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Yaqoob Shahani M, Memon S, Ahmed Sheikh S, Bano U, Shaikh P, Gul Memon S, Begum Shahani S, din Ujjan I, Kumar Narsani A, Muhammad Waryah A. GENETIC HETEROGENEITY OF PRIMARY OPEN-ANGLE GLAUCOMA IN PAKISTAN. Saudi J Biol Sci 2022; 30:103488. [DOI: 10.1016/j.sjbs.2022.103488] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Revised: 09/25/2022] [Accepted: 10/25/2022] [Indexed: 11/06/2022] Open
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Selvan H, Gupta S, Wiggs JL, Gupta V. Juvenile-onset open-angle glaucoma - A clinical and genetic update. Surv Ophthalmol 2022; 67:1099-1117. [PMID: 34536459 PMCID: PMC9192165 DOI: 10.1016/j.survophthal.2021.09.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Revised: 09/06/2021] [Accepted: 09/13/2021] [Indexed: 01/03/2023]
Abstract
Juvenile-onset open-angle glaucoma (JOAG) is a subset of primary open-angle glaucoma that is diagnosed before 40 years of age. The disease may be familial or non-familial, with proportions varying among different populations. Myocilin mutations are the most commonly associated. JOAG is characterized by high intraocular pressures (IOP), with many patients needing surgery. The mean age at diagnosis is in the 3rd decade, with a male preponderance. Myopia is a common association. The pathophysiology underlying the disease is immaturity of the conventional outflow pathways, which may or may not be observed on gonioscopy and anterior segment optical coherence tomography. The unique optic nerve head features include large discs with deep, steep cupping associated with high IOP-induced damage. Progression rates among JOAG patients are comparable to adult primary glaucomas, but as the disease affects younger patients, the projected disability from this disease is higher. Early diagnosis, prompt management, and life-long monitoring play an important role in preventing disease progression. Gene-based therapies currently under investigation offer future hope.
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Affiliation(s)
- Harathy Selvan
- Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India
| | - Shikha Gupta
- Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India
| | - Janey L. Wiggs
- Ocular Genomics Institute, Massachusetts Eye and Ear, Boston, MA, USA,Department of Ophthalmology, Harvard Medical School, MA, USA
| | - Viney Gupta
- Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India,Corresponding author: Viney Gupta, MD, Dr Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, 110029 India. (V. Gupta)
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Gupta V, Somarajan BI, Gupta S, Walia GK, Singh A, Sofi R, Chaudhary RS, Sharma A. The mutational spectrum of Myocilin gene among familial versus sporadic cases of Juvenile onset open angle glaucoma. Eye (Lond) 2020; 35:400-408. [PMID: 32300215 DOI: 10.1038/s41433-020-0850-z] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Revised: 03/04/2020] [Accepted: 03/06/2020] [Indexed: 01/08/2023] Open
Abstract
PURPOSE Juvenile onset primary open angle glaucoma (JOAG) is a rare disorder associated with high IOP and progressive optic neuropathy in patients diagnosed before the age of 40 years. While in some populations it has primarily an autosomal dominant pattern of inheritance, in others it occurs in a primarily sporadic form. The main aim of the study was to assess the relative prevalence of Myocilin (MYOC) mutations in familial versus sporadic cases of JOAG. METHODS We screened 92 unrelated (sporadic) JOAG patients, and 22 affected families (70 affected members and 36 unaffected) for variations in the MYOC gene. We also analyzed the clinical features associated with these variations. RESULTS Three coding sequence variants were identified as mutations causing JOAG. Four families segregated distinct mutations at Gly367Arg, and two families at Gln337Arg, while only two sporadic JOAG cases harbored MYOC mutations (Gly367Arg and Gln48His). The frequency of MYOC mutations in familial cases (27%) was significantly higher than in sporadic JOAG cases (2%); p = 0.001. A 90% penetrance for the Gly367Arg variant was seen by the age of 40 years in our patients. Characteristic allele signatures, indicative of specific founder effects, were not observed for the Gly367Arg mutation that was looked for in 12 patients among 2 geographically close families, which harbored this mutation. CONCLUSION Our data demonstrated that genetic screening for MYOC mutations should be focused toward cases with familial rather than sporadically occurring JOAG.
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Affiliation(s)
- Viney Gupta
- Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India.
| | - Bindu I Somarajan
- Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India
| | - Shikha Gupta
- Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India
| | | | - Abhishek Singh
- Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India
| | - Rayees Sofi
- Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India
| | - Richard Sher Chaudhary
- Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India
| | - Arundhati Sharma
- Department of Anatomy, All India Institute of Medical Sciences, New Delhi, India
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Multiomic Signature of Glaucoma Predisposition in Flammer Syndrome Affected Individuals – Innovative Predictive, Preventive and Personalised Strategies in Disease Management. FLAMMER SYNDROME 2019. [DOI: 10.1007/978-3-030-13550-8_5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Gupta V, Somarajan BI, Gupta S, Chaurasia AK, Kumar S, Dutta P, Gupta V, Sharma A, Tayo BO, Nischal K. The inheritance of juvenile onset primary open angle glaucoma. Clin Genet 2017; 92:134-142. [PMID: 27779752 DOI: 10.1111/cge.12906] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2016] [Revised: 10/20/2016] [Accepted: 10/21/2016] [Indexed: 12/20/2022]
Abstract
Juvenile onset open angle glaucoma (JOAG) affects patients before 40 years of age, who present with high intraocular pressure and deep steep cupping of the optic nerve head. While it was considered to be inherited in an autosomal dominant fashion, recent studies have shown an autosomal recessive pattern as well as sporadic occurrence of the disease in several families. In this review, we analyze the genetic basis of the disease along with common mutations and their association with JOAG. We also analyzed the inheritance patterns in a large group of unrelated JOAG patients (n = 336) from Northern India wherein the prevalence of familial occurrence was assessed and segregation analysis performed, to determine the mode of inheritance.
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Affiliation(s)
- V Gupta
- Dr Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India
| | - B I Somarajan
- Dr Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India
| | - S Gupta
- Dr Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India
| | - A K Chaurasia
- Dr Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India
| | - S Kumar
- Dr Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India
| | - P Dutta
- Dr Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India
| | - V Gupta
- Department of Anthropology, University of Delhi, New Delhi, India
| | - A Sharma
- Department of Anatomy, All India Institute of Medical Sciences, New Delhi, India
| | - B O Tayo
- Department of Public Health Sciences, Stritch School of Medicine Loyola University Chicago, Maywood, IL, USA
| | - K Nischal
- Department of Pediatric Ophthalmology, Children's Hospital of Pittsburgh of UPMC, Pittsburgh, PA, USA
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Genetic variants associated with primary open angle glaucoma in Indian population. Genomics 2017; 109:27-35. [PMID: 27851990 DOI: 10.1016/j.ygeno.2016.11.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2016] [Revised: 11/07/2016] [Accepted: 11/09/2016] [Indexed: 01/26/2023]
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Kwun Y, Lee EJ, Han JC, Kee C. Clinical Characteristics of Juvenile-onset Open Angle Glaucoma. KOREAN JOURNAL OF OPHTHALMOLOGY 2016; 30:127-33. [PMID: 27051261 PMCID: PMC4820523 DOI: 10.3341/kjo.2016.30.2.127] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2014] [Accepted: 07/15/2015] [Indexed: 12/18/2022] Open
Abstract
PURPOSE To demonstrate the clinical characteristics of juvenile-onset open angle glaucoma (JOAG) and to evaluate the prognostic factors for visual field (VF) progression in eyes with JOAG. METHODS The medical records of 125 eyes of 72 patients with JOAG were analyzed retrospectively. At least four reliable VF tests were required to determine the VF progression, and the progression was defined using the modified Anderson criteria. Comparisons in clinical manifestations among groups were performed using independent t-test, and generalized estimating equations were also conducted. RESULTS The mean follow-up duration was 94.4 ± 50.5 months. Patients with JOAG showed a male preponderance (64 %), myopia (-4.99 ± 4.01 diopters) and a severe elevation of intraocular pressure (35.6 ± 10.8 mmHg). Forty-two JOAG patients (58 %) had complained of symptoms associated with vision and pain; however, one-third presented with no definite symptoms. Fifty-seven patients were diagnosed with JOAG in both eyes, and they were significantly older (p = 0.039) and had a greater family history (p = 0.035) than patients with unilateral JOAG. The progression group exhibited a significantly higher intraocular pressure at the last visit (p = 0.023) than the non-progression group. CONCLUSIONS Because patients with considerable JOAG had no definite symptoms, periodic eye examinations are needed. To prevent the VF's progression, JOAG patients may require more careful management of intraocular pressure.
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Affiliation(s)
- Youngkyo Kwun
- Department of Ophthalmology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Eun Jung Lee
- Department of Ophthalmology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Jong Chul Han
- Department of Ophthalmology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Changwon Kee
- Department of Ophthalmology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
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HUANG XIAOBO, XIAO XUESHAN, JIA XIAOYUN, LI SHIQIANG, LI MIAOLING, GUO XIANGMING, LIU XING, ZHANG QINGJIONG. Mutation analysis of the genes associated with anterior segment dysgenesis, microcornea and microphthalmia in 257 patients with glaucoma. Int J Mol Med 2015; 36:1111-7. [DOI: 10.3892/ijmm.2015.2325] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2014] [Accepted: 08/07/2015] [Indexed: 11/06/2022] Open
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Philomenadin FS, Asokan R, N V, George R, Lingam V, Sarangapani S. Genetic association of SNPs near ATOH7, CARD10, CDKN2B, CDC7 and SIX1/SIX6 with the endophenotypes of primary open angle glaucoma in Indian population. PLoS One 2015; 10:e0119703. [PMID: 25798827 PMCID: PMC4370747 DOI: 10.1371/journal.pone.0119703] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2014] [Accepted: 01/15/2015] [Indexed: 11/18/2022] Open
Abstract
Primary open angle glaucoma (POAG) belonging to a group of optic neuropathies, result from interaction between genetic and environmental factors. Study of associations with quantitative traits (QTs) is one of the successful strategies to understand the complex genetics of POAG. The current study attempts to explore the association of variations near/in genes like ATOH7, SIX1/SIX6 complex, CDKN2B, CARD10, and CDC7 with POAG and its QTs including vertical cup to disc ratio (VCDR), central corneal thickness (CCT), intra ocular pressure (IOP), and axial length (AL). Case-control study design was carried out in a sample size of 97 POAG cases and 371 controls from South India. Model-based (additive, recessive, dominant) association of the genotypes and their interaction was carried out between cases and controls using chi-square, linear and logistic regression methods. Nominal significance (P<0.05) was observed for QTs like i) VCDR with SNPs rs1900004 (ATOH7); rs1192415 (CDC7); rs10483727 (SIX1/SIX6), rs9607469 (CARD10); ii) CCT with rs1192415; iii) IOP with rs1900004 and iv) AL with rs1900004 and rs1063192 (CDKN2B). We were able to replicate previously known interactions between ATOH7-SIX6 and SIX6-CDKN2B along with few novel interactions between ATOH7—CDC7 and SIX6 with genes including CARD10 and CDC7. In summary, our results suggest that a probable interaction among the candidate genes for QTs, play a major role in determining the individual’s susceptibility to POAG.
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Affiliation(s)
- Ferdinamarie Sharmila Philomenadin
- SNONGC Department of Genetics and Molecular biology, Vision Research foundation, Sankara Nethralaya, Chennai, India
- PhD Scholar, Birla Institute of Technology & Science (BITS), Pilani, 333 031, Rajasthan, India
| | - Rashima Asokan
- Chennai Glaucoma Study, Medical and Vision Research Foundation, Sankara Nethralaya, Chennai, India
| | - Viswanathan N
- Biostatistician, Department of Preventive Ophthalmology, Medical research foundation, Sankara Nethralaya, Chennai, India
| | - Ronnie George
- Chennai Glaucoma Study, Medical and Vision Research Foundation, Sankara Nethralaya, Chennai, India
| | - Vijaya Lingam
- Chennai Glaucoma Study, Medical and Vision Research Foundation, Sankara Nethralaya, Chennai, India
| | - Sripriya Sarangapani
- SNONGC Department of Genetics and Molecular biology, Vision Research foundation, Sankara Nethralaya, Chennai, India
- * E-mail:
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Abstract
Normal tension glaucoma (NTG) is a progressive optic neuropathy that mimics primary open-angle glaucoma, but lacks the findings of elevated intraocular pressure or other mitigating factors that can lead to optic neuropathy. The present review summarized the causes, genetics, and mechanisms underlying NTG in both animal models and human patients. We also proposed that the neurovascular unit is a therapeutic target for NTG management.
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Affiliation(s)
- Xue-Song Mi
- Department of Ophthalmology, The First Affiliated Hospital of Jinan University, Guangzhou, People's Republic of China ; Department of Anatomy, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, People's Republic of China
| | - Ti-Fei Yuan
- School of Psychology, Nanjing Normal University, Nanjing, People's Republic of China ; Department of Ophthalmology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, People's Republic of China
| | - Kwok-Fai So
- Department of Anatomy, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, People's Republic of China ; Department of Ophthalmology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, People's Republic of China ; GHM Institute of CNS Regeneration, Jinan University, Guangzhou, People's Republic of China
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Glaucomatous Optic Neuropathy: Risk Assessment and Potential Targets for Effective Prevention and Treatments Tailored to the Patient. ACTA ACUST UNITED AC 2012. [DOI: 10.1007/978-94-007-5866-7_9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/04/2023]
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Golubnitschaja O, Yeghiazaryan K, Flammer J. Key molecular pathways affected by glaucoma pathology: is predictive diagnosis possible? EPMA J 2010; 1:237-44. [PMID: 23199062 PMCID: PMC3405318 DOI: 10.1007/s13167-010-0031-4] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2010] [Accepted: 05/31/2010] [Indexed: 12/22/2022]
Abstract
Prediction and prevention of glaucoma. Neurodegenerative eye disease glaucoma is the second leading cause of blindness with estimated 67 million patients worldwide. Molecular pathomechanisms of glaucoma demonstrate both a considerable overlap with and remarkable particularities compared to other neurodegenerative disorders e.g. Alzheimer's disease. Identification of pathology-specific biomarker-sets is essential to develop advanced diagnostic approaches and personalised patients' treatment. Subcellular imaging and expression patterns in blood as the reliable platform for early/predictive glaucoma diagnosis. Following key pathways are affected in glaucoma pathology: stress response, apoptosis and DNA-repair, adhesion, blood-brain-barrier-breakdown, tissue remodelling, transcription regulation, multidrug resistance and energy metabolism.
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Affiliation(s)
- Olga Golubnitschaja
- Department of Radiology, Rheinische Friedrich-Wilhelms-University of Bonn, Sigmund-Freud-Str. 25, D-53105 Bonn, Germany
- European Association for Predictive, Preventive & Personalised Medicine, www.epmanet.eu
| | - Kristina Yeghiazaryan
- Department of Radiology, Rheinische Friedrich-Wilhelms-University of Bonn, Sigmund-Freud-Str. 25, D-53105 Bonn, Germany
- European Association for Predictive, Preventive & Personalised Medicine, www.epmanet.eu
| | - Josef Flammer
- European Association for Predictive, Preventive & Personalised Medicine, www.epmanet.eu
- Department of Ophthalmology, University of Basel, Basel, Switzerland
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Rautenstrauss B, Mardin C. Targeting glaucoma beyond intraocular pressure. EXPERT REVIEW OF OPHTHALMOLOGY 2010. [DOI: 10.1586/eop.10.21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Ennis S, Gibson J, Griffiths H, Bunyan D, Cree AJ, Robinson D, Self J, MacLeod A, Lotery A. Prevalence of myocilin gene mutations in a novel UK cohort of POAG patients. Eye (Lond) 2009; 24:328-33. [DOI: 10.1038/eye.2009.73] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
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Resch ZT, Fautsch MP. Glaucoma-associated myocilin: a better understanding but much more to learn. Exp Eye Res 2009; 88:704-12. [PMID: 18804106 PMCID: PMC2682697 DOI: 10.1016/j.exer.2008.08.011] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2008] [Revised: 08/18/2008] [Accepted: 08/19/2008] [Indexed: 01/20/2023]
Abstract
Over a decade has passed since myocilin was identified as the first gene linked to early and late-onset primary open-angle glaucoma. During this time, considerable effort has been put forth to understand the functional role myocilin has in normal and glaucomatous eyes. Myocilin is expressed in many ocular and non-ocular tissues, is found in both intracellular and extracellular spaces, and has been linked to elevations in intraocular pressure. Mutations in the myocilin gene that have been associated with glaucoma appear to confer a gain-of-functional activity rather than loss of function. Unfortunately, what the normal function of myocilin is and how alterations in the function can confer a glaucoma phenotype have yet to be elucidated. We will review the current understanding of myocilin with special emphasis on the structural makeup of the myocilin gene and protein, its possible physiological roles internal and external to ocular cells, the regulation of intraocular pressure as evidenced through the use of perfusion culture systems and animal models, and as a causative agent in some forms of glaucoma.
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Affiliation(s)
- Zachary T Resch
- Department of Ophthalmology, Mayo Clinic, Rochester, MN 55905, USA.
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Allingham RR, Liu Y, Rhee DJ. The genetics of primary open-angle glaucoma: a review. Exp Eye Res 2008; 88:837-44. [PMID: 19061886 DOI: 10.1016/j.exer.2008.11.003] [Citation(s) in RCA: 128] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2008] [Revised: 09/26/2008] [Accepted: 11/04/2008] [Indexed: 12/24/2022]
Abstract
Glaucoma is the major cause of irreversible blindness worldwide. Primary open-angle glaucoma (POAG), as the most prevalent form of glaucoma, is a complex inherited disorder and affects more than 2 million individuals in the United States. It has become increasingly clear that a host of genetic as well as environmental factors are likely to contribute to the phenotype. A number of chromosomal and genetic associations have been reported for POAG. This review examines what is currently known about the underlying genetic structure, what remains to be learned, and how this may affect our medical management of this major blinding disease.
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Affiliation(s)
- R Rand Allingham
- Duke University Eye Center, Duke University, Durham, NC 27710, USA.
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Gobeil S, Letartre L, Raymond V. Functional analysis of the glaucoma-causing TIGR/myocilin protein: Integrity of amino-terminal coiled-coil regions and olfactomedin homology domain is essential for extracellular adhesion and secretion. Exp Eye Res 2006; 82:1017-29. [PMID: 16466712 DOI: 10.1016/j.exer.2005.11.002] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2005] [Revised: 11/11/2005] [Accepted: 11/16/2005] [Indexed: 11/29/2022]
Abstract
TIGR/MYOC mutations account for 2-4% of the primary open-angle glaucoma (POAG) patients. More than 90% of the known mutations are located within its carboxy-terminus olfactomedin-homology (Olf) domain (amino acids (aa) 245-504). In vitro and in vivo studies showed that several Olf domain mutations prevented myocilin secretion. To investigate if intracellular sequestration was a characteristic feature shared by a majority of the mutations, we analyzed the secretion status of 36 myocilin variants. These encompassed 26 glaucoma-causing mutations and 10 non-disease associated or undefined polymorphisms. As several variants were found to be secreted, we tested for their adhesion to the extracellular matrix (ECM) and/or cell surface. Myocilin variants were generated by site-directed mutagenesis of a vector encoding the human MYOC cDNA. COS-7 or immortalized human trabecular meshwork cells were transfected with wild-type or mutated MYOC constructs. Myocilin levels were estimated by immunoprecipitation and/or immunoblotting. All variants showed identical behaviors in both cell lines; the truncated R46X polypeptide being the only variant which could not be detected in our assays. Of the 35 variants monitored, 20 remained sequestered intracellularly. All of them encoded disease-causing polypeptides carrying Olf domain mutations. Of the 15 variants secreted into the culture medium, six (6) were POAG mutants (of which three (3) located within the Olf domain) while the remaining nine (9) were non-disease causing or undefined polymorphisms. Three (3) of the six (6) secreted mutations caused familial POAG; these were the R126W, T377M and A427T mutants. Both, the T377M and A427T mutants located within the Olf domain. When cells were cultured at 30 degrees C, a process known to facilitate protein folding, 11 of the 20 sequestered mutants were released in the extracellular medium. Out of the 15 secreted variants tested for their adhesion to the ECM and/or cell surface, only the R82C and L95P polypeptides displayed loss of their adhesive properties. Deletion experiments revealed that the coiled-coil (aa 78-105) and leucine zipper (aa 114-183) motifs were essential for adhesion. These experiments demonstrate that intracellular sequestration might be the primary mechanism contributing to myocilin-related POAG as it was associated with more than 80% of the disease-causing mutants tested in our study. A second mechanism may involve abnormal interaction(s) between myocilin and ECM and/or cell surface proteins. Our data further revealed the importance of the olfactomedin-homology domain for myocilin secretion and the significant role of the N-terminal region for its extracellular interactions.
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Affiliation(s)
- Stéphane Gobeil
- Laboratory of Ocular Genetics and Genomics, Molecular Endocrinology and Oncology Research Center, Laval University Hospital (CHUL) Research Center, 2705 Laurier Boulevard, Room T3-67, Quebec City, Prov. of Québec, Canada G1V 4G2
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Abstract
PURPOSE OF REVIEW Glaucoma is one of the leading causes of irreversible blindness worldwide. Early glaucoma detection and treatment are currently the only known methods for preventing blindness and low vision resulting from this frequently asymptomatic disease. RECENT FINDINGS New technologies for detecting early glaucomatous damage are important in diagnosing optic nerve disease, not only in community screening settings but also in clinics. Imaging of the optic nerve head and macula and retinal nerve fiber layer analysis can provide quick, automated, and quantitative measurements in agreement with clinical estimates of optic disc structure and visual function. In the area of perimetry, frequency-doubling technology is a promising and feasible mass-screening method with reasonable sensitivity for detecting visual field loss. Central corneal thickness has emerged as a new risk factor for the development and progression of glaucoma, thereby complicating the role of tonometry and measurement of intraocular pressure as screening parameters for glaucoma. Along with technological advances, strides are also being made with public policy and legislative efforts to bring glaucoma onto the national and global health care agenda. These initiatives incorporate vision-screening goals into national disease prevention programs emphasizing the need for early glaucoma detection and treatment. SUMMARY Glaucoma awareness needs to be increased through better education, and compliance with follow-up care needs to be improved to decrease the economic and social costs from glaucoma. In addition, screening models need to be developed that will be effective in developing countries where the risk of blindness from glaucoma is highest.
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Affiliation(s)
- Constance Nduaguba
- Scheie Eye Institute, University of Pennsylvania Health System, Philadelphia, Pennsylvania, USA
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Kaur K, Reddy ABM, Mukhopadhyay A, Mandal AK, Hasnain SE, Ray K, Thomas R, Balasubramanian D, Chakrabarti S. Myocilin gene implicated in primary congenital glaucoma. Clin Genet 2005; 67:335-40. [PMID: 15733270 DOI: 10.1111/j.1399-0004.2005.00411.x] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Primary congenital glaucoma (PCG) has been associated with CYP1B1 gene (2p21), with a predominantly autosomal recessive mode of inheritance. Our earlier studies attributed CYP1B1 mutations to only 40% of Indian PCG cases. In this study, we included 72 such PCG cases where CYP1B1 mutations were detected in only 12 patients in heterozygous condition, implying involvement of other gene(s). On screening these patients for mutations in myocilin (MYOC), another glaucoma-associated gene, using denaturing high-performance liquid chromatography followed by sequencing, we identified a patient who was double heterozygous at CYP1B1 (c.1103G>A; Arg368His) and MYOC (c.144G>T; Gln48His) loci, suggesting a digenic mode of inheritance of PCG. In addition, we identified the same MYOC mutation, implicated for primary open angle glaucoma, in three additional PCG patients who did not harbor any mutation in CYP1B1. These observations suggest a possible role of MYOC in PCG, which might be mediated via digenic interaction with CYP1B1 and/or an yet unidentified locus associated with the disease.
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Affiliation(s)
- K Kaur
- Kallam Anji Reddy Molecular Genetics Laboratory, Hyderabad, Andhra Pradesh, India
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