1
|
Sundaramurthy S, SelvaKumar A, Ching J, Dharani V, Sarangapani S, Yu-Wai-Man P. Leber hereditary optic neuropathy-new insights and old challenges. Graefes Arch Clin Exp Ophthalmol 2021; 259:2461-2472. [PMID: 33185731 DOI: 10.1007/s00417-020-04993-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Revised: 09/16/2020] [Accepted: 10/23/2020] [Indexed: 12/20/2022] Open
Abstract
Leber hereditary optic neuropathy (LHON) is the most common primary mitochondrial DNA (mtDNA) disorder with the majority of patients harboring one of three primary mtDNA point mutations, namely, m.3460G>A (MTND1), m.11778G>A (MTND4), and m.14484T>C (MTND6). LHON is characterized by bilateral subacute loss of vision due to the preferential loss of retinal ganglion cells (RGCs) within the inner retina, resulting in optic nerve degeneration. This review describes the clinical features associated with mtDNA LHON mutations and recent insights gained into the disease mechanisms contributing to RGC loss in this mitochondrial disorder. Although treatment options remain limited, LHON research has now entered an active translational phase with ongoing clinical trials, including gene therapy to correct the underlying pathogenic mtDNA mutation.
Collapse
Affiliation(s)
- Srilekha Sundaramurthy
- 1SN Oil and Natural Gas Corporation (ONGC) Department of Genetics & Molecular Biology, Vision Research Foundation, Chennai, India.
| | - Ambika SelvaKumar
- Department of Neuro-Ophthalmology, Medical Research Foundation, Chennai, India
| | - Jared Ching
- Cambridge Eye Unit, Addenbrooke's Hospital, Cambridge University Hospitals, Cambridge, UK
- John Van Geest Centre for Brain Repair and MRC Mitochondrial Biology Unit, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
| | - Vidhya Dharani
- Department of Neuro-Ophthalmology, Medical Research Foundation, Chennai, India
| | - Sripriya Sarangapani
- 1SN Oil and Natural Gas Corporation (ONGC) Department of Genetics & Molecular Biology, Vision Research Foundation, Chennai, India
| | - Patrick Yu-Wai-Man
- Cambridge Eye Unit, Addenbrooke's Hospital, Cambridge University Hospitals, Cambridge, UK
- John Van Geest Centre for Brain Repair and MRC Mitochondrial Biology Unit, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
- NIHR Biomedical Research Centre, Moorfields Eye Hospital and UCL Institute of Ophthalmology, London, UK
| |
Collapse
|
2
|
Yokota Y, Hara M, Akimoto T, Mizoguchi T, Goto YI, Nishino I, Kamei S, Nakajima H. Late-onset MELAS syndrome with mtDNA 14453G→A mutation masquerading as an acute encephalitis: a case report. BMC Neurol 2020; 20:247. [PMID: 32552696 PMCID: PMC7298965 DOI: 10.1186/s12883-020-01818-w] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Accepted: 06/03/2020] [Indexed: 02/06/2023] Open
Abstract
Background A unique patient with MELAS syndrome, who initially masqueraded as having acute encephalitis and was eventually diagnosed with MELAS syndrome harboring a mtDNA 14453G → A mutation, is described. Case presentation A 74-year-old Japanese man was admitted to another hospital due to acute onset of cognitive impairment and psychosis. After 7 days he was transferred to our hospital with seizures and deteriorating psychosis. The results of primary ancillary tests that included EEG, CSF findings, and brain MRI supported the diagnosis of an acute encephalitis. HSV-DNA and antibodies against neuronal surface antigens in the CSF were all negative. With the assistance of the lactate peak on the brain lesions in the magnetic resonance spectroscopy image and genetic analysis of the biopsied muscle, he was eventually diagnosed with MELAS syndrome harboring mtDNA 14453G → A mutation in the ND6 gene. Conclusions This case provides a caveat that MELAS syndrome can manifest in the symptoms and ancillary tests masquerading as an acute encephalitis caused by infection or autoimmunity. This is the first adult patient seen to harbor the mtDNA14453G → A with a unique onset, which broadens the phenotypic spectrum of MELAS syndrome associated with ND6 gene mutation.
Collapse
Affiliation(s)
- Yuki Yokota
- Division of Neurology, Department of Medicine, Nihon University School of Medicine, 30-1, Oyaguchi-Kamicyo, Itabashi-ku, Tokyo, 173-8610, Japan
| | - Makoto Hara
- Division of Neurology, Department of Medicine, Nihon University School of Medicine, 30-1, Oyaguchi-Kamicyo, Itabashi-ku, Tokyo, 173-8610, Japan.
| | - Takayoshi Akimoto
- Division of Neurology, Department of Medicine, Nihon University School of Medicine, 30-1, Oyaguchi-Kamicyo, Itabashi-ku, Tokyo, 173-8610, Japan
| | - Tomotaka Mizoguchi
- Division of Neurology, Department of Medicine, Nihon University School of Medicine, 30-1, Oyaguchi-Kamicyo, Itabashi-ku, Tokyo, 173-8610, Japan
| | - Yu-Ichi Goto
- Medical Genome Center, National Center of Neurology and Psychiatry, Tokyo, Japan.,Department of Mental Retardation and Birth Defect Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Ichizo Nishino
- Department of Neuromuscular Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Satoshi Kamei
- Division of Neurology, Department of Medicine, Nihon University School of Medicine, 30-1, Oyaguchi-Kamicyo, Itabashi-ku, Tokyo, 173-8610, Japan.,Center for Neuro-infection, Department of Neurology, Ageo Central General Hospital, Saitama, Japan
| | - Hideto Nakajima
- Division of Neurology, Department of Medicine, Nihon University School of Medicine, 30-1, Oyaguchi-Kamicyo, Itabashi-ku, Tokyo, 173-8610, Japan
| |
Collapse
|
3
|
Fiedorczuk K, Sazanov LA. Mammalian Mitochondrial Complex I Structure and Disease-Causing Mutations. Trends Cell Biol 2018; 28:835-867. [PMID: 30055843 DOI: 10.1016/j.tcb.2018.06.006] [Citation(s) in RCA: 98] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Revised: 06/14/2018] [Accepted: 06/22/2018] [Indexed: 12/31/2022]
Abstract
Complex I has an essential role in ATP production by coupling electron transfer from NADH to quinone with translocation of protons across the inner mitochondrial membrane. Isolated complex I deficiency is a frequent cause of mitochondrial inherited diseases. Complex I has also been implicated in cancer, ageing, and neurodegenerative conditions. Until recently, the understanding of complex I deficiency on the molecular level was limited due to the lack of high-resolution structures of the enzyme. However, due to developments in single particle cryo-electron microscopy (cryo-EM), recent studies have reported nearly atomic resolution maps and models of mitochondrial complex I. These structures significantly add to our understanding of complex I mechanism and assembly. The disease-causing mutations are discussed here in their structural context.
Collapse
Affiliation(s)
- Karol Fiedorczuk
- Institute of Science and Technology Austria, Am Campus 1, Klosterneuburg 3400, Austria; Present address: The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA
| | - Leonid A Sazanov
- Institute of Science and Technology Austria, Am Campus 1, Klosterneuburg 3400, Austria.
| |
Collapse
|
4
|
Finsterer J, Zarrouk-Mahjoub S. Striatal necrosis due to the m.14459G>A mutation. J Neurol Sci 2017; 380:281-282. [PMID: 28709590 DOI: 10.1016/j.jns.2017.07.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Accepted: 07/04/2017] [Indexed: 11/24/2022]
Affiliation(s)
| | - Sinda Zarrouk-Mahjoub
- University of Tunis El Manar and Genomics Platform, Pasteur Institute of Tunis, Tunisia
| |
Collapse
|
5
|
Rajakulendran S, Pitceathly RDS, Taanman JW, Costello H, Sweeney MG, Woodward CE, Jaunmuktane Z, Holton JL, Jacques TS, Harding BN, Fratter C, Hanna MG, Rahman S. A Clinical, Neuropathological and Genetic Study of Homozygous A467T POLG-Related Mitochondrial Disease. PLoS One 2016; 11:e0145500. [PMID: 26735972 PMCID: PMC4703200 DOI: 10.1371/journal.pone.0145500] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Accepted: 12/06/2015] [Indexed: 02/06/2023] Open
Abstract
Mutations in the nuclear gene POLG (encoding the catalytic subunit of DNA polymerase gamma) are an important cause of mitochondrial disease. The most common POLG mutation, A467T, appears to exhibit considerable phenotypic heterogeneity. The mechanism by which this single genetic defect results in such clinical diversity remains unclear. In this study we evaluate the clinical, neuropathological and mitochondrial genetic features of four unrelated patients with homozygous A467T mutations. One patient presented with the severe and lethal Alpers-Huttenlocher syndrome, which was confirmed on neuropathology, and was found to have a depletion of mitochondrial DNA (mtDNA). Of the remaining three patients, one presented with mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes (MELAS), one with a phenotype in the Myoclonic Epilepsy, Myopathy and Sensory Ataxia (MEMSA) spectrum and one with Sensory Ataxic Neuropathy, Dysarthria and Ophthalmoplegia (SANDO). All three had secondary accumulation of multiple mtDNA deletions. Complete sequence analysis of muscle mtDNA using the MitoChip resequencing chip in all four cases demonstrated significant variation in mtDNA, including a pathogenic MT-ND5 mutation in one patient. These data highlight the variable and overlapping clinical and neuropathological phenotypes and downstream molecular defects caused by the A467T mutation, which may result from factors such as the mtDNA genetic background, nuclear genetic modifiers and environmental stressors.
Collapse
Affiliation(s)
- Sanjeev Rajakulendran
- UCL Institute of Neurology and National Hospital for Neurology and Neurosurgery and the MRC Centre for Neuromuscular Diseases, Queen Square, London WC1N 3BG, United Kingdom
| | - Robert D. S. Pitceathly
- UCL Institute of Neurology and National Hospital for Neurology and Neurosurgery, Queen Square, London WC1N 3BG, United Kingdom and Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, King’s College London SE5 8AF, United Kingdom
| | - Jan-Willem Taanman
- Department of Clinical Neurosciences, UCL Institute of Neurology, London NW3 2PF, United Kingdom
| | - Harry Costello
- Mitochondrial Research Group, Genetics and Genomic Medicine, UCL Institute of Child Health, London WC1N 1EH, United Kingdom
| | - Mary G. Sweeney
- Department of Neurogenetics, UCL Institute of Neurology and National Hospital for Neurology, Queen Square, London WC1N 3BG, United Kingdom
| | - Cathy E. Woodward
- Department of Neurogenetics, UCL Institute of Neurology and National Hospital for Neurology, Queen Square, London WC1N 3BG, United Kingdom
| | - Zane Jaunmuktane
- Division of Neuropathology, UCL Institute of Neurology and National Hospital for Neurology, Queen Square, London WC1N 3BG, United Kingdom
| | - Janice L. Holton
- Division of Neuropathology, UCL Institute of Neurology and National Hospital for Neurology, Queen Square, London WC1N 3BG, United Kingdom
| | - Thomas S. Jacques
- Developmental Biology and Cancer Programme, UCL Institute of Child Health and Department of Histopathology, Great Ormond Street Hospital for Children Foundation Trust, London WC1N 1EH, United Kingdom
| | - Brian N. Harding
- Division of Neuropathology, The Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania, United States of America
| | - Carl Fratter
- Oxford Medical Genetics Laboratories, Oxford University Hospitals NHS Trust, Churchill Hospital, Oxford OX3 7LE, United Kingdom
| | - Michael G. Hanna
- UCL Institute of Neurology and National Hospital for Neurology and Neurosurgery and the MRC Centre for Neuromuscular Diseases, Queen Square, London WC1N 3BG, United Kingdom
| | - Shamima Rahman
- Mitochondrial Research Group, Genetics and Genomic Medicine, UCL Institute of Child Health, London WC1N 1EH, United Kingdom
- Metabolic Unit, Great Ormond Street Hospital, London WC1N 3JH, United Kingdom
- * E-mail:
| |
Collapse
|
6
|
Chen T, Liu Q, Jiang L, Liu C, Ou Q. Mitochondrial COX2 G7598A mutation may have a modifying role in the phenotypic manifestation of aminoglycoside antibiotic-induced deafness associated with 12S rRNA A1555G mutation in a Han Chinese pedigree. Genet Test Mol Biomarkers 2013; 17:122-30. [PMID: 23256547 PMCID: PMC3552164 DOI: 10.1089/gtmb.2012.0251] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Recent studies suggest that certain mitochondrial haplogroup markers and some specific variants in mitochondrial haplogroup may also influence the phenotypic expression of particular mitochondrial disorders. In this report, the clinical, genetic, and molecular characterization were identified in a Chinese pedigree with the aminoglycoside antibiotic (AmAn)-induced deafness and nonsyndromic hearing loss (NSHL). The pathogenic gene responsible for this hereditary NSHL pedigree was determined by Microarray chip, which possessed the nine NSHL hot-spot mutations, including GJB2 (35delG, 176dell6bp, 235de1C, and 299delAT), GJB3 (538C>T), SLC26A4 (IVS7-2A>G and 2168A>G), and mitochondrial DNA (mtDNA) 12S rRNA (C1494T and A1555G). Only the homoplasmic A1555G mutation was detected, which was confirmed by direct sequencing. Also, real-time amplification refractory mutation system quantitative polymerase chain reaction methodology was performed to calculate the A1555G mutation load. The proband's complete mtDNA genome were amplified and direct sequencing was performed to determine the mitochondrial haplogroup and private mutations. The proband's mitochondrial haplogroup belonges to M7b1 and a private mutation MTCOX2 G7598A (p.Ala 5 Thr) is found. Phylogenetic analysis of COX2 polypeptide sequences demonstrates that the alanine residue is relatively conserved, but owing to the missense mutation (p.Ala 5 Thr), its side chain hydrophobicity will be changed, and what is more, as it is adjacent to a glutamine residue, which is highly conserved and hydrophilic, in an evolutionary stable domain; G7598A (p.Ala 5 Thr) may alter the protein secondary structure and physiological function of COX2 and, thus, aggravate the mitochondrial dysfunction conferred by the A1555G mutation. Furthermore, the G7598A mutation is absent in 100 unrelated healthy controls; therefore, G7598A (p.Ala 5 Thr) in the mitochondrial haplogoup M7b1 may have a modifying role, enhancing its penetrance and severity, in the AmAn-induced deafness and NSHL associated with 12S rRNA A1555G mutation in the Han Chinese pedigree.
Collapse
Affiliation(s)
- Tianbin Chen
- First Clinical College, Fujian Medical University, Fuzhou, China
- Department of Laboratory Medicine, The First Affiliated Hospital of Fujian Medical University, Fuzhou, China
- The First Affiliated Hospital of Fujian Medical University Clinical Transformation Base of Biochip Beijing National Engineering Research Center, Fuzhou, China
| | - Qicai Liu
- Department of Laboratory Medicine, The First Affiliated Hospital of Fujian Medical University, Fuzhou, China
- The First Affiliated Hospital of Fujian Medical University Clinical Transformation Base of Biochip Beijing National Engineering Research Center, Fuzhou, China
| | - Ling Jiang
- Department of Laboratory Medicine, The First Affiliated Hospital of Fujian Medical University, Fuzhou, China
- The First Affiliated Hospital of Fujian Medical University Clinical Transformation Base of Biochip Beijing National Engineering Research Center, Fuzhou, China
| | - Can Liu
- Department of Laboratory Medicine, The First Affiliated Hospital of Fujian Medical University, Fuzhou, China
- The First Affiliated Hospital of Fujian Medical University Clinical Transformation Base of Biochip Beijing National Engineering Research Center, Fuzhou, China
| | - Qishui Ou
- Department of Laboratory Medicine, The First Affiliated Hospital of Fujian Medical University, Fuzhou, China
- The First Affiliated Hospital of Fujian Medical University Clinical Transformation Base of Biochip Beijing National Engineering Research Center, Fuzhou, China
| |
Collapse
|
7
|
Iommarini L, Calvaruso MA, Kurelac I, Gasparre G, Porcelli AM. Complex I impairment in mitochondrial diseases and cancer: Parallel roads leading to different outcomes. Int J Biochem Cell Biol 2013; 45:47-63. [DOI: 10.1016/j.biocel.2012.05.016] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2012] [Revised: 05/03/2012] [Accepted: 05/24/2012] [Indexed: 02/06/2023]
|
8
|
Induction of the permeability transition pore in cells depleted of mitochondrial DNA. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2012; 1817:1860-6. [PMID: 22402226 DOI: 10.1016/j.bbabio.2012.02.022] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2012] [Revised: 02/16/2012] [Accepted: 02/21/2012] [Indexed: 02/08/2023]
Abstract
Respiratory complexes are believed to play a role in the function of the mitochondrial permeability transition pore (PTP), whose dysregulation affects the process of cell death and is involved in a variety of diseases, including cancer and degenerative disorders. We investigated here the PTP in cells devoid of mitochondrial DNA (ρ(0) cells), which lack respiration and constitute a model for the analysis of mitochondrial involvement in several pathological conditions. We observed that mitochondria of ρ(0) cells maintain a membrane potential and that this is readily dissipated after displacement of hexokinase (HK) II from the mitochondrial surface by treatment with either the drug clotrimazole or with a cell-permeant HK II peptide, or by placing ρ(0) cells in a medium without serum and glucose. The PTP inhibitor cyclosporin A (CsA) could decrease the mitochondrial depolarization induced by either HK II displacement or by nutrient depletion. We also found that a fraction of the kinases ERK1/2 and GSK3α/β is located in the mitochondrial matrix of ρ(0) cells, and that glucose and serum deprivation caused concomitant ERK1/2 inhibition and GSK3α/β activation with the ensuing phosphorylation of cyclophilin D, the mitochondrial target of CsA. GSK3α/β inhibition with indirubin-3'-oxime decreased PTP-induced cell death in ρ(0) cells following nutrient ablation. These findings indicate that ρ(0) cells are equipped with a functioning PTP, whose regulatory mechanisms are similar to those observed in cancer cells, and suggest that escape from PTP opening is a survival factor in this model of mitochondrial diseases. This article is part of a Special Issue entitled: 17th European Bioenergetics Conference (EBEC 2012).
Collapse
|
9
|
Shidara K, Wakakura M. Leber's hereditary optic neuropathy with the 3434, 9011 mitochondrial DNA point mutation. Jpn J Ophthalmol 2011; 56:175-80. [PMID: 22183138 DOI: 10.1007/s10384-011-0106-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2010] [Accepted: 09/28/2011] [Indexed: 11/24/2022]
Abstract
BACKGROUND Leber's hereditary optic neuropathy (LHON) contains several well-known mitochondrial DNA (mtDNA) point mutations. We report a case with characteristic clinical manifestations of LHON involving a possible new LHON point mutation. CASE A 34-year-old man was diagnosed with LHON. The patient exhibited (1) sudden onset of bilateral visual loss, (2) normal light reflex, and (3) swelling of the peripapillary nerve fiber layer. After subsequent development of bilateral optic disc pallor, we concluded that the patient had LHON. mtDNA analysis was conducted using non-radioisotopic single-strand conformational polymorphism followed by direct sequencing. There was no change in the patient's visual acuity during the 26-month follow-up period. OBSERVATIONS The mtDNA point mutations were found at T3434C, G3483A, and V9011A. The confirmed mtDNA substitutions included (1) A-G at nucleotide position 3434, (2) G-A at nucleotide position 3483, and (3) C-T at nucleotide position 9011. The amino acid code at the nucleotide positions 3434 and 9011 was phylogenetically highly conserved. CONCLUSION The 3434 and 9011 mtDNA point mutations are candidates for a new LHON mutation.
Collapse
Affiliation(s)
- Kyoko Shidara
- Inouye Eye Hospital, 4-3 Kanda-Surugadai, Chiyoda-ku, Tokyo, 101-0062, Japan.
| | | |
Collapse
|
10
|
Abu-Amero KK. Leber's Hereditary Optic Neuropathy: The Mitochondrial Connection Revisited. Middle East Afr J Ophthalmol 2011; 18:17-23. [PMID: 21572729 PMCID: PMC3085146 DOI: 10.4103/0974-9233.75880] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
Our current understanding of Leber’s hereditary optic neuropathy (LHON)-mitochondrial connection falls short of comprehensive. Twenty years of intensive investigation have yielded a wealth of information about mitochondria, the mitochondrial genome, the metabolism of the optic nerve and other structures, and the phenotypic variability of classic LHON. However, we still cannot completely explain how primary LHON mutations injure the optic nerve or why the optic nerve is particularly at risk. We cannot explain the incomplete penetrance or the male predominance of LHON, the typical onset in young adult life without warning, or the synchronicity of visual loss. Moreover, primary LHON mutations clearly are not present in every family with the LHON phenotype (including multigenerational maternal inheritance), and they are present in only a minority of individuals who have the LHON optic neuropathy phenotype without a family history. All lines of evidence point to abnormalities of the mitochondria as the direct or indirect cause of LHON. Therefore, the mitochondria-LHON connection needs to be revisited and examined closely. This review will attempt to do that and provide an update on various aspects of LHON.
Collapse
Affiliation(s)
- Khaled K Abu-Amero
- Department of Ophthalmology, Ophthalmic Genetics Laboratory, College of Medicine, King Saud University, P. O. Box 245, Riyadh 11411, Saudi Arabia
| |
Collapse
|
11
|
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: 426] [Impact Index Per Article: 32.8] [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.
Collapse
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
Collapse
Affiliation(s)
- Patrick Yu-Wai-Man
- Mitochondrial Research Group, Institute for Ageing and Health, The Medical School, Newcastle University, UK.
| | | | | |
Collapse
|
12
|
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.
Collapse
|
13
|
Zou Y, Jia X, Zhang AM, Wang WZ, Li S, Guo X, Kong QP, Zhang Q, Yao YG. The MT-ND1 and MT-ND5 genes are mutational hotspots for Chinese families with clinical features of LHON but lacking the three primary mutations. Biochem Biophys Res Commun 2010; 399:179-85. [DOI: 10.1016/j.bbrc.2010.07.051] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2010] [Accepted: 07/15/2010] [Indexed: 02/03/2023]
|
14
|
Aggarwal D, Carelli V, Sadun AA. Genotype–phenotype correlations in mitochondrial optic neuropathies. EXPERT REVIEW OF OPHTHALMOLOGY 2009. [DOI: 10.1586/eop.09.32] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
|
15
|
Yu-Wai-Man P, Griffiths PG, Hudson G, Chinnery PF. Inherited mitochondrial optic neuropathies. J Med Genet 2009; 46:145-58. [PMID: 19001017 PMCID: PMC2643051 DOI: 10.1136/jmg.2007.054270] [Citation(s) in RCA: 281] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2008] [Revised: 09/08/2008] [Accepted: 10/07/2008] [Indexed: 02/02/2023]
Abstract
Leber hereditary optic neuropathy (LHON) and autosomal dominant optic atrophy (DOA) are the two most common inherited optic neuropathies and they result in significant visual morbidity among young adults. Both disorders are the result of mitochondrial dysfunction: LHON from primary mitochondrial DNA (mtDNA) mutations affecting the respiratory chain complexes; and the majority of DOA families have mutations in the OPA1 gene, which codes for an inner mitochondrial membrane protein critical for mtDNA maintenance and oxidative phosphorylation. Additional genetic and environmental factors modulate the penetrance of LHON, and the same is likely to be the case for DOA which has a markedly variable clinical phenotype. The selective vulnerability of retinal ganglion cells (RGCs) is a key pathological feature and understanding the fundamental mechanisms that underlie RGC loss in these disorders is a prerequisite for the development of effective therapeutic strategies which are currently limited.
Collapse
MESH Headings
- DNA, Mitochondrial
- Female
- GTP Phosphohydrolases/genetics
- Humans
- Male
- Optic Atrophy, Autosomal Dominant/diagnosis
- Optic Atrophy, Autosomal Dominant/epidemiology
- Optic Atrophy, Autosomal Dominant/genetics
- Optic Atrophy, Autosomal Dominant/pathology
- Optic Atrophy, Hereditary, Leber/diagnosis
- Optic Atrophy, Hereditary, Leber/epidemiology
- Optic Atrophy, Hereditary, Leber/genetics
- Optic Atrophy, Hereditary, Leber/pathology
- Point Mutation
Collapse
Affiliation(s)
- P Yu-Wai-Man
- Mitochondrial Research Group, The Medical School, Newcastle University, Newcastle upon Tyne, UK
- Department of Ophthalmology, Royal Victoria Infirmary, Newcastle upon Tyne, UK
| | - P G Griffiths
- Department of Ophthalmology, Royal Victoria Infirmary, Newcastle upon Tyne, UK
| | - G Hudson
- Mitochondrial Research Group, The Medical School, Newcastle University, Newcastle upon Tyne, UK
| | - P F Chinnery
- Mitochondrial Research Group, The Medical School, Newcastle University, Newcastle upon Tyne, UK
- Institute of Human Genetics, Newcastle University, Newcastle upon Tyne, NE1 3BZ, UK
| |
Collapse
|
16
|
Pello R, Martín MA, Carelli V, Nijtmans LG, Achilli A, Pala M, Torroni A, Gómez-Durán A, Ruiz-Pesini E, Martinuzzi A, Smeitink JA, Arenas J, Ugalde C. Mitochondrial DNA background modulates the assembly kinetics of OXPHOS complexes in a cellular model of mitochondrial disease. Hum Mol Genet 2008; 17:4001-11. [PMID: 18806273 DOI: 10.1093/hmg/ddn303] [Citation(s) in RCA: 127] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Leber's hereditary optic neuropathy (LHON), the most frequent mitochondrial disorder, is mostly due to three mitochondrial DNA (mtDNA) mutations in respiratory chain complex I subunit genes: 3460/ND1, 11778/ND4 and 14484/ND6. Despite considerable clinical evidences, a genetic modifying role of the mtDNA haplogroup background in the clinical expression of LHON remains experimentally unproven. We investigated the effect of mtDNA haplogroups on the assembly of oxidative phosphorylation (OXPHOS) complexes in transmitochondrial hybrids (cybrids) harboring the three common LHON mutations. The steady-state levels of respiratory chain complexes appeared normal in mutant cybrids. However, an accumulation of low molecular weight subcomplexes suggested a complex I assembly/stability defect, which was further demonstrated by reversibly inhibiting mitochondrial protein translation with doxycycline. Our results showed differentially delayed assembly rates of respiratory chain complexes I, III and IV amongst mutants belonging to different mtDNA haplogroups, revealing that specific mtDNA polymorphisms may modify the pathogenic potential of LHON mutations by affecting the overall assembly kinetics of OXPHOS complexes.
Collapse
Affiliation(s)
- Rosa Pello
- CIBERER-U723, Hospital Universitario 12 de Octubre, Madrid 28041, Spain
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
17
|
Hudson G, Yu-Wai-Man P, Chinnery PF. Leber hereditary optic neuropathy. EXPERT OPINION ON MEDICAL DIAGNOSTICS 2008; 2:789-99. [PMID: 23495818 DOI: 10.1517/17530059.2.7.789] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
BACKGROUND Leber hereditary optic neuropathy (LHON) is a cause of inherited blindness that typically presents with bilateral, painless, subacute visual failure in young adult males. Males are about four times more likely to be affected than females and 95% of LHON carriers become affected before the age of 50. Affected patients may have characteristic ocular fundal appearances and have evidence of optic nerve dysfunction in the form of impaired colour vision (dyschromatopsia), dense visual field defects (central or caecocentral scotoma) and abnormal visual electrophysiology. OBJECTIVES To summarise the current clinical approach to the molecular diagnosis and clinical management of LHON. METHODS To review the literature and present a review of current understanding. RESULTS/CONCLUSIONS The diagnosis of LHON is usually confirmed by molecular genetic analysis for one of three common mitochondrial DNA (mtDNA) mutations that all affect genes coding for complex I subunits of the respiratory chain: m.3460G > A, m.11778G > A and m.14484T > C. Sequencing of the entire mitochondrial genome can reveal the underlying cause in the minority of patients (∼ 5%) who do not harbour one of these three primary mutations, but a molecular diagnosis is not always possible. A minority of LHON patients exhibit a more widespread multi-system involvement with extra neurological features such as dystonia or a multiple sclerosis-like illness. Management is largely supportive, with the provision of low-vision aids, registration with the relevant social services and an important role for genetic counselling.
Collapse
Affiliation(s)
- Gavin Hudson
- Newcastle University, Mitochondrial Research Group, M4014, The Medical School, Framlington Place, Newcastle upon Tyne, NE2 4HH, UK +44 191 222 8233 ; +44 191 222 8553 ;
| | | | | |
Collapse
|
18
|
Wani AA, Ahanger SH, Bapat SA, Rangrez AY, Hingankar N, Suresh CG, Barnabas S, Patole MS, Shouche YS. Analysis of mitochondrial DNA sequences in childhood encephalomyopathies reveals new disease-associated variants. PLoS One 2007; 2:e942. [PMID: 17895983 PMCID: PMC1976591 DOI: 10.1371/journal.pone.0000942] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2007] [Accepted: 08/30/2007] [Indexed: 12/01/2022] Open
Abstract
Background Mitochondrial encephalomyopathies are a heterogeneous group of clinical disorders generally caused due to mutations in either mitochondrial DNA (mtDNA) or nuclear genes encoding oxidative phosphorylation (OXPHOS). We analyzed the mtDNA sequences from a group of 23 pediatric patients with clinical and morphological features of mitochondrial encephalopathies and tried to establish a relationship of identified variants with the disease. Methodology/Principle Findings Complete mitochondrial genomes were amplified by PCR and sequenced by automated DNA sequencing. Sequencing data was analyzed by SeqScape software and also confirmed by BLASTn program. Nucleotide sequences were compared with the revised Cambridge reference sequence (CRS) and sequences present in mitochondrial databases. The data obtained shows that a number of known and novel mtDNA variants were associated with the disease. Most of the non-synonymous variants were heteroplasmic (A4136G, A9194G and T11916A) suggesting their possibility of being pathogenic in nature. Some of the missense variants although homoplasmic were showing changes in highly conserved amino acids (T3394C, T3866C, and G9804A) and were previously identified with diseased conditions. Similarly, two other variants found in tRNA genes (G5783A and C8309T) could alter the secondary structure of Cys-tRNA and Lys-tRNA. Most of the variants occurred in single cases; however, a few occurred in more than one case (e.g. G5783A and A10149T). Conclusions and Significance The mtDNA variants identified in this study could be the possible cause of mitochondrial encephalomyopathies with childhood onset in the patient group. Our study further strengthens the pathogenic score of known variants previously reported as provisionally pathogenic in mitochondrial diseases. The novel variants found in the present study can be potential candidates for further investigations to establish the relationship between their incidence and role in expressing the disease phenotype. This study will be useful in genetic diagnosis and counseling of mitochondrial diseases in India as well as worldwide.
Collapse
Affiliation(s)
| | | | | | | | - Nitin Hingankar
- Division of Biochemical Sciences, National Chemical Laboratory, Pune, India
| | - C. G. Suresh
- Division of Biochemical Sciences, National Chemical Laboratory, Pune, India
| | - Shama Barnabas
- Division of Biochemical Sciences, National Chemical Laboratory, Pune, India
| | | | - Yogesh S. Shouche
- National Centre for Cell Science, Pune, India
- * To whom correspondence should be addressed. E-mail:
| |
Collapse
|
19
|
Sáfrány E, Csöngei V, Járomi L, Maász A, Magyari L, Sipeky C, Melegh B. Mitochondrial DNA and its mutations: novel fields in a new era. Orv Hetil 2007; 148:971-8. [PMID: 17513250 DOI: 10.1556/oh.2007.28014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Az utóbbi két évtizedet tartják a klinikai mitokondriális DNS-kutatás aranykorának. Folyamatosan bővül a patológiás variánsok száma, amelyek betegséggel társulnak, illetve bővül az ismeretanyag azokról az entitásokról, melyek hátterében a mitokondriális DNS kóros elváltozásai állnak. A cirkuláris mitokondriális DNS öröklődése eltér a Mendel-féle szabályoktól, anyai öröklésmenetet mutat; számos vonatkozásban eltérő sajátosságokkal rendelkezik a nukleáris DNS-hez viszonyítva. A molekuláris biológiai módszerek terjedésével egyre több kórkép ismerhető fel, noha a diagnosztika manapság is komoly kihívást jelent. Napjainkban a mitokondriális medicina számos orvosi szubspecialitáshoz kapcsolódóan jelentős előrelépéseket mutatott; így körvonalazódott a mitokondriális gasztroenterológia, endokrinológia, otológia, oftalmológia, nefrológia, hematológia, onkológia, reproduktív medicina és pszichiátria, mintegy az adott szubspecialitás mitokondriális DNS-sel kapcsolatos, többé-kevésbé részleges önállósodással megjelenő territóriuma. A jelen összefoglaló közlemény a mitokondriális medicina rövid, általános összefoglalása mellett e fejezetekre próbál rátekintést nyújtani.
Collapse
Affiliation(s)
- Eniko Sáfrány
- Pécsi Tudományegyetem, Altalános Orvostudományi Kar Orvosi Genetikai és Gyermekfejlodéstani Intézet, Pécs, Szigeti u. 12. 7624
| | | | | | | | | | | | | |
Collapse
|
20
|
Bandelt HJ, Salas A, Bravi CM. What is a 'novel' mtDNA mutation--and does 'novelty' really matter? J Hum Genet 2006; 51:1073-1082. [PMID: 17021933 DOI: 10.1007/s10038-006-0066-5] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2006] [Accepted: 08/29/2006] [Indexed: 01/08/2023]
Abstract
The hunt for pathogenic mitochondrial DNA (mtDNA) mutations is often fueled by the seeming novelty of mutations that are either nonsynonymous or affect the protein synthesis machinery in patients. In order to determine the novelty of a detected mutation, the working geneticist nearly always consults MITOMAP--often exclusively. By reanalyzing some case studies of refractory anemia with ring sideroblasts, prostate cancer, and hearing impairment, we demonstrate that the practice of solely relying on MITOMAP can be most misleading. A notorious example is the T1243C mutation, which was assessed to be novel and deemed to be associated with some (rare) disease simply because researchers did not realize that T1243C defines a deep branch in the Eurasian mtDNA phylogeny. The majority of 'novel' mutations suspected of being pathogenic are in actual fact known (and presumably neutral) polymorphisms (although unknown to MITOMAP), and this becomes glaringly evident when proper database searches and straightforward Internet queries are carried out.
Collapse
Affiliation(s)
- Hans-Jürgen Bandelt
- Department of Mathematics, University of Hamburg, Bundesstr. 55, 20146, Hamburg, Germany.
| | - Antonio Salas
- Unidad de Genética, Instituto de Medicina Legal, Facultad de Medicina, Universidad de Santiago de Compostela, 15782, Galicia, Spain
- Centro Nacional de Genotipado (CeGen), Hospital Clínico Universitario, 15706, Galicia, Spain
| | - Claudio M Bravi
- Laboratorio de Genética Molecular Poblacional, Instituto Multidisciplinario de Biología Celular (IMBICE), P.O. Box 403, 1900, La Plata, Argentina
| |
Collapse
|
21
|
Zhadanov SI, Atamanov VV, Zhadanov NI, Schurr TG. De novo COX2 mutation in a LHON family of Caucasian origin: implication for the role of mtDNA polymorphism in human pathology. J Hum Genet 2006; 51:161-170. [PMID: 16418878 DOI: 10.1007/s10038-005-0340-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2005] [Accepted: 10/31/2005] [Indexed: 12/27/2022]
Abstract
Recent studies suggest that certain mutations with phylogeographic importance as haplogroup markers may also influence the phenotypic expression of particular mitochondrial disorders. One such disorder, Leber's hereditary optic neuropathy (LHON), demonstrates a clear expression bias in mtDNAs belonging to haplogroup J, a West Eurasian maternal lineage defined by polymorphic markers that have been called 'secondary' disease mutations. In this report, we present evidence for a de novo heteroplasmic COX2 mutation associated with a LHON clinical phenotype. This particular mutation-at nucleotide position 7,598-occurs in West Eurasian haplogroup H, the most common maternal lineage among individuals of European descent, whereas previous studies have detected this mutation only in East Eurasian haplogroup E. A review of the available mtDNA sequence data indicates that the COX2 7598 mutation occurs as a homoplasic event at the tips of these phylogenetic branches, suggesting that it could be a variant that is rapidly eliminated by selection. This finding points to the potential background influence of polymorphisms on the expression of mild deleterious mutations such as LHON mtDNA defects and further highlights the difficulties in distinguishing deleterious mtDNA changes from neutral polymorphisms and their significance in the development of mitochondriopathies.
Collapse
Affiliation(s)
- Sergey I Zhadanov
- Department of Anthropology, University of Pennsylvania, 325 University Museum, 3260 South Street, Philadelphia, PA, 19104-6398, USA.
- Institute of Cytology and Genetics, SB Russian Academy of Sciences, Novosibirsk, Russia.
| | - Vasiliy V Atamanov
- Sv. Fyodorov State Institution, IRTC Eye Microsurgery, Novosibirsk, Russia
| | | | - Theodore G Schurr
- Department of Anthropology, University of Pennsylvania, 325 University Museum, 3260 South Street, Philadelphia, PA, 19104-6398, USA
| |
Collapse
|
22
|
Volodko NV, L’vova MA, Starikovskaya EB, Derbeneva OA, Bychkov IY, Mikhailovskaya IE, Pogozheva IV, Fedotov FF, Soyan GV, Procaccio V, Wallace DC, Sukernik RI. Spectrum of pathogenic mtDNA mutations in Leber’s hereditary optic neuropathy families from Siberia. RUSS J GENET+ 2006. [DOI: 10.1134/s102279540601011x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
|