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Pizzamiglio C, Hanna MG, Pitceathly RDS. Primary mitochondrial diseases. HANDBOOK OF CLINICAL NEUROLOGY 2024; 204:53-76. [PMID: 39322395 DOI: 10.1016/b978-0-323-99209-1.00004-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/27/2024]
Abstract
Primary mitochondrial diseases (PMDs) are a heterogeneous group of hereditary disorders characterized by an impairment of the mitochondrial respiratory chain. They are the most common group of genetic metabolic disorders, with a prevalence of 1 in 4,300 people. The presence of leukoencephalopathy is recognized as an important feature in many PMDs and can be a manifestation of mutations in both mitochondrial DNA (classic syndromes such as mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes; myoclonic epilepsy with ragged-red fibers [RRFs]; Leigh syndrome; and Kearns-Sayre syndrome) and nuclear DNA (mutations in maintenance genes such as POLG, MPV17, and TYMP; Leigh syndrome; and mitochondrial aminoacyl-tRNA synthetase disorders). In this chapter, PMDs associated with white matter involvement are outlined, including details of clinical presentations, brain MRI features, and elements of differential diagnoses. The current approach to the diagnosis of PMDs and management strategies are also discussed. A PMD diagnosis in a subject with leukoencephalopathy should be considered in the presence of specific brain MRI features (for example, cyst-like lesions, bilateral basal ganglia lesions, and involvement of both cerebral hemispheres and cerebellum), in addition to a complex neurologic or multisystem disorder. Establishing a genetic diagnosis is crucial to ensure appropriate genetic counseling, multidisciplinary team input, and eligibility for clinical trials.
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Affiliation(s)
- Chiara Pizzamiglio
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London, United Kingdom; NHS Highly Specialised Service for Rare Mitochondrial Disorders, Queen Square Centre for Neuromuscular Diseases, National Hospital for Neurology and Neurosurgery, London, United Kingdom
| | - Michael G Hanna
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London, United Kingdom; NHS Highly Specialised Service for Rare Mitochondrial Disorders, Queen Square Centre for Neuromuscular Diseases, National Hospital for Neurology and Neurosurgery, London, United Kingdom
| | - Robert D S Pitceathly
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London, United Kingdom; NHS Highly Specialised Service for Rare Mitochondrial Disorders, Queen Square Centre for Neuromuscular Diseases, National Hospital for Neurology and Neurosurgery, London, United Kingdom.
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Abstract
The progressive myoclonic epilepsies (PMEs) represent a rare but devastating group of syndromes characterized by epileptic myoclonus, typically action-induced seizures, neurological regression, medically refractory epilepsy, and a variety of other signs and symptoms depending on the specific syndrome. Most of the PMEs begin in children who are developing as expected, with the onset of the disorder heralded by myoclonic and other seizure types. The conditions are considerably heterogenous, but medical intractability to epilepsy, particularly myoclonic seizures, is a core feature. With the increasing use of molecular genetic techniques, mutations and their abnormal protein products are being delineated, providing a basis for disease-based therapy. However, genetic and enzyme replacement or substrate removal are in the nascent stage, and the primary therapy is through antiepileptic drugs. Epilepsy in children with progressive myoclonic seizures is notoriously difficult to treat. The disorder is rare, so few double-blinded, placebo-controlled trials have been conducted in PME, and drugs are chosen based on small open-label trials or extrapolation of data from drug trials of other syndromes with myoclonic seizures. This review discusses the major PME syndromes and their neurogenetic basis, pathophysiological underpinning, electroencephalographic features, and currently available treatments.
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Affiliation(s)
- Gregory L Holmes
- Department of Neurological Sciences, Larner College of Medicine, University of Vermont College of Medicine, Stafford Hall, 118C, Burlington, VT, 05405, USA.
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Set KK, Sen K, Huq AHM, Agarwal R. Mitochondrial Disorders of the Nervous System: A Review. Clin Pediatr (Phila) 2019; 58:381-394. [PMID: 30607979 DOI: 10.1177/0009922818821890] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Kallol K Set
- 1 Dayton Children's Hospital, Dayton, OH, USA.,2 Wright State University Boonshoft School of Medicine, Dayton, OH, USA
| | - Kuntal Sen
- 3 Children's Hospital of Michigan, Detroit, MI, USA.,4 Wayne State University School of Medicine, Detroit, MI, USA
| | - A H M Huq
- 3 Children's Hospital of Michigan, Detroit, MI, USA.,4 Wayne State University School of Medicine, Detroit, MI, USA
| | - Rajkumar Agarwal
- 1 Dayton Children's Hospital, Dayton, OH, USA.,2 Wright State University Boonshoft School of Medicine, Dayton, OH, USA
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Ban R, Guo JH, Pu CQ, Shi Q, Liu HX, Zhang YT. A Novel Mutation of Mitochondrial T14709C Causes Myoclonic Epilepsy with Ragged Red Fibers Syndrome in a Chinese Patient. Chin Med J (Engl) 2018; 131:1569-1574. [PMID: 29941710 PMCID: PMC6032686 DOI: 10.4103/0366-6999.235120] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
Background: Myoclonic epilepsy with ragged red fibers (MERRF) syndrome is characterized by myoclonus, generalized epilepsy, cerebellar ataxia, and ragged red fibers (RRFs) in the muscle. T-to-C transition at nucleotide position 14709 in the mitochondrial tRNA glutamic acid (tRNAGlu) gene has previously been associated with maternally inherited diabetes and deafness. However, the association between MERRF and mitochondrial T14709C mutation (m.T14709C) has never been reported before. Methods: Clinical information of a 17-year-old patient was collected; muscle biopsy and next-generation sequencing (NGS) of whole mitochondrial and neuromuscular disease panel were then conducted. Finally, sanger sequencing was carried out to confirm the mutations. Results: The patient presented a typical MERRF phenotype with muscle weakness, epileptic seizure, clonic episodes, cerebellar ataxia, and spinal scoliosis. Muscle biopsy showed RRFs which indicated abnormal mitochondrial functions. NGS of whole mitochondrial gene revealed m.T14709C mutation, confirmed by Sanger sequencing. Conclusion: We present a sporadic patient with typical MERRF presentation carrying the mutation of m.T14709C, which expanded the spectrum of m.T14709C.
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Affiliation(s)
- Rui Ban
- Department of Neurology, Chinese People's Liberation Army General Hospital, Beijing 100853; Department of Neurology, School of Medicine, Nankai University, Tianjin 300071, China
| | - Jun-Hong Guo
- Department of Neurology, The First Hospital of Shanxi Medical University, Taiyuan, Shanxi 030001, China
| | - Chuan-Qiang Pu
- Department of Neurology, Chinese People's Liberation Army General Hospital, Beijing 100853, China
| | - Qiang Shi
- Department of Neurology, Chinese People's Liberation Army General Hospital, Beijing 100853, China
| | - Hua-Xu Liu
- Department of Neurology, Chinese People's Liberation Army General Hospital, Beijing 100853, China
| | - Yu-Tong Zhang
- Department of Neurology, Chinese People's Liberation Army General Hospital, Beijing 100853, China
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Lorenzoni PJ, Scola RH, Kay CSK, Silvado CES, Werneck LC. When should MERRF (myoclonus epilepsy associated with ragged-red fibers) be the diagnosis? ARQUIVOS DE NEURO-PSIQUIATRIA 2015; 72:803-11. [PMID: 25337734 DOI: 10.1590/0004-282x20140124] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2014] [Accepted: 07/22/2014] [Indexed: 11/22/2022]
Abstract
Myoclonic epilepsy associated with ragged red fibers (MERRF) is a rare mitochondrial disorder. Diagnostic criteria for MERRF include typical manifestations of the disease: myoclonus, generalized epilepsy, cerebellar ataxia and ragged red fibers (RRF) on muscle biopsy. Clinical features of MERRF are not necessarily uniform in the early stages of the disease, and correlations between clinical manifestations and physiopathology have not been fully elucidated. It is estimated that point mutations in the tRNALys gene of the DNAmt, mainly A8344G, are responsible for almost 90% of MERRF cases. Morphological changes seen upon muscle biopsy in MERRF include a substantive proportion of RRF, muscle fibers showing a deficient activity of cytochrome c oxidase (COX) and the presence of vessels with a strong reaction for succinate dehydrogenase and COX deficiency. In this review, we discuss mainly clinical and laboratory manifestations, brain images, electrophysiological patterns, histology and molecular findings as well as some differential diagnoses and treatments.
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Affiliation(s)
- Paulo José Lorenzoni
- Departamento de Neurologia, Hospital de Clínicas, Universidade Federal do Paraná, Curitiba, PR, Brazil
| | - Rosana Herminia Scola
- Departamento de Neurologia, Hospital de Clínicas, Universidade Federal do Paraná, Curitiba, PR, Brazil
| | - Cláudia Suemi Kamoi Kay
- Departamento de Neurologia, Hospital de Clínicas, Universidade Federal do Paraná, Curitiba, PR, Brazil
| | - Carlos Eduardo S Silvado
- Departamento de Neurologia, Hospital de Clínicas, Universidade Federal do Paraná, Curitiba, PR, Brazil
| | - Lineu Cesar Werneck
- Departamento de Neurologia, Hospital de Clínicas, Universidade Federal do Paraná, Curitiba, PR, Brazil
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"Myo-cardiomyopathy" is commonly associated with the A8344G "MERRF" mutation. J Neurol 2015; 262:701-10. [PMID: 25559684 DOI: 10.1007/s00415-014-7632-0] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2014] [Revised: 12/22/2014] [Accepted: 12/24/2014] [Indexed: 10/24/2022]
Abstract
The objective of the study was to better characterize the clinical phenotype associated with the A8344G "MERRF" mutation of mitochondrial DNA. Fifteen mutated patients were extensively investigated. The frequency of main clinical features was: exercise intolerance and/or muscle weakness 67 %, respiratory involvement 67 %, lactic acidosis 67 %, cardiac abnormalities 53 %, peripheral neuropathy 47 %, myoclonus 40 %, epilepsy 40 %, ataxia 13 %. A restrictive respiratory insufficiency requiring ventilatory support was observed in about half of our patients. One patient developed a severe and rapidly progressive cardiomyopathy requiring cardioverter-defibrillator implantation. Five patients died of overwhelming, intractable lactic acidosis. Serial muscle MRIs identified a consistent pattern of muscle involvement and progression. Cardiac MRI showed non-ischemic late gadolinium enhancement in the left ventricle inferolateral part as early sign of myocardial involvement. Brain spectroscopy demonstrated increased peak of choline and reduction of N-acetylaspartate. Lactate was never detected in brain areas, while it could be documented in ventricles. We confirm that muscle involvement is the most frequent clinical feature associated with A8443G mutation. In contrast with previous reports, however, about half of our patients did not develop signs of CNS involvement even in later stages of the disease. The difference may be related to the infrequent investigation of A8344G mutation in 'pure' mitochondrial myo-cardiomyopathy, representing a bias and a possible cause of syndrome's underestimation. Our study highlights the importance of lactic acidosis and respiratory muscle insufficiency as critical prognostic factors. Muscle and cardiac MRI and brain spectroscopy may be useful tools in diagnosis and follow-up of MERRF.
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Lorenzoni PJ, Scola RH, Kay CSK, Arndt RC, Silvado CE, Werneck LC. MERRF: Clinical features, muscle biopsy and molecular genetics in Brazilian patients. Mitochondrion 2011; 11:528-32. [DOI: 10.1016/j.mito.2011.01.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2010] [Revised: 01/11/2011] [Accepted: 01/24/2011] [Indexed: 11/25/2022]
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Ito S, Shirai W, Asahina M, Hattori T. Clinical and brain MR imaging features focusing on the brain stem and cerebellum in patients with myoclonic epilepsy with ragged-red fibers due to mitochondrial A8344G mutation. AJNR Am J Neuroradiol 2007; 29:392-5. [PMID: 17989367 DOI: 10.3174/ajnr.a0865] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
SUMMARY We report 3 patients with myoclonic epilepsy with ragged-red fibers (MERRF) diagnosed by mitochondrial A8344G mutation. Cerebellar ataxia was the first symptom in all patients. Conventional brain MR imaging showed atrophy of the superior cerebellar peduncles and the cerebellum in all patients and brain stem atrophy in 2 patients. In diffusion tensor analysis, fractional anisotropy of the superior cerebellar peduncles was mildly decreased in 1 patient. There was a discrepancy between clinical disabilities (severe) and radiologic abnormalities (mild). This discrepancy and atrophy of the superior cerebellar peduncles and the cerebellum may be important findings suggesting a diagnosis of MERRF.
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Affiliation(s)
- S Ito
- Department of Neurology, Graduate School of Medicine, Chiba University, Chiba, Japan.
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Abstract
The central nervous system (CNS) is, after the peripheral nervous system, the second most frequently affected organ in mitochondrial disorders (MCDs). CNS involvement in MCDs is clinically heterogeneous, manifesting as epilepsy, stroke-like episodes, migraine, ataxia, spasticity, extrapyramidal abnormalities, bulbar dysfunction, psychiatric abnormalities, neuropsychological deficits, or hypophysial abnormalities. CNS involvement is found in syndromic and non-syndromic MCDs. Syndromic MCDs with CNS involvement include mitochondrial encephalomyopathy, lactacidosis, stroke-like episodes syndrome, myoclonic epilepsy and ragged red fibers syndrome, mitochondrial neuro-gastrointestinal encephalomyopathy syndrome, neurogenic muscle weakness, ataxia, and retinitis pigmentosa syndrome, mitochondrial depletion syndrome, Kearns-Sayre syndrome, and Leigh syndrome, Leber's hereditary optic neuropathy, Friedreich's ataxia, and multiple systemic lipomatosis. As CNS involvement is often subclinical, the CNS including the spinal cord should be investigated even in the absence of overt clinical CNS manifestations. CNS investigations comprise the history, clinical neurological examination, neuropsychological tests, electroencephalogram, cerebral computed tomography scan, and magnetic resonance imaging. A spinal tap is indicated if there is episodic or permanent impaired consciousness or in case of cognitive decline. More sophisticated methods are required if the CNS is solely affected. Treatment of CNS manifestations in MCDs is symptomatic and focused on epilepsy, headache, lactacidosis, impaired consciousness, confusion, spasticity, extrapyramidal abnormalities, or depression. Valproate, carbamazepine, corticosteroids, acetyl salicylic acid, local and volatile anesthetics should be applied with caution. Avoiding certain drugs is often more beneficial than application of established, apparently indicated drugs.
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Affiliation(s)
- J Finsterer
- Krankenanstalt Rudolfstiftung, Vienna, Austria.
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Nakazato Y, Nagashima K. Encephalomyelitis, brain tumors, neuromuscular diseases and miscellaneous disorders. Neuropathology 2000; 20 Suppl:S8-13. [PMID: 11037180 DOI: 10.1046/j.1440-1789.2000.00324.x] [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: 11/20/2022]
Abstract
Japanese neuropathologists have accomplished and contributed to a considerable number of achievements, and some of these are cited in other articles in this issue. Several of these achievements as well as other miscellaneous discoveries are briefly summarized in the present paper. Specifically these relate to rabies postvaccinal encephalomyelitis, experimental allergic encephalomyelitis, brain tumor research, neuromuscular disorders, schizophrenia, viral infections, glial inclusion body in multiple system atrophy, and the neurobiology of glia.
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Affiliation(s)
- Y Nakazato
- Department of Pathology, Gunma University School of Medicine, Maebashi, Japan
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Arpa J, Campos Y, Gutiérrez-Molina M, Martin-Casanueva MA, Cruz-Martínez A, Pérez-Conde MC, López-Pajares R, Morales MC, Tatay J, Lacasa T, Barreiro P, Arenas J. Gene dosage effect in one family with myoclonic epilepsy and ragged-red fibers (MERRF). Acta Neurol Scand 1997; 96:65-71. [PMID: 9272179 DOI: 10.1111/j.1600-0404.1997.tb00241.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
OBJECTIVES We analyzed the percentage of mitochondrial DNA (mtDNA) heteroplasmy in blood samples of 13 individuals belonging to a three family generation of myoclonic epilepsy with ragged-red fibers (MERRF) and compared the 5 affected patients and the 8 unaffected relatives. MATERIAL AND METHODS DNA was extracted from blood and muscle of the proband and from blood of 12 maternal relatives. A PCR restriction analysis method was used to detect the mutation. RESULTS The proband had the complete MERRF phenotype. The phenotype in three other individuals in the maternal lineage was consistent with the MERRF syndrome. The remaining were asymptomatic. The np 8344 mutation was observed in muscle and blood of the proband, and in blood from every one of 12 maternal relatives, ranging from 44% to 83% of mutated genomes. Symptomatic individuals had higher levels (P < 0.001) of mutated mtDNA than asymptomatic maternal relatives. However, high proportions of mutant genomes (up to 63%) were found in asymptomatic relatives. CONCLUSIONS Although there seems to be a gene dosage effect in MERRF, we found no absolute relationship between the relative proportion of mutant genomes in blood and clinical severity. Factors other than gene dosage in blood may account for the differences in clinical phenotype.
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Affiliation(s)
- J Arpa
- Department of Neurology, Hospital La Paz, Madrid, Spain
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