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Yang Z, Yan L, Zhang W, Qi J, An W, Yao K. Dyschromatopsia: a comprehensive analysis of mechanisms and cutting-edge treatments for color vision deficiency. Front Neurosci 2024; 18:1265630. [PMID: 38298913 PMCID: PMC10828017 DOI: 10.3389/fnins.2024.1265630] [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: 07/23/2023] [Accepted: 01/02/2024] [Indexed: 02/02/2024] Open
Abstract
Color blindness is a retinal disease that mainly manifests as a color vision disorder, characterized by achromatopsia, red-green color blindness, and blue-yellow color blindness. With the development of technology and progress in theory, extensive research has been conducted on the genetic basis of color blindness, and various approaches have been explored for its treatment. This article aims to provide a comprehensive review of recent advances in understanding the pathological mechanism, clinical symptoms, and treatment options for color blindness. Additionally, we discuss the various treatment approaches that have been developed to address color blindness, including gene therapy, pharmacological interventions, and visual aids. Furthermore, we highlight the promising results from clinical trials of these treatments, as well as the ongoing challenges that must be addressed to achieve effective and long-lasting therapeutic outcomes. Overall, this review provides valuable insights into the current state of research on color blindness, with the intention of informing further investigation and development of effective treatments for this disease.
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Affiliation(s)
- Zihao Yang
- Institute of Visual Neuroscience and Stem Cell Engineering, Wuhan University of Science and Technology, Wuhan, China
- College of Life Sciences and Health, Wuhan University of Science and Technology, Wuhan, China
| | - Lin Yan
- Institute of Visual Neuroscience and Stem Cell Engineering, Wuhan University of Science and Technology, Wuhan, China
- College of Life Sciences and Health, Wuhan University of Science and Technology, Wuhan, China
| | - Wenliang Zhang
- Institute of Visual Neuroscience and Stem Cell Engineering, Wuhan University of Science and Technology, Wuhan, China
- College of Life Sciences and Health, Wuhan University of Science and Technology, Wuhan, China
| | - Jia Qi
- Institute of Visual Neuroscience and Stem Cell Engineering, Wuhan University of Science and Technology, Wuhan, China
- College of Life Sciences and Health, Wuhan University of Science and Technology, Wuhan, China
| | - Wenjing An
- Institute of Visual Neuroscience and Stem Cell Engineering, Wuhan University of Science and Technology, Wuhan, China
- College of Life Sciences and Health, Wuhan University of Science and Technology, Wuhan, China
| | - Kai Yao
- Institute of Visual Neuroscience and Stem Cell Engineering, Wuhan University of Science and Technology, Wuhan, China
- College of Life Sciences and Health, Wuhan University of Science and Technology, Wuhan, China
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Danish E, Alhashem A, Aljehani R, Aljawi A, Aldarwish MM, Al Mutairi F, Alfadhel M, Alrifai MT, Alobaisi S. Phenotype and genotype of 15 Saudi patients with achromatopsia: A case series. Saudi J Ophthalmol 2023; 37:301-306. [PMID: 38155673 PMCID: PMC10752271 DOI: 10.4103/sjopt.sjopt_108_23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Revised: 07/23/2023] [Accepted: 07/27/2023] [Indexed: 12/30/2023] Open
Abstract
PURPOSE Achromatopsia is a rare stationary retinal disorder that primarily affects the cone photoreceptors. Individuals with achromatopsia present with photophobia, nystagmus, reduced visual acuity (VA), and color blindness. Multiple genes responsible for achromatopsia have been identified (e.g. cyclic nucleotide-gated channel subunit alpha 3 [CNGA3] and activating transcription factor 6). Studies have assessed the role of gene therapy in achromatopsia. Therefore, for treatment and prevention, the identification of phenotypes and genotypes is crucial. Here, we described the clinical manifestations and genetic mutations associated with achromatopsia in patients from Saudi Arabia. METHODS This case series study included 15 patients with clinical presentations, suggestive of achromatopsia, who underwent ophthalmological and systemic evaluations. Patients with typical achromatopsia phenotype underwent genetic evaluation using whole-exome testing. RESULTS All patients had nystagmus (n = 15) and 93.3% had photophobia (n = 14). In addition, all patients (n = 15) had poor VA. Hyperopia with astigmatism was observed in 93.3% (n = 14) and complete color blindness in 93.3% of the patients (n = 14). In the context of family history, both parents of all patients (n = 15) were genetic carriers, with a high consanguinity rate (82%, n = 9 families). Electroretinography showed cone dysfunction with normal rods in 66.7% (n = 10) and both cone-rod dysfunction in 33.3% (n = 5) patients. Regarding the genotypic features, 93% of patients had variants in CNGA3 (n = 14) categorized as pathogenic Class 1 (86.7%, n = 13). Further, 66.7% (n = 10) of patients also harbored the c.661C>T DNA variant. Further, the patients were homozygous for these mutations. Three other variants were also identified: c.1768G>A (13.3%, n = 2), c.830G>A (6.6%, n = 1), and c. 822G >T (6.6%, n = 1). CONCLUSION Consanguinity and belonging to the same tribe are major risk factors for disease inheritance. The most common genotype was CNGA3 with the c.661C>T DNA variant. We recommend raising awareness among families and providing genetic counseling for this highly debilitating disease.
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Affiliation(s)
- Enam Danish
- Department of Ophthalmology, King Fahad Armed Forces Hospital, Jeddah, Saudi Arabia
| | - Amal Alhashem
- Department of Pediatric, Division of Genetic and Metabolic Medicine, Prince Sultan Medical Military City, College of Medicine, Alfaisal University, Riyadh, Saudi Arabia
| | - Reham Aljehani
- Department of Ophthalmology, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Anan Aljawi
- Department of Ophthalmology, King Abdulaziz Medical City, Jeddah, Saudi Arabia
| | - Manar M. Aldarwish
- Department of Genetics and Precision Medicine, King Abdullah Specialized Children Hospital, King Abdulaziz Medical City, Ministry of National Guard Health Affairs, Riyadh, Saudi Arabia
| | - Fuad Al Mutairi
- Department of Genetics and Precision Medicine, King Abdullah Specialized Children Hospital, King Abdulaziz Medical City, Ministry of National Guard Health Affairs, Riyadh, Saudi Arabia
- King Abdullah International Medical Research Centre, Ministry of National Guard Health Affairs, King Saud Bin Abdulaziz University for Health Sciences, Riyadh, Saudi Arabia
| | - Majid Alfadhel
- Department of Genetics and Precision Medicine, King Abdullah Specialized Children Hospital, King Abdulaziz Medical City, Ministry of National Guard Health Affairs, Riyadh, Saudi Arabia
- Department of Medical Genomics Research, King Abdullah International Medical Research Center, Ministry of National Guard Health Affairs, King Saud Bin Abdulaziz University for Health Sciences, Riyadh, Saudi Arabia
| | - Muhammad T. Alrifai
- King Abdullah International Medical Research Centre, Ministry of National Guard Health Affairs, King Saud Bin Abdulaziz University for Health Sciences, Riyadh, Saudi Arabia
- Pediatric Ophthalmology Division, Department of Pediatric Surgery, King Abdullah Specialized Children Hospital, King Abdulaziz Medical City, Ministry of National Guard Health Affairs, Riyadh, Saudi Arabia
| | - Saif Alobaisi
- Pediatric Ophthalmology Division, Department of Pediatric Surgery, King Abdullah Specialized Children Hospital, King Abdulaziz Medical City, Ministry of National Guard Health Affairs, Riyadh, Saudi Arabia
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Käsmann-Kellner B, Hoffmann MB. [Achromatopsia : Clinical aspects, diagnostics, genes, brain and quality of life]. DIE OPHTHALMOLOGIE 2023; 120:975-986. [PMID: 37638972 DOI: 10.1007/s00347-023-01904-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 07/14/2023] [Indexed: 08/29/2023]
Abstract
Achromatopsia or rod monochromatism is a congenital autosomal recessive retinal dystrophy which leads to dysfunctional cones, with decreased visual acuity, extremely limited color vision, nystagmus and photophobia. Due to the initially normally appearing ocular morphology, the diagnosis is often delayed. With imaging procedures, e.g., fluorescence-autofluorescence (FAF) and optical coherence tomography (OCT), different morphological forms of achromatopsia can be discriminated that do not seem to have a differential effect on visual function. Crucial is the provision of specific edge filters. Mutations in six genes are known to cause achromatopsia. For the two most frequent genes, CNGA3 and CNGB3, gene addition therapies are currently being tested. Such future approaches should be applied before the manifestation of sensory-related amblyopia in the visual cortex. Accordingly, state of the art management of achromatopsia should provide a diagnosis in early childhood including genotyping.
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Affiliation(s)
- Barbara Käsmann-Kellner
- Klinik für Augenheilkunde, Sektion KiOLoN: Kinderophthalmologie, Orthoptik, Low Vision und Neuroophthalmologie, Universitätsklinikum des Saarlandes UKS, Kirrbergerstr. 100, 66421, Homburg/Saar, Deutschland.
| | - Michael B Hoffmann
- Universitäts-Augenklinik Magdeburg, Magdeburg, Deutschland
- Center for Behavioral Brain Sciences, Magdeburg, Deutschland
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Lowndes R, Molz B, Warriner L, Herbik A, de Best PB, Raz N, Gouws A, Ahmadi K, McLean RJ, Gottlob I, Kohl S, Choritz L, Maguire J, Kanowski M, Käsmann-Kellner B, Wieland I, Banin E, Levin N, Hoffmann MB, Morland AB, Baseler HA. Structural Differences Across Multiple Visual Cortical Regions in the Absence of Cone Function in Congenital Achromatopsia. Front Neurosci 2021; 15:718958. [PMID: 34720857 PMCID: PMC8551799 DOI: 10.3389/fnins.2021.718958] [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: 06/01/2021] [Accepted: 09/16/2021] [Indexed: 11/13/2022] Open
Abstract
Most individuals with congenital achromatopsia (ACHM) carry mutations that affect the retinal phototransduction pathway of cone photoreceptors, fundamental to both high acuity vision and colour perception. As the central fovea is occupied solely by cones, achromats have an absence of retinal input to the visual cortex and a small central area of blindness. Additionally, those with complete ACHM have no colour perception, and colour processing regions of the ventral cortex also lack typical chromatic signals from the cones. This study examined the cortical morphology (grey matter volume, cortical thickness, and cortical surface area) of multiple visual cortical regions in ACHM (n = 15) compared to normally sighted controls (n = 42) to determine the cortical changes that are associated with the retinal characteristics of ACHM. Surface-based morphometry was applied to T1-weighted MRI in atlas-defined early, ventral and dorsal visual regions of interest. Reduced grey matter volume in V1, V2, V3, and V4 was found in ACHM compared to controls, driven by a reduction in cortical surface area as there was no significant reduction in cortical thickness. Cortical surface area (but not thickness) was reduced in a wide range of areas (V1, V2, V3, TO1, V4, and LO1). Reduction in early visual areas with large foveal representations (V1, V2, and V3) suggests that the lack of foveal input to the visual cortex was a major driving factor in morphological changes in ACHM. However, the significant reduction in ventral area V4 coupled with the lack of difference in dorsal areas V3a and V3b suggest that deprivation of chromatic signals to visual cortex in ACHM may also contribute to changes in cortical morphology. This research shows that the congenital lack of cone input to the visual cortex can lead to widespread structural changes across multiple visual areas.
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Affiliation(s)
- Rebecca Lowndes
- Department of Psychology, University of York, York, United Kingdom
- York Neuroimaging Centre, Department of Psychology, University of York, York, United Kingdom
| | - Barbara Molz
- Department of Psychology, University of York, York, United Kingdom
- Language and Genetics Department, Max Planck Institute for Psycholinguistics, Nijmegen, Netherlands
| | - Lucy Warriner
- Department of Psychology, University of York, York, United Kingdom
| | - Anne Herbik
- Department of Ophthalmology, University Hospital, Otto von Guericke University, Magdeburg, Germany
| | - Pieter B. de Best
- MRI Unit, Department of Neurology, Hadassah Medical Center, Jerusalem, Israel
| | - Noa Raz
- MRI Unit, Department of Neurology, Hadassah Medical Center, Jerusalem, Israel
| | - Andre Gouws
- York Neuroimaging Centre, Department of Psychology, University of York, York, United Kingdom
| | - Khazar Ahmadi
- Department of Ophthalmology, University Hospital, Otto von Guericke University, Magdeburg, Germany
| | - Rebecca J. McLean
- University of Leicester Ulverscroft Eye Unit, University of Leicester, Leicester Royal Infirmary, Leicester, United Kingdom
| | - Irene Gottlob
- University of Leicester Ulverscroft Eye Unit, University of Leicester, Leicester Royal Infirmary, Leicester, United Kingdom
| | - Susanne Kohl
- Molecular Genetics Laboratory, Institute for Ophthalmic Research, Centre for Ophthalmology, University Clinics Tübingen, Tübingen, Germany
| | - Lars Choritz
- Department of Ophthalmology, University Hospital, Otto von Guericke University, Magdeburg, Germany
| | - John Maguire
- School of Optometry and Vision Sciences, University of Bradford, Bradford, United Kingdom
| | - Martin Kanowski
- Department of Neurology, University Hospital, Otto von Guericke University, Magdeburg, Germany
| | - Barbara Käsmann-Kellner
- Department of Ophthalmology, Saarland University Hospital and Medical Faculty of the Saarland University Hospital, Homburg, Germany
| | - Ilse Wieland
- Department of Molecular Genetics, Institute for Human Genetics, University Hospital, Otto von Guericke University, Magdeburg, Germany
| | - Eyal Banin
- Degenerative Diseases of the Retina Unit, Department of Ophthalmology, Hadassah Medical Center, Jerusalem, Israel
| | - Netta Levin
- MRI Unit, Department of Neurology, Hadassah Medical Center, Jerusalem, Israel
| | - Michael B. Hoffmann
- Department of Ophthalmology, University Hospital, Otto von Guericke University, Magdeburg, Germany
- Center for Behavioral Brain Sciences, Magdeburg, Germany
| | - Antony B. Morland
- Department of Psychology, University of York, York, United Kingdom
- York Biomedical Research Institute, University of York, York, United Kingdom
| | - Heidi A. Baseler
- Department of Psychology, University of York, York, United Kingdom
- York Biomedical Research Institute, University of York, York, United Kingdom
- Hull York Medical School, University of York, York, United Kingdom
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