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Pasol J, Uddin MS, Tekin M, Moore HP. Leber Hereditary Optic Neuropathy in 2 Sisters With Friedreich Ataxia. J Neuroophthalmol 2024:00041327-990000000-00606. [PMID: 38564284 DOI: 10.1097/wno.0000000000002143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Affiliation(s)
- Joshua Pasol
- Bascom Palmer Eye Institute (JP), University of Miami Miller School of Medicine, Plantation, FL; Palmetto General Hospital (MSU); and Departments of Clinical and Translational Genetics (MT) and Neurology (HPM), University of Miami Miller School of Medicine, Miami, FL
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2
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Sanchis-Juan A, Megy K, Stephens J, Armirola Ricaurte C, Dewhurst E, Low K, French CE, Grozeva D, Stirrups K, Erwood M, McTague A, Penkett CJ, Shamardina O, Tuna S, Daugherty LC, Gleadall N, Duarte ST, Hedrera-Fernández A, Vogt J, Ambegaonkar G, Chitre M, Josifova D, Kurian MA, Parker A, Rankin J, Reid E, Wakeling E, Wassmer E, Woods CG, Raymond FL, Carss KJ. Genome sequencing and comprehensive rare-variant analysis of 465 families with neurodevelopmental disorders. Am J Hum Genet 2023; 110:1343-1355. [PMID: 37541188 PMCID: PMC10432178 DOI: 10.1016/j.ajhg.2023.07.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2023] [Revised: 07/07/2023] [Accepted: 07/07/2023] [Indexed: 08/06/2023] Open
Abstract
Despite significant progress in unraveling the genetic causes of neurodevelopmental disorders (NDDs), a substantial proportion of individuals with NDDs remain without a genetic diagnosis after microarray and/or exome sequencing. Here, we aimed to assess the power of short-read genome sequencing (GS), complemented with long-read GS, to identify causal variants in participants with NDD from the National Institute for Health and Care Research (NIHR) BioResource project. Short-read GS was conducted on 692 individuals (489 affected and 203 unaffected relatives) from 465 families. Additionally, long-read GS was performed on five affected individuals who had structural variants (SVs) in technically challenging regions, had complex SVs, or required distal variant phasing. Causal variants were identified in 36% of affected individuals (177/489), and a further 23% (112/489) had a variant of uncertain significance after multiple rounds of re-analysis. Among all reported variants, 88% (333/380) were coding nuclear SNVs or insertions and deletions (indels), and the remainder were SVs, non-coding variants, and mitochondrial variants. Furthermore, long-read GS facilitated the resolution of challenging SVs and invalidated variants of difficult interpretation from short-read GS. This study demonstrates the value of short-read GS, complemented with long-read GS, in investigating the genetic causes of NDDs. GS provides a comprehensive and unbiased method of identifying all types of variants throughout the nuclear and mitochondrial genomes in individuals with NDD.
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Affiliation(s)
- Alba Sanchis-Juan
- Department of Haematology, University of Cambridge, Cambridge, UK; NIHR BioResource, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK; Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA; Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, USA; Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Karyn Megy
- Department of Haematology, University of Cambridge, Cambridge, UK; NIHR BioResource, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK; Centre for Genomics Research, Discovery Sciences, BioPharmaceuticals R&D, AstraZeneca, Cambridge, UK
| | - Jonathan Stephens
- Department of Haematology, University of Cambridge, Cambridge, UK; NIHR BioResource, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK
| | - Camila Armirola Ricaurte
- Department of Haematology, University of Cambridge, Cambridge, UK; NIHR BioResource, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK
| | - Eleanor Dewhurst
- Department of Haematology, University of Cambridge, Cambridge, UK; NIHR BioResource, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK
| | - Kayyi Low
- Department of Haematology, University of Cambridge, Cambridge, UK; NIHR BioResource, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK
| | | | - Detelina Grozeva
- Department of Medical Genetics, University of Cambridge, Cambridge, UK; Centre for Trials Research, Cardiff University, Cardiff, UK
| | - Kathleen Stirrups
- Department of Haematology, University of Cambridge, Cambridge, UK; NIHR BioResource, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK
| | - Marie Erwood
- Department of Haematology, University of Cambridge, Cambridge, UK; NIHR BioResource, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK
| | - Amy McTague
- Molecular Neurosciences, Zayed Centre for Research into Rare Disease in Children, UCL Great Ormond Street Institute of Child Health, London, UK; Department of Neurology, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
| | - Christopher J Penkett
- Department of Haematology, University of Cambridge, Cambridge, UK; NIHR BioResource, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK
| | - Olga Shamardina
- Department of Haematology, University of Cambridge, Cambridge, UK; NIHR BioResource, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK
| | - Salih Tuna
- Department of Haematology, University of Cambridge, Cambridge, UK; NIHR BioResource, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK
| | - Louise C Daugherty
- Department of Haematology, University of Cambridge, Cambridge, UK; NIHR BioResource, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK
| | - Nicholas Gleadall
- Department of Haematology, University of Cambridge, Cambridge, UK; NIHR BioResource, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK
| | - Sofia T Duarte
- Hospital Dona Estefânia, Centro Hospitalar de Lisboa Central, Lisbon, Portugal
| | | | - Julie Vogt
- West Midlands Regional Genetics Service, Birmingham Women's and Children's Hospital, Birmingham, UK
| | - Gautam Ambegaonkar
- Child Development Centre, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK
| | - Manali Chitre
- Clinical Medical School, University of Cambridge, Cambridge, UK
| | | | - Manju A Kurian
- Molecular Neurosciences, Zayed Centre for Research into Rare Disease in Children, UCL Great Ormond Street Institute of Child Health, London, UK
| | - Alasdair Parker
- Clinical Medical School, University of Cambridge, Cambridge, UK; Child Development Centre, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK
| | - Julia Rankin
- Department of Clinical Genetics, Royal Devon University Healthcare NHS Foundation Trust, Exeter, UK
| | - Evan Reid
- Cambridge Institute for Medical Research and Department of Medical Genetics, University of Cambridge, Cambridge, UK
| | - Emma Wakeling
- North West Thames Regional Genetics Service, Harrow, UK
| | - Evangeline Wassmer
- Neurology Department, Birmingham Women and Children's Hospital, Birmingham, UK
| | - C Geoffrey Woods
- Clinical Medical School, University of Cambridge, Cambridge, UK; Department of Medical Genetics, University of Cambridge, Cambridge, UK
| | - F Lucy Raymond
- Department of Haematology, University of Cambridge, Cambridge, UK; NIHR BioResource, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK; Department of Medical Genetics, University of Cambridge, Cambridge, UK.
| | - Keren J Carss
- Department of Haematology, University of Cambridge, Cambridge, UK; NIHR BioResource, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK; Centre for Genomics Research, Discovery Sciences, BioPharmaceuticals R&D, AstraZeneca, Cambridge, UK.
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3
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Tagliani S, Malaventura C, Ceccato C, Parmeggiani F, Suppiej A. Leber Mitochondrial Optic Neuropathy in Pediatric Females With Focus on Very Early Onset Cases. J Child Neurol 2023; 38:5-15. [PMID: 36659874 DOI: 10.1177/08830738221149962] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The aim of this study was to describe the phenotype of Leber hereditary optic neuropathy occurring in pediatric females. This disease generally affects young adult males, but it can occur also in females, and research data in this population is lacking. The very early onset can challenge the diagnosis and delay treatment. We searched PubMed through February 2021 and identified 226 pediatric females with genetically confirmed Leber hereditary optic neuropathy and added a new case of a 3-year-old female. The male-female ratio was 1.8:1; the mean onset age in females was 11 years with the onset at 3 years of age occurring in 3 females only. Acute onset with mild visual impairment was the most common presentation, associated with optic disc edema in 16%. Differential diagnoses are pseudotumor cerebri, optic nerve drusen and optic neuritis. The outcome is poor with partial recovery in 50%, despite some receiving Idebenone therapy.
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Affiliation(s)
- Sara Tagliani
- Department of Medical Sciences, Pediatric Section, University Hospital of Ferrara, Ferrara, Italy
| | - Cristina Malaventura
- Department of Medical Sciences, Pediatric Section, University Hospital of Ferrara, Ferrara, Italy
| | | | - Francesco Parmeggiani
- Department of Translational Medicine and for Romagna, 9299University of Ferrara, Ferrara, Italy.,ERN-EYE Network - Center for Retinitis Pigmentosa of Veneto Region, 196013Camposampiero Hospital, Padova, Italy
| | - Agnese Suppiej
- Department of Medical Sciences, Pediatric Section, University Hospital of Ferrara, Ferrara, Italy.,87812Robert Hollman Foundation, Padova, Italy.,ERN-EYE Network - Center for Retinitis Pigmentosa of Veneto Region, 196013Camposampiero Hospital, Padova, Italy
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4
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Lopriore P, Ricciarini V, Siciliano G, Mancuso M, Montano V. Mitochondrial Ataxias: Molecular Classification and Clinical Heterogeneity. Neurol Int 2022; 14:337-356. [PMID: 35466209 PMCID: PMC9036286 DOI: 10.3390/neurolint14020028] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Revised: 03/26/2022] [Accepted: 03/28/2022] [Indexed: 01/25/2023] Open
Abstract
Ataxia is increasingly being recognized as a cardinal manifestation in primary mitochondrial diseases (PMDs) in both paediatric and adult patients. It can be caused by disruption of cerebellar nuclei or fibres, its connection with the brainstem, or spinal and peripheral lesions leading to proprioceptive loss. Despite mitochondrial ataxias having no specific defining features, they should be included in hereditary ataxias differential diagnosis, given the high prevalence of PMDs. This review focuses on the clinical and neuropathological features and genetic background of PMDs in which ataxia is a prominent manifestation.
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Zeviani M, Carelli V. Mitochondrial Retinopathies. Int J Mol Sci 2021; 23:210. [PMID: 35008635 PMCID: PMC8745158 DOI: 10.3390/ijms23010210] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Revised: 12/14/2021] [Accepted: 12/18/2021] [Indexed: 12/13/2022] Open
Abstract
The retina is an exquisite target for defects of oxidative phosphorylation (OXPHOS) associated with mitochondrial impairment. Retinal involvement occurs in two ways, retinal dystrophy (retinitis pigmentosa) and subacute or chronic optic atrophy, which are the most common clinical entities. Both can present as isolated or virtually exclusive conditions, or as part of more complex, frequently multisystem syndromes. In most cases, mutations of mtDNA have been found in association with mitochondrial retinopathy. The main genetic abnormalities of mtDNA include mutations associated with neurogenic muscle weakness, ataxia and retinitis pigmentosa (NARP) sometimes with earlier onset and increased severity (maternally inherited Leigh syndrome, MILS), single large-scale deletions determining Kearns-Sayre syndrome (KSS, of which retinal dystrophy is a cardinal symptom), and mutations, particularly in mtDNA-encoded ND genes, associated with Leber hereditary optic neuropathy (LHON). However, mutations in nuclear genes can also cause mitochondrial retinopathy, including autosomal recessive phenocopies of LHON, and slowly progressive optic atrophy caused by dominant or, more rarely, recessive, mutations in the fusion/mitochondrial shaping protein OPA1, encoded by a nuclear gene on chromosome 3q29.
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Affiliation(s)
- Massimo Zeviani
- Department of Neurosciences, The Clinical School, University of Padova, 35128 Padova, Italy
- Veneto Institute of Molecular Medicine, Via Orus 2, 35128 Padova, Italy
| | - Valerio Carelli
- Department of Biomedical and Neuromotor Sciences, University of Bologna, 40139 Bologna, Italy
- Programma di Neurogenetica, IRCCS Istituto delle Scienze Neurologiche di Bologna, Via Altura 6, 40139 Bologna, Italy
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6
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Bursle C, Riney K, Stringer J, Moore D, Gole G, Kearns LS, Mackey DA, Coman D. Leber Hereditary Optic Neuropathy and Longitudinally Extensive Transverse Myelitis. JIMD Rep 2017; 42:53-60. [PMID: 29249004 PMCID: PMC6226398 DOI: 10.1007/8904_2017_79] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Revised: 11/02/2017] [Accepted: 11/27/2017] [Indexed: 12/23/2022] Open
Abstract
Leber Hereditary Optic Neuropathy is an inherited optic neuropathy caused by mitochondrial DNA point mutations leading to sudden, painless loss of vision. We report a case of an 8-year-old boy presenting with a radiological phenotype of longitudinally extensive transverse myelitis on a background of severe visual impairment secondary to Leber Hereditary Optic Neuropathy (LHON). He was found to have dual mitochondrial DNA mutations at 14484 (MTND6 gene) and 4160 (MTND1 gene) in a family with a severe form of LHON characterised by not only an unusually high penetrance of optic neuropathy, but also severe extra-ocular neurological complications. The m.14484T>C mutation is a common LHON mutation, but the m.4160T>C mutation is to our knowledge not reported outside this family and appears to drive the neurological manifestations. To our knowledge there have been no previous reports of spinal cord lesions in children with LHON.
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Affiliation(s)
- C Bursle
- Neurosciences Unit, The Lady Cilento Children's Hospital, Brisbane, QLD, Australia
- School of Medicine, The University of Queensland, Brisbane, QLD, Australia
| | - K Riney
- Neurosciences Unit, The Lady Cilento Children's Hospital, Brisbane, QLD, Australia
- School of Medicine, The University of Queensland, Brisbane, QLD, Australia
| | - J Stringer
- Neurosciences Unit, The Lady Cilento Children's Hospital, Brisbane, QLD, Australia
| | - D Moore
- Department of Paediatrics, The Wesley Hospital, Brisbane, QLD, Australia
| | - G Gole
- Department of Ophthalmology, The Lady Cilento Children's Hospital, Brisbane, QLD, Australia
| | - L S Kearns
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, East Melbourne, VIC, Australia
- Ophthalmology, Department of Surgery, University of Melbourne, Parkville, VIC, Australia
| | - D A Mackey
- Lions Eye Institute, Centre for Ophthalmology and Visual Science, University of Western Australia, Perth, WA, Australia
- School of Medicine, Menzies Institute for Medical Research, University of Tasmania, Hobart, TAS, Australia
| | - D Coman
- Neurosciences Unit, The Lady Cilento Children's Hospital, Brisbane, QLD, Australia.
- UnitingCare Clinical School, The Wesley Hospital, Brisbane, QLD, Australia.
- School of Medicine, The University of Queensland, Brisbane, QLD, Australia.
- Department of Paediatrics, The Wesley Hospital, Brisbane, QLD, Australia.
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7
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Beh SC, Frohman TC, Frohman EM. Neuro-ophthalmic Manifestations of Cerebellar Disease. Neurol Clin 2014; 32:1009-80. [DOI: 10.1016/j.ncl.2014.07.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Shin C Beh
- Department of Neurology, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390, USA
| | - Teresa C Frohman
- Department of Neurology, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390, USA
| | - Elliot M Frohman
- Department of Neurology, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390, USA; Department of Ophthalmology, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390, USA.
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Badura-Stronka M, Wawrocka A, Zawieja K, Silska S, Krawczyński MR. Severe manifestation of Leber's hereditary optic neuropathy due to 11778G>A mtDNA mutation in a female with hypoestrogenism due to Perrault syndrome. Mitochondrion 2013; 13:831-4. [PMID: 23748049 DOI: 10.1016/j.mito.2013.05.011] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2012] [Revised: 05/07/2013] [Accepted: 05/21/2013] [Indexed: 12/14/2022]
Abstract
Perrault syndrome (PS) is a rare autosomal recessive condition with ovarian dysgenesis, hearing deficit and neurological abnormalities in female patients. The molecular basis of the syndrome is heterogeneous, mutations in the HSD17B4 gene have been identified in one family and mutations in the HARS2 gene have been found in another one. We have excluded pathogenic changes in the HSD17B4 gene and in the HARS2 gene by a direct sequencing of all coding exons in a female with clinical hallmarks of PS, ataxia and mild mental retardation. In addition, the patient suffers from severe Leber's hereditary optic neuropathy (LHON) due to 11778G>A mtDNA mutation. This case is the first reported patient with PS and LHON. Possible influence of hypoestrogenism on the manifestation of optic neuropathy in this patient is discussed in the context of recent findings concerning the crucial role of estrogens in supporting the vision capacity in LHON-related mtDNA mutation carriers.
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Affiliation(s)
- Magdalena Badura-Stronka
- Chair and Department of Medical Genetics, Poznan University of Medical Sciences, Poznań, Poland; Center for Medical Genetics GENESIS, Poznań, Poland.
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Nakaso K, Adachi Y, Fusayasu E, Doi K, Imamura K, Yasui K, Nakashima K. Leber's Hereditary Optic Neuropathy with Olivocerebellar Degeneration due to G11778A and T3394C Mutations in the Mitochondrial DNA. J Clin Neurol 2012; 8:230-4. [PMID: 23091534 PMCID: PMC3469805 DOI: 10.3988/jcn.2012.8.3.230] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2011] [Revised: 10/21/2011] [Accepted: 10/21/2011] [Indexed: 11/30/2022] Open
Abstract
Background Leber's hereditary optic neuropathy (LHON) is a mitochondrial disorder with optic nerve atrophy. Although there are no other associated neurological abnormalities in most cases of LHON, cases of "LHON plus" have been reported. Case Report The proband was a 37-year-old man who had visual and gait disturbances that had first appeared at 10 years of age. He showed horizontal gaze palsy, gaze-evoked nystagmus, dysarthria, and cerebellar ataxia. Brain and orbit MRI disclosed atrophy of the optic nerve and cerebellum, and degenerative changes in the bilateral inferior olivary nucleus. Mutational analyses of mitochondrial DNA identified the coexistence of heteroplasmic G11778A and homoplasmic T3394C mutations. Conclusions These results suggest that the combination of G11778A and T3394C mutations leads to an atypical LHON phenotype.
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Affiliation(s)
- Kazuhiro Nakaso
- Division of Neurology, Department of Brain and Neurosciences, Faculty of Medicine, Tottori University, Yonago, Japan
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Karbowski M, Neutzner A. Neurodegeneration as a consequence of failed mitochondrial maintenance. Acta Neuropathol 2012; 123:157-71. [PMID: 22143516 DOI: 10.1007/s00401-011-0921-0] [Citation(s) in RCA: 137] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2011] [Revised: 11/18/2011] [Accepted: 11/22/2011] [Indexed: 02/06/2023]
Abstract
Maintaining the functional integrity of mitochondria is pivotal for cellular survival. It appears that neuronal homeostasis depends on high-fidelity mitochondria, in particular. Consequently, mitochondrial dysfunction is a fundamental problem associated with a significant number of neurological diseases, including Parkinson's disease (PD), Huntington's disease (HD), Alzheimer's disease (AD), amyotrophic lateral sclerosis (ALS) and various peripheral neuropathies, as well as the normal aging process. To ensure optimal mitochondrial function, diverse, evolutionarily conserved mitochondrial quality control mechanisms are in place, including the scavenging of toxic reactive oxygen species (ROS) and degradation of damaged mitochondrial proteins, but also turnover of whole organelles. In this review we will discuss various mitochondria-associated conditions, focusing on the role of protein turnover in mitochondrial maintenance with special emphasis on neurodegenerative disorders.
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Affiliation(s)
- Mariusz Karbowski
- Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
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11
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Kirches E. LHON: Mitochondrial Mutations and More. Curr Genomics 2011; 12:44-54. [PMID: 21886454 PMCID: PMC3129042 DOI: 10.2174/138920211794520150] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2010] [Revised: 12/14/2010] [Accepted: 12/28/2010] [Indexed: 11/22/2022] Open
Abstract
Leber’s hereditary optic neuropathy (LHON) is a mitochondrial disorder leading to severe visual impairment or even blindness by death of retinal ganglion cells (RGCs). The primary cause of the disease is usually a mutation of the mitochondrial genome (mtDNA) causing a single amino acid exchange in one of the mtDNA-encoded subunits of NADH:ubiquinone oxidoreductase, the first complex of the electron transport chain. It was thus obvious to accuse neuronal energy depletion as the most probable mediator of neuronal death. The group of Valerio Carelli and other authors have nicely shown that energy depletion shapes the cell fate in a LHON cybrid cell model. However, the cybrids used were osteosarcoma cells, which do not fully model neuronal energy metabolism. Although complex I mutations may cause oxidative stress, a potential pathogenetic role of the latter was less taken into focus. The hypothesis of bioenergetic failure does not provide a simple explanation for the relatively late disease onset and for the incomplete penetrance, which differs remarkably between genders. It is assumed that other genetic and environmental factors are needed in addition to the ‘primary LHON mutations’ to elicit RGC death. Relevant nuclear modifier genes have not been identified so far. The review discusses the unresolved problems of a pathogenetic hypothesis based on ATP decline and/or ROS-induced apoptosis in RGCs.
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Affiliation(s)
- E Kirches
- Department of Neuropathology, Otto-von-Guericke University, Leipziger Str. 44, 39120 Magdeburg, Germany
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Leber's Hereditary Optic Neuropathy-Gene Therapy: From Benchtop to Bedside. J Ophthalmol 2010; 2011:179412. [PMID: 21253496 PMCID: PMC3021870 DOI: 10.1155/2011/179412] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2010] [Revised: 10/07/2010] [Accepted: 11/12/2010] [Indexed: 02/06/2023] Open
Abstract
Leber's hereditary optic neuropathy (LHON) is a maternally transmitted disorder caused by point mutations in mitochondrial DNA (mtDNA). Most cases are due to mutations in genes encoding subunits of the NADH-ubiquinone oxidoreductase that is Complex I of the electron transport chain (ETC). These mutations are located at nucleotide positions 3460, 11778, or 14484 in the mitochondrial genome. The disease is characterized by apoplectic, bilateral, and severe visual loss. While the mutated mtDNA impairs generation of ATP by all mitochondria, there is only a selective loss of retinal ganglion cells and degeneration of optic nerve axons. Thus, blindness is typically permanent. Half of the men and 10% of females who harbor the pathogenic mtDNA mutation actually develop the phenotype. This incomplete penetrance and gender bias is not fully understood. Additional mitochondrial and/or nuclear genetic factors may modulate the phenotypic expression of LHON. In a population-based study, the mtDNA background of haplogroup J was associated with an inverse relationship of low-ATP generation and increased production of reactive oxygen species (ROS). Effective therapy for LHON has been elusive. In this paper, we describe the findings of pertinent published studies and discuss the controversies of potential strategies to ameliorate the disease.
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Tońska K, Kodroń A, Bartnik E. Genotype-phenotype correlations in Leber hereditary optic neuropathy. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2010; 1797:1119-23. [PMID: 20211598 DOI: 10.1016/j.bbabio.2010.02.032] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2009] [Revised: 01/29/2010] [Accepted: 02/26/2010] [Indexed: 01/09/2023]
Abstract
Leber hereditary optic neuropathy (LHON), acute or subacute vision loss due to retinal ganglion cell death which in the long run leads to optic nerve atrophy is one of the most widely studied maternally inherited diseases caused by mutations in mitochondrial DNA. Although three common mutations, 11778G>A, 14484T>C or 3460G>A are responsible for over 90% of cases and affect genes encoding complex I subunits of the respiratory chain, their influence on bioenergetic properties of the cell is marginal and cannot fully explain the pathology of the disease. The following chain of events was proposed, based on biochemical and anatomical properties of retinal ganglion cells whose axons form the optic nerve: mitochondrial DNA mutations increase reactive oxygen species production in these sensitive cells, leading to caspase-independent apoptosis. As LHON is characterized by low penetrance and sex bias (men are affected about 5 times more frequently than women) the participation of the other factors-genetic and environmental-beside mtDNA mutations was studied. Mitochondrial haplogroups and smoking are some of the factors involved in the complex etiology of this disease.
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MESH Headings
- Apoptosis
- DNA, Mitochondrial/genetics
- Electron Transport Complex I/genetics
- Energy Metabolism
- Female
- Genetic Association Studies
- Humans
- Male
- Models, Biological
- Mutation, Missense
- Optic Atrophy, Hereditary, Leber/genetics
- Optic Atrophy, Hereditary, Leber/metabolism
- Optic Atrophy, Hereditary, Leber/pathology
- Optic Atrophy, Hereditary, Leber/therapy
- Optic Nerve/metabolism
- Optic Nerve/pathology
- Penetrance
- Reactive Oxygen Species/metabolism
- Sex Characteristics
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Affiliation(s)
- Katarzyna Tońska
- Institute of Genetics and Biotechnology, Faculty of Biology, University of Warsaw, Ul. Pawinskiego 5a, 02-106 Warsaw, Poland
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Abstract
Mitochondrial disorders (MIDs) are an increasingly recognized condition. The second most frequently affected organ in MIDs is the central nervous system. One of the most prevalent clinical CNS manifestations of MIDs is ataxia. Ataxia may be even the dominant manifestation of a MID. This is why certain MIDs should be included in the classification of heredoataxias or at least considered as differentials of classical heredoataxias. MIDs due to mutations of the mitochondrial DNA, which develop ataxia include the MERRF, NARP, MILS, or KSS syndrome. More rarely, ataxia may be a feature of MELAS, LHON, PS, MIDD, or MSL. MIDs due to mutations of the nuclear DNA, which develop ataxia include LS, SANDO, SCAE, AHS, XSLA/A, IOSCA, MIRAS, MEMSA, or LBSL syndrome. More rarely ataxia can be found in AD-CPEO, AR-CPEO, MNGIE, DIDMOAD, CoQ-deficiency, ADOAD, DCMA, or PDC-deficiency. MIDs most frequently associated with ataxia are the non-syndromic MIDs. Syndromic and non-syndromic MIDs with ataxia should be delineated from classical heredoataxias to initiate appropriate symptomatic or supportive treatment.
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Sales LV, Velasco TR, Funayama S, Ribeiro LT, Andrade-Valença LP, Neder L, Fernandes RMF, Araujo D, Machado HR, Santos AC, Leite JP. Relative frequency, clinical, neuroimaging, and postsurgical features of pediatric temporal lobe epilepsy. Braz J Med Biol Res 2006; 39:1365-72. [PMID: 16906314 DOI: 10.1590/s0100-879x2006001000013] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2005] [Accepted: 06/20/2006] [Indexed: 11/22/2022] Open
Abstract
We describe the relative frequency, clinical features, neuroimaging and pathological results, and outcome after pharmacological or surgical intervention for a series of pediatric patients with temporal lobe epilepsy (TLE) from an epilepsy center in Brazil. The medical records of children younger than 12 years with features strongly suggestive of TLE were reviewed from January 1999 to June 1999. Selected children were evaluated regarding clinical, EEG, and magnetic resonance imaging (MRI) investigation and divided into three groups according to MRI: group 1 (G1, N = 9), patients with hippocampal atrophy; group 2 (G2, N = 10), patients with normal MRI, and group 3 (G3, N = 12), patients with other specific temporal lesions. A review of 1732 records of children with epilepsy revealed 31 cases with TLE (relative frequency of 1.79%). However, when the investigation was narrowed to cases with intractable seizures that needed video-EEG monitoring (N = 68) or epilepsy surgery (N = 32), the relative frequency of TLE increased to 19.11 (13/68) and 31.25% (10/32), respectively. At the beginning of the study, 25 of 31 patients had a high seizure frequency (80.6%), which declined to 11 of 31 (35.5%) at the conclusion of the study, as a consequence of pharmacological and/or surgical therapy. This improvement in seizure control was significant in G1 (P < 0.05) and G3 (P < 0.01) mainly due to good postsurgical outcome, and was not significant in G2 (P > 0.1, McNemar's test). These results indicate that the relative frequency of TLE in children was low, but increased considerably among cases with pharmacoresistant seizures. Patients with specific lesions were likely to undergo surgery, with good postoperative outcomes.
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Affiliation(s)
- L V Sales
- Departamento de Neurologia, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Avenida Bandeirantes 3900, 14049-900 Ribeirão Preto, SP, Brazil
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Carelli V. Chapter 4 Leber's Hereditary Optic Neuropathy. MITOCHONDRIAL DISORDERS IN NEUROLOGY 2 2002. [DOI: 10.1016/s1877-3419(09)70063-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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Abstract
Rapid progress has been made in the identification of mitochondrial DNA mutations which are typically associated with diseases of the nervous system and muscle. The well established mitochondrial disorders are maternally inherited and males and females are equally affected. An exception is Leber's hereditary optic atrophy (LHON) which is observed much more frequently in males than in females. There are three common point mutations in LHON which can be homoplasmic or heteroplasmic. In mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS) most mutations are single base changes and lie within the tRNA-Leu gene. Point mutations in myoclonic epilepsy with ragged red fibres (MERRF) usually occur within the tRNA-Lys gene but mutations of the tRNA-Leu gene are also observed. MELAS and MERRF mutations are heteroplasmic and there is considerable clinical overlap between these diseases. Point mutations within the ATPase6 gene result in either neuropathy, ataxia and retinitis pigmentosa (NARP) or in Leigh's syndrome. The latter occurs if the mutation is present in the majority of mitochondria (extreme heteroplasmy). Finally, mitochondrial DNA deletions are the cause underlying Kearns-Sayre syndrome (KSS). Apart from the well-established mitochondrial diseases, there is increasing evidence that mitochondrial mutations may also play a role in the neurodegenerative disorders Parkinson, Alzheimer and Huntington disease. The complex I defect found in Parkinson disease is especially interesting in this respect. However, no causative mitochondrial mutation has as yet been established in any of these three common disorders.
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Affiliation(s)
- M B Graeber
- Department of Neuromorphology, Max-Planck-Institute of Psychiatry, Martinsried, Germany.
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