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Jeyabalan N, Ghosh A, Mathias GP, Ghosh A. Rare eye diseases in India: A concise review of genes and genetics. Indian J Ophthalmol 2022; 70:2232-2238. [PMID: 35791102 PMCID: PMC9426079 DOI: 10.4103/ijo.ijo_322_22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Rare eye diseases (REDs) are mostly progressive and are the leading cause of irreversible blindness. The disease onset can vary from early childhood to late adulthood. A high rate of consanguinity contributes to India’s predisposition to RED. Most gene variations causing REDs are monogenic and, in some cases, digenic. All three types of Mendelian inheritance have been reported in REDs. Some of the REDs are related to systemic illness with variable phenotypes in affected family members. Approximately, 50% of the children affected by REDs show associated phenotypes at the early stages of the disease. A precise clinical diagnosis becomes challenging due to high clinical and genetic heterogeneity. Technological advances, such as next-generation sequencing (NGS), have improved genetic and genomic testing for REDs, thereby aiding in determining the underlying causative gene variants. It is noteworthy that genetic testing together with genetic counseling facilitates a more personalized approach in the accurate diagnosis and management of the disease. In this review, we discuss REDs identified in the Indian population and their underlying genetic etiology.
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Affiliation(s)
- Nallathambi Jeyabalan
- Molecular Signaling and Gene Therapy Unit, GROW Research Laboratory, Narayana Nethralaya Foundation, Narayana Nethralaya Eye Hospital, Bengaluru, Karnataka, India
| | - Anuprita Ghosh
- Molecular Signaling and Gene Therapy Unit, GROW Research Laboratory, Narayana Nethralaya Foundation, Narayana Nethralaya Eye Hospital, Bengaluru, Karnataka, India
| | - Grace P Mathias
- Molecular Signaling and Gene Therapy Unit, GROW Research Laboratory, Narayana Nethralaya Foundation, Narayana Nethralaya Eye Hospital, Bengaluru, Karnataka, India
| | - Arkasubhra Ghosh
- Molecular Signaling and Gene Therapy Unit, GROW Research Laboratory, Narayana Nethralaya Foundation, Narayana Nethralaya Eye Hospital, Bengaluru, Karnataka, India
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2
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Mizumoto S, Yamada S. Congenital Disorders of Deficiency in Glycosaminoglycan Biosynthesis. Front Genet 2021; 12:717535. [PMID: 34539746 PMCID: PMC8446454 DOI: 10.3389/fgene.2021.717535] [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: 05/31/2021] [Accepted: 08/12/2021] [Indexed: 12/04/2022] Open
Abstract
Glycosaminoglycans (GAGs) including chondroitin sulfate, dermatan sulfate, and heparan sulfate are covalently attached to specific core proteins to form proteoglycans, which are distributed at the cell surface as well as in the extracellular matrix. Proteoglycans and GAGs have been demonstrated to exhibit a variety of physiological functions such as construction of the extracellular matrix, tissue development, and cell signaling through interactions with extracellular matrix components, morphogens, cytokines, and growth factors. Not only connective tissue disorders including skeletal dysplasia, chondrodysplasia, multiple exostoses, and Ehlers-Danlos syndrome, but also heart and kidney defects, immune deficiencies, and neurological abnormalities have been shown to be caused by defects in GAGs as well as core proteins of proteoglycans. These findings indicate that GAGs and proteoglycans are essential for human development in major organs. The glycobiological aspects of congenital disorders caused by defects in GAG-biosynthetic enzymes including specific glysocyltransferases, epimerases, and sulfotransferases, in addition to core proteins of proteoglycans will be comprehensively discussed based on the literature to date.
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Affiliation(s)
- Shuji Mizumoto
- Department of Pathobiochemistry, Faculty of Pharmacy, Meijo University, Nagoya, Japan
| | - Shuhei Yamada
- Department of Pathobiochemistry, Faculty of Pharmacy, Meijo University, Nagoya, Japan
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Singh S, Das S, Kannabiran C, Jakati S, Chaurasia S. Macular Corneal Dystrophy: An Updated Review. Curr Eye Res 2021; 46:765-770. [PMID: 33171054 DOI: 10.1080/02713683.2020.1849727] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Revised: 10/16/2020] [Accepted: 11/01/2020] [Indexed: 01/11/2023]
Abstract
Macular Corneal Dystrophy is an autosomal recessive form of corneal dystrophy due to a mutation in CHST6 gene, which results in abnormal proteoglycan synthesis. There is accumulation of abnormal glycosaminoglycans in the corneal stroma and endothelium. The deposition results in progressive loss of corneal transparency and visual acuity. The histopathology shows characteristic alcian blue positive deposits. Management in the cases with visual loss requires keratoplasty either full thickness or lamellar. The decision about the ideal type of keratoplasty depends on age and pre-operative clinical features. Although prognosis after keratoplasty is good, recurrences can occur. Future research should be targeted towards gene therapy in this condition.
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Affiliation(s)
- Shalini Singh
- Cornea and Anterior Segment Services, LVPEI, Hyderabad, India
| | - Sujata Das
- Cornea and Anterior Segment Services, LVPEI, Bhubneshwar, India
| | - Chitra Kannabiran
- Kallam Anji Reddy Molecular Genetics Laboratory, Prof Brien Holden Eye Research Centre, Hyderabad, India
| | - Saumya Jakati
- Ophthalmic Pathology Laboratory, LVPEI, Hyderabad, India
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Huang Y, Yuan L, Cao Y, Tang R, Xu H, Tang Z, Deng H. Novel compound heterozygous mutations in the CHST6 gene cause macular corneal dystrophy in a Han Chinese family. ANNALS OF TRANSLATIONAL MEDICINE 2021; 9:622. [PMID: 33987320 PMCID: PMC8106006 DOI: 10.21037/atm-20-7178] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
BACKGROUND Macular corneal dystrophy (MCD), a rare autosomal recessive disorder, is caused by pathogenic mutations in the carbohydrate sulfotransferase 6 gene (CHST6) and is characterized by bilateral progressive stromal clouding and vision loss. Corneal transplantation is often necessary. This study aimed to identify disease-causing mutations in a Han-Chinese MCD patient. METHODS A 37-year-old female diagnosed with MCD was recruited. The clinical materials were observed and described, and peripheral blood sample was extracted. Whole exome sequencing (WES) and Sanger sequencing were used to reveal genetic defects. The pathogenicity of identified mutations was assessed using in silico analysis. RESULTS The patient had typical features of MCD, including decreased vision, multiple irregular gray-white corneal opacities, and corneal thinning. A novel nonsense mutation c.544C>T (p.Gln182Ter) and a validated missense mutation c.631C>G (p.Arg211Gly) were identified in the CHST6 gene coding region, both classified as "pathogenic" following the American College of Medical Genetics and Genomics standards and guidelines. CONCLUSIONS This study reports a Han-Chinese MCD patient with a novel nonsense mutation c.544C>T (p.Gln182Ter) and a recurrent missense mutation c.631C>G (p.Arg211Gly), which expand the spectrum of genetic mutations. The results of this study extend genotype-phenotype correlations between the CHST6 gene mutations and MCD clinical findings, contributing to a more accurate diagnosis and the development of potential gene-targeted MCD therapies. KEYWORDS Carbohydrate sulfotransferase 6 gene (CHST6); compound heterozygous mutations; Han Chinese family; macular corneal dystrophy (MCD).
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Affiliation(s)
- Yanxia Huang
- Center for Experimental Medicine, the Third Xiangya Hospital, Central South University, Changsha, China
| | - Lamei Yuan
- Center for Experimental Medicine, the Third Xiangya Hospital, Central South University, Changsha, China
| | - Yanna Cao
- Department of Ophthalmology, the Third Xiangya Hospital, Central South University, Changsha, China
| | - Renhong Tang
- Department of Ophthalmology, the Third Xiangya Hospital, Central South University, Changsha, China
| | - Hongbo Xu
- Center for Experimental Medicine, the Third Xiangya Hospital, Central South University, Changsha, China
| | - Ziqian Tang
- Center for Experimental Medicine, the Third Xiangya Hospital, Central South University, Changsha, China
| | - Hao Deng
- Center for Experimental Medicine, the Third Xiangya Hospital, Central South University, Changsha, China;,Department of Neurology, the Third Xiangya Hospital, Central South University, Changsha, China;,Disease Genome Research Center, Central South University, Changsha, China
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5
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Li W, Qu N, Li JK, Li YX, Han DM, Chen YX, Tian L, Shao K, Yang W, Wang ZS, Chen X, Jin XY, Wang ZW, Liang C, Qian WP, Wang LS, He W. Evaluation of the Genetic Variation Spectrum Related to Corneal Dystrophy in a Large Cohort. Front Cell Dev Biol 2021; 9:632946. [PMID: 33816482 PMCID: PMC8012530 DOI: 10.3389/fcell.2021.632946] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Accepted: 02/02/2021] [Indexed: 11/13/2022] Open
Abstract
AIMS To characterize the genetic landscape and mutation spectrum of patients with corneal dystrophies (CDs) in a large Han ethnic Chinese Cohort with inherited eye diseases (IEDs). METHODS Retrospective study. A large IED cohort was recruited in this study, including 69 clinically diagnosed CD patients, as well as other types of eye diseases patients and healthy family members as controls. The 792 genes on the Target_Eye_792_V2 chip were used to screen all common IEDs in our studies, including 22 CD-related genes. RESULTS We identified 2334 distinct high-quality variants on 22 CD-related genes in a large IEDs cohort. A total of 21 distinct pathogenic or likely pathogenic mutations were identified, and the remaining 2313 variants in our IED cohort had no evidence of CD-related pathogenicity. Overall, 81.16% (n = 56/69) of CD patients received definite molecular diagnoses, and transforming growth factor-beta-induced protein (TGFBI), CHTS6, and SLC4A11 genes covered 91.07, 7.14, and 1.79% of the diagnosed cases, respectively. Twelve distinct disease-associated mutations in the TGFBI gene were identified, 11 of which were previously reported and one is novel. Four of these TGFBI mutations (p.D123H, p.M502V, p.P501T, and p.P501A) were redefined as likely benign in our Han ethnic Chinese IED cohort after performing clinical variant interpretation. These four TGFBI mutations were detected in asymptomatic individuals but not in CD patients, especially the previously reported disease-causing mutation p.P501T. Among 56 CD patients with positive detected mutations, the recurrent TGFBI mutations were p.R124H, p.R555W, p.R124C, p.R555Q, and p.R124L, and the proportions were 32.14, 19.64, 14.29, 10.71, and 3.57%, respectively. Twelve distinct pathogenic or likely pathogenic mutations of CHTS6 were detected in 28 individuals. The recurrent mutations were p.Y358H, p.R140X, and p.R205W, and the proportions were 25.00, 21.43, and 14.29%, respectively. All individuals associated with TGFBI were missense mutations; 74.19% associated with CHTS6 mutations were missense mutations, and 25.81% were non-sense mutations. Hot regions were located in exons 4 and 12 of TGFBI individuals and located in exon 3 of CHTS6 individuals. No de novo mutations were identified. CONCLUSION For the first time, our large cohort study systematically described the variation spectrum of 22 CD-related genes and evaluated the frequency and pathogenicity of all 2334 distinct high-quality variants in our IED cohort. Our research will provide East Asia and other populations with baseline data from a Han ethnic population-specific level.
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Affiliation(s)
- Wei Li
- BGI Education Center, University of Chinese Academy of Sciences, Shenzhen, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
- Shenyang Industrial Technology Institute of Ophthalmology, Shenyang, China
| | - Ning Qu
- Department of Reproductive Medicine, Peking University Shenzhen Hospital, Shenzhen, China
| | - Jian-Kang Li
- City University of Hong Kong Shenzhen Research Institute, Shenzhen, China
| | - Yu-Xin Li
- BGI Education Center, University of Chinese Academy of Sciences, Shenzhen, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
- School of Basic Medicine, Qingdao University, Qingdao, China
| | - Dong-Ming Han
- BGI Education Center, University of Chinese Academy of Sciences, Shenzhen, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Yi-Xi Chen
- School of Biology and Biological Engineering, South China University of Technology, Guangzhou, China
| | - Le Tian
- BGI Education Center, University of Chinese Academy of Sciences, Shenzhen, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
- School of Basic Medicine, Qingdao University, Qingdao, China
| | - Kang Shao
- City University of Hong Kong Shenzhen Research Institute, Shenzhen, China
| | - Wen Yang
- City University of Hong Kong Shenzhen Research Institute, Shenzhen, China
| | - Zhuo-Shi Wang
- Shenyang Industrial Technology Institute of Ophthalmology, Shenyang, China
- He Eye Specialists Hospital, He University, Shenyang, China
| | - Xuan Chen
- College of Plant Protection, Hunan Agricultural University, Changsha, China
| | - Xiao-Ying Jin
- College of Informatics, HuaZhong Agricultural University, Wuhan, China
| | - Zi-Wei Wang
- BGI Education Center, University of Chinese Academy of Sciences, Shenzhen, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Chen Liang
- School of Basic Medicine, Qingdao University, Qingdao, China
| | - Wei-Ping Qian
- Department of Reproductive Medicine, Peking University Shenzhen Hospital, Shenzhen, China
| | - Lu-Sheng Wang
- City University of Hong Kong Shenzhen Research Institute, Shenzhen, China
| | - Wei He
- Shenyang Industrial Technology Institute of Ophthalmology, Shenyang, China
- He Eye Specialists Hospital, He University, Shenyang, China
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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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Puri S, Coulson-Thomas YM, Gesteira TF, Coulson-Thomas VJ. Distribution and Function of Glycosaminoglycans and Proteoglycans in the Development, Homeostasis and Pathology of the Ocular Surface. Front Cell Dev Biol 2020; 8:731. [PMID: 32903857 PMCID: PMC7438910 DOI: 10.3389/fcell.2020.00731] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Accepted: 07/15/2020] [Indexed: 12/20/2022] Open
Abstract
The ocular surface, which forms the interface between the eye and the external environment, includes the cornea, corneoscleral limbus, the conjunctiva and the accessory glands that produce the tear film. Glycosaminoglycans (GAGs) and proteoglycans (PGs) have been shown to play important roles in the development, hemostasis and pathology of the ocular surface. Herein we review the current literature related to the distribution and function of GAGs and PGs within the ocular surface, with focus on the cornea. The unique organization of ECM components within the cornea is essential for the maintenance of corneal transparency and function. Many studies have described the importance of GAGs within the epithelial and stromal compartment, while very few studies have analyzed the ECM of the endothelial layer. Importantly, GAGs have been shown to be essential for maintaining corneal homeostasis, epithelial cell differentiation and wound healing, and, more recently, a role has been suggested for the ECM in regulating limbal stem cells, corneal innervation, corneal inflammation, corneal angiogenesis and lymphangiogenesis. Reports have also associated genetic defects of the ECM to corneal pathologies. Thus, we also highlight the role of different GAGs and PGs in ocular surface homeostasis, as well as in pathology.
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Affiliation(s)
- Sudan Puri
- College of Optometry, University of Houston, Houston, TX, United States
| | - Yvette M Coulson-Thomas
- Molecular Biology Section, Department of Biochemistry, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Tarsis F Gesteira
- College of Optometry, University of Houston, Houston, TX, United States.,Optimvia, LLC, Batavia, OH, United States
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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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Tetas Pont R, Downs L, Pettitt L, Busse C, Mellersh CS. A Carbohydrate Sulfotransferase-6 (CHST6) gene mutation is associated with Macular Corneal Dystrophy in Labrador Retrievers. Vet Ophthalmol 2016; 19:488-492. [PMID: 26585178 DOI: 10.1111/vop.12332] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2023]
Abstract
PURPOSE To locate and identify variants associated with macular corneal dystrophy (MCD) in Labrador Retriever (LR) dogs, in the candidate gene carbohydrate sulfotransferase-6 (CHST6). METHODS The single coding exon of canine CHST6 was sequenced in one affected LR with MCD and one control LR clinically clear of ocular disease. A further 71 control LR with unknown clinical status were sequenced for the putative causal variant in CHST6. A TaqMan SNP genotyping assay was developed and used to screen an additional 84 dogs (five affected LR and 79 clinically clear LR). Finally, the variant was screened in a third cohort of 89 unrelated LR with unknown clinical status to estimate its allele frequency in the population of LR in the United Kingdom. RESULTS A single nucleotide polymorphism (SNP) was identified within the coding exon of CHST6, resulting in a missense mutation (c.814C>A, p.R272S). All six LR affected with MCD were homozygous for the mutant allele, while 140/151 control LR were homozygous for the wild-type allele and 11/151 were heterozygous for the mutation, indicating an association with MCD (P < 10-5 ). The mutant allele was present in the unrelated LR cohort at a frequency of 0.017, suggesting carrier and affection rates of 3.3% and 0.028%, respectively. CONCLUSIONS A missense mutation in the CHST6 gene is strongly associated with autosomal recessive MCD in the LR.
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Affiliation(s)
- Roser Tetas Pont
- Comparative Ophthalmology Unit, Animal Health Trust, Lanwades Park, Kentford, CB8 7UU, UK.
| | - Louise Downs
- Canine Genetics, Animal Health Trust, Lanwades Park, Kentford, CB8 7UU, UK
| | - Louise Pettitt
- Canine Genetics, Animal Health Trust, Lanwades Park, Kentford, CB8 7UU, UK
| | - Claudia Busse
- Comparative Ophthalmology Unit, Animal Health Trust, Lanwades Park, Kentford, CB8 7UU, UK
| | - Cathryn S Mellersh
- Canine Genetics, Animal Health Trust, Lanwades Park, Kentford, CB8 7UU, UK
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Carstens N, Williams S, Goolam S, Carmichael T, Cheung MS, Büchmann-Møller S, Sultan M, Staedtler F, Zou C, Swart P, Rice DS, Lacoste A, Paes K, Ramsay M. Novel mutation in the CHST6 gene causes macular corneal dystrophy in a black South African family. BMC MEDICAL GENETICS 2016; 17:47. [PMID: 27439461 PMCID: PMC4955246 DOI: 10.1186/s12881-016-0308-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/06/2015] [Accepted: 06/23/2016] [Indexed: 12/30/2022]
Abstract
BACKGROUND Macular corneal dystrophy (MCD) is a rare autosomal recessive disorder that is characterized by progressive corneal opacity that starts in early childhood and ultimately progresses to blindness in early adulthood. The aim of this study was to identify the cause of MCD in a black South African family with two affected sisters. METHODS A multigenerational South African Sotho-speaking family with type I MCD was studied using whole exome sequencing. Variant filtering to identify the MCD-causal mutation included the disease inheritance pattern, variant minor allele frequency and potential functional impact. RESULTS Ophthalmologic evaluation of the cases revealed a typical MCD phenotype and none of the other family members were affected. An average of 127 713 variants per individual was identified following exome sequencing and approximately 1.2 % were not present in any of the investigated public databases. Variant filtering identified a homozygous E71Q mutation in CHST6, a known MCD-causing gene encoding corneal N-acetyl glucosamine-6-O-sulfotransferase. This E71Q mutation results in a non-conservative amino acid change in a highly conserved functional domain of the human CHST6 that is essential for enzyme activity. CONCLUSION We identified a novel E71Q mutation in CHST6 as the MCD-causal mutation in a black South African family with type I MCD. This is the first description of MCD in a black Sub-Saharan African family and therefore contributes valuable insights into the genetic aetiology of this disease, while improving genetic counselling for this and potentially other MCD families.
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Affiliation(s)
- Nadia Carstens
- />Sydney Brenner Institute for Molecular Bioscience, University of the Witwatersrand, 2050 Johannesburg, Gauteng South Africa
| | - Susan Williams
- />Division of Ophthalmology, Department of Neurosciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Saadiah Goolam
- />Division of Ophthalmology, Department of Neurosciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Trevor Carmichael
- />Division of Ophthalmology, Department of Neurosciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Ming Sin Cheung
- />Biomarker Development, Novartis Institutes for BioMedical Research, Basel, Switzerland
| | - Stine Büchmann-Møller
- />Biomarker Development, Novartis Institutes for BioMedical Research, Basel, Switzerland
| | - Marc Sultan
- />Biomarker Development, Novartis Institutes for BioMedical Research, Basel, Switzerland
| | - Frank Staedtler
- />Biomarker Development, Novartis Institutes for BioMedical Research, Basel, Switzerland
| | - Chao Zou
- />Center for Proteomic Chemistry, Novartis Institutes for BioMedical Research, Basel, Switzerland
| | - Peter Swart
- />Division of Anatomical Pathology, National Health Laboratory Services and University of the Witwatersrand, Johannesburg, South Africa
| | - Dennis S. Rice
- />Novartis Institutes for Biomedical Research, Cambridge, USA
| | - Arnaud Lacoste
- />Novartis Institutes for Biomedical Research, Cambridge, USA
| | - Kim Paes
- />Novartis Institutes for Biomedical Research, Cambridge, USA
| | - Michèle Ramsay
- />Sydney Brenner Institute for Molecular Bioscience, University of the Witwatersrand, 2050 Johannesburg, Gauteng South Africa
- />Division of Human Genetics, National Health Laboratory Service and Faculty of Health Sciences, University of the Witwatersrand, 2050 Johannesburg, Gauteng South Africa
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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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13
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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: 195] [Impact Index Per Article: 12.2] [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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14
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Yellore VS, Sonmez B, Chen MC, Rayner SA, Thonar EJ, Aldave AJ. An unusual presentation of macular corneal dystrophy associated with uniparental isodisomy and a novel Leu173Pro mutation. Ophthalmic Genet 2007; 28:169-74. [PMID: 17896316 DOI: 10.1080/13816810701407925] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
PURPOSE To report an unusual phenotype of macular corneal dystrophy (MCDC1) associated with a novel CHST6 mutation transmitted via maternal isodisomy. METHODS Slit lamp examination of the patient and his parents was performed. DNA was collected from each individual for amplification and sequencing of the CHST6 coding region, as well as exons 4 and 12 of TGFBI. Serum antigenic keratan sulfate (AgKS) levels were measured for confirmation of the diagnosis and subtyping of MCDC1. Quantitative real-time PCR (qPCR) was performed to differentiate between homozygous and hemizygous sequence variants. Genotyping at 12 single nucleotide polymorphisms (SNPs) within and surrounding CHST6 was performed to determine the pattern of inheritance of mutations identified in CHST6. RESULTS Examination of the proband revealed bilateral, discrete, axially distributed, gray-white deposits at the level of Bowman's layer, with diffuse fine corneal stromal haze. Screening of TGFBI exons 4 and 12 in the proband did not reveal any allelic variants. However, screening of CHST6 in the proband demonstrated a novel homozygous missense mutation involving a highly conserved amino acid (c.518T > C; Leu173Pro) and undetectable serum AgKS levels in the proband confirmed the diagnosis of type I MCDC1. Quantitative PCR confirmed that both copies of CHST6 were present in the patient, excluding the possibility that the mutation was present in the hemizygous state. The results of genotyping were consistent with maternal isodisomy, as the patient was homozygous for an allele possessed by his mother at each SNP, two of which were informative and demonstrated nonpaternal inheritance. CONCLUSION A phenotypically unusual variant of MCDC1 was found to be associated with the novel Leu173Pro mutation in CHST6, transmitted via uniparental isodisomy, a previously unreported pattern of inheritance in the corneal dystrophies.
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Affiliation(s)
- Vivek S Yellore
- Cornea Service, Jules Stein Eye Institute, David Geffen School of Medicine at UCLA, Los Angeles, California 90095, USA
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15
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Young RD, Akama TO, Liskova P, Ebenezer ND, Allan B, Kerr B, Caterson B, Fukuda MN, Quantock AJ. Differential immunogold localisation of sulphated and unsulphated keratan sulphate proteoglycans in normal and macular dystrophy cornea using sulphation motif-specific antibodies. Histochem Cell Biol 2006; 127:115-20. [PMID: 16944190 DOI: 10.1007/s00418-006-0228-8] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/24/2006] [Indexed: 11/26/2022]
Abstract
Keratan sulphate (KS) proteoglycans (PGs) are key molecules in the corneal stroma for tissue organisation and transparency. Macular corneal dystrophy (MCD) is a rare, autosomal recessive disease characterised by disturbances in KS expression. MCD is caused by mutations in CHST6, a gene encoding the enzyme responsible for KS sulphation. Sulphated KS is absent in type I disease causing corneal opacity and loss of vision. Genetic studies have highlighted the mutational heterogeneity in MCD, but supportive immunohistochemical studies on corneal KS have previously been limited by the availability of antibodies mostly reactive only with highly sulphated KS epitopes. In this study, we employed four antibodies against specific KS sulphation patterns, including one against unsulphated KS, to investigate their reactivity in a case of MCD compared with normal cornea using high-resolution immunogold electron microscopy. Mutation analysis indicated type I MCD with deletion of the entire open reading frame of CHST6. Contrast enhanced fixation revealed larger PG structures in MCD than normal. Unlike normal cornea, MCD cornea showed positive labelling with antibody to unsulphated KSPG, but was negative with antibodies to sulphated KSPG. These antibodies will thus facilitate high-resolution investigations of phenotypic heterogeneity in support of genetic studies in this disease.
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Affiliation(s)
- Robert D Young
- Structural Biophysics Group, School of Optometry & Vision Sciences, Cardiff University, Redwood Building, King Edward VII Avenue, Cardiff, CF10 3NB Wales, UK
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