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Ripolone M, Zanotti S, Napoli L, Ronchi D, Ciscato P, Comi GP, Moggio M, Sciacco M. MERRF Mutation A8344G in a Four-Generation Family without Central Nervous System Involvement: Clinical and Molecular Characterization. J Pers Med 2023; 13:jpm13010147. [PMID: 36675808 PMCID: PMC9865457 DOI: 10.3390/jpm13010147] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2022] [Revised: 01/10/2023] [Accepted: 01/10/2023] [Indexed: 01/14/2023] Open
Abstract
A 53-year-old man approached our Neuromuscular Unit following an incidental finding of hyperckemia. Similar to his mother who had died at the age of 77 years, he was diabetic and had a few lipomas. The patient's two sisters, aged 60 and 50 years, did not have any neurological symptoms. Proband's skeletal muscle biopsy showed several COX-negative fibers, many of which were "ragged red". Genetic analysis revealed the presence of the A8344G mtDNA mutation, which is most commonly associated with a maternally inherited multisystem mitochondrial disorder known as MERRF (myoclonus epilepsy with ragged-red fibers). The two sisters also carry the mutation. Family members on the maternal side were reported healthy. Although atypical phenotypes have been reported in association with the A8344G mutation, central nervous system (CSN) manifestations other than myoclonic epilepsy are always reported in the family tree. If present, our four-generation family manifestations are late-onset and do not affect CNS. This could be explained by the fact that the mutational load remains low and therefore prevents tissues/organs from reaching the pathologic threshold. The fact that this occurs throughout generations and that CNS, which has the highest energetic demand, is clinically spared, suggests that regulatory genes and/or pathways affect mitochondrial segregation and replication, and protect organs from progressive dysfunction.
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Affiliation(s)
- Michela Ripolone
- Neuromuscular and Rare Diseases Unit, Department of Neuroscience, Foundation IRCCS Ca’ Granda Ospedale Maggiore Policlinico, 20122 Milan, Italy
| | - Simona Zanotti
- Neuromuscular and Rare Diseases Unit, Department of Neuroscience, Foundation IRCCS Ca’ Granda Ospedale Maggiore Policlinico, 20122 Milan, Italy
| | - Laura Napoli
- Neuromuscular and Rare Diseases Unit, Department of Neuroscience, Foundation IRCCS Ca’ Granda Ospedale Maggiore Policlinico, 20122 Milan, Italy
| | - Dario Ronchi
- Dino Ferrari Center, Department of Pathophysiology and Transplantation (DEPT), University of Milan, 20122 Milan, Italy
| | - Patrizia Ciscato
- Neuromuscular and Rare Diseases Unit, Department of Neuroscience, Foundation IRCCS Ca’ Granda Ospedale Maggiore Policlinico, 20122 Milan, Italy
| | - Giacomo Pietro Comi
- Neuromuscular and Rare Diseases Unit, Department of Neuroscience, Foundation IRCCS Ca’ Granda Ospedale Maggiore Policlinico, 20122 Milan, Italy
- Dino Ferrari Center, Department of Pathophysiology and Transplantation (DEPT), University of Milan, 20122 Milan, Italy
| | - Maurizio Moggio
- Neuromuscular and Rare Diseases Unit, Department of Neuroscience, Foundation IRCCS Ca’ Granda Ospedale Maggiore Policlinico, 20122 Milan, Italy
| | - Monica Sciacco
- Neuromuscular and Rare Diseases Unit, Department of Neuroscience, Foundation IRCCS Ca’ Granda Ospedale Maggiore Policlinico, 20122 Milan, Italy
- Correspondence: ; Tel.: +39-0255-036-504
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Zavattaro E, Lunardon C, Coppo L, Savoia P, Colombo E, Comi C, Cantello R. Is There any Link between Madelung Disease and Ischemic Stroke? A Case Report. Neurol India 2022; 70:2166-2168. [DOI: 10.4103/0028-3886.359251] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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3
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Richter U, McFarland R, Taylor RW, Pickett SJ. The molecular pathology of pathogenic mitochondrial tRNA variants. FEBS Lett 2021; 595:1003-1024. [PMID: 33513266 PMCID: PMC8600956 DOI: 10.1002/1873-3468.14049] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Revised: 01/14/2021] [Accepted: 01/18/2021] [Indexed: 12/16/2022]
Abstract
Mitochondrial diseases are clinically and genetically heterogeneous disorders, caused by pathogenic variants in either the nuclear or mitochondrial genome. This heterogeneity is particularly striking for disease caused by variants in mitochondrial DNA‐encoded tRNA (mt‐tRNA) genes, posing challenges for both the treatment of patients and understanding the molecular pathology. In this review, we consider disease caused by the two most common pathogenic mt‐tRNA variants: m.3243A>G (within MT‐TL1, encoding mt‐tRNALeu(UUR)) and m.8344A>G (within MT‐TK, encoding mt‐tRNALys), which together account for the vast majority of all mt‐tRNA‐related disease. We compare and contrast the clinical disease they are associated with, as well as their molecular pathologies, and consider what is known about the likely molecular mechanisms of disease. Finally, we discuss the role of mitochondrial–nuclear crosstalk in the manifestation of mt‐tRNA‐associated disease and how research in this area not only has the potential to uncover molecular mechanisms responsible for the vast clinical heterogeneity associated with these variants but also pave the way to develop treatment options for these devastating diseases.
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Affiliation(s)
- Uwe Richter
- Wellcome Centre for Mitochondrial Research, The Medical School, Newcastle University, UK.,Molecular and Integrative Biosciences Research Programme, Faculty of Biological and Environmental Sciences, University of Helsinki, Finland.,Newcastle University Biosciences Institute, Newcastle University, UK
| | - Robert McFarland
- Wellcome Centre for Mitochondrial Research, The Medical School, Newcastle University, UK.,Newcastle University Translational and Clinical Research Institute, Newcastle University, UK
| | - Robert W Taylor
- Wellcome Centre for Mitochondrial Research, The Medical School, Newcastle University, UK.,Newcastle University Translational and Clinical Research Institute, Newcastle University, UK
| | - Sarah J Pickett
- Wellcome Centre for Mitochondrial Research, The Medical School, Newcastle University, UK.,Newcastle University Translational and Clinical Research Institute, Newcastle University, UK
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4
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La Morgia C, Maresca A, Caporali L, Valentino ML, Carelli V. Mitochondrial diseases in adults. J Intern Med 2020; 287:592-608. [PMID: 32463135 DOI: 10.1111/joim.13064] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Revised: 02/07/2020] [Accepted: 02/21/2020] [Indexed: 02/07/2023]
Abstract
Mitochondrial medicine is a field that expanded exponentially in the last 30 years. Individually rare, mitochondrial diseases as a whole are probably the most frequent genetic disorder in adults. The complexity of their genotype-phenotype correlation, in terms of penetrance and clinical expressivity, natural history and diagnostic algorithm derives from the dual genetic determination. In fact, in addition to the about 1.500 genes encoding mitochondrial proteins that reside in the nuclear genome (nDNA), we have the 13 proteins encoded by the mitochondrial genome (mtDNA), for which 22 specific tRNAs and 2 rRNAs are also needed. Thus, besides Mendelian genetics, we need to consider all peculiarities of how mtDNA is inherited, maintained and expressed to fully understand the pathogenic mechanisms of these disorders. Yet, from the initial restriction to the narrow field of oxidative phosphorylation dysfunction, the landscape of mitochondrial functions impinging on cellular homeostasis, driving life and death, is impressively enlarged. Finally, from the clinical standpoint, starting from the neuromuscular field, where brain and skeletal muscle were the primary targets of mitochondrial dysfunction as energy-dependent tissues, after three decades virtually any subspecialty of medicine is now involved. We will summarize the key clinical pictures and pathogenic mechanisms of mitochondrial diseases in adults.
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Affiliation(s)
- C La Morgia
- From the, Dipartimento di Scienze Biomediche e Neuromotorie, Università di Bologna, Bologna, Italy.,IRCCS Istituto delle Scienze Neurologiche di Bologna, UOC Clinica Neurologica, Bologna, Italy
| | - A Maresca
- IRCCS Istituto delle Scienze Neurologiche di Bologna, UOC Clinica Neurologica, Bologna, Italy
| | - L Caporali
- IRCCS Istituto delle Scienze Neurologiche di Bologna, UOC Clinica Neurologica, Bologna, Italy
| | - M L Valentino
- From the, Dipartimento di Scienze Biomediche e Neuromotorie, Università di Bologna, Bologna, Italy.,IRCCS Istituto delle Scienze Neurologiche di Bologna, UOC Clinica Neurologica, Bologna, Italy
| | - V Carelli
- From the, Dipartimento di Scienze Biomediche e Neuromotorie, Università di Bologna, Bologna, Italy.,IRCCS Istituto delle Scienze Neurologiche di Bologna, UOC Clinica Neurologica, Bologna, Italy
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Abstract
INTRODUCTION Epilepsy is a prominent feature of myoclonic epilepsy with ragged-red fibers (MERRF)-syndrome. The most frequent seizure type is myoclonic seizures, of which the treatment is challenging and empiric. AREAS COVERED Herein, the author summarises and discusses previous and recent findings of antiepileptic drug (AED) treatment in MERRF-syndrome. EXPERT OPINION MERRF-syndrome is a predominantly maternally inherited, multisystem mitochondrial disorder caused by pathogenic variants predominantly of the mitochondrial DNA (mtDNA). Canonical clinical features of MERRF include myoclonus, epilepsy, ataxia, and myopathy. Additionally, other manifestations in the CNS, peripheral nerves, eyes, ears, heart, gastrointestinal tract, and endocrine organs may occur (MERRF-plus). Today, MERRF is considered rather as myoclonic ataxia than as myoclonic epilepsy. Genotypically, MERRF is due to mutations in 13 mtDNA-located genes and 1 nDNA-located gene. According to the modified Smith-score, the strongest gene-disease relationship exists for MT-TK, MT-TL1, and POLG1. Epilepsy is the second most frequent phenotypic feature of MERRF. Seizure-types associated with MERRF include focal myoclonic, focal clonic, and focal atonic seizures, generalized myoclonic, tonic-clonic, atonic, and myoclonic-atonic seizures, or typical absences. Treatment of myoclonic epilepsy relies on expert judgments recommending levetiracetam, together with clonazepam, or topiramate, zonisamide, or piracetam in monotherapy as the first line AEDs.
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Affiliation(s)
- Josef Finsterer
- a Krankenanstalt Rudolfstiftung , Messerli Institute , Vienna , Austria
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Miyahara H, Matsumoto S, Mokuno K, Dei R, Akagi A, Mimuro M, Iwasaki Y, Yoshida M. Autopsied case with MERRF/MELAS overlap syndrome accompanied by stroke-like episodes localized to the precentral gyrus. Neuropathology 2019; 39:212-217. [PMID: 30972844 PMCID: PMC6850640 DOI: 10.1111/neup.12551] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2019] [Revised: 02/20/2019] [Accepted: 02/21/2019] [Indexed: 11/29/2022]
Abstract
We present an autopsied case with A8344G-mutated myoclonus epilepsy with ragged red fibers (MERRF)/mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS) overlap syndrome accompanied by stroke-like episodes localized to the precentral gyrus. A 16-year-old Japanese woman suddenly experienced repetitive consciousness disturbances with increased serum lactate and creatine kinase levels. Magnetic resonance imaging showed abnormal intensity of bilateral precentral gyrus. She was clinically diagnosed as having a mitochondrial disorder and the A8344G mutation was detected in mitochondrial DNA. At 17 years of age, she died from congestive heart failure secondary to a third episode of lactic acidosis. Neuropatho-logically, multifocal laminar necrosis, which is responsible for stroke-like episodes in MELAS, was seen in the frontal cortex including the precentral gyrus, but there was no neuronal loss and gliosis in the basal ganglia, cerebellum, and brainstem, which were compatible with MERRF. Hypertrophy of the vascular smooth muscle and choroidal epithelium were seen, and were strongly visualized by an anti-mitochondrial antibody. Skeletal muscles showed uneven muscular diameters, increased central nuclei, and ragged red fibers (RRFs). Decreased cytochrome c oxidase (COX) activity and strongly succinate dehydrogenase (SDH)-reactive blood vessels were also noted. Stroke-like episodes in MERRF/MELAS overlap syndrome are thought to be rare in the frontal cortex including the precentral gyrus. Only two cases of MERRF/MELAS overlap syndrome with A8344G mutation, including this case, have shown stroke-like episodes in the frontal lobes. Other than the A8344G mutation and frontal lobe involvement, they had a high degree of similarity in terms of presence of RRFs, gastrointestinal dysfunction, and lack of typical MERRF neuropathology. In conclusion, this is an important case describing the clinical spectrum associated with A8344G-mutated MERRF/MELAS overlap syndrome.
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Affiliation(s)
- Hiroaki Miyahara
- Department of Neuropathology, Institute for Medical Science of Aging, Aichi Medical University, Nagakute, Japan
| | | | - Kenji Mokuno
- Department of Neurology, Toyohashi Municipal Hospital, Toyohashi, Japan
| | - Rika Dei
- Department of Neurology, Toyohashi Municipal Hospital, Toyohashi, Japan
| | - Akio Akagi
- Department of Neuropathology, Institute for Medical Science of Aging, Aichi Medical University, Nagakute, Japan
| | - Maya Mimuro
- Department of Neuropathology, Institute for Medical Science of Aging, Aichi Medical University, Nagakute, Japan
| | - Yasushi Iwasaki
- Department of Neuropathology, Institute for Medical Science of Aging, Aichi Medical University, Nagakute, Japan
| | - Mari Yoshida
- Department of Neuropathology, Institute for Medical Science of Aging, Aichi Medical University, Nagakute, Japan
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7
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Abstract
BACKGROUND Given the etiologic heterogeneity of disease classification using clinical phenomenology, we employed contemporary criteria to classify variants associated with myoclonic epilepsy with ragged-red fibers (MERRF) syndrome and to assess the strength of evidence of gene-disease associations. Standardized approaches are used to clarify the definition of MERRF, which is essential for patient diagnosis, patient classification, and clinical trial design. METHODS Systematic literature and database search with application of standardized assessment of gene-disease relationships using modified Smith criteria and of variants reported to be associated with MERRF using modified Yarham criteria. RESULTS Review of available evidence supports a gene-disease association for two MT-tRNAs and for POLG. Using modified Smith criteria, definitive evidence of a MERRF gene-disease association is identified for MT-TK. Strong gene-disease evidence is present for MT-TL1 and POLG. Functional assays that directly associate variants with oxidative phosphorylation impairment were critical to mtDNA variant classification. In silico analysis was of limited utility to the assessment of individual MT-tRNA variants. With the use of contemporary classification criteria, several mtDNA variants previously reported as pathogenic or possibly pathogenic are reclassified as neutral variants. CONCLUSIONS MERRF is primarily an MT-TK disease, with pathogenic variants in this gene accounting for ~90% of MERRF patients. Although MERRF is phenotypically and genotypically heterogeneous, myoclonic epilepsy is the clinical feature that distinguishes MERRF from other categories of mitochondrial disorders. Given its low frequency in mitochondrial disorders, myoclonic epilepsy is not explained simply by an impairment of cellular energetics. Although MERRF phenocopies can occur in other genes, additional data are needed to establish a MERRF disease-gene association. This approach to MERRF emphasizes standardized classification rather than clinical phenomenology, thus improving patient diagnosis and clinical trial design.
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Jeppesen TD, Al-Hashimi N, Duno M, Wibrand F, Andersen G, Vissing J. Mitochondrial DNA mutation load in a family with the m.8344A>G point mutation and lipomas: a case study. Clin Case Rep 2017; 5:2034-2039. [PMID: 29225851 PMCID: PMC5715413 DOI: 10.1002/ccr3.1096] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2016] [Revised: 06/16/2017] [Accepted: 06/21/2017] [Indexed: 11/12/2022] Open
Abstract
Studies have shown that difference in mtDNA mutation load among tissues is a result of postnatal modification. We present five family members with the m.8344A>G with variable phenotypes but uniform intrapersonal distribution of mutation load, indicating that there is no postnatal modification of mtDNA mutation load in this genotype.
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Affiliation(s)
- Tina Dysgaard Jeppesen
- Copenhagen Neuromuscular Clinic Rigshospitalet University of Copenhagen Copenhagen Denmark
| | - Noor Al-Hashimi
- Copenhagen Neuromuscular Clinic Rigshospitalet University of Copenhagen Copenhagen Denmark
| | - Morten Duno
- Department of Clinical Genetics Rigshospitalet University of Copenhagen Copenhagen Denmark
| | - Flemming Wibrand
- Department of Clinical Genetics Rigshospitalet University of Copenhagen Copenhagen Denmark
| | - Grete Andersen
- Copenhagen Neuromuscular Clinic Rigshospitalet University of Copenhagen Copenhagen Denmark
| | - John Vissing
- Copenhagen Neuromuscular Clinic Rigshospitalet University of Copenhagen Copenhagen Denmark
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9
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Finsterer J, Zarrouk-Mahjoub S. Management of epilepsy in MERRF syndrome. Seizure 2017; 50:166-170. [DOI: 10.1016/j.seizure.2017.06.010] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Revised: 05/26/2017] [Accepted: 06/13/2017] [Indexed: 11/28/2022] Open
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10
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Alston CL, Rocha MC, Lax NZ, Turnbull DM, Taylor RW. The genetics and pathology of mitochondrial disease. J Pathol 2016; 241:236-250. [PMID: 27659608 PMCID: PMC5215404 DOI: 10.1002/path.4809] [Citation(s) in RCA: 263] [Impact Index Per Article: 32.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Revised: 09/15/2016] [Accepted: 09/16/2016] [Indexed: 12/30/2022]
Abstract
Mitochondria are double-membrane-bound organelles that are present in all nucleated eukaryotic cells and are responsible for the production of cellular energy in the form of ATP. Mitochondrial function is under dual genetic control - the 16.6-kb mitochondrial genome, with only 37 genes, and the nuclear genome, which encodes the remaining ∼1300 proteins of the mitoproteome. Mitochondrial dysfunction can arise because of defects in either mitochondrial DNA or nuclear mitochondrial genes, and can present in childhood or adulthood in association with vast clinical heterogeneity, with symptoms affecting a single organ or tissue, or multisystem involvement. There is no cure for mitochondrial disease for the vast majority of mitochondrial disease patients, and a genetic diagnosis is therefore crucial for genetic counselling and recurrence risk calculation, and can impact on the clinical management of affected patients. Next-generation sequencing strategies are proving pivotal in the discovery of new disease genes and the diagnosis of clinically affected patients; mutations in >250 genes have now been shown to cause mitochondrial disease, and the biochemical, histochemical, immunocytochemical and neuropathological characterization of these patients has led to improved diagnostic testing strategies and novel diagnostic techniques. This review focuses on the current genetic landscape associated with mitochondrial disease, before focusing on advances in studying associated mitochondrial pathology in two, clinically relevant organs - skeletal muscle and brain. © 2016 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.
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Affiliation(s)
- Charlotte L Alston
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Newcastle upon Tyne, UK
| | - Mariana C Rocha
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Newcastle upon Tyne, UK
| | - Nichola Z Lax
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Newcastle upon Tyne, UK
| | - Doug M Turnbull
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Newcastle upon Tyne, UK
| | - Robert W Taylor
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Newcastle upon Tyne, UK
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Lax NZ, Gorman GS, Turnbull DM. Review: Central nervous system involvement in mitochondrial disease. Neuropathol Appl Neurobiol 2016; 43:102-118. [PMID: 27287935 PMCID: PMC5363248 DOI: 10.1111/nan.12333] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2016] [Revised: 06/03/2016] [Accepted: 06/11/2016] [Indexed: 12/13/2022]
Abstract
Mitochondrial respiratory chain defects are an important cause of inherited disorders affecting approximately 1 in 5000 people in the UK population. Collectively these disorders are termed ‘mitochondrial diseases’ and they result from either mitochondrial DNA mutations or defects in nuclear DNA. Although they are frequently multisystem disorders, neurological deficits are particularly common, wide‐ranging and disabling for patients. This review details the manifold neurological impairments associated with mitochondrial disease, and describes the efforts to understand how they arise and progressively worsen in patients with mitochondrial disease. We describe advances in our understanding of disease pathogenesis through detailed neuropathological studies and how this has spurred the development of cellular and animal models of disease. We underscore the importance of continued clinical, molecular genetic, neuropathological and animal model studies to fully characterize mitochondrial diseases and understand mechanisms of neurodegeneration. These studies are instrumental for the next phase of mitochondrial research that has a particular emphasis on finding novel ways to treat mitochondrial disease to improve patient care and quality of life.
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Affiliation(s)
- N Z Lax
- The Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK
| | - G S Gorman
- The Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK
| | - D M Turnbull
- The Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK
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12
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Altmann J, Büchner B, Nadaj-Pakleza A, Schäfer J, Jackson S, Lehmann D, Deschauer M, Kopajtich R, Lautenschläger R, Kuhn KA, Karle K, Schöls L, Schulz JB, Weis J, Prokisch H, Kornblum C, Claeys KG, Klopstock T. Expanded phenotypic spectrum of the m.8344A>G "MERRF" mutation: data from the German mitoNET registry. J Neurol 2016; 263:961-972. [PMID: 26995359 DOI: 10.1007/s00415-016-8086-3] [Citation(s) in RCA: 61] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2015] [Revised: 02/28/2016] [Accepted: 02/29/2016] [Indexed: 11/24/2022]
Abstract
The m.8344A>G mutation in the MTTK gene, which encodes the mitochondrial transfer RNA for lysine, is traditionally associated with myoclonic epilepsy and ragged-red fibres (MERRF), a multisystemic mitochondrial disease that is characterised by myoclonus, seizures, cerebellar ataxia, and mitochondrial myopathy with ragged-red fibres. We studied the clinical and paraclinical phenotype of 34 patients with the m.8344A>G mutation, mainly derived from the nationwide mitoREGISTER, the multicentric registry of the German network for mitochondrial disorders (mitoNET). Mean age at symptom onset was 24.5 years ±10.9 (6-48 years) with adult onset in 75 % of the patients. In our cohort, the canonical features seizures, myoclonus, cerebellar ataxia and ragged-red fibres that are traditionally associated with MERRF, occurred in only 61, 59, 70, and 63 % of the patients, respectively. In contrast, other features such as hearing impairment were even more frequently present (72 %). Other common features in our cohort were migraine (52 %), psychiatric disorders (54 %), respiratory dysfunction (45 %), gastrointestinal symptoms (38 %), dysarthria (36 %), and dysphagia (35 %). Brain MRI revealed cerebral and/or cerebellar atrophy in 43 % of our patients. There was no correlation between the heteroplasmy level in blood and age at onset or clinical phenotype. Our findings further broaden the clinical spectrum of the m.8344A>G mutation, document the large clinical variability between carriers of the same mutation, even within families and indicate an overlap of the phenotype with other mitochondrial DNA-associated syndromes.
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Affiliation(s)
- Judith Altmann
- Department of Neurology, RWTH Aachen University, Aachen, Germany.,Institute of Neuropathology, RWTH Aachen University, Aachen, Germany
| | - Boriana Büchner
- Department of Neurology, Friedrich-Baur-Institute, Ludwig-Maximilians-University, München, Germany
| | | | - Jochen Schäfer
- Department of Neurology, University Hospital Carl Gustav Carus, Dresden, Germany
| | - Sandra Jackson
- Department of Neurology, University Hospital Carl Gustav Carus, Dresden, Germany
| | - Diana Lehmann
- Department of Neurology, University of Halle-Wittenberg, Halle/Saale, Germany
| | - Marcus Deschauer
- Department of Neurology, University of Halle-Wittenberg, Halle/Saale, Germany.,Department of Neurology, University of Technology München, München, Germany
| | - Robert Kopajtich
- Institute of Human Genetics, Helmholtz Centre München, München, Germany.,Institute of Human Genetics, Technical University München, München, Germany
| | - Ronald Lautenschläger
- Institute for Medical Statistics and Epidemiology, University of Technology München, München, Germany
| | - Klaus A Kuhn
- Institute for Medical Statistics and Epidemiology, University of Technology München, München, Germany
| | - Kathrin Karle
- Institute of Clinical Neurogenetics, Department of Neurology and Hertie Institute for Clinical Brain Research, Tübingen, Germany
| | - Ludger Schöls
- Institute of Clinical Neurogenetics, Department of Neurology and Hertie Institute for Clinical Brain Research, Tübingen, Germany
| | - Jörg B Schulz
- Department of Neurology, RWTH Aachen University, Aachen, Germany.,JARA - Translational Brain Medicine, Aachen, Germany
| | - Joachim Weis
- Institute of Neuropathology, RWTH Aachen University, Aachen, Germany
| | - Holger Prokisch
- Institute of Human Genetics, Helmholtz Centre München, München, Germany.,Institute of Human Genetics, Technical University München, München, Germany
| | - Cornelia Kornblum
- Department of Neurology, University Hospital of Bonn, Bonn, Germany.,Center for Rare Diseases Bonn (ZSEB), University Hospital of Bonn, Bonn, Germany
| | - Kristl G Claeys
- Department of Neurology, RWTH Aachen University, Aachen, Germany. .,Institute of Neuropathology, RWTH Aachen University, Aachen, Germany. .,Department of Neurology, University Hospitals Leuven and University of Leuven (KU Leuven), Leuven, Belgium.
| | - Thomas Klopstock
- Department of Neurology, Friedrich-Baur-Institute, Ludwig-Maximilians-University, München, Germany.,German Center for Neurodegenerative Diseases (DZNE), München, Germany.,Munich Cluster for Systems Neurology (SyNergy), München, Germany
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13
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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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Tzoulis C, Bindoff LA. Acute mitochondrial encephalopathy reflects neuronal energy failure irrespective of which genome the genetic defect affects. Brain 2012; 135:3627-34. [PMID: 23065482 DOI: 10.1093/brain/aws223] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Mitochondrial dysfunction and disease may arise as a result of mutations in either the mitochondrial genome itself or nuclear encoded genes involved in mitochondrial homeostasis and function. Irrespective of which genome is affected, mitochondrial encephalopathies share clinical and biochemical features suggesting common pathophysiological pathways. Two common paradigms of mitochondrial encephalopathy are mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes caused by maternally transmitted mutations of mitochondrial DNA and mitochondrial spinocerebellar ataxia and epilepsy caused by recessively inherited mutations of the nuclear-encoded DNA polymerase gamma, which replicates and repairs the mitochondrial genome. We studied and compared the disease mechanisms involved in these two syndromes. Despite having different genetic origins, their pathophysiological pathways converge on one critical event, damage to the respiratory chain leading to insufficient energy to maintain cellular homeostasis. In the central nervous system, this appears to cause selective neuronal damage leading to the development of lesions that mimic ischaemic damage, but which lack evidence of decreased tissue perfusion. Although these stroke-like lesions may expand or regress dynamically, the critical factor that dictates prognosis is the presence of epilepsy. Epileptic seizures increase the energy requirements of the metabolically already compromised neurons establishing a vicious cycle resulting in worsening energy failure and neuronal death. We believe that it is this cycle of events that determines outcome and which provides us with a mechanistic structure to understand the pathophysiology of acute mitochondrial encephalopathies and plan future treatments.
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Affiliation(s)
- Charalampos Tzoulis
- Department of Neurology, Haukeland University Hospital, 5021 Bergen, Norway.
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15
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Lax NZ, Pienaar IS, Reeve AK, Hepplewhite PD, Jaros E, Taylor RW, Kalaria RN, Turnbull DM. Microangiopathy in the cerebellum of patients with mitochondrial DNA disease. ACTA ACUST UNITED AC 2012; 135:1736-50. [PMID: 22577219 PMCID: PMC3359757 DOI: 10.1093/brain/aws110] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Neuropathological findings in mitochondrial DNA disease vary and are often dependent on the type of mitochondrial DNA defect. Many reports document neuronal cell loss, demyelination, gliosis and necrotic lesions in post-mortem material. However, previous studies highlight vascular abnormalities in patients harbouring mitochondrial DNA defects, particularly in those with the m.3243A>G mutation in whom stroke-like events are part of the mitochondrial encephalopathy lactic acidosis and stroke-like episodes syndrome. We investigated microangiopathic changes in the cerebellum of 16 genetically and clinically well-defined patients. Respiratory chain deficiency, high levels of mutated mitochondrial DNA and increased mitochondrial mass were present within the smooth muscle cells and endothelial cells comprising the vessel wall in patients. These changes were not limited to those harbouring the m.3243A>G mutation frequently associated with mitochondrial encephalopathy, lactic acidosis and stroke-like episodes, but were documented in patients harbouring m.8344A>G and autosomal recessive polymerase (DNA directed), gamma (POLG) mutations. In 8 of the 16 patients, multiple ischaemic-like lesions occurred in the cerebellar cortex suggestive of vascular smooth muscle cell dysfunction. Indeed, changes in vascular smooth muscle and endothelium distribution and cell size are indicative of vascular cell loss. We found evidence of blood–brain barrier breakdown characterized by plasma protein extravasation following fibrinogen and IgG immunohistochemistry. Reduced immunofluorescence was also observed using markers for endothelial tight junctions providing further evidence in support of blood–brain barrier breakdown. Understanding the structural and functional changes occurring in central nervous system microvessels in patients harbouring mitochondrial DNA defects will provide an important insight into mechanisms of neurodegeneration in mitochondrial DNA disease. Since therapeutic strategies targeting the central nervous system are limited, modulating vascular function presents an exciting opportunity to lessen the burden of disease in these patients.
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Affiliation(s)
- Nichola Z Lax
- The Wellcome Trust Centre for Mitochondrial Research, Institute for Ageing and Health, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
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Cerebellar ataxia in patients with mitochondrial DNA disease: a molecular clinicopathological study. J Neuropathol Exp Neurol 2012; 71:148-61. [PMID: 22249460 DOI: 10.1097/nen.0b013e318244477d] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Cerebellar ataxia is a prominent clinical symptom in patients with mitochondrial DNA (mtDNA) disease. This is often progressive with onset in young adulthood. We performed a detailed neuropathologic investigation of the olivary-cerebellum in 14 genetically and clinically well-defined patients with mtDNA disease. Quantitative neuropathologic investigation showed varying levels of loss of Purkinje cells and neurons of the dentate nucleus and inferior olivary nuclei. Typically, focal Purkinje cell loss was present in patients with the m.3243A>G mutation caused by the presence of microinfarcts, with relative preservation of neuronal cell populations in the olivary and dentate nuclei. In contrast, patients with the m.8344A>G mutation or recessive POLG mutations showed extensive and global neuronal cell loss in all 3 olivary-cerebellum areas examined. Molecular analysis of mutated mtDNA heteroplasmy levels revealed that neuronal cell loss occurred independently of the level of mutated mtDNA present within surviving neurons. High levels of neuronal respiratory chain deficiency, particularly of complex I, were detected in surviving cells; levels of deficiency were greater in regions with extensive cell loss. We found a relationship between respiratory deficiency and neuronal cell density, indicating that neuronal cell death correlates with respiratory deficiency. These findings highlight the vulnerability of the olivary-cerebellum to mtDNA defects.
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Tanji K. Morphological assessment of mitochondrial respiratory chain function on tissue sections. Methods Mol Biol 2012; 837:181-194. [PMID: 22215548 DOI: 10.1007/978-1-61779-504-6_12] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
In recent decades, genetic, biochemical, immunological, and cell biological techniques have been applied not only for better understanding of pathogenesis of known mitochondrial encephalomyopathies but also for exploring the possibility of mitochondrial involvement in other neurological, cardiac, gastrointestinal, and urological diseases. Techniques applied in a coordinated fashion have made it clear that mitochondrial dysfunction plays an important role in a wide range of human diseases including degenerative, toxic, metabolic, and neoplastic disorders. In this chapter, we provide updated protocols of essential histochemical and immunohistochemical methods that, in our opinion, are the most reliable morphological tool to visualize respiratory chain abnormality on tissue sections.
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Affiliation(s)
- Kurenai Tanji
- Neuromuscular Pathology Laboratory, Division of Neuropathology, Department of Pathology and Cell Biology, Columbia University, New York, NY, USA.
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18
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Martikainen MH, Majamaa K. Epidemiology and characteristics of occipital brain infarcts in young adults in southwestern Finland. J Neurol 2009; 257:259-63. [DOI: 10.1007/s00415-009-5305-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2009] [Revised: 08/06/2009] [Accepted: 08/18/2009] [Indexed: 11/25/2022]
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Amiot A, Tchikviladzé M, Joly F, Slama A, Hatem DC, Jardel C, Messing B, Lombès A. Frequency of mitochondrial defects in patients with chronic intestinal pseudo-obstruction. Gastroenterology 2009; 137:101-9. [PMID: 19344718 DOI: 10.1053/j.gastro.2009.03.054] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2008] [Revised: 03/04/2009] [Accepted: 03/23/2009] [Indexed: 01/29/2023]
Abstract
BACKGROUND & AIMS Chronic intestinal pseudo-obstruction (CIPO) is a rare disorder caused by intestinal dysmotility and characterized by chronic symptoms suggesting bowel obstruction in the absence of fixed, occluding lesions. CIPO has been associated with primary defects of the mitochondrial oxidative phosphorylation pathway, although the frequency of mitochondrial disorders in patients with CIPO is unknown. This study evaluates mitochondrial function in patients with CIPO. METHODS A retrospective study was performed of data collected from 80 CIPO patients at a tertiary centre over a 25-year period. Mitochondrial disorders were detected by analysis of serum lactate and thymidine phosphorylase activities, brain magnetic resonance images, and muscle biopsies. Genes encoding thymidine phosphorylase, mitochondrial DNA tRNA(leu(UUR)) or tRNA(lys), and DNA polymerase-gamma were analyzed for mutations. RESULTS Mitochondrial defects were identified in 15 patients (10 women; median age at diagnosis 32 years), representing 19% of the study cohort. All 15 patients had extra-digestive symptoms, 5 had mutations in the thymidine phosphorylase gene, 2 had mutations in tRNA(leu(UUR)), and 5 had mutations in the DNA polymerase-gamma gene. No genetic defect was detected in 3 of the patients with mitochondrial disorders. Patients with mitochondrial CIPO differed from patients without mitochondrial defects in their very severe nutritional status (frequent and long-term requirement for parenteral nutrition) and poor prognosis (frequent digestive and neurologic complications that led to a high incidence of premature death). CONCLUSION Mitochondrial disorders seem to be an important cause of CIPO. Patients with CIPO, especially severe cases with associated neurologic symptoms, should be tested for mitochondrial defects.
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Affiliation(s)
- Aurélien Amiot
- AP-HP, Hôpital Beaujon, Pôle des maladies de l'appareil digestif, Service de Gastroentérologie et d'assistance nutritive, Clichy, France
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20
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Zaganas I, Latsoudis H, Papadaki E, Vorgia P, Spilioti M, Plaitakis A. A8344G tRNALys mutation associated with recurrent brain stem stroke-like episodes. J Neurol 2009; 256:271-3. [PMID: 19253012 DOI: 10.1007/s00415-009-0921-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2007] [Revised: 01/21/2008] [Accepted: 02/15/2008] [Indexed: 11/26/2022]
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Tanji K, Bonilla E. Light microscopic methods to visualize mitochondria on tissue sections. Methods 2008; 46:274-80. [PMID: 18929660 DOI: 10.1016/j.ymeth.2008.09.027] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2008] [Revised: 09/29/2008] [Accepted: 09/30/2008] [Indexed: 11/25/2022] Open
Abstract
Mitochondria are cytoplasmic, double-membrane organelles, a main role of which is to synthesize ATP, the universal energy 'supply' of cells. In the last three decades, molecular genetic, biochemical, immunological and cell biological techniques have been applied in a coordinated fashion to unveil the pathogenesis of known mitochondrial disorders, as well as to explore the role of mitochondria in aging and neurodegenerative diseases. Once to be thought to be rare, it is now clear that mitochondrial dysfunction is an important cause of neurological and cardiac diseases, and age-related disorders such as cancer. Here, we review, illustrate, and provide updated protocols of two histochemical, and three immunohistochemical methods that in our opinion are the most reliable tools to visualize mitochondria on tissue sections from normal and disease specimens.
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Affiliation(s)
- Kurenai Tanji
- Department of Pathology, Columbia University, New York, NY 10032, USA
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22
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Unusual presentations of patients with the mitochondrial MERRF mutation A8344G. Clin Neurol Neurosurg 2008; 110:859-63. [DOI: 10.1016/j.clineuro.2008.06.010] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2008] [Revised: 06/17/2008] [Accepted: 06/18/2008] [Indexed: 11/21/2022]
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Tanji K, Kaufmann P, Naini AB, Lu J, Parsons TC, Wang D, Willey JZ, Shanske S, Hirano M, Bonilla E, Khandji A, Dimauro S, Rowland LP. A novel tRNA(Val) mitochondrial DNA mutation causing MELAS. J Neurol Sci 2008; 270:23-7. [PMID: 18314141 DOI: 10.1016/j.jns.2008.01.016] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2007] [Revised: 01/15/2008] [Accepted: 01/18/2008] [Indexed: 11/29/2022]
Abstract
Mitochondrial encephalopathy, lactic acidosis and stroke-like episodes (MELAS) is the most common mitochondrial disease due to mitochondrial DNA (mtDNA) mutations. At least 15 distinct mtDNA mutations have been associated with MELAS, and about 80% of the cases are caused by the A3243G tRNA(Leu(UUR)) gene mutation. We report here a novel tRNA(Val) mutation in a 37-year-old woman with manifestations of MELAS, and compare her clinicopathological phenotype with other rare cases associated tRNA(Val) mutations.
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Affiliation(s)
- Kurenai Tanji
- Department of Pathology, College of Physicians and Surgeons, Columbia University, New York, NY, USA.
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Tanji K, Bonilla E. Optical imaging techniques (histochemical, immunohistochemical, and in situ hybridization staining methods) to visualize mitochondria. Methods Cell Biol 2007; 80:135-54. [PMID: 17445692 DOI: 10.1016/s0091-679x(06)80006-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Affiliation(s)
- Kurenai Tanji
- Department of Pathology, Columbia University, New York, NY 10032, USA
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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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Joly F, Amiot A, Coffin B, Lavergne-Slove A, Messing B, Bouhnik Y. Pseudo-obstruction intestinale chronique. ACTA ACUST UNITED AC 2006; 30:975-85. [PMID: 17075444 DOI: 10.1016/s0399-8320(06)73359-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Chronic intestinal pseudo-obstruction (CIPO) is a disease characterized by episodes resembling mechanical obstruction in the absence of organic, systemic, or metabolic disorders. Pseudo-obstruction is an uncommon condition and can result from primary (40%) or secondary (60%) causes. The most common symptoms are nausea, vomiting, abdominal distension, abdominal pain and constipation or diarrhea. These symptoms are usually present many years before CIPO diagnosis. They can lead to severe electrolyte disorders and malnutrition. Principles for management of patients with CIPO are: to establish a correct clinical diagnosis in excluding mechanical obstruction; to perform a symptomatic and physiologic assessment of the gastrointestinal tract involved; to look for extra-intestinal manifestations, especially for myopathy and neuropathy; to discuss in some cases a surgery for full-thickness intestinal biopsies, and/or a neuromuscular biopsy in case of mitochondrial cytopathy suspicion. The management is primarily focused on symptom control and nutritional support to prevent weight loss and malnutrition. Treatment of CIPO includes prokinetic agents which may help to reduce gastrointestinal symptoms Courses of antibiotics may be needed in patients with symptoms suggestive of bacterial overgrowth. When necessary, enteral nutrition is preferred. In carefully selected patients, feeding jejunostomy with or without decompression gastrostomy may be tried. Long term parenteral nutrition should be reserved for patients who can not tolerate enteral nutrition. Intestinal transplantation can be discussed in selected patients.
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Affiliation(s)
- Francisca Joly
- Service de Gastroentérologie et d'Assistance nutritive, Hôpital Beaujon, 100 Boulevard du Général Leclerc, Clichy-la-Garenne, 92110 Clichy cedex
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Naini A, Kaufmann P, Shanske S, Engelstad K, De Vivo DC, Schon EA. Hypocitrullinemia in patients with MELAS: an insight into the “MELAS paradox”. J Neurol Sci 2005; 229-230:187-93. [PMID: 15760638 DOI: 10.1016/j.jns.2004.11.026] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
L-citrulline, classified as a nonessential amino acid, is synthesized predominantly via Delta-1-pyrroline carboxylate synthase in the endothelial cells of the small intestine. In mammals, small quantities of citrulline are also produced in nitric oxide synthase-expressing cells. Considering the fact that the enzymes involved in the endogenous synthesis of L-citrulline are all located in the mitochondria and the fact that citrulline is a component of the citrulline-nitric oxide (NO) cycle, we hypothesized that the distinct clinical, biochemical, and morphological characteristics of MELAS, a maternally inherited mitochondrial disorder, might be due to alterations in nitric oxide homeostasis. Analysis of serum from MELAS patients showed that levels of plasma arginine were similar in both patients and in controls. However, levels of citrulline in MELAS patients were significantly lower than in controls, and there was a clear inverse correlation between arginine and citrulline levels in these patients. We found no correlation between the level of heteroplasmy and the plasma levels of either arginine or citrulline. We discuss the depressed citrulline levels in MELAS patients, who have an unusual and paradoxical pattern of vascular respiratory chain expression, in the context of NO homeostasis.
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Affiliation(s)
- Ali Naini
- Department of Neurology, Columbia University College of Physicians and Surgeons, New York, NY 10032, USA
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