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Stuart KV, Pasquale LR, Kang JH, Foster PJ, Khawaja AP. Towards modifying the genetic predisposition for glaucoma: An overview of the contribution and interaction of genetic and environmental factors. Mol Aspects Med 2023; 93:101203. [PMID: 37423164 PMCID: PMC10885335 DOI: 10.1016/j.mam.2023.101203] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Revised: 06/26/2023] [Accepted: 07/05/2023] [Indexed: 07/11/2023]
Abstract
Glaucoma, the leading cause of irreversible blindness worldwide, is a complex human disease, with both genetic and environmental determinants. The availability of large-scale, population-based cohorts and biobanks, combining genotyping and detailed phenotyping, has greatly accelerated research into the aetiology of glaucoma in recent years. Hypothesis-free genome-wide association studies have furthered our understanding of the complex genetic architecture underpinning the disease, while epidemiological studies have provided advances in the identification and characterisation of environmental risk factors. It is increasingly recognised that the combined effects of genetic and environmental factors may confer a disease risk that reflects a departure from the simple additive effect of the two. These gene-environment interactions have been implicated in a host of complex human diseases, including glaucoma, and have several important diagnostic and therapeutic implications for future clinical practice. Importantly, the ability to modify the risk associated with a particular genetic makeup promises to lead to personalised recommendations for glaucoma prevention, as well as novel treatment approaches in years to come. Here we provide an overview of genetic and environmental risk factors for glaucoma, as well as reviewing the evidence and discussing the implications of gene-environment interactions for the disease.
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Affiliation(s)
- Kelsey V Stuart
- NIHR Biomedical Research Centre, Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology, London, UK
| | - Louis R Pasquale
- Department of Ophthalmology, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Jae H Kang
- Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - Paul J Foster
- NIHR Biomedical Research Centre, Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology, London, UK
| | - Anthony P Khawaja
- NIHR Biomedical Research Centre, Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology, London, UK.
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2
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Cooke Bailey JN, Funk KL, Cruz LA, Waksmunski AR, Kinzy TG, Wiggs JL, Hauser MA. Diversity in Polygenic Risk of Primary Open-Angle Glaucoma. Genes (Basel) 2022; 14:111. [PMID: 36672852 PMCID: PMC9859496 DOI: 10.3390/genes14010111] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Revised: 12/22/2022] [Accepted: 12/29/2022] [Indexed: 12/31/2022] Open
Abstract
Glaucoma is the leading cause of irreversible blindness worldwide. Primary open-angle glaucoma (POAG), the most common glaucoma subtype, is more prevalent and severe in individuals of African ancestry. Unfortunately, this ancestral group has been historically under-represented among genetic studies of POAG. Moreover, both genetic and polygenic risk scores (GRS, PRS) that are typically based on genetic data from European-descent populations are not transferable to individuals without a majority of European ancestry. Given the aspirations of leveraging genetic information for precision medicine, GRS and PRS demonstrate clinical potential but fall short, in part due to the lack of diversity in these studies. Prioritizing diversity in the discovery of risk variants will improve the performance and utility of GRS and PRS-derived risk estimation for disease stratification, which could bring about earlier POAG intervention and treatment for a disease that often goes undetected until significant damage has occurred.
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Affiliation(s)
- Jessica N. Cooke Bailey
- Cleveland Institute for Computational Biology, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
- Department of Population and Quantitative Health Sciences, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - Kaitlyn L. Funk
- Cleveland Institute for Computational Biology, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
- Department of Population and Quantitative Health Sciences, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - Lauren A. Cruz
- Cleveland Institute for Computational Biology, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
- Department of Population and Quantitative Health Sciences, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - Andrea R. Waksmunski
- Cleveland Institute for Computational Biology, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
- Department of Population and Quantitative Health Sciences, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - Tyler G. Kinzy
- Cleveland Institute for Computational Biology, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
- Department of Population and Quantitative Health Sciences, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - Janey L. Wiggs
- Department of Ophthalmology, Massachusetts Eye and Ear, Harvard Medical School, Boston, MA 02115, USA
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3
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Burdon KP, Graham P, Hadler J, Hulleman JD, Pasutto F, Boese EA, Craig JE, Fingert JH, Hewitt AW, Siggs OM, Whisenhunt K, Young TL, Mackey DA, Dubowsky A, Souzeau E. Specifications of the ACMG/AMP variant curation guidelines for myocilin: Recommendations from the clingen glaucoma expert panel. Hum Mutat 2022; 43:2170-2186. [PMID: 36217948 PMCID: PMC9771967 DOI: 10.1002/humu.24482] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Revised: 09/02/2022] [Accepted: 10/06/2022] [Indexed: 01/25/2023]
Abstract
The standardization of variant curation criteria is essential for accurate interpretation of genetic results and clinical care of patients. The variant curation guidelines developed by the American College of Medical Genetics and Genomics (ACMG) and the Association for Molecular Pathology (AMP) in 2015 are widely used but are not gene specific. To address this issue, the Clinical Genome Resource (ClinGen) Variant Curation Expert Panels (VCEP) have been tasked with developing gene-specific variant curation guidelines. The Glaucoma VCEP was created to develop rule specifications for genes associated with primary glaucoma, including myocilin (MYOC), the most common cause of Mendelian glaucoma. Of the 28 ACMG/AMP criteria, the Glaucoma VCEP adapted 15 rules to MYOC and determined 13 rules not applicable. Key specifications included determining minor allele frequency thresholds, developing an approach to counting probands and segregations, and reviewing functional assays. The rules were piloted on 81 variants and led to a change in classification in 40% of those that were classified in ClinVar, with functional evidence influencing the classification of 18 variants. The standardized variant curation guidelines for MYOC provide a framework for the consistent application of the rules between laboratories, to improve MYOC genetic testing in the management of glaucoma.
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Affiliation(s)
- Kathryn P. Burdon
- Menzies Institute for Medical Research, University of Tasmania, Hobart, TAS, Australia
| | - Patricia Graham
- Menzies Institute for Medical Research, University of Tasmania, Hobart, TAS, Australia
- Centre for Ophthalmology and Vision Sciences, Lions Eye Institute, University of Western Australia, Perth, WA, Australia
| | - Johanna Hadler
- Department of Ophthalmology, Flinders University, Flinders Medical Centre, Adelaide, SA, Australia
- SA Pathology, Adelaide, SA, Australia
| | - John D. Hulleman
- Department of Ophthalmology, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Francesca Pasutto
- Institute of Human Genetics, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Erin A. Boese
- Department of Ophthalmology and Visual Sciences, University of Iowa, Iowa City, Iowa, USA
| | - Jamie E. Craig
- Department of Ophthalmology, Flinders University, Flinders Medical Centre, Adelaide, SA, Australia
| | - John H. Fingert
- Department of Ophthalmology and Visual Sciences, University of Iowa, Iowa City, Iowa, USA
| | - Alex W. Hewitt
- Menzies Institute for Medical Research, University of Tasmania, Hobart, TAS, Australia
| | - Owen M. Siggs
- Department of Ophthalmology, Flinders University, Flinders Medical Centre, Adelaide, SA, Australia
- Garvan Institute of Medical Research, Darlinghurst, NSW, Australia
| | - Kristina Whisenhunt
- Department of Ophthalmology and Visual Sciences, University of Wisconsin-Madison, Madison, WI, USA
| | - Terri L. Young
- Department of Ophthalmology and Visual Sciences, University of Wisconsin-Madison, Madison, WI, USA
| | - David A. Mackey
- Menzies Institute for Medical Research, University of Tasmania, Hobart, TAS, Australia
- Centre for Ophthalmology and Vision Sciences, Lions Eye Institute, University of Western Australia, Perth, WA, Australia
| | | | - Emmanuelle Souzeau
- Department of Ophthalmology, Flinders University, Flinders Medical Centre, Adelaide, SA, Australia
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4
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Tanji T, Cohen E, Shen D, Zhang C, Yu F, Coleman AL, Zheng JJ. Age at Glaucoma Diagnosis in Germline Myocilin Mutation Patients: Associations with Polymorphisms in Protein Stabilities. Genes (Basel) 2021; 12:genes12111802. [PMID: 34828408 PMCID: PMC8623052 DOI: 10.3390/genes12111802] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Revised: 11/08/2021] [Accepted: 11/10/2021] [Indexed: 12/02/2022] Open
Abstract
Glaucoma is the leading cause of irreversible blindness worldwide, with elevated intraocular pressure (IOP) as the only known modifiable risk factor. Trabecular meshwork (TM)-inducible myocilin (the MYOC gene) was the first to be identified and linked to juvenile and primary open-angle glaucoma. It has been suggested that mutations in the MYOC gene and the aggregation of mutant myocilin in the endoplasmic reticulum (ER) of TM may cause ER stress, resulting in a reduced outflow of aqueous humor and an increase in IOP. We selected 20 MYOC mutations with experimentally determined melting temperatures of mutated myocilin proteins. We included 40 published studies with at least one glaucoma patient with one of these 20 MYOC mutations and information on age at glaucoma diagnosis. Based on data from 458 patients, we found that a statistically significant but weak correlation was present between age and melting temperature based on various assumptions for age. We therefore conclude that genetic analysis of MYOC mutations alone cannot be used to accurately predict age at glaucoma diagnosis. However, it might be an important prognostic factor combined with other clinical factors for critical and early detection of glaucoma.
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Burdon KP. The utility of genomic testing in the ophthalmology clinic: A review. Clin Exp Ophthalmol 2021; 49:615-625. [PMID: 34231298 DOI: 10.1111/ceo.13970] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Accepted: 07/01/2021] [Indexed: 12/25/2022]
Abstract
Genomic testing assesses many genes in one test. It is often used in the diagnosis of heterogeneous single gene disorders where pathogenic variation in one of many genes are known to cause similar phenotypes, or where a clinical diagnosis is difficult to reach. In the ophthalmic setting, genomic testing can be used to diagnose several groups of diseases, including inherited retinal dystrophies, paediatric cataract, glaucoma and anterior segment dysgenesis and other syndromic developmental disorders with eye involvement. The testing can encompass several modalities ranging from whole genome sequencing to exome sequencing or targeted gene panels. The advantages to the patient of receiving a molecular diagnosis include an end to the diagnostic odyssey, determination of prognosis and clarification of treatment, access to accurate genetic counselling, and confirming eligibility for clinical trials or genetic specific therapies. Genomic testing is a powerful addition to the diagnosis and management of inherited eye disease.
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Affiliation(s)
- Kathryn P Burdon
- Menzies Institute for Medical Research, University of Tasmania, Hobart, Tasmania, Australia
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6
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Siggs OM, Han X, Qassim A, Souzeau E, Kuruvilla S, Marshall HN, Mullany S, Mackey DA, Hewitt AW, Gharahkhani P, MacGregor S, Craig JE. Association of Monogenic and Polygenic Risk With the Prevalence of Open-Angle Glaucoma. JAMA Ophthalmol 2021; 139:1023-1028. [PMID: 34264281 DOI: 10.1001/jamaophthalmol.2021.2440] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Importance Early diagnosis of open-angle glaucoma can lead to vision-saving treatment, and genetic variation is an increasingly powerful indicator in disease risk stratification. Objective To compare polygenic and monogenic variants in risk of glaucoma. Design, Setting, and Participants Clinical and genetic data were obtained for 2507 individuals from the Australian and New Zealand Registry of Advanced Glaucoma (ANZRAG) and 411 337 individuals in cross-sectional cohort studies including individuals of European ancestry in the UK Biobank. Recruitment to the UK Biobank occurred between 2006 and 2010, and data analysis occurred between September 2019 and August 2020. Main Outcomes and Measures Association of monogenic and polygenic variants with glaucoma risk. Results Individuals at high polygenic risk, defined as those in the top 5% of an unselected population, had a glaucoma risk (odds ratio [OR], 2.77; 95% CI, 2.58-2.98) comparable with the risk among individuals heterozygous for the MYOC p.Gln368Ter variant (OR 4.19; 95% CI, 3.25-5.31), which is the most common single-gene variant known to cause primary open-angle glaucoma. High polygenic risk was more than 6 times more common than MYOC p.Gln368Ter heterozygosity in ANZRAG (15.7% vs 2.6%) and more than 15 times more common in the general population (5.0% vs 0.32%). Within ANZRAG, high polygenic risk was associated with a mean (SD) age at glaucoma diagnosis that did not differ from the age at glaucoma diagnosis among individuals heterozygous for MYOC p.Gln368Ter (57.2 [14.2] vs 54.8 [13.6] years; P > .99). Conclusions and Relevance Monogenic and high polygenic risk were each associated with a more than 2.5-fold increased odds of developing glaucoma and an equivalent mean age at glaucoma diagnosis, with high polygenic risk more than 15 times more common in the general population.
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Affiliation(s)
- Owen M Siggs
- Department of Ophthalmology, Flinders University, Bedford Park, Australia.,Garvan Institute of Medical Research, Darlinghurst, Australia
| | - Xikun Han
- QIMR Berghofer Medical Research Institute, Brisbane, Australia
| | - Ayub Qassim
- Department of Ophthalmology, Flinders University, Bedford Park, Australia
| | - Emmanuelle Souzeau
- Department of Ophthalmology, Flinders University, Bedford Park, Australia
| | - Shilpa Kuruvilla
- Department of Ophthalmology, Flinders University, Bedford Park, Australia
| | - Henry N Marshall
- Department of Ophthalmology, Flinders University, Bedford Park, Australia
| | - Sean Mullany
- Department of Ophthalmology, Flinders University, Bedford Park, Australia
| | - David A Mackey
- Menzies Institute for Medical Research, University of Tasmania, Hobart, Australia.,Lions Eye Institute, Centre for Ophthalmology and Vision Sciences, University of Western Australia, Perth, Australia
| | - Alex W Hewitt
- Menzies Institute for Medical Research, University of Tasmania, Hobart, Australia.,Centre for Eye Research Australia, University of Melbourne, Melbourne, Australia
| | | | | | - Jamie E Craig
- Department of Ophthalmology, Flinders University, Bedford Park, Australia
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7
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Qassim A, Souzeau E, Hollitt G, Hassall MM, Siggs OM, Craig JE. Risk Stratification and Clinical Utility of Polygenic Risk Scores in Ophthalmology. Transl Vis Sci Technol 2021; 10:14. [PMID: 34111261 PMCID: PMC8114010 DOI: 10.1167/tvst.10.6.14] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Accepted: 02/19/2021] [Indexed: 11/24/2022] Open
Abstract
Translational Relevance Common genetic variants can be used to effectively stratify the risk of disease development and progression and may be used to guide screening, triaging, monitoring, or treatment thresholds.
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Affiliation(s)
- Ayub Qassim
- Department of Ophthalmology, Flinders University, Flinders Medical Centre, Bedford Park, Australia
| | - Emmanuelle Souzeau
- Department of Ophthalmology, Flinders University, Flinders Medical Centre, Bedford Park, Australia
| | - Georgie Hollitt
- Department of Ophthalmology, Flinders University, Flinders Medical Centre, Bedford Park, Australia
| | - Mark M. Hassall
- Department of Ophthalmology, Flinders University, Flinders Medical Centre, Bedford Park, Australia
| | - Owen M. Siggs
- Department of Ophthalmology, Flinders University, Flinders Medical Centre, Bedford Park, Australia
| | - Jamie E. Craig
- Department of Ophthalmology, Flinders University, Flinders Medical Centre, Bedford Park, Australia
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8
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Han X, Hewitt AW, MacGregor S. Predicting the Future of Genetic Risk Profiling of Glaucoma: A Narrative Review. JAMA Ophthalmol 2021; 139:224-231. [PMID: 33331888 DOI: 10.1001/jamaophthalmol.2020.5404] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Importance Glaucoma is the world's leading cause of irreversible blindness. Primary open-angle glaucoma (POAG) is typically asymptomatic early in the disease process, and unfortunately, many are diagnosed too late to prevent vision loss. Observations Genome-wide association studies, which evaluate the association between genetic variants and phenotype across the genome, have mapped many genes for POAG. As well as uncovering new biology, genetic information can be combined into a polygenic risk score (PRS), which aggregates an individual's disease risk over many genetic variants. In this nonsystematic review, performed from June 21, 2019, to October 1, 2020, we address a series of questions to explain the challenges and opportunities in translating genetic discoveries in POAG. We summarize what is known about POAG genetics and how its endophenotypes, such as intraocular pressure or cup-disc ratio, can help with prediction. We discuss the sample sizes available and how increases in the future may have an effect on the utility of prediction approaches. We explore particular scenarios, such as the use of PRS in risk stratification, and applications for individuals who are particularly high risk for POAG as a result of them carrying both a high penetrance mutation and an unfavorable PRS. Finally, we discuss the issue of equity in applying these tests and the prospects for prediction for people from various ancestry groups. The cost-effectiveness evaluation of glaucoma PRS in direct-to-consumer genetic testing and across different ancestry groups is warranted in future research. Conclusions and Relevance Advances in glaucoma genetics have opened the door for risk stratification based on genetic risk predictions. The PRS approach has shown good promise in predicting who will be at highest risk of POAG, which could improve outcomes if these predictions can be acted on to result in improved clinical outcomes.
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Affiliation(s)
- Xikun Han
- QIMR Berghofer Medical Research Institute, Brisbane, Australia.,School of Medicine, University of Queensland, St Lucia, Brisbane, Australia
| | - Alex W Hewitt
- Menzies Institute for Medical Research, University of Tasmania, Tasmania, Australia.,Centre for Eye Research Australia, University of Melbourne, Australia
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Abstract
IMPORTANCE Glaucoma is the most common cause of irreversible blindness worldwide. Many patients with glaucoma are asymptomatic early in the disease course. Primary care clinicians should know which patients to refer to an eye care professional for a complete eye examination to check for signs of glaucoma and to determine what systemic conditions or medications can increase a patient's risk of glaucoma. Open-angle and narrow-angle forms of glaucoma are reviewed, including a description of the pathophysiology, risk factors, screening, disease monitoring, and treatment options. OBSERVATIONS Glaucoma is a chronic progressive optic neuropathy, characterized by damage to the optic nerve and retinal nerve fiber layer, that can lead to permanent loss of peripheral or central vision. Intraocular pressure is the only known modifiable risk factor. Other important risk factors include older age, nonwhite race, and a family history of glaucoma. Several systemic medical conditions and medications including corticosteroids, anticholinergics, certain antidepressants, and topiramate may predispose patients to glaucoma. There are 2 broad categories of glaucoma, open-angle and angle-closure glaucoma. Diagnostic testing to assess for glaucoma and to monitor for disease progression includes measurement of intraocular pressure, perimetry, and optical coherence tomography. Treatment of glaucoma involves lowering intraocular pressure. This can be achieved with various classes of glaucoma medications as well as laser and incisional surgical procedures. CONCLUSIONS AND RELEVANCE Vision loss from glaucoma can be minimized by recognizing systemic conditions and medications that increase a patient's risk of glaucoma and referring high-risk patients for a complete ophthalmologic examination. Clinicians should ensure that patients remain adherent with taking glaucoma medications and should monitor for adverse events from medical or surgical interventions used to treat glaucoma.
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Affiliation(s)
- Joshua D Stein
- W.K. Kellogg Eye Center, Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor
- Center for Eye Policy and Innovation, University of Michigan, Ann Arbor
- Department of Health Management and Policy, University of Michigan School of Public Health, Ann Arbor
| | - Anthony P Khawaja
- NIHR Biomedical Research Centre, Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology, London, United Kingdom
| | - Jennifer S Weizer
- W.K. Kellogg Eye Center, Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor
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Nagar A, Myers S, Kozareva D, Simcoe M, Hammond C. Cascade screening for glaucoma in high-risk family members of African-Caribbean glaucoma patients in an urban population in London. Br J Ophthalmol 2020; 106:376-380. [PMID: 33303425 PMCID: PMC8867287 DOI: 10.1136/bjophthalmol-2020-317373] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Revised: 10/17/2020] [Accepted: 11/11/2020] [Indexed: 11/05/2022]
Abstract
Background/aims Cascade screening has been used successfully in relatives of patients with inherited cancers and other genetic diseases to identify presymptomatic disease. This study was designed to examine if this approach would be successful in a high-risk group: first-degree relatives (FDR) of African-Caribbean glaucoma patients resident in London. Methods African-Caribbean patients (probands) with glaucoma from an inner London hospital setting in a deprived area were asked to disseminate personalised information to their FDR over the age of 30 and to arrange a free hospital-based screening. Data collected, including optical coherence tomography imaging, were reviewed by a glaucoma specialist and if glaucoma was diagnosed or suspected, local specialist referral via family doctor was made. Results 203 probands were recruited from glaucoma clinics. 248 suitable FDR were identified as potentially eligible to attend screening. 57 (23%) FDR made contact with the research team of whom 18 (7%) attended a subsequent screening visit. No patients were diagnosed with glaucoma; one participant was diagnosed as glaucoma suspect. Reasons for poor uptake included reluctance by probands to involve their family members, and retirees spending significant time abroad. Conclusion Cascade screening of FDR of African-Caribbean glaucoma patients in inner city London was unsuccessful. Research confidentiality guidance prohibiting research teams directly contacting family members was a barrier. Greater community engagement, community-based screening and permission to contact FDR directly might have improved uptake.
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Affiliation(s)
- Anindyt Nagar
- Department of Ophthalmology, St Thomas' Hospital, London, UK
| | - Sam Myers
- Academic Section of Ophthalmology, King's College London, London, UK
| | - Diana Kozareva
- Department of Ophthalmology, St Thomas' Hospital, London, UK.,Department of Twin Research and Genetic Epidemiology, King's College London, London, UK
| | - Mark Simcoe
- Academic Section of Ophthalmology, King's College London, London, UK.,Department of Twin Research and Genetic Epidemiology, King's College London, London, UK
| | - Christopher Hammond
- Academic Section of Ophthalmology, King's College London, London, UK .,Department of Twin Research and Genetic Epidemiology, King's College London, London, UK
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11
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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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12
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Qassim A, Souzeau E, Siggs OM, Hassall MM, Han X, Griffiths HL, Frost NA, Vallabh NA, Kirwan JF, Menon G, Cree AJ, Galanopoulos A, Agar A, Healey PR, Graham SL, Landers J, Casson RJ, Gharahkhani P, Willoughby CE, Hewitt AW, Lotery AJ, MacGregor S, Craig JE. An Intraocular Pressure Polygenic Risk Score Stratifies Multiple Primary Open-Angle Glaucoma Parameters Including Treatment Intensity. Ophthalmology 2020; 127:901-907. [PMID: 32081492 DOI: 10.1016/j.ophtha.2019.12.025] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Revised: 12/19/2019] [Accepted: 12/20/2019] [Indexed: 11/27/2022] Open
Abstract
PURPOSE To examine the combined effects of common genetic variants associated with intraocular pressure (IOP) on primary open-angle glaucoma (POAG) phenotype using a polygenic risk score (PRS) stratification. DESIGN Cross-sectional study. PARTICIPANTS For the primary analysis, we examined the glaucoma phenotype of 2154 POAG patients enrolled in the Australian and New Zealand Registry of Advanced Glaucoma, including patients recruited from the United Kingdom. For replication, we examined an independent cohort of 624 early POAG patients. METHODS Using IOP genome-wide association study summary statistics, we developed a PRS derived solely from IOP-associated variants and stratified POAG patients into 3 risk tiers. The lowest and highest quintiles of the score were set as the low- and high-risk groups, respectively, and the other quintiles were set as the intermediate risk group. MAIN OUTCOME MEASURES Clinical glaucoma phenotype including maximum recorded IOP, age at diagnosis, number of family members affected by glaucoma, cup-to-disc ratio, visual field mean deviation, and treatment intensity. RESULTS A dose-response relationship was found between the IOP PRS and the maximum recorded IOP, with the high genetic risk group having a higher maximum IOP by 1.7 mmHg (standard deviation [SD], 0.62 mmHg) than the low genetic risk group (P = 0.006). Compared with the low genetic risk group, the high genetic risk group had a younger age of diagnosis by 3.7 years (SD, 1.0 years; P < 0.001), more family members affected by 0.46 members (SD, 0.11 members; P < 0.001), and higher rates of incisional surgery (odds ratio, 1.5; 95% confidence interval, 1.1-2.0; P = 0.007). No statistically significant difference was found in mean deviation. We further replicated the maximum IOP, number of family members affected by glaucoma, and treatment intensity (number of medications) results in the early POAG cohort (P ≤ 0.01). CONCLUSIONS The IOP PRS was correlated positively with maximum IOP, disease severity, need for surgery, and number of affected family members. Genes acting via IOP-mediated pathways, when considered in aggregate, have clinically important and reproducible implications for glaucoma patients and their close family members.
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Affiliation(s)
- Ayub Qassim
- Department of Ophthalmology, Flinders University, Flinders Medical Centre, Bedford Park, Australia.
| | - Emmanuelle Souzeau
- Department of Ophthalmology, Flinders University, Flinders Medical Centre, Bedford Park, Australia
| | - Owen M Siggs
- Department of Ophthalmology, Flinders University, Flinders Medical Centre, Bedford Park, Australia
| | - Mark M Hassall
- Department of Ophthalmology, Flinders University, Flinders Medical Centre, Bedford Park, Australia
| | - Xikun Han
- QIMR Berghofer Medical Research Institute, Brisbane, Australia
| | - Helen L Griffiths
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton, United Kingdom
| | - N Andrew Frost
- Department of Ophthalmology, Torbay Hospital, Torquay, Devon, United Kingdom
| | - Neeru A Vallabh
- Department of Eye and Vision Science, Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, United Kingdom
| | - James F Kirwan
- Department of Ophthalmology, Portsmouth Hospitals, Portsmouth, United Kingdom
| | - Geeta Menon
- Department of Ophthalmology, Frimley Park Hospital NHS Foundation Trust, Frimley, United Kingdom
| | - Angela J Cree
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton, United Kingdom
| | - Anna Galanopoulos
- South Australian Institute of Ophthalmology, Royal Adelaide Hospital, Adelaide, Australia
| | - Ashish Agar
- Department of Ophthalmology, Prince of Wales Hospital, Randwick, Australia
| | - Paul R Healey
- Centre for Vision Research, Westmead Institute for Medical Research, University of Sydney, Sydney, Australia
| | - Stuart L Graham
- Faculty of Medicine and Health Sciences, Macquarie University, Sydney, Australia
| | - John Landers
- Department of Ophthalmology, Flinders University, Flinders Medical Centre, Bedford Park, Australia
| | - Robert J Casson
- South Australian Institute of Ophthalmology, University of Adelaide, Adelaide, Australia
| | | | - Colin E Willoughby
- Biomedical Sciences Research Institute, Ulster University, Coleraine, United Kingdom; Royal Victoria Hospital, Belfast Health and Social Care Trust, Belfast, United Kingdom
| | - Alex W Hewitt
- Menzies Institute for Medical Research, University of Tasmania, Hobart, Australia
| | - Andrew J Lotery
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton, United Kingdom
| | | | - Jamie E Craig
- Department of Ophthalmology, Flinders University, Flinders Medical Centre, Bedford Park, Australia
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13
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Han X, Souzeau E, Ong JS, An J, Siggs OM, Burdon KP, Best S, Goldberg I, Healey PR, Graham SL, Ruddle JB, Mills RA, Landers J, Galanopoulos A, White AJR, Casson R, Mackey DA, Hewitt AW, Gharahkhani P, Craig JE, MacGregor S. Myocilin Gene Gln368Ter Variant Penetrance and Association With Glaucoma in Population-Based and Registry-Based Studies. JAMA Ophthalmol 2019; 137:28-35. [PMID: 30267046 DOI: 10.1001/jamaophthalmol.2018.4477] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Importance The p.Gln368Ter (rs74315329) risk allele in the myocilin gene (MYOC) was initially reported to have high penetrance in glaucoma registry-based studies, but much lower estimates were recently obtained from population-based studies. We investigated this disparity using data from Australia and the United Kingdom. Objectives To examine the penetrance and effect size of the MYOC p.Gln368Ter variant with glaucoma and ocular hypertension (OHT). Design, Setting, and Participants This cross-sectional study within the UK Biobank (UKBB) included participants of white British ancestry. Glaucoma cases were defined by International Classification of Diseases, Ninth Revision (ICD-9) and Tenth Revision (ICD-10) diagnoses and self-reported questionnaires. Carriers of the MYOC p.Gln368Ter variant were identified using genotype imputation from arrays. In contrast, 2 Australian registry-based studies, the Australian and New Zealand Registry of Advanced Glaucoma and the Glaucoma Inheritance Study in Tasmania, ascertained glaucoma cases referred by eye care clinicians, with historic control participants recruited from other Australian studies. Samples were either directly sequenced or had genotypes determined by imputation (for the Australian registry and historic control participants). Recruitment to the UKBB occurred between 2006 and 2010, and data analysis occurred from September 2017 to July 2018. Main Outcomes and Measures The penetrance and odds ratio (OR) were estimated for the MYOC p.Gln368Ter variants in participants with glaucoma and OHT. Results A total of 411 337 UKBB participants of white British ancestry (mean [SD] age, 56.6 [8.0] years) were included, plus 3071 Australian registry and 6750 historic control participants. In the UKBB, the minor allele frequency of the MYOC p.Gln368Ter variant was 1 in 786 individuals (0.13%). The odds ratio of p.Gln368Ter in patients with primary open-angle glaucoma (POAG) was 6.76 (95% CI, 4.05-11.29); glaucoma (POAG, self-reported glaucoma, and unspecified glaucoma), 4.40 (95% CI, 3.38-5.71); OHT, 3.56 (95% CI, 2.53-4.92); and OHT and glaucoma combined, 4.18 (95% CI, 3.05-5.67). The penetrance of the MYOC p.Gln368Ter variant was 7.6% in patients with glaucoma, 24.3% in patients with OHT, and 30.8% in patients with OHT and glaucoma combined. In the Australian registry studies, the odds of MYOC p.Gln368Ter variant were 12.16 (95% CI, 6.34-24.97) in patients with advanced glaucoma and 3.97 (95% CI, 1.55-9.75) in those with nonadvanced glaucoma; the penetrance of glaucoma was 56.1%, and penetrance in those considered to have glaucoma or be glaucoma suspects was 69.5%. Conclusions and Relevance The MYOC p.Gln368Ter variant confers a very high-risk effect size for advanced glaucoma; the risk is lower in nonadvanced glaucoma and OHT. In the general population sample, approximately 50% of MYOC p.Gln368Ter carriers 65 years and older had glaucoma or OHT, with higher prevalence in the Australian registry studies.
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Affiliation(s)
- Xikun Han
- Statistical Genetics, QIMR Berghofer Medical Research Institute, Brisbane, Australia.,School of Medicine, University of Queensland, St Lucia, Brisbane, Australia
| | - Emmanuelle Souzeau
- Department of Ophthalmology, Flinders University, Flinders Medical Centre, Adelaide, Australia
| | - Jue-Sheng Ong
- Statistical Genetics, QIMR Berghofer Medical Research Institute, Brisbane, Australia.,School of Medicine, University of Queensland, St Lucia, Brisbane, Australia
| | - Jiyuan An
- Statistical Genetics, QIMR Berghofer Medical Research Institute, Brisbane, Australia
| | - Owen M Siggs
- Department of Ophthalmology, Flinders University, Flinders Medical Centre, Adelaide, Australia
| | - Kathryn P Burdon
- Department of Ophthalmology, Flinders University, Flinders Medical Centre, Adelaide, Australia.,Menzies Institute for Medical Research, University of Tasmania, Hobart, Australia
| | - Stephen Best
- Eye Department, Greenlane Clinical Centre, Auckland District Health Board, Auckland, New Zealand
| | - Ivan Goldberg
- Discipline of Ophthalmology, Sydney Eye Hospital, University of Sydney, Sydney, Australia
| | - Paul R Healey
- Discipline of Ophthalmology, Sydney Eye Hospital, University of Sydney, Sydney, Australia.,Centre for Vision Research, Westmead Institute for Medical Research, University of Sydney, Sydney, Australia
| | - Stuart L Graham
- Discipline of Ophthalmology, Sydney Eye Hospital, University of Sydney, Sydney, Australia.,Ophthalmology and Vision Science, Faculty of Medicine and Human Sciences, Macquarie University, Australia
| | - Jonathan B Ruddle
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, University of Melbourne, Melbourne, Australia.,Ophthalmology, University of Melbourne, Department of Surgery, Melbourne, Australia.,Department of Ophthalmology, Royal Children's Hospital, Melbourne, Australia
| | - Richard A Mills
- Department of Ophthalmology, Flinders University, Flinders Medical Centre, Adelaide, Australia
| | - John Landers
- Department of Ophthalmology, Flinders University, Flinders Medical Centre, Adelaide, Australia
| | - Anna Galanopoulos
- South Australian Institute of Ophthalmology, Royal Adelaide Hospital, University of Adelaide, Adelaide, Australia
| | - Andrew J R White
- Centre for Vision Research, Westmead Institute for Medical Research, University of Sydney, Sydney, Australia
| | - Robert Casson
- South Australian Institute of Ophthalmology, Royal Adelaide Hospital, University of Adelaide, Adelaide, Australia
| | - David A Mackey
- Menzies Institute for Medical Research, University of Tasmania, Hobart, Australia.,Centre for Ophthalmology and Visual Sciences, Lions Eye Institute, University of Western Australia, Perth, Australia
| | - Alex W Hewitt
- Menzies Institute for Medical Research, University of Tasmania, Hobart, Australia.,Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, University of Melbourne, Melbourne, Australia
| | - Puya Gharahkhani
- Statistical Genetics, QIMR Berghofer Medical Research Institute, Brisbane, Australia
| | - Jamie E Craig
- Department of Ophthalmology, Flinders University, Flinders Medical Centre, Adelaide, Australia
| | - Stuart MacGregor
- Statistical Genetics, QIMR Berghofer Medical Research Institute, Brisbane, Australia
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14
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Choquet H, Wiggs JL, Khawaja AP. Clinical implications of recent advances in primary open-angle glaucoma genetics. Eye (Lond) 2019; 34:29-39. [PMID: 31645673 DOI: 10.1038/s41433-019-0632-7] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Accepted: 09/25/2019] [Indexed: 12/14/2022] Open
Abstract
Over the last decade, genetic studies, including genome-wide association studies (GWAS), have accelerated the discovery of genes and genomic regions contributing to primary open-angle glaucoma (POAG), a leading cause of irreversible vision loss. Here, we review the findings of genetic studies of POAG published in English prior to September 2019. In total, 74 genomic regions have been associated at a genome-wide level of significance with POAG susceptibility. Recent POAG GWAS provide not only insight into global and ethnic-specific genetic risk factors for POAG susceptibility across populations of diverse ancestry, but also important functional insights underlying biological mechanisms of glaucoma pathogenesis. In this review, we also summarize the genetic overlap between POAG, glaucoma endophenotypes, such as intraocular pressure and vertical cup-disc ratio (VCDR), and other eye disorders. We also discuss approaches recently developed to increase power for POAG locus discovery and to predict POAG risk. Finally, we discuss the recent development of POAG gene-based therapies and future strategies to treat glaucoma effectively. Understanding the genetic architecture of POAG is essential for an earlier diagnosis of this common eye disorder, predictive testing of at-risk patients, and design of gene-based targeted medical therapies none of which are currently available.
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Affiliation(s)
- Hélène Choquet
- Division of Research, Kaiser Permanente Northern California (KPNC), Oakland, CA, 94612, USA.
| | - Janey L Wiggs
- Department of Ophthalmology, Harvard Medical School, Massachusetts Eye and Ear Infirmary, Boston, MA, USA
| | - Anthony P Khawaja
- NIHR Biomedical Research Centre, Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology, London, UK
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15
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Affiliation(s)
- John H. Fingert
- Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa, Iowa City
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16
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Affiliation(s)
- Timothy E. Yap
- Imperial College Healthcare NHS Trust (ICHNT), The Western Eye Hospital, London, UK
- The Imperial College Ophthalmic Research Group (ICORG), Imperial College London, London, UK
| | - Eduardo M. Normando
- Imperial College Healthcare NHS Trust (ICHNT), The Western Eye Hospital, London, UK
- The Imperial College Ophthalmic Research Group (ICORG), Imperial College London, London, UK
| | - Maria Francesca Cordeiro
- Imperial College Healthcare NHS Trust (ICHNT), The Western Eye Hospital, London, UK
- The Imperial College Ophthalmic Research Group (ICORG), Imperial College London, London, UK
- Department of Visual Neuroscience, Glaucoma and Retinal Neurodegeneration Group, UCL Institute of Ophthalmology, London, UK
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17
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Are we ready for genetic testing for primary open-angle glaucoma? Eye (Lond) 2018; 32:877-883. [PMID: 29379103 DOI: 10.1038/s41433-017-0011-1] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2017] [Revised: 12/14/2017] [Accepted: 12/16/2017] [Indexed: 11/08/2022] Open
Abstract
Following a dramatic reduction in the cost of genotyping technology in recent years, there have been significant advances in the understanding of the genetic basis of glaucoma. Glaucoma patients represent around a quarter of all outpatient activity in the UK hospital eye service and are a huge burden for the National Health Service. A potential benefit of genetic testing is personalised glaucoma management, allowing direction of our limited healthcare resources to the glaucoma patients who most need it. Our review aims to summarise recent discoveries in the field of glaucoma genetics and to discuss their potential clinical utility. While genome-wide association studies have now identified over ten genes associated with primary open-angle glaucoma (POAG), individually, variants in these genes are not predictive of POAG in populations. There are data suggesting some of these POAG variants are associated with conversion from ocular hypertension to POAG and visual field progression among POAG patients. However, these studies have not been replicated yet and such genetic testing is not currently justified in clinical care. In contrast, genetic testing for inherited early-onset disease in relatives of POAG patients with a known genetic mutation is of clear benefit; this can support either regular review to commence early treatment when the disease develops, or discharge from ophthalmology services of relatives who do not carry the mutation. Genetic testing for POAG at a population level is not currently justified.
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18
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Wiggs JL, Pasquale LR. Genetics of glaucoma. Hum Mol Genet 2017; 26:R21-R27. [PMID: 28505344 DOI: 10.1093/hmg/ddx184] [Citation(s) in RCA: 217] [Impact Index Per Article: 31.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2017] [Accepted: 05/08/2017] [Indexed: 12/15/2022] Open
Abstract
Genetic and genomic studies, including genome-wide association studies (GWAS) have accelerated the discovery of genes contributing to glaucoma, the leading cause of irreversible blindness world-wide. Glaucoma can occur at all ages, with Mendelian inheritance typical for the rare early onset disease (before age 40) and complex inheritance evident in common adult-onset forms of disease. Recent studies have suggested possible therapeutic targets for some patients with early-onset glaucoma based on the molecular and cellular events caused by MYOC, OPTN and TBK1 mutations. Diagnostic genetic tests using early-onset glaucoma genes are also proving useful for pre-symptomatic disease detection and genetic counseling. Recent GWAS completed for three types of common adult-onset glaucoma have identified novel loci for POAG (primary-open-angle glaucoma) (ABCA1, AFAP1, GMDS, PMM2, TGFBR3, FNDC3B, ARHGEF12, GAS7, FOXC1, ATXN2, TXNRD2); PACG (primary angle-closure glaucoma (EPDR1, CHAT, GLIS3, FERMT2, DPM2-FAM102); and exfoliation syndrome (XFS) glaucoma (CACNA1A). In total sixteen genomic regions have been associated with POAG (including the normal tension glaucoma (NTG) subgroup), 8 with PACG and 2 with XFS. These studies are defining important biological pathways and processes that contribute to disease pathogenesis.
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Affiliation(s)
- Janey L Wiggs
- Department of Ophthalmology, Harvard Medical School, Massachusetts Eye and Ear, Boston, MA 02114, USA
| | - Louis R Pasquale
- Department of Ophthalmology, Harvard Medical School, Massachusetts Eye and Ear, Boston, MA 02114, USA.,Channing Division of Network Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02114, USA
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19
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Hill SE, Nguyen E, Donegan RK, Patterson-Orazem AC, Hazel A, Gumbart JC, Lieberman RL. Structure and Misfolding of the Flexible Tripartite Coiled-Coil Domain of Glaucoma-Associated Myocilin. Structure 2017; 25:1697-1707.e5. [PMID: 29056483 PMCID: PMC5685557 DOI: 10.1016/j.str.2017.09.008] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2017] [Revised: 08/07/2017] [Accepted: 09/18/2017] [Indexed: 01/15/2023]
Abstract
Glaucoma-associated myocilin is a member of the olfactomedins, a protein family involved in neuronal development and human diseases. Molecular studies of the myocilin N-terminal coiled coil demonstrate a unique tripartite architecture: a Y-shaped parallel dimer-of-dimers with distinct tetramer and dimer regions. The structure of the dimeric C-terminal 7-heptad repeats elucidates an unexpected repeat pattern involving inter-strand stabilization by oppositely charged residues. Molecular dynamics simulations reveal an alternate accessible conformation in which the terminal inter-strand disulfide limits the extent of unfolding and results in a kinked configuration. By inference, full-length myocilin is also branched, with two pairs of C-terminal olfactomedin domains. Selected variants within the N-terminal region alter the apparent quaternary structure of myocilin but do so without compromising stability or causing aggregation. In addition to increasing our structural knowledge of naturally occurring extracellular coiled coils and biomedically important olfactomedins, this work broadens the scope of protein misfolding in the pathogenesis of myocilin-associated glaucoma.
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Affiliation(s)
- Shannon E Hill
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Elaine Nguyen
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Rebecca K Donegan
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | | | - Anthony Hazel
- School of Physics, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - James C Gumbart
- School of Physics, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Raquel L Lieberman
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332, USA.
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20
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Khalil A, Al-Haddad C, Hariri H, Shibbani K, Bitar F, Kurban M, Nemer G, Arabi M. A Novel Mutation in FOXC1 in a Lebanese Family with Congenital Heart Disease and Anterior Segment Dysgenesis: Potential Roles for NFATC1 and DPT in the Phenotypic Variations. Front Cardiovasc Med 2017; 4:58. [PMID: 28979898 PMCID: PMC5611365 DOI: 10.3389/fcvm.2017.00058] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Accepted: 08/31/2017] [Indexed: 01/06/2023] Open
Abstract
Congenital heart diseases (CHDs) are still the leading cause of death in neonates. Anterior segment dysgenesis is a broad clinical phenotype that affects the normal development of the eye, leading in most of the cases to glaucoma which is still a major cause of blindness for children and adolescents. Despite tremendous insights gained from genetic studies, a clear genotype–phenotype correlation is still difficult to draw. In Lebanon, a small country with still a high rate of consanguineous marriages, there are little data on the epidemiology of glaucoma amongst children with or without CHD. We carried out whole exome sequencing (WES) on a family with anterior segment dysgenesis, and CHD composed of three affected children with glaucoma, two of them with structural cardiac defects and three healthy siblings. The results unravel a novel mutation in FOXC1 (p. R127H) segregating with the phenotype and inherited from the mother, who did not develop glaucoma. We propose a digenic model for glaucoma in this family by combining the FOXC1 variant with a missense variant inherited from the father in the dermatopontin (DPT) gene. We also unravel a novel NFATC1 missense mutation predicted to be deleterious and present only in the patient with a severe ocular and cardiac phenotype. This is the first report on FOXC1 using WES to genetically characterize a family with both ocular and cardiac malformations. Our results support the usage of such technology to have a better genotype–phenotype picture for Mendelian-inherited diseases for which expressivity and penetrance are still not answered.
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Affiliation(s)
- Athar Khalil
- Department of Biochemistry and Molecular Genetics, American University of Beirut, Beirut, Lebanon
| | | | - Hadla Hariri
- Department of Biochemistry and Molecular Genetics, American University of Beirut, Beirut, Lebanon
| | - Kamel Shibbani
- Department of Biochemistry and Molecular Genetics, American University of Beirut, Beirut, Lebanon
| | - Fadi Bitar
- Department of Pediatrics and Adolescent Medicine, American University of Beirut, Beirut, Lebanon
| | - Mazen Kurban
- Department of Biochemistry and Molecular Genetics, American University of Beirut, Beirut, Lebanon.,Department of Dermatology, American University of Beirut, Beirut, Lebanon.,Department of Dermatology, Columbia University, New York, NY, United States
| | - Georges Nemer
- Department of Biochemistry and Molecular Genetics, American University of Beirut, Beirut, Lebanon
| | - Mariam Arabi
- Department of Pediatrics and Adolescent Medicine, American University of Beirut, Beirut, Lebanon
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