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Lin Q, Zheng L, Shen Z. A novel variant in TGFBI causes keratoconus in a two-generation Chinese family. Ophthalmic Genet 2021; 43:159-163. [PMID: 34895010 DOI: 10.1080/13816810.2021.2015788] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
BACKGROUND This study aims to investigate the genetic abnormalities in a two-generation Chinese family affected by keratoconus (KC). A two-generation Chinese family affected by KC was studied. MATERIALS AND METHODS A total of 118 unrelated healthy individuals without KC were recruited as controls. The family history, clinical data, and peripheral blood leukocytes were collected from all subjects. Whole exome sequencing was performed using the genomic DNA of the proband (II.2) and the other two affected family members (I.1 and II.3). Afterwards, polymerase chain reaction was performed for the other enrolled subjects to verify the variants identified in family members with KC. The PolyPhen2, SIFT, PROVEIN and Mutation Taster software programs were applied to analyze the functional consequences of the variants. RESULTS A single nucleotide polymorphism (VARIANT) (c.1406 G > A [rs759370852]) in the transforming growth factor beta-induced (TGFBI) gene was identified in all affected family members, which resulted in a p.R469H amino acid change. This variant was not detected in the controls. The variant c.1406 G > A in TGFBI was predicted as probably damaging with software programs. CONCLUSION A novel variant c.1406 G > A in TGFBI has been identified, and probably contributes to the pathogenesis of KC.
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Affiliation(s)
- Qinghong Lin
- Refractive Surgery Department, Hefei Bright Eye Hospital, Hefei, Anhui Province, China
| | - Lin Zheng
- Refractive Surgery Department, Hefei Bright Eye Hospital, Hefei, Anhui Province, China
| | - Zhengwei Shen
- Refractive Surgery Department, Hefei Bright Eye Hospital, Hefei, Anhui Province, China
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Ates KM, Estes AJ, Liu Y. Potential underlying genetic associations between keratoconus and diabetes mellitus. ADVANCES IN OPHTHALMOLOGY PRACTICE AND RESEARCH 2021; 1:100005. [PMID: 34746916 PMCID: PMC8570550 DOI: 10.1016/j.aopr.2021.100005] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Revised: 08/18/2021] [Accepted: 08/29/2021] [Indexed: 12/14/2022]
Abstract
Background Keratoconus (KC) is the most common ectatic corneal disease, characterized by significantly localized thinning of the corneal stroma. Genetic, environmental, hormonal, and metabolic factors contribute to the pathogenesis of KC. Additionally, multiple comorbidities, such as diabetes mellitus, may affect the risk of KC. Main Body Patients with diabetes mellitus (DM) have been reported to have lower risk of developing KC by way of increased endogenous collagen crosslinking in response to chronic hyperglycemia. However, this remains a debated topic as other studies have suggested either a positive association or no association between DM and KC. To gain further insight into the underlying genetic components of these two diseases, we reviewed candidate genes associated with KC and central corneal thickness in the literature. We then explored how these genes may be regulated similarly or differentially under hyperglycemic conditions and the role they play in the systemic complications associated with DM. Conclusion Our comprehensive review of potential genetic factors underlying KC and DM provides a direction for future studies to further determine the genetic etiology of KC and how it is influenced by systemic diseases such as diabetes.
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Affiliation(s)
- Kristin M. Ates
- Department of Cellular Biology and Anatomy, Medical College of Georgia, Augusta University, Augusta, GA, USA
- Department of Ophthalmology, Medical College of Georgia, Augusta University, Augusta, GA, USA
| | - Amy J. Estes
- Department of Ophthalmology, Medical College of Georgia, Augusta University, Augusta, GA, USA
- James and Jean Culver Vision Discovery Institute, Medical College of Georgia, Augusta University, Augusta, GA, USA
| | - Yutao Liu
- Department of Cellular Biology and Anatomy, Medical College of Georgia, Augusta University, Augusta, GA, USA
- James and Jean Culver Vision Discovery Institute, Medical College of Georgia, Augusta University, Augusta, GA, USA
- Center for Biotechnology and Genomic Medicine, Medical College of Georgia, Augusta University, Augusta, GA, USA
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Kuot A, Hewitt AW, Snibson GR, Souzeau E, Mills R, Craig JE, Burdon KP, Sharma S. TGC repeat expansion in the TCF4 gene increases the risk of Fuchs' endothelial corneal dystrophy in Australian cases. PLoS One 2017; 12:e0183719. [PMID: 28832669 PMCID: PMC5568371 DOI: 10.1371/journal.pone.0183719] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Accepted: 08/09/2017] [Indexed: 11/18/2022] Open
Abstract
Fuchs' endothelial corneal dystrophy (FECD) is a progressive, vision impairing disease. Common single nucleotide polymorphisms (SNPs) and a trinucleotide repeat polymorphism, thymine-guanine-cytosine (TGC), in the TCF4 gene have been associated with the risk of FECD in some populations. We previously reported association of SNPs in TCF4 with FECD risk in the Australian population. The aim of this study was to determine whether TGC repeat polymorphism in TCF4 is associated with FECD in the Australian population. In 189 unrelated Australian cases with advanced late-onset FECD and 183 matched controls, the TGC repeat polymorphism located in intron 3 of TCF4 was genotyped using a short tandem repeat (STR) assay. The repeat length was verified by direct sequencing in selected homozygous carriers. We found significant association between the expanded TGC repeat (≥ 40 repeats) in TCF4 and advanced FECD (P = 2.58 × 10-22; OR = 15.66 (95% CI: 7.79-31.49)). Genotypic analysis showed that 51% of cases (97) compared to 5% of controls (9) were heterozygous or homozygous for the expanded repeat allele. Furthermore, the repeat expansion showed stronger association than the most significantly associated SNP, rs613872, in TCF4, with the disease in the Australian cohort. This and haplotype analysis of both the polymorphisms suggest that considering both the polymorphisms together rather than either of the two alone would better predict susceptibility to FECD in the Australian population. This is the first study to report association of the TGC trinucleotide repeat expansion in TCF4 with advanced FECD in the Australian population.
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Affiliation(s)
- Abraham Kuot
- Department of Ophthalmology, College of Medicine and Public Health, Flinders University, Adelaide, South Australia, Australia
| | - Alex W. Hewitt
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, Melbourne, Victoria, Australia
- Menzies Institute for Medical Research, University of Tasmania, Tasmania, Australia
| | - Grant R. Snibson
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, Melbourne, Victoria, Australia
| | - Emmanuelle Souzeau
- Department of Ophthalmology, College of Medicine and Public Health, Flinders University, Adelaide, South Australia, Australia
| | - Richard Mills
- Department of Ophthalmology, College of Medicine and Public Health, Flinders University, Adelaide, South Australia, Australia
| | - Jamie E. Craig
- Department of Ophthalmology, College of Medicine and Public Health, Flinders University, Adelaide, South Australia, Australia
| | - Kathryn P. Burdon
- Department of Ophthalmology, College of Medicine and Public Health, Flinders University, Adelaide, South Australia, Australia
- Menzies Institute for Medical Research, University of Tasmania, Tasmania, Australia
| | - Shiwani Sharma
- Department of Ophthalmology, College of Medicine and Public Health, Flinders University, Adelaide, South Australia, Australia
- * E-mail:
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Bykhovskaya Y, Margines B, Rabinowitz YS. Genetics in Keratoconus: where are we? EYE AND VISION 2016; 3:16. [PMID: 27350955 PMCID: PMC4922054 DOI: 10.1186/s40662-016-0047-5] [Citation(s) in RCA: 66] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/17/2016] [Accepted: 06/03/2016] [Indexed: 01/06/2023]
Abstract
Keratoconus (KC) is a non-inflammatory thinning and protrusion of the cornea in which the cornea assumes a conical shape. Complex etiology of this condition at present remains an enigma. Although environmental factors have been involved in KC pathogenesis, strong underlining genetic susceptibility has been proven. The lack of consistent findings among early genetic studies suggested a heterogeneity and complex nature of the genetic contribution to the development of KC. Recently, genome-wide linkage studies (GWLS) and genome-wide association studies (GWAS) were undertaken. Next-generation sequencing (NGS)-based genomic screens are also currently being carried out. Application of these recently developed comprehensive genetic tools led to a much greater success and increased reproducibility of genetic findings in KC. Involvement of the LOX gene identified through GWLS has been confirmed in multiple cohorts of KC patients around the world. KC susceptibility region located at the 2q21.3 chromosomal region near the RAB3GAP1 gene identified through GWAS was independently replicated. Rare variants in the ZNF469 gene (mutated in corneal dystrophy Brittle Cornea Syndrome) and in the TGFBI gene (mutated in multiple corneal epithelial–stromal TGFBI dystrophies) have been repeatedly identified in familial and sporadic KC patients of different ethnicities. Additional comprehensive strategies using quantitative endophenotypes have been successfully employed to bring further understanding to the genetics of KC. Additional genetic determinants including the COL5A1 gene have been identified in the GWAS of KC-related trait central corneal thickness. These recent discoveries confirmed the importance of the endophenotype approach for studying complex genetic diseases such as KC and showed that different connective tissue disorders may have the same genetic determinants.
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Affiliation(s)
- Yelena Bykhovskaya
- Regenerative Medicine Institute and Department of Surgery, Cedars-Sinai Medical Center, Los Angeles, USA ; Cornea Genetic Eye Institute, 50 N. La Cienega Blvd. Suite #340, Beverly Hills, CA 90211 USA
| | - Benjamin Margines
- Cornea Genetic Eye Institute, 50 N. La Cienega Blvd. Suite #340, Beverly Hills, CA 90211 USA
| | - Yaron S Rabinowitz
- Regenerative Medicine Institute and Department of Surgery, Cedars-Sinai Medical Center, Los Angeles, USA ; Cornea Genetic Eye Institute, 50 N. La Cienega Blvd. Suite #340, Beverly Hills, CA 90211 USA ; The Jules Stein Eye Institute, University of California Los Angeles, Los Angeles, USA
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Bykhovskaya Y, Gromova A, Makarenkova HP, Rabinowitz YS. Abnormal regulation of extracellular matrix and adhesion molecules in corneas of patients with keratoconus. ACTA ACUST UNITED AC 2016; 5:63-70. [PMID: 28989906 DOI: 10.5005/jp-journals-10025-1123] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
AIM To identify changes in the expression of genes coding for extracellular matrix (ECM) proteins in patients with non-inflammatory corneal disorder keratoconus (KC), patients with corneal scarring, and normal controls. MATERIALS AND METHODS Total RNA extracted from corneal tissue of 13 KC patients, 2 patients with corneal scaring and 4 normal controls was analyzed using Human Extracellular Matrix & Adhesion Molecules Profiler PCR Array. Statistically significant changes in gene expression were identified using the Data Analysis software. RESULTS Comparison of KC and control corneas with thresholds of 1.5 or greater fold change and a p-value of 0.05 or lower, revealed 21 differentially expressed genes, 16 genes were downregulated and 5 were upregulated. Among transcripts downregulated in KC patients we identified THBS1, ADAMTS1, SPP1, several collagens and integrins. We found TGFBI (BIGH3) gene was the most significantly upregulated transcript. CONCLUSION Development of keratoconus results in deregulation of gene expression of extracellular matrix and adhesion molecules. CLINICAL SIGNIFICANCE Downregulation of collagens and upregulation of TGFBI repeatedly identified in KC patients may be used as clinical markers of the disease.
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Affiliation(s)
- Yelena Bykhovskaya
- Regenerative Medicine Institute and Department of Surgery, Cedars-Sinai, USA.,Cornea Genetic Eye Institute, USA
| | - Anastasia Gromova
- Department of Cell and Molecular Biology, The Scripps Research Institute, USA
| | - Helen P Makarenkova
- Department of Cell and Molecular Biology, The Scripps Research Institute, USA
| | - Yaron S Rabinowitz
- Regenerative Medicine Institute and Department of Surgery, Cedars-Sinai, USA.,Cornea Genetic Eye Institute, USA.,The Jules Stein Eye Institute, University of California Los Angeles, USA
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Chen Y, Huang K, Nakatsu MN, Xue Z, Deng SX, Fan G. Identification of novel molecular markers through transcriptomic analysis in human fetal and adult corneal endothelial cells. Hum Mol Genet 2012; 22:1271-9. [PMID: 23257286 DOI: 10.1093/hmg/dds527] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The corneal endothelium is composed of a monolayer of corneal endothelial cells (CECs), which is essential for maintaining corneal transparency. To better characterize CECs in different developmental stages, we profiled mRNA transcriptomes in human fetal and adult corneal endothelium with the goal to identify novel molecular markers in these cells. By comparing CECs with 12 other tissue types, we identified 245 and 284 signature genes that are highly expressed in fetal and adult CECs, respectively. Functionally, these genes are enriched in pathways characteristic of CECs, including inorganic anion transmembrane transporter, extracellular matrix structural constituent and cyclin-dependent protein kinase inhibitor activity. Importantly, several of these genes are disease target genes in hereditary corneal dystrophies, consistent with their functional significance in CEC physiology. We also identified stage-specific markers associated with CEC development, such as specific members in the transforming growth factor beta and Wnt signaling pathways only expressed in fetal, but not in adult CECs. Lastly, by the immunohistochemistry of ocular tissues, we demonstrated the unique protein localization for Wnt5a, S100A4, S100A6 and IER3, the four novel markers for fetal and adult CECs. The identification of a new panel of stage-specific markers for CECs would be very useful for characterizing CECs derived from stem cells or ex vivo expansion for cell replacement therapy.
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Affiliation(s)
- Yinyin Chen
- Translational Center for Stem Cell Research, Tongji Hospital, Department of Regenerative Medicine, Tongji University School of Medicine, Shanghai, China
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Association of TCF4 and CLU polymorphisms with Fuchs' endothelial dystrophy and implication of CLU and TGFBI proteins in the disease process. Eur J Hum Genet 2012; 20:632-8. [PMID: 22234156 DOI: 10.1038/ejhg.2011.248] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Fuchs' endothelial dystrophy (FED) is a disease affecting the corneal endothelium. Recent studies reported significant association of polymorphisms in the TCF4 (transcription factor 4) gene, and a borderline association of PTPRG (protein tyrosine phosphatase, receptor type, G) variants with late-onset FED in Caucasians from the United States. Association of TCF4 has also been reported in the Chinese population. We aimed to determine association of the reported polymorphisms in TCF4 and PTPRG, and association of polymorphisms in the candidate genes ZEB1 (zinc-finger E-box binding homoebox 1), COL8A2 (collagen, type VIII, alpha 2), TGFBI (transforming growth factor, β-induced) and CLU (clusterin) in Australian cases. We also compared the expression of TGFBI and CLU proteins between FED and normal whole corneas. In all, 30 single-nucleotide polymorphisms (SNPs) from the candidate genes were genotyped in 103 cases and 275 controls. Each SNP and haplotype was assessed for association with the disease. SNP analysis identified an association of TCF4 (rs613872 (P=5.25 × 10(-15), OR=4.05), rs9954153 (P=3.37 × 10(-7), OR=2.58), rs2286812 (P=4.23 × 10(-6), OR=2.55) and rs17595731 (P=3.57 × 10(-5), OR=3.79)), CLU (rs17466684; P=0.003, OR=1.85) and one haplotype of TGFBI SNPs (P=0.011, OR=2.29) with FED in Caucasian Australians. No evidence for genetic association of PTPRG, ZEB1 and COL8A2 was found. Immunohistochemistry showed differential expression of CLU and TGFBI proteins in FED-affected compared with normal corneas. In conclusion, variation in TCF4, CLU and TGFBI, but not PTPRG, ZEB1 and COL8A2 genes are associated with FED in Caucasian Australian cases. Differential expression of CLU and TGFBI proteins in FED-affected corneas provides novel insights into the disease mechanism.
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Vilas GL, Loganathan SK, Quon A, Sundaresan P, Vithana EN, Casey J. Oligomerization of SLC4A11 protein and the severity of FECD and CHED2 corneal dystrophies caused by SLC4A11 mutations. Hum Mutat 2011; 33:419-28. [PMID: 22072594 DOI: 10.1002/humu.21655] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2011] [Accepted: 10/31/2011] [Indexed: 11/06/2022]
Abstract
Mutations in the SLC4A11 gene, which encodes a plasma membrane borate transporter, cause recessive congenital hereditary endothelial corneal dystrophy type 2 (CHED2), corneal dystrophy and perceptive deafness (Harboyan syndrome), and dominant late-onset Fuchs endothelial corneal dystrophy (FECD). We analyzed missense SLC4A11 mutations identified in FECD and CHED2 patients and expressed in transfected HEK 293 cells. Chemical cross-linking and migration in nondenaturing gels showed that SLC4A11 exists as a dimer. Furthermore, co-immunoprecipitation of epitope-tagged proteins revealed heteromeric interactions between wild-type (WT) and mutant SLC4A11 proteins. When expressed alone, FECD- and CHED2-causing mutant SLC4A11 proteins are primarily retained intracellularly. Co-expression with WT SLC4A11 partially rescued the cell surface trafficking of CHED2 mutants, but not FECD mutants. CHED2 alleles of SLC4A11 did not affect cell surface processing of WT SLC4A11. In contrast, FECD mutants reduced WT cell surface processing efficiency, consistent with dominant inheritance of FECD. The reduction in movement of WT protein to the cell surface caused by FECD SLC4A11 helps to explain the dominant inheritance of this disorder. Similarly, the failure of CHED2 mutant SLC4A11 to affect the processing of WT protein, explains the lack of symptoms found in CHED2 carriers and the recessive inheritance of the disorder.
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Affiliation(s)
- Gonzalo L Vilas
- Membrane Protein Disease Research Group, Department of Physiology, School of Molecular and Systems Medicine, University of Alberta, Edmonton, Canada
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