there is no correlation between LCA cilio, LCA other and ASD. These findings bring new insights to the existing literature, which previously lacked robust data on the relationship between LCA and ASD. These data demonstrate that visual acuity plays a crucial role in the development of children with visual impairment as poorer visual acuity is associated with a higher incidence of ASD. Based on this study, early interventions can be designed, especially for individuals without light perception, with the aim of maximizing their developmental outcomes. Furthermore, such data indicates that any improvement in visual acuity outcomes in treatment clinical trials become relevant for child development. NOTE: Publication of this article is sponsored by the American Ophthalmological Society.

Congenital Stationary Night Blindness: Structure, Function and Genotype-Phenotype Correlations in a Cohort of 122 Patients

OBJECTIVE

To examine the molecular causes of Schubert-Bornschein (S-B) congenital stationary night blindness (CSNB), clinically characterize in detail, and assess genotype-phenotype correlations for retinal function and structure.

DESIGN

Retrospective, longitudinal, single-center case series.

PARTICIPANTS

One hundred twenty-two patients with S-B CSNB attending Moorfields Eye Hospital, United Kingdom.

METHODS

All case notes, results of molecular genetic testing, and OCT were reviewed.

MAIN OUTCOME MEASURES

Molecular genetics, presenting complaints, rates of nystagmus, nyctalopia, photophobia, strabismus, color vision defects and spherical equivalent refraction (SER). Retinal thickness, outer nuclear layer (ONL) thickness, and ganglion cell layer + inner plexiform layer (GCL+IPL) thickness from OCT imaging.

RESULTS

X-linked (CACNA1F and NYX) and autosomal recessive (TRPM1, GRM6, GPR179 and CABP4) genotypes were identified. The mean (± standard deviation) reported age of onset was 4.94 ± 8.99 years. Over the follow-up period, 95.9% of patients reported reduced visual acuity (VA), half had nystagmus, and 64.7% reported nyctalopia. Incomplete CSNB (iCSNB) patients more frequently had nystagmus and photophobia. Nyctalopia was similar for iCSNB and complete CSNB (cCSNB). Color vision data were limited but more defects were found in iCSNB. None of these clinical differences met statistical significance. There was no significant difference between groups in VA, with a mean of 0.46 logarithm of the minimum angle of resolution, and VA remained stable over the course of follow-up. Complete congenital stationary night blindness patients, specifically those with NYX and TRPM1 variants, were more myopic. CACNA1F patients showed the largest refractive variability, and the CABP4 patient was hyperopic. No significant differences were found in OCT structural analysis during the follow-up period.

CONCLUSIONS

Retinal structure in CSNB is stationary and no specific genotype-structure correlates were identified. Visual acuity seems to be relatively stable, with rare instances of progression.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Clinical and genetic studies for a cohort of patients with Leber congenital amaurosis

PURPOSE

Leber congenital amaurosis (LCA) is a group of early-onset retinal degenerative disorders, resulting in blindness in children. This study aimed to describe the clinical and genetic characteristics of a cohort of patients with LCA and to investigate the retinal vascular characteristics in LCA patients.

METHODS

Fifty-two children with LCA were included in the study. All patients underwent detailed ocular examinations. Electroretinography (ERG) was used to evaluate the retinal function. Optical coherence tomography (OCT) was used to assess the structure change of the retina for those patients who were able to cooperate very well. Panel-based next-generation sequencing was performed to identify pathogenic variants in genes associated with LCA. Diameters of the retinal vessels were measured using the EVision AI screening system with an artificial intelligence (AI) technique. An ultrasound Doppler was used to evaluate hemodynamic parameters, including peak systolic velocity (PSV), resistive index (RI), and pulsatility index (PI), in the ophthalmic, central retinal, posterior ciliary, carotid, and internal carotid as well as external carotid arteries in 12 patients aged from 3 to 14 years.

RESULTS

We detected 75 pathogenic variants from ten genes of RPGRIP1, CEP290, GUCY2D, LCA5, AIPL1, CRB1, RPE65, CRX, RDH12, and TULP1, including 29 novel and 36 previously reported variants in 52 affected children with LCA, with the highest detective rate in RPGRIP1 (26.9%). Fundus appearance is diverse in patients with LCA, ranging from normal to severe peripheral or central retinopathy. Retinal vasculature was evaluated in 12 patients with different gene variants, showing narrowed arteries with an average diameter of 43.6 ± 3.8 μm compared to that of 51.7 ± 2.6 μm in the normal controls (P < 0.001, n = 12). Meanwhile, their hemodynamic parameters were changed as well in the ophthalmic artery (OA), with a decreased PSV (P = 0.0132, n = 12) and slightly increased PI (P = 0.0488, n = 12) compared to the normal controls. However, the hemodynamic parameters did not change significantly in the other vessels.

CONCLUSIONS

Blood supply to the eyeball is predicted to be reduced in patients with LCA, presumably due to photoreceptor cell degeneration. The novel identified variants will expand the spectrum of variants in LCA-related genes and be useful for studying the molecular mechanisms of LCA.

Estimating Australian Population Utilities for Inherited Retinal Disease Using Time Trade-Off

PURPOSE

Inherited retinal disease (IRD) causes progressive loss of visual function, degenerating towards complete blindness. Economic evaluation of gene therapies for rare forms of genetic IRDs have had to rely on health-related quality of life (HR-QoL) estimates from other diseases because there is limited data available for such a rare condition. This study aimed to estimate Australian societal-based utility values for IRD health states that can be used in cost-utility analyses (CUA) using a time trade-off (TTO) protocol adapted from a UK study.

METHODS

The EuroQol Valuation Technology (EQVT) protocol composite TTO (cTTO) framework was followed, which includes worse-than-death (WTD) states and quality control (QC) measures. Preferences were collected from a general population sample of 110 Australian adult participants. Five health state vignettes from the UK study which had been validated with patients and clinicians were presented randomly to participants during videoconferencing (VC) interviews with one of four interviewers. Technical and protocol feasibility were assessed in a pilot of 10 interviews. QC measures were used to monitor interviewers' performance during the study.

RESULTS

One participant withdrew consent. The final analysis was conducted on 109 respondents (including 4 non-traders). The average time to complete the interview was 44.2 minutes (SD 8.7). Participants reported mean visual analogue scale (VAS) scores between 63.15 for 'moderate impairment' and 17.98 for 'hand motion' to 'no light perception'. Mean health state utilities (HSU) varied between 0.76 (SD 0.26) in 'moderate impairment', and 0.20 (SD 0.58) in 'hand motion' to 'no light perception'. Of all HSU evaluations, 14% were considered WTD which most commonly occurred in the most severe visually impaired health state.

CONCLUSION

This study provides valuable information on HSUs across a range of IRD health states from the Australian general population perspective. The utilities obtained in this study can be used as inputs into CUA of IRD therapies.

Relationship between genotype, phenotype, and refractive status in patients of inherited retinal degeneration

BACKGROUND

To elucidate the relationship between inherited retinal disease, visual acuity and refractive error development in Asian patients.

SUBJECTS

Five hundred phakic eyes with refractive data were analysed in this retrospective cohort. Diseases were categorized by clinical phenotypes, and the prevalent genotypes identified in the Taiwan Inherited Retinal Degeneration Project were analysed. Consecutive surveys in Taiwan have provided the rates of myopia in the general population.

RESULTS

No differences were observed among the disease phenotypes with respect to myopia (P = 0.098) and high myopia rates (P = 0.037). The comparison of refractive error between retinitis pigmentosa and diseases mainly affecting the central retina showed no difference, and the refraction analyses in diseases of different onset ages yielded no significance. Moreover, there was no difference in the myopia rate between the diseases and general population. Among the genotypes, a higher spherical equivalent was seen in RPGR and PROM1-related patients and emmetropic trends were observed in patients with CRB1 and PRPF31 mutations. Furthermore, significantly poorer visual acuity was found in ABCA4, CRB1 and PROM1-related patients, and more preserved visual acuity was seen in patients with EYS, USH2A, and RDH12 mutations.

CONCLUSIONS

No significant differences were observed in visual acuity, refractive state and myopia rate between patients with inherited retinal disease and the general population, and different subtypes of inherited retinal disease shared similar refractive state, except for higher cylindrical dioptres found in patients with Leber's congenital amaurosis. The heterogeneity of disease-causing genes in Asian patients may lead to variable refractive state.

IQCB1 (NPHP5)-Retinopathy: Clinical and Genetic Characterization and Natural History

PURPOSE

To describe the clinical and genetic features, and explore the natural history of retinopathy associated with IQCB1 variants in children and adults with retinopathy.

DESIGN

Retrospective cohort study at a single tertiary care referral center.

METHODS

The study recruited 19 patients with retinopathy, harboring likely disease-causing variants in IQCB1. Demographic data and clinical presentation, best corrected visual acuity (BCVA), fundus appearance, optical coherence tomography (OCT) and autofluorescence features, electroretinography (ERG) and molecular genetics are reported.

RESULTS

Ten patients had best corrected visual acuity better than 1.0 LogMAR, and BCVA remained stable till the last review. Seven patients had a vision of hand movements or worse in at least one eye at presentation. There was no correlation found between age of onset and severity of vision loss. Nine patients (47.4%) had a diagnosis of end-stage renal failure at presentation. The other 10 patients (52.6%) had a diagnosis of non-syndromic IQCB1-retinopathy and maintained normal renal function until the last follow-up. The mean age at diagnosis of renal failure was 26.3 ±19.8 years. OCT showed ellipsoid zone (EZ) disruption with foveal sparing in 8/13 patients. All patients had stable OCT findings. Full-field ERGs in four adults revealed a severe cone-rod dystrophy and three children had extinguished ERGs. We identified 17 IQCB1 variants, all predicted to cause loss of function.

CONCLUSION

IQCB1-retinopathy is a severe early-onset cone-rod dystrophy. The dissociation between severely decreased retinal function and relative preservation of retinal structure over a wide age window makes the disease a candidate for gene therapy.

Autozygome-guided exome-first study in a consanguineous cohort with early-onset retinal disease uncovers an isolated RIMS2 phenotype and a retina-enriched RIMS2 isoform

Leber congenital amaurosis (LCA) and early-onset retinal degeneration (EORD) are inherited retinal diseases (IRD) characterized by early-onset vision impairment. Herein, we studied 15 Saudi families by whole exome sequencing (WES) and run-of-homozygosity (ROH) detection via AutoMap in 12/15 consanguineous families. This revealed (likely) pathogenic variants in 11/15 families (73%). A potential founder variant was found in RPGRIP1. Homozygous pathogenic variants were identified in known IRD genes (ATF6, CRB1, CABP4, RDH12, RIMS2, RPGRIP1, SPATA7). We established genotype-driven clinical reclassifications for ATF6, CABP4, and RIMS2. Specifically, we observed isolated IRD in the individual with the novel RIMS2 variant, and we found a retina-enriched RIMS2 isoform conserved but not annotated in mouse. The latter illustrates potential different phenotypic consequences of pathogenic variants depending on the particular tissue/cell-type specific isoforms they affect. Lastly, a compound heterozygous genotype in GUCY2D in one non-consanguineous family was demonstrated, and homozygous variants in novel candidate genes ATG2B and RUFY3 were found in the two remaining consanguineous families. Reporting these genes will allow to validate them in other IRD cohorts. Finally, the missing heritability of the two unsolved IRD cases may be attributed to variants in non-coding regions or structural variants that remained undetected, warranting future WGS studies.

Objective Outcomes to Evaluate Voretigene Neparvovec Treatment Effects in Clinical Practice

PURPOSE

To assess the efficacy of voretigene neparvovec (VN) treatment by objective fixation stability and chromatic pupillometry testing in clinical practice.

DESIGN

Retrospective cohort study with longitudinal follow-up.

SUBJECTS

Twelve patients (aged 7-34 years) with RPE65-related inherited retinal dystrophies were treated at the same center with VN in both eyes.

METHODS

Patients treated at the same center with VN were evaluated over a 12-month posttreatment follow-up by subjective and objective tests. Furthermore, patients treated with VN who developed atrophy were compared with those who did not.

MAIN OUTCOME MEASURES

Best-corrected visual acuity (BCVA), full-field stimulus threshold test (FST), semiautomated kinetic visual field (SKVF), microperimetry, and chromatic pupillometry over a 12-month follow-up.

RESULTS

Significant improvements of BCVA (P < 0.001), SKVF (P < 0.05), and FST (P < 0.001) were already observed 45 days after treatment and were maintained at the 12-month timepoint. Fixation stability, assessed by microperimetry, improved significantly (P < 0.05) after treatment. Chromatic pupillometry showed significant improvements (P < 0.05) at the 6- and 12-month timepoints. The increase in maximum pupillary constriction significantly (P < 0.001) correlated with higher retinal sensitivity in FST. Four patients developed multifocal retinal atrophy in both eyes, detected at the 6-month timepoint, but this atrophy was not generally associated with worse visual function outcomes.

CONCLUSIONS

This study explores objective outcomes in order to demonstrate the efficacy of VN treatment in addition to the tests normally performed in clinical practice. Our findings show a significant improvement of retinal function both in subjective assessments, such as BCVA, SKVF, and FST, and in objective measurements of fixation stability and maximum pupillary constriction. Moreover, the significant correlation between maximum pupillary constriction and light sensitivity thresholds corroborates the introduction of chromatic pupillometry as an objective test to better assess treatment outcomes in patients with inherited retinal dystrophies.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found after the references in the Footnotes and Disclosures at the end of this article.

Modeling inherited retinal diseases using human induced pluripotent stem cell derived photoreceptor cells and retinal pigment epithelial cells

Since the discovery of induced pluripotent stem cell (iPSC) technology, there have been many attempts to create cellular models of inherited retinal diseases (IRDs) for investigation of pathogenic processes to facilitate target discovery and validation activities. Consistency remains key in determining the utility of these findings. Despite the importance of consistency, quality control metrics are still not widely used. In this review, a toolkit for harnessing iPSC technology to generate photoreceptor, retinal pigment epithelial cell, and organoid disease models is provided. Considerations while developing iPSC-derived IRD models such as iPSC origin, reprogramming methods, quality control metrics, control strategies, and differentiation protocols are discussed. Various iPSC IRD models are dissected and the scientific hurdles of iPSC-based disease modeling are discussed to provide an overview of current methods and future directions in this field.

Nationwide Prevalence of Inherited Retinal Diseases in the Israeli Population

Importance

Data regarding the prevalence of various inherited retinal diseases (IRDs) are limited and vary across populations; moreover, nationwide prevalence studies may be limited to a specific IRD phenotype, potentially leading to inaccurate prevalence estimations. Therefore, nationwide prevalence data are needed.

Objective

To determine the prevalence of 67 IRD phenotypes in the Israeli population.

Design, Setting, and Participants

This cohort study collected nationwide data regarding the number of individuals affected with IRD phenotypes assessed in 10 clinical and academic centers in Israel as part of the research activity of the Israeli inherited retinal disease consortium. Data were collected in May 2023 on 9396 individuals residing in Israel who were diagnosed by an ophthalmologist with an IRD using either electroretinography or retinal imaging where included. Individuals with retinal diseases known to have a nonmendelian basis or without a clear genetic basis and those who were reported as deceased at the time of data collection were excluded from this study.

Main Outcomes and Measures

Prevalence of 67 IRD phenotypes.

Results

Among the 9396 participants in our cohort, the most common IRD in Israel was retinitis pigmentosa with a disease prevalence of approximately 1:2400 individuals, followed by cone-rod dystrophy (approximately 1:14 000), Stargardt disease (approximately 1:16 000), Usher syndrome (approximately 1:16,000), and congenital stationary night blindness (approximately 1:18 000). The prevalence of all IRDs combined was 1:1043 individuals.

Conclusions and Relevance

The current study provides large prevalence dataset of 67 IRD phenotypes, some of which are extremely rare, with only a single identified case. This analysis highlights the potential importance of performing additional nationwide prevalence studies to potentially assist with determining the prevalence of IRDs worldwide.

Characteristics of Eyes With CRB1-Associated EOSRD/LCA: Age-Related Changes

PURPOSE

To evaluate ocular and retinal features of CRB1-associated early onset severe retinal dystrophy/Leber congenital amaurosis (EOSRD/LCA) for age-related changes.

DESIGN

Retrospective cohort study.

METHODS

Sixteen pediatric patients with biallelic CRB1 EOSRD/LCA who had been followed for up to 18 years were reviewed. Results of comprehensive ophthalmic examinations-including visual acuity, refractive error, dark-adapted visual threshold, Goldmann perimetry, and macular optical coherence tomography (OCT)-were analyzed for significant age-related changes using mixed-effects models.

RESULTS

Visual acuity dark-adapted visual sensitivity, and area of seeing visual field (all subnormal from the earliest ages recorded) declined with increasing age. Hyperopia was stable through childhood and adolescence. In CRB1 EOSRD/LCA, OCT extrafoveal inner and outer laminar thicknesses exceeded those in controls but varied little with age, and foveal metrics (depth, breadth, thickness at rim) differed significantly from those in controls, but variations in foveal metrics were not associated with declines in acuity.

CONCLUSIONS

From the youngest ages, retinal and visual function is significantly subnormal and becomes progressively compromized. A goal of future therapies should be intervention at young ages, when there is more function to be rescued.

Four Unique Genetic Variants in Three Genes Account for 62.7% of Early-Onset Severe Retinal Dystrophy in Chile: Diagnostic and Therapeutic Consequences

Leber congenital amaurosis (LCA)/early-onset severe retinal dystrophy (EOSRD) stand as primary causes of incurable childhood blindness. This study investigates the clinical and molecular architecture of syndromic and non-syndromic LCA/EOSRD within a Chilean cohort (67 patients/60 families). Leveraging panel sequencing, 95.5% detection was achieved, revealing 17 genes and 126 variants (32 unique). CRB1, LCA5, and RDH12 dominated (71.9%), with CRB1 being the most prevalent (43.8%). Notably, four unique variants (LCA5 p.Glu415*, CRB1 p.Ser1049Aspfs*40 and p.Cys948Tyr, RDH12 p.Leu99Ile) constituted 62.7% of all disease alleles, indicating their importance for targeted analysis in Chilean patients. This study underscores a high degree of inbreeding in Chilean families affected by pediatric retinal blindness, resulting in a limited mutation repertoire. Furthermore, it complements and reinforces earlier reports, indicating the involvement of ADAM9 and RP1 as uncommon causes of LCA/EOSRD. These data hold significant value for patient and family counseling, pharmaceutical industry endeavors in personalized medicine, and future enrolment in gene therapy-based treatments, particularly with ongoing trials (LCA5) or advancing preclinical developments (CRB1 and RDH12).

RPE65 mutations in Leber congenital amaurosis, early-onset severe retinal dystrophy, and retinitis pigmentosa from a tertiary eye care center in India

INTRODUCTION

Mutations in the retinal pigment epithelial 65 kilodalton protein (RPE65) gene are associated with various inherited retinal diseases (IRDs), including Leber congenital amaurosis (LCA), early-onset severe retinal dystrophy (EOSRD), and retinitis pigmentosa (RP). We screened for mutations in RPE65 in a series of Indian patients with these IRDs to determine the frequency/types of mutations and to describe the associated phenotypes.

MATERIALS AND METHODS

Diagnosis of LCA, EOSRD, and RP was made by standard and pre-defined criteria. Patients were evaluated by clinical, retinal imaging, and electrophysiological parameters. Genomic DNA from patients and available family members were used for identifying mutations by direct Sanger sequencing of the RPE65 gene or targeted NGS gene panel for IRDs covering 260+ genes. Variations detected were tested in healthy control populations and for co-segregation with the disease in available family members.

RESULTS

Mutations were found in eight patients, out of 220 total cases screened, all homozygous for the respective mutant alleles. Seven patients had mutations leading to premature termination codons and one patient had a missense change. The onset of visual loss ranged from birth to <2 years of life. At presentation, RPE mottling in the background retina was present in all cases with macular involvement in five cases with or without vascular attenuation and optic disc pallor.

CONCLUSION

RPE65 mutations in this series were found in 3.6% of cases associated with severe, early-onset disease, with consistent RPE mottling and variable manifestations with regard to the extent of disc pallor, arteriolar attenuation, and appearance of the macula.

Enhanced Learning and Memory in Patients with CRB1 Retinopathy

Mutations in the CRB1 gene are associated with a diverse spectrum of retinopathies with phenotypic variability causing severe visual impairment. The CRB1 gene has a role in retinal development and is expressed in the cerebral cortex and hippocampus, but its role in cognition has not been described before. This study compares cognitive function in CRB1 retinopathy individuals with subjects with other retinopathies and the normal population.

METHODS

Neuropsychological tests of cognitive function were used to test individuals with CRB1 and non-CRB1 retinopathies and compare results with a standardised normative dataset.

RESULTS

CRB1 retinopathy subjects significantly outperformed those with non-CRB1 retinopathy in list learning tasks of immediate (p = 0.001) and delayed memory (p = 0.007), tests of semantic verbal fluency (p = 0.017), verbal IQ digit span subtest (p = 0.037), and estimation test of higher execution function (p = 0.020) but not in the remaining tests of cognitive function (p > 0.05). CRB1 retinopathy subjects scored significantly higher than the normal population in all areas of memory testing (p < 0.05) and overall verbal IQ tests (p = 0.0012). Non-CRB1 retinopathy subjects scored significantly higher than the normal population in story recall, verbal fluency, and overall verbal IQ tests (p = 0.0016).

CONCLUSIONS

Subjects with CRB1 retinopathy may have enhanced cognitive function in areas of memory and learning. Further work is required to understand the role of CRB1 in cognition.

Retinol dehydrogenase 12 (RDH12) knock out may cause hyperuricemia phenotype in mice

Hyperuricemia is a chronic metabolic disease caused by purine metabolism disorder. And several gene loci and transporter proteins that associated with uric acid transport functions have been identified. Retinol Dehydrogenase 12 (RDH12), recognized for its role in safeguarding photoreceptors, and our study investigated the potential impact of Rdh12 mutations on other organs and diseases, particularly hyperuricemia. We assessed Rdh12 mRNA expression levels in various tissues and conducted serum biochemical analyses in Rdh12-/- mice. Compared with the wild type, significant alterations in serum uric acid levels and kidney-related biochemical indicators have been revealed. Then further analysis, including quantitative RT-PCR of gene expression in the liver and kidney, highlighted variations in the expression levels of specific genes linked to hyperuricemia. And renal histology assessment exposed mild pathological lesions in the kidneys of Rdh12-/- mice. In summary, our study suggests that Rdh12 mutations impact not only retinal function but also contribute to hyperuricemia and renal disease phenotypes in mice. Our finding implies that individuals with Rdh12 mutations may be prone to hyperuricemia and gout, emphasizing the significance of preventive measures and regular examinations in daily life.

Retinal microcirculation: A window into systemic circulation and metabolic disease

The retinal microcirculation system constitutes a unique terminal vessel bed of the systemic circulation, and its perfusion status is directly associated with the neural function of the retina. This vascular network, essential for nourishing various layers of the retina, comprises two primary microcirculation systems: the retinal microcirculation and the choroidal microcirculation, with each system supplying blood to distinct retinal layers and maintaining the associated neural function. The blood flow of those capillaries is regulated via different mechanisms. However, a range of internal and external factors can disrupt the normal architecture and blood flow within the retinal microcirculation, leading to several retinal pathologies, including diabetic retinopathy, macular edema, and vascular occlusions. Metabolic disturbances such as hyperglycemia, hypertension, and dyslipidemia are known to modify retinal microcirculation through various pathways. These alterations are observable in chronic metabolic conditions like diabetes, coronary artery disease, and cerebral microvascular disease due to advances in non-invasive or minimally invasive retinal imaging techniques. Thus, examination of the retinal microcirculation can provide insights into the progression of numerous chronic metabolic disorders. This review discusses the anatomy, physiology and pathophysiology of the retinal microvascular system, with a particular emphasis on the connections between retinal microcirculation and systemic circulation in both healthy states and in the context of prevalent chronic metabolic diseases.

Phenotyping and genotyping inherited retinal diseases: Molecular genetics, clinical and imaging features, and therapeutics of macular dystrophies, cone and cone-rod dystrophies, rod-cone dystrophies, Leber congenital amaurosis, and cone dysfunction syndromes

Inherited retinal diseases (IRD) are a leading cause of blindness in the working age population and in children. The scope of this review is to familiarise clinicians and scientists with the current landscape of molecular genetics, clinical phenotype, retinal imaging and therapeutic prospects/completed trials in IRD. Herein we present in a comprehensive and concise manner: (i) macular dystrophies (Stargardt disease (ABCA4), X-linked retinoschisis (RS1), Best disease (BEST1), PRPH2-associated pattern dystrophy, Sorsby fundus dystrophy (TIMP3), and autosomal dominant drusen (EFEMP1)), (ii) cone and cone-rod dystrophies (GUCA1A, PRPH2, ABCA4, KCNV2 and RPGR), (iii) predominant rod or rod-cone dystrophies (retinitis pigmentosa, enhanced S-Cone syndrome (NR2E3), Bietti crystalline corneoretinal dystrophy (CYP4V2)), (iv) Leber congenital amaurosis/early-onset severe retinal dystrophy (GUCY2D, CEP290, CRB1, RDH12, RPE65, TULP1, AIPL1 and NMNAT1), (v) cone dysfunction syndromes (achromatopsia (CNGA3, CNGB3, PDE6C, PDE6H, GNAT2, ATF6), X-linked cone dysfunction with myopia and dichromacy (Bornholm Eye disease; OPN1LW/OPN1MW array), oligocone trichromacy, and blue-cone monochromatism (OPN1LW/OPN1MW array)). Whilst we use the aforementioned classical phenotypic groupings, a key feature of IRD is that it is characterised by tremendous heterogeneity and variable expressivity, with several of the above genes associated with a range of phenotypes.

Ocular manifestations of renal ciliopathies

Renal ciliopathies are a common cause of kidney failure in children and adults, and this study reviewed their ocular associations. Genes affected in renal ciliopathies were identified from the Genomics England Panels. Ocular associations were identified from Medline and OMIM, and the genes additionally examined for expression in the human retina ( https://www.proteinatlas.org/humanproteome/tissue ) and for an ocular phenotype in mouse models ( http://www.informatics.jax.org/ ). Eighty-two of the 86 pediatric-onset renal ciliopathies (95%) have an ocular phenotype, including inherited retinal degeneration, oculomotor disorders, and coloboma. Diseases associated with pathogenic variants in ANK6, MAPKBP1, NEK8, and TCTN1 have no reported ocular manifestations, as well as low retinal expression and no ocular features in mouse models. Ocular abnormalities are not associated with the most common adult-onset "cystic" kidney diseases, namely, autosomal dominant (AD) polycystic kidney disease and the AD tubulointerstitial kidney diseases (ADTKD). However, other kidney syndromes with cysts have ocular features including papillorenal syndrome (optic disc dysplasia), Hereditary Angiopathy Nephropathy, Aneurysms and muscle Cramps (HANAC) (tortuous retinal vessels), tuberous sclerosis (retinal hamartomas), von Hippel-Lindau syndrome (retinal hemangiomas), and Alport syndrome (lenticonus, fleck retinopathy). Ocular abnormalities are associated with many pediatric-onset renal ciliopathies but are uncommon in adult-onset cystic kidney disease. However the demonstration of ocular manifestations may be helpful diagnostically and the features may require monitoring or treatment.

Adaptive Optics Retinal Imaging in RDH12-Associated Early Onset Severe Retinal Dystrophy

Purpose

RDH12 is among the most common genes found in individuals with early-onset severe retinal (EOSRD). Adaptive optics scanning light ophthalmoscopy (AOSLO) enables resolution of individual rod and cone photoreceptors in the retina. This study presents the first AOSLO imaging of individuals with RDH12-associated EOSRD.

Methods

Case series of patients who attended Moorfields Eye Hospital (London, UK). Spectral-domain optical coherence tomography, near-infrared reflectance (NIR), and blue autofluorescence imaging were analyzed. En face image sequences of photoreceptors were recorded using either of two AOSLO modalities. Cross-sectional analysis was undertaken for seven patients and longitudinal analysis for one patient.

Results

Nine eyes from eight patients are presented in this case series. The mean age at the time of the assessment was 11.2 ± 6.5 years of age (range 7-29). A subfoveal continuous ellipsoid zone (EZ) line was present in eight eyes. Posterior pole AOSLO revealed patches of cone mosaics. Average cone densities at regions of interest 0.5° to the fovea ranged from 12,620 to 23,660 cells/mm2, whereas intercell spacing ranged from 7.0 to 9.7 µm.

Conclusions

This study demonstrates that AOSLO can provide useful high-quality images in patients with EOSRD, even during childhood, with nystagmus, and early macular atrophy. Cones at the posterior pole can appear as scattered islands or, possibly later in life, as a single subfoveal conglomerate. Detailed image analysis suggests that retinal pigment epithelial stress and dysfunction may be the initial step toward degeneration, with NIR being a useful tool to assess retinal well-being in RDH12-associated EOSRD.

Cell-cell interaction in the pathogenesis of inherited retinal diseases

The retina is part of the central nervous system specialized for vision. Inherited retinal diseases (IRD) are a group of clinically and genetically heterogenous disorders that lead to progressive vision impairment or blindness. Although each disorder is rare, IRD accumulatively cause blindness in up to 5.5 million individuals worldwide. Currently, the pathophysiological mechanisms of IRD are not fully understood and there are limited treatment options available. Most IRD are caused by degeneration of light-sensitive photoreceptors. Genetic mutations that abrogate the structure and/or function of photoreceptors lead to visual impairment followed by blindness caused by loss of photoreceptors. In healthy retina, photoreceptors structurally and functionally interact with retinal pigment epithelium (RPE) and Müller glia (MG) to maintain retinal homeostasis. Multiple IRD with photoreceptor degeneration as a major phenotype are caused by mutations of RPE- and/or MG-associated genes. Recent studies also reveal compromised MG and RPE caused by mutations in ubiquitously expressed ciliary genes. Therefore, photoreceptor degeneration could be a direct consequence of gene mutations and/or could be secondary to the dysfunction of their interaction partners in the retina. This review summarizes the mechanisms of photoreceptor-RPE/MG interaction in supporting retinal functions and discusses how the disruption of these processes could lead to photoreceptor degeneration, with an aim to provide a unique perspective of IRD pathogenesis and treatment paradigm. We will first describe the biology of retina and IRD and then discuss the interaction between photoreceptors and MG/RPE as well as their implications in disease pathogenesis. Finally, we will summarize the recent advances in IRD therapeutics targeting MG and/or RPE.

Visual function in children with Joubert syndrome

AIM

To describe visual function in children with Joubert syndrome and to investigate its possible association with diagnostic and developmental aspects.

METHOD

This retrospective cross-sectional work included 59 patients (33 male; mean age 9 years 2 months, standard deviation 6 years 3 months, range 4 months to 23 years) diagnosed with Joubert syndrome from January 2002 to December 2020. Data about clinical (neurological, neuro-ophthalmological, developmental/cognitive) and diagnostic (e.g. genetic testing, neuroimaging, systemic involvement) evaluations were collected in a data set during a review of medical records. Clinical and diagnostic variables were described in terms of raw counts and percentages. A χ2 test was conducted to investigate their association with neuropsychological skills.

RESULTS

Ocular motor apraxia was highly represented in our cohort (75%), with a high prevalence of refractive defects and retinal abnormalities. Developmental delay/intellectual disability was frequent (in 69.5% of the sample), associated with retinal dystrophy (p = 0.047) and reduced visual acuity both for near (p = 0.014) and for far distances (p = 0.017).

INTERPRETATION

On the basis of the relevance of oculomotor and perceptual alterations and their impact on overall and cognitive impairment, we encourage early and multidisciplinary assessment and follow-up of visual function in children with Joubert syndrome. This would help in planning a personalized rehabilitation to sustain functional vision. Further studies will be important to explore the link between biological aspects and global functioning in children with Joubert syndrome.

WHAT THIS PAPER ADDS

Perceptual deficits and oculomotor impairments frequently coexist in Joubert syndrome. Retinal dysfunction may be present despite the absence of funduscopic abnormalities. Both perceptual and oculomotor impairments negatively affect cognitive development in Joubert syndrome.

The Clinical Findings, Pathogenic Variants, and Gene Therapy Qualifications Found in a Leber Congenital Amaurosis Phenotypic Spectrum Patient Cohort

This retrospective study examines the clinical characteristics and underlying genetic variants that exist in a Leber congenital amaurosis (LCA) patient cohort evaluated at the inherited retinal disease (IRD) clinic at the University of Minnesota (UMN)/M Health System. Our LCA cohort consisted of 33 non-syndromic patients and one patient with Joubert syndrome. We report their relevant history, clinical findings, and genetic testing results. We monitored disease presentation utilizing ocular coherence tomography (OCT) and fundus autofluorescence (FAF). Electroretinogram testing (ERG) was performed in patients when clinically indicated. Next-generation sequencing (NGS) and genetic counseling was offered to all evaluated patients. Advanced photoreceptor loss was noted in 85.7% of the subjects. All patients who underwent FAF had findings of either a ring of macular hypo/hyper AF or peripheral hypo-AF. All patients had abnormal ERG findings. A diagnostic genetic test result was identified in 74.2% of the patients via NGS single-gene testing or panel testing. Two patients in our cohort qualified for Luxturna® and both received treatment at the time of this study. These data will help IRD specialists to understand the genetic variants and clinical presentations that characterize our patient population in the Midwest region of the United States.

Unlocking therapeutic potential: dual gene therapy for ameliorating the disease phenotypes in a mouse model of RPE65 Leber congenital amaurosis

Leber congenital amaurosis (LCA) is the most common genetic cause of congenital visual impairment in infants and children. Patients with LCA who harbor RPE65 mutations exhibit a deficiency in photoreceptor rhodopsin, leading to severe night blindness and visual impairment following birth. Since either gene replacement therapy or anti-apoptosis therapy alone cannot maintain both functional and morphological normality for a long time in the animal model, we propose a robust treatment strategy, that is, gene replacement therapy combined with anti-apoptotic therapy to protect photoreceptors from further degeneration while compensating for lost RPE65 function. Here, rd12 mice were injected subretinally at postnatal day 14 with four vector administrations, respectively. At 6 months after treatment, it was discovered that injection of three vectors, AAV8 (Y733F)-CBA-hRPE65, AAV8(Y733F)-CBA-hRPE65-BCL-2-L10 and mixture of half-dose AAV8(Y733F)-CBA-hRPE65 and half-dose AAV8 (Y733F)-CBA-BCL-2-L10, could partially restore the visual function of rd12 mice. Meanwhile, these treated eyes also exhibited a thicker outer nuclear layer (ONL) structure. However, despite the fact that the eyes of rd12 mice injected with the AAV8 (Y733F)-CBA-BCL-2-L10 vector displayed a slightly thicker ONL structure compared to untreated eyes, the visual function of the treated eyes did not recover. Continuing the observation period to 12 months after treatment, we found that compared to rd12 mice at 6-month post-treatment, rd12 mice injected with AAV8 (Y733F)-CBA-hRPE65 or mixture of half-dose AAV8(Y733F)-CBA-hRPE65 and half-dose AAV8 (Y733F)-CBA-BCL-2-L10 exhibited varying degrees of decline in both visual function and ONL thickness. However, in the case of rd12 mice injected with the AAV8(Y733F)-CBA-hRPE65-BCL-2-L10 vector, the ONL thickness remains consistent at both 6 and 12 months after treatment. These mice continued to maintain a relatively strong visual function and showed restoration in the levels of RPE65 and Rhodopsin protein expression. Our findings illustrate that early postnatal treatment with AAV vectors containing both the hRPE65 gene and the Bcl-2L10 anti-apoptotic gene provide enhanced and sustained retinal protection.

Full-field stimulus threshold testing: a scoping review of current practice

The full-field stimulus threshold (FST) is a psychophysical measure of whole-field retinal light sensitivity. It can assess residual visual function in patients with severe retinal disease and is increasingly being adopted as an endpoint in clinical trials. FST applications in routine ophthalmology clinics are also growing, but as yet there is no formalised standard guidance for measuring FST. This scoping review explored current variability in FST conduct and reporting, with an aim to inform further evidence synthesis and consensus guidance. A comprehensive electronic search and review of the literature was carried out according to the Preferred Reporting Items for Systematic Reviews and Meta-analysis Extension for Scoping Reviews (PRISMA-ScR) checklist. Key source, participant, methodology and outcomes data from 85 included sources were qualitatively and quantitatively compared and summarised. Data from 85 sources highlight how the variability and insufficient reporting of FST methodology, including parameters such as units of flash luminance, colour, duration, test strategy and dark adaptation, can hinder comparison and interpretation of clinical significance across centres. The review also highlights an unmet need for paediatric-specific considerations for test optimisation. Further evidence synthesis, empirical research or structured panel consultation may be required to establish coherent standardised guidance on FST methodology and context or condition dependent modifications. Consistent reporting of core elements, most crucially the flash luminance equivalence to 0 dB reference level is a first step. The development of criteria for quality assurance, calibration and age-appropriate reference data generation may further strengthen rigour of measurement.

Classification and Growth Rate of Chorioretinal Atrophy after Voretigene Neparvovec-Rzyl for RPE65-Mediated Retinal Degeneration

PURPOSE

Classify the appearance and quantify the growth rate of chorioretinal atrophy in patients who received voretigene neparvovec-rzyl (VN) for RPE65-mediated retinal degeneration.

DESIGN

Multicenter retrospective analysis.

SUBJECTS

Patients who underwent subretinal VN injection at 5 institutions and demonstrated posterior-pole chorioretinal atrophy.

METHODS

Ultrawidefield scanning laser ophthalmoscopy or color fundus photos were assessed before and after subretinal VN. Atrophy was defined as regions with ≥ 2 of the following: (1) partial or complete retinal pigment epithelial depigmentation; (2) round shape; (3) sharp margins; and (4) increased visibility of choroidal vessels. Atrophy was qualitatively classified into different subtypes. All atrophy was manually segmented. Linear mixed-effects models with random slopes and intercepts were fit using atrophy area and square root of atrophy area.

MAIN OUTCOME MEASURES

Number of eyes with each atrophy pattern, and slopes of linear mixed-effects models.

RESULTS

Twenty-seven eyes from 14 patients across 5 centers developed chorioretinal atrophy after subretinal VN. A mean of 5.8 ± 2.7 images per eye obtained over 2.2 ± 0.8 years were reviewed, and atrophy was categorized into touchdown (14 eyes), nummular (15 eyes), and perifoveal (12 eyes) subtypes. Fifteen eyes demonstrated > 1 type of atrophy. Thirteen of 14 patients demonstrated bilateral atrophy. The slopes of the mixed-effects models of atrophy area and square root of atrophy area (estimate ± standard error) were 1.7 ± 1.3 mm2/year and 0.6 ± 0.2 mm/year for touchdown atrophy, 5.5 ± 1.3 mm2/year and 1.2 ± 0.2 mm/year for nummular atrophy, and 16.7 ± 1.8 mm2/year and 2.3 ± 0.2 mm/year for perifoveal atrophy. The slopes for each type of atrophy were significantly different in the square root of atrophy model, which best fit the data (P < 0.05).

CONCLUSIONS

Chorioretinal atrophy after subretinal VN for RPE65-mediated retinal degeneration developed according to a touchdown, nummular, and/or perifoveal pattern. Perifoveal atrophy grew the most rapidly, while touchdown atrophy grew the least rapidly. Understanding the causes of these findings, which are present in a minority of patients, merits further investigation.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Intraflagellar transport: A critical player in photoreceptor development and the pathogenesis of retinal degenerative diseases

In vertebrate vision, photons are detected by highly specialized sensory cilia called outer segments. Photoreceptor outer segments form by remodeling the membrane of a primary cilium into a stack of flattened disks. Intraflagellar transport (IFT) is critical to the formation of most types of eukaryotic cilia including the outer segments. This review covers the state of knowledge of the role of IFT in the formation and maintenance of outer segments and the human diseases that result from mutations in genes encoding the IFT complex and associated motors.

A novel pathogenic CRB1 variant presenting as Leber Congenital Amaurosis 8 and evaluation of gene editing feasibility

INTRODUCTION

Leber Congenital Amaurosis (LCA) is an inherited retinal disease that presents in infancy with severely decreased vision, nystagmus, and extinguished electroretinography findings. LCA8 is linked to variants in the Crumbs homolog 1 (CRB1) gene.

CASE DESCRIPTION

We report a novel CRB1 variant in a 14-year-old male presenting with nystagmus, worsening vision, and inability to fixate on toys in his infancy. Color fundus photography revealed nummular pigments in the macula and periphery. Imaging studies revealed thickened retina on standard domain optical coherence tomography and widespread atrophy of the retinal pigment epithelium on autofluorescence. Full-field electroretinography revealed extinguished scotopic and significantly reduced photopic responses. Genetic testing demonstrated a novel homozygous variant, c.3057 T > A; p.(Tyr1019Ter), in the CRB1 gene. This variant is not currently amenable to base editing, however, in silico analysis revealed several potential prime editing strategies for correction.

CONCLUSION

This case presentation is consistent with LCA8, suggesting pathogenicity of this novel variant and expanding our knowledge of disease-causing CRB1 variants.

Durable vision improvement after a single intravitreal treatment with antisense oligonucleotide in CEP290-LCA: Replication in two eyes

Purpose

An intravitreally injected antisense oligonucleotide, sepofarsen, was designed to modulate splicing within retinas of patients with severe vision loss due to deep intronic c.2991 + 1655A > G variant in the CEP290 gene. A previous report showed vision improvements following a single injection in one eye with unexpected durability lasting at least 15 months. The current study evaluated durability of efficacy beyond 15 months in the previously treated left eye. In addition, peak efficacy and durability were evaluated in the treatment-naive right eye, and re-injection of the left eye 4 years after the first injection.

Observations

Visual function was evaluated with best corrected standard and low-luminance visual acuities, microperimetry, dark-adapted chromatic perimetry, and full-field sensitivity testing. Retinal structure was evaluated with OCT imaging. At the fovea, all visual function measures and IS/OS intensity of the OCT showed transient improvements peaking at 3-6 months, remaining better than baseline at ∼2 years, and returning to baseline by 3-4 years after each single injection.

Conclusions and Importance

These results suggest that sepofarsen reinjection intervals may need to be longer than 2 years.

Application of patient-derived induced pluripotent stem cells and organoids in inherited retinal diseases

Inherited retinal diseases (IRDs) can induce severe sight-threatening retinal degeneration and impose a considerable economic burden on patients and society, making efforts to cure blindness imperative. Transgenic animals mimicking human genetic diseases have long been used as a primary research tool to decipher the underlying pathogenesis, but there are still some obvious limitations. As an alternative strategy, patient-derived induced pluripotent stem cells (iPSCs), particularly three-dimensional (3D) organoid technology, are considered a promising platform for modeling different forms of IRDs, including retinitis pigmentosa, Leber congenital amaurosis, X-linked recessive retinoschisis, Batten disease, achromatopsia, and best vitelliform macular dystrophy. Here, this paper focuses on the status of patient-derived iPSCs and organoids in IRDs in recent years concerning disease modeling and therapeutic exploration, along with potential challenges for translating laboratory research to clinical application. Finally, the importance of human iPSCs and organoids in combination with emerging technologies such as multi-omics integration analysis, 3D bioprinting, or microfluidic chip platform are highlighted. Patient-derived retinal organoids may be a preferred choice for more accurately uncovering the mechanisms of human retinal diseases and will contribute to clinical practice.

Preliminary characterization of a novel form of progressive retinal atrophy in the German Spitz dog associated with a frameshift mutation in GUCY2D

OBJECTIVE

To describe the clinical, preliminary electroretinographic and optical coherence tomography features of a newly identified form of progressive retinal atrophy (PRA) in German Spitzes, and identify the causal gene mutation.

ANIMALS

Thirty-three client-owned German Spitz dogs were included.

PROCEDURES

All animals underwent a full ophthalmic examination, including vision testing. In addition, fundus photography, ERG, and OCT were performed. A DNA-marker-based association analysis was performed to screen potential candidate genes and the whole genomes of four animals were sequenced.

RESULTS

Initial fundus changes were pale papilla and mild vascular attenuation. Oscillatory nystagmus was noted in 14 of 16 clinically affected puppies. Vision was impaired under both scotopic and photopic conditions. Rod-mediated ERGs were unrecordable in all affected dogs tested, reduced cone-mediated responses were present in one animal at 3 months of age and unrecordable in the other affected animals tested. Multiple small retinal bullae were observed in three clinically affected animals (two with confirmed genetic diagnosis). OCT showed that despite loss of function, retinal structure was initially well-preserved, although a slight retinal thinning developed in older animals with the ventral retina being more severely affected. Pedigree analysis supported an autosomal recessive inheritance. A mutation was identified in GUCY2D, which segregated with the disease (NM_001003207.1:c.1598_1599insT; p.(Ser534GlufsTer20)). Human subjects with GUCY2D mutations typically show an initial disconnect between loss of function and loss of structure, a feature recapitulated in the affected dogs in this study.

CONCLUSION

We identified early-onset PRA in the German Spitz associated with a frameshift mutation in GUCY2D.

The New Era of Therapeutic Strategies for the Treatment of Retinitis Pigmentosa: A Narrative Review of Pathomolecular Mechanisms for the Development of Cell-Based Therapies

Retinitis pigmentosa, defined more properly as cone-rod dystrophy, is a paradigm of inherited diffuse retinal dystrophies, one of the rare diseases with the highest prevalence in the worldwide population and one of the main causes of low vision in the pediatric and elderly age groups. Advancements in and the understanding of molecular biology and gene-editing technologies have raised interest in laying the foundation for new therapeutic strategies for rare diseases. As a consequence, new possibilities for clinicians and patients are arising due to the feasibility of treating such a devastating disorder, reducing its complications. The scope of this review focuses on the pathomolecular mechanisms underlying RP better to understand the prospects of its treatment using innovative approaches.

Occult Macular Dysfunction Syndrome: Identification of Multiple Pathologies in a Clinical Spectrum of Macular Dysfunction with Normal Fundus in East Asian Patients: EAOMD Report No. 5

Occult macular dystrophy (OMD) is the most prevalent form of macular dystrophy in East Asia. Beyond RP1L1, causative genes and mechanisms remain largely uncharacterised. This study aimed to delineate the clinical and genetic characteristics of OMD syndrome (OMDS). Patients clinically diagnosed with OMDS in Japan, South Korea, and China were enrolled. The inclusion criteria were as follows: (1) macular dysfunction and (2) normal fundus appearance. Comprehensive clinical evaluation and genetic assessment were performed to identify the disease-causing variants. Clinical parameters were compared among the genotype groups. Seventy-two patients with OMDS from fifty families were included. The causative genes were RP1L1 in forty-seven patients from thirty families (30/50, 60.0%), CRX in two patients from one family (1/50, 2.0%), GUCY2D in two patients from two families (2/50, 4.0%), and no genes were identified in twenty-one patients from seventeen families (17/50, 34.0%). Different severities were observed in terms of disease onset and the prognosis of visual acuity reduction. This multicentre large cohort study furthers our understanding of the phenotypic and genotypic spectra of patients with macular dystrophy and normal fundus. Evidently, OMDS encompasses multiple Mendelian retinal disorders, each representing unique pathologies that dictate their respective severity and prognostic patterns.

Gene Therapy in Hereditary Retinal Dystrophies: The Usefulness of Diagnostic Tools in Candidate Patient Selections

PURPOSE

Gene therapy actually seems to have promising results in the treatment of Leber Congenital Amaurosis and some different inherited retinal diseases (IRDs); the primary goal of this strategy is to change gene defects with a wild-type gene without defects in a DNA sequence to achieve partial recovery of the photoreceptor function and, consequently, partially restore lost retinal functions. This approach led to the introduction of a new drug (voretigene neparvovec-rzyl) for replacement of the RPE65 gene in patients affected by Leber Congenital Amaurosis (LCA); however, the treatment results are inconstant and with variable long-lasting effects due to a lack of correctly evaluating the anatomical and functional conditions of residual photoreceptors. These variabilities may also be related to host immunoreactive reactions towards the Adenovirus-associated vector. A broad spectrum of retinal dystrophies frequently generates doubt as to whether the disease or the patient is a good candidate for a successful gene treatment, because, very often, different diseases share similar genetic characteristics, causing an inconstant genotype/phenotype correlation between clinical characteristics also within the same family. For example, mutations on the RPE65 gene cause Leber Congenital Amaurosis (LCA) but also some forms of Retinitis Pigmentosa (RP), Bardet Biedl Syndrome (BBS), Congenital Stationary Night Blindness (CSNB) and Usher syndrome (USH), with a very wide spectrum of clinical manifestations. These confusing elements are due to the different pathways in which the product protein (retinoid isomer-hydrolase) is involved and, consequently, the overlapping metabolism in retinal function. Considering this point and the cost of the drug (over USD one hundred thousand), it would be mandatory to follow guidelines or algorithms to assess the best-fitting disease and candidate patients to maximize the output. Unfortunately, at the moment, there are no suggestions regarding who to treat with gene therapy. Moreover, gene therapy might be helpful in other forms of inherited retinal dystrophies, with more frequent incidence of the disease and better functional conditions (actually, gene therapy is proposed only for patients with poor vision, considering possible side effects due to the treatment procedures), in which this approach leads to better function and, hopefully, visual restoration. But, in this view, who might be a disease candidate or patient to undergo gene therapy, in relationship to the onset of clinical trials for several different forms of IRD? Further, what is the gold standard for tests able to correctly select the patient? Our work aims to evaluate clinical considerations on instrumental morphofunctional tests to assess candidate subjects for treatment and correlate them with clinical and genetic defect analysis that, often, is not correspondent. We try to define which parameters are an essential and indispensable part of the clinical rationale to select patients with IRDs for gene therapy. This review will describe a series of models used to characterize retinal morphology and function from tests, such as optical coherence tomography (OCT) and electrophysiological evaluation (ERG), and its evaluation as a primary outcome in clinical trials. A secondary aim is to propose an ancillary clinical classification of IRDs and their accessibility based on gene therapy's current state of the art.

MATERIAL AND METHODS

OCT, ERG, and visual field examinations were performed in different forms of IRDs, classified based on clinical and retinal conditions; compared to the gene defect classification, we utilized a diagnostic algorithm for the clinical classification based on morphofunctional information of the retina of patients, which could significantly improve diagnostic accuracy and, consequently, help the ophthalmologist to make a correct diagnosis to achieve optimal clinical results. These considerations are very helpful in selecting IRD patients who might respond to gene therapy with possible therapeutic success and filter out those in which treatment has a lower chance or no chance of positive results due to bad retinal conditions, avoiding time-consuming patient management with unsatisfactory results.

The Structural Abnormalities Are Deeply Involved in the Cause of RPGRIP1-Related Retinal Dystrophy in Japanese Patients

Leber congenital amaurosis (LCA) is the most severe form of inherited retinal dystrophy. RPGRIP1-related LCA accounts for 5-6% of LCA. We performed whole-exome sequencing and whole-genome sequencing (WGS) on 29 patients with clinically suspected LCA and examined ophthalmic findings in patients with biallelic pathogenic variants of RPGRIP1. In addition to five previously reported cases, we identified five cases from four families with compound heterozygous RPGRIP1 variants using WGS. Five patients had null variants comprising frameshift variants, an Alu insertion, and microdeletions. A previously reported 1339 bp deletion involving exon 18 was found in four cases, and the deletion was relatively prevalent in the Japanese population (allele frequency: 0.002). Microdeletions involving exon 1 were detected in four cases. In patients with RPGRIP1 variants, visual acuity remained low, ranging from light perception to 0.2, and showed no correlation with age. In optical coherence tomography images, the ellipsoid zone (EZ) length decreased with age in all but one case of unimpaired EZ. The retinal structure was relatively preserved in all cases; however, there were cases with great differences in visual function compared to their siblings and a 56-year-old patient who still had a faint EZ line. Structural abnormalities may be important genetic causes of RPGRIP1-related retinal dystrophy in Japanese patients, and WGS was useful for detecting them.

Exome sequencing in retinal dystrophy patients reveals a novel candidate gene ER membrane protein complex subunit 3

Inherited retinal dystrophies (IRDs) are a heterogeneous group of visual disorders caused by different pathogenic mutations in genes and regulatory sequences. The endoplasmic reticulum (ER) membrane protein complex (EMC) subunit 3 (EMC3) is the core unit of the EMC insertase that integrates the transmembrane peptides into lipid bilayers, and the function of its cytoplasmic carboxyl terminus remains to be elucidated. In this study, an insertional mutation c.768insT in the C-terminal coding region of EMC3 was identified and associated with dominant IRDs in a five-generation family. This mutation caused a frameshift in the coding sequence and a gain of an additional 16 amino acid residues (p.L256F-fs-ext21) to form a helix structure in the C-terminus of the EMC3 protein. The mutation is heterozygous with an incomplete penetrance, and cosegregates in all patients examined. This finding indicates that the C-terminus of EMC3 is essential for EMC functions and that EMC3 may be a novel candidate gene for retinal degenerative diseases.

Reduced ADP off-rate by the yeast CCT2 double mutation T394P/R510H which causes Leber congenital amaurosis in humans

The CCT/TRiC chaperonin is found in the cytosol of all eukaryotic cells and assists protein folding in an ATP-dependent manner. The heterozygous double mutation T400P and R516H in subunit CCT2 is known to cause Leber congenital amaurosis (LCA), a hereditary congenital retinopathy. This double mutation also renders the function of subunit CCT2, when it is outside of the CCT/TRiC complex, to be defective in promoting autophagy. Here, we show using steady-state and transient kinetic analysis that the corresponding double mutation in subunit CCT2 from Saccharomyces cerevisiae reduces the off-rate of ADP during ATP hydrolysis by CCT/TRiC. We also report that the ATPase activity of CCT/TRiC is stimulated by a non-folded substrate. Our results suggest that the closed state of CCT/TRiC is stabilized by the double mutation owing to the slower off-rate of ADP, thereby impeding the exit of CCT2 from the complex that is required for its function in autophagy.

A health terminological system for inherited retinal diseases: Content coverage evaluation and a proposed classification

PURPOSE

To present a classification of inherited retinal diseases (IRDs) and evaluate its content coverage in comparison with common standard terminology systems.

METHODS

In this comparative cross-sectional study, a panel of subject matter experts annotated a list of IRDs based on a comprehensive review of the literature. Then, they leveraged clinical terminologies from various reference sets including Unified Medical Language System (UMLS), Online Mendelian Inheritance in Man (OMIM), International Classification of Diseases (ICD-11), Systematized Nomenclature of Medicine (SNOMED-CT) and Orphanet Rare Disease Ontology (ORDO).

RESULTS

Initially, we generated a hierarchical classification of 62 IRD diagnosis concepts in six categories. Subsequently, the classification was extended to 164 IRD diagnoses after adding concepts from various standard terminologies. Finally, 158 concepts were selected to be classified into six categories and genetic subtypes of 412 cases were added to the related concepts. UMLS has the greatest content coverage of 90.51% followed respectively by SNOMED-CT (83.54%), ORDO (81.01%), OMIM (60.76%), and ICD-11 (60.13%). There were 53 IRD concepts (33.54%) that were covered by all five investigated systems. However, 2.53% of the IRD concepts in our classification were not covered by any of the standard terminologies.

CONCLUSIONS

This comprehensive classification system was established to organize IRD diseases based on phenotypic and genotypic specifications. It could potentially be used for IRD clinical documentation purposes and could also be considered a preliminary step forward to developing a more robust standard ontology for IRDs or updating available standard terminologies. In comparison, the greatest content coverage of our proposed classification was related to the UMLS Metathesaurus.

[Gene therapy in ophthalmology]

In 2017 the gene therapy medication voretigene neparvovec-rzyl was approved by the U.S. Food and Drug Administration (FDA) for retinal gene therapy of hereditary retinal dystrophies caused by mutations in the RPE65 gene. Voretigene neparvovec-rzyl is a gene augmentation therapy using an  adeno-associated virus-based vector to express a healthy copy of the human RPE65 gene in the patient's retinal pigment epithelial (RPE) cells. The success of gene augmentation therapy in RPE65-linked retinal dystrophy encouraged research activities on the concept of gene supplementation to be extended to nongenetic diseases, such as age-related macular degeneration; however, it also showed that the principle of success cannot be easily extended to other retinal dystrophies. This review article presents the most commonly used principles and technologies of gene therapy and provides an overview of the current challenges and limitations. Furthermore, practice-relevant aspects of the indications and the treatment procedure are discussed. Particular attention is paid to the consideration of disease stages, especially with respect to patient's expectations and the evaluation of treatment success.

Genome editing in the treatment of ocular diseases

Genome-editing technologies have ushered in a new era in gene therapy, providing novel therapeutic strategies for a wide range of diseases, including both genetic and nongenetic ocular diseases. These technologies offer new hope for patients suffering from previously untreatable conditions. The unique anatomical and physiological features of the eye, including its immune-privileged status, size, and compartmentalized structure, provide an optimal environment for the application of these cutting-edge technologies. Moreover, the development of various delivery methods has facilitated the efficient and targeted administration of genome engineering tools designed to correct specific ocular tissues. Additionally, advancements in noninvasive ocular imaging techniques and electroretinography have enabled real-time monitoring of therapeutic efficacy and safety. Herein, we discuss the discovery and development of genome-editing technologies, their application to ocular diseases from the anterior segment to the posterior segment, current limitations encountered in translating these technologies into clinical practice, and ongoing research endeavors aimed at overcoming these challenges.

A multidisciplinary approach to inherited retinal dystrophies from diagnosis to initial care: a narrative review with inputs from clinical practice

BACKGROUND

Non-syndromic inherited retinal dystrophies (IRDs) such as retinitis pigmentosa or Leber congenital amaurosis generally manifest between early childhood and late adolescence, imposing profound long-term impacts as a result of vision impairment or blindness. IRDs are highly heterogeneous, with often overlapping symptoms among different IRDs, and achieving a definite diagnosis is challenging. This narrative review provides a clinical overview of the non-syndromic generalized photoreceptor dystrophies, particularly retinitis pigmentosa and Leber congenital amaurosis. The clinical investigations and genetic testing needed to establish a diagnosis are outlined, and current management approaches are discussed, focusing on the importance of the involvement of an interdisciplinary team from diagnosis and initial care to long-term follow-up and support.

RESULTS

The effective management of IRDs requires a multidisciplinary, and ideally interdisciplinary, team of experts knowledgeable about IRDs, with experienced professionals from fields as diverse as ophthalmology, neuropsychiatry, psychology, neurology, genetics, orthoptics, developmental therapy, typhlology, occupational therapy, otolaryngology, and orientation and mobility specialties. Accurate clinical diagnosis encompasses a range of objective and subjective assessments as a prerequisite for the genetic testing essential in establishing an accurate diagnosis necessary for the effective management of IRDs, particularly in the era of gene therapies. Improvements in genome sequencing techniques, such as next-generation sequencing, have greatly facilitated the complex process of determining IRD-causing gene variants and establishing a molecular diagnosis. Genetic counseling is essential to help the individual and their family understand the condition, the potential risk for offspring, and the implications of a diagnosis on visual prognosis and treatment options. Psychological support for patients and caregivers is important at all stages of diagnosis, care, and rehabilitation and is an essential part of the multidisciplinary approach to managing IRDs. Effective communication throughout is essential, and the patient and caregivers' needs and expectations must be acknowledged and discussed.

CONCLUSION

As IRDs can present at an early age, clinicians need to be aware of the clinical signs suggesting visual impairment and follow up with multidisciplinary support for timely diagnoses to facilitate appropriate therapeutic or rehabilitation intervention to minimize vision loss.

Nationwide genetic analysis of more than 600 families with inherited eye diseases in Argentina

This study corresponds to the first large-scale genetic analysis of inherited eye diseases (IED) in Argentina and describes the comprehensive genetic profile of a large cohort of patients. Medical records of 22 ophthalmology and genetics services throughout 13 Argentinian provinces were analyzed retrospectively. Patients with a clinical diagnosis of an ophthalmic genetic disease and a history of genetic testing were included. Medical, ophthalmological and family history was collected. A total of 773 patients from 637 families were included, with 98% having inherited retinal disease. The most common phenotype was retinitis pigmentosa (RP, 62%). Causative variants were detected in 379 (59%) patients. USH2A, RPGR, and ABCA4 were the most common disease-associated genes. USH2A was the most frequent gene associated with RP, RDH12 early-onset severe retinal dystrophy, ABCA4 Stargardt disease, PROM1 cone-rod dystrophy, and BEST1 macular dystrophy. The most frequent variants were RPGR c.1345 C > T, p.(Arg449*) and USH2A c.15089 C > A, p.(Ser5030*). The study revealed 156/448 (35%) previously unreported pathogenic/likely pathogenic variants and 8 possible founder mutations. We present the genetic landscape of IED in Argentina and the largest cohort in South America. This data will serve as a reference for future genetic studies, aid diagnosis, inform counseling, and assist in addressing the largely unmet need for clinical trials to be conducted in the region.

Genetic and Clinical Profile of Retinopathies Due to Disease-Causing Variants in Leber Congenital Amaurosis (LCA)-Associated Genes in a Large German Cohort

To report the spectrum of Leber congenital amaurosis (LCA) associated genes in a large German cohort and to delineate their associated phenotype. Local databases were screened for patients with a clinical diagnosis of LCA and for patients with disease-causing variants in known LCA-associated genes independent of their clinical diagnosis. Patients with a mere clinical diagnosis were invited for genetic testing. Genomic DNA was either analyzed in a diagnostic-genetic or research setup using various capture panels for syndromic and non-syndromic IRD (inherited retinal dystrophy) genes. Clinical data was obtained mainly retrospectively. Patients with genetic and phenotypic information were eventually included. Descriptive statistical data analysis was performed. A total of 105 patients (53 female, 52 male, age 3-76 years at the time of data collection) with disease-causing variants in 16 LCA-associated genes were included. The genetic spectrum displayed variants in the following genes: CEP290 (21%), CRB1 (21%), RPE65 (14%), RDH12 (13%), AIPL1 (6%), TULP1 (6%), and IQCB1 (5%), and few cases harbored pathogenic variants in LRAT, CABP4, NMNAT1, RPGRIP1, SPATA7, CRX, IFT140, LCA5, and RD3 (altogether accounting for 14%). The most common clinical diagnosis was LCA (53%, 56/105) followed by retinitis pigmentosa (RP, 40%, 42/105), but also other IRDs were seen (cone-rod dystrophy, 5%; congenital stationary night blindness, 2%). Among LCA patients, 50% were caused by variants in CEP290 (29%) and RPE65 (21%), whereas variants in other genes were much less frequent (CRB1 11%, AIPL1 11%, IQCB1 9%, and RDH12 7%, and sporadically LRAT, NMNAT1, CRX, RD3, and RPGRIP1). In general, the patients showed a severe phenotype hallmarked by severely reduced visual acuity, concentric narrowing of the visual field, and extinguished electroretinograms. However, there were also exceptional cases with best corrected visual acuity as high as 0.8 (Snellen), well-preserved visual fields, and preserved photoreceptors in spectral domain optical coherence tomography. Phenotypic variability was seen between and within genetic subgroups. The study we are presenting pertains to a considerable LCA group, furnishing valuable comprehension of the genetic and phenotypic spectrum. This knowledge holds significance for impending gene therapeutic trials. In this German cohort, CEP290 and CRB1 are the most frequently mutated genes. However, LCA is genetically highly heterogeneous and exhibits clinical variability, showing overlap with other IRDs. For any therapeutic gene intervention, the disease-causing genotype is the primary criterion for treatment access, but the clinical diagnosis, state of the retina, number of to be treated target cells, and the time point of treatment will be crucial.

Genetic causes of inherited retinal diseases among Israeli Jews of Ethiopian ancestry

Purpose

This study sought to describe the phenotype frequency and genetic basis of inherited retinal diseases (IRDs) among a nationwide cohort of Israeli Jewish patients of Ethiopian ancestry.

Methods

Patients' data-including demographic, clinical, and genetic information-were obtained through members of the Israeli Inherited Retinal Disease Consortium (IIRDC). Genetic analysis was performed by either Sanger sequencing for founder mutations or next-generation sequencing (targeted next-generation sequencing or whole-exome sequencing).

Results

Forty-two patients (58% female) from 36 families were included, and their ages ranged from one year to 82 years. Their most common phenotypes were Stargardt disease (36%) and nonsyndromic retinitis pigmentosa (33%), while their most common mode of inheritance was autosomal recessive inheritance. Genetic diagnoses were ascertained for 72% of genetically analyzed patients. The most frequent gene involved was ABCA4. Overall, 16 distinct IRD mutations were identified, nine of which are novel. One of them, ABCA4-c.6077delT, is likely a founder mutation among the studied population.

Conclusions

This study is the first to describe IRDs' phenotypic and molecular characteristics in the Ethiopian Jewish community. Most of the identified variants are rare. Our findings can help caregivers with clinical and molecular diagnosis and, we hope, enable adequate therapy in the near future.

Voretigene Neparvovec for the Treatment of RPE65-associated Retinal Dystrophy: Consensus and Recommendations from the Korea RPE65-IRD Consensus Paper Committee

Mutations in the RPE65 gene, associated with Leber congenital amaurosis, early-onset severe retinal dystrophy, and retinitis pigmentosa, gained growing attention since gene therapy for patients with RPE65-associated retinal dystrophy is available in clinical practice. RPE65 gene accounts for a very small proportion of patients with inherited retinal degeneration, especially Asian patients. Because RPE65-associated retinal dystrophy shares common clinical characteristics, such as early-onset severe nyctalopia, nystagmus, low vision, and progressive visual field constriction, with retinitis pigmentosa by other genetic mutations, appropriate genetic testing is essential to make a correct diagnosis. Also, fundus abnormalities can be minimal in early childhood, and the phenotype is highly variable depending on the type of mutations in RPE65-associated retinal dystrophy, which makes a diagnostic difficulty. The aim of this paper is to review the epidemiology of RPE65-associated retinal dystrophy, mutation spectrum, genetic diagnosis, clinical characteristics, and voretigene neparvovec, a gene therapy product for the treatment of RPE65-related retinal dystrophy.

Novel CRB1 pathogenic variant in Chuuk families with Leber congenital amaurosis

The purpose of this article is to determine the cause of Leber congenital amaurosis (LCA) in Chuuk state, Federated States of Micronesia (FSM). In this prospective observational case series, five patients with early-onset vision loss were examined in Chuuk state, FSM, during an ocular genetics visit to study the elevated incidence of microphthalmia. Because of their low vision these patients were incorrectly assumed to have microphthalmia. A complete ophthalmological exam established a clinical diagnosis of LCA. Candidate gene exons were sequenced with a targeted retinal dystrophy panel. Five subjects in three related families were diagnosed with LCA. All five were from Tonoas Island, within the Chuuk Lagoon, with ages ranging from 6 months to 16 years. DNA sequencing of affected individuals revealed a homozygous CRB1 NM_201253.3:c.3134del pathogenic variant, which was heterozygous in their parents. CRB1 genotypes were confirmed by a PCR restriction assay. We report identification of a founder pathogenic variant in CRB1 responsible for autosomal recessive LCA in this isolated community. This discovery will lead to appropriate recurrence risk counseling.

Clinical and Molecular Features of a Chinese Cohort With Syndromic and Nonsyndromic Retinal Dystrophies Related to the CEP290 Gene

PURPOSE

To reveal the clinical and genetic features of 54 Chinese pedigrees with syndromic or nonsyndromic retinal dystrophies related to CEP290 and to explore the genotype-phenotype correlation.

DESIGN

Retrospective cohort study.

METHODS

Patients diagnosed with nonsyndromic inherited retinal dystrophy (IRD) or syndromic ciliopathy (SCP) were enrolled. We identified 61 patients from 54 families carrying biallelic pathogenic CEP290 variants using next-generation sequencing, Sanger sequencing, and co-segregation validation. Genotype-phenotype correlation was evaluated.

RESULTS

This study included 37 IRD patients from 32 families and 24 patients with SCP from 22 pedigrees. Four retinal dystrophy phenotypes were confirmed: Leber congenital amaurosis (LCA, 46/61), early-onset severe retinal dystrophy (EOSRD, 4/61), retinitis pigmentosa (RP, 10/61), and cone-rod dystrophy (CORD, 1/61). The SCP phenotypes included Joubert syndrome (JS) (23/24) and Bardet-Biedl syndrome (BBS) (1/24). We detected 73 different CEP290 variants, of which 33 (45.2%) were not previously reported. Two novel copy number variations (CNVs) and 1 novel pathogenic synonymous change were identified. The most recurrent alterations in the IRD and SCP were p.Q123* (6/64, 9.4%) and p.I556Ffs*17 (10/44, 22.7%), respectively. IRD patients carried more stop-gain alleles (25/64, 39.1%), whereas SCP patients carried more frameshift alleles (23/44, 52.3%).

CONCLUSIONS

LCA was the most common retinal dystrophy phenotype, and JS was the most prevalent syndrome in CEP290 patients; RP/CORD and BBS may be present in early adulthood. The hot spot variants and distribution of genotypes were distinct between IRD and SCP. Our study expands the CEP290 variant spectrum and enhances the current knowledge of CEP290 heterogeneity.