The Impact of Inherited Retinal Diseases in the Republic of Ireland (ROI) and the United Kingdom (UK) from a Cost-of-Illness Perspective

Impacts of X-linked Retinitis Pigmentosa and Patient Pathways in European Countries: Results from the Cross-sectional EXPLORE XLRP-1 Physician Survey

INTRODUCTION

X-linked retinitis pigmentosa (XLRP) is a rare, incurable, vision-threatening, genetic disease. In this study, we aimed to reveal the real-world burden of this disease from the viewpoint of retina specialists and geneticists involved directly in XLRP care and to identify unique insights that may not otherwise be available through typical clinical studies or health economic research.

METHODS

In this exploratory, cross-sectional study (EXPLORE XLRP-1), retina specialists (n = 20) and geneticists (n = 5) in France, Germany, Italy, Spain, and the UK provided anonymized insights on their experiences managing patients with XLRP (n = 80) via an online survey and 60-min telephone interview.

RESULTS

Survey respondents reported that patient independence decreased over time, where 37% of patients were considered "completely autonomous" at diagnosis versus 23% at the last consultation. At their last visit, 45% of patients were active in the workforce; 67% (12/18) of "completely autonomous" patients had active working status compared with 13% (1/8) of "completely dependent" patients. The average time from onset of symptoms to diagnosis was 4 years and varied among countries. In 78% of patients, XLRP was confirmed by genetic testing, the rate of which varied among countries (range, 50-94%), taking up to 6 months to receive results. Specialists identified unmet needs in XLRP management including more standardized assessments of quality of life (QoL) as well as easier and earlier access to specialists, genetic testing, patient support programs, and effective treatment options.

CONCLUSIONS

The diagnosis, genetic testing, and management pathways among patients with XLRP can vary considerably. There is a need for more standardized diagnosis and management pathways, and QoL assessments, due to the major impact that XLRP has on patients' lives.

Investigating retinal explant models cultured in static and perfused systems to test the performance of exosomes secreted from retinal organoids

BACKGROUND

Ex vivo cultures of retinal explants are appropriate models for translational research. However, one of the difficult problems of retinal explants ex vivo culture is that their nutrient supply needs cannot be constantly met.

NEW METHOD

This study evaluated the effect of perfused culture on the survival of retinal explants, addressing the challenge of insufficient nutrition in static culture. Furthermore, exosomes secreted from retinal organoids (RO-Exos) were stained with PKH26 to track their uptake in retinal explants to mimic the efficacy of exosomal drugs in vivo.

RESULTS

We found that the retinal explants cultured with perfusion exhibited significantly higher viability, increased NeuN+ cells, and reduced apoptosis compared to the static culture group at Days Ex Vivo (DEV) 4, 7, and 14. The perfusion-cultured retinal explants exhibited reduced mRNA markers for gliosis and microglial activation, along with lower expression of GFAP and Iba1, as revealed by immunostaining. Additionally, RNA-sequencing analysis showed that perfusion culture mainly upregulated genes associated with visual perception and photoreceptor cell maintenance while downregulating the immune system process and immune response. RO-Exos promoted the uptake of PKH26-labelled exosomes and the growth of retinal explants in perfusion culture.

COMPARISON WITH EXISTING METHODS

Our perfusion culture system can provide a continuous supply of culture medium to achieve steady-state equilibrium in retinal explant culture. Compared to traditional static culture, it better preserves the vitality, provides better neuroprotection, and reduces glial activation.

CONCLUSIONS

This study provides a promising ex vivo model for further studies on degenerative retinal diseases and drug screening.

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.

Leber hereditary optic neuropathy in Czechia and Slovakia: Quality of life and costs from patient perspective

Introduction

Leber hereditary optic neuropathy (LHON) is the most frequent mitochondrial disease causing dyschromatopsia and progressive central visual loss that is subacute in progression and painless. Several studies have been published assessing QoL in patients with LHON, but no estimate of the economic burden has been reported to date. This study aims to quantify direct non-medical and indirect costs (productivity loss) incurred by LHON patients and their informal caregivers in Czechia and Slovakia, as well as to assess their quality of life.

Methods

The study was performed in 27 adults and children with LHON. To determine the socioeconomic burden of LHON, separate questionnaires for adults, children, and their parents were developed, including demographic and socioeconomic data. The following data were collected: age, education, family size, severity of LHON, non-medical direct and indirect costs of LHON.

Results

The mean age of adult respondents was 36.1 years (SD 13.1; n = 21). The total cost of absenteeism was EUR 1003 per person/year in adult employees, and EUR 2711 per person/year in children's parents. The productivity loss as a consequence of LHON due to combined relative absenteeism and relative presenteeism was estimated at EUR 9840 per an adult patient/year, and EUR 6298 per a parent/year, respectively. The mean cost of informal care was estimated at EUR 4502 (SD 4772; n = 6) per person/year. The mean VFQ-25 score for adult patients with LHON was 43.47 (SD 15.86).

Conclusion

The results of this study clearly show that patients with LHON and their families face an extensive socioeconomic burden related to this rare disease. Early, timely and appropriate access to diagnosis, treatment, and reimbursement decisions, but also to psychological counselling and services may help the patients and their relatives adapt and cope with the challenging aspects of vision loss and life with the disease.

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.

The Visual Impairment of Inherited Retinal Diseases in Portugal as per the National Table of Disabilities

Purpose

To evaluate the visual impairment of patients with inherited retinal diseases (IRDs), as per the national table of disabilities (TNI).

Design

Retrospective, single-center cohort study.

Participants

Patients with a clinical diagnosis of IRD were recruited at a referral center in Portugal.

Methods

Demographics and clinical data were collected from each individual patient file. The estimated visual disability coefficient was calculated through the evaluation of 7 graduated categories: orbital or eyelid deformities, low vision, visual field change, loss of bi-foveolar fixation, oculomotor palsy, photophobia, and chronic conjunctivitis. The TNI provides minimum and maximum disability values for numerous conditions within each category, which were summed to calculate an overall summary disability coefficient for each patient.

Main Outcome Measures

Demographic/clinical and estimated minimum and maximum visual disability coefficient according to the TNI for each patient.

Results

This study included 253 patients from 214 families, aged 3 to 80 years, with a mean age of 39.8 ± 20.0 years. The mean estimated minimum and maximum visual disability coefficients as per the TNI were 0.6 ± 0.4 and 0.7 ± 0.4, respectively. The low vision was the single most frequent contributor category (21.7%) present in the calculation of visual impairment. Low vision and visual field changes were the most frequent double combination (18.2%), and the addition of loss of bi-foveolar fixation was the most frequent triple combination (8.3%).

Conclusions

This study found that IRD patients had a significant visual disability, with the majority having a disability coefficient ≥0.6, which would qualify them for a "multipurpose disability medical certificate."

Financial Disclosures

The authors have no proprietary or commercial interest in any materials discussed in this article.

The socioeconomic epidemiology of inherited retinal diseases in Portugal

BACKGROUND

Inherited retinal diseases (IRDs) are a group of rare degenerative disorders of the retina that can lead to blindness from birth to late middle age. Knowing the target population and its resources is essential to better plan support measures. The aim of this study was to evaluate the socioeconomic characteristics of regions in Portugal where IRD patients reside to inform the planning of vision aid and rehabilitation intervention measures.

RESULTS

This study included 1082 patients from 973 families, aged 3 to 92 years, with a mean age of 44.8 ± 18.1 years. Patients living with an IRD were identified in 190 of the 308 municipalities. According to this study, the estimated IRD prevalence in Portugal was 10.4 per 100,000 inhabitants, and by municipalities, it ranged from 0 to 131.2 per 100,000 inhabitants. Overall, regions with a higher prevalence of IRD have a lower population density (r=-0.371, p < 0.001), a higher illiteracy rate (r = 0.404, p < 0.001) and an overall older population (r = 0.475, p < 0.001). Additionally, there is a lower proportion of doctor per capita (r = 0.350, p < 0.001), higher social security pensions beneficiaries (r = 0.439, p < 0.001), worse water quality for human consumption (r=-0.194, p = 0.008), fewer audiences at the cinema (r=-0.315, p < 0.001) and lower proportion of foreign guests in tourist accommodations (r=-0.287, p < 0.001).

CONCLUSION

The number of identified patients with IRD varied between regions. Using data from national statistics (PORDATA), we observed differences in socioeconomic characteristics between regions. Multiple targeted aid strategies can be developed to ensure that all IRD patients are granted full clinical and socioeconomic support.

Whole genome sequencing for inherited retinal diseases in the Korean National Project of Bio Big Data

PURPOSE

This study aimed to analyze the genetic results of inherited retinal diseases (IRDs) and evaluate the diagnostic usefulness of whole genome sequencing (WGS) in the Korean National Project of Bio Big Data.

METHODS

As part of the Korean National Project of Bio Big Data, WGS was performed on 32 individuals with IRDs with no identified pathogenic variants through whole or targeted exome sequencing.

RESULTS

Individuals with retinitis pigmentosa (n = 23), cone dystrophy (n = 2), cone-rod dystrophy (n = 2), familial exudative vitreoretinopathy (n = 2), pigmented paravenous chorioretinal atrophy (n = 1), North Carolina macular dystrophy (n = 1), and bull's-eye macular dystrophy (n = 1) were included. WGS revealed genetic mutations in the IQCB1, PRPF31, USH2A, and GUCY2D genes in five cases (15.6%). Two large structural variations and an intronic variant were newly detected in three cases. Two individuals had biallelic missense mutations that were not identified in previous exome sequencing.

CONCLUSION

With WGS, the causative variants in 15.6% of unsolved IRDs from the Korean National Project of Bio Big Data were identified. Further research with a larger cohort might unveil the diagnostic usefulness of WGS in IRDs and other diseases.

ABCA4 variant screening in a Turkish cohort with Stargardt disease

PURPOSE

This study aims to evaluate the ABCA4 variants in patients diagnosed with Stargardt disease.

METHODS

This is a retrospective study designed to investigate variants in the ABCA4 in Stargardt disease and the clinical findings of the cases. Sex, age, age of onset of symptoms, best-corrected visual acuity, color fundus photography, optical coherence tomography, and visual field test of the patients were recorded. Genetic analyses were screened, and patients with at least two variants in the ABCA4 were included in this study.

RESULTS

Twenty-seven patients diagnosed with Stargardt disease with the ABCA4 variants were included in this study. Twelve of them (44.4%) were female and fifteen (55.5%) were male. The mean age of the cases was 27.44 years (ranging from 8 to 56 years). Thirty different variants were detected in 54 ABCA4 alleles of 27 patients. The two most common pathogenic variants were c.5882 G>A p.(Gly1961Glu) and c.52C>T p.(Arg18Trp) in this cohort. Two novel variants were identified (c.3855_3856dup, c.1554 + 3_1554 + 4del) and the patient with the c.1554 + 3_1554 + 4del variant additionally had a different ABCA4 variant in trans. The other novel variant was homozygous.

CONCLUSIONS

In this study, two novel variants were described in a Turkish cohort with Stargardt disease. The variant c.52C>T p.(Arg18Trp) was the most common disease-causing variant besides the c.5882 G>A p.(Gly1961Glu) which was identified frequently in the previous studies. A larger sample size is necessary for describing different pathogenic variants and understanding the phenotype-genotype correlations.

Stargardt macular dystrophy and therapeutic approaches

Stargardt macular dystrophy (Stargardt disease; STGD1; OMIM 248200) is the most prevalent inherited macular dystrophy. STGD1 is an autosomal recessive disorder caused by multiple pathogenic sequence variants in the large ABCA4 gene (OMIM 601691). Major advances in understanding both the clinical and molecular features, as well as the underlying pathophysiology, have culminated in many completed, ongoing and planned human clinical trials of novel therapies.The aims of this concise review are to describe (1) the detailed phenotypic and genotypic characteristics of the disease, multimodal imaging findings, natural history of the disease, and pathogenesis, (2) the multiple avenues of research and therapeutic intervention, including pharmacological, cellular therapies and diverse types of genetic therapies that have either been investigated or are under investigation and (3) the exciting novel therapeutic approaches on the translational horizon that aim to treat STGD1 by replacing the entire 6.8 kb ABCA4 open reading frame.

Inherited retinal dystrophies and orphan designations in the European Union

Inherited Retinal Dystrophies (IRD) are diverse rare diseases that affect the retina and lead to visual impairment or blindness. Research in this field is ongoing, with over 60 EU orphan medicinal products designated in this therapeutic area by the Committee for Orphan Medicinal Products (COMP) at the European Medicines Agency (EMA). Up to now, COMP has used traditional disease terms, like retinitis pigmentosa, for orphan designation regardless of the product's mechanism of action. The COMP reviewed the designation approach for IRDs taking into account all previous Orphan Designations (OD) experience in IRDs, the most relevant up to date scientific literature and input from patients and clinical experts. Following the review, the COMP decided that there should be three options available for orphan designation concerning the condition: i) an amended set of OD groups for therapies that might be used in a broad spectrum of conditions, ii) a gene-specific designation for targeted therapies, and iii) an occasional term for products that do not fit in the above two categories. The change in the approach to orphan designation in IRDs caters for different scenarios to allow an optimum approach for future OD applications including the option of a gene-specific designation. By applying this new approach, the COMP increases the regulatory clarity, efficiency, and predictability for sponsors, aligns EU regulatory tools with the latest scientific and medical developments in the field of IRDs, and ensures that all potentially treatable patients will be included in the scope of an OD.

Cost-of-illness studies of inherited retinal diseases: a systematic review

BACKGROUND

While health care and societal costs are routinely modelled for most diseases, there is a paucity of comprehensive data and cost-of-illness (COI) studies for inherited retinal diseases (IRDs). This lack of data can lead to underfunding or misallocation of resources. A comprehensive understanding of the COI of IRDs would assist governmental and healthcare leaders in determining optimal resource allocation, prioritizing funding for research, treatment, and support services for these patients.

METHODS

Following PRISMA guidelines, a literature search was conducted using Medline, EMBASE and Cochrane databases, from database inception up to 30 Jun 2023, to identify COI studies related to IRD. Original studies in English, primarily including patients with IRDs, and whose main study objective was the estimation of the costs of IRDs and had sufficiently detailed methodology to assess study quality were eligible for inclusion. To enable comparison across countries and studies, all annual costs were standardized to US dollars, adjusted for inflation to reflect their current value and recalculated on a "per patient" basis wherever possible. The review protocol was registered in PROSPERO (registration number CRD42023452986).

RESULTS

A total of nine studies were included in the final stage of systematic review and they consistently demonstrated a significant disease burden associated with IRDs. In Singapore, the mean total cost per patient was roughly US$6926/year. In Japan, the mean total cost per patient was US$20,833/year. In the UK, the mean total cost per patient with IRD ranged from US$21,658 to US$36,549/year. In contrast, in the US, the mean total per-patient costs for IRDs ranged from about US$33,017 to US$186,051 per year. In Canada, these mean total per-patient costs varied between US$16,470 and US$275,045/year. Non-health costs constituted the overwhelming majority of costs as compared to healthcare costs; 87-98% of the total costs were due to non-health costs, which could be attributed to diminished quality of life, poverty, and increased informal caregiving needs for affected individuals.

CONCLUSION

IRDs impose a disproportionate societal burden outside health systems. It is vital for continued funding into IRD research, and governments should incorporate societal costs in the evaluation of cost-effectiveness for forthcoming IRD interventions, including genomic testing and targeted therapies.

Variant reclassification and clinical implications

Genomic technologies have transformed clinical genetic testing, underlining the importance of accurate molecular genetic diagnoses. Variant classification, ranging from benign to pathogenic, is fundamental to these tests. However, variant reclassification, the process of reassigning the pathogenicity of variants over time, poses challenges to diagnostic legitimacy. This review explores the medical and scientific literature available on variant reclassification, focusing on its clinical implications.Variant reclassification is driven by accruing evidence from diverse sources, leading to variant reclassification frequency ranging from 3.6% to 58.8%. Recent studies have shown that significant changes can occur when reviewing variant classifications within 1 year after initial classification, illustrating the importance of early, accurate variant assignation for clinical care.Variants of uncertain significance (VUS) are particularly problematic. They lack clear categorisation but have influenced patient treatment despite recommendations against it. Addressing VUS reclassification is essential to enhance the credibility of genetic testing and the clinical impact. Factors affecting reclassification include standardised guidelines, clinical phenotype-genotype correlations through deep phenotyping and ancestry studies, large-scale databases and bioinformatics tools. As genomic databases grow and knowledge advances, reclassification rates are expected to change, reducing discordance in future classifications.Variant reclassification affects patient diagnosis, precision therapy and family screening. The exact patient impact is yet unknown. Understanding influencing factors and adopting standardised guidelines are vital for precise molecular genetic diagnoses, ensuring optimal patient care and minimising clinical risk.

Genetic Testing Experiences of People Living with Inherited Retinal Degenerations: Results of a Global Survey

INTRODUCTION

Obtaining a genetic diagnosis via genetic testing (GT) is a fundamental step in determining the eligibility of a patient to be enrolled in emerging clinical trials and research studies. Besides, the knowledge of genetic outcome allows patients to plan for significant life choices. However, critical barriers exist to an equitable access to genetic services globally. The objective of this study was to explore patient experiences while seeking genomic services for inherited retinal degenerations (IRDs).

METHODS

An online survey was designed based on a focus group conducted by Retina International and including people affected by IRDs and their families living in different regions around the world. The survey was then circulated to 43 Retina International member organisations globally via email newsletters and social networks. The survey involved questions in relation to the accessibility, affordability, and timeliness of genomic services for IRDs as well as patient perceived awareness of genomic services for IRDs among healthcare professionals.

RESULTS

A total of 410 respondents (IRD patients and caregivers) from over 30 countries across all continents responded to the survey. A considerable number of the patients had to go through a long and arduous journey to access GT and counselling services, wherein 40% had to visit more than 5 physicians, 27% had to visit more than 5 clinics, and 57% had to wait for more than 3 years before obtaining a genetic diagnosis. Furthermore, 46% of respondents reported not receiving genetic counselling prior to undergoing GT, and 39% reported not receiving genetic counselling after undergoing GT. Over 3/4th of the participants reported that they did not have to pay for their genomic services for IRDs. Thirty-seven percent of the respondents reported that their eye care professionals (ECPs) were either not aware of GT, remained neutral, or did not encourage them to undergo GT.

CONCLUSION

Patients with IRDs do not have equitable access to best practice GT and counselling services. Greater awareness and training regarding IRDs and the benefits of GT and genetic counselling for patients and families are needed among ECPs. A best practice model on access to genomic services for IRDs is required.

Reduced cone photoreceptor function and subtle systemic manifestations in two siblings with loss of SCLT1

BACKGROUND

The sodium channel and clathrin linker 1 gene (SCLT1) has been involved in the pathogenesis of various ciliopathy disorders such as Bardet-Biedl syndrome, orofaciodigital syndrome type IX, and Senior-Løken syndrome. Detailed exams are warranted to outline all clinical features. Here, we present a family with a milder phenotype of SCLT1-related disease.

MATERIAL AND METHODS

Comprehensive eye examination including fundus images, OCT, color vision, visual fields and electroretinography were performed. Affected individuals were assessed by a pediatrician and a medical geneticist for systemic features of ciliopathy. Investigations included echocardiography, abdominal ultrasonography, blood work-up for diabetes, liver and kidney function. Genetic testing included NGS retinal dystrophy panel, segregation analysis and transcriptome sequencing.

RESULTS

Two male children, age 10 and 8 years, were affected with attention deficit hyperactivity disorder (ADHD), obesity and mild photophobia. The ophthalmic exam revealed reduced best-corrected visual acuity (BCVA), strabismus, hyperopia, astigmatism and moderate red-green defects. Milder changes suggesting photoreceptors disease were found on retinal imaging. Electroretinogram confirmed cone photoreceptors dysfunction. Genetic testing revealed a homozygous likely pathogenic, splice-site variant in SCLT1 gene NM_144643.3: c.1439 + 1del in the proband and in the affected brother. The unaffected parents were heterozygous for the SCLT1 variant. Transcriptome sequencing showed retention of intron 16 in the proband.

CONCLUSIONS

In this report, we highlight the importance of further extensive diagnostics in patients with unexplained reduced vision, strabismus, refractive errors and ADHD spectrum disorders. SCLT1-related retinal degeneration is very rare and isolated reduced function of cone photoreceptors has not previously been observed.

Rationale and protocol paper for the Asia Pacific Network for inherited eye diseases

PURPOSE

There are major gaps in our knowledge of hereditary ocular conditions in the Asia-Pacific population, which comprises approximately 60% of the world's population. Therefore, a concerted regional effort is urgently needed to close this critical knowledge gap and apply precision medicine technology to improve the quality of lives of these patients in the Asia-Pacific region.

DESIGN

Multi-national, multi-center collaborative network.

METHODS

The Research Standing Committee of the Asia-Pacific Academy of Ophthalmology and the Asia-Pacific Society of Eye Genetics fostered this research collaboration, which brings together renowned institutions and experts for inherited eye diseases in the Asia-Pacific region. The immediate priority of the network will be inherited retinal diseases (IRDs), where there is a lack of detailed characterization of these conditions and in the number of established registries.

RESULTS

The network comprises 55 members from 35 centers, spanning 12 countries and regions, including Australia, China, India, Indonesia, Japan, South Korea, Malaysia, Nepal, Philippines, Singapore, Taiwan, and Thailand. The steering committee comprises ophthalmologists with experience in consortia for eye diseases in the Asia-Pacific region, leading ophthalmologists and vision scientists in the field of IRDs internationally, and ophthalmic geneticists.

CONCLUSIONS

The Asia Pacific Inherited Eye Disease (APIED) network aims to (1) improve genotyping capabilities and expertise to increase early and accurate genetic diagnosis of IRDs, (2) harmonise deep phenotyping practices and utilization of ontological terms, and (3) establish high-quality, multi-user, federated disease registries that will facilitate patient care, genetic counseling, and research of IRDs regionally and internationally.

The economic burden of inherited retinal disease in Singapore: a prevalence-based cost-of-illness study

OBJECTIVE

To assess the economic impact of inherited retinal disease (IRD) among Singaporeans.

METHODS

IRD prevalence was calculated using population-based data. Focused surveys were conducted for sequentially enrolled IRD patients from a tertiary hospital. The IRD cohort was compared to the age- and gender-matched general population. Economic costs were expanded to the national IRD population to estimate productivity and healthcare costs.

RESULTS

National IRD caseload was 5202 cases (95% CI, 1734-11273). IRD patients (n = 95) had similar employment rates to the general population (67.4% vs. 70.7%; p = 0.479). Annual income was lower among IRD patients than the general population (SGD 19,500 vs. 27,161; p < 0.0001). Employed IRD patients had lower median income than the general population (SGD 39,000 vs. 52,650; p < 0.0001). Per capita cost of IRD was SGD 9382, with a national burden of SGD 48.8 million per year. Male gender (beta of SGD 6543, p = 0.003) and earlier onset (beta of SGD 150/year, p = 0.009) predicted productivity loss. Treatment of the most economically impacted 10% of IRD patients with an effective IRD therapy required initial treatment cost of less than SGD 250,000 (USD 188,000) for cost savings to be achieved within 20 years.

CONCLUSIONS

Employment rates among Singaporean IRD patients were the same as the general population, but patient income was significantly lower. Economic losses were driven in part by male patients with early age of onset. Direct healthcare costs contributed relatively little to the financial burden.

RPGR-Related Retinopathy: Clinical Features, Molecular Genetics, and Gene Replacement Therapy

Retinitis pigmentosa GTPase regulator (RPGR) gene variants are the predominant cause of X-linked retinitis pigmentosa (XLRP) and a common cause of cone-rod dystrophy (CORD). XLRP presents as early as the first decade of life, with impaired night vision and constriction of peripheral visual field and rapid progression, eventually leading to blindness. In this review, we present RPGR gene structure and function, molecular genetics, animal models, RPGR-associated phenotypes and highlight emerging potential treatments such as gene-replacement therapy.

Stem cell therapy for inherited retinal diseases: a systematic review and meta-analysis

PURPOSE

Stem cell therapy is a promising therapeutic approach for inherited retinal diseases (IRDs). This study aims to quantitatively examine the effectiveness and safety of stem cell therapy for patients with IRDs, including retinitis pigmentosa and Stargardt disease (STGD).

METHODS

We searched PubMed, EMBASE, Web of Science, Cochrane Library databases, and the ClinicalTrials.gov website. The latest retrieval time was August 20, 2023. The primary outcomes were rates and mean difference (MD) of best-corrected visual acuity (BCVA) improvement. Subgroup analyses were conducted according to administration routes and stem cell types. This study was registered with PROSPERO (CRD42022349271).

RESULTS

Twenty-one prospective studies, involving 496 eyes (404 RP and 92 STGD) of 382 patients (306 RP and 76 STGD), were included in this study. For RP, the rate of BCVA improvement was 49% and 30% at 6 months and 12 months, respectively, and the BCVA was significantly improved in the operative eyes at 6 months post-treatment (MD = - 0.12 logMAR, 95% CI .17 to - 0.06 logMAR; P < 0.001), while there was no significant difference at 12 months post-treatment (MD = -0.06 logMAR; 95% CI - 0.13 to 0.01 logMAR; P = 0.10). For STGD, the rate of BCVA improvement was 60% and 55% at 6 months and 12 months, respectively, and the BCVA was significantly improved in the operative eyes at 6 months (MD = - 0.14 logMAR, 95% CI - 0.22 to - 0.07 logMAR; P = 0.0002) and 12 months (MD = - 0.17 logMAR, 95% CI - 0.29 to - 0.04 logMAR; P = 0.01). Subgroup analyses showed suprachoroidal space injection of stem cells may be more efficient for RP. Eleven treated-related ocular adverse events from three studies and no related systemic adverse events were reported.

CONCLUSIONS

This study suggests stem cell therapy may be effective and safe for patients with RP or STGD. The long-term vision improvement may be limited for RP patients. Suprachoroidal space injection of stem cells may be a promising administration route for RP patients. Limited by the low grade of evidence, large sample size randomized clinical trials are required in the future.

First-in-Human Gene Therapy Trial of AAV8-hCARp.hCNGB3 in Adults and Children With CNGB3-associated Achromatopsia

PURPOSE

To assess the safety and efficacy of AAV8-hCARp.hCNGB3 in participants with CNGB3-associated achromatopsia (ACHM).

DESIGN

Prospective, phase 1/2 (NCT03001310), open-label, nonrandomized clinical trial.

METHODS

The study enrolled 23 adults and children with CNGB3-associated ACHM. In the dose-escalation phase, adult participants were administered 1 of 3 AAV8-hCARp.hCNGB3 dose levels in the worse-seeing eye (up to 0.5 mL). After a maximum tolerated dose was established in adults, an expansion phase was conducted in children ≥3 years old. All participants received topical and oral corticosteroids. Safety and efficacy parameters, including treatment-related adverse events and visual acuity, retinal sensitivity, color vision, and light sensitivity, were assessed for 6 months.

RESULTS

AAV8-hCARp.hCNGB3 (11 adults, 12 children) was safe and generally well tolerated. Intraocular inflammation occurred in 9 of 23 participants and was mainly mild or moderate in severity. Severe cases occurred primarily at the highest dose. Two events were considered serious and dose limiting. All intraocular inflammation resolved following topical and systemic steroids. There was no consistent pattern of change from baseline to week 24 for any efficacy assessment. However, favorable changes were observed for individual participants across several assessments, including color vision (n = 6/23), photoaversion (n = 11/20), and vision-related quality-of-life questionnaires (n = 21/23).

CONCLUSIONS

AAV8-hCARp.hCNGB3 for CNGB3-associated ACHM demonstrated an acceptable safety and tolerability profile. Improvements in several efficacy parameters indicate that AAV8-hCARp.hCNGB3 gene therapy may provide benefit. These findings, with the development of additional sensitive and quantitative end points, support continued investigation.

The role of epigenetic changes in the pathology and treatment of inherited retinal diseases

Elucidation of the cellular changes that occur in degenerating photoreceptors of people with inherited retinal diseases (IRDs) has been a focus for many research teams, leading to numerous theories on how these changes affect the cell death process. What is clearly emerging from these studies is that there are common denominators across multiple models of IRD, regardless of the underlying genetic mutation. These common markers could open avenues for broad neuroprotective therapeutics to prevent photoreceptor loss and preserve functional vision. In recent years, the role of epigenetic modifications contributing to the pathology of IRDs has been a particular point of interest, due to many studies noting changes in these epigenetic modifications, which coincide with photoreceptor cell death. This review will discuss the two broad categories of epigenetic changes, DNA methylation and histone modifications, that have received particular attention in IRD models. We will review the altered epigenetic regulatory events that are believed to contribute to cell death in IRDs and discuss the therapeutic potential of targeting these alterations.

Retinal organoids provide unique insights into molecular signatures of inherited retinal disease throughout retinogenesis

The demand for induced pluripotent stem cells (iPSC)-derived retinal organoid and retinal pigment epithelium (RPE) models for the modelling of inherited retinopathies has increased significantly in the last decade. These models are comparable with foetal retinas up until the later stages of retinogenesis, expressing all of the key neuronal markers necessary for retinal function. These models have proven to be invaluable in the understanding of retinogenesis, particular in the context of patient-specific diseases. Inherited retinopathies are infamously described as clinically and phenotypically heterogeneous, such that developing gene/mutation-specific animal models in each instance of retinal disease is not financially or ethically feasible. Further to this, many animal models are insufficient in the study of disease pathogenesis due to anatomical differences and failure to recapitulate human disease phenotypes. In contrast, iPSC-derived retinal models provide a high throughput platform which is physiologically relevant for studying human health and disease. They also serve as a platform for drug screening, gene therapy approaches and in vitro toxicology of novel therapeutics in pre-clinical studies. One unique characteristic of stem cell-derived retinal models is the ability to mimic in vivo retinogenesis, providing unparalleled insights into the effects of pathogenic mutations in cells of the developing retina, in a highly accessible way. This review aims to give the reader an overview of iPSC-derived retinal organoids and/or RPE in the context of disease modelling of several inherited retinopathies including Retinitis Pigmentosa, Stargardt disease and Retinoblastoma. We describe the ability of each model to recapitulate in vivo disease phenotypes, validate previous findings from animal models and identify novel pathomechanisms that underpin individual IRDs.

Progressive Cone-Rod Dystrophy and RPE Dysfunction in Mitfmi/+ Mice

Mutations in the mouse microphthalmia-associated transcription factor (Mitf) gene affect retinal pigment epithelium (RPE) differentiation and development and can lead to hypopigmentation, microphthalmia, deafness, and blindness. For instance, an association has been established between loss-of-function mutations in the mouse Mitf gene and a variety of human retinal diseases, including Waardenburg type 2 and Tietz syndromes. Although there is evidence showing that mice with the homozygous Mitfmi mutation manifest microphthalmia and osteopetrosis, there are limited or no data on the effects of the heterozygous condition in the eye. Mitf mice can therefore be regarded as an important model system for the study of human disease. Thus, we characterized Mitfmi/+ mice at 1, 3, 12, and 18 months old in comparison with age-matched wild-type mice. The light- and dark-adapted electroretinogram (ERG) recordings showed progressive cone-rod dystrophy in Mitfmi/+ mice. The RPE response was reduced in the mutant in all age groups studied. Progressive loss of pigmentation was found in Mitfmi/+ mice. Histological retinal sections revealed evidence of retinal degeneration in Mitfmi/+ mice at older ages. For the first time, we report a mouse model of progressive cone-rod dystrophy and RPE dysfunction with a mutation in the Mitf gene.

The health care and societal costs of inherited retinal diseases in Australia: a microsimulation modelling study

OBJECTIVES

To estimate the health care and societal costs of inherited retinal diseases (IRDs) in Australia.

DESIGN, SETTING, PARTICIPANTS

Microsimulation modelling study based on primary data - collected in interviews of people with IRDs who had ophthalmic or genetic consultations at the Children's Hospital at Westmead or the Save Sight Institute (both Sydney) during 1 January 2019 - 31 December 2020, and of their carers and spouses - and linked Medicare Benefits Schedule (MBS) and Pharmaceutical Benefits Schedule (PBS) data.

MAIN OUTCOME MEASURES

Annual and lifetime costs for people with IRDs and for their carers and spouses, grouped by payer (Australian government, state governments, individuals, private health insurance) and type (health care costs; societal costs: social support, National Disability Insurance Scheme (NDIS), income and taxation, costs associated with caring for family members with IRDs); estimated annual national cost of IRDs.

RESULTS

Ninety-four people (74 adults, 20 people under 18 years; 55 girls and women [59%]) and 30 carers completed study surveys (participation rate: adults, 66%; children, 66%; carers, 63%). Total estimated lifetime cost was $5.2 million per person with an IRD, of which 87% were societal and 13% health care costs. The three highest cost items were lost income for people with IRDs ($1.4 million), lost income for their carers and spouses ($1.1 million), and social spending by the Australian government (excluding NDIS expenses: $1.0 million). Annual costs were twice as high for people who were legally blind as for those with less impaired vision ($83 910 v $41 357 per person). The estimated total annual cost of IRDs in Australia was $781 million to $1.56 billion.

CONCLUSION

As the societal costs associated with IRDs are much larger than the health care costs, both contributors should be considered when assessing the cost-effectiveness of interventions for people with IRDs. The increasing loss of income across life reflects the impact of IRDs on employment and career opportunities.

Quality of Life and Economic Impacts of Retinitis Pigmentosa on Japanese Patients: A Non-interventional Cross-sectional Study

INTRODUCTION

Retinitis pigmentosa (RP) is an inherited progressive disease, characterized by a loss of photoreceptors, and is the second leading cause of visual impairment in Japan. RP is currently incurable and can result in complete blindness, with affected patients typically experiencing a gradual loss of light sensitivity, visual field, and visual acuity. Identification of any unmet medical needs of patients with this condition requires an understanding of the impacts of RP; in this study, we surveyed Japanese patients with RP to investigate the quality of life and economic impacts of visual impairment.

METHODS

This non-interventional, cross-sectional study surveyed Japanese patients with RP. Economic impact was measured using an original questionnaire that assessed out-of-pocket cost (e.g., vision aids and medical services), salary gap with the general public, and the cost of depression and anxiety. Worker productivity was assessed using the Work Productivity and Activity Impairment Questionnaire (WPAI). Quality of life was evaluated using the Health Utilities Index Mark 3 (HUI3), the National Eye Institute Visual Function Questionnaire-25 (VFQ-25), and the 5-level EQ-5D version (EQ-5D-5L). The primary outcome was direct and indirect costs of visual impairment or blindness during the lifetime of patients with RP.

RESULTS

Among 122 surveyed patients with RP, the estimated annual cost per patient was 218,520 yen (2176 USD), and the estimated lifetime cost per patient was 18,523,909 yen (184,501 USD). Additional robustness testing increased the estimated annual cost and lifetime cost per patient to 783,176 yen (7801 USD) and 66,389,827 yen (661,253 USD), respectively. In working patients, work productivity loss was 26.2% per person and impairment of daily activities was 31.6% per person. The mean VFQ-25, HUI3, and EQ-5D-5L scores were 42.0, 0.393, and 0.833, respectively.

CONCLUSION

RP imposed a heavy economic burden and negative quality of life impacts in Japanese patients.

Can artificial intelligence accelerate the diagnosis of inherited retinal diseases? Protocol for a data-only retrospective cohort study (Eye2Gene)

INTRODUCTION

Inherited retinal diseases (IRD) are a leading cause of visual impairment and blindness in the working age population. Mutations in over 300 genes have been found to be associated with IRDs and identifying the affected gene in patients by molecular genetic testing is the first step towards effective care and patient management. However, genetic diagnosis is currently slow, expensive and not widely accessible. The aim of the current project is to address the evidence gap in IRD diagnosis with an AI algorithm, Eye2Gene, to accelerate and democratise the IRD diagnosis service.

METHODS AND ANALYSIS

The data-only retrospective cohort study involves a target sample size of 10 000 participants, which has been derived based on the number of participants with IRD at three leading UK eye hospitals: Moorfields Eye Hospital (MEH), Oxford University Hospital (OUH) and Liverpool University Hospital (LUH), as well as a Japanese hospital, the Tokyo Medical Centre (TMC). Eye2Gene aims to predict causative genes from retinal images of patients with a diagnosis of IRD. For this purpose, 36 most common causative IRD genes have been selected to develop a training dataset for the software to have enough examples for training and validation for detection of each gene. The Eye2Gene algorithm is composed of multiple deep convolutional neural networks, which will be trained on MEH IRD datasets, and externally validated on OUH, LUH and TMC.

ETHICS AND DISSEMINATION

This research was approved by the IRB and the UK Health Research Authority (Research Ethics Committee reference 22/WA/0049) 'Eye2Gene: accelerating the diagnosis of IRDs' Integrated Research Application System (IRAS) project ID: 242050. All research adhered to the tenets of the Declaration of Helsinki. Findings will be reported in an open-access format.

Current Management of Patients with RPE65 Mutation Associated Inherited Retinal Degenerations in Europe: Results of a 2-Year Follow-Up Multinational Survey

INTRODUCTION

The aim of this study was to evaluate the current management of RPE65 biallelic mutation-associated inherited retinal degeneration (RPE65-IRD) in Europe since market authorization of voretigene neparvovec (VN, LuxturnaTM) in 2018. By July 2022, over 200 patients have been treated outside the USA, of whom about 90% in Europe. We conducted among all centers of the European Vision Institute Clinical Research Network (EVICR.net) and health care providers (HCPs) of the European Reference Network dedicated to Rare Eye Diseases (ERN-EYE) the second multinational survey on management of IRDs in Europe elaborated by EVICR.net with a special focus on RPE65-IRD.

METHODS

An electronic survey questionnaire with 48 questions specifically addressing RPE65-IRD (2019 survey 35) was developed and sent by June 2021 to 95 EVICR.net centers and 40 ERN-EYE HCPs and affiliated members. Of note, 11 centers are members of both networks. Statistical analysis was performed with Excel and R.

RESULTS

The overall response rate was 44% (55/124); 26 centers follow RPE65 biallelic mutation-associated IRD patients. By June 2021, 8/26 centers have treated 57 RPE65-IRD cases (1-19/center, median 6) and 43 planned for treatment (range 0-10/center, median 6). The overall age range was 3-52 years, and on average 22% of the patients did not (yet) qualify for treatment (range 2-60%/center, median 15%). Main reasons were too advanced (range 0-100, median 75%) or mild disease (range 0-100, median 0). Eighty-three percent of centers (10/12) that follow RPE65 mutation-associated IRD patients treated with VN participate in the PERCEIVE registry (EUPAS31153, http://www.encepp.eu/encepp/viewResource.htm?id=37005). Quality of life and full-field stimulus test improvements had the highest scores of the survey-reported outcome parameters in VN treatment follow-up.

CONCLUSION

This second multinational survey on management of RPE65-IRD by EVICR.net centers and ERN-EYE HCPs in Europe indicates that RPE65-IRD might be diagnosed more reliably in 2021 compared to 2019. By June 2021, 8/26 centers reported detailed results including VN treatment. Main reasons for non-treatment were too advanced or mild disease, followed by absence of 2 class 4 or 5 mutations on both alleles or because of a too young age. Patient satisfaction with treatment was estimated to be high by 50% of the centers.

Denuded Descemet's membrane supports human embryonic stem cell-derived retinal pigment epithelial cell culture

Recent clinical studies suggest that retinal pigment epithelial (RPE) cell replacement therapy may preserve vision in retinal degenerative diseases. Scaffold-based methods are being tested in ongoing clinical trials for delivering pluripotent-derived RPE cells to the back of the eye. The aim of this study was to investigate human embryonic stem cell-derived retinal pigment epithelial (hESC-RPE) cells survival and behaviour on a decellularized Descemet's Membrane (DM), which may be of clinical relevance in retinal transplantation. DMs were isolated from human donor corneas and treated with thermolysin. The DM surface topology and the efficiency of the denudation method were evaluated by atomic force microscope, scanning electron microscopy and histology. hESC-RPE cells were seeded onto the endothelial-side surface of decellularized DM in order to determine the potential of the membrane to support hESC-RPE cell culture, alongside maintaining their viability. Integrity of the hESC-RPE monolayer was assessed by measuring transepithelial resistance. RPE-specific gene expression and growth factors secretion were assessed to confirm maturation and functionality of the cells over the new substrate. Thermolysin treatment did not affect the integrity of the tissue, thus ensuring a reliable method to standardize the preparation of decellularized DM. 24 hours post-seeding, hESC-RPE cell attachment and initial proliferation rate over the denuded DM were higher than hESC-RPE cells cultured on tissue culture inserts. On the new matrix, hESC-RPE cells succeeded in forming an intact monolayer with mature tight junctions. The resulting cell culture showed characteristic RPE cell morphology and proper protein localization. Gene expression analysis and VEGF secretion demonstrate DM provides supportive scaffolding and inductive properties to enhance hESC-RPE cells maturation. Decellularized DM was shown to be capable of sustaining hESC-RPE cells culture, thus confirming to be potentially a suitable candidate for retinal cell therapy.

Longitudinal analysis of health care costs in patients with childhood onset inherited retinal dystrophies compared to healthy controls

BACKGROUND

We evaluated health care costs in patients with childhood onset visual impairment caused by inherited retinal dystrophies (IRD).

METHODS

The IRD cohort, identified from the Danish Registry of Blind and Partially Sighted Children, was compared to age- and sex-matched controls from the national, Danish population registry. Information on health care expenditures for somatic and psychiatric in- and outpatient services, purchase of prescription medications and paid assistance at home were obtained from national registries for the years 2002-2017.

RESULTS

We included 412 in the IRD cohort (6,290 person years) and 1656 (25,088 person years) in the control cohort. Average, annual health care expenditures from age 0-48 years of age were €1,488 (SD 4,711) in the IRD cohort and €1,030 (4,639) in the control cohort. The largest difference was for out-patient eye care (13.26 times greater, 95% confidence interval 12.90-13.64). Psychiatric in-patient expenditures were 1.71 times greater (95% CI 1.66-1.76) in the IRD cohort but psychiatric out-patient health care costs were comparable between groups.

CONCLUSIONS

Health care costs were approximately 40% greater in the IRD cohort compared to an age- and sex-matched sample from the general Danish population. This is relevant in the current situation with a number of trials aimed at treating IRDs using genetically based therapies. Although eye care expenditures were many times greater, they made up < 10% of the total health care expenditures even in the IRD cohort. The reduced costs related to injuries in the visually impaired cohort was a surprising finding but may reflect a reduced propensity to seek medical care rather than a reduced risk of injuries.

Proteostasis in aging-associated ocular disease

Vision impairment has devastating consequences for the quality of human life. The cells and tissues associated with the visual process must function throughout one's life span and maintain homeostasis despite exposure to a variety of insults. Maintenance of the proteome is termed proteostasis, and is vital for normal cellular functions, especially at an advanced age. Here we describe basic aspects of proteostasis, from protein synthesis and folding to degradation, and discuss the current status of the field with a particular focus on major age-related eye diseases: age-related macular degeneration, cataract, and glaucoma. Our intent is to allow vision scientists to determine where and how to harness the proteostatic machinery for extending functional homeostasis in the aging retina, lens, and trabecular meshwork. Several common themes have emerged despite these tissues having vastly different metabolisms. Continued exposure to insults, including chronic stress with advancing age, increases proteostatic burden and reduces the fidelity of the degradation machineries including the ubiquitin-proteasome and the autophagy-lysosome systems that recognize and remove damaged proteins. This "double jeopardy" results in an exponential accumulation of cytotoxic proteins with advancing age. We conclude with a discussion of the challenges in maintaining an appropriate balance of protein synthesis and degradation pathways, and suggest that harnessing proteostatic capacities should provide new opportunities to design interventions for attenuating age-related eye diseases before they limit sight.

A qualitative interview study of the attitudes toward reproductive options of people with genetic visual loss

In the United Kingdom (U.K), 2.19 million people are affected by visual loss. Monogenic causes of visual loss include retinal dystrophies, optic neuropathies, and congenital glaucoma. A variety of reproductive options are available to adults with genetic visual loss to permit them to have an unaffected child. Prenatal diagnostic testing (PND) via amniocentesis or chorionic villus sampling (CVS) or Preimplantation Genetic Testing (PGT) is possible, provided the causal genetic variants are known in the family. We report a qualitative interview study of people with genetic causes of visual loss to explore their attitudes toward reproductive options. Participants reported a range of challenges associated with living with genetic conditions associated with visual loss. These had the potential to shape attitudes to reproductive options. Participants expressed enthusiasm for genetic testing, as it enabled them to understand if relatives might be affected by the visual loss. Decisions around reproductive options were recognized as challenging and highly personal. Positive opinions of PGT were reported, as it permitted conception of a child without the genetic cause of visual loss while avoiding the need for the termination of pregnancy. The provision of accessible information resources on genetics and reproductive options was reported to be important.

Multidisciplinary team directed analysis of whole genome sequencing reveals pathogenic non-coding variants in molecularly undiagnosed inherited retinal dystrophies

The purpose of this paper is to identify likely pathogenic non-coding variants in inherited retinal dystrophy (IRD) genes, using genome sequencing (GS). Patients with IRD were recruited to the study and underwent comprehensive ophthalmological evaluation and GS. The results of GS were investigated through virtual gene panel analysis, and plausible pathogenic variants and clinical phenotype evaluated by the multidisciplinary team (MDT) discussion. For unsolved patients in whom a specific gene was suspected to harbor a missed pathogenic variant, targeted re-analysis of non-coding regions was performed on GS data. Candidate variants were functionally tested by messenger RNA analysis, minigene or luciferase reporter assays. Previously unreported, likely pathogenic, non-coding variants in 7 genes (PRPF31, NDP, IFT140, CRB1, USH2A, BBS10 and GUCY2D), were identified in 11 patients. These were shown to lead to mis-splicing (PRPF31, IFT140, CRB1 and USH2A) or altered transcription levels (BBS10 and GUCY2D). MDT-led, phenotype-driven, non-coding variant re-analysis of GS is effective in identifying the missing causative alleles.

Increased H3K27 trimethylation contributes to cone survival in a mouse model of cone dystrophy

Inherited retinal diseases (IRDs) are a heterogeneous group of blinding disorders, which result in dysfunction or death of the light-sensing cone and rod photoreceptors. Despite individual IRDs (Inherited retinal disease) being rare, collectively, they affect up to 1:2000 people worldwide, causing a significant socioeconomic burden, especially when cone-mediated central vision is affected. This study uses the Pde6c^cpfl1 mouse model of achromatopsia, a cone-specific vision loss IRD (Inherited retinal disease), to investigate the potential gene-independent therapeutic benefits of a histone demethylase inhibitor GSK-J4 on cone cell survival. We investigated the effects of GSK-J4 treatment on cone cell survival in vivo and ex vivo and changes in cone-specific gene expression via single-cell RNA sequencing. A single intravitreal GSK-J4 injection led to transcriptional changes in pathways involved in mitochondrial dysfunction, endoplasmic reticulum stress, among other key epigenetic pathways, highlighting the complex interplay between methylation and acetylation in healthy and diseased cones. Furthermore, continuous administration of GSK-J4 in retinal explants increased cone survival. Our results suggest that IRD (Inherited retinal disease)-affected cones respond positively to epigenetic modulation of histones, indicating the potential of this approach in developing a broad class of novel therapies to slow cone degeneration.

Valuing the "Burden" and Impact of Rare Diseases: A Scoping Review

Introduction: Rare diseases (RDs) are a severe, chronic, degenerative and often life-threatening group of conditions affecting more than 30 million people in Europe. Their impact is often underreported and ranges from psychological and physical symptoms seriously compromising quality of life. There is then a need to consolidate knowledge on the economic, social, and quality of life impacts of rare diseases.

Methods: This scoping review is the result of 9 qualitative interviews with experts and a literature search on Cost-of-Illness (COI) studies and quality of life (QoL) studies following the PRISMA methodology. Grey literature was also included to complement findings. Results. 63 COI studies were retrieved, covering 42 diseases and a vast majority of them using a prevalence-based approach (94%). All studies included medical costs, while 60% included non-medical costs, 68% productivity losses and 43% informal care costs. 56 studies on QoL were retrieved, mostly from Europe, with 30 different measurement tools. Grey literature included surveys from the pharmaceutical industry and patient organisations.

Discussion: The majority of studies evaluating the impact of RDs on the individual and society use the COI approach, mostly from a societal perspective. Studies often vary in scope, making them difficult to consolidate or compare results. While medical costs and productivity losses are consistently included, QoL aspects are rarely considered in COI and are usually measured through generic tools.

Conclusion: A comprehensive study on impact of rare disease across countries in Europe is lacking. Existing studies are heterogeneous in their scope and methodology and often lack a holistic picture of the impact of rare. Consensus on standards and methodology across countries and diseases is then needed. Studies that consider a holistic approach are often conducted by pharmaceutical companies and patient organisations exploring a specific disease area but are not necessarily visible in the literature and could benefit from the sharing of standards and best practices.

Childhood-onset retinal dystrophies reduces life-time income by one third - an individual based socio-economic analysis

BACKGROUND

The aim of this study was to evaluate lifetime income, educational level and workforce participation in patients with childhood-onset inherited retinal dystrophies (IRD).

MATERIAL AND METHODS

The registry-based study using national, Danish databases on education, income, employment and social benefits in a cohort of 515 patients with childhood-onset IRD and without severe systemic comorbidities matched 1:4 to an age- and sex to a control sample of the Danish background population. Socio-economic status was modelled with focus on grade mark points after primary education, highest attained education at 30 years or age, employment and unemployment rate, disability pension and lifetime income.

RESULTS

At 30 years of age, the proportion of those who had primary education as the highest achieved level was higher in the IRD group (35.4% versus 18.7%) and they were more likely to be receiving a disability pension (OR 11.77) or be unemployed (OR 6.63). Those at work had the same number of work hours as the control group, and the same proportion had obtained a Master or PhD degree (14%). At 30 years of age, income earnings were lower in the IRD group and the lifetime income was reduced by 30%.

CONCLUSION

A few among those with childhood-onset IRD were able to obtain high educational levels, and many were assigned a disability pension from early adulthood or were unemployed, resulting in a markedly reduced lifetime income although grade mark points from primary education were comparable, suggesting that the difference was not explained by intellectual differences between the groups.

Optogenetics for visual restoration: From proof of principle to translational challenges

Degenerative retinal disorders are a diverse family of diseases commonly leading to irreversible photoreceptor death, while leaving the inner retina relatively intact. Over recent years, innovative gene replacement therapies aiming to halt the progression of certain inherited retinal disorders have made their way into clinics. By rendering surviving retinal neurons light sensitive optogenetic gene therapy now offers a feasible treatment option that can restore lost vision, even in late disease stages and widely independent of the underlying cause of degeneration. Since proof-of-concept almost fifteen years ago, this field has rapidly evolved and a detailed first report on a treated patient has recently been published. In this article, we provide a review of optogenetic approaches for vision restoration. We discuss the currently available optogenetic tools and their relative advantages and disadvantages. Possible cellular targets will be discussed and we will address the question how retinal remodelling may affect the choice of the target and to what extent it may limit the outcomes of optogenetic vision restoration. Finally, we will analyse the evidence for and against optogenetic tool mediated toxicity and will discuss the challenges associated with clinical translation of this promising therapeutic concept.

Electrophysiology-Guided Genetic Characterisation Maximises Molecular Diagnosis in an Irish Paediatric Inherited Retinal Degeneration Population

Inherited retinal degenerations (IRDs) account for over one third of the underlying causes of blindness in the paediatric population. Patients with IRDs often experience long delays prior to reaching a definitive diagnosis. Children attending a tertiary care paediatric ophthalmology department with phenotypic (i.e., clinical and/or electrophysiologic) evidence suggestive of IRD were contacted for genetic testing during the SARS-CoV-2-19 pandemic using a “telegenetics” approach. Genetic testing approach was panel-based next generation sequencing (351 genes) via a commercial laboratory (Blueprint Genetics, Helsinki, Finland). Of 70 patient samples from 57 pedigrees undergoing genetic testing, a causative genetic variant(s) was detected for 60 patients (85.7%) from 47 (82.5%) pedigrees. Of the 60 genetically resolved IRD patients, 5% (n = 3) are eligible for approved therapies (RPE65) and 38.3% (n = 23) are eligible for clinical trial-based gene therapies including CEP290 (n = 2), CNGA3 (n = 3), CNGB3 (n = 6), RPGR (n = 5) and RS1 (n = 7). The early introduction of genetic testing in the diagnostic/care pathway for children with IRDs is critical for genetic counselling of these families prior to upcoming gene therapy trials. Herein, we describe the pathway used, the clinical and genetic findings, and the therapeutic implications of the first systematic coordinated round of genetic testing of a paediatric IRD cohort in Ireland.

The current state of genetic testing platforms for inherited retinal diseases

PURPOSE

To evaluate genetic testing platforms used to aid in the diagnosis of inherited retinal degenerations (IRDs).

DESIGN

Evaluation of diagnostic test or technology SUBJECTS: Targeted genetic panel testing for IRDs METHODS, INTERVENTION, OR TESTING: Data collected regarding targeted genetic panel testing for IRDs offered by different labs were investigated for inclusion of coding and non-coding variants in disease genes. Both large IRD panels and smaller, more focused disease specific panels were included in the analysis.

MAIN OUTCOME MEASURES

Number of disease genes tested as well as the commonality and uniqueness across testing platforms in both coding and non-coding variants of disease.

RESULTS

Across the three IRD panel tests investigated, 409 unique genes are represented, of which 269 genes are tested by all three panels. The top 20 genes known to cause over 70% of all IRDs are represented in the 269 common genes tested by all three panels. In addition, 138 non-coding variants are assayed across the three platforms in 50 unique genes. Focused disease specific panels exhibited significant variability across 5 testing platforms that were studied.

CONCLUSIONS

Ordering genetic testing for IRDs is not straightforward, as evidenced by the multitude of panels available to providers. It is important that there is coverage of both coding and non-coding regions in IRD genes to offer a diagnosis in these patients. This paper details the diversity of testing platforms currently available to clinicians and provides a thorough explanation of genes tested in the different IRD panels. In a time of increased importance for clinical genetic testing of IRD patients, knowledge of the proper test to order is paramount.

Epidemiology of Mutations in the 65-kDa Retinal Pigment Epithelium (RPE65) Gene-Mediated Inherited Retinal Dystrophies: A Systematic Literature Review

INTRODUCTION

Inherited retinal dystrophies (IRDs) represent a genetically diverse group of progressive, visually debilitating diseases. Adult and paediatric patients with vision loss due to IRD caused by biallelic mutations in the 65-kDa retinal pigment epithelium (RPE65) gene are often clinically diagnosed as retinitis pigmentosa (RP), and Leber congenital amaurosis (LCA). This study aimed to understand the epidemiological landscape of RPE65 gene-mediated IRD through a systematic review of the literature, as the current evidence base for its epidemiology is very limited.

METHODS

Medline, Embase, and other databases were searched for articles on the epidemiology of RPE65 gene-mediated IRDs from inception until June 2021. Studies were included if they were original research articles reporting the epidemiology of RP and LCA and/or proportion of RPE65 gene mutations in these clinically diagnosed or molecularly confirmed IRDs patients.

RESULTS

A total of 100 studies with relevant data were included in this systematic review. The range for prevalence of LCA and RP in the literature was 1.20-2.37 and 11.09-26.43 per 100,000, respectively. The proportion of RPE65 mutations in clinically diagnosed patients with LCA was found to be between ~ 2-16% within the US and major European countries (France, Germany, Italy, Spain, and the UK). This range was also comparable to our findings in the Asian region for RPE65-LCA (1.26-16.67%). Similarly, for these European countries, RPE65-RP was estimated between 0.23 and 1.94%, and RPE65-IRD range was 1.2-14%. Further, in the Americas region, mutations in RPE65 were reported to cause 1-3% of RP and 0.8-3.7% of IRD cases. Lastly, the RPE65-IRD range was 4.81-8% in the Middle East region.

CONCLUSIONS

There are significant variations in reporting of RPE65 proportions within countries as well as regions. Generating robust epidemiological evidence on RPE65 gene-mediated IRDs would be fundamental to support rare disease awareness, timely therapeutic intervention, and public health decision-making.

Rod genesis driven by mafba in an nrl knockout zebrafish model with altered photoreceptor composition and progressive retinal degeneration

Neural retina leucine zipper (NRL) is an essential gene for the fate determination and differentiation of the precursor cells into rod photoreceptors in mammals. Mutations in NRL are associated with the autosomal recessive enhanced S-cone syndrome and autosomal dominant retinitis pigmentosa. However, the exact role of Nrl in regulating the development and maintenance of photoreceptors in the zebrafish (Danio rerio), a popular animal model used for retinal degeneration and regeneration studies, has not been fully determined. In this study, we generated an nrl knockout zebrafish model via the CRISPR-Cas9 technology and observed a surprising phenotype characterized by a reduced number, but not the total loss, of rods and over-growth of green cones. We discovered two waves of rod genesis, nrl-dependent and -independent at the embryonic and post-embryonic stages, respectively, in zebrafish by monitoring the rod development. Through bulk and single-cell RNA sequencing, we characterized the gene expression profiles of the whole retina and each retinal cell type from the wild type and nrl knockout zebrafish. The over-growth of green cones and mis-expression of green-cone-specific genes in rods in nrl mutants suggested that there are rod/green-cone bipotent precursors, whose fate choice between rod versus green-cone is controlled by nrl. Besides, we identified the mafba gene as a novel regulator of the nrl-independent rod development, based on the cell-type-specific expression patterns and the retinal phenotype of nrl/mafba double-knockout zebrafish. Gene collinearity analysis revealed the evolutionary origin of mafba and suggested that the function of mafba in rod development is specific to modern fishes. Furthermore, the altered photoreceptor composition and abnormal gene expression in nrl mutants caused progressive retinal degeneration and subsequent regeneration. Accordingly, this study revealed a novel function of the mafba gene in rod development and established a working model for the developmental and regulatory mechanisms regarding the rod and green-cone photoreceptors in zebrafish.

Vision is mediated by two types of light-sensing cells named rod and cone photoreceptors in animal eyes. Abnormal generation, dysfunction or death of photoreceptor cells all cause irreversible vision problems. NRL is an essential gene for the generation and function of rod cells in mice and humans. Surprisingly, we found that in the zebrafish, a popular animal model for human diseases and therapeutic testing, there are two types of rod cells, and eliminating the function of nrl gene affects the rod cell formation at the embryonic stage but not at the juvenile and adult stages. The rod cell formation at the post-embryonic is driven by the mafba gene, which has not been reported to play a role in rod cells. In addition to the reduced number of rod cells, deletion of nrl also results in the emergence of rod/green-cone hybrid cells and an increased number of green cones. The ensuing cellular and molecular alterations collectively lead to retinal degeneration. These findings expand our understanding of photoreceptor development and maintenance and highlight the underlying conserved and species-specific regulatory mechanisms.

Collaborative Research and Development of a Novel, Patient-Centered Digital Platform (MyEyeSite) for Rare Inherited Retinal Disease Data: Acceptability and Feasibility Study

BACKGROUND

Inherited retinal diseases (IRDs) are a leading cause of blindness in children and working age adults in the United Kingdom and other countries, with an appreciable socioeconomic impact. However, by definition, IRD data are individually rare, and as a result, this patient group has been underserved by research. Researchers need larger amounts of these rare data to make progress in this field, for example, through the development of gene therapies. The challenge has been how to find and make these data available to researchers in the most productive way. MyEyeSite is a research collaboration aiming to design and develop a digital platform (the MyEyeSite platform) for people with rare IRDs that will enable patients, doctors, and researchers to aggregate and share specialist eye health data. A crucial component of this platform is the MyEyeSite patient application, which will provide the means for patients with IRD to interact with the system and, in particular, to collate, manage, and share their personal specialist IRD data both for research and their own health care.

OBJECTIVE

This study aims to test the acceptability and feasibility of the MyEyeSite platform in the target IRD population through a collaborative patient-centered study.

METHODS

Qualitative data were generated through focus groups and workshops, and quantitative data were obtained through a survey of patients with IRD. Participants were recruited through clinics at Moorfields Eye Hospital National Health Service (NHS) Foundation Trust and the National Institute for Health Research (NIHR) Moorfields Biomedical Research Centre through their patient and public involvement databases.

RESULTS

Our IRD focus group sample (n=50) highlighted the following themes: frustration with the current system regarding data sharing within the United Kingdom's NHS; positive expectations of the potential benefits of the MyEyeSite patient application, resulting from increased access to this specialized data; and concerns regarding data security, including potentially unethical use of the data outside the NHS. Of the surveyed 80 participants, 68 (85%) were motivated to have a more active role in their eye care and share their data for research purposes using a secure technology, such as a web application or mobile app.

CONCLUSIONS

This study demonstrates that patients with IRD are highly motivated to be actively involved in managing their own data for research and their own eye care. It demonstrates the feasibility of involving patients with IRD in the detailed design of the MyEyeSite platform exemplar, with input from the patient with IRD workshops playing a key role in determining both the functionality and accessibility of the designs and prototypes. The development of a user-centered technological solution to the problem of rare health data has the potential to benefit not only the patient with IRD community but also others with rare diseases.

Gene-Based Therapeutics for Inherited Retinal Diseases

Inherited retinal diseases (IRDs) are a heterogenous group of orphan eye diseases that typically result from monogenic mutations and are considered attractive targets for gene-based therapeutics. Following the approval of an IRD gene replacement therapy for Leber's congenital amaurosis due to RPE65 mutations, there has been an intensive international research effort to identify the optimal gene therapy approaches for a range of IRDs and many are now undergoing clinical trials. In this review we explore therapeutic challenges posed by IRDs and review current and future approaches that may be applicable to different subsets of IRD mutations. Emphasis is placed on five distinct approaches to gene-based therapy that have potential to treat the full spectrum of IRDs: 1) gene replacement using adeno-associated virus (AAV) and nonviral delivery vectors, 2) genome editing via the CRISPR/Cas9 system, 3) RNA editing by endogenous and exogenous ADAR, 4) mRNA targeting with antisense oligonucleotides for gene knockdown and splicing modification, and 5) optogenetic approaches that aim to replace the function of native retinal photoreceptors by engineering other retinal cell types to become capable of phototransduction.

Blindness and visual impairment in Central Europe

Purpose

To assess the prevalence and causes of visual impairment and blindness in a Central European country. The findings may have implications for the planning of further research and development of therapies in order to prevent blindness.

Setting

Department of Ophthalmology, Medical University of Graz, Austria.

Design

Retrospective, epidemiological study.

Methods

The database of the Main Confederation of Austrian Social Insurances was searched for patients with visual impairment, legal blindness or deaf-blindness. This database gathers data from patients of all insurance providers in the country who receive care due to visual impairment and blindness. To determine the prevalence of these conditions, the number of all entries recorded in February 2019 was evaluated. Additionally, all new entries between (January 1^st,) 2017, and (December 31^st,) 2018, were analysed for distinct characteristics, such as sex, the cause of blindness/visual impairment, and age. Since health care allowances can provide a considerable source of income (459.90€-936.90€ per month), good coverage of practically all patients who are blind and visually impaired in the country can be assumed.

Results

On February 2^nd, 2019, 17,730 patients with visual impairments, blindness or deaf-blindness were registered in Austria, resulting in a prevalence of these diagnoses of 0.2% in the country. During the observational period from 2017 to 2018, 4040 persons met the inclusion criteria. Of these, 2877 were female (65.3%), and 1527 were male (34.7%). The mean age was 75.7 ± 18.0 years (median 82). Most patients (n = 3675, 83.4%) were of retirement age, while 729 (16.6%) were working-age adults or minors. In total, an incidence of 25.0 (95% confidence limit (CL) 24.3–25.8) per 100,000 person-years was observed from 2017 to 2018. A higher incidence was observed for females (32.2, 95% CL 31.0–33.3) than for males (17.7, 95% CL 16.8–18.5). Incidences where higher for males in lower age groups (e.g. 10–14 years: rate ratio RR = 2.7, 95% CL 1.1–6.8), and higher for females in higher age groups (e.g. 70–74 years: RR = 0.6, 95% CL 0.5–0.8). In total, the most frequent diagnoses were macular degeneration (1075 persons, 24.4%), other retinal disorders (493 persons, 11.2%) and inherited retinal and choroidal diseases (IRDs) (186 persons, 4.2%). Persons with IRDs were significantly younger compared to persons with macular degeneration or retinal disorders (IRDs: median 57, range 2–96 vs 83, 5–98 and 82, 1–98 years, p<0.001). For persons of retirement age, macular degeneration, other retinal disorders and glaucoma were the three most frequent diagnoses. In contrast, among working-aged adults and children, IRDs were the leading cause of visual impairment and blindness (103 persons, 14.1%).

Conclusion

These data show that IRDs are the leading cause of blindness and visual impairment in working-aged persons and children in Austria. Thus, these findings suggest to draw attention to enhance further research in the fields of emerging therapies for IRDs.

RNA-based therapies in inherited retinal diseases

Inherited retinal diseases (IRDs) are a genetically and phenotypically heterogeneous group of genetic eye disorders. There are more than 300 disease entities, and together this group of disorders affects millions of people globally and is a frequent cause of blindness or low-vision certification. However, each type is rare or ultra-rare. Characteristically, the impaired vision in IRDs is due to retinal photoreceptor dysfunction and loss resulting from mutation in a gene that codes for a retinal protein. Historically, IRDs have been considered incurable and individuals living with these blinding conditions could be offered only supportive care. However, the treatment landscape for IRDs is beginning to evolve. Progress is being made, driven by improvements in understanding of genotype-phenotype relationships, through advances in molecular genetic testing and retinal imaging. Alongside this expanding knowledge of IRDs, the current era of precision medicine is fueling a growth in targeted therapies. This has resulted in the first treatment for an IRD being approved. Several other therapies are currently in development in the IRD space, including RNA-based therapies, gene-based therapies (such as augmentation therapy and gene editing), cell therapy, visual prosthetics, and optogenetics. RNA-based therapies are a novel approach within precision medicine that have demonstrated success, particularly in rare diseases. Three antisense oligonucleotides (AONs) are currently in development for the treatment of specific IRD subtypes. These RNA-based therapies bring several key advantages in the setting of IRDs, and the potential to bring meaningful vision benefit to individuals living with inherited blinding disorders. This review will examine the increasing breadth and relevance of RNA-based therapies in clinical medicine, explore the key features that make AONs suitable for treating genetic eye diseases, and provide an overview of the three-leading investigational AONs in clinical trials.

Victorian evolution of inherited retinal diseases natural history registry (VENTURE study): Rationale, methodology and initial participant characteristics

BACKGROUND

Emerging treatments are being developed for inherited retinal diseases, requiring a clear understanding of natural progression and a database of potential participants for clinical trials. This article describes the rationale, study design and methodology of the Victorian Evolution of inherited retinal diseases NaTUral history REgistry (VENTURE), including data from the first 150 participants enrolled.

METHODS

VENTURE collects retrospective and prospective data from people with inherited retinal diseases. Following registration, participants are asked to attend a baseline examination using a standardised protocol to confirm their inherited retinal disease diagnosis. Examination procedures include (i) retinal function, using visual acuity and perimetry; (ii) retinal structure, using multimodal imaging and (iii) patient-reported outcomes. Participants' molecular diagnoses are obtained from their clinical records or through targeted-panel genetic testing by an independent laboratory. Phenotype and genotype data are used to enrol participants into disease-specific longitudinal cohort sub-studies.

RESULTS

From 7 July 2020 to 30 December 2021, VENTURE enrolled 150 registrants (138 families) and most (63%) have a rod-cone dystrophy phenotype. From 93 participants who have received a probable molecular diagnosis, the most common affected genes are RPGR (13% of all registrants), USH2A (10%), CYP4V2 (7%), ABCA4 (5%), and CHM (5%). Most participants have early to moderate vision impairment, with over half (55%) having visual acuities of better than 6/60 (20/200) at registration.

CONCLUSIONS

The VENTURE study will complement existing patient registries and help drive inherited retinal disease research in Australia, facilitating access to research opportunities for individuals with inherited retinal diseases.

Structural evaluation in inherited retinal diseases

Ophthalmic genetics is a field that has been rapidly evolving over the last decade, mainly due to the flourishing of translational medicine for inherited retinal diseases (IRD). In this review, we will address the different methods by which retinal structure can be objectively and accurately assessed in IRD. We review standard-of-care imaging for these patients: colour fundus photography, fundus autofluorescence imaging and optical coherence tomography (OCT), as well as higher-resolution and/or newer technologies including OCT angiography, adaptive optics imaging, fundus imaging using a range of wavelengths, magnetic resonance imaging, laser speckle flowgraphy and retinal oximetry, illustrating their utility using paradigm genotypes with on-going therapeutic efforts/trials.

The future of retinal gene therapy: evolving from subretinal to intravitreal vector delivery

Inherited retinal degenerations are a leading and untreatbale cause of blindness, and as such they are targets for gene therapy. Numerous gene therapy treatments have progressed from laboratory research to clinical trails, and a pioneering gene therapy received the first ever FDA approval for treating patients. However, currently retinal gene therapy mostly involves subretinal injection of the therapeutic agent, which treats a limited area, entails retinal detachment and other potential complications, and requires general anesthesia with consequent risks, costs and prolonged recovery. Therefore there is great impetus to develop safer, less invasive and cheapter methods of gene delivery. A promising method is intravitreal injection, that does not cause retinal detachment, can lead to pan-retinal transduction and can be performed under local anesthesia in out-patient clinics. Intravitreally-injected vectors face several obstacles. First, the vector is diluted by the vitreous and has to overcome a long diffusion distance to the target cells. Second, the vector is exposed to the host's immune response, risking neutralization by pre-existing antibodies and triggering a stronger immune response to the injection. Third, the vector has to cross the inner limiting membrane which is both a physical and a biological barrier as it contains binding sites that could cause the vector's sequestration. Finally, in the target cell the vector is prone to proteasome degradation before delivering the transgene to the nucleus. Strategies to overcome these obstacles include modifications of the viral capsid, through rational design or directed evolution, which allow resistance to the immune system, enhancement of penetration through the inner limiting membrane or reduced degradation by intracellular proteasomes. Furthermore, physical and chemical manipulations of the inner limiting membrane and vitreous aim to improve vector penetration. Finally, compact non-viral vectors that can overcome the immunological, physical and anatomical and barriers have been developed. This paper reviews ongoing efforts to develop novel, safe and efficacious methods for intravitreal delivery of therapeutic genes for inherited retinal degenerations. To date, the most promising results are achieved in rodents with robust, pan-retinal transduction following intravitreal delivery. Trials in larger animal models demonstrate transduction mostly of inner retinal layers. Despite ongoing efforts, currently no intravitreally-injected vector has demonstrated outer retinal transduction efficacy comparable to that of subretinal delivery. Further work is warranted to test promising new viral and non-viral vectors on large animal models of inherited retinal degenerations. Positive results will pave the way to development of the next generation of treatments for inherited retinal degeneration.