1
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Wang EHH, Lin PH, Wu PL, Kang EYC, Liu L, Yeh LK, Chen KJ, Hsiao MC, Wang NK. Genetic underpinnings explored: OPA1 deletion and complex phenotypes on chromosome 3q29. BMC Med Genomics 2024; 17:94. [PMID: 38641846 PMCID: PMC11031983 DOI: 10.1186/s12920-024-01850-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2023] [Accepted: 03/26/2024] [Indexed: 04/21/2024] Open
Abstract
BACKGROUND Copy number variations (CNVs) have emerged as significant contributors to the elusive genetic causality of inherited eye diseases. In this study, we describe a case with optic atrophy and a brain aneurysm, in which a de novo CNV 3q29 deletion was identified. CASE PRESENTATION A 40-year-old female patient was referred to our department after undergoing aneurysm transcatheter arterial embolization for a brain aneurysm. She had no history of systemic diseases, except for unsatisfactory best-corrected visual acuity (BCVA) since elementary school. Electrophysiological tests confirmed the findings in retinal images, indicating optic nerve atrophy. Chromosomal microarray analysis revealed a de novo deletion spanning 960 kb on chromosome 3q29, encompassing OPA1 and six neighboring genes. Unlike previously reported deletions in this region associated with optic atrophy, neuropsychiatric disorders, and obesity, this patient displayed a unique combination of optic atrophy and a brain aneurysm. However, there is no causal relationship between the brain aneurysm and the CNV. CONCLUSION In conclusion, the optic atrophy is conclusively attributed to the OPA1 deletion, and the aneurysm could be a coincidental association. The report emphasizes the likelihood of underestimating OPA1 deletions due to sequencing technology limitations. Recognizing these constraints, healthcare professionals must acknowledge these limitations and consistently search for OPA1 variants/deletions in Autosomal Dominant Optic Atrophy (ADOA) patients with negative sequencing results. This strategic approach ensures a more comprehensive exploration of copy-number variations, ultimately enhancing diagnostic precision in the field of genetic disorders.
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Affiliation(s)
- Ethan Hung-Hsi Wang
- Department of Ophthalmology, Edward S. Harkness Eye Institute, Columbia University, New York, NY, USA
- College of Arts and Sciences, University of Miami, Coral Gables, FL, USA
| | - Pei-Hsuan Lin
- Department of Ophthalmology, Edward S. Harkness Eye Institute, Columbia University, New York, NY, USA
- Department of Ophthalmology, National Taiwan University Yunlin Branch, Yunlin, Taiwan
| | - Pei-Liang Wu
- Department of Ophthalmology, Edward S. Harkness Eye Institute, Columbia University, New York, NY, USA
- College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Eugene Yu-Chuan Kang
- Department of Ophthalmology, Edward S. Harkness Eye Institute, Columbia University, New York, NY, USA
- College of Medicine, Chang Gung University, Taoyuan, Taiwan
- Department of Ophthalmology, Linkou Medical Center, Chang Gung Memorial Hospital, Taoyuan, Taiwan
- Graduate Institute of Clinical Medical Sciences, College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Laura Liu
- Department of Ophthalmology, Linkou Medical Center, Chang Gung Memorial Hospital, Taoyuan, Taiwan
- School of Traditional Chinese Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Lung-Kun Yeh
- College of Medicine, Chang Gung University, Taoyuan, Taiwan
- Department of Ophthalmology, Linkou Medical Center, Chang Gung Memorial Hospital, Taoyuan, Taiwan
| | - Kuan-Jen Chen
- College of Medicine, Chang Gung University, Taoyuan, Taiwan
- Department of Ophthalmology, Linkou Medical Center, Chang Gung Memorial Hospital, Taoyuan, Taiwan
| | - Meng-Chang Hsiao
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, USA
| | - Nan-Kai Wang
- Department of Ophthalmology, Edward S. Harkness Eye Institute, Columbia University, New York, NY, USA.
- College of Medicine, Chang Gung University, Taoyuan, Taiwan.
- Department of Ophthalmology, Linkou Medical Center, Chang Gung Memorial Hospital, Taoyuan, Taiwan.
- Vagelos College of Physicians and Surgeons, Columbia University, New York, USA.
- Edward S. Harkness Eye Institute, Columbia University Irving Medical Center, Hammer Health Sciences Building, 701 W. 168th St, 10032, New York, NY, USA.
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2
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Khandia R, Pandey MK, Garg R, Khan AA, Baklanov I, Alanazi AM, Nepali P, Gurjar P, Choudhary OP. Molecular insights into codon usage analysis of mitochondrial fission and fusion gene: relevance to neurodegenerative diseases. Ann Med Surg (Lond) 2024; 86:1416-1425. [PMID: 38463054 PMCID: PMC10923317 DOI: 10.1097/ms9.0000000000001725] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2023] [Accepted: 01/05/2024] [Indexed: 03/12/2024] Open
Abstract
Mitochondrial dysfunction is the leading cause of neurodegenerative disorders like Alzheimer's disease and Parkinson's disease. Mitochondria is a highly dynamic organelle continuously undergoing the process of fission and fusion for even distribution of components and maintaining proper shape, number, and bioenergetic functionality. A set of genes governs the process of fission and fusion. OPA1, Mfn1, and Mfn2 govern fusion, while Drp1, Fis1, MIEF1, and MIEF2 genes control fission. Determination of specific molecular patterns of transcripts of these genes revealed the impact of compositional constraints on selecting optimal codons. AGA and CCA codons were over-represented, and CCC, GTC, TTC, GGG, ACG were under-represented in the fusion gene set. In contrast, CTG was over-represented, and GCG, CCG, and TCG were under-represented in the fission gene set. Hydropathicity analysis revealed non-polar protein products of both fission and fusion gene set transcripts. AGA codon repeats are an integral part of translational regulation machinery and present a distinct pattern of over-representation and under-representation in different transcripts within the gene sets, suggestive of selective translational force precisely controlling the occurrence of the codon. Out of six synonymous codons, five synonymous codons encoding for leucine were used differently in both gene sets. Hence, forces regulating the occurrence of AGA and five synonymous leucine-encoding codons suggest translational selection. A correlation of mutational bias with gene expression and codon bias and GRAVY and AROMA signifies the selection pressure in both gene sets, while the correlation of compositional bias with gene expression, codon bias, protein properties, and minimum free energy signifies the presence of compositional constraints. More than 25% of codons of both gene sets showed a significant difference in codon usage. The overall analysis shed light on molecular features of gene sets involved in fission and fusion.
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Affiliation(s)
| | - Megha Katare Pandey
- Translational Medicine Center, All India Institute of Medical Sciences, Bhopal
| | | | - Azmat Ali Khan
- Pharmaceutical Biotechnology Laboratory, Department of Pharmaceutical Chemistry, College of Pharmacy, King Saud University, Riyadh, Saudi Arabia
| | - Igor Baklanov
- Department of Philosophy, North Caucasus Federal University, Stavropol, Russia
| | - Amer M. Alanazi
- Pharmaceutical Biotechnology Laboratory, Department of Pharmaceutical Chemistry, College of Pharmacy, King Saud University, Riyadh, Saudi Arabia
| | - Prakash Nepali
- Government Medical Officer, Bhimad Primary Health Care Center, Government of Nepal, Tanahun, Nepal
| | - Pankaj Gurjar
- Centre for Global Health Research, Saveetha Medical College and Hospital, Saveetha Institute of Medical and Technical Sciences, Saveetha University, Chennai, Tamil Nadu, India
- Department of Science and Engineering, Novel Global Community Educational Foundation, Hebersham, NSW, Australia
| | - Om Prakash Choudhary
- Department of Veterinary Anatomy, College of Veterinary Science, Guru Angad Dev Veterinary and Animal Sciences University (GADVASU), Rampura Phul, Bathinda, Punjab, India
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3
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Sladen PE, Jovanovic K, Guarascio R, Ottaviani D, Salsbury G, Novoselova T, Chapple JP, Yu-Wai-Man P, Cheetham ME. Modelling autosomal dominant optic atrophy associated with OPA1 variants in iPSC-derived retinal ganglion cells. Hum Mol Genet 2022; 31:3478-3493. [PMID: 35652445 PMCID: PMC9558835 DOI: 10.1093/hmg/ddac128] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Revised: 05/11/2022] [Accepted: 05/26/2022] [Indexed: 11/14/2022] Open
Abstract
Autosomal dominant optic atrophy (DOA) is the most common inherited optic neuropathy, characterized by the preferential loss of retinal ganglion cells (RGCs), resulting in optic nerve degeneration and progressive bilateral central vision loss. More than 60% of genetically confirmed patients with DOA carry variants in the nuclear OPA1 gene, which encodes for a ubiquitously expressed, mitochondrial GTPase protein. OPA1 has diverse functions within the mitochondrial network, facilitating inner membrane fusion and cristae modelling, regulating mitochondrial DNA maintenance and coordinating mitochondrial bioenergetics. There are currently no licensed disease-modifying therapies for DOA and the disease mechanisms driving RGC degeneration are poorly understood. Here, we describe the generation of isogenic, heterozygous OPA1 null induced pluripotent stem cell (iPSC) (OPA1+/-) through clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 gene editing of a control cell line, in conjunction with the generation of DOA patient-derived iPSC carrying OPA1 variants, namely, the c.2708_2711delTTAG variant (DOA iPSC), and previously reported missense variant iPSC line (c.1334G>A, DOA plus [DOA]+ iPSC) and CRISPR/Cas9 corrected controls. A two-dimensional (2D) differentiation protocol was used to study the effect of OPA1 variants on iPSC-RGC differentiation and mitochondrial function. OPA1+/-, DOA and DOA+ iPSC showed no differentiation deficit compared to control iPSC lines, exhibiting comparable expression of all relevant markers at each stage of differentiation. OPA1+/- and OPA1 variant iPSC-RGCs exhibited impaired mitochondrial homeostasis, with reduced bioenergetic output and compromised mitochondrial DNA maintenance. These data highlight mitochondrial deficits associated with OPA1 dysfunction in human iPSC-RGCs, and establish a platform to study disease mechanisms that contribute to RGC loss in DOA, as well as potential therapeutic interventions.
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Affiliation(s)
- Paul E Sladen
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
| | | | | | - Daniele Ottaviani
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
- Department of Biology, University of Padua, and Veneto Institute of Molecular Medicine, Padua 35129, Italy
| | - Grace Salsbury
- Centre for Endocrinology, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, Charterhouse Square, London EC1M 6BQ, UK
| | - Tatiana Novoselova
- Centre for Endocrinology, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, Charterhouse Square, London EC1M 6BQ, UK
| | - J Paul Chapple
- Centre for Endocrinology, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, Charterhouse Square, London EC1M 6BQ, UK
| | - Patrick Yu-Wai-Man
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
- Moorfields Eye Hospital NHS Foundation Trust, London EC1V 2PD, UK
- Cambridge Eye Unit, Addenbrooke’s Hospital, Cambridge University Hospital, Cambridge CB2 0QQ, UK
- Cambridge Centre for Brain Repair and MRC Mitochondrial Biology Unit, Department of Clinical Neurosciences, University of Cambridge, Cambridge CB2 0PY, UK
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4
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Hu K, Zatyka M, Astuti D, Beer N, Dias RP, Kulkarni A, Ainsworth J, Wright B, Majander A, Yu-Wai-Man P, Williams D, Barrett T. WFS1 protein expression correlates with clinical progression of optic atrophy in patients with Wolfram syndrome. J Med Genet 2022; 59:65-74. [PMID: 34006618 PMCID: PMC8685651 DOI: 10.1136/jmedgenet-2020-107257] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Revised: 09/15/2020] [Accepted: 10/15/2020] [Indexed: 02/06/2023]
Abstract
BACKGROUND Wolfram syndrome (WFS) is a rare disorder characterised by childhood-onset diabetes mellitus and progressive optic atrophy. Most patients have variants in the WFS1 gene. We undertook functional studies of WFS1 variants and correlated these with WFS1 protein expression and phenotype. METHODS 9 patients with a clinical diagnosis of WFS were studied with quantitative PCR for markers of endoplasmic reticulum (ER) stress and immunoblotting of fibroblast protein extracts for WFS1 protein expression. Luciferase reporter assay was used to assess ATF-6 dependent unfolded protein response (UPR) activation. RESULTS 6 patients with compound heterozygous nonsense mutations in WFS1 had no detectable WFS1 protein expression; 3 patients with missense variants had 4%, 45% and 48% WFS1 protein expression. One of these also had an OPA1 mutation and was reclassified as autosomal dominant optic atrophy-plus syndrome. There were no correlations between ER stress marker mRNA and WFS1 protein expression. ERSE-luciferase reporter indicated activation of the ATF6 branch of UPR in two patients tested. Patients with partial WFS1 expression showed milder visual acuity impairment (asymptomatic or colour blind only), compared with those with absent expression (registered severe vision impaired) (p=0.04). These differences remained after adjusting for duration of optic atrophy. CONCLUSIONS Patients with WFS who have partial WFS1 protein expression present with milder visual impairment. This suggests a protective effect of partial WFS1 protein expression on the severity and perhaps progression of vision impairment and that therapies to increase residual WFS1 protein expression may be beneficial.
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Affiliation(s)
- Kun Hu
- Institute of Cancer and Genomic Sciences, University of Birmingham College of Medical and Dental Sciences, Birmingham, UK
| | - Malgorzata Zatyka
- Institute of Cancer and Genomic Sciences, University of Birmingham College of Medical and Dental Sciences, Birmingham, UK
| | - Dewi Astuti
- Institute of Cancer and Genomic Sciences, University of Birmingham College of Medical and Dental Sciences, Birmingham, UK
| | - Nicola Beer
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Oxford University, Oxford, Oxfordshire, UK
| | - Renuka P Dias
- Institute of Metabolism and Systems Research, University of Birmingham College of Medical and Dental Sciences, Birmingham, UK
| | - Archana Kulkarni
- Department of Ophthalmology, Birmingham Women's and Children's NHS Foundation Trust, Birmingham, UK
| | - John Ainsworth
- Department of Ophthalmology, Birmingham Women's and Children's NHS Foundation Trust, Birmingham, UK
| | - Benjamin Wright
- Department of Neurology, University Hospitals Birmingham NHS Foundation Trust, Birmingham, UK
| | - Anna Majander
- Department of Ophthalmology, Helsinki University Hospital, University of Helsinki Faculty of Medicine, Helsinki, Uusimaa, Finland
- National Institute for Health Research Biomedical Research Centre at Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology, London, Greater London, UK
| | - Patrick Yu-Wai-Man
- National Institute for Health Research Biomedical Research Centre at Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology, London, Greater London, UK
- Cambridge Centre for Brain Repair, University of Cambridge, Cambridge, Cambridgeshire, UK
| | - Denise Williams
- Department of Clinical Genetics, Birmingham Women's and Children's NHS Foundation Trust, Birmingham, Birmingham, UK
| | - Timothy Barrett
- Institute of Cancer and Genomic Sciences, University of Birmingham College of Medical and Dental Sciences, Birmingham, UK
- Department of Endocrinology, Birmingham Women's and Children's NHS Foundation Trust, Birmingham, UK
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5
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Strachan EL, Mac White-Begg D, Crean J, Reynolds AL, Kennedy BN, O'Sullivan NC. The Role of Mitochondria in Optic Atrophy With Autosomal Inheritance. Front Neurosci 2021; 15:784987. [PMID: 34867178 PMCID: PMC8634724 DOI: 10.3389/fnins.2021.784987] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Accepted: 10/22/2021] [Indexed: 11/13/2022] Open
Abstract
Optic atrophy (OA) with autosomal inheritance is a form of optic neuropathy characterized by the progressive and irreversible loss of vision. In some cases, this is accompanied by additional, typically neurological, extra-ocular symptoms. Underlying the loss of vision is the specific degeneration of the retinal ganglion cells (RGCs) which form the optic nerve. Whilst autosomal OA is genetically heterogenous, all currently identified causative genes appear to be associated with mitochondrial organization and function. However, it is unclear why RGCs are particularly vulnerable to mitochondrial aberration. Despite the relatively high prevalence of this disorder, there are currently no approved treatments. Combined with the lack of knowledge concerning the mechanisms through which aberrant mitochondrial function leads to RGC death, there remains a clear need for further research to identify the underlying mechanisms and develop treatments for this condition. This review summarizes the genes known to be causative of autosomal OA and the mitochondrial dysfunction caused by pathogenic mutations. Furthermore, we discuss the suitability of available in vivo models for autosomal OA with regards to both treatment development and furthering the understanding of autosomal OA pathology.
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Affiliation(s)
- Elin L Strachan
- UCD Conway Institute, University College Dublin, Dublin, Ireland.,UCD School of Biomolecular and Biomedical Science, University College Dublin, Dublin, Ireland
| | - Delphi Mac White-Begg
- UCD Conway Institute, University College Dublin, Dublin, Ireland.,UCD School of Veterinary Medicine, University College Dublin, Dublin, Ireland
| | - John Crean
- UCD Conway Institute, University College Dublin, Dublin, Ireland.,UCD School of Biomolecular and Biomedical Science, University College Dublin, Dublin, Ireland.,UCD Diabetes Complications Research Centre, Conway Institute of Biomolecular and Biomedical Science, University College Dublin, Dublin, Ireland
| | - Alison L Reynolds
- UCD Conway Institute, University College Dublin, Dublin, Ireland.,UCD School of Veterinary Medicine, University College Dublin, Dublin, Ireland
| | - Breandán N Kennedy
- UCD Conway Institute, University College Dublin, Dublin, Ireland.,UCD School of Biomolecular and Biomedical Science, University College Dublin, Dublin, Ireland
| | - Niamh C O'Sullivan
- UCD Conway Institute, University College Dublin, Dublin, Ireland.,UCD School of Biomolecular and Biomedical Science, University College Dublin, Dublin, Ireland
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6
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Milanowski P, Kosior-Jarecka E, Łukasik U, Wróbel-Dudzińska D, Milanowska J, Khor CC, Aung T, Kocki J, Żarnowski T. Associations between OPA1, MFN1, and MFN2 polymorphisms and primary open angle glaucoma in Polish participants of European ancestry. Ophthalmic Genet 2021; 43:42-47. [PMID: 34425738 DOI: 10.1080/13816810.2021.1970197] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
BACKGROUND Glaucomatous optic nerve damage is caused by selective death of retinal ganglion cells (RGCs). Another condition with underlying loss of RGCs is autosomal dominant optic atrophy (ADOA). Majority of ADOA patients have mutations in OPA1, gene responsible for mitochondrial fusion final steps. Clinical resemblance between the two diseases make genes involved in mitochondrial fusion good candidates as glaucoma genes. In this study, we investigated if selected polymorphisms of OPA1, MFN1, and MFN2 were associated with glaucoma in Polish population. METHODS Four OPA1 (rs166850, rs10451941, rs7624750, rs9851685), one MFN1 (rs2111534), and two MFN2 (rs873458, rs2295281) single nucleotide polymorphisms were investigated in 304 primary open angle glaucoma patients (204 with normal tension glaucoma, 100 with high-tension glaucoma) and 258 control subjects using RT-PCR method. RESULTS There was a significant difference in genotype frequencies of rs9851685 and rs2111534 polymorphisms between glaucoma patients and control subjects. Several genotype combinations comprising SNPs at OPA1 and MFN1 were significantly differently distributed in a three-way comparison between controls, patients with NTG and patients with HTG. None of the studied MFN2 polymorphisms was significantly associated with HTG or NTG. CONCLUSIONS In studied population, genotype CC and allele C of rs9851685 OPA1 polymorphism are NTG risk factors, whereas TT genotype and T allele of this polymorphism are protective factors against NTG. Genotype GA of rs2111534 MFN1 polymorphism is an HTG risk factor and AA genotype of this polymorphism is a protective factor against HTG. Several OPA1 and MFN2 genotype combinations are significantly associated with either increased or decreased risk of glaucoma in this population.
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Affiliation(s)
- Piotr Milanowski
- Department of Diagnostics and Microsurgery of Glaucoma, Medical University of Lublin, Lublin, Poland
| | - Ewa Kosior-Jarecka
- Department of Diagnostics and Microsurgery of Glaucoma, Medical University of Lublin, Lublin, Poland
| | - Urszula Łukasik
- Department of Diagnostics and Microsurgery of Glaucoma, Medical University of Lublin, Lublin, Poland
| | - Dominika Wróbel-Dudzińska
- Department of Diagnostics and Microsurgery of Glaucoma, Medical University of Lublin, Lublin, Poland
| | - Joanna Milanowska
- Department of Applied Psychology, Medical University of Lublin, Lublin, Poland
| | - Chiea Chuen Khor
- Laboratory of Complex Disease Genetics, Genome Institute of Singapore, Singapore
| | - Tin Aung
- Singapore Eye Research Institute, Singapore National Eye Center, Singapore
| | - Janusz Kocki
- Department of Clinical Genetics, Medical University of Lublin, Lublin, Poland
| | - Tomasz Żarnowski
- Department of Diagnostics and Microsurgery of Glaucoma, Medical University of Lublin, Lublin, Poland
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7
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Weisschuh N, Schimpf-Linzenbold S, Mazzola P, Kieninger S, Xiao T, Kellner U, Neuhann T, Kelbsch C, Tonagel F, Wilhelm H, Kohl S, Wissinger B. Mutation spectrum of the OPA1 gene in a large cohort of patients with suspected dominant optic atrophy: Identification and classification of 48 novel variants. PLoS One 2021; 16:e0253987. [PMID: 34242285 PMCID: PMC8270428 DOI: 10.1371/journal.pone.0253987] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Accepted: 06/17/2021] [Indexed: 12/18/2022] Open
Abstract
Autosomal dominant optic atrophy is one of the most common inherited optic neuropathies. This disease is genetically heterogeneous, but most cases are due to pathogenic variants in the OPA1 gene: depending on the population studied, 32–90% of cases harbor pathogenic variants in this gene. The aim of this study was to provide a comprehensive overview of the entire spectrum of likely pathogenic variants in the OPA1 gene in a large cohort of patients. Over a period of 20 years, 755 unrelated probands with a diagnosis of bilateral optic atrophy were referred to our laboratory for molecular genetic investigation. Genetic testing of the OPA1 gene was initially performed by a combined analysis using either single-strand conformation polymorphism or denaturing high performance liquid chromatography followed by Sanger sequencing to validate aberrant bands or melting profiles. The presence of copy number variations was assessed using multiplex ligation-dependent probe amplification. Since 2012, genetic testing was based on next-generation sequencing platforms. Genetic screening of the OPA1 gene revealed putatively pathogenic variants in 278 unrelated probands which represent 36.8% of the entire cohort. A total of 156 unique variants were identified, 78% of which can be considered null alleles. Variant c.2708_2711del/p.(V903Gfs*3) was found to constitute 14% of all disease-causing alleles. Special emphasis was placed on the validation of splice variants either by analyzing cDNA derived from patients´ blood samples or by heterologous splice assays using minigenes. Splicing analysis revealed different aberrant splicing events, including exon skipping, activation of exonic or intronic cryptic splice sites, and the inclusion of pseudoexons. Forty-eight variants that we identified were novel. Nine of them were classified as pathogenic, 34 as likely pathogenic and five as variant of uncertain significance. Our study adds a significant number of novel variants to the mutation spectrum of the OPA1 gene and will thereby facilitate genetic diagnostics of patients with suspected dominant optic atrophy.
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Affiliation(s)
- Nicole Weisschuh
- Institute for Ophthalmic Research, Centre for Ophthalmology, University of Tübingen, Tübingen, Germany
| | - Simone Schimpf-Linzenbold
- Institute for Ophthalmic Research, Centre for Ophthalmology, University of Tübingen, Tübingen, Germany.,CeGaT GmbH and Praxis für Humangenetik Tübingen, Tübingen, Germany
| | - Pascale Mazzola
- Institute of Medical Genetics and Applied Genomics, University of Tübingen, Tübingen, Germany
| | - Sinja Kieninger
- Institute for Ophthalmic Research, Centre for Ophthalmology, University of Tübingen, Tübingen, Germany
| | - Ting Xiao
- Institute for Ophthalmic Research, Centre for Ophthalmology, University of Tübingen, Tübingen, Germany
| | - Ulrich Kellner
- Zentrum für seltene Netzhauterkrankungen, AugenZentrum Siegburg, MVZ Augenärztliches Diagnostik- und Therapiecentrum Siegburg GmbH, Siegburg, Germany.,RetinaScience, Bonn, Germany
| | | | - Carina Kelbsch
- Centre for Ophthalmology, University Eye Hospital, University of Tübingen, Tübingen, Germany
| | - Felix Tonagel
- Centre for Ophthalmology, University Eye Hospital, University of Tübingen, Tübingen, Germany
| | - Helmut Wilhelm
- Centre for Ophthalmology, University Eye Hospital, University of Tübingen, Tübingen, Germany
| | - Susanne Kohl
- Institute for Ophthalmic Research, Centre for Ophthalmology, University of Tübingen, Tübingen, Germany
| | - Bernd Wissinger
- Institute for Ophthalmic Research, Centre for Ophthalmology, University of Tübingen, Tübingen, Germany
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8
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Lenaers G, Neutzner A, Le Dantec Y, Jüschke C, Xiao T, Decembrini S, Swirski S, Kieninger S, Agca C, Kim US, Reynier P, Yu-Wai-Man P, Neidhardt J, Wissinger B. Dominant optic atrophy: Culprit mitochondria in the optic nerve. Prog Retin Eye Res 2021; 83:100935. [PMID: 33340656 DOI: 10.1016/j.preteyeres.2020.100935] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Revised: 12/05/2020] [Accepted: 12/09/2020] [Indexed: 12/14/2022]
Abstract
Dominant optic atrophy (DOA) is an inherited mitochondrial disease leading to specific degeneration of retinal ganglion cells (RGCs), thus compromising transmission of visual information from the retina to the brain. Usually, DOA starts during childhood and evolves to poor vision or legal blindness, affecting the central vision, whilst sparing the peripheral visual field. In 20% of cases, DOA presents as syndromic disorder, with secondary symptoms affecting neuronal and muscular functions. Twenty years ago, we demonstrated that heterozygous mutations in OPA1 are the most frequent molecular cause of DOA. Since then, variants in additional genes, whose functions in many instances converge with those of OPA1, have been identified by next generation sequencing. OPA1 encodes a dynamin-related GTPase imported into mitochondria and located to the inner membrane and intermembrane space. The many OPA1 isoforms, resulting from alternative splicing of three exons, form complex homopolymers that structure mitochondrial cristae, and contribute to fusion of the outer membrane, thus shaping the whole mitochondrial network. Moreover, OPA1 is required for oxidative phosphorylation, maintenance of mitochondrial genome, calcium homeostasis and regulation of apoptosis, thus making OPA1 the Swiss army-knife of mitochondria. Understanding DOA pathophysiology requires the understanding of RGC peculiarities with respect to OPA1 functions. Besides the tremendous energy requirements of RGCs to relay visual information from the eye to the brain, these neurons present unique features related to their differential environments in the retina, and to the anatomical transition occurring at the lamina cribrosa, which parallel major adaptations of mitochondrial physiology and shape, in the pre- and post-laminar segments of the optic nerve. Three DOA mouse models, with different Opa1 mutations, have been generated to study intrinsic mechanisms responsible for RGC degeneration, and these have further revealed secondary symptoms related to mitochondrial dysfunctions, mirroring the more severe syndromic phenotypes seen in a subgroup of patients. Metabolomics analyses of cells, mouse organs and patient plasma mutated for OPA1 revealed new unexpected pathophysiological mechanisms related to mitochondrial dysfunction, and biomarkers correlated quantitatively to the severity of the disease. Here, we review and synthesize these data, and propose different approaches for embracing possible therapies to fulfil the unmet clinical needs of this disease, and provide hope to affected DOA patients.
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Affiliation(s)
- Guy Lenaers
- MitoLab Team, UMR CNRS 6015 - INSERM U1083, Institut MitoVasc, Angers University and Hospital, Angers, France.
| | - Albert Neutzner
- Department of Biomedicine, University Hospital Basel, University of Basel, Basel, Switzerland; Department of Ophthalmology University Hospital Basel, University of Basel, Basel, Switzerland.
| | - Yannick Le Dantec
- MitoLab Team, UMR CNRS 6015 - INSERM U1083, Institut MitoVasc, Angers University and Hospital, Angers, France
| | - Christoph Jüschke
- Human Genetics, Faculty VI - School of Medicine and Health Sciences, University of Oldenburg, Oldenburg, Germany
| | - Ting Xiao
- Molecular Genetics Laboratory, Institute for Ophthalmic Research, Center for Ophthalmology, University of Tübingen, Tübingen, Germany
| | - Sarah Decembrini
- Department of Biomedicine, University Hospital Basel, University of Basel, Basel, Switzerland; Department of Ophthalmology University Hospital Basel, University of Basel, Basel, Switzerland
| | - Sebastian Swirski
- Human Genetics, Faculty VI - School of Medicine and Health Sciences, University of Oldenburg, Oldenburg, Germany
| | - Sinja Kieninger
- Molecular Genetics Laboratory, Institute for Ophthalmic Research, Center for Ophthalmology, University of Tübingen, Tübingen, Germany
| | - Cavit Agca
- Molecular Biology, Genetics and Bioengineering Program, Sabanci University, Istanbul, Turkey; Nanotechnology Research and Application Center (SUNUM), Sabanci University, Istanbul, Turkey
| | - Ungsoo S Kim
- Kim's Eye Hospital, Seoul, South Korea; Cambridge Centre for Brain Repair and MRC Mitochondrial Biology Unit, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK; Cambridge Eye Unit, Addenbrooke's Hospital, Cambridge University Hospitals, Cambridge, UK; Moorfields Eye Hospital, London, UK
| | - Pascal Reynier
- MitoLab Team, UMR CNRS 6015 - INSERM U1083, Institut MitoVasc, Angers University and Hospital, Angers, France; Department of Biochemistry, University Hospital of Angers, Angers, France
| | - Patrick Yu-Wai-Man
- Cambridge Centre for Brain Repair and MRC Mitochondrial Biology Unit, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK; Cambridge Eye Unit, Addenbrooke's Hospital, Cambridge University Hospitals, Cambridge, UK; Moorfields Eye Hospital, London, UK; UCL Institute of Ophthalmology, University College London, London, UK
| | - John Neidhardt
- Human Genetics, Faculty VI - School of Medicine and Health Sciences, University of Oldenburg, Oldenburg, Germany; Research Center Neurosensory Science, University Oldenburg, Oldenburg, Germany.
| | - Bernd Wissinger
- Molecular Genetics Laboratory, Institute for Ophthalmic Research, Center for Ophthalmology, University of Tübingen, Tübingen, Germany.
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9
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Weisschuh N, Mazzola P, Heinrich T, Haack T, Wissinger B, Tonagel F, Kelbsch C. First submicroscopic inversion of the OPA1 gene identified in dominant optic atrophy - a case report. BMC MEDICAL GENETICS 2020; 21:236. [PMID: 33243194 PMCID: PMC7690134 DOI: 10.1186/s12881-020-01166-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/14/2020] [Accepted: 11/10/2020] [Indexed: 12/16/2022]
Abstract
Background Dominant optic atrophy (DOA) is an inherited optic neuropathy that mainly affects visual acuity, central visual fields and color vision due to a progressive loss of retinal ganglion cells and their axons that form the optic nerve. Approximately 45–90% of affected individuals with DOA harbor pathogenic variants in the OPA1 gene. The mutation spectrum of OPA1 comprises nonsense, canonical and non-canonical splice site, frameshift and missense as well as copy number variants, but intragenic inversions have not been reported so far. Case presentation We report a 33-year-old male with characteristic clinical features of DOA. Whole-genome sequencing identified a structural variant of 2.4 kb comprising an inversion of 937 bp at the OPA1 locus. Fine mapping of the breakpoints to single nucleotide level revealed that the structural variation was an inversion flanked by two deletions. As this rearrangement inverts the entire first exon of OPA1, it was classified as likely pathogenic. Conclusions We report the first DOA case harboring an inversion in the OPA1 gene. Our study demonstrates that copy-neutral genomic rearrangements have to be considered as a possible cause of disease in DOA cases. Supplementary Information The online version contains supplementary material available at 10.1186/s12881-020-01166-z.
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Affiliation(s)
- Nicole Weisschuh
- Institute for Ophthalmic Research, Centre for Ophthalmology, University of Tübingen, Tübingen, Germany.
| | - Pascale Mazzola
- Institute of Medical Genetics and Applied Genomics, University of Tübingen, Tübingen, Germany
| | - Tilman Heinrich
- Institute of Medical Genetics and Applied Genomics, University of Tübingen, Tübingen, Germany.,Centre for Rare Diseases, University of Tübingen, Tübingen, Germany
| | - Tobias Haack
- Institute of Medical Genetics and Applied Genomics, University of Tübingen, Tübingen, Germany.,Centre for Rare Diseases, University of Tübingen, Tübingen, Germany
| | - Bernd Wissinger
- Institute for Ophthalmic Research, Centre for Ophthalmology, University of Tübingen, Tübingen, Germany
| | - Felix Tonagel
- University Eye Hospital, Centre for Ophthalmology, University of Tübingen, Tübingen, Germany
| | - Carina Kelbsch
- University Eye Hospital, Centre for Ophthalmology, University of Tübingen, Tübingen, Germany
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10
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Zeng T, Liao L, Guo Y, Liu X, Xiong X, Zhang Y, Cen S, Li H, Wei S. Concurrent OPA1 mutation and chromosome 3q deletion leading to Behr syndrome: a case report. BMC Pediatr 2020; 20:420. [PMID: 32883255 PMCID: PMC7469303 DOI: 10.1186/s12887-020-02309-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Accepted: 08/20/2020] [Indexed: 12/02/2022] Open
Abstract
Background Optic atrophy 1 (OPA1) gene mutations are associated with dominantly inherited optic neuropathy resulting in a progressive loss of visual acuity. Compound heterozygous or homozygous variants that lead to severe phenotypes, including Behr syndrome, have been reported rarely. Case presentation Here, we present a 14-month-old boy with early onset optic atrophy, congenital cataracts, neuromuscular disorders, mental retardation, and developmental delay. Combined genetic testing, including whole exome sequencing (WES) and chromosomal microarray analysis, revealed a concurrent OPA1 variant (c.2189 T > C p.Leu730Ser) and de novo chromosome 3q deletion as pathogenic variants leading to the severe phenotype. Conclusions Our case is the first reporting a novel missense OPA1 variant co-occurring with a chromosomal microdeletion leading to a severe phenotype reminiscent of Behr syndrome. This expands the mutation spectrum of OPA1 and inheritance patterns of this disease.
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Affiliation(s)
- Ting Zeng
- Department of Child Healthcare, Liuzhou Maternity and Child Healthcare Hospital, 50 Boyuan Avenue, Liuzhou, 545616, China.,Key Laboratory of Developmental Disorders in Children, Liuzhou Maternity and Child Healthcare Hospital, 50 Boyuan Avenue, Liuzhou, 545616, China
| | - Linyan Liao
- Department of Child Healthcare, Liuzhou Maternity and Child Healthcare Hospital, 50 Boyuan Avenue, Liuzhou, 545616, China
| | - Yi Guo
- Department of Child Healthcare, Liuzhou Maternity and Child Healthcare Hospital, 50 Boyuan Avenue, Liuzhou, 545616, China
| | - Xuxu Liu
- Department of Child Healthcare, Liuzhou Maternity and Child Healthcare Hospital, 50 Boyuan Avenue, Liuzhou, 545616, China
| | - Xiaobo Xiong
- Department of Child Healthcare, Liuzhou Maternity and Child Healthcare Hospital, 50 Boyuan Avenue, Liuzhou, 545616, China
| | - Yu Zhang
- Department of Child Healthcare, Liuzhou Maternity and Child Healthcare Hospital, 50 Boyuan Avenue, Liuzhou, 545616, China.,Key Laboratory of Developmental Disorders in Children, Liuzhou Maternity and Child Healthcare Hospital, 50 Boyuan Avenue, Liuzhou, 545616, China
| | - Shi Cen
- Department of Child Healthcare, Liuzhou Maternity and Child Healthcare Hospital, 50 Boyuan Avenue, Liuzhou, 545616, China.,Key Laboratory of Developmental Disorders in Children, Liuzhou Maternity and Child Healthcare Hospital, 50 Boyuan Avenue, Liuzhou, 545616, China
| | - Honghui Li
- Department of Child Healthcare, Liuzhou Maternity and Child Healthcare Hospital, 50 Boyuan Avenue, Liuzhou, 545616, China.,Key Laboratory of Developmental Disorders in Children, Liuzhou Maternity and Child Healthcare Hospital, 50 Boyuan Avenue, Liuzhou, 545616, China
| | - Shuzhang Wei
- Department of Child Healthcare, Liuzhou Maternity and Child Healthcare Hospital, 50 Boyuan Avenue, Liuzhou, 545616, China. .,Key Laboratory of Developmental Disorders in Children, Liuzhou Maternity and Child Healthcare Hospital, 50 Boyuan Avenue, Liuzhou, 545616, China.
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11
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Ham M, Han J, Osann K, Smith M, Kimonis V. Meta-analysis of genotype-phenotype analysis of OPA1 mutations in autosomal dominant optic atrophy. Mitochondrion 2018; 46:262-269. [PMID: 30165240 DOI: 10.1016/j.mito.2018.07.006] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2018] [Revised: 05/20/2018] [Accepted: 07/31/2018] [Indexed: 01/21/2023]
Abstract
Autosomal Dominant Optic Atrophy (ADOA) is a neuro-ophthalmic disease characterized by progressive bilateral vision loss, pallor of the optic disc, central vision loss, and impairment of color vision. Additionally, a small percentage of patients experience hearing loss and ataxia, while recent studies suggest disruption of cardiac and neuromuscular functions. In order to obtain a better understanding of the genotype-phenotype correlation of the various mutations in the optic atrophy 1 (OPA1) gene, we obtained both clinical and genetic information of ADOA patients from published reports. We conducted a systematic review of published OPA1 literature and identified 408 individuals with confirmed OPA1 mutations, 120 of whom reported extra-ocular (ADOA 'plus') manifestations through their descriptions of visual and multi-systemic symptoms. Our results show that there is a significant variation in frequency of the specific exons involved between the ADOA classic and ADOA 'plus' patients. Classic ADOA groups were more likely to have mutations in exon 8 and 9, while ADOA 'plus' groups were more likely to have mutations in exons 14, 15 and 17. Additional comparisons revealed significant differences between mutation types/domains and specific ADOA 'plus' manifestations. We also found that individuals with maternally inherited OPA1 mutations were significantly more likely to develop 'plus' manifestations than those with paternally inherited mutations. Overall, this study provides novel information regarding genotype-phenotype correlations of ADOA which warrants additional recommendations added to the current clinical management of ADOA patients.
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Affiliation(s)
- Michelle Ham
- Division of Genetics and Genomic Medicine, Department of Pediatrics, University of California, Irvine, CA, USA
| | - Julia Han
- Division of Genetics and Genomic Medicine, Department of Pediatrics, University of California, Irvine, CA, USA
| | - Kathryn Osann
- Department of Medicine, Division of Hematology-Oncology, University of California, Irvine, CA, USA
| | - Moyra Smith
- Division of Genetics and Genomic Medicine, Department of Pediatrics, University of California, Irvine, CA, USA
| | - Virginia Kimonis
- Division of Genetics and Genomic Medicine, Department of Pediatrics, University of California, Irvine, CA, USA.
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12
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Li H, Jones EM, Li H, Yang L, Sun Z, Yuan Z, Chen R, Dong F, Sui R. Clinical and genetic features of eight Chinese autosomal-dominant optic atrophy pedigrees with six novel OPA1 pathogenic variants. Ophthalmic Genet 2018; 39:569-576. [PMID: 29952689 DOI: 10.1080/13816810.2018.1466337] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
BACKGROUND Autosomal-dominant optic atrophy (ADOA) is one of the most common types of inherited optic atrophy. We identify OPA1 pathogenic variants and assess the clinical features of a cohort of Chinese ADOA patients Materials and Methods: Detailed clinical evaluations were performed and genomic DNA was extracted from peripheral blood for all the participants. Sanger sequencing was used to analyze all exons and exon/intron junctions of OPA1 for eight pedigrees. Target exome capture plus next-generation sequencing (NGS) were applied for one atypical family with photophobia. Reverse transcription polymerase chain reaction was carried out to further characterize the mRNA change of selected splicing alteration. RESULTS All 17 patients had impaired vision and optic-disk pallor; however, the clinical severity varied markedly. Two patients complicated with hearing loss. Six novel and two reported pathogenic variants in OPA1 (GenBank Accession No. NM_130837.2) were identified including four nonsynonymous variants (c.2400T > G, c.1468T > C, c.1567A > G and c.1466T > C), two splicing variants (c.2984-1_2986delGAGA and c.2983 + 5G > A), one small deletion (c.2960_2968delGCGTTCAAC), and one small insertion (c.3009_3010insA). RNA analysis revealed the splicing variant c.2984-1_2986delGAGA caused small deletion of mRNA (r.2983_2988del). CONCLUSIONS ADOA patients presented variable clinical manifestations. Novel OPA1 pathogenic variants are the main genetic defect for Chinese ADOA cases. NGS may be a useful molecular testing tool for atypical ADOA.
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Affiliation(s)
- Huajin Li
- a Department of Ophthalmology , Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences , Beijing , China
| | - Evan M Jones
- b Department of Molecular and Human Genetics , Baylor College of Medicine , Houston , TX , USA
| | - Hui Li
- a Department of Ophthalmology , Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences , Beijing , China
| | - Lizhu Yang
- a Department of Ophthalmology , Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences , Beijing , China
| | - Zixi Sun
- a Department of Ophthalmology , Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences , Beijing , China
| | - Zhisheng Yuan
- a Department of Ophthalmology , Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences , Beijing , China
| | - Rui Chen
- b Department of Molecular and Human Genetics , Baylor College of Medicine , Houston , TX , USA
| | - Fangtian Dong
- a Department of Ophthalmology , Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences , Beijing , China
| | - Ruifang Sui
- a Department of Ophthalmology , Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences , Beijing , China
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13
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Bagli E, Zikou AK, Agnantis N, Kitsos G. Mitochondrial Membrane Dynamics and Inherited Optic Neuropathies. ACTA ACUST UNITED AC 2018; 31:511-525. [PMID: 28652416 DOI: 10.21873/invivo.11090] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Revised: 04/14/2017] [Accepted: 04/19/2017] [Indexed: 12/12/2022]
Abstract
Inherited optic neuropathies are a genetically diverse group of disorders mainly characterized by visual loss and optic atrophy. Since the first recognition of Leber's hereditary optic neuropathy, several genetic defects altering primary mitochondrial respiration have been proposed to contribute to the development of syndromic and non-syndromic optic neuropathies. Moreover, the genomics and imaging revolution in the past decade has increased diagnostic efficiency and accuracy, allowing recognition of a link between mitochondrial dynamics machinery and a broad range of inherited neurodegenerative diseases involving the optic nerve. Mutations of novel genes modifying mainly the balance between mitochondrial fusion and fission have been shown to lead to overlapping clinical phenotypes ranging from isolated optic atrophy to severe, sometimes lethal multisystem disorders, and are reviewed herein. Given the particular vulnerability of retinal ganglion cells to mitochondrial dysfunction, the accessibility of the eye as a part of the central nervous system and improvements in technical imaging concerning assessment of the retinal nerve fiber layer, optic nerve evaluation becomes critical - even in asymptomatic patients - for correct diagnosis, understanding and early treatment of these complex and enigmatic clinical entities.
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Affiliation(s)
- Eleni Bagli
- Institute of Molecular Biology and Biotechnology-FORTH, Division of Biomedical Research, Ioannina, Greece.,Department of Ophthalmology, University of Ioannina, Ioannina, Greece
| | - Anastasia K Zikou
- Department of Clinical Radiology, University of Ioannina, Ioannina, Greece
| | - Niki Agnantis
- Department of Pathology, University of Ioannina, Ioannina, Greece
| | - Georgios Kitsos
- Department of Ophthalmology, University of Ioannina, Ioannina, Greece
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14
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Hayashi T, Sasano H, Katagiri S, Tsunoda K, Kameya S, Nakazawa M, Iwata T, Tsuneoka H. Heterozygous deletion of the OPA1 gene in patients with dominant optic atrophy. Jpn J Ophthalmol 2017; 61:395-401. [DOI: 10.1007/s10384-017-0522-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2016] [Accepted: 05/09/2017] [Indexed: 11/30/2022]
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15
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Liskova P, Tesarova M, Dudakova L, Svecova S, Kolarova H, Honzik T, Seto S, Votruba M. OPA1 analysis in an international series of probands with bilateral optic atrophy. Acta Ophthalmol 2017; 95:363-369. [PMID: 27860320 DOI: 10.1111/aos.13285] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2016] [Accepted: 09/02/2016] [Indexed: 01/16/2023]
Abstract
PURPOSE To determine the molecular genetic cause in previously unreported probands with optic atrophy from the United Kingdom, Czech Republic and Canada. METHODS OPA1 coding regions and flanking intronic sequences were screened by direct sequencing in 82 probands referred with a diagnosis of bilateral optic atrophy. Detected rare variants were assessed for pathogenicity by in silico analysis. Segregation of the identified variants was performed in available first degree relatives. RESULTS A total of 29 heterozygous mutations evaluated as pathogenic were identified in 42 probands, of these seven were novel. In two probands, only variants of unknown significance were found. 76% of pathogenic mutations observed in 30 (71%) of 42 probands were evaluated to lead to unstable transcripts resulting in haploinsufficiency. Three probands with the following disease-causing mutations c.1230+1G>A, c.1367G>A and c.2965dup were documented to suffer from hearing loss and/or neurological impairment. CONCLUSIONS OPA1 gene screening in patients with bilateral optic atrophy is an important part of clinical evaluation as it may establish correct clinical diagnosis. Our study expands the spectrum of OPA1 mutations causing dominant optic atrophy and supports the fact that haploinsufficiency is the most common disease mechanism.
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Affiliation(s)
- Petra Liskova
- Institute of Inherited Metabolic Disorders; First Faculty of Medicine; Charles University and General University Hospital in Prague; Prague Czech Republic
- Department of Ophthalmology; First Faculty of Medicine; Charles University and General University Hospital in Prague; Prague Czech Republic
| | - Marketa Tesarova
- Department of Paediatrics and Adolescent Medicine; First Faculty of Medicine; Charles University and General University Hospital in Prague; Prague Czech Republic
| | - Lubica Dudakova
- Institute of Inherited Metabolic Disorders; First Faculty of Medicine; Charles University and General University Hospital in Prague; Prague Czech Republic
| | - Stepanka Svecova
- Department of Paediatrics and Adolescent Medicine; First Faculty of Medicine; Charles University and General University Hospital in Prague; Prague Czech Republic
| | - Hana Kolarova
- Department of Paediatrics and Adolescent Medicine; First Faculty of Medicine; Charles University and General University Hospital in Prague; Prague Czech Republic
| | - Tomas Honzik
- Department of Paediatrics and Adolescent Medicine; First Faculty of Medicine; Charles University and General University Hospital in Prague; Prague Czech Republic
| | - Sharon Seto
- Cardiff Eye Unit; University Hospital of Wales; Cardiff UK
- School of Optometry & Vision Sciences; Cardiff University; Cardiff UK
| | - Marcela Votruba
- Cardiff Eye Unit; University Hospital of Wales; Cardiff UK
- School of Optometry & Vision Sciences; Cardiff University; Cardiff UK
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16
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A neurodegenerative perspective on mitochondrial optic neuropathies. Acta Neuropathol 2016; 132:789-806. [PMID: 27696015 PMCID: PMC5106504 DOI: 10.1007/s00401-016-1625-2] [Citation(s) in RCA: 117] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2016] [Revised: 09/24/2016] [Accepted: 09/25/2016] [Indexed: 12/15/2022]
Abstract
Mitochondrial optic neuropathies constitute an important cause of chronic visual morbidity and registrable blindness in both the paediatric and adult population. It is a genetically heterogeneous group of disorders caused by both mitochondrial DNA (mtDNA) mutations and a growing list of nuclear genetic defects that invariably affect a critical component of the mitochondrial machinery. The two classical paradigms are Leber hereditary optic neuropathy (LHON), which is a primary mtDNA disorder, and autosomal dominant optic atrophy (DOA) secondary to pathogenic mutations within the nuclear gene OPA1 that encodes for a mitochondrial inner membrane protein. The defining neuropathological feature is the preferential loss of retinal ganglion cells (RGCs) within the inner retina but, rather strikingly, the smaller calibre RGCs that constitute the papillomacular bundle are particularly vulnerable, whereas melanopsin-containing RGCs are relatively spared. Although the majority of patients with LHON and DOA will present with isolated optic nerve involvement, some individuals will also develop additional neurological complications pointing towards a greater vulnerability of the central nervous system (CNS) in susceptible mutation carriers. These so-called “plus” phenotypes are mechanistically important as they put the loss of RGCs within the broader perspective of neuronal loss and mitochondrial dysfunction, highlighting common pathways that could be modulated to halt progressive neurodegeneration in other related CNS disorders. The management of patients with mitochondrial optic neuropathies still remains largely supportive, but the development of effective disease-modifying treatments is now within tantalising reach helped by major advances in drug discovery and delivery, and targeted genetic manipulation.
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17
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Sen NE, Drost J, Gispert S, Torres-Odio S, Damrath E, Klinkenberg M, Hamzeiy H, Akdal G, Güllüoğlu H, Başak AN, Auburger G. Search for SCA2 blood RNA biomarkers highlights Ataxin-2 as strong modifier of the mitochondrial factor PINK1 levels. Neurobiol Dis 2016; 96:115-126. [PMID: 27597528 DOI: 10.1016/j.nbd.2016.09.002] [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] [Received: 07/21/2016] [Revised: 08/24/2016] [Accepted: 09/01/2016] [Indexed: 12/13/2022] Open
Abstract
Ataxin-2 (ATXN2) polyglutamine domain expansions of large size result in an autosomal dominantly inherited multi-system-atrophy of the nervous system named spinocerebellar ataxia type 2 (SCA2), while expansions of intermediate size act as polygenic risk factors for motor neuron disease (ALS and FTLD) and perhaps also for Levodopa-responsive Parkinson's disease (PD). In view of the established role of ATXN2 for RNA processing in periods of cell stress and the expression of ATXN2 in blood cells such as platelets, we investigated whether global deep RNA sequencing of whole blood from SCA2 patients identifies a molecular profile which might serve as diagnostic biomarker. The bioinformatic analysis of SCA2 blood global transcriptomics revealed various significant effects on RNA processing pathways, as well as the pathways of Huntington's disease and PD where mitochondrial dysfunction is crucial. Notably, an induction of PINK1 and PARK7 expression was observed. Conversely, expression of Pink1 was severely decreased upon global transcriptome profiling of Atxn2-knockout mouse cerebellum and liver, in parallel to strong effects on Opa1 and Ghitm, which encode known mitochondrial dynamics regulators. These results were validated by quantitative PCR and immunoblots. Starvation stress of human SH-SY5Y neuroblastoma cells led to a transcriptional phasic induction of ATXN2 in parallel to PINK1, and the knockdown of one enhanced the expression of the other during stress response. These findings suggest that ATXN2 may modify the known PINK1 roles for mitochondrial quality control and autophagy during cell stress. Given that PINK1 is responsible for autosomal recessive juvenile PD, this genetic interaction provides a concept how the degeneration of nigrostriatal dopaminergic neurons and the Parkinson phenotype may be triggered by ATXN2 mutations.
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Affiliation(s)
- Nesli Ece Sen
- Experimental Neurology, Goethe University Medical School, 60590 Frankfurt/Main, Germany; Suna and İnan Kıraç Foundation, Neurodegeneration Research Laboratory (NDAL), Boğaziçi University, 34342 Istanbul, Turkey
| | - Jessica Drost
- Experimental Neurology, Goethe University Medical School, 60590 Frankfurt/Main, Germany
| | - Suzana Gispert
- Experimental Neurology, Goethe University Medical School, 60590 Frankfurt/Main, Germany
| | - Sylvia Torres-Odio
- Experimental Neurology, Goethe University Medical School, 60590 Frankfurt/Main, Germany
| | - Ewa Damrath
- Experimental Neurology, Goethe University Medical School, 60590 Frankfurt/Main, Germany
| | - Michael Klinkenberg
- Experimental Neurology, Goethe University Medical School, 60590 Frankfurt/Main, Germany
| | - Hamid Hamzeiy
- Suna and İnan Kıraç Foundation, Neurodegeneration Research Laboratory (NDAL), Boğaziçi University, 34342 Istanbul, Turkey
| | - Gülden Akdal
- Department of Neurology, Faculty of Medicine, Dokuz Eylül University, Izmir, Turkey
| | - Halil Güllüoğlu
- Department of Neurology, Faculty of Medicine, Izmir University, Izmir, Turkey
| | - A Nazlı Başak
- Suna and İnan Kıraç Foundation, Neurodegeneration Research Laboratory (NDAL), Boğaziçi University, 34342 Istanbul, Turkey.
| | - Georg Auburger
- Experimental Neurology, Goethe University Medical School, 60590 Frankfurt/Main, Germany.
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18
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Allen KF, Gaier ED, Wiggs JL. Genetics of Primary Inherited Disorders of the Optic Nerve: Clinical Applications. Cold Spring Harb Perspect Med 2015; 5:a017277. [PMID: 26134840 DOI: 10.1101/cshperspect.a017277] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Inherited disorders of the optic nerve significantly impact vision in children and adults. The optic nerve disorders most commonly encountered clinically are glaucoma and primary optic neuropathy including Leber's hereditary optic neuropathy (LHON) and autosomal dominant or Kjer's optic atrophy. Current knowledge of the genetics of optic neuropathy and glaucoma makes it possible to test for mutations in disease-causing genes allowing for presymptomatic testing and risk assessment, and recent advances have revealed important disease mechanisms that may suggest potential therapeutic targets. In this perspective, we describe the current approaches and limitations to genetic testing for these disorders and provide an update on the development of gene-based therapies.
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Affiliation(s)
- Keri F Allen
- Harvard Medical School, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts 02114
| | - Eric D Gaier
- Harvard Medical School, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts 02114
| | - Janey L Wiggs
- Harvard Medical School, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts 02114
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19
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Castori M, Bottillo I, Laino L, Morlino S, Grammatico B, Grammatico P. An additional patient with 3q27.3 microdeletion syndrome. J Child Neurol 2015; 30:500-4. [PMID: 25038125 DOI: 10.1177/0883073814539557] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/05/2014] [Accepted: 05/15/2014] [Indexed: 12/17/2022]
Abstract
The 3q27.3 microdeletion syndrome has been recently delineated in 7 subjects from 5 families sharing a 1.4 Mb smallest region of overlap. This condition appears recognizable by the association of Marfanoid habitus, mild but distinctive facial dysmorphism, intellectual disability, psychosis, and mood disorder. Here, we describe an additional 17-year-old man with an ~7.7-Mb deletion encompassing the 3q27.3 microdeletion critical region, previously run undetected at standard karyotyping. The constellation of major clinical findings overlaps with those reported in the 7 previously published patients and thus confirms the existence of a strongly recognizable syndrome linked to imbalance of 3q27.3. The role of AHSG and, possibly, of other genes in determining the 3q27.3 microdeletion habitus is discussed by comparison of the deleted segments. The involvement of adjacent loci and genes, such as OPA1 and GP5, may contribute in this patient to novel satellite features, such as optic atrophy and subclinical coagulopathy.
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Affiliation(s)
- Marco Castori
- Division of Medical Genetics, Department of Molecular Medicine, Sapienza University, San Camillo-Forlanini Hospital, Rome, Italy
| | - Irene Bottillo
- Division of Medical Genetics, Department of Molecular Medicine, Sapienza University, San Camillo-Forlanini Hospital, Rome, Italy
| | - Luigi Laino
- Division of Medical Genetics, Department of Molecular Medicine, Sapienza University, San Camillo-Forlanini Hospital, Rome, Italy
| | - Silvia Morlino
- Division of Medical Genetics, Department of Molecular Medicine, Sapienza University, San Camillo-Forlanini Hospital, Rome, Italy
| | - Barbara Grammatico
- Division of Medical Genetics, Department of Molecular Medicine, Sapienza University, San Camillo-Forlanini Hospital, Rome, Italy
| | - Paola Grammatico
- Division of Medical Genetics, Department of Molecular Medicine, Sapienza University, San Camillo-Forlanini Hospital, Rome, Italy
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20
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Abstract
Beyond their contribution to basic metabolism, the major cellular organelles, in particular mitochondria, can determine whether cells respond to stress in an adaptive or suicidal manner. Thus, mitochondria can continuously adapt their shape to changing bioenergetic demands as they are subjected to quality control by autophagy, or they can undergo a lethal permeabilization process that initiates apoptosis. Along similar lines, multiple proteins involved in metabolic circuitries, including oxidative phosphorylation and transport of metabolites across membranes, may participate in the regulated or catastrophic dismantling of organelles. Many factors that were initially characterized as cell death regulators are now known to physically or functionally interact with metabolic enzymes. Thus, several metabolic cues regulate the propensity of cells to activate self-destructive programs, in part by acting on nutrient sensors. This suggests the existence of "metabolic checkpoints" that dictate cell fate in response to metabolic fluctuations. Here, we discuss recent insights into the intersection between metabolism and cell death regulation that have major implications for the comprehension and manipulation of unwarranted cell loss.
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Affiliation(s)
- Douglas R Green
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA.
| | - Lorenzo Galluzzi
- Equipe 11 labellisée par la Ligue Nationale contre le Cancer, Centre de Recherche des Cordeliers, F-75006 Paris, France. Université Paris Descartes/Paris V; Sorbonne Paris Cité; F-75005 Paris, France. INSERM, U1138, F-94805 Villejuif, France
| | - Guido Kroemer
- Equipe 11 labellisée par la Ligue Nationale contre le Cancer, Centre de Recherche des Cordeliers, F-75006 Paris, France. Université Paris Descartes/Paris V; Sorbonne Paris Cité; F-75005 Paris, France. INSERM, U1138, F-94805 Villejuif, France. Metabolomics and Cell Biology Platforms, Gustave Roussy, F-94805 Villejuif, France. Pôle de Biologie, Hôpital Européen Georges Pompidou, Assistance Publique-Hôpitaux de Paris, F-75015 Paris, France.
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Sutherland JE, Day MA. Advantages and disadvantages of molecular testing in ophthalmology. EXPERT REVIEW OF OPHTHALMOLOGY 2014. [DOI: 10.1586/eop.11.2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Alavi MV, Fuhrmann N. Dominant optic atrophy, OPA1, and mitochondrial quality control: understanding mitochondrial network dynamics. Mol Neurodegener 2013; 8:32. [PMID: 24067127 PMCID: PMC3856479 DOI: 10.1186/1750-1326-8-32] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2013] [Accepted: 09/16/2013] [Indexed: 12/13/2022] Open
Abstract
Mitochondrial quality control is fundamental to all neurodegenerative diseases, including the most prominent ones, Alzheimer’s Disease and Parkinsonism. It is accomplished by mitochondrial network dynamics – continuous fission and fusion of mitochondria. Mitochondrial fission is facilitated by DRP1, while MFN1 and MFN2 on the mitochondrial outer membrane and OPA1 on the mitochondrial inner membrane are essential for mitochondrial fusion. Mitochondrial network dynamics are regulated in highly sophisticated ways by various different posttranslational modifications, such as phosphorylation, ubiquitination, and proteolytic processing of their key-proteins. By this, mitochondria process a wide range of different intracellular and extracellular parameters in order to adapt mitochondrial function to actual energetic and metabolic demands of the host cell, attenuate mitochondrial damage, recycle dysfunctional mitochondria via the mitochondrial autophagy pathway, or arrange for the recycling of the complete host cell by apoptosis. Most of the genes coding for proteins involved in this process have been associated with neurodegenerative diseases. Mutations in one of these genes are associated with a neurodegenerative disease that originally was described to affect retinal ganglion cells only. Since more and more evidence shows that other cell types are affected as well, we would like to discuss the pathology of dominant optic atrophy, which is caused by heterozygous sequence variants in OPA1, in the light of the current view on OPA1 protein function in mitochondrial quality control, in particular on its function in mitochondrial fusion and cytochrome C release. We think OPA1 is a good example to understand the molecular basis for mitochondrial network dynamics.
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Affiliation(s)
- Marcel V Alavi
- Department of Ophthalmology, University of California, San Francisco, 10 Koret Way, 94143-0730 San Francisco, CA, USA.
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SDOCT thickness measurements of various retinal layers in patients with autosomal dominant optic atrophy due to OPA1 mutations. BIOMED RESEARCH INTERNATIONAL 2013; 2013:121398. [PMID: 24024178 PMCID: PMC3760180 DOI: 10.1155/2013/121398] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/08/2013] [Revised: 07/16/2013] [Accepted: 07/19/2013] [Indexed: 12/27/2022]
Abstract
Purpose. To specify thickness values of various retinal layers on macular spectral domain Optical Coherence Tomography (SDOCT) scans in patients with autosomal dominant optic atrophy (ADOA) compared to healthy controls. Methods. SDOCT volume scans of 7 patients with ADOA (OPA-1 mutation) and 14 healthy controls were quantitatively analyzed using manual grading software. Mean thickness values for the ETDRS grid subfields 5–8 were calculated for the spaces neurosensory retina, retinal nerve fiber layer (RNFL), ganglion cell layer (GCL), a combined space of inner plexiform layer/outer plexiform layer/inner nuclear layer (IPL+INL+OPL), and a combined space of outer nuclear layer/photoreceptor layers (ONL+PL). Results. ADOA patients showed statistically significant lower retinal thickness values than controls (P < 0.01). RNFL (P < 0.001) and GCL thicknesses (P < 0.001) were significantly lower in ADOA patients. There was no difference in IPL+INL+OPL and in ONL+PL thickness. Conclusion. Manual subanalysis of macular SDOCT volume scans allowed detailed subanalysis of various retinal layers. Not only RNFL but also GCL thicknesses are reduced in the macular area of ADOA patients whereas subjacent layers are not involved. Together with clinical findings, macular SDOCT helps to identify patients with suspicion for hereditary optic neuropathy before genetic analysis confirms the diagnosis.
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Lenaers G, Hamel C, Delettre C, Amati-Bonneau P, Procaccio V, Bonneau D, Reynier P, Milea D. Dominant optic atrophy. Orphanet J Rare Dis 2012; 7:46. [PMID: 22776096 PMCID: PMC3526509 DOI: 10.1186/1750-1172-7-46] [Citation(s) in RCA: 171] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2011] [Accepted: 03/15/2012] [Indexed: 11/18/2022] Open
Abstract
Definition of the disease Dominant Optic Atrophy (DOA) is a neuro-ophthalmic condition characterized by a bilateral degeneration of the optic nerves, causing insidious visual loss, typically starting during the first decade of life. The disease affects primary the retinal ganglion cells (RGC) and their axons forming the optic nerve, which transfer the visual information from the photoreceptors to the lateral geniculus in the brain. Epidemiology The prevalence of the disease varies from 1/10000 in Denmark due to a founder effect, to 1/30000 in the rest of the world. Clinical description DOA patients usually suffer of moderate visual loss, associated with central or paracentral visual field deficits and color vision defects. The severity of the disease is highly variable, the visual acuity ranging from normal to legal blindness. The ophthalmic examination discloses on fundoscopy isolated optic disc pallor or atrophy, related to the RGC death. About 20% of DOA patients harbour extraocular multi-systemic features, including neurosensory hearing loss, or less commonly chronic progressive external ophthalmoplegia, myopathy, peripheral neuropathy, multiple sclerosis-like illness, spastic paraplegia or cataracts. Aetiology Two genes (OPA1, OPA3) encoding inner mitochondrial membrane proteins and three loci (OPA4, OPA5, OPA8) are currently known for DOA. Additional loci and genes (OPA2, OPA6 and OPA7) are responsible for X-linked or recessive optic atrophy. All OPA genes yet identified encode mitochondrial proteins embedded in the inner membrane and ubiquitously expressed, as are the proteins mutated in the Leber Hereditary Optic Neuropathy. OPA1 mutations affect mitochondrial fusion, energy metabolism, control of apoptosis, calcium clearance and maintenance of mitochondrial genome integrity. OPA3 mutations only affect the energy metabolism and the control of apoptosis. Diagnosis Patients are usually diagnosed during their early childhood, because of bilateral, mild, otherwise unexplained visual loss related to optic discs pallor or atrophy, and typically occurring in the context of a family history of DOA. Optical Coherence Tomography further discloses non-specific thinning of retinal nerve fiber layer, but a normal morphology of the photoreceptors layers. Abnormal visual evoked potentials and pattern ERG may also reflect the dysfunction of the RGCs and their axons. Molecular diagnosis is provided by the identification of a mutation in the OPA1 gene (75% of DOA patients) or in the OPA3 gene (1% of patients). Prognosis Visual loss in DOA may progress during puberty until adulthood, with very slow subsequent chronic progression in most of the cases. On the opposite, in DOA patients with associated extra-ocular features, the visual loss may be more severe over time. Management To date, there is no preventative or curative treatment in DOA; severely visually impaired patients may benefit from low vision aids. Genetic counseling is commonly offered and patients are advised to avoid alcohol and tobacco consumption, as well as the use of medications that may interfere with mitochondrial metabolism. Gene and pharmacological therapies for DOA are currently under investigation.
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Affiliation(s)
- Guy Lenaers
- Institut des Neurosciences de Montpellier, U1051 de l'INSERM, Université de Montpellier I et II, BP 74103, F-34091 Montpellier cedex 05, France.
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Mitochondrial dysfunction in glaucoma: Understanding genetic influences. Mitochondrion 2012; 12:202-12. [DOI: 10.1016/j.mito.2011.11.004] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2011] [Accepted: 11/11/2011] [Indexed: 12/27/2022]
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Nguyen D, Alavi MV, Kim KY, Kang T, Scott RT, Noh YH, Lindsey JD, Wissinger B, Ellisman MH, Weinreb RN, Perkins GA, Ju WK. A new vicious cycle involving glutamate excitotoxicity, oxidative stress and mitochondrial dynamics. Cell Death Dis 2011; 2:e240. [PMID: 22158479 PMCID: PMC3252734 DOI: 10.1038/cddis.2011.117] [Citation(s) in RCA: 152] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Glutamate excitotoxicity leads to fragmented mitochondria in neurodegenerative diseases, mediated by nitric oxide and S-nitrosylation of dynamin-related protein 1, a mitochondrial outer membrane fission protein. Optic atrophy gene 1 (OPA1) is an inner membrane protein important for mitochondrial fusion. Autosomal dominant optic atrophy (ADOA), caused by mutations in OPA1, is a neurodegenerative disease affecting mainly retinal ganglion cells (RGCs). Here, we showed that OPA1 deficiency in an ADOA model influences N-methyl-D-aspartate (NMDA) receptor expression, which is involved in glutamate excitotoxicity and oxidative stress. Opa1(enu/+) mice show a slow progressive loss of RGCs, activation of astroglia and microglia, and pronounced mitochondrial fission in optic nerve heads as found by electron tomography. Expression of NMDA receptors (NR1, 2A, and 2B) in the retina of Opa1(enu/+) mice was significantly increased as determined by western blot and immunohistochemistry. Superoxide dismutase 2 (SOD2) expression was significantly decreased, the apoptotic pathway was activated as Bax was increased, and phosphorylated Bad and BcL-xL were decreased. Our results conclusively demonstrate that not only glutamate excitotoxicity and/or oxidative stress alters mitochondrial fission/fusion, but that an imbalance in mitochondrial fission/fusion in turn leads to NMDA receptor upregulation and oxidative stress. Therefore, we propose a new vicious cycle involved in neurodegeneration that includes glutamate excitotoxicity, oxidative stress, and mitochondrial dynamics.
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Affiliation(s)
- D Nguyen
- The Sophie and Arthur Brody Laboratory for Optic Nerve Biology, Hamilton Glaucoma Center, Department of Ophthalmology, University of California San Diego, La Jolla, CA, USA
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Gallus GN, Cardaioli E, Rufa A, Collura M, Da Pozzo P, Pretegiani E, Tumino M, Pavone L, Federico A. High frequency of OPA1 mutations causing high ADOA prevalence in south-eastern Sicily, Italy. Clin Genet 2011; 82:277-82. [DOI: 10.1111/j.1399-0004.2011.01751.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Almind GJ, Grønskov K, Milea D, Larsen M, Brøndum-Nielsen K, Ek J. Genomic deletions in OPA1 in Danish patients with autosomal dominant optic atrophy. BMC MEDICAL GENETICS 2011; 12:49. [PMID: 21457585 PMCID: PMC3079616 DOI: 10.1186/1471-2350-12-49] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/03/2010] [Accepted: 04/04/2011] [Indexed: 05/26/2023]
Abstract
Background Autosomal dominant optic atrophy (ADOA, Kjer disease, MIM #165500) is the most common form of hereditary optic neuropathy. Mutations in OPA1 located at chromosome 3q28 are the predominant cause for ADOA explaining between 32 and 89% of cases. Although deletions of OPA1 were recently reported in ADOA, the frequency of OPA1 genomic rearrangements in Denmark, where ADOA has a high prevalence, is unknown. The aim of the study was to identify copy number variations in OPA1 in Danish ADOA patients. Methods Forty unrelated ADOA patients, selected from a group of 100 ADOA patients as being negative for OPA1 point mutations, were tested for genomic rearrangements in OPA1 by multiplex ligation probe amplification (MLPA). When only one probe was abnormal results were confirmed by additional manually added probes. Segregation analysis was performed in families with detected mutations when possible. Results Ten families had OPA1 deletions, including two with deletions of the entire coding region and eight with intragenic deletions. Segregation analysis was possible in five families, and showed that the deletions segregated with the disease. Conclusion Deletions in the OPA1 gene were found in 10 patients presenting with phenotypic autosomal dominant optic neuropathy. Genetic testing for deletions in OPA1 should be offered for patients with clinically diagnosed ADOA and no OPA1 mutations detected by DNA sequencing analysis.
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Affiliation(s)
- Gitte J Almind
- Center for Applied Human Molecular Genetics, The Kennedy Center, Glostrup, Denmark.
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Yu-Wai-Man P, Griffiths PG, Chinnery PF. Mitochondrial optic neuropathies - disease mechanisms and therapeutic strategies. Prog Retin Eye Res 2011; 30:81-114. [PMID: 21112411 PMCID: PMC3081075 DOI: 10.1016/j.preteyeres.2010.11.002] [Citation(s) in RCA: 431] [Impact Index Per Article: 33.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Leber hereditary optic neuropathy (LHON) and autosomal-dominant optic atrophy (DOA) are the two most common inherited optic neuropathies in the general population. Both disorders share striking pathological similarities, marked by the selective loss of retinal ganglion cells (RGCs) and the early involvement of the papillomacular bundle. Three mitochondrial DNA (mtDNA) point mutations; m.3460G>A, m.11778G>A, and m.14484T>C account for over 90% of LHON cases, and in DOA, the majority of affected families harbour mutations in the OPA1 gene, which codes for a mitochondrial inner membrane protein. Optic nerve degeneration in LHON and DOA is therefore due to disturbed mitochondrial function and a predominantly complex I respiratory chain defect has been identified using both in vitro and in vivo biochemical assays. However, the trigger for RGC loss is much more complex than a simple bioenergetic crisis and other important disease mechanisms have emerged relating to mitochondrial network dynamics, mtDNA maintenance, axonal transport, and the involvement of the cytoskeleton in maintaining a differential mitochondrial gradient at sites such as the lamina cribosa. The downstream consequences of these mitochondrial disturbances are likely to be influenced by the local cellular milieu. The vulnerability of RGCs in LHON and DOA could derive not only from tissue-specific, genetically-determined biological factors, but also from an increased susceptibility to exogenous influences such as light exposure, smoking, and pharmacological agents with putative mitochondrial toxic effects. Our concept of inherited mitochondrial optic neuropathies has evolved over the past decade, with the observation that patients with LHON and DOA can manifest a much broader phenotypic spectrum than pure optic nerve involvement. Interestingly, these phenotypes are sometimes clinically indistinguishable from other neurodegenerative disorders such as Charcot-Marie-Tooth disease, hereditary spastic paraplegia, and multiple sclerosis, where mitochondrial dysfunction is also thought to be an important pathophysiological player. A number of vertebrate and invertebrate disease models has recently been established to circumvent the lack of human tissues, and these have already provided considerable insight by allowing direct RGC experimentation. The ultimate goal is to translate these research advances into clinical practice and new treatment strategies are currently being investigated to improve the visual prognosis for patients with mitochondrial optic neuropathies.
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MESH Headings
- Animals
- DNA, Mitochondrial/genetics
- Disease Models, Animal
- Humans
- Optic Atrophy, Autosomal Dominant/pathology
- Optic Atrophy, Autosomal Dominant/physiopathology
- Optic Atrophy, Autosomal Dominant/therapy
- Optic Atrophy, Hereditary, Leber/pathology
- Optic Atrophy, Hereditary, Leber/physiopathology
- Optic Atrophy, Hereditary, Leber/therapy
- Optic Nerve/pathology
- Phenotype
- Point Mutation
- Retinal Ganglion Cells/pathology
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Affiliation(s)
- Patrick Yu-Wai-Man
- Mitochondrial Research Group, Institute for Ageing and Health, The Medical School, Newcastle University, UK.
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Carelli V, Schimpf S, Fuhrmann N, Valentino ML, Zanna C, Iommarini L, Papke M, Schaich S, Tippmann S, Baumann B, Barboni P, Longanesi L, Rugolo M, Ghelli A, Alavi MV, Youle RJ, Bucchi L, Carroccia R, Giannoccaro MP, Tonon C, Lodi R, Cenacchi G, Montagna P, Liguori R, Wissinger B. A clinically complex form of dominant optic atrophy (OPA8) maps on chromosome 16. Hum Mol Genet 2011; 20:1893-905. [PMID: 21349918 DOI: 10.1093/hmg/ddr071] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Dominant optic atrophy (DOA) is genetically heterogeneous and pathogenic mutations have been identified in the OPA1 and OPA3 genes, both encoding for mitochondrial proteins. We characterized clinical and laboratory features in a large OPA1-negative family with complicated DOA. Search for mitochondrial dysfunction was performed by studying muscle biopsies, fibroblasts, platelets and magnetic resonance (MR) spectroscopy. Genetic investigations included mitochondrial DNA (mtDNA) analysis, linkage analysis, copy number variation (CNV) analysis and candidate gene screening. Optic neuropathy was undistinguishable from that in OPA1-DOA and frequently associated with late-onset sensorineural hearing loss, increases of central conduction times at somato-sensory evoked potentials and various cardiac abnormalities. Serum lactic acid after exercise, platelet respiratory complex activities, adenosine triphosphate (ATP) content in fibroblasts and muscle phosphorus MR spectroscopy all failed to reveal a mitochondrial dysfunction. However, muscle biopsies and their mtDNA analysis showed increased mitochondrial biogenesis. Furthermore, patient's fibroblasts grown in the galactose medium were unable to increase ATP content compared with controls, and exhibited abnormally high rate of fusion activity. Genome-wide linkage revealed a locus on chromosome 16q21-q22 with a maximum two-point LOD score of 8.84 for the marker D16S752 and a non-recombinant interval of ∼ 6.96 cM. Genomic screening of 45 genes in this interval including several likely candidate genes (CALB2, CYB5B, TK2, DHODH, PLEKHG4) revealed no mutation. Moreover, we excluded the presence of CNVs using array-based comparative genome hybridization. The identification of a new OPA locus (OPA8) in this pedigree demonstrates further genetic heterogeneity in DOA, and our results indicate that the pathogenesis may still involve mitochondria.
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Affiliation(s)
- Valerio Carelli
- Department of Neurological Sciences, University of Bologna, Via Ugo Foscolo 7, 40123 Bologna, Italy.
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Genetic screening for OPA1 and OPA3 mutations in patients with suspected inherited optic neuropathies. Ophthalmology 2010; 118:558-63. [PMID: 21036400 DOI: 10.1016/j.ophtha.2010.07.029] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2010] [Revised: 06/11/2010] [Accepted: 07/29/2010] [Indexed: 10/18/2022] Open
Abstract
PURPOSE Autosomal-dominant optic atrophy (DOA) is one of the most common inherited optic neuropathies, and it is genetically heterogeneous, with mutations in both OPA1 and OPA3 known to cause disease. Approximately 60% of cases harbor OPA1 mutations, whereas OPA3 mutations have been reported in only 2 pedigrees with DOA and premature cataracts. The aim of this study was to determine the yield of OPA1 and OPA3 screening in a cohort of presumed DOA cases referred to a tertiary diagnostic laboratory. DESIGN Retrospective case series. PARTICIPANTS One hundred eighty-eight probands with bilateral optic atrophy referred for molecular genetic investigations at a tertiary diagnostic facility: 38 patients with an autosomal-dominant pattern of inheritance and 150 sporadic cases. METHODS OPA1 and OPA3 genetic testing was initially performed using polymerase chain reaction-based sequencing methods. The presence of large-scale OPA1 and OPA3 genomic rearrangements was assessed further with a targeted comparative genomic hybridization microarray platform. The 3 primary Leber hereditary optic neuropathy (LHON) mutations, m.3460G→>A, m.11778G→A, and m.14484T→C, also were screened in all patients. MAIN OUTCOME MEASURES The proportion of patients with OPA1 and OPA3 pathogenic mutations. The clinical profile observed in molecularly confirmed DOA cases. RESULTS Twenty-one different OPA1 mutations were found in 27 (14.4%) of the 188 probands screened. The mutations included 6 novel pathogenic variants and the first reported OPA1 initiation codon mutation at c.1A→T. An OPA1 missense mutation, c.239A→G (p.Y80C), was identified in an 11-year-old black girl with optic atrophy and peripheral sensorimotor neuropathy in her lower limbs. The OPA1 detection rate was significantly higher among individuals with a positive family history of visual failure (50.0%) compared with sporadic cases (5.3%). The primary LHON screen was negative in the patient cohort, and additional molecular investigations did not reveal any large-scale OPA1 rearrangements or OPA3 genetic defects. The mean baseline visual acuity for the OPA1-positive group was 0.48 logarithm of the minimum angle of resolution (units mean Snellen equivalent, 20/61; range, 20/20-20/400; 95% confidence interval, 20/52-20/71), and visual deterioration occurred in 54.2% of patients during follow-up. CONCLUSIONS OPA1 mutations are the most common genetic defects identified in patients with suspected DOA, whereas OPA3 mutations are very rare in isolated optic atrophy cases.
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Fuhrmann N, Schimpf S, Kamenisch Y, Leo-Kottler B, Alexander C, Auburger G, Zrenner E, Wissinger B, Alavi MV. Solving a 50 year mystery of a missing OPA1 mutation: more insights from the first family diagnosed with autosomal dominant optic atrophy. Mol Neurodegener 2010; 5:25. [PMID: 20546606 PMCID: PMC2893178 DOI: 10.1186/1750-1326-5-25] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2009] [Accepted: 06/14/2010] [Indexed: 12/16/2022] Open
Abstract
Background Up to the 1950s, there was an ongoing debate about the diversity of hereditary optic neuropathies, in particular as to whether all inherited optic atrophies can be ascribed to Leber's hereditary optic neuropathy (LHON) or represent different disease entities. In 1954 W. Jaeger published a detailed clinical and genealogical investigation of a large family with explicit autosomal dominant segregation of optic atrophy thus proving the existence of a discrete disease different from LHON, which is nowadays known as autosomal dominant optic atrophy (ADOA). Since the year 2000 ADOA is associated with genomic mutations in the OPA1 gene, which codes for a protein that is imported into mitochondria where it is required for mitochondrial fusion. Interestingly enough, the underlying mutation in this family has not been identified since then. Results We have reinvestigated this family with the aim to identify the mutation and to further clarify the underlying pathomechanism. Patients showed a classical non-syndromic ADOA. The long term deterioration in vision in the two teenagers examined 50 years later is of particular note 5/20 to 6/120. Multiplex ligation probe amplification revealed a duplication of the OPA1 exons 7-9 which was confirmed by long distance PCR and cDNA analysis, resulting in an in-frame duplication of 102 amino acids. Segregation was verified in 53 available members of the updated pedigree and a penetrance of 88% was calculated. Fibroblast cultures from skin biopsies were established to assess the mitochondrial network integrity and to qualitatively and quantitatively study the consequences of the mutation on transcript and protein level. Fibroblast cultures demonstrated a fragmented mitochondrial network. Processing of the OPA1 protein was altered. There was no correlation of the OPA1 transcript levels and the OPA1 protein levels in the fibroblasts. Intriguingly an overall decrease of mitochondrial proteins was observed in patients' fibroblasts, while the OPA1 transcript levels were elevated. Conclusions The thorough study of this family provides a detailed clinical picture accompanied by a molecular investigation of patients' fibroblasts. Our data show a classic OPA1-associated non-syndromic ADOA segregating in this family. Cell biological findings suggest that OPA1 is regulated by post-translational mechanisms and we would like to hypothesize that loss of OPA1 function might lead to impaired mitochondrial quality control. With the clinical, genetic and cell biological characterisation of a family described already more than 50 years ago, we span more than half a century of research in optic neuropathies.
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Affiliation(s)
- Nico Fuhrmann
- Molecular Genetics Laboratory, Institute for Ophthalmic Research, Centre for Ophthalmology, University of Tuebingen, Germany.
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The prevalence and natural history of dominant optic atrophy due to OPA1 mutations. Ophthalmology 2010; 117:1538-46, 1546.e1. [PMID: 20417570 DOI: 10.1016/j.ophtha.2009.12.038] [Citation(s) in RCA: 128] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2009] [Revised: 12/17/2009] [Accepted: 12/22/2009] [Indexed: 11/22/2022] Open
Abstract
PURPOSE Autosomal dominant optic atrophy (DOA) is a major cause of visual impairment in young adults that is characterized by selective retinal ganglion cell loss. To define the prevalence and natural history of this optic nerve disorder, we performed a population-based epidemiologic and molecular study of presumed DOA cases in the north of England. DESIGN Case series. PARTICIPANTS Seventy-six affected probands with a clinical diagnosis of DOA were identified from our neuro-ophthalmology and neurogenetics database. METHODS OPA1 genetic testing was performed using a polymerase chain reaction-based sequencing strategy. OPA1-negative cases were then screened for large-scale OPA1 rearrangements and OPA3 mutations. Additional affected family members identified through contact tracing were examined, and longitudinal visual data were analyzed. MAIN OUTCOME MEASURES The prevalence and molecular characteristics of DOA in the north of England. Visual function and disease progression among patients with OPA1-positive mutations. RESULTS The detection rate of OPA1 mutations was 57.6% among probands with a positive family history of optic atrophy (19/33) and 14.0% among singleton cases (6/43). Approximately two thirds of our families with DOA harbored OPA1 mutations (14/22, 63.6%), and 5 novel OPA1 mutations were identified. Only 1 family carried a large-scale OPA1 rearrangement, and no OPA3 mutations were found in our optic atrophy cohort. The minimum point prevalence of DOA in the north of England was 2.87 per 100,000 (95% confidence interval [CI], 2.54-3.20), or 2.09 per 100,000 (95% CI, 1.95-2.23) when only OPA1-positive cases were considered. Snellen visual acuity varied markedly between OPA1-positive cases with a mean of 20/173 (range 20/20 to hand movements), and visual function worsened in 67.4% of patients during follow-up. The mean rate of visual loss was 0.032 logarithm of the minimum angle of resolution per year, but some patients experienced faster visual decline (range = 0-0.171 logarithm of the minimum angle of resolution/year). OPA1 missense mutations were associated with a significantly worse visual outcome compared with other mutational subtypes (P=0.0001). CONCLUSIONS Dominant optic atrophy causes significant visual morbidity and affects at least 1 in 35,000 of the general population.
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Walter MC, Czermin B, Muller-Ziermann S, Bulst S, Stewart JD, Hudson G, Schneiderat P, Abicht A, Holinski-Feder E, Lochmüller H, Chinnery PF, Klopstock T, Horvath R. Late-onset ptosis and myopathy in a patient with a heterozygous insertion in POLG2. J Neurol 2010; 257:1517-23. [DOI: 10.1007/s00415-010-5565-9] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2010] [Revised: 03/12/2010] [Accepted: 03/30/2010] [Indexed: 10/19/2022]
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Alavi MV, Fuhrmann N, Nguyen HP, Yu-Wai-Man P, Heiduschka P, Chinnery PF, Wissinger B. Subtle neurological and metabolic abnormalities in an Opa1 mouse model of autosomal dominant optic atrophy. Exp Neurol 2009; 220:404-9. [DOI: 10.1016/j.expneurol.2009.09.026] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2009] [Revised: 09/09/2009] [Accepted: 09/28/2009] [Indexed: 12/20/2022]
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Amati-Bonneau P, Milea D, Bonneau D, Chevrollier A, Ferré M, Guillet V, Gueguen N, Loiseau D, Crescenzo MAPD, Verny C, Procaccio V, Lenaers G, Reynier P. OPA1-associated disorders: Phenotypes and pathophysiology. Int J Biochem Cell Biol 2009; 41:1855-65. [DOI: 10.1016/j.biocel.2009.04.012] [Citation(s) in RCA: 93] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2008] [Revised: 04/09/2009] [Accepted: 04/14/2009] [Indexed: 10/20/2022]
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