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Nowińska A, Chlasta-Twardzik E, Dembski M, Wróblewska-Czajka E, Ulfik-Dembska K, Wylęgała E. Detailed corneal and genetic characteristics of a pediatric patient with macular corneal dystrophy - case report. BMC Ophthalmol 2021; 21:285. [PMID: 34301210 PMCID: PMC8299585 DOI: 10.1186/s12886-021-02041-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Accepted: 07/07/2021] [Indexed: 11/08/2023] Open
Abstract
BACKGROUND Corneal dystrophies are a group of rare, inherited disorders that are usually bilateral, symmetric, slowly progressive, and not related to environmental or systemic factors. The majority of publications present the advanced form of the disease with a typical clinical demonstration. The initial signs and symptoms of different epithelial and stromal corneal dystrophies are not specific; therefore, it is very important to establish the early characteristic corneal features of these disorders that could guide the diagnostic process. CASE PRESENTATION The main purpose of this study was to report the differential diagnosis of a pediatric patient with bilateral anterior corneal involvement suspected of corneal dystrophy. An 8-year-old male patient presented with asymptomatic, persistent, superficial, bilateral, diffuse, anterior corneal opacities. Slit lamp examination results were not specific. Despite the lack of visible stromal involvement on the slit lamp examination, corneal analysis based on confocal microscopy and optical coherence tomography revealed characteristic features of macular corneal dystrophy (MCD). The diagnosis of MCD was confirmed by CHST6 gene sequencing. The early corneal characteristic features of MCD, established based on the findings of this case report, include corneal astigmatism (not specific), diffuse corneal thinning without a pattern of corneal ectasia (specific), and characteristic features on confocal microscopy (specific), including multiple, dark, oriented striae at different corneal depths. CONCLUSIONS The clinical examination should be complemented with corneal imaging techniques, such as confocal microscopy and optical coherence tomography. In patients suspected of corneal dystrophy, genetic testing plays an important role in establishing the final diagnosis.
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Affiliation(s)
- Anna Nowińska
- Chair and Clinical Department of Ophthalmology, Faculty of Medical Sciences in Zabrze, Medical University of Silesia in Katowice, ul. Panewnicka 65, 40-760, Katowice, Poland.
- Ophthalmology Department, Railway Hospital in Katowice, Katowice, Poland.
| | - Edyta Chlasta-Twardzik
- Chair and Clinical Department of Ophthalmology, Faculty of Medical Sciences in Zabrze, Medical University of Silesia in Katowice, ul. Panewnicka 65, 40-760, Katowice, Poland
- Ophthalmology Department, Railway Hospital in Katowice, Katowice, Poland
| | - Michał Dembski
- Chair and Clinical Department of Ophthalmology, Faculty of Medical Sciences in Zabrze, Medical University of Silesia in Katowice, ul. Panewnicka 65, 40-760, Katowice, Poland
- Ophthalmology Department, Railway Hospital in Katowice, Katowice, Poland
| | - Ewa Wróblewska-Czajka
- Chair and Clinical Department of Ophthalmology, Faculty of Medical Sciences in Zabrze, Medical University of Silesia in Katowice, ul. Panewnicka 65, 40-760, Katowice, Poland
- Ophthalmology Department, Railway Hospital in Katowice, Katowice, Poland
| | - Klaudia Ulfik-Dembska
- Chair and Clinical Department of Ophthalmology, Faculty of Medical Sciences in Zabrze, Medical University of Silesia in Katowice, ul. Panewnicka 65, 40-760, Katowice, Poland
- Ophthalmology Department, Railway Hospital in Katowice, Katowice, Poland
| | - Edward Wylęgała
- Chair and Clinical Department of Ophthalmology, Faculty of Medical Sciences in Zabrze, Medical University of Silesia in Katowice, ul. Panewnicka 65, 40-760, Katowice, Poland
- Ophthalmology Department, Railway Hospital in Katowice, Katowice, Poland
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Safari I, Baradaran-Rafii A, Issazadeh-Navikas S, Elahi E. CHST6 mutations identified in Iranian MCD patients and CHST6 mutations reported worldwide identify targets for gene editing approaches including the CRISPR/Cas system. Int Ophthalmol 2020; 40:2223-2235. [PMID: 32472422 DOI: 10.1007/s10792-020-01401-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Accepted: 04/25/2020] [Indexed: 12/19/2022]
Abstract
PURPOSE To identify CHST6 mutations in Iranians macular corneal dystrophy (MCD) patients and also to assess distribution of amino acids in the encoded protein that are affected by CHST6 mutations reported hitherto in various populations in order to predict gene regions that may be appropriate targets for gene editing approaches including the CRISPR/Cas system. The analysis will also reveal biologically and functionally important regions of the protein. METHODS Mutation screening of CHST6 by sequencing was performed on 21 Iranian MCD-affected probands. Previously reported MCD causing CHST6 mutations were identified by searches in NCBI. RESULTS Nineteen CHST6 mutations were found among the 21 Iranian patients, most of which were missense mutations and six of which were novel. Totally, 189 mutations among 375 MCD patients have been found worldwide, and 134 of these are missense mutations. The distribution of 88 amino acids affected by missense mutations along the length of the encoded protein was not random, and four regions of possible mutation clustering were noted. 25% of patients harbored mutations in a DNA region consisting of only 36 nucleotides. CONCLUSION Similar to most populations, CHST6 mutations among Iranians are very heterogeneous as indicated by finding 19 different mutations among 21 MCD patients. Nevertheless, identification of four potential mutation clusters identifies regions that are most suitable for gene therapy targeting by the CRISPR/Cas approach. Additionally, the mutation clusters identify regions with potential structural and/or functional importance. Consistent with this, the amino acids in these regions are well conserved among various membrane-bound sulfotransferases.
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Affiliation(s)
- Iman Safari
- School of Biology, University College of Science, University of Tehran, Enghelab Ave, Tehran, 1417614411, Iran
| | | | - Shohreh Issazadeh-Navikas
- Neuroinflammation Unit, Biotech Research and Innovation Centre (BRIC), University of Copenhagen, Copenhagen, Denmark
| | - Elahe Elahi
- School of Biology, University College of Science, University of Tehran, Enghelab Ave, Tehran, 1417614411, Iran.
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Zhang J, Wu D, Li Y, Fan Y, Dai Y, Xu J. A comprehensive evaluation of 181 reported CHST6 variants in patients with macular corneal dystrophy. Aging (Albany NY) 2019; 11:1019-1029. [PMID: 30716718 PMCID: PMC6382428 DOI: 10.18632/aging.101807] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2018] [Accepted: 01/25/2019] [Indexed: 01/16/2023]
Abstract
Macular corneal dystrophy (MCD) is an autosomal recessive disease featured by bilateral progressive stromal clouding and loss of vision, consequently necessitating corneal transplantation. Variants in CHST6 gene have been recognized as the most critical genetic components in MCD. Although many CHST6 variants have been described until now, the detailed mechanisms underlying MCD are still far from understood. In this study, we integrated all the reported CHST6 variants described in 408 MCD cases, and performed a comprehensive evaluation to better illustrate the causality of these variants. The results showed that majority of these variants (165 out of 181) could be classified as pathogenic or likely pathogenic. Interestingly, we also identified several disease causal variants with ethnic specificity. In addition, the results underscored the strong correlation between mutant frequency and residue conservation in the general population (Spearman's correlation coefficient = -0.311, P = 1.20E-05), thus providing potential candidate targets for further genetic manipulation. The current study highlighted the demand of further functional investigations to evaluate the causality of CHST6 variants, so as to promote earlier accurate diagnosis of MCD and future development of potential targets for genetic therapy.
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Affiliation(s)
- Jing Zhang
- Department of Ophthalmology and Visual Science, Eye Institute, Eye and ENT Hospital, Shanghai Medical College of Fudan University, NHC Key Laboratory of Myopia (Fudan University), Shanghai Key Laboratory of Visual Impairment and Restoration, Shanghai, China
| | - Dan Wu
- Department of Ophthalmology and Visual Science, Eye Institute, Eye and ENT Hospital, Shanghai Medical College of Fudan University, NHC Key Laboratory of Myopia (Fudan University), Shanghai Key Laboratory of Visual Impairment and Restoration, Shanghai, China
| | - Yue Li
- Department of Ophthalmology and Visual Science, Eye Institute, Eye and ENT Hospital, Shanghai Medical College of Fudan University, NHC Key Laboratory of Myopia (Fudan University), Shanghai Key Laboratory of Visual Impairment and Restoration, Shanghai, China
| | - Yidan Fan
- Department of Ophthalmology and Visual Science, Eye Institute, Eye and ENT Hospital, Shanghai Medical College of Fudan University, NHC Key Laboratory of Myopia (Fudan University), Shanghai Key Laboratory of Visual Impairment and Restoration, Shanghai, China
| | - Yiqin Dai
- Department of Ophthalmology and Visual Science, Eye Institute, Eye and ENT Hospital, Shanghai Medical College of Fudan University, NHC Key Laboratory of Myopia (Fudan University), Shanghai Key Laboratory of Visual Impairment and Restoration, Shanghai, China
| | - Jianjiang Xu
- Department of Ophthalmology and Visual Science, Eye Institute, Eye and ENT Hospital, Shanghai Medical College of Fudan University, NHC Key Laboratory of Myopia (Fudan University), Shanghai Key Laboratory of Visual Impairment and Restoration, Shanghai, China
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Aggarwal S, Peck T, Golen J, Karcioglu ZA. Macular corneal dystrophy: A review. Surv Ophthalmol 2018; 63:609-617. [DOI: 10.1016/j.survophthal.2018.03.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2017] [Revised: 03/19/2018] [Accepted: 03/21/2018] [Indexed: 10/17/2022]
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Caterson B, Melrose J. Keratan sulfate, a complex glycosaminoglycan with unique functional capability. Glycobiology 2018; 28:182-206. [PMID: 29340594 PMCID: PMC5993099 DOI: 10.1093/glycob/cwy003] [Citation(s) in RCA: 139] [Impact Index Per Article: 23.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2017] [Revised: 12/20/2017] [Accepted: 01/08/2018] [Indexed: 12/19/2022] Open
Abstract
From an evolutionary perspective keratan sulfate (KS) is the newest glycosaminoglycan (GAG) but the least understood. KS is a sophisticated molecule with a diverse structure, and unique functional roles continue to be uncovered for this GAG. The cornea is the richest tissue source of KS in the human body but the central and peripheral nervous systems also contain significant levels of KS and a diverse range of KS-proteoglycans with essential functional roles. KS also displays important cell regulatory properties in epithelial and mesenchymal tissues and in bone and in tumor development of diagnostic and prognostic utility. Corneal KS-I displays variable degrees of sulfation along the KS chain ranging from non-sulfated polylactosamine, mono-sulfated and disulfated disaccharide regions. Skeletal KS-II is almost completely sulfated consisting of disulfated disaccharides interrupted by occasional mono-sulfated N-acetyllactosamine residues. KS-III also contains highly sulfated KS disaccharides but differs from KS-I and KS-II through 2-O-mannose linkage to serine or threonine core protein residues on proteoglycans such as phosphacan and abakan in brain tissue. Historically, the major emphasis on the biology of KS has focused on its sulfated regions for good reason. The sulfation motifs on KS convey important molecular recognition information and direct cell behavior through a number of interactive proteins. Emerging evidence also suggest functional roles for the poly-N-acetyllactosamine regions of KS requiring further investigation. Thus further research is warranted to better understand the complexities of KS.
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Affiliation(s)
- Bruce Caterson
- Connective Tissue Biology Laboratories, School of Biosciences, College of Biological & Life Sciences, Cardiff University, Cardiff, Wales, UK
| | - James Melrose
- Raymond Purves Bone and Joint Research Laboratory, Kolling Institute of Medical Research, Northern Sydney Local Health District, St. Leonards, NSW, Australia
- Sydney Medical School, Northern, The University of Sydney, Royal North Shore Hospital, St. Leonards, NSW, Australia
- Graduate School of Biomedical Engineering, University of New South Wales, Sydney, NSW, Australia
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Dudakova L, Palos M, Svobodova M, Bydzovsky J, Huna L, Jirsova K, Hardcastle AJ, Tuft SJ, Liskova P. Macular corneal dystrophy and associated corneal thinning. Eye (Lond) 2014; 28:1201-5. [PMID: 25081284 PMCID: PMC4194335 DOI: 10.1038/eye.2014.164] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2013] [Accepted: 05/31/2014] [Indexed: 11/08/2022] Open
Abstract
PURPOSE To identify the molecular genetic cause of macular corneal dystrophy (MCD) in four probands, and characterize phenotypic similarities between MCD and keratoconus. METHODS We performed ophthalmological examination, Scheimpflug imaging (Pentacam, Oculus Inc.), histopathological examination of excised corneal buttons, and direct sequencing of the CHST6 coding region. RESULTS Pentacam measurements were taken in six eyes of three probands. All showed diffuse corneal thinning with paracentral steepening of the anterior corneal surface that was graded as keratoconus by the integrated software, but without associated ectasia of the posterior corneal surface or regional thinning. Homozygous or compound heterozygous CHST6 mutations were identified in all cases, including two novel mutations, c.13C>T; p.(Arg5Cys) and c.289C>T; p.(Arg97Cys). DISCUSSION Localized elevation of the anterior corneal curvature can occur in MCD in the absence of other features of keratoconus. The identification of a further two Czech probands with the compound allele c.[484C>G; 599T>G] supports the enrichment of this allele in the study population.
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Affiliation(s)
- L Dudakova
- Laboratory of the Biology and Pathology of the Eye, Institute of Inherited Metabolic Disorders, First Faculty of Medicine, Charles University in Prague and General University Hospital in Prague, Prague, Czech Republic
| | - M Palos
- Department of Ophthalmology, First Faculty of Medicine, Charles University in Prague and General University Hospital in Prague, Prague, Czech Republic
| | - M Svobodova
- Department of Ophthalmology, First Faculty of Medicine, Charles University in Prague and General University Hospital in Prague, Prague, Czech Republic
| | - J Bydzovsky
- Department of Ophthalmology, First Faculty of Medicine, Charles University in Prague and General University Hospital in Prague, Prague, Czech Republic
| | - L Huna
- Department of Ophthalmology, First Faculty of Medicine, Charles University in Prague and General University Hospital in Prague, Prague, Czech Republic
| | - K Jirsova
- Laboratory of the Biology and Pathology of the Eye, Institute of Inherited Metabolic Disorders, First Faculty of Medicine, Charles University in Prague and General University Hospital in Prague, Prague, Czech Republic
| | - A J Hardcastle
- Department of Ocular Biology and Therapeutics, UCL Institute of Ophthalmology, London, UK
| | - S J Tuft
- Department of Ocular Biology and Therapeutics, UCL Institute of Ophthalmology, London, UK
- Corneal Service, Moorfields Eye Hospital NHS Foundation Trust, London, UK
| | - P Liskova
- Laboratory of the Biology and Pathology of the Eye, Institute of Inherited Metabolic Disorders, First Faculty of Medicine, Charles University in Prague and General University Hospital in Prague, Prague, Czech Republic
- Department of Ophthalmology, First Faculty of Medicine, Charles University in Prague and General University Hospital in Prague, Prague, Czech Republic
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Palka BP, Sotozono C, Tanioka H, Akama TO, Yagi N, Boote C, Young RD, Meek KM, Kinoshita S, Quantock AJ. Structural collagen alterations in macular corneal dystrophy occur mainly in the posterior stroma. Curr Eye Res 2010; 35:580-6. [PMID: 20597644 DOI: 10.3109/02713681003760150] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
PURPOSE Collagen fibrils in the corneal stroma in macular corneal dystrophy, on average, are more closely spaced than in the normal cornea. This study was conducted to investigate if this occurs uniformly across the stroma or is more prevalent at certain stromal depths. METHODS Microbeam synchrotron X-ray fiber diffraction patterns were obtained in 25 microm steps across the whole thickness of a thin strip of a macular corneal dystrophy cornea obtained at keratoplasty. Data were analyzed for mean collagen interfibrillar spacing at all positions. Serum was analyzed immunochemically to determine immunophenotype, and transmission electron microscopy was carried out to visualize stromal ultrastructure. RESULTS Keratan sulphate was not detectable in blood serum, classifying the disease as macular corneal dystrophy type I. Collagen interfibrillar spacing dropped linearly with stromal depth from the anterior to posterior cornea, measuring 5-10% less in the posterior 100 microm of the MCD stroma compared to the anterior 100 microm (p < 0.001). Isolated pockets of collagen fibrils with unusually large diameters were identified in the deep stroma. CONCLUSIONS Collagen fibril spacing is reduced and large-diameter collagen fibrils are seen in macular corneal dystrophy type I, with the deep stroma affected more. We speculate that the ultrastructural abnormalities are more prevalent in the posterior stroma because the structural influence of sulphated keratan sulphate glycosaminoglycans/proteoglycans is high in this region of the cornea.
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Affiliation(s)
- Barbara P Palka
- School of Optometry & Vision Sciences, Cardiff University, Cardiff, United Kingdom
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Liu Z, Tian X, Iida N, Fujiki K, Xie P, Wang W, Ma Z, Kanai A, Murakami A. Mutation analysis of CHST6 gene in Chinese patients with macular corneal dystrophy. Cornea 2010; 29:883-8. [PMID: 20539220 DOI: 10.1097/ico.0b013e3181ca2e74] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE To examine the carbohydrate sulfotransferase 6 (CHST6) gene in Chinese patients with macular corneal dystrophy (MCD). METHODS Nineteen unrelated Chinese families with MCD, including 24 patients and 3 unaffected relatives, were examined. Genomic DNA was extracted from peripheral blood leukocytes. The coding region of the CHST6 gene was amplified by the polymerase chain reaction, and the DNA fragments were directly sequenced. Fifty unrelated normal Chinese volunteers served as the controls. RESULTS Eighteen different mutations in the CHST6 gene (including 15 novel mutations) were identified, of which 12 were missense mutations, 5 were nonsense mutations, and 1 was a frameshift mutation. Six families had homozygous mutation, and 13 families had compound heterozygous mutation. None of these mutations were detected in the normal controls. CONCLUSIONS CHST6 mutations may be responsible for the pathogenesis of MCD in Chinese patients. The Q298X mutation detected in 5 of 19 families (6 of 38 alleles, 15.8%) may be the founder mutation in Chinese patients. However, our findings also indicate a high level of allelic heterogeneity of the CHST6 gene in Chinese patients and in other ethnic groups.
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Affiliation(s)
- Zuguo Liu
- Eye Institute, The Xiamen University Medical College, Xiamen, Fujian, China
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Weiss JS, Møller HU, Lisch W, Kinoshita S, Aldave AJ, Belin MW, Kivelä T, Busin M, Munier FL, Seitz B, Sutphin J, Bredrup C, Mannis MJ, Rapuano CJ, Van Rij G, Kim EK, Klintworth GK. The IC3D classification of the corneal dystrophies. Cornea 2008; 27 Suppl 2:S1-83. [PMID: 19337156 PMCID: PMC2866169 DOI: 10.1097/ico.0b013e31817780fb] [Citation(s) in RCA: 191] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
BACKGROUND The recent availability of genetic analyses has demonstrated the shortcomings of the current phenotypic method of corneal dystrophy classification. Abnormalities in different genes can cause a single phenotype, whereas different defects in a single gene can cause different phenotypes. Some disorders termed corneal dystrophies do not appear to have a genetic basis. PURPOSE The purpose of this study was to develop a new classification system for corneal dystrophies, integrating up-to-date information on phenotypic description, pathologic examination, and genetic analysis. METHODS The International Committee for Classification of Corneal Dystrophies (IC3D) was created to devise a current and accurate nomenclature. RESULTS This anatomic classification continues to organize dystrophies according to the level chiefly affected. Each dystrophy has a template summarizing genetic, clinical, and pathologic information. A category number from 1 through 4 is assigned, reflecting the level of evidence supporting the existence of a given dystrophy. The most defined dystrophies belong to category 1 (a well-defined corneal dystrophy in which a gene has been mapped and identified and specific mutations are known) and the least defined belong to category 4 (a suspected dystrophy where the clinical and genetic evidence is not yet convincing). The nomenclature may be updated over time as new information regarding the dystrophies becomes available. CONCLUSIONS The IC3D Classification of Corneal Dystrophies is a new classification system that incorporates many aspects of the traditional definitions of corneal dystrophies with new genetic, clinical, and pathologic information. Standardized templates provide key information that includes a level of evidence for there being a corneal dystrophy. The system is user-friendly and upgradeable and can be retrieved on the website www.corneasociety.org/ic3d.
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Affiliation(s)
- Jayne S Weiss
- Department of Ophthalmology, Kresge Eye Institute, Wayne State University School of Medicine, Detroit, MI 48201, USA.
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