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Keywords = cone-dystrophy

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12 pages, 2162 KB  
Case Report
Cone–Rod Dystrophy PCARE-Associated Retinopathy
by Maria Sopena-Pinilla, Maria Arruebo-Muñio, Marta Arias-Alvarez, Maria Arcas-Carbonell, Pablo Tejada-González, Carmen Lahuerta-Pueyo, Diana Pérez García and Isabel Pinilla
Diagnostics 2026, 16(13), 1945; https://doi.org/10.3390/diagnostics16131945 (registering DOI) - 23 Jun 2026
Viewed by 23
Abstract
Background and Clinical Significance: Biallelic pathogenic variants in the PCARE gene (photoreceptor cilium actin regulator), also known as C2orf71 (chromosome 2 open reading frame 71), are typically associated with retinitis pigmentosa type 54 (RP54) and, less frequently, with [...] Read more.
Background and Clinical Significance: Biallelic pathogenic variants in the PCARE gene (photoreceptor cilium actin regulator), also known as C2orf71 (chromosome 2 open reading frame 71), are typically associated with retinitis pigmentosa type 54 (RP54) and, less frequently, with cone–rod dystrophy (CORD23). Case Presentation: A 52-year-old man presented with an eight-year history of progressive visual loss, without photophobia or nyctalopia. He underwent a comprehensive ophthalmological evaluation, including multimodal retinal imaging, automated perimetry, and full electrophysiological testing, in accordance with International Society for Clinical Electrophysiology of Vision (ISCEV)’s standards. Genetic testing was performed using next-generation sequencing (NGS) with an inherited retinal dystrophy gene panel, and findings were confirmed by Sanger sequencing. Clinical examination revealed bilateral macular atrophy with minimal foveal sparing and a central scotoma. Optical coherence tomography (OCT) showed disruption of the outer retinal layers and retinal pigment epithelium (RPE) abnormalities. Fundus autofluorescence (FAF) demonstrated central hypoautofluorescence surrounded by a hyperautofluorescent ring. Electrophysiological testing revealed severely reduced rod- and cone- mediated responses on full-field electroretinography (ERG), absent pattern ERG responses, and markedly reduced multifocal ERG responses, indicating widespread retinal dysfunction with significant macular involvement. Genetic analysis identified a homozygous pathogenic nonsense variant in PCARE [c.3289C>T; p.(Gln1097*)], confirming the diagnosis of an autosomal recessive inherited retinal dystrophy. Conclusions: Biallelic PCARE variants can cause late-onset severe retinal dystrophy, with predominant macular involvement and cone–rod dysfunction. Given its phenotypic overlap with other inherited retinal diseases, accurate diagnosis requires the integration of multimodal retinal imaging, electrophysiological testing, and comprehensive genetic analysis. Full article
(This article belongs to the Section Clinical Diagnosis and Prognosis)
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24 pages, 1581 KB  
Article
Expanding the Mutation Spectrum of Non-Syndromic Retinitis Pigmentosa in Consanguineous Pakistani Families: Unraveling Novel Pathogenic Variants in RP1, PDE6B, and PRCD Genes for Precision Diagnosis
by Tayyaba Shan, Nimra Mukhtar, Sayyed Hammad Ullah, Asad Ullah, Asfandyar Ahmad Khan, Yumei Li, Meng Wang, Raeesa Tehreem, Amtul Aziz, Kiran Afshan, Rui Chen and Sabika Firasat
Genes 2026, 17(5), 529; https://doi.org/10.3390/genes17050529 - 29 Apr 2026
Viewed by 477
Abstract
Background: Non-syndromic retinitis pigmentosa (RP) is characterized by rod–cone degeneration, resulting in night blindness, visual field constriction, and eventual blindness. Recessively inherited RP is predominantly exacerbated in consanguineous populations, such as Pakistan. This study aimed to perform the genetic analysis of sixteen [...] Read more.
Background: Non-syndromic retinitis pigmentosa (RP) is characterized by rod–cone degeneration, resulting in night blindness, visual field constriction, and eventual blindness. Recessively inherited RP is predominantly exacerbated in consanguineous populations, such as Pakistan. This study aimed to perform the genetic analysis of sixteen non-syndromic RP segregating Pakistani families, and to summarize the mutation spectrum of non-syndromic RP in our population by reviewing related literature. Methods: We screened 16 non-syndromic RP families using targeted capture panel sequencing of 344 genes related to inherited retinal dystrophies. Variants were prioritized based on rarity (minor allele frequency (MAF) < 0.001 in the gnomAD South Asian subset), pathogenicity assessments using ACMG/AMP criteria, and REVEL scores (>0.5). Candidate variants were validated for familial segregation through Sanger sequencing. Results: We identified 15 distinct variants across 14 genes associated with non-syndromic retinitis pigmentosa, comprising 6 missense, 7 nonsense, 1 frameshift, and 2 splice-site variants, including 4 novel variants, i.e., p.(Val220Met) and p.(Pro1282SerfsTer2) in RP1, 1 each in PDE6B (c.2021+5G>A), and PRCD p.(Ser38Ter). Homozygosity predominated, underscoring the impact of consanguinity on the burden of autosomal recessive disease in the present cohort, while the CERKL disease-causing mutation, i.e., p.(Arg257Ter), recurred in two families. Conclusions: This study expands Pakistan’s non-syndromic RP mutational spectrum by identifying novel variants in RP1, PDE6B, and PRCD, alongside recurrent CERKL and RHO mutations of the local population. The literature review suggests that RP1, TULP1, and PDE6B are among the most mutated genes in our population, supporting the value of population-specific genetic panels to enhance diagnostics and carrier screening. Full article
(This article belongs to the Special Issue The Genetic Lens: A New Era in Ophthalmology)
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21 pages, 5097 KB  
Review
Prominin-1 and Retinal Degenerative Disorders: Expanding the Biology from Photoreceptors to the Retinal Pigment Epithelium
by Sujoy Bhattacharya, Caitlin Ang, Megan Soucy, Stephen H. Tsang and Edward Chaum
Biomolecules 2026, 16(5), 635; https://doi.org/10.3390/biom16050635 - 24 Apr 2026
Viewed by 894
Abstract
Prominin-1 (Prom1/CD133) has long been recognized as a structural determinant of photoreceptor outer segment (OS) morphogenesis, yet rapidly accumulating evidence extends its role to retinal pigment epithelium (RPE) homeostasis, encompassing autophagy–lysosomal flux, outer segment phagocytosis, mitochondrial function, and regulation of inflammatory [...] Read more.
Prominin-1 (Prom1/CD133) has long been recognized as a structural determinant of photoreceptor outer segment (OS) morphogenesis, yet rapidly accumulating evidence extends its role to retinal pigment epithelium (RPE) homeostasis, encompassing autophagy–lysosomal flux, outer segment phagocytosis, mitochondrial function, and regulation of inflammatory stress. This review synthesizes mechanistic and transcriptomic insights that position PROM1 as a central regulator of photoreceptor and RPE integrity, reframing Prom1 disease as a multi-compartment retinal disorder relevant to both inherited retinal dystrophies (IRDs) and atrophic age-related macular degeneration (aAMD). We develop a dual-axis conceptual model in which Prom1 dysfunction can initiate pathology in either the photoreceptors (OS morphogenesis failure) or the RPE, including impaired autophagic flux, lysosomal activity, defective phagocytosis, and Epithelial-Mesenchymal Transition (EMT)-like de-differentiation, with secondary cross-compartmental degeneration. Clinically, autosomal-dominant missense variants associate with macular or cone-rod dystrophy, whereas biallelic truncating/splice-site mutations drive early-onset rod–cone disease and panretinal/RPE atrophy, illustrating genotype–phenotype diversity. By integrating recent high-resolution transcriptomic data from Prom1-deficient RPE cells with long-standing insights into photoreceptor biology, we highlight converging pathways of degeneration that challenge a photoreceptor-centric view and unify disparate phenotypes within a single molecular framework. These insights broaden the therapeutic landscape, advancing gene augmentation and pathway-targeted strategies to preserve RPE integrity, sustain photoreceptor function, and modify disease course in PROM1-associated IRDs and atrophic AMD. Full article
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22 pages, 2702 KB  
Review
Gene-Agnostic Therapeutic Strategies for Inherited Retinal Diseases: Neuroprotection and Immunomodulation
by Lucas W. Rowe, S. Patricia Becerra, Robert E. MacLaren, Robert L. Avery, Charles C. Wykoff, Allen C. Ho, Carl D. Regillo, Dean Eliott, Andrew Osborne, Katie M. Binley and Thomas A. Ciulla
Genes 2026, 17(4), 392; https://doi.org/10.3390/genes17040392 - 30 Mar 2026
Viewed by 2072
Abstract
Background/Objectives: Inherited retinal diseases (IRDs) represent a genetically heterogeneous group of disorders caused by mutations in over 280 genes with more than 3100 identified variants. While gene-specific replacement therapies have achieved landmark success with voretigene neparvovec (Luxturna) for biallelic RPE65-associated retinal [...] Read more.
Background/Objectives: Inherited retinal diseases (IRDs) represent a genetically heterogeneous group of disorders caused by mutations in over 280 genes with more than 3100 identified variants. While gene-specific replacement therapies have achieved landmark success with voretigene neparvovec (Luxturna) for biallelic RPE65-associated retinal dystrophy, developing individual therapies for each genetic subtype remains impractical. This review examines gene-agnostic therapeutic approaches utilizing neuroprotection and immunomodulation that target common pathophysiological mechanisms shared across multiple IRD genotypes. Methods: We reviewed the literature on neuroprotective and immunomodulatory gene therapy strategies for IRDs, focusing on neurotrophic factors and complement system modulation. Results: Neuroprotective approaches delivering neurotrophic factors—including pigment epithelium-derived factor (PEDF), ciliary neurotrophic factor (CNTF), rod-derived cone viability factor (RdCVF), brain-derived neurotrophic factor (BDNF), fibroblast growth factors (FGFs), glial cell line-derived neurotrophic factor (GDNF), and proinsulin—have demonstrated photoreceptor preservation across multiple preclinical IRD models regardless of the underlying genetic mutation. The recent FDA approval of CNTF cell-based gene therapy (Encelto) for macular telangiectasia type 2 validates this therapeutic paradigm. Complement system inhibition represents another gene-agnostic strategy, with intravitreal complement inhibitors approved for geographic atrophy secondary to age-related macular degeneration and gene therapy approaches targeting C3, C5, or delivering soluble complement regulators under investigation for IRDs. Combination strategies simultaneously addressing multiple pathogenic pathways may offer synergistic benefits. Conclusions: Gene-agnostic approaches targeting neuroprotection and immunomodulation offer a therapeutic paradigm capable of benefiting patients across the spectrum of IRD genotypes, potentially transforming treatment for conditions where mutation-specific therapies remain unavailable. Full article
(This article belongs to the Section Human Genomics and Genetic Diseases)
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11 pages, 2071 KB  
Article
Heimler Syndrome Caused by Novel PEX6 Variants: Clinical and Genetic Characterization in a Saudi Cohort
by Basamat AlMoallem
Genes 2026, 17(4), 360; https://doi.org/10.3390/genes17040360 - 24 Mar 2026
Viewed by 624
Abstract
Background: Heimler syndrome (HS) is a rare autosomal recessive disorder representing the mildest end of the peroxisome biogenesis disorder spectrum. It is caused by hypomorphic mutations in peroxisomal assembly genes, most commonly PEX1 and PEX6, and is characterized by sensorineural hearing loss, [...] Read more.
Background: Heimler syndrome (HS) is a rare autosomal recessive disorder representing the mildest end of the peroxisome biogenesis disorder spectrum. It is caused by hypomorphic mutations in peroxisomal assembly genes, most commonly PEX1 and PEX6, and is characterized by sensorineural hearing loss, amelogenesis imperfecta, and retinal dystrophy. Due to phenotypic overlap with other inherited sensory disorders, particularly Usher syndrome, diagnosis of this condition is frequently delayed. Methods: We investigated two unrelated Saudi families presenting with congenital hearing loss and retinal dystrophy who were initially diagnosed with Usher syndrome. Detailed clinical evaluation, including comprehensive ophthalmologic and audiologic assessments, was performed. Whole-exome sequencing (WES) was conducted to identify the underlying genetic cause, followed by variant filtering and in silico pathogenicity prediction. Results: We identified a novel homozygous missense variant, p.Val97Gly (V97G), in the PEX6 gene that co-segregated with the disease phenotype in both families. This variant was absent from major population databases, including dbSNP, the 1000 Genomes Project, ExAC, and gnomAD, and was predicted to be deleterious by multiple in silico prediction tools. Clinically, affected individuals presented with congenital sensorineural hearing loss, pigmentary retinal dystrophy with electrophysiological evidence of cone–rod dysfunction, enamel abnormalities consistent with amelogenesis imperfecta, and mild dysmorphic facial features, supporting a diagnosis within the Heimler syndrome spectrum. Conclusions: Our findings expand the mutational spectrum of PEX6 and highlight Heimler syndrome as an important differential diagnosis in patients presenting with Usher-like phenotypes. To the best of our knowledge, this study represents the first report of the PEX6 p.Val97Gly variant associated with Heimler syndrome in a Saudi population, underscoring the value of whole-exome sequencing for accurate diagnosis and genetic counseling in individuals with inherited sensory disorders. Full article
(This article belongs to the Special Issue The Genetic Lens: A New Era in Ophthalmology)
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9 pages, 2586 KB  
Case Report
Systemic and Ocular Manifestations of a Ciliopathy: A Case Report of Renal–Retinal Involvement in Senior–Loken Syndrome
by Muzi Li, Siying Li, Yu Cao, Aimin Sun and Jinfeng Qu
J. Clin. Med. 2026, 15(5), 2060; https://doi.org/10.3390/jcm15052060 - 8 Mar 2026
Viewed by 482
Abstract
Background: Senior–Loken syndrome (SLS) is a rare autosomal recessive ciliopathy classically defined by the concurrence of nephronophthisis, frequently progressing to end-stage renal disease (ESRD), and retinal dystrophy, most commonly presenting as retinitis pigmentosa (RP). Given its phenotypic overlap with other renal–retinal syndromes, [...] Read more.
Background: Senior–Loken syndrome (SLS) is a rare autosomal recessive ciliopathy classically defined by the concurrence of nephronophthisis, frequently progressing to end-stage renal disease (ESRD), and retinal dystrophy, most commonly presenting as retinitis pigmentosa (RP). Given its phenotypic overlap with other renal–retinal syndromes, establishing a definitive diagnosis necessitates integrated clinical evaluation and molecular confirmation. Case Presentation: A 28-year-old Chinese female presented with a two-month history of binocular floaters. Her medical history was significant for ESRD of five years’ duration, managed with maintenance hemodialysis. Ophthalmic assessment revealed retinal pigment mottling along the inferior temporal arcades and generalized arterial attenuation. Spectral-domain optical coherence tomography demonstrated outer retinal thinning with loss of the ellipsoid zone at corresponding locations. Perimetry confirmed visual field constriction, and full-field electroretinography showed severely reduced rod- and cone-mediated responses. Genetic testing was performed and a pathogenic variant in the NPHP1 gene was identified. Segregation studies confirmed both parents as heterozygous carriers, consistent with autosomal recessive inheritance. Collectively, these findings established a diagnosis of SLS. Conclusions: This case reinforces that SLS should be considered in the differential diagnosis of any young patient exhibiting RP alongside chronic kidney disease, particularly in the setting of early-onset ESRD. It also illustrates the essential role of a coordinated, multidisciplinary approach—encompassing nephrology, ophthalmology, and genetics—in diagnosing complex ciliopathies. Genetic confirmation not only validates the clinical diagnosis but also provides a foundation for family counseling, prognostic stratification, and future eligibility for gene-specific therapeutic trials. Full article
(This article belongs to the Section Ophthalmology)
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22 pages, 1463 KB  
Article
Diagnostic Role of Chromatic Full-Field Stimulus Test in Rod–Cone Versus Cone Dystrophies
by Aykut Demirkol, Esra Sahli, Baichun Hou, Promie R. Faruque, Ilay Demirkol, Kuzey Soydas and Stephen H. Tsang
Biomedicines 2026, 14(2), 377; https://doi.org/10.3390/biomedicines14020377 - 6 Feb 2026
Viewed by 837
Abstract
Background: Inherited retinal dystrophies are a heterogeneous group of progressive disorders impacting photoreceptor function, often limiting the usefulness of standard electroretinography in advanced cases. Full-field stimulus test (FST) testing has become a sensitive psychophysical technique for detecting residual visual function when traditional electrophysiology [...] Read more.
Background: Inherited retinal dystrophies are a heterogeneous group of progressive disorders impacting photoreceptor function, often limiting the usefulness of standard electroretinography in advanced cases. Full-field stimulus test (FST) testing has become a sensitive psychophysical technique for detecting residual visual function when traditional electrophysiology is non-recordable. This study evaluated the ability of chromatic FST to differentiate rod–cone from cone photoreceptor dysfunction in patients with genetically confirmed inherited retinal dystrophies. Methods: Cross-sectional FST data were analyzed from 39 patients (mean age 45.7 ± 20.0 years) with genetically confirmed inherited retinal dystrophies at a tertiary academic center. All participants underwent standardized FST testing using white, red, and blue stimuli. Patients were classified into rod–cone dystrophy (n = 27) or cone dystrophy (n = 12) groups based on genetic and clinical criteria. Group comparisons focused on FST thresholds and especially blue–red threshold differences as markers of photoreceptor-mediated function. Bonferroni correction was applied to adjust for multiple comparisons across four primary FST parameters. Additional analyses by genotype were performed with nonparametric tests. Results: Eight different genetic mutations were represented, including Phosphodiesterase 6A (PDE6A) (n = 10), Rhodopsin (RHO) (n = 7), Phosphodiesterase 6B (PDE6B) (n = 6), Cyclic Nucleotide-Gated Channel Beta 1 (CNGB1) (n = 4), Cyclic Nucleotide-Gated Channel Alpha 3 (CNGA3) (n = 4), Nuclear Receptor Subfamily 2 Group E Member 3 (NR2E3) (n = 4), Guanylate Cyclase 2D (GUCY2D) (n = 2), and Cyclic Nucleotide-Gated Channel Beta 3 (CNGB3) (n = 2). Blue–red FST threshold differences exhibited moderate group discrimination in uncorrected analysis, with rod–cone dystrophies averaging −8.35 ± 10.37 dB and cone dystrophies −11.20 ± 14.60 dB. The area under the receiver operating characteristic curve for blue–red difference was 0.74 (95% CI: 0.59–0.90), with 75% sensitivity and 70.4% specificity at a −10 dB cutoff. However, no chromatic FST parameter maintained statistical significance between groups after Bonferroni correction. Inter-eye FST correlation was high (r = 0.758, p < 0.001), supporting test reliability. Conclusions: Chromatic FST testing provides a practical and sensitive means to assess photoreceptor function in advanced inherited retinal dystrophies, particularly when standard electrophysiologic methods are uninformative. Although the blue–red threshold difference offers moderate discrimination between rod–cone and cone dystrophies in uncorrected analysis, no chromatic parameter reached statistical significance after adjustment for multiple testing. Chromatic FST should be considered a supplementary approach for clinical monitoring and therapeutic studies in advanced retinal dystrophies, with further validation needed in larger cohorts. Full article
(This article belongs to the Section Molecular and Translational Medicine)
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14 pages, 1788 KB  
Article
CDHR1-Associated Retinal Dystrophies: Expanding the Clinical and Genetic Spectrum with a Hungarian Cohort
by Ágnes Takács, Balázs Varsányi, Mirella Barboni, Rita Vámos, Balázs Lesch, Dominik Dobos, Emília Clapp, András Végh, Ditta Zobor, Krisztina Knézy, Zoltán Zsolt Nagy and Viktória Szabó
Genes 2026, 17(1), 102; https://doi.org/10.3390/genes17010102 - 19 Jan 2026
Viewed by 1042
Abstract
Aim: To report on the clinical and genetic spectrum of retinopathy associated with CDHR1 variants in a Hungarian cohort. Methods: A retrospective cohort study was conducted at a single tertiary care referral center. The study enrolled nine patients harboring biallelic variants [...] Read more.
Aim: To report on the clinical and genetic spectrum of retinopathy associated with CDHR1 variants in a Hungarian cohort. Methods: A retrospective cohort study was conducted at a single tertiary care referral center. The study enrolled nine patients harboring biallelic variants in the CDHR1 gene. Detailed clinical history, multimodal imaging, electroretinography, and molecular genetics are presented. Results: We identified four CDHR1 variants predicted to cause loss-of-function and five phenotypes (cone dystrophy, central areolar choroidal dystrophy, cone-rod dystrophy, rod-cone dystrophy, and late-onset macular dystrophy). The most frequent variant was the synonymous CDHR1 c.783G>A (p.Pro261=) variant (10/18 alleles, 55.6%). A novel splice acceptor site variant, CDHR1 c.349-1G>A, and a novel intronic variant, CDHR1 c.1168-10A>G, were also detected. Fundus examination revealed macular atrophy with or without peripheral retinal changes. Full-field electroretinography, available in seven patients, demonstrated decreased light-adapted and extinguished dark-adapted responses in both the rod-cone dystrophy group and patients with macular involvement. OCT imaging indicated ellipsoid zone disruption with foveal sparing in two out of nine patients and severe retinal damage in rod-cone dystrophy cases. Conclusions: The predominant clinical manifestations of cone dystrophy, cone-rod dystrophy, and macular dystrophy in the Hungarian patient cohort showed heterogeneity, with a rod-cone dystrophy phenotype observed in five of nine cases (55.6%). The natural history of CDHR1-associated retinopathy typically follows a slow progression, providing a therapeutic window, which makes the disease a candidate for gene therapy. Full article
(This article belongs to the Special Issue Current Advances in Inherited Retinal Disease)
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12 pages, 2039 KB  
Article
Nasal Retinal Degeneration Is a Feature of a Subset of CRX-Associated Retinopathies
by Michael T. Massengill, Tamara Juvier Riesgo, Janet L. Davis, Carlos E. Mendoza-Santiesteban, Brian E. Goldhagen, Byron L. Lam and Ninel Z. Gregori
Genes 2026, 17(1), 50; https://doi.org/10.3390/genes17010050 - 1 Jan 2026
Viewed by 827
Abstract
Background/Objectives: Genetic variants in the cone–rod homeobox (CRX) gene, a transcription factor critical for the differentiation, function, and survival of photoreceptors, are a rare cause of inherited retinal diseases (IRDs). CRX-associated retinopathies can produce variable phenotypes, including Leber congenital [...] Read more.
Background/Objectives: Genetic variants in the cone–rod homeobox (CRX) gene, a transcription factor critical for the differentiation, function, and survival of photoreceptors, are a rare cause of inherited retinal diseases (IRDs). CRX-associated retinopathies can produce variable phenotypes, including Leber congenital amaurosis (LCA), maculopathy (M), cone-rod dystrophy (CRD), and rod-cone dystrophy (RCD), such as retinitis pigmentosa (RP). Based on clinical observations at our eye institute, we hypothesized that nasal retinal degeneration is a feature of CRX-associated maculopathy and M/CRD. Methods: We performed an IRB-approved, retrospective review of patients at our eye institute with CRX-associated retinopathy to assess the frequency of nasal degeneration and potential genotype–phenotype correlations. Results: A total of 15 patients with a CRX-associated retinopathy and meeting the inclusion criteria were identified (LCA 3, RCD/RP 2, M/CRD 10). Overall, nasal degeneration occurred in 8 of 15 patients (53.3%) in the cohort. Nasal retinal degeneration was seen in the M/CRD (6 of 10; 60.0%) as well as LCA groups (2 of 3; 66.6%). No significant differences in age, gender, or presenting visual acuity were observed between patients with and without nasal degeneration. Genetic variants associated with nasal degeneration are localized to both the homeobox motif and activation domain. Intronic variants were relatively more common in patients with nasal degeneration, while missense variants predominated in those without, although these differences were not statistically significant. Conclusions: We conclude that nasal degeneration is a feature of a subset of CRX-associated phenotypes, affects both genders, and can be caused by genetic variants in multiple locations and of various subtypes. Full article
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22 pages, 5106 KB  
Article
KCNV2-Deficient Retinal Organoid Model of Cone Dystrophy—In Vitro Screening for AAV Gene Replacement Therapy
by Sophie L. Busson, Arifa Naeem, Silvia Ferrara, Shilpita Sarcar, Toyin Adefila-Ideozu, Sarah Wells, Sophia El Alami, James Boot, Paul E. Sladen, Michel Michaelides, Anastasios Georgiadis and Amelia Lane
Int. J. Mol. Sci. 2026, 27(1), 449; https://doi.org/10.3390/ijms27010449 - 31 Dec 2025
Cited by 1 | Viewed by 1332
Abstract
KCNV2 encodes Kv8.2, an electrically silent voltage-gated potassium channel subunit that is expressed in photoreceptors. Disease-causing variants in KCNV2 cause a monogenic disorder which is classified clinically as cone dystrophy with supernormal rod response (CDSRR). Here, we generated KCNV2-deficient human retinal organoids [...] Read more.
KCNV2 encodes Kv8.2, an electrically silent voltage-gated potassium channel subunit that is expressed in photoreceptors. Disease-causing variants in KCNV2 cause a monogenic disorder which is classified clinically as cone dystrophy with supernormal rod response (CDSRR). Here, we generated KCNV2-deficient human retinal organoids as a tool for gene therapy vector potency assessment. The organoids were derived from two separate sources: by generating IPSCs from patient blood and by gene editing of a control cell line. Eight KCNV2 gene therapy vectors were assessed in retinal organoids; Kv8.2 protein levels and its in situ interactions with potassium channel binding partners were quantitatively assessed. We show significant enhancements in vector potency and specificity by transgene codon optimisation and the use of the photoreceptor-specific rhodopsin kinase (RK) promoter, respectively. Single-cell RNA sequencing was performed in transduced retinal organoids to assess the performance of the AAV vectors at single-cell resolution. KCNV2-deficient photoreceptors had an upregulation in genes associated with apoptosis, oxidative stress, and hypoxia pathways which were partially restored in AAV-KCNV2 transduced photoreceptors. These data show how human retinal organoids can be used to evaluate AAV gene therapy vector potency in vitro in a physiologically relevant model for the selection of lead therapeutic candidates and to help minimise the use of animals in preclinical development. Full article
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19 pages, 3471 KB  
Article
The Specific Pathogenicity Pattern of the Different CRB1 Isoforms Conditions Clinical Severity in Inherited Retinal Dystrophies
by Laura Siles, Sheila Ruiz-Nogales, Pilar Méndez-Vendrell, Anniken Burés-Jelstrup, Rafael Navarro and Esther Pomares
Int. J. Mol. Sci. 2025, 26(23), 11551; https://doi.org/10.3390/ijms262311551 - 28 Nov 2025
Cited by 1 | Viewed by 882
Abstract
Pathogenic variants in Crumbs homolog 1 (CRB1) cause a wide range of severe ocular diseases, most commonly Leber congenital amaurosis and other forms of adult-onset macular dystrophy that lead to vision loss. Despite this broad clinical spectrum, the expression and function [...] Read more.
Pathogenic variants in Crumbs homolog 1 (CRB1) cause a wide range of severe ocular diseases, most commonly Leber congenital amaurosis and other forms of adult-onset macular dystrophy that lead to vision loss. Despite this broad clinical spectrum, the expression and function of CRB1 in retinal cells remains underexplored. In this study, we show a comprehensive characterization of CRB1 isoforms in several human retinal models like retinal organoids. Although CRB1 is predominantly expressed in photoreceptors and Müller glial cells, we also detected its expression in the human retinal pigment epithelium (RPE). Moreover, we observed defined expression patterns of CRB1 isoforms depending on the maturation stage of retinal cells, suggesting a role for this protein in development and differentiation. In this context, the less abundant and less studied isoform CRB1-C was the most highly expressed in early undifferentiated stages of photoreceptors and in RPE. Additionally, clinical and genetic evaluation of a cohort of 25 probands carrying pathogenic CRB1 variants allowed us to propose a genotype–phenotype correlation between isoforms involvement and disease severity, and to the identification of four novel pathogenic variants: p.Met70ArgfsTer17, p.Cys136Phe, p.Cys248Ser and p.Gln1094Ter. Collectively, our data elucidate previously undescribed expression patterns of CRB1 isoforms during retinal cell differentiation and highlight key aspects of CRB1-associated inherited retinal dystrophies. Full article
(This article belongs to the Special Issue Advances in Retinal Diseases: 2nd Edition)
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11 pages, 2253 KB  
Case Report
Longitudinal Multimodal Assessment of Structure and Function in INPP5E-Related Retinopathy
by Andrea Cusumano, Marco Lombardo, Benedetto Falsini, Michele D’Ambrosio, Jacopo Sebastiani, Enrica Marchionni, Maria Rosaria D’Apice, Barbara Rizzacasa, Francesco Martelli and Giuseppe Novelli
Genes 2025, 16(12), 1407; https://doi.org/10.3390/genes16121407 - 26 Nov 2025
Cited by 1 | Viewed by 650
Abstract
Background: INPP5E-related retinopathy (INPP5E-RR) is a rare genetic disorder caused by biallelic pathogenic variants in the INPP5E gene, which encodes an enzyme critical for phosphoinositide signaling. While early-onset rod–cone dystrophy is a hallmark feature, detailed longitudinal data on the [...] Read more.
Background: INPP5E-related retinopathy (INPP5E-RR) is a rare genetic disorder caused by biallelic pathogenic variants in the INPP5E gene, which encodes an enzyme critical for phosphoinositide signaling. While early-onset rod–cone dystrophy is a hallmark feature, detailed longitudinal data on the phenotype are scarce. This study aims to report a 6-year longitudinal assessment of retinal structure and function in a case of non-syndromic INPP5E-RR. Methods: A 42-year-old female proband with compound heterozygous pathogenic missense variants in INPP5E (p.Arg486Cys and p.Arg378Cys) was monitored from 2019 to 2025. She underwent serial comprehensive ophthalmologic evaluations, including optical coherence tomography (OCT), fundus autofluorescence, adaptive optics transscleral flood illumination, full-field 30Hz flicker electroretinography (ERG), and macular frequency-doubling technology perimetry. Results: Over the 6-year follow-up, OCT imaging revealed a progressive decline in the ellipsoid zone (EZ) width, from 1220 µm to 720 µm (~80 µm/year), and in the inner nuclear layer (INL) thickness. The central outer nuclear layer (ONL) thickness was preserved, but intraretinal cysts developed. Functional testing revealed a progressive decline in cone flicker ERG amplitudes, while visual acuity and macular perimetry remained stable. Conclusions: In this genotypically confirmed case, the longitudinal data identify EZ width, INL thickness, and cone flicker ERG as robust biomarkers of disease progression in INPP5E-RR. These parameters are ideal candidates for monitoring therapeutic outcomes in future clinical trials. Full article
(This article belongs to the Special Issue Current Advances in Inherited Retinal Disease)
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16 pages, 3190 KB  
Case Report
Retinal Function Deficits in American Staffordshire Terriers with a Late-Onset Neurodegenerative Disease Associated with an ARSG Variant
by Grace R. Kick, Samantha L. Marzano, Juri Ota-Kuroki, Garrett Bullock and Martin L. Katz
Vet. Sci. 2025, 12(11), 1078; https://doi.org/10.3390/vetsci12111078 - 12 Nov 2025
Viewed by 742
Abstract
American Staffordshire Terriers (ASTs) with a c.296G>A variant in ARSG develop progressive ataxia, cerebellar atrophy, and neuronal accumulation of autofluorescent storage material. Human subjects with ARSG variants exhibit hearing loss and rod–cone dystrophy without apparent other neurological involvement and arsg knockout mice exhibit [...] Read more.
American Staffordshire Terriers (ASTs) with a c.296G>A variant in ARSG develop progressive ataxia, cerebellar atrophy, and neuronal accumulation of autofluorescent storage material. Human subjects with ARSG variants exhibit hearing loss and rod–cone dystrophy without apparent other neurological involvement and arsg knockout mice exhibit progressive ataxia, lysosomal storage, and photoreceptor loss. Owners of 8 of 11 affected ASTs evaluated for the ARSG risk variant reported observing visual impairment in their dogs, suggesting that the canine disease may involve retinal dysfunction consistent with human subjects and mice with ARSG variants. To assess whether this might be the case, electroretinography was performed on four affected and three unaffected ASTs. Three affected dogs that were exhibiting signs of ataxia had attenuated electroretinogram (ERG) amplitudes indicative of rod and cone photoreceptor dysfunction, while ERG responses were not attenuated in a younger dog that had not yet shown signs of ataxia or visual impairment. Autofluorescent inclusions were observed in the retinal pigment epithelium and retinal ganglion cell layer of two affected dogs that were euthanized due to neurological disease progression. The results from these cases indicate that standardized electroretinography can be used to detect retinal dysfunction in dogs with the ARSG-related disorder and in other disorders in which dogs exhibit apparent impairment in visually mediated behavior. Full article
(This article belongs to the Section Veterinary Internal Medicine)
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13 pages, 254 KB  
Article
Patient-Reported Social Impact of Molecularly Confirmed Macular Dystrophies and Cone–Rod Dystrophies
by Nina Zehe-Lindau, Birgit Lindau, Heidi Stöhr, Bernhard H. F. Weber, Georg Spital and Ulrich Kellner
J. Clin. Med. 2025, 14(22), 7928; https://doi.org/10.3390/jcm14227928 - 8 Nov 2025
Viewed by 628
Abstract
Objectives: To identify patient-reported key disease-related challenges of macular and cone–rod dystrophies (MDs/CRDs) in a large consecutive cohort of individuals with molecularly confirmed diagnoses. Methods: Out of the 281 patients contacted, 194 (69.0%; 55.2% female) responded to an anonymized survey exploring the effects [...] Read more.
Objectives: To identify patient-reported key disease-related challenges of macular and cone–rod dystrophies (MDs/CRDs) in a large consecutive cohort of individuals with molecularly confirmed diagnoses. Methods: Out of the 281 patients contacted, 194 (69.0%; 55.2% female) responded to an anonymized survey exploring the effects of MD/CRD on vocational training, professional careers, social participation, family life, personal well-being, and experience with ophthalmologic care. Results: While vocational training was generally less affected, professional careers were frequently disrupted, with 20.6% of patients aged ≥ 50 retiring early. A majority (54.7%) reported feeling restricted in public life. Financial constraints were noted by 20%. A negative impact on familial life (12.3%) was less frequently reported compared to anxiety (74.2%) and depression (15.8%). Diagnostic delays (≥2 years) were common (34.2%), along with a notable rate of initial misdiagnoses (22.1%). The lack of adequate psychological support was a major complaint in professional care. Conclusions: Compared to a previous study in retinitis pigmentosa, MD/CRD patients reported differing patterns of burden, especially in early retirement and family impact. Our findings underscore the need for ophthalmic and social care providers to accelerate the diagnostic process and enhance access to financial assistance and psychological support as key areas to improve patient care. Full article
9 pages, 1574 KB  
Article
Clinical and Molecular Findings in PROM1-Associated Inherited Retinal Dystrophies
by Fabiana D’Esposito, Caterina Gagliano, Sabrina Vallone, Francesco Cappellani, Giuseppe Gagliano, Viviana Randazzo, Daniele Tognetto, Gabriella Esposito and Marco Zeppieri
Genes 2025, 16(11), 1299; https://doi.org/10.3390/genes16111299 - 1 Nov 2025
Cited by 1 | Viewed by 1288
Abstract
Background: Inherited retinal dystrophies (IRDs) include a clinically and genetically diverse array of conditions resulting in progressive visual impairment. The PROM1 gene is crucial for the development and maintenance of photoreceptors. Variants in PROM1 are linked to a wide phenotypic spectra of IRDs; [...] Read more.
Background: Inherited retinal dystrophies (IRDs) include a clinically and genetically diverse array of conditions resulting in progressive visual impairment. The PROM1 gene is crucial for the development and maintenance of photoreceptors. Variants in PROM1 are linked to a wide phenotypic spectra of IRDs; however, the correlation between genotype and phenotype is not fully elucidated. Comprehending these relationships is essential for enhanced diagnostic precision, patient guidance, and formulation of focused treatments. Objective: This study aims to examine the genotype–phenotype associations in patients with PROM1-associated IRDs. Clinical variability and inheritance patterns linked to different pathogenic variants are examined, aiming to clarify their different behaviors. Methods: We performed a retrospective investigation of patients identified as affected by PROM1-related IRDs. Thorough ophthalmologic assessments, including retinography, fundus autofluorescence, optical coherence tomography (OCT), and electrodiagnostic testing (EDT), were conducted. Genetic testing was performed via targeted gene panels or whole-exome sequencing. Variants were categorized based on ACMG criteria, and inheritance patterns were determined by familial segregation analysis. Clinical characteristics were analyzed among genotypic groups to ascertain potential phenotype–genotype relationships. Results: All patients had pathogenic or likely pathogenic PROM1 mutations. Both autosomal dominant and autosomal recessive inheritance patterns were identified. Dominant pathogenic variants were predominantly linked to late-onset cone-rod dystrophy or macular dystrophy, whereas biallelic variants frequently resulted in early-onset severe rod–cone dystrophy characterized by fast vision deterioration. A group of patients with the same genotypes displayed significant phenotypic variability, indicating the potential impact of modifier genes or environmental influences. Truncating mutations in the N-terminal region were significantly associated with earlier illness onset and greater functional impairment. Conclusions: PROM1-related IRDs demonstrated significant clinical and genetic heterogeneity, with the route of inheritance and type of variant affecting disease severity and progression. Our findings underscore the significance of thorough genotypic and phenotypic characterization in afflicted individuals. A deeper comprehension of PROM1-related IRD disease pathways can enhance prognosis, direct clinical care, and facilitate the advancement of genotype-based therapy strategies. Full article
(This article belongs to the Special Issue Current Advances in Inherited Retinal Disease)
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