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Rao NT, Sumaroka A, Santos AJ, Parchinski KM, Weber ML, Maguire AM, Cideciyan AV, Aleman TS. Detailed phenotype and long-term follow-up of RAB28-associated cone-rod dystrophy. Ophthalmic Genet 2024:1-10. [PMID: 38956823 DOI: 10.1080/13816810.2024.2362204] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2024] [Accepted: 05/27/2024] [Indexed: 07/04/2024]
Abstract
PURPOSE To gain an insight into the pathophysiology of RAB28-associated inherited retinal degeneration through detailed phenotyping and long-term longitudinal follow-up. METHODS The patient underwent complete ophthalmic examinations. Visual function was assessed with microperimetry, full-field electroretinography (ffERG), imaging with optical coherence tomography (OCT), short-wave (SW), and near-infrared (NIR) fundus autofluorescence (FAF). RESULTS A healthy Haitian woman with homozygous pathogenic variants (c.68C > T; p.Ser23Phe) in RAB28 presented at 16 years of age with a four-year history of blurred vision. Visual acuities were 20/125 in each eye, which remained relatively stable since. At age 27, cone ffERGs were non-detectable and borderline for rod-mediated responses. Kinetic fields were full to a V-4e target, undetectable to a small I-4e stimulus. Microperimetry showed an absolute central scotoma surrounded by a pericentral relative scotoma. SD-OCT showed an undetectable or barely detectable foveal and parafoveal photoreceptor outer nuclear layer (ONL), photoreceptor outer segment (POS), and retinal pigment epithelium (RPE) signals and loss of the SW- and NIR-FAF signals. This atrophic region was separated from a normally laminated retina by a narrow transition zone (TZ) of hyper SW- and NIR-FAF that co-localized with preserved ONL but abnormally thinned POS and RPE. There was minimal centrifugal (<100 μ m) expansion over a six-year period. CONCLUSION The cone-rod dystrophy phenotype documented herein supports a critical role of RAB28 for cone function and POS maintenance. Severe central photoreceptor and RPE loss with a predilection for POS loss in TZs suggests possible disruptions of complex mechanisms that maintain central cone photoreceptor and RPE homeostasis.
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Affiliation(s)
- Nitya T Rao
- Department of Ophthalmology, Scheie Eye Institute, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Alexander Sumaroka
- Department of Ophthalmology, Scheie Eye Institute, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Arlene J Santos
- Department of Ophthalmology, Scheie Eye Institute, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Kelsey M Parchinski
- Department of Ophthalmology, Scheie Eye Institute, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Mariejel L Weber
- Department of Ophthalmology, Scheie Eye Institute, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Albert M Maguire
- Department of Ophthalmology, Scheie Eye Institute, University of Pennsylvania, Philadelphia, Pennsylvania, USA
- Division of Ophthalmology, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
| | - Artur V Cideciyan
- Department of Ophthalmology, Scheie Eye Institute, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Tomas S Aleman
- Department of Ophthalmology, Scheie Eye Institute, University of Pennsylvania, Philadelphia, Pennsylvania, USA
- Division of Ophthalmology, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
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2
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Huang WC, Ohnsman CM, Atiskova Y, Falabella P, Spitzer MS, Schulz A, Dulz S. OCT Biomarkers in Ocular CLN2 Disease in Patients Treated With Intraventricular Enzyme Replacement Therapy. Invest Ophthalmol Vis Sci 2024; 65:45. [PMID: 39078732 PMCID: PMC11290571 DOI: 10.1167/iovs.65.8.45] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2023] [Accepted: 04/27/2024] [Indexed: 08/02/2024] Open
Abstract
Purpose Bilateral progressive, symmetrical loss of central retinal thickness (CRT) has been described in neuronal ceroid lipofuscinosis type 2 (CLN2) disease. This study details the pattern of morphological changes underlying CRT loss and disease progression in patients receiving intracerebroventricular (ICV) enzyme replacement therapy (ERT) with cerliponase alfa. Methods Spectral-domain optical coherence tomography macular cube scans were collected from 16 patients with classic CLN2 disease receiving ICV ERT. Detailed retinal structure analyses were performed on manually segmented horizontal B-scans through the fovea to determine the thickness of six retinal parameters and the extent of ellipsoid zone (EZ) loss. Results Anatomical changes primarily occurred in photoreceptor (PR)-related retinal parameters and correlated with ocular disease severity. Retinal degeneration began with initial focal parafoveal EZ discontinuities signaling the onset of rapid PR degeneration in a predictable pattern: parafoveal PR involvement with foveal sparing followed by profound parafoveal and foveal PR loss with additional thinning beyond the central retina. PR degeneration began with outer segment loss and progressed to outer nuclear layer (ONL) involvement. Longitudinal analyses confirmed these observations. The rate of PR loss was fastest at the fovea at ∼58 mm per year and became slower at locations farther away from the fovea. Conclusions Retinal degeneration in CLN2 disease is primarily associated with PR loss in a predictable pattern, with EZ disruption signaling early PR stress. CRT, ONL thickness, and PR layer thickness are useful anatomical biomarkers for understanding disease progression and treatment efficacy in CLN2. Studies using en face images will further clarify CLN2-related retinal degeneration.
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Affiliation(s)
| | | | | | | | | | - Angela Schulz
- Children's Hospital, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
- German Center for Child and Adolescent Health (DZKJ), partner site Hamburg, Hamburg, Germany
| | - Simon Dulz
- University Medical Center Hamburg-Eppendorf, Hamburg, Germany
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3
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Gwack J, Kim N, Park J. Improving the Yield of Genetic Diagnosis through Additional Genetic Panel Testing in Hereditary Ophthalmic Diseases. Curr Issues Mol Biol 2024; 46:5010-5022. [PMID: 38785568 PMCID: PMC11119902 DOI: 10.3390/cimb46050300] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2024] [Revised: 05/17/2024] [Accepted: 05/18/2024] [Indexed: 05/25/2024] Open
Abstract
Numerous hereditary ophthalmic diseases display significant genetic diversity. Consequently, the utilization of gene panel sequencing allows a greater number of patients to receive a genetic diagnosis for their clinical manifestations. We investigated how to improve the yield of genetic diagnosis through additional gene panel sequencing in hereditary ophthalmic diseases. A gene panel sequencing consisting of a customized hereditary retinopathy panel or hereditary retinitis pigmentosa (RP) panel was prescribed and referred to a CAP-accredited clinical laboratory. If no significant mutations associated with hereditary retinopathy and RP were detected in either panel, additional gene panel sequencing was requested for research use, utilizing the remaining panel. After additional gene panel sequencing, a total of 16 heterozygous or homozygous variants were identified in 15 different genes associated with hereditary ophthalmic diseases. Of 15 patients carrying any candidate variants, the clinical symptoms could be tentatively accounted for by genetic mutations in seven patients. However, in the remaining eight patients, given the in silico mutation predictive analysis, variant allele frequency in gnomAD, inheritance pattern, and genotype-phenotype correlation, fully elucidating the clinical manifestations with the identified rare variant was challenging. Our study highlights the utility of gene panel sequencing in achieving accurate diagnoses for hereditary ophthalmic diseases and enhancing the diagnostic yield through additional gene panel sequencing. Thus, gene panel sequencing can serve as a primary tool for the genetic diagnosis of hereditary ophthalmic diseases, even in cases where a single genetic cause is suspected. With a deeper comprehension of the genetic mechanisms underlying these diseases, it becomes feasible.
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Affiliation(s)
- Jin Gwack
- Department of Preventive Medicine, Jeonbuk National University Medical School, Jeonju 54907, Republic of Korea;
| | - Namsu Kim
- Department of Laboratory Medicine, Jeonbuk National University Medical School and Hospital, Jeonju 54907, Republic of Korea;
- Research Institute of Clinical Medicine of Jeonbuk National University-Biomedical Research Institute of Jeonbuk National University Hospital, Jeonju 54907, Republic of Korea
| | - Joonhong Park
- Department of Laboratory Medicine, Jeonbuk National University Medical School and Hospital, Jeonju 54907, Republic of Korea;
- Research Institute of Clinical Medicine of Jeonbuk National University-Biomedical Research Institute of Jeonbuk National University Hospital, Jeonju 54907, Republic of Korea
- Department of Laboratory Medicine, Daejeon St. Mary’s Hospital, Daejeon 34943, Republic of Korea
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4
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Esteve-Garcia A, Cobos E, Sau C, Padró-Miquel A, Català-Mora J, Barberán-Martínez P, Millán JM, García-García G, Aguilera C. Deciphering complexity: TULP1 variants linked to an atypical retinal dystrophy phenotype. Front Genet 2024; 15:1352063. [PMID: 38450199 PMCID: PMC10915255 DOI: 10.3389/fgene.2024.1352063] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2023] [Accepted: 01/29/2024] [Indexed: 03/08/2024] Open
Abstract
Introduction: TULP1 exemplifies the remarkable clinical and genetic heterogeneity observed in inherited retinal dystrophies. Our research describes the clinical and molecular characteristics of a patient manifesting an atypical retinal dystrophy pattern, marked by the identification of both a previously unreported and a rarely encountered TULP1 variant. Methods: Whole-exome sequencing was performed to identify potential causative variants. The pathogenicity of the identified TULP1 variants was evaluated through in silico predictors and a minigene splice assay, specifically designed to assess the effect of the unreported TULP1 variant. Results: We identified two TULP1 gene variants in a patient exhibiting unusual and symmetrical alterations in both retinas, characterized by an increase in autofluorescence along the distribution of retinal vessels. These variants included a known rare missense variant, c.1376T>C, and a novel splice site variant, c.822G>T. For the latter variant (c.822G>T), we conducted a minigene splice assay that demonstrated the incorporation of a premature stop codon. This finding suggests a likely activation of the nonsense-mediated mRNA decay mechanism, ultimately resulting in the absence of protein production from this allele. Segregation analysis confirmed that these variants were in trans. Discussion: Our data support that individuals with biallelic TULP1 variants may present with a unique pattern of macular degeneration and periarteriolar vascular pigmentation. This study highlights the importance of further clinical and molecular characterization of TULP1 variants to elucidate genotype-phenotype correlations in the context of inherited retinal dystrophies.
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Affiliation(s)
- Anna Esteve-Garcia
- Department of Clinical Genetics, Bellvitge University Hospital, Institut d’Investigació Biomèdica de Bellvitge (IDIBELL), L'Hospitalet de Llobregat, Barcelona, Spain
| | - Estefania Cobos
- Department of Ophthalmology, Bellvitge University Hospital, Institut d’Investigació Biomèdica de Bellvitge (IDIBELL), L'Hospitalet de Llobregat, Barcelona, Spain
| | - Cristina Sau
- Department of Clinical Genetics, Bellvitge University Hospital, Institut d’Investigació Biomèdica de Bellvitge (IDIBELL), L'Hospitalet de Llobregat, Barcelona, Spain
| | - Ariadna Padró-Miquel
- Genetics Laboratory, Bellvitge University Hospital, Institut d’Investigació Biomèdica de Bellvitge (IDIBELL), L'Hospitalet de Llobregat, Barcelona, Spain
| | - Jaume Català-Mora
- Department of Ophthalmology, SJD Barcelona Children’s Hospital, Barcelona, Spain
| | - Pilar Barberán-Martínez
- Molecular, Cellular, and Genomic Biomedicine Group, Valencia, Spain
- Joint Unit CIPF-IIS La Fe Molecular, Cellular and Genomic Biomedicine, Valencia, Spain
| | - José M. Millán
- Molecular, Cellular, and Genomic Biomedicine Group, Valencia, Spain
- Joint Unit CIPF-IIS La Fe Molecular, Cellular and Genomic Biomedicine, Valencia, Spain
- Center for Rare Diseases (CIBERER), Madrid, Spain
- University and Polytechnic La Fe Hospital of Valencia, Valencia, Spain
| | - Gema García-García
- Molecular, Cellular, and Genomic Biomedicine Group, Valencia, Spain
- Joint Unit CIPF-IIS La Fe Molecular, Cellular and Genomic Biomedicine, Valencia, Spain
- Center for Rare Diseases (CIBERER), Madrid, Spain
| | - Cinthia Aguilera
- Genetics Laboratory, Bellvitge University Hospital, Institut d’Investigació Biomèdica de Bellvitge (IDIBELL), L'Hospitalet de Llobregat, Barcelona, Spain
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Ashourizadeh H, Fakhri M, Hassanpour K, Masoudi A, Jalali S, Roshandel D, Chen FK. Pearls and Pitfalls of Adaptive Optics Ophthalmoscopy in Inherited Retinal Diseases. Diagnostics (Basel) 2023; 13:2413. [PMID: 37510157 PMCID: PMC10377978 DOI: 10.3390/diagnostics13142413] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Revised: 07/12/2023] [Accepted: 07/18/2023] [Indexed: 07/30/2023] Open
Abstract
Adaptive optics (AO) retinal imaging enables individual photoreceptors to be visualized in the clinical setting. AO imaging can be a powerful clinical tool for detecting photoreceptor degeneration at a cellular level that might be overlooked through conventional structural assessments, such as spectral-domain optical coherence tomography (SD-OCT). Therefore, AO imaging has gained significant interest in the study of photoreceptor degeneration, one of the most common causes of inherited blindness. Growing evidence supports that AO imaging may be useful for diagnosing early-stage retinal dystrophy before it becomes apparent on fundus examination or conventional retinal imaging. In addition, serial AO imaging may detect structural disease progression in early-stage disease over a shorter period compared to SD-OCT. Although AO imaging is gaining popularity as a structural endpoint in clinical trials, the results should be interpreted with caution due to several pitfalls, including the lack of standardized imaging and image analysis protocols, frequent ocular comorbidities that affect image quality, and significant interindividual variation of normal values. Herein, we summarize the current state-of-the-art AO imaging and review its potential applications, limitations, and pitfalls in patients with inherited retinal diseases.
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Affiliation(s)
| | - Maryam Fakhri
- Ophthalmic Research Center, Research Institute for Ophthalmology and Vision Sciences, Shahid Beheshti University of Medical Sciences, Tehran 16666, Iran
| | - Kiana Hassanpour
- Ophthalmic Research Center, Research Institute for Ophthalmology and Vision Sciences, Shahid Beheshti University of Medical Sciences, Tehran 16666, Iran
| | - Ali Masoudi
- Stein Eye Institute, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
| | - Sattar Jalali
- Department of Physics, Central Tehran Branch, Islamic Azad University, Tehran 19558, Iran
| | - Danial Roshandel
- Centre for Ophthalmology and Visual Science, The University of Western Australia, Nedlands, WA 6009, Australia
- Ocular Tissue Engineering Laboratory, Lions Eye Institute, Nedlands, WA 6009, Australia
| | - Fred K Chen
- Centre for Ophthalmology and Visual Science, The University of Western Australia, Nedlands, WA 6009, Australia
- Ocular Tissue Engineering Laboratory, Lions Eye Institute, Nedlands, WA 6009, Australia
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, Melbourne, VIC 3002, Australia
- Ophthalmology, Department of Surgery, University of Melbourne, Melbourne, VIC 3010, Australia
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6
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Majander A, Sankila EM, Falck A, Vasara LK, Seitsonen S, Kulmala M, Haavisto AK, Avela K, Turunen JA. Natural history and biomarkers of retinal dystrophy caused by the biallelic TULP1 variant c.148delG. Acta Ophthalmol 2023; 101:215-221. [PMID: 36128853 DOI: 10.1111/aos.15252] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2022] [Revised: 08/19/2022] [Accepted: 09/03/2022] [Indexed: 11/27/2022]
Abstract
PURPOSE To report clinical features and potential disease markers of inherited retinal dystrophy (IRD) caused by the biallelic c.148delG variant in the tubby-like protein 1 (TULP1) gene. METHODS A retrospective observational study of 16 IRD patients carrying a homozygous pathogenic TULP1 c.148delG variant. Clinical data including fundus spectral-domain optical coherence tomography (SD-OCT) were assessed. A meta-analysis of visual acuity of previously reported other pathogenic TULP1 variants was performed for reference. RESULTS The biallelic TULP1 variant c.148delG was associated with infantile and early childhood onset IRD. Retinal ophthalmoscopy was primarily normal converting to peripheral pigmentary retinopathy and maculopathy characterized by progressive extra-foveal loss of the ellipsoid zone (EZ), the outer plexiform layer (OPL), and the outer nuclear layer (ONL) bands in the SD-OCT images. The horizontal width of the foveal EZ showed significant regression with the best-corrected visual acuity (BCVA) of the eye (p < 0.0001, R2 = 0.541, F = 26.0), the age of the patient (p < 0.0001, R2 = 0.433, F = 16.8), and mild correlation with the foveal OPL-ONL thickness (p = 0.014, R2 = 0.245, F = 7.2). Modelling of the BCVA data suggested a mean annual loss of logMAR 0.027. The level of visual loss was similar to that previously reported in patients carrying other truncating TULP1 variants. CONCLUSIONS This study describes the progression of TULP1 IRD suggesting a potential time window for therapeutic interventions. The width of the foveal EZ and the thickness of the foveal OPL-ONL layers could serve as biomarkers of the disease stage.
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Affiliation(s)
- Anna Majander
- Department of Ophthalmology, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
| | - Eeva-Marja Sankila
- Department of Ophthalmology, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
| | - Aura Falck
- Department of Ophthalmology, PEDEGO Research Unit and Medical Research Center, University of Oulu and Oulu University Hospital, Oulu, Finland
| | - Laura Kristiina Vasara
- Department of Ophthalmology, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
| | - Sanna Seitsonen
- Department of Ophthalmology, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
| | - Maarit Kulmala
- Department of Ophthalmology, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
| | - Anna-Kaisa Haavisto
- Department of Ophthalmology, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
| | - Kristiina Avela
- Department of Clinical Genetics, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
| | - Joni A Turunen
- Department of Ophthalmology, University of Helsinki and Helsinki University Hospital, Helsinki, Finland.,Eye Genetics Group, Folkhälsan Research Center, Helsinki, Finland
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7
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Rajala A, Rajala R, Gopinadhan Nair GK, Rajala RVS. Atlas of phosphoinositide signatures in the retina identifies heterogeneity between cell types. PNAS NEXUS 2023; 2:pgad063. [PMID: 37007713 PMCID: PMC10062291 DOI: 10.1093/pnasnexus/pgad063] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Revised: 02/11/2023] [Accepted: 02/17/2023] [Indexed: 03/06/2023]
Abstract
Phosphoinositides (PIPs) are a family of minor acidic phospholipids in the cell membrane. Phosphoinositide (PI) kinases and phosphatases can rapidly convert one PIP product into another resulting in the generation of seven distinct PIPs. The retina is a heterogeneous tissue composed of several cell types. In the mammalian genome, around 50 genes encode PI kinases and PI phosphatases; however, there are no studies describing the distribution of these enzymes in the various retinal cell types. Using translating ribosome affinity purification, we have identified the in vivo distribution of PI-converting enzymes from the rod, cone, retinal pigment epithelium (RPE), Müller glia, and retinal ganglion cells, generating a physiological atlas for PI-converting enzyme expression in the retina. The retinal neurons, rods, cones, and RGCs, are characterized by the enrichment of PI-converting enzymes, whereas the Müller glia and RPE are characterized by the depletion of these enzymes. We also found distinct differences between the expression of PI kinases and PI phosphatases in each retinal cell type. Since mutations in PI-converting enzymes are linked to human diseases including retinal diseases, the results of this study will provide a guide for what cell types are likely to be affected by retinal degenerative diseases brought on by changes in PI metabolism.
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Affiliation(s)
- Ammaji Rajala
- Department of Ophthalmology, University of Oklahoma Health Sciences Center, 608 Stanton L. Young Blvd, Oklahoma City, OK 73104, USA
- Dean McGee Eye Institute, 608 Stanton L. Young Blvd, Oklahoma City, OK 73104, USA
| | - Rahul Rajala
- Department of Cell Biology, University of Oklahoma Health Sciences Center, 608 Stanton L. Young Blvd, Oklahoma City, OK 73104, USA
- Cardiovascular Biology Program, Oklahoma Medical Research Foundation, 825 NE 13th St, Oklahoma City, OK 73104, USA
| | - Gopa Kumar Gopinadhan Nair
- Department of Ophthalmology, University of Oklahoma Health Sciences Center, 608 Stanton L. Young Blvd, Oklahoma City, OK 73104, USA
- Dean McGee Eye Institute, 608 Stanton L. Young Blvd, Oklahoma City, OK 73104, USA
| | - Raju V S Rajala
- Department of Ophthalmology, University of Oklahoma Health Sciences Center, 608 Stanton L. Young Blvd, Oklahoma City, OK 73104, USA
- Dean McGee Eye Institute, 608 Stanton L. Young Blvd, Oklahoma City, OK 73104, USA
- Department of Cell Biology, University of Oklahoma Health Sciences Center, 608 Stanton L. Young Blvd, Oklahoma City, OK 73104, USA
- Department of Physiology, University of Oklahoma Health Sciences Center, 608 Stanton L. Young Blvd, Oklahoma City, OK 73104, USA
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8
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Wu KY, Kulbay M, Toameh D, Xu AQ, Kalevar A, Tran SD. Retinitis Pigmentosa: Novel Therapeutic Targets and Drug Development. Pharmaceutics 2023; 15:685. [PMID: 36840007 PMCID: PMC9963330 DOI: 10.3390/pharmaceutics15020685] [Citation(s) in RCA: 18] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Revised: 02/12/2023] [Accepted: 02/16/2023] [Indexed: 02/19/2023] Open
Abstract
Retinitis pigmentosa (RP) is a heterogeneous group of hereditary diseases characterized by progressive degeneration of retinal photoreceptors leading to progressive visual decline. It is the most common type of inherited retinal dystrophy and has a high burden on both patients and society. This condition causes gradual loss of vision, with its typical manifestations including nyctalopia, concentric visual field loss, and ultimately bilateral central vision loss. It is one of the leading causes of visual disability and blindness in people under 60 years old and affects over 1.5 million people worldwide. There is currently no curative treatment for people with RP, and only a small group of patients with confirmed RPE65 mutations are eligible to receive the only gene therapy on the market: voretigene neparvovec. The current therapeutic armamentarium is limited to retinoids, vitamin A supplements, protection from sunlight, visual aids, and medical and surgical interventions to treat ophthalmic comorbidities, which only aim to slow down the progression of the disease. Considering such a limited therapeutic landscape, there is an urgent need for developing new and individualized therapeutic modalities targeting retinal degeneration. Although the heterogeneity of gene mutations involved in RP makes its target treatment development difficult, recent fundamental studies showed promising progress in elucidation of the photoreceptor degeneration mechanism. The discovery of novel molecule therapeutics that can selectively target specific receptors or specific pathways will serve as a solid foundation for advanced drug development. This article is a review of recent progress in novel treatment of RP focusing on preclinical stage fundamental research on molecular targets, which will serve as a starting point for advanced drug development. We will review the alterations in the molecular pathways involved in the development of RP, mainly those regarding endoplasmic reticulum (ER) stress and apoptotic pathways, maintenance of the redox balance, and genomic stability. We will then discuss the therapeutic approaches under development, such as gene and cell therapy, as well as the recent literature identifying novel potential drug targets for RP.
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Affiliation(s)
- Kevin Y. Wu
- Division of Ophthalmology, Department of Surgery, University of Sherbrooke, Sherbrooke, QC J1G 2E8, Canada
| | - Merve Kulbay
- Faculty of Medicine, University of Montreal, Montreal, QC H3T 1J4, Canada
| | - Dana Toameh
- Faculty of Medicine, McGill University, Montreal, QC H3G 2M1, Canada
| | - An Qi Xu
- Faculty of Medicine, University of Montreal, Montreal, QC H3T 1J4, Canada
| | - Ananda Kalevar
- Division of Ophthalmology, Department of Surgery, University of Sherbrooke, Sherbrooke, QC J1G 2E8, Canada
| | - Simon D. Tran
- Faculty of Dental Medicine and Oral Health Sciences, McGill University, Montreal, QC H3A 1G1, Canada
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9
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Bodenbender JP, Marino V, Bethge L, Stingl K, Haack TB, Biskup S, Kohl S, Kühlewein L, Dell’Orco D, Weisschuh N. Biallelic Variants in TULP1 Are Associated with Heterogeneous Phenotypes of Retinal Dystrophy. Int J Mol Sci 2023; 24:ijms24032709. [PMID: 36769033 PMCID: PMC9916573 DOI: 10.3390/ijms24032709] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Revised: 01/24/2023] [Accepted: 01/27/2023] [Indexed: 02/04/2023] Open
Abstract
Biallelic pathogenic variants in TULP1 are mostly associated with severe rod-driven inherited retinal degeneration. In this study, we analyzed clinical heterogeneity in 17 patients and characterized the underlying biallelic variants in TULP1. All patients underwent thorough ophthalmological examinations. Minigene assays and structural analyses were performed to assess the consequences of splice variants and missense variants. Three patients were diagnosed with Leber congenital amaurosis, nine with early onset retinitis pigmentosa, two with retinitis pigmentosa with an onset in adulthood, one with cone dystrophy, and two with cone-rod dystrophy. Seventeen different alleles were identified, namely eight missense variants, six nonsense variants, one in-frame deletion variant, and two splice site variants. For the latter two, minigene assays revealed aberrant transcripts containing frameshifts and premature termination codons. Structural analysis and molecular modeling suggested different degrees of structural destabilization for the missense variants. In conclusion, we report the largest cohort of patients with TULP1-associated IRD published to date. Most of the patients exhibited rod-driven disease, yet a fraction of the patients exhibited cone-driven disease. Our data support the hypothesis that TULP1 variants do not fold properly and thus trigger unfolded protein response, resulting in photoreceptor death.
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Affiliation(s)
- Jan-Philipp Bodenbender
- Department for Ophthalmology, University Eye Hospital, University of Tübingen, 72076 Tübingen, Germany
- Correspondence: (J.-P.B.); (N.W.)
| | - Valerio Marino
- Section of Biological Chemistry, Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, 37124 Verona, Italy
| | - Leon Bethge
- Department for Ophthalmology, University Eye Hospital, University of Tübingen, 72076 Tübingen, Germany
| | - Katarina Stingl
- Department for Ophthalmology, University Eye Hospital, University of Tübingen, 72076 Tübingen, Germany
| | - Tobias B. Haack
- Institute of Medical Genetics and Applied Genomics, University of Tübingen, 72076 Tübingen, Germany
- Centre for Rare Diseases, University of Tübingen, 72076 Tübingen, Germany
| | - Saskia Biskup
- Praxis für Humangenetik, 72076 Tübingen, Germany
- CeGaT GmbH, 72076 Tübingen, Germany
| | - Susanne Kohl
- Department for Ophthalmology, Institute for Ophthalmic Research, University of Tübingen, 72076 Tübingen, Germany
| | - Laura Kühlewein
- Department for Ophthalmology, University Eye Hospital, University of Tübingen, 72076 Tübingen, Germany
| | - Daniele Dell’Orco
- Section of Biological Chemistry, Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, 37124 Verona, Italy
| | - Nicole Weisschuh
- Department for Ophthalmology, Institute for Ophthalmic Research, University of Tübingen, 72076 Tübingen, Germany
- Correspondence: (J.-P.B.); (N.W.)
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10
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Tulp1 deficiency causes early-onset retinal degeneration through affecting ciliogenesis and activating ferroptosis in zebrafish. Cell Death Dis 2022; 13:962. [PMID: 36396940 PMCID: PMC9672332 DOI: 10.1038/s41419-022-05372-w] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Revised: 10/22/2022] [Accepted: 10/24/2022] [Indexed: 11/19/2022]
Abstract
Mutations in TUB-like protein 1 (TULP1) are associated with severe early-onset retinal degeneration in humans. However, the pathogenesis remains largely unknown. There are two homologous genes of TULP1 in zebrafish, namely tulp1a and tulp1b. Here, we generated the single knockout (tulp1a-/- and tulp1b-/-) and double knockout (tulp1-dKO) models in zebrafish. Knockout of tulp1a resulted in the mislocalization of UV cone opsins and the degeneration of UV cones specifically, while knockout of tulp1b resulted in mislocalization of rod opsins and rod-cone degeneration. In the tulp1-dKO zebrafish, mislocalization of opsins was present in all types of photoreceptors, and severe degeneration was observed at a very early age, mimicking the clinical manifestations of TULP1 patients. Photoreceptor cilium length was significantly reduced in the tulp1-dKO retinas. RNA-seq analysis showed that the expression of tektin2 (tekt2), a ciliary and flagellar microtubule structural component, was downregulated in the tulp1-dKO zebrafish. Dual-luciferase reporter assay suggested that Tulp1a and Tulp1b transcriptionally activate the promoter of tekt2. In addition, ferroptosis might be activated in the tulp1-dKO zebrafish, as suggested by the up-regulation of genes related to the ferroptosis pathway, the shrinkage of mitochondria, reduction or disappearance of mitochondria cristae, and the iron and lipid droplet deposition in the retina of tulp1-dKO zebrafish. In conclusion, our study establishes an appropriate zebrafish model for TULP1-associated retinal degeneration and proposes that loss of TULP1 causes defects in cilia structure and opsin trafficking through the downregulation of tekt2, which further increases the death of photoreceptors via ferroptosis. These findings offer insight into the pathogenesis and clinical treatment of early-onset retinal degeneration.
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TULP1 related retinal dystrophy: report of rare and novel variants with a previously undescribed phenotype in two cases. Ophthalmic Genet 2021; 43:277-281. [PMID: 34865612 DOI: 10.1080/13816810.2021.2010769] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
PURPOSE To report on two rare and one novel TULP1 pathogenic variants in two patients associated with a previously uncharacterized phenotype of retinal degeneration. METHODS Case report. RESULTS A 4 year-old and a 19 year-old female presented with reduced vision and bilateral bull's eye maculopathy. In both patients, a unique pattern of perivascular retinal degeneration was noted. Electroretinography was consistent with a cone-rod dystrophy. Sequence analysis identified pathogenic variants in the TULP1 gene c.1087 G > A, p.(Gly363Arg); c.1568 G > A, p.(Cys523Tyr); and c.821delA, p.(Lys274ArgfsTer36). CONCLUSION Patients with TULP1-related retinal dystrophy can have a distinctive retinopathy with a unique pattern of macular degeneration and periarteriolar vascular pigmentation.
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12
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Roman AJ, Cideciyan AV, Wu V, Garafalo AV, Jacobson SG. Full-field stimulus testing: Role in the clinic and as an outcome measure in clinical trials of severe childhood retinal disease. Prog Retin Eye Res 2021; 87:101000. [PMID: 34464742 DOI: 10.1016/j.preteyeres.2021.101000] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Revised: 08/24/2021] [Accepted: 08/27/2021] [Indexed: 12/27/2022]
Abstract
Disease mechanisms have become better understood in previously incurable forms of early-onset severe retinal dystrophy, such as Leber congenital amaurosis (LCA). This has led to novel treatments and clinical trials that have shown some success. Standard methods to measure vision were difficult if not impossible to perform in severely affected patients with low vision and nystagmus. To meet the need for visual assays, we devised a psychophysical method, which we named full-field stimulus testing (FST). From early versions based on an automated perimeter, we advanced FST to a more available light-emitting diode platform. The journey from invention to use of such a technique in our inherited retinal degeneration clinic is reviewed and many of the lessons learned over the 15 years of application of FST are explained. Although the original purpose and application of FST was to quantify visual thresholds in LCA, there are rare opportunities for FST also to be used beyond LCA to measure aspects of vision in other inherited retinal degenerations; examples are given. The main goal of the current review, however, remains to enable investigators studying and treating LCA to understand how to best use FST and how to reduce artefact and confounding complexities so the test results become more valuable to the understanding of LCA diseases and results of novel interventions.
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Affiliation(s)
- Alejandro J Roman
- Scheie Eye Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Artur V Cideciyan
- Scheie Eye Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Vivian Wu
- Scheie Eye Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Alexandra V Garafalo
- Scheie Eye Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Samuel G Jacobson
- Scheie Eye Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA.
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13
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Huang CH, Yang CM, Yang CH, Hou YC, Chen TC. Leber's Congenital Amaurosis: Current Concepts of Genotype-Phenotype Correlations. Genes (Basel) 2021; 12:genes12081261. [PMID: 34440435 PMCID: PMC8392113 DOI: 10.3390/genes12081261] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Revised: 08/15/2021] [Accepted: 08/18/2021] [Indexed: 12/26/2022] Open
Abstract
Leber’s congenital amaurosis (LCA), one of the most severe inherited retinal dystrophies, is typically associated with extremely early onset of visual loss, nystagmus, and amaurotic pupils, and is responsible for 20% of childhood blindness. With advances in molecular diagnostic technology, the knowledge about the genetic background of LCA has expanded widely, while disease-causing variants have been identified in 38 genes. Different pathogenetic mechanisms have been found among these varieties of genetic mutations, all of which result in the dysfunction or absence of their encoded proteins participating in the visual cycle. Hence, the clinical phenotypes also exhibit extensive heterogenicity, including the course of visual impairment, involvement of the macular area, alteration in retinal structure, and residual function of the diseased photoreceptor. By reviewing the clinical course, fundoscopic images, optical coherent tomography examination, and electroretinogram, genotype-phenotype correlations could be established for common genetic mutations in LCA, which would benefit the timing of the diagnosis and thus promote early intervention. Gene therapy is promising in the management of LCA, while several clinical trials are ongoing and preliminary success has been announced, focusing on RPE65 and other common disease-causing genes. This review provides an update on the genetics, clinical examination findings, and genotype-phenotype correlations in the most well-established causative genetic mutations of LCA.
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Affiliation(s)
- Chu-Hsuan Huang
- Department of Ophthalmology, Cathay General Hospital, Taipei 106, Taiwan; (C.-H.H.); (Y.-C.H.)
| | - Chung-May Yang
- Department of Ophthalmology, National Taiwan University Hospital, Taipei 100, Taiwan; (C.-M.Y.); (C.-H.Y.)
- Department of Ophthalmology, College of Medicine, National Taiwan University, Taipei 100, Taiwan
| | - Chang-Hao Yang
- Department of Ophthalmology, National Taiwan University Hospital, Taipei 100, Taiwan; (C.-M.Y.); (C.-H.Y.)
- Department of Ophthalmology, College of Medicine, National Taiwan University, Taipei 100, Taiwan
| | - Yu-Chih Hou
- Department of Ophthalmology, Cathay General Hospital, Taipei 106, Taiwan; (C.-H.H.); (Y.-C.H.)
| | - Ta-Ching Chen
- Department of Ophthalmology, National Taiwan University Hospital, Taipei 100, Taiwan; (C.-M.Y.); (C.-H.Y.)
- Correspondence: ; Tel.: +886-2-23123456
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14
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Shang P, Stepicheva N, Teel K, McCauley A, Fitting CS, Hose S, Grebe R, Yazdankhah M, Ghosh S, Liu H, Strizhakova A, Weiss J, Bhutto IA, Lutty GA, Jayagopal A, Qian J, Sahel JA, Samuel Zigler J, Handa JT, Sergeev Y, Rajala RVS, Watkins S, Sinha D. βA3/A1-crystallin regulates apical polarity and EGFR endocytosis in retinal pigmented epithelial cells. Commun Biol 2021; 4:850. [PMID: 34239035 PMCID: PMC8266859 DOI: 10.1038/s42003-021-02386-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Accepted: 06/24/2021] [Indexed: 12/20/2022] Open
Abstract
The retinal pigmented epithelium (RPE) is a monolayer of multifunctional cells located at the back of the eye. High membrane turnover and polarization, including formation of actin-based apical microvilli, are essential for RPE function and retinal health. Herein, we demonstrate an important role for βA3/A1-crystallin in RPE. βA3/A1-crystallin deficiency leads to clathrin-mediated epidermal growth factor receptor (EGFR) endocytosis abnormalities and actin network disruption at the apical side that result in RPE polarity disruption and degeneration. We found that βA3/A1-crystallin binds to phosphatidylinositol transfer protein (PITPβ) and that βA3/A1-crystallin deficiency diminishes phosphatidylinositol 4,5-biphosphate (PI(4,5)P2), thus probably decreasing ezrin phosphorylation, EGFR activation, internalization, and degradation. We propose that βA3/A1-crystallin acquired its RPE function before evolving as a structural element in the lens, and that in the RPE, it modulates the PI(4,5)P2 pool through PITPβ/PLC signaling axis, coordinates EGFR activation, regulates ezrin phosphorylation and ultimately the cell polarity.
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Affiliation(s)
- Peng Shang
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Nadezda Stepicheva
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Kenneth Teel
- Dean McGee Eye Institute, University of Oklahoma Health Science Center, Oklahoma City, OK, USA
| | - Austin McCauley
- Dean McGee Eye Institute, University of Oklahoma Health Science Center, Oklahoma City, OK, USA
| | | | - Stacey Hose
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Rhonda Grebe
- Wilmer Eye Institute, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Meysam Yazdankhah
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Sayan Ghosh
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Haitao Liu
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Anastasia Strizhakova
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Joseph Weiss
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Imran A Bhutto
- Wilmer Eye Institute, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Gerard A Lutty
- Wilmer Eye Institute, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | | | - Jiang Qian
- Wilmer Eye Institute, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - José-Alain Sahel
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
- Institut de la Vision, INSERM, CNRS, Sorbonne Université, Paris, France
| | - J Samuel Zigler
- Wilmer Eye Institute, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - James T Handa
- Wilmer Eye Institute, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Yuri Sergeev
- National Eye Institute, National Institutes of Health, Bethesda, MD, USA
| | - Raju V S Rajala
- Dean McGee Eye Institute, University of Oklahoma Health Science Center, Oklahoma City, OK, USA
| | - Simon Watkins
- Department of Cell Biology and Center for Biologic Imaging, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Debasish Sinha
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.
- Wilmer Eye Institute, The Johns Hopkins University School of Medicine, Baltimore, MD, USA.
- Department of Cell Biology and Center for Biologic Imaging, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.
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15
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Zhou L, Matsushima GK. Tyro3, Axl, Mertk receptor-mediated efferocytosis and immune regulation in the tumor environment. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2021; 361:165-210. [PMID: 34074493 DOI: 10.1016/bs.ircmb.2021.02.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Three structurally related tyrosine receptor cell surface kinases, Tyro3, Axl, and Mertk (TAM) have been recognized to modulate immune function, tissue homeostasis, cardiovasculature, and cancer. The TAM receptor family appears to operate in adult mammals across multiple cell types, suggesting both widespread and specific regulation of cell functions and immune niches. TAM family members regulate tissue homeostasis by monitoring the presence of phosphatidylserine expressed on stressed or apoptotic cells. The detection of phosphatidylserine on apoptotic cells requires intermediary molecules that opsonize the dying cells and tether them to TAM receptors on phagocytes. This complex promotes the engulfment of apoptotic cells, also known as efferocytosis, that leads to the resolution of inflammation and tissue healing. The immune mechanisms dictating these processes appear to fall upon specific family members or may involve a complex of different receptors acting cooperatively to resolve and repair damaged tissues. Here, we focus on the role of TAM receptors in triggering efferocytosis and its consequences in the regulation of immune responses in the context of inflammation and cancer.
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Affiliation(s)
- Liwen Zhou
- UNC Neuroscience Center, University of North Carolina-CH, Chapel Hill, NC, United States
| | - Glenn K Matsushima
- UNC Neuroscience Center, University of North Carolina-CH, Chapel Hill, NC, United States; UNC Department of Microbiology & Immunology, University of North Carolina-CH, Chapel Hill, NC, United States; UNC Integrative Program for Biological & Genome Sciences, University of North Carolina-CH, Chapel Hill, NC, United States.
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16
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Gene therapy reforms photoreceptor structure and restores vision in NPHP5-associated Leber congenital amaurosis. Mol Ther 2021; 29:2456-2468. [PMID: 33781914 DOI: 10.1016/j.ymthe.2021.03.021] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Revised: 12/21/2020] [Accepted: 03/23/2021] [Indexed: 02/03/2023] Open
Abstract
The inherited childhood blindness caused by mutations in NPHP5, a form of Leber congenital amaurosis, results in abnormal development, dysfunction, and degeneration of photoreceptors. A naturally occurring NPHP5 mutation in dogs leads to a phenotype that very nearly duplicates the human retinopathy in terms of the photoreceptors involved, spatial distribution of degeneration, and the natural history of vision loss. We show that adeno-associated virus (AAV)-mediated NPHP5 gene augmentation of mutant canine retinas at the time of active degeneration and peak cell death stably restores photoreceptor structure, function, and vision with either the canine or human NPHP5 transgenes. Mutant cone photoreceptors, which failed to form outer segments during development, reform this structure after treatment. Degenerating rod photoreceptor outer segments are stabilized and develop normal structure. This process begins within 8 weeks after treatment and remains stable throughout the 6-month posttreatment period. In both photoreceptor cell classes mislocalization of rod and cone opsins is minimized or reversed. Retinal function and functional vision are restored. Efficacy of gene therapy in this large animal ciliopathy model of Leber congenital amaurosis provides a path for translation to human treatment.
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17
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Sánchez-Bellver L, Toulis V, Marfany G. On the Wrong Track: Alterations of Ciliary Transport in Inherited Retinal Dystrophies. Front Cell Dev Biol 2021; 9:623734. [PMID: 33748110 PMCID: PMC7973215 DOI: 10.3389/fcell.2021.623734] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Accepted: 02/09/2021] [Indexed: 01/14/2023] Open
Abstract
Ciliopathies are a group of heterogeneous inherited disorders associated with dysfunction of the cilium, a ubiquitous microtubule-based organelle involved in a broad range of cellular functions. Most ciliopathies are syndromic, since several organs whose cells produce a cilium, such as the retina, cochlea or kidney, are affected by mutations in ciliary-related genes. In the retina, photoreceptor cells present a highly specialized neurosensory cilium, the outer segment, stacked with membranous disks where photoreception and phototransduction occurs. The daily renewal of the more distal disks is a unique characteristic of photoreceptor outer segments, resulting in an elevated protein demand. All components necessary for outer segment formation, maintenance and function have to be transported from the photoreceptor inner segment, where synthesis occurs, to the cilium. Therefore, efficient transport of selected proteins is critical for photoreceptor ciliogenesis and function, and any alteration in either cargo delivery to the cilium or intraciliary trafficking compromises photoreceptor survival and leads to retinal degeneration. To date, mutations in more than 100 ciliary genes have been associated with retinal dystrophies, accounting for almost 25% of these inherited rare diseases. Interestingly, not all mutations in ciliary genes that cause retinal degeneration are also involved in pleiotropic pathologies in other ciliated organs. Depending on the mutation, the same gene can cause syndromic or non-syndromic retinopathies, thus emphasizing the highly refined specialization of the photoreceptor neurosensory cilia, and raising the possibility of photoreceptor-specific molecular mechanisms underlying common ciliary functions such as ciliary transport. In this review, we will focus on ciliary transport in photoreceptor cells and discuss the molecular complexity underpinning retinal ciliopathies, with a special emphasis on ciliary genes that, when mutated, cause either syndromic or non-syndromic retinal ciliopathies.
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Affiliation(s)
- Laura Sánchez-Bellver
- Departament de Genètica, Microbiologia i Estadística, Universitat de Barcelona, Barcelona, Spain
- Institute of Biomedicine (IBUB-IRSJD), Universitat de Barcelona, Barcelona, Spain
| | - Vasileios Toulis
- Departament de Genètica, Microbiologia i Estadística, Universitat de Barcelona, Barcelona, Spain
- CIBERER, ISCIII, Universitat de Barcelona, Barcelona, Spain
| | - Gemma Marfany
- Departament de Genètica, Microbiologia i Estadística, Universitat de Barcelona, Barcelona, Spain
- Institute of Biomedicine (IBUB-IRSJD), Universitat de Barcelona, Barcelona, Spain
- CIBERER, ISCIII, Universitat de Barcelona, Barcelona, Spain
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18
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Palfi A, Yesmambetov A, Millington-Ward S, Shortall C, Humphries P, Kenna PF, Chadderton N, Farrar GJ. AAV-Delivered Tulp1 Supplementation Therapy Targeting Photoreceptors Provides Minimal Benefit in Tulp1-/- Retinas. Front Neurosci 2020; 14:891. [PMID: 32973439 PMCID: PMC7482550 DOI: 10.3389/fnins.2020.00891] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Accepted: 07/30/2020] [Indexed: 12/23/2022] Open
Abstract
With marketing approval of the first ocular gene therapy, and other gene therapies in clinical trial, treatments for inherited retinal degenerations (IRDs) have become a reality. Biallelic mutations in the tubby like protein 1 gene (TULP1) are causative of IRDs in humans; a mouse knock-out model (Tulp1−/−) is characterized by a similar disease phenotype. We developed a Tulp1 supplementation therapy for Tulp1−/− mice. Utilizing subretinal AAV2/5 delivery at postnatal day (p)2–3 and rhodopsin-kinase promoter (GRK1P) we targeted Tulp1 to photoreceptor cells exploring three doses, 2.2E9, 3.7E8, and 1.2E8 vgs. Tulp1 mRNA and TULP1 protein were assessed by RT-qPCR, western blot and immunocytochemistry, and visual function by electroretinography. Our results indicate that TULP1 was expressed in photoreceptors; achieved levels of Tulp1 mRNA and protein were similar to wild type levels at p20. However, the thickness of the outer nuclear layer (ONL) did not improve in treated Tulp1−/− mice. There was a small and transient electroretinography benefit in the treated retinas at 4 weeks of age (not observed by 6 weeks) when using 3.7E8 vg dose. Dark-adapted mixed rod and cone a- and b-wave amplitudes were 24.3 ± 13.5 μV and 52.2 ± 31.7 μV in treated Tulp1−/− mice, which were significantly different (p < 0.001, t-test), from those detected in untreated eyes (7.1 ± 7.0 μV and 9.4 ± 15.1 μV, respectively). Our results indicate that Tulp1 supplementation in photoreceptors may not be sufficient to provide robust benefit in Tulp1−/− mice. As such, further studies are required to fine tune the Tulp1 supplementation therapy, which, in principle, should rescue the Tulp1−/− phenotype.
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Affiliation(s)
- Arpad Palfi
- Department of Genetics, School of Genetics and Microbiology, Trinity College Dublin, Dublin, Ireland
| | - Adlet Yesmambetov
- Department of Genetics, School of Genetics and Microbiology, Trinity College Dublin, Dublin, Ireland
| | - Sophia Millington-Ward
- Department of Genetics, School of Genetics and Microbiology, Trinity College Dublin, Dublin, Ireland
| | - Ciara Shortall
- Department of Genetics, School of Genetics and Microbiology, Trinity College Dublin, Dublin, Ireland
| | - Pete Humphries
- Department of Genetics, School of Genetics and Microbiology, Trinity College Dublin, Dublin, Ireland
| | - Paul F Kenna
- Department of Genetics, School of Genetics and Microbiology, Trinity College Dublin, Dublin, Ireland
| | - Naomi Chadderton
- Department of Genetics, School of Genetics and Microbiology, Trinity College Dublin, Dublin, Ireland
| | - G Jane Farrar
- Department of Genetics, School of Genetics and Microbiology, Trinity College Dublin, Dublin, Ireland
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Sumaroka A, Cideciyan AV, Sheplock R, Wu V, Kohl S, Wissinger B, Jacobson SG. Foveal Therapy in Blue Cone Monochromacy: Predictions of Visual Potential From Artificial Intelligence. Front Neurosci 2020; 14:800. [PMID: 32848570 PMCID: PMC7416698 DOI: 10.3389/fnins.2020.00800] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Accepted: 07/07/2020] [Indexed: 11/13/2022] Open
Abstract
Novel therapeutic approaches for treating inherited retinal degenerations (IRDs) prompt a need to understand which patients with impaired vision have the anatomical potential to gain from participation in a clinical trial. We used supervised machine learning to predict foveal function from foveal structure in blue cone monochromacy (BCM), an X-linked congenital cone photoreceptor dysfunction secondary to mutations in the OPN1LW/OPN1MW gene cluster. BCM patients with either disease-associated large deletion or missense mutations were studied and results compared with those from subjects with other forms of IRD and various degrees of preserved central structure and function. A machine learning technique was used to associate foveal sensitivities and best-corrected visual acuities to foveal structure in IRD patients. Two random forest (RF) models trained on IRD data were applied to predict foveal function in BCM. A curve fitting method was also used and results compared with those of the RF models. The BCM and IRD patients had a comparable range of foveal structure. IRD patients had peak sensitivity at the fovea. Machine learning could successfully predict foveal sensitivity (FS) results from segmented or un-segmented optical coherence tomography (OCT) input. Application of machine learning predictions to BCM at the fovea showed differences between predicted and measured sensitivities, thereby defining treatment potential. The curve fitting method provided similar results. Given a measure of visual acuity (VA) and foveal outer nuclear layer thickness, the question of how many lines of acuity would represent the best efficacious result for each BCM patient could be answered. We propose that foveal vision improvement potential in BCM is predictable from retinal structure using machine learning and curve fitting approaches. This should allow estimates of maximal efficacy in patients being considered for clinical trials and also guide decisions about dosing.
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Affiliation(s)
- Alexander Sumaroka
- Scheie Eye Institute, Department of Ophthalmology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Artur V. Cideciyan
- Scheie Eye Institute, Department of Ophthalmology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Rebecca Sheplock
- Scheie Eye Institute, Department of Ophthalmology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Vivian Wu
- Scheie Eye Institute, Department of Ophthalmology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Susanne Kohl
- Molecular Genetics Laboratory, Institute for Ophthalmic Research, Centre for Ophthalmology, University of Tüebingen, Tüebingen, Germany
| | - Bernd Wissinger
- Molecular Genetics Laboratory, Institute for Ophthalmic Research, Centre for Ophthalmology, University of Tüebingen, Tüebingen, Germany
| | - Samuel G. Jacobson
- Scheie Eye Institute, Department of Ophthalmology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
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20
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Garafalo AV, Cideciyan AV, Héon E, Sheplock R, Pearson A, WeiYang Yu C, Sumaroka A, Aguirre GD, Jacobson SG. Progress in treating inherited retinal diseases: Early subretinal gene therapy clinical trials and candidates for future initiatives. Prog Retin Eye Res 2020; 77:100827. [PMID: 31899291 PMCID: PMC8714059 DOI: 10.1016/j.preteyeres.2019.100827] [Citation(s) in RCA: 109] [Impact Index Per Article: 27.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2019] [Revised: 12/21/2019] [Accepted: 12/26/2019] [Indexed: 12/15/2022]
Abstract
Due to improved phenotyping and genetic characterization, the field of 'incurable' and 'blinding' inherited retinal diseases (IRDs) has moved substantially forward. Decades of ascertainment of IRD patient data from Philadelphia and Toronto centers illustrate the progress from Mendelian genetic types to molecular diagnoses. Molecular genetics have been used not only to clarify diagnoses and to direct counseling but also to enable the first clinical trials of gene-based treatment in these diseases. An overview of the recent reports of gene augmentation clinical trials by subretinal injections is used to reflect on the reasons why there has been limited success in this early venture into therapy. These first-in human experiences have taught that there is a need for advancing the techniques of delivery of the gene products - not only for refining further subretinal trials, but also for evaluating intravitreal delivery. Candidate IRDs for intravitreal gene delivery are then suggested to illustrate some of the disorders that may be amenable to improvement of remaining central vision with the least photoreceptor trauma. A more detailed understanding of the human IRDs to be considered for therapy and the calculated potential for efficacy should be among the routine prerequisites for initiating a clinical trial.
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Affiliation(s)
- Alexandra V Garafalo
- Scheie Eye Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Artur V Cideciyan
- Scheie Eye Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Elise Héon
- Department of Ophthalmology and Vision Sciences, The Hospital for Sick Children, University of Toronto, Toronto, ON, Canada
| | - Rebecca Sheplock
- Scheie Eye Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Alexander Pearson
- Department of Ophthalmology and Vision Sciences, The Hospital for Sick Children, University of Toronto, Toronto, ON, Canada
| | - Caberry WeiYang Yu
- Department of Ophthalmology and Vision Sciences, The Hospital for Sick Children, University of Toronto, Toronto, ON, Canada
| | - Alexander Sumaroka
- Scheie Eye Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Gustavo D Aguirre
- Division of Experimental Retinal Therapies, Department of Clinical Sciences & Advanced Medicine, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Samuel G Jacobson
- Scheie Eye Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA.
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Palfi A, Yesmambetov A, Humphries P, Hokamp K, Farrar GJ. Non-photoreceptor Expression of Tulp1 May Contribute to Extensive Retinal Degeneration in Tulp1-/- Mice. Front Neurosci 2020; 14:656. [PMID: 32655363 PMCID: PMC7325604 DOI: 10.3389/fnins.2020.00656] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Accepted: 05/27/2020] [Indexed: 12/24/2022] Open
Abstract
Mutations in tubby like protein 1 gene (TULP1) are causative of early-onset recessive inherited retinal degenerations (IRDs); similarly, the Tulp1-/- mouse is also characterized by a rapid IRD. Tulp1 mRNA and protein expression was analyzed in wild type mouse retinas and expression data sets (NCBI) during early postnatal development. Comparative histology was undertaken in Tulp1-/-, rhodopsin-/- (Rho-/-) and retinal degeneration slow-/- (Rds-/-) mouse retinas. Bioinformatic analysis of predicted TULP1 interactors and IRD genes was performed. Peak expression of Tulp1 in healthy mouse retinas was detected at p8; of note, TULP1 was detected in both the outer and inner retina. Bioinformatic analysis indicated Tulp1 expression in retinal progenitor, photoreceptor and non-photoreceptor cells. While common features of photoreceptor degeneration were detected in Tulp1-/-, Rho-/-, and Rds-/- retinas, other alterations in bipolar, amacrine and ganglion cells were specific to Tulp1-/- mice. Additionally, predicted TULP1 interactors differed in various retinal cell types and new functions for TULP1 were suggested. A pilot bioinformatic analysis indicated that in a similar fashion to Tulp1, many other IRD genes were expressed in both inner and outer retinal cells at p4-p7. Our data indicate that expression of Tulp1 extends to multiple retinal cell types; lack of TULP1 may lead to primary degeneration not only of photoreceptor but also non-photoreceptor cells. Predicted interactors suggest widespread retinal functions for TULP1. Early and widespread expression of TULP1 and some other IRD genes in both the inner and outer retina highlights potential hurdles in the development of treatments for these IRDs.
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Affiliation(s)
- Arpad Palfi
- Department of Genetics, Trinity College Dublin, Dublin, Ireland
| | | | - Pete Humphries
- Department of Genetics, Trinity College Dublin, Dublin, Ireland
| | - Karsten Hokamp
- Department of Genetics, Trinity College Dublin, Dublin, Ireland
| | - G Jane Farrar
- Department of Genetics, Trinity College Dublin, Dublin, Ireland
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22
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Phosphoinositides in Retinal Function and Disease. Cells 2020; 9:cells9040866. [PMID: 32252387 PMCID: PMC7226789 DOI: 10.3390/cells9040866] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2020] [Revised: 03/26/2020] [Accepted: 03/30/2020] [Indexed: 02/06/2023] Open
Abstract
Phosphatidylinositol and its phosphorylated derivatives, the phosphoinositides, play many important roles in all eukaryotic cells. These include modulation of physical properties of membranes, activation or inhibition of membrane-associated proteins, recruitment of peripheral membrane proteins that act as effectors, and control of membrane trafficking. They also serve as precursors for important second messengers, inositol (1,4,5) trisphosphate and diacylglycerol. Animal models and human diseases involving defects in phosphoinositide regulatory pathways have revealed their importance for function in the mammalian retina and retinal pigmented epithelium. New technologies for localizing, measuring and genetically manipulating them are revealing new information about their importance for the function and health of the vertebrate retina.
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Sumaroka A, Garafalo AV, Semenov EP, Sheplock R, Krishnan AK, Roman AJ, Jacobson SG, Cideciyan AV. Treatment Potential for Macular Cone Vision in Leber Congenital Amaurosis Due to CEP290 or NPHP5 Mutations: Predictions From Artificial Intelligence. Invest Ophthalmol Vis Sci 2019; 60:2551-2562. [PMID: 31212307 PMCID: PMC6586080 DOI: 10.1167/iovs.19-27156] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Purpose To use supervised machine learning to predict visual function from retinal structure in retinitis pigmentosa (RP) and apply these estimates to CEP290- and NPHP5-associated Leber congenital amaurosis (LCA) to determine the potential for functional improvement. Methods Patients with RP (n = 20) and LCA due to CEP290 (n = 12) or NPHP5 (n = 6) mutations were studied. A patient with CEP290 mutations but mild retinal degeneration was included. RP patients had cone-mediated macular function. A machine learning technique was used to associate perimetric sensitivities to local structure in RP patients. Models trained on RP data were applied to predict visual function in LCA. Results The RP and LCA patients had comparable retinal structure. RP patients had peak sensitivity at the fovea surrounded by decreasing sensitivity. Machine learning could successfully predict perimetry results from segmented or unsegmented optical coherence tomography (OCT) input. Application of machine learning predictions to LCA within the residual macular island of photoreceptor structure showed differences between predicted and measured sensitivities defining treatment potential. In patients with retained vision, the treatment potential was 4.6 ± 2.9 dB at the fovea but 16.4 ± 4.4 dB at the parafovea. In patients with limited or no vision, the treatment potential was 17.6 ± 9.4 dB. Conclusions Cone vision improvement potential in LCA due to CEP290 or NPHP5 mutations is predictable from retinal structure using a machine learning approach. This should allow individual prediction of the maximal efficacy in clinical trials and guide decisions about dosing. Similar strategies can be used in other retinal degenerations to estimate the extent and location of treatment potential.
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Affiliation(s)
- Alexander Sumaroka
- Scheie Eye Institute, Department of Ophthalmology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States
| | - Alexandra V Garafalo
- Scheie Eye Institute, Department of Ophthalmology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States
| | - Evelyn P Semenov
- Scheie Eye Institute, Department of Ophthalmology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States
| | - Rebecca Sheplock
- Scheie Eye Institute, Department of Ophthalmology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States
| | - Arun K Krishnan
- Scheie Eye Institute, Department of Ophthalmology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States
| | - Alejandro J Roman
- Scheie Eye Institute, Department of Ophthalmology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States
| | - Samuel G Jacobson
- Scheie Eye Institute, Department of Ophthalmology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States
| | - Artur V Cideciyan
- Scheie Eye Institute, Department of Ophthalmology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States
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24
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Avela K, Salonen‐Kajander R, Laitinen A, Ramsden S, Barton S, Rudanko S. The genetic aetiology of retinal degeneration in children in Finland - new founder mutations identified. Acta Ophthalmol 2019; 97:805-814. [PMID: 31087526 DOI: 10.1111/aos.14128] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Accepted: 04/10/2019] [Indexed: 01/22/2023]
Abstract
PURPOSE To study the genetic aetiology and phenotypes of retinal degeneration (RD) in Finnish children born during 1993-2009. METHODS Children with retinal degeneration (N = 68) were investigated during 2012-2014 with a targeted gene analysis or a next-generation sequencing (NGS) based gene panel. Also, a full clinical ophthalmological examination was performed. RESULTS The cohort covered 44% (68/153) of the Finnish children with inherited RD born 1993-2009. X-linked retinoschisis, retinitis pigmentosa, Leber congenital amaurosis and cone-rod dystrophy were the most common clinical diagnoses in the study group. Pathogenic mutations were found in 17 retinal genes. The molecular genetic aetiology was identified in 77% of the patients (in 77% of the families) analysed by NGS method. Several founder mutations were detected including three novel founder mutations c.148delG in TULP1, c.2314C>R (p.Gln772Ter) in RPGRIP1 and c.533G>A (Trp178Ter) in TYR. We also confirmed the previous tentative finding of c.2944 + 1delG in GYCU2D being the most frequent cause of Leber congenital amaurosis (LCA) in Finland. CONCLUSIONS Globally, RD is genetically heterogeneous with over 260 disease genes reported so far. This was shown not to be the case in Finland, where the genetic aetiology of RD is caused by a small group of genes, due to several founder mutations that are enriched in the population. We found that X-chromosomal retinoschisis constitutes the major group in Finnish paediatric RD population and is almost exclusively caused by two founder mutations. Several other founder mutations were detected including three novel founder mutations. All in all, the genetic aetiology of 77% of families was identified which is higher than previously reported from other populations, likely due to the specific genomic constitution of the Finns.
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Affiliation(s)
- Kristiina Avela
- The Department of Clinical Genetics Helsinki University Hospital, HUSLAB Helsinki Finland
| | | | - Arja Laitinen
- The Department of Ophthalmology Helsinki University Hospital Helsinki Finland
| | - Simon Ramsden
- St Mary′s Hospital Central Manchester University Hospitals and Manchester Centre for Genomic Medicine Manchester UK
| | - Stephanie Barton
- St Mary′s Hospital Central Manchester University Hospitals and Manchester Centre for Genomic Medicine Manchester UK
| | - Sirkka‐Liisa Rudanko
- Visio Low Vision Research Centre Finnish Federation of the Visually Impaired Helsinki Finland
- Finnish Register of Visual Impairment by National Institute for Health and Welfare Helsinki Finland
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25
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Chen X, Sheng X, Liu Y, Li Z, Sun X, Jiang C, Qi R, Yuan S, Wang X, Zhou G, Zhen Y, Xie P, Liu Q, Yan B, Zhao C. Distinct mutations with different inheritance mode caused similar retinal dystrophies in one family: a demonstration of the importance of genetic annotations in complicated pedigrees. J Transl Med 2018; 16:145. [PMID: 29843741 PMCID: PMC5975579 DOI: 10.1186/s12967-018-1522-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Accepted: 05/17/2018] [Indexed: 12/03/2022] Open
Abstract
Background Retinitis pigmentosa (RP) is the most common form of inherited retinal dystrophy presenting remarkable genetic heterogeneity. Genetic annotations would help with better clinical assessments and benefit gene therapy, and therefore should be recommended for RP patients. This report reveals the disease causing mutations in two RP pedigrees with confusing inheritance patterns using whole exome sequencing (WES). Methods Twenty-five participants including eight patients from two families were recruited and received comprehensive ophthalmic evaluations. WES was applied for mutation identification. Bioinformatics annotations, intrafamilial co-segregation tests, and in silico analyses were subsequently conducted for mutation verification. Results All patients were clinically diagnosed with RP. The first family included two siblings born to parents with consanguineous marriage; however, no potential pathogenic variant was found shared by both patients. Further analysis revealed that the female patient carried a recurrent homozygous C8ORF37 p.W185*, while the male patient had hemizygous OFD1 p.T120A. The second family was found to segregate mutations in two genes, TULP1 and RP1. Two patients born to consanguineous marriage carried homozygous TULP1 p.R419W, while a recurrent heterozygous RP1 p.L762Yfs*17 was found in another four patients presenting an autosomal dominant inheritance pattern. Crystal structural analysis further indicated that the substitution from arginine to tryptophan at the highly conserved residue 419 of TULP1 could lead to the elimination of two hydrogen bonds between residue 419 and residues V488 and S534. All four genes, including C8ORF37, OFD1, TULP1 and RP1, have been previously implicated in RP etiology. Conclusions Our study demonstrates the coexistence of diverse inheritance modes and mutations affecting distinct disease causing genes in two RP families with consanguineous marriage. Our data provide novel insights into assessments of complicated pedigrees, reinforce the genetic complexity of RP, and highlight the need for extensive molecular evaluations in such challenging families with diverse inheritance modes and mutations. Electronic supplementary material The online version of this article (10.1186/s12967-018-1522-7) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Xue Chen
- Department of Ophthalmology, State Key Laboratory of Reproductive Medicine, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China.,Department of Ophthalmology and Vision Science, Eye & ENT Hospital, Shanghai Medical College, Fudan University, Shanghai, China.,Key Laboratory of Myopia of State Health Ministry (Fudan University) and Shanghai Key Laboratory of Visual Impairment and Restoration, Shanghai, China
| | - Xunlun Sheng
- Department of Ophthalmology, Ningxia Eye Hospital, People Hospital of Ningxia Hui Autonomous Region (First Affiliated Hospital of Northwest University for Nationalities), Yinchuan, China
| | - Yani Liu
- Department of Ophthalmology, Ningxia Eye Hospital, People Hospital of Ningxia Hui Autonomous Region (First Affiliated Hospital of Northwest University for Nationalities), Yinchuan, China
| | - Zili Li
- Department of Ophthalmology, Ningxia Eye Hospital, People Hospital of Ningxia Hui Autonomous Region (First Affiliated Hospital of Northwest University for Nationalities), Yinchuan, China
| | - Xiantao Sun
- Department of Ophthalmology, Children's Hospital of Zhengzhou, Zhengzhou, China
| | - Chao Jiang
- Department of Ophthalmology, State Key Laboratory of Reproductive Medicine, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Rui Qi
- Department of Ophthalmology, Ningxia Eye Hospital, People Hospital of Ningxia Hui Autonomous Region (First Affiliated Hospital of Northwest University for Nationalities), Yinchuan, China
| | - Shiqin Yuan
- Department of Ophthalmology, Ningxia Eye Hospital, People Hospital of Ningxia Hui Autonomous Region (First Affiliated Hospital of Northwest University for Nationalities), Yinchuan, China
| | - Xuhui Wang
- Department of Ophthalmology, Ningxia Eye Hospital, People Hospital of Ningxia Hui Autonomous Region (First Affiliated Hospital of Northwest University for Nationalities), Yinchuan, China
| | - Ge Zhou
- Department of Ophthalmology, Ningxia Eye Hospital, People Hospital of Ningxia Hui Autonomous Region (First Affiliated Hospital of Northwest University for Nationalities), Yinchuan, China
| | - Yanyan Zhen
- Department of Ophthalmology, Ningxia Eye Hospital, People Hospital of Ningxia Hui Autonomous Region (First Affiliated Hospital of Northwest University for Nationalities), Yinchuan, China
| | - Ping Xie
- Department of Ophthalmology, State Key Laboratory of Reproductive Medicine, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Qinghuai Liu
- Department of Ophthalmology, State Key Laboratory of Reproductive Medicine, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Biao Yan
- Department of Ophthalmology and Vision Science, Eye & ENT Hospital, Shanghai Medical College, Fudan University, Shanghai, China. .,Key Laboratory of Myopia of State Health Ministry (Fudan University) and Shanghai Key Laboratory of Visual Impairment and Restoration, Shanghai, China.
| | - Chen Zhao
- Department of Ophthalmology, State Key Laboratory of Reproductive Medicine, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China. .,Department of Ophthalmology and Vision Science, Eye & ENT Hospital, Shanghai Medical College, Fudan University, Shanghai, China. .,Key Laboratory of Myopia of State Health Ministry (Fudan University) and Shanghai Key Laboratory of Visual Impairment and Restoration, Shanghai, China. .,Department of Ophthalmology, Children's Hospital of Zhengzhou, Zhengzhou, China.
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26
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EYS Mutations Causing Autosomal Recessive Retinitis Pigmentosa: Changes of Retinal Structure and Function with Disease Progression. Genes (Basel) 2017; 8:genes8070178. [PMID: 28704921 PMCID: PMC5541311 DOI: 10.3390/genes8070178] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2017] [Revised: 07/06/2017] [Accepted: 07/06/2017] [Indexed: 11/24/2022] Open
Abstract
Mutations in the EYS (eyes shut homolog) gene are a common cause of autosomal recessive (ar) retinitis pigmentosa (RP). Without a mammalian model of human EYS disease, there is limited understanding of details of disease expression and rates of progression of the retinal degeneration. We studied clinically and with chromatic static perimetry, spectral-domain optical coherence tomography (OCT), and en face autofluoresence imaging, a cohort of 15 patients (ages 12–51 at first visit), some of whom had longitudinal data of function and structure. Rod sensitivity was able to be measured by chromatic perimetry in most patients at their earliest visits and some patients retained patchy rod function into the fifth decade of life. As expected from RP, cone sensitivity persisted after rod function was no longer measurable. The photoreceptor nuclear layer of the central retina was abnormal except at the fovea in most patients at first visit. Perifoveal disease measured over a period of years indicated that photoreceptor structural loss was followed by dysmorphology of the inner retina and loss of retinal pigment epithelial integrity. Although there could be variability in severity, preliminary analyses of the rates of vision loss suggested that EYS is a more rapidly progressive disease than other ciliopathies causing arRP, such as USH2A and MAK.
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27
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Jacobson SG, Cideciyan AV, Sumaroka A, Roman AJ, Charng J, Lu M, Choudhury S, Schwartz SB, Heon E, Fishman GA, Boye SE. Defining Outcomes for Clinical Trials of Leber Congenital Amaurosis Caused by GUCY2D Mutations. Am J Ophthalmol 2017; 177:44-57. [PMID: 28212877 DOI: 10.1016/j.ajo.2017.02.003] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2016] [Revised: 02/01/2017] [Accepted: 02/03/2017] [Indexed: 11/19/2022]
Abstract
PURPOSE To determine outcome measures for a clinical trial of Leber congenital amaurosis (LCA) associated with mutations in the GUCY2D gene. DESIGN Retrospective observational case series. METHODS Twenty-eight patients with GUCY2D-LCA (aged 2-59 years) were studied clinically and with chromatic full-field sensitivity testing (FST), optical coherence tomography (OCT), pupillometry, and the NEI Visual Function Questionnaire (VFQ). RESULTS FST permitted quantitation of cone and rod sensitivity in these patients with severe visual impairment. For most patients, the degree of rod and cone sensitivity losses showed a relationship, thereby providing an opportunity to divide patients into cohorts by severity of rod and cone dysfunction. OCT analyses indicated that retinal structure could be used not only as an objective safety measure but also as an exploratory efficacy outcome. A foveal bulge was not present in 67% of patients. The intensity of inner segment/outer segment (ellipsoid zone line) reflectivity was reduced significantly at the fovea and in the rod-dense superior retina. Based on OCT and FST parameters, most patients had dissociation of structure and function. Abnormal pupillometry sensitivity in the majority of GUCY2D-LCA patients provided another objective efficacy outcome. NEI VFQ scores showed a similar range of findings to those of other severe retinal diseases. CONCLUSION Conventional outcome measures, such as visual acuity and the NEI VFQ, will need to be complemented by methods more specific to this GUCY2D-LCA population. Any therapeutic strategy should determine if there is an effect on rod as well as cone function and structure. FST provides a photoreceptor-based subjective outcome; and OCT in 2 retinal regions, fovea and superior retina, can assess photoreceptor structure. A change in the relationship of structure and function away from baseline becomes evidence of efficacy.
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Affiliation(s)
- Samuel G Jacobson
- Scheie Eye Institute, Department of Ophthalmology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania.
| | - Artur V Cideciyan
- Scheie Eye Institute, Department of Ophthalmology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Alexander Sumaroka
- Scheie Eye Institute, Department of Ophthalmology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Alejandro J Roman
- Scheie Eye Institute, Department of Ophthalmology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Jason Charng
- Scheie Eye Institute, Department of Ophthalmology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Monica Lu
- Scheie Eye Institute, Department of Ophthalmology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Shreyasi Choudhury
- Department of Ophthalmology, College of Medicine, University of Florida, Gainesville, Florida
| | - Sharon B Schwartz
- Scheie Eye Institute, Department of Ophthalmology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Elise Heon
- Department of Ophthalmology and Vision Sciences, Program of Genetics and Genomic Biology, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
| | - Gerald A Fishman
- Pangere Center for Hereditary Retinal Diseases, The Chicago Lighthouse, Chicago, Illinois
| | - Shannon E Boye
- Department of Ophthalmology, College of Medicine, University of Florida, Gainesville, Florida
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28
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Coussa RG, Lopez Solache I, Koenekoop RK. Leber congenital amaurosis, from darkness to light: An ode to Irene Maumenee. Ophthalmic Genet 2017; 38:7-15. [PMID: 28095138 DOI: 10.1080/13816810.2016.1275021] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
This article is dedicated to Irene Hussels Maumenee, Professor of Human Genetics and Ophthalmology, Johns Hopkins' Wilmer Eye Institute, Ocular Genetics Fellowship director in 1994-1995. Leber congenital amaurosis (LCA) has almost come full circle, from a profound and molecularly uncharacterized form of congenital retinal blindness to one in which a large number of causative genes and disease pathways are known, and the world's first human retinal disease to be treated by gene therapy. Dr. Maumenee's insights, efforts, and leadership have contributed significantly to this remarkable scientific journey. In this manuscript, we present a short summary of the known LCA genes, LCA disease subtypes, and emerging treatment options. Our manuscript consolidates previous knowledge with current findings in an attempt to provide a more comprehensive understanding of LCA.
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Affiliation(s)
- Razek Georges Coussa
- a Department of Paediatric Surgery, Montreal Children's Hospital , McGill University Health Centre , Montreal , Quebec , Canada.,b The McGill Ocular Genetics Laboratory, Paediatric Ophthalmology Division , Montreal Children's Hospital, McGill University Health Centre , Montreal , Quebec , Canada
| | - Irma Lopez Solache
- b The McGill Ocular Genetics Laboratory, Paediatric Ophthalmology Division , Montreal Children's Hospital, McGill University Health Centre , Montreal , Quebec , Canada
| | - Robert K Koenekoop
- a Department of Paediatric Surgery, Montreal Children's Hospital , McGill University Health Centre , Montreal , Quebec , Canada.,b The McGill Ocular Genetics Laboratory, Paediatric Ophthalmology Division , Montreal Children's Hospital, McGill University Health Centre , Montreal , Quebec , Canada
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29
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Charng J, Cideciyan AV, Jacobson SG, Sumaroka A, Schwartz SB, Swider M, Roman AJ, Sheplock R, Anand M, Peden MC, Khanna H, Heon E, Wright AF, Swaroop A. Variegated yet non-random rod and cone photoreceptor disease patterns in RPGR-ORF15-associated retinal degeneration. Hum Mol Genet 2016; 25:5444-5459. [PMID: 27798110 PMCID: PMC6078602 DOI: 10.1093/hmg/ddw361] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Revised: 10/16/2016] [Accepted: 10/18/2016] [Indexed: 12/13/2022] Open
Abstract
Mutations in the ORF15 exon of the RPGR gene cause a common form of X-linked retinitis pigmentosa, which often results in severe loss of vision. In dogs and mice, gene augmentation therapy has been shown to arrest the progressive degeneration of rod and cone photoreceptors. However, the distribution of potentially treatable photoreceptors across the human retinas and the rate of degeneration are not known. Here, we have defined structural and functional features of the disease in 70 individuals with ORF15 mutations. We also correlated the features observed in patients with those of three Rpgr-mutant (Rpgr-ko, Rd9, and Rpgr-cko) mice. In patients, there was pronounced macular disease. Across the retina, rod and cone dysfunction showed a range of patterns and a spectrum of severity between individuals, but a high symmetry was observed between eyes of each individual. Genotype was not related to disease expression. In the Rpgr-ko mice, there were intra-retinal differences in rhodopsin and cone opsin trafficking. In Rd9 and Rpgr-cko mice, retinal degeneration showed inter-ocular symmetry. Longitudinal results in patients revealed localized rod and cone dysfunction with progression rates of 0.8 to 1.3 log per decade in sensitivity loss. Relatively retained rod and cone photoreceptors in mid- and far-peripheral temporal-inferior and nasal-inferior visual field regions should be good targets for future localized gene therapies in patients.
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Affiliation(s)
- Jason Charng
- Scheie Eye Institute, Department of Ophthalmology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, PA, USA
| | - Artur V. Cideciyan
- Scheie Eye Institute, Department of Ophthalmology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, PA, USA
| | - Samuel G. Jacobson
- Scheie Eye Institute, Department of Ophthalmology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, PA, USA
| | - Alexander Sumaroka
- Scheie Eye Institute, Department of Ophthalmology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, PA, USA
| | - Sharon B. Schwartz
- Scheie Eye Institute, Department of Ophthalmology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, PA, USA
| | - Malgorzata Swider
- Scheie Eye Institute, Department of Ophthalmology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, PA, USA
| | - Alejandro J. Roman
- Scheie Eye Institute, Department of Ophthalmology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, PA, USA
| | - Rebecca Sheplock
- Scheie Eye Institute, Department of Ophthalmology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, PA, USA
| | - Manisha Anand
- Department of Ophthalmology, University of Massachusetts Medical School, Worcester, Massachusetts, MA, USA
| | - Marc C. Peden
- Retina Associates of Florida, Tampa, Florida, FL, USA
| | - Hemant Khanna
- Department of Ophthalmology, University of Massachusetts Medical School, Worcester, Massachusetts, MA, USA
| | - Elise Heon
- Department of Ophthalmology and Vision Sciences, The Hospital for Sick Children, University of Toronto, Toronto, Canada
| | - Alan F. Wright
- MRC Human Genetics Unit, MRC IGMM, University of Edinburgh, Edinburgh, Scotland, UK
| | - Anand Swaroop
- Neurobiology-Neurodegeneration & Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, Maryland, MD, USA
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30
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Downs LM, Scott EM, Cideciyan AV, Iwabe S, Dufour V, Gardiner KL, Genini S, Marinho LF, Sumaroka A, Kosyk MS, Swider M, Aguirre GK, Jacobson SG, Beltran WA, Aguirre GD. Overlap of abnormal photoreceptor development and progressive degeneration in Leber congenital amaurosis caused by NPHP5 mutation. Hum Mol Genet 2016; 25:4211-4226. [PMID: 27506978 DOI: 10.1093/hmg/ddw254] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2016] [Revised: 07/14/2016] [Accepted: 07/21/2016] [Indexed: 01/11/2023] Open
Abstract
Ciliary defects can result in severe disorders called ciliopathies. Mutations in NPHP5 cause a ciliopathy characterized by severe childhood onset retinal blindness, Leber congenital amaurosis (LCA), and renal disease. Using the canine NPHP5-LCA model we compared human and canine retinal phenotypes, and examined the early stages of photoreceptor development and degeneration, the kinetics of photoreceptor loss, the progression of degeneration and the expression profiles of selected genes. NPHP5-mutant dogs recapitulate the human phenotype of very early loss of rods, and relative retention of the central retinal cone photoreceptors that lack function. In mutant dogs, rod and cone photoreceptors have a sensory cilium, but develop and function abnormally and then rapidly degenerate; L/M cones are more severely affected than S-cones. The lack of outer segments in mutant cones indicates a ciliary dysfunction. Genes expressed in mutant rod or both rod and cone photoreceptors show significant downregulation, while those expressed only in cones are unchanged. Many genes in cell-death and -survival pathways also are downregulated. The canine disease is a non-syndromic LCA-ciliopathy, with normal renal structures and no CNS abnormalities. Our results identify the critical time points in the pathogenesis of the photoreceptor disease, and bring us closer to defining a potential time window for testing novel therapies for translation to patients.
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Affiliation(s)
- Louise M Downs
- Section of Ophthalmology, Department of Clinical Studies, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Erin M Scott
- Section of Ophthalmology, Department of Clinical Studies, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Artur V Cideciyan
- Department of Ophthalmology, Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Simone Iwabe
- Section of Ophthalmology, Department of Clinical Studies, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Valerie Dufour
- Section of Ophthalmology, Department of Clinical Studies, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Kristin L Gardiner
- Section of Ophthalmology, Department of Clinical Studies, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Sem Genini
- Section of Ophthalmology, Department of Clinical Studies, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Luis Felipe Marinho
- Section of Ophthalmology, Department of Clinical Studies, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Alexander Sumaroka
- Department of Ophthalmology, Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Mychajlo S Kosyk
- Department of Ophthalmology, Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Malgorzata Swider
- Department of Ophthalmology, Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Geoffrey K Aguirre
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Samuel G Jacobson
- Department of Ophthalmology, Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - William A Beltran
- Section of Ophthalmology, Department of Clinical Studies, University of Pennsylvania, Philadelphia, PA 19104, USA,
| | - Gustavo D Aguirre
- Section of Ophthalmology, Department of Clinical Studies, University of Pennsylvania, Philadelphia, PA 19104, USA,
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Ullah I, Kabir F, Iqbal M, Gottsch CBS, Naeem MA, Assir MZ, Khan SN, Akram J, Riazuddin S, Ayyagari R, Hejtmancik JF, Riazuddin SA. Pathogenic mutations in TULP1 responsible for retinitis pigmentosa identified in consanguineous familial cases. Mol Vis 2016; 22:797-815. [PMID: 27440997 PMCID: PMC4947966] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2015] [Accepted: 07/14/2016] [Indexed: 11/16/2022] Open
Abstract
PURPOSE To identify pathogenic mutations responsible for autosomal recessive retinitis pigmentosa (arRP) in consanguineous familial cases. METHODS Seven large familial cases with multiple individuals diagnosed with retinitis pigmentosa were included in the study. Affected individuals in these families underwent ophthalmic examinations to document the symptoms and confirm the initial diagnosis. Blood samples were collected from all participating members, and genomic DNA was extracted. An exclusion analysis with microsatellite markers spanning the TULP1 locus on chromosome 6p was performed, and two-point logarithm of odds (LOD) scores were calculated. All coding exons along with the exon-intron boundaries of TULP1 were sequenced bidirectionally. We constructed a single nucleotide polymorphism (SNP) haplotype for the four familial cases harboring the K489R allele and estimated the likelihood of a founder effect. RESULTS The ophthalmic examinations of the affected individuals in these familial cases were suggestive of RP. Exclusion analyses confirmed linkage to chromosome 6p harboring TULP1 with positive two-point LOD scores. Subsequent Sanger sequencing identified the single base pair substitution in exon14, c.1466A>G (p.K489R), in four families. Additionally, we identified a two-base deletion in exon 4, c.286_287delGA (p.E96Gfs77*); a homozygous splice site variant in intron 14, c.1495+4A>C; and a novel missense variation in exon 15, c.1561C>T (p.P521S). All mutations segregated with the disease phenotype in the respective families and were absent in ethnically matched control chromosomes. Haplotype analysis suggested (p<10(-6)) that affected individuals inherited the causal mutation from a common ancestor. CONCLUSIONS Pathogenic mutations in TULP1 are responsible for the RP phenotype in seven familial cases with a common ancestral mutation responsible for the disease phenotype in four of the seven families.
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Affiliation(s)
- Inayat Ullah
- National Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
| | - Firoz Kabir
- The Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD
| | - Muhammad Iqbal
- National Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
| | | | - Muhammad Asif Naeem
- National Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
| | - Muhammad Zaman Assir
- Allama Iqbal Medical College, University of Health Sciences, Lahore, Pakistan,National Centre for Genetic Diseases, Shaheed Zulfiqar Ali Bhutto Medical University, Islamabad, Pakistan
| | - Shaheen N. Khan
- National Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
| | - Javed Akram
- Allama Iqbal Medical College, University of Health Sciences, Lahore, Pakistan,National Centre for Genetic Diseases, Shaheed Zulfiqar Ali Bhutto Medical University, Islamabad, Pakistan
| | - Sheikh Riazuddin
- National Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan,Allama Iqbal Medical College, University of Health Sciences, Lahore, Pakistan,National Centre for Genetic Diseases, Shaheed Zulfiqar Ali Bhutto Medical University, Islamabad, Pakistan
| | - Radha Ayyagari
- Shiley Eye Institute, University of California, San Diego, CA
| | - J. Fielding Hejtmancik
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, MD
| | - S. Amer Riazuddin
- The Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD
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A Novel Approach to Identify Photoreceptor Compartment-Specific Tulp1 Binding Partners. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 854:605-11. [PMID: 26427465 DOI: 10.1007/978-3-319-17121-0_80] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/22/2023]
Abstract
Photoreceptors (PRs) are highly polarized and compartmentalized cells with large amounts of proteins synthesized in the inner segment (IS) and transported to the outer segment (OS) and synaptic terminal. The PR-specific protein, Tulp1, is localized to the IS and synapse and is hypothesized to be involved in protein trafficking. To better understand the molecular processes that regulate protein trafficking in PRs, we aimed to identify compartment-specific Tulp1 binding partners. Serial tangential sectioning of Long Evans rat retinas was utilized to isolate the IS and synaptic PR compartments. Tulp1 binding partners in each of these layers were identified using co-immunoprecipitation (co-IP) with Tulp1 antibodies. The co-IP eluates were separated by SDS-PAGE, trypsinized into peptide fragments, and proteins were identified by liquid chromatography tandem mass spectrometry. In the IS, potential Tulp1-binding partners included cytoskeletal scaffold proteins, protein trafficking molecules, as well as members of the phototransduction cascade. In the synaptic region, the majority of interacting proteins identified were cytoskeletal. A separate subset of proteins were identified in both the IS and synapse including chaperones and family members of the GTPase activating proteins. Tulp1 has two distinct PR compartment-specific interactomes. Our results support the hypothesis that Tulp1 is involved in the trafficking of proteins from the IS to the OS and the continuous membrane remodeling and vesicle cycling at the synaptic terminal.
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Lobo GP, Au A, Kiser PD, Hagstrom SA. Involvement of Endoplasmic Reticulum Stress in TULP1 Induced Retinal Degeneration. PLoS One 2016; 11:e0151806. [PMID: 26987071 PMCID: PMC4795779 DOI: 10.1371/journal.pone.0151806] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2016] [Accepted: 03/04/2016] [Indexed: 11/18/2022] Open
Abstract
Inherited retinal disorders (IRDs) result in severe visual impairments in children and adults. A challenge in the field of retinal degenerations is identifying mechanisms of photoreceptor cell death related to specific genetic mutations. Mutations in the gene TULP1 have been associated with two forms of IRDs, early-onset retinitis pigmentosa (RP) and Leber congenital amaurosis (LCA). TULP1 is a cytoplasmic, membrane-associated protein shown to be involved in transportation of newly synthesized proteins destined for the outer segment compartment of photoreceptor cells; however, how mutant TULP1 causes cell death is not understood. In this study, we provide evidence that common missense mutations in TULP1 express as misfolded protein products that accumulate within the endoplasmic reticulum (ER) causing prolonged ER stress. In an effort to maintain protein homeostasis, photoreceptor cells then activate the unfolded protein response (UPR) complex. Our results indicate that the two major apoptotic arms of the UPR pathway, PERK and IRE1, are activated. Additionally, we show that retinas expressing mutant TULP1 significantly upregulate the expression of CHOP, a UPR signaling protein promoting apoptosis, and undergo photoreceptor cell death. Our study demonstrates that the ER-UPR, a known mechanism of apoptosis secondary to an overwhelming accumulation of misfolded protein, is involved in photoreceptor degeneration caused by missense mutations in TULP1. These observations suggest that modulating the UPR pathways might be a strategy for therapeutic intervention.
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Affiliation(s)
- Glenn P. Lobo
- Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio, 44195, United States of America
| | - Adrian Au
- Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio, 44195, United States of America
| | - Philip D. Kiser
- Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio, 44106, United States of America
- Louis Stokes Cleveland VA Medical Center, Cleveland, Ohio, 44106, United States of America
| | - Stephanie A. Hagstrom
- Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio, 44195, United States of America
- Department of Ophthalmology, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, Ohio, 44195, United States of America
- * E-mail:
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Matsui R, McGuigan Iii DB, Gruzensky ML, Aleman TS, Schwartz SB, Sumaroka A, Koenekoop RK, Cideciyan AV, Jacobson SG. SPATA7: Evolving phenotype from cone-rod dystrophy to retinitis pigmentosa. Ophthalmic Genet 2016; 37:333-8. [PMID: 26854980 DOI: 10.3109/13816810.2015.1130154] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
BACKGROUND SPATA7 mutations have been associated with different autosomal recessive retinal degeneration phenotypes. Long-term follow-up has not been described in detail. MATERIALS AND METHODS A Hispanic patient with SPATA7 mutations was evaluated serially over a 12-year period with kinetic and static chromatic perimetry, optical coherence tomography (OCT), and fundus autofluorescence (AF) imaging. Electroretinography (ERG) was performed at the initial visit. RESULTS The patient was homozygous for a mutation in SPATA7 (p.V458fs). At age 9, the ERG showed an abnormally reduced but preserved rod b-wave and no detectable cone signals. There were two islands of vision: a midperipheral island with greater cone than rod dysfunction and a central island with normal cone but no rod function. Serial measures of rod and cone vision and co-localized retinal structure showed that the midperipheral island slowly became undetectable. By age 21, only the central island and its cone function remained, but it had become more abnormal in structure and function. CONCLUSION The disease resulting from SPATA7 mutations in this patient initially presented as a cone-rod dystrophy (CRD), but changed over time into a phenotype more reminiscent of late-stage retinitis pigmentosa (RP). The differential diagnosis for both CRD and RP should include this rare molecular cause of autosomal retinal degeneration. An evolving phenotype complicates not only clinical diagnosis and patient counselling but also future strategies aimed at treating specific retinal regions.
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Affiliation(s)
- Rodrigo Matsui
- a Scheie Eye Institute, Department of Ophthalmology , Perelman School of Medicine at the University of Pennsylvania , Philadelphia , Pennsylvania , USA
| | - David B McGuigan Iii
- a Scheie Eye Institute, Department of Ophthalmology , Perelman School of Medicine at the University of Pennsylvania , Philadelphia , Pennsylvania , USA
| | - Michaela L Gruzensky
- a Scheie Eye Institute, Department of Ophthalmology , Perelman School of Medicine at the University of Pennsylvania , Philadelphia , Pennsylvania , USA
| | - Tomas S Aleman
- a Scheie Eye Institute, Department of Ophthalmology , Perelman School of Medicine at the University of Pennsylvania , Philadelphia , Pennsylvania , USA
| | - Sharon B Schwartz
- a Scheie Eye Institute, Department of Ophthalmology , Perelman School of Medicine at the University of Pennsylvania , Philadelphia , Pennsylvania , USA
| | - Alexander Sumaroka
- a Scheie Eye Institute, Department of Ophthalmology , Perelman School of Medicine at the University of Pennsylvania , Philadelphia , Pennsylvania , USA
| | - Robert K Koenekoop
- b McGill Ocular Genetics Laboratory (MOGL), Departments of Paediatric Surgery, Human Genetics, and Ophthalmology , Montreal Children's Hospital, McGill University Health Center , Montreal , Quebec , Canada
| | - Artur V Cideciyan
- a Scheie Eye Institute, Department of Ophthalmology , Perelman School of Medicine at the University of Pennsylvania , Philadelphia , Pennsylvania , USA
| | - Samuel G Jacobson
- a Scheie Eye Institute, Department of Ophthalmology , Perelman School of Medicine at the University of Pennsylvania , Philadelphia , Pennsylvania , USA
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Matsui R, Cideciyan AV, Schwartz SB, Sumaroka A, Roman AJ, Swider M, Huang WC, Sheplock R, Jacobson SG. Molecular Heterogeneity Within the Clinical Diagnosis of Pericentral Retinal Degeneration. Invest Ophthalmol Vis Sci 2016; 56:6007-18. [PMID: 26393467 DOI: 10.1167/iovs.15-17174] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE To characterize in detail the phenotype and genotype of patients with pericentral retinal degeneration (PRD). METHODS Patients were screened for an annular ring scotoma ranging from 3° to 40° (n = 28, ages 24-71) with kinetic perimetry. All patients had pigmentary retinopathy in the region of the dysfunction. Further studies included cross-sectional and en face imaging, static chromatic perimetry, and electroretinography. Molecular screening was performed. RESULTS Genotypes of 14 of 28 PRD patients were identified: There were mutations in eight different genes previously associated with autosomal dominant or autosomal recessive RDs. Kinetic fields monitored in some patients over years to more than a decade could be stable or show increased extent of the scotoma. Electroretinograms were recordable but with different severities of dysfunction. Patterns of photoreceptor outer nuclear layer (ONL) loss corresponded to the distribution of visual dysfunction. Outer nuclear layer thickness topography and en face imaging indicated that the greatest disease expression was in the area of known highest rod photoreceptor density. CONCLUSIONS Molecular heterogeneity was a feature of the PRD phenotype. Many of the molecular causes were also associated with other phenotypes, such as maculopathies, typical retinitis pigmentosa (RP) and cone-rod dystrophy. The pericentral pattern of retinal degeneration is thus confirmed to be an uncommon phenotype of many different genotypes rather than a distinct disease entity.
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Leber Congenital Amaurosis: Genotypes and Retinal Structure Phenotypes. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 854:169-75. [PMID: 26427408 DOI: 10.1007/978-3-319-17121-0_23] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Leber congenital amaurosis (LCA) patients of 10 known genotypes (n = 24; age range, 3-25 years) were studied clinically and by optical coherence tomography (OCT). Comparisons were made between OCT results across the horizontal meridian (central 60(o)) of the patients. Three patterns were identified. First, there were LCA genotypes with unusual and readily identifiable patterns, such as near normal outer nuclear layer (ONL) across the central retina or severely dysplastic retina. Second, there were genotypes with well-formed foveal architecture but only residual central islands of normal or reduced ONL thickness. Third, some genotypes showed central ONL losses or dysmorphology suggesting early macular disease or foveal maldevelopment. Objective in vivo morphological features could complement other phenotypic characteristics and help guide genetic testing of LCA patients or at least permit a differential diagnosis of genotypes to be made in the clinic.
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Cideciyan AV, Swider M, Jacobson SG. Autofluorescence imaging with near-infrared excitation:normalization by reflectance to reduce signal from choroidal fluorophores. Invest Ophthalmol Vis Sci 2015; 56:3393-406. [PMID: 26024124 DOI: 10.1167/iovs.15-16726] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE We previously developed reduced-illuminance autofluorescence imaging (RAFI) methods involving near-infrared (NIR) excitation to image melanin-based fluorophores and short-wavelength (SW) excitation to image lipofuscin-based flurophores. Here, we propose to normalize NIR-RAFI in order to increase the relative contribution of retinal pigment epithelium (RPE) fluorophores. METHODS Retinal imaging was performed with a standard protocol holding system parameters invariant in healthy subjects and in patients. Normalized NIR-RAFI was derived by dividing NIR-RAFI signal by NIR reflectance point-by-point after image registration. RESULTS Regions of RPE atrophy in Stargardt disease, AMD, retinitis pigmentosa, choroideremia, and Leber congenital amaurosis as defined by low signal on SW-RAFI could correspond to a wide range of signal on NIR-RAFI depending on the contribution from the choroidal component. Retinal pigment epithelium atrophy tended to always correspond to high signal on NIR reflectance. Normalizing NIR-RAFI reduced the choroidal component of the signal in regions of atrophy. Quantitative evaluation of RPE atrophy area showed no significant differences between SW-RAFI and normalized NIR-RAFI. CONCLUSIONS Imaging of RPE atrophy using lipofuscin-based AF imaging has become the gold standard. However, this technique involves bright SW lights that are uncomfortable and may accelerate the rate of disease progression in vulnerable retinas. The NIR-RAFI method developed here is a melanin-based alternative that is not absorbed by opsins and bisretinoid moieties, and is comfortable to view. Further development of this method may result in a nonmydriatic and comfortable imaging method to quantify RPE atrophy extent and its expansion rate.
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