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Armirola-Ricaurte C, Morant L, Adant I, Hamed SA, Pipis M, Efthymiou S, Amor-Barris S, Atkinson D, Van de Vondel L, Tomic A, de Vriendt E, Zuchner S, Ghesquiere B, Hanna M, Houlden H, Lunn MP, Reilly MM, Rasic VM, Jordanova A. Biallelic variants in COX18 cause a mitochondrial disorder primarily manifesting as peripheral neuropathy. MEDRXIV : THE PREPRINT SERVER FOR HEALTH SCIENCES 2024:2024.07.03.24309787. [PMID: 39006432 PMCID: PMC11245062 DOI: 10.1101/2024.07.03.24309787] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/16/2024]
Abstract
Defects in mitochondrial dynamics are a common cause of Charcot-Marie-Tooth disease (CMT), while primary deficiencies in the mitochondrial respiratory chain (MRC) are rare and atypical for this etiology. This study aims to report COX18 as a novel CMT-causing gene. This gene encodes an assembly factor of mitochondrial Complex IV (CIV) that translocates the C-terminal tail of MTCO2 across the mitochondrial inner membrane. Exome sequencing was performed in four affected individuals. The patients and available family members underwent thorough neurological and electrophysiological assessment. The impact of one of the identified variants on splicing, protein levels, and mitochondrial bioenergetics was investigated in patient-derived lymphoblasts. The functionality of the mutant protein was assessed using a Proteinase K protection assay and immunoblotting. Neuronal relevance of COX18 was assessed in a Drosophila melanogaster knockdown model. Exome sequencing coupled with homozygosity mapping revealed a homozygous splice variant c.435-6A>G in COX18 in two siblings with early-onset progressive axonal sensory-motor peripheral neuropathy. By querying external databases, we identified two additional families with rare deleterious biallelic variants in COX18 . All affected individuals presented with axonal CMT and some patients also exhibited central nervous system symptoms, such as dystonia and spasticity. Functional characterization of the c.435-6A>G variant demonstrated that it leads to the expression of an alternative transcript that lacks exon 2, resulting in a stable but defective COX18 isoform. The mutant protein impairs CIV assembly and activity, leading to a reduction in mitochondrial membrane potential. Downregulation of the COX18 homolog in Drosophila melanogaster displayed signs of neurodegeneration, including locomotor deficit and progressive axonal degeneration of sensory neurons. Our study presents genetic and functional evidence that supports COX18 as a newly identified gene candidate for autosomal recessive axonal CMT with or without central nervous system involvement. These findings emphasize the significance of peripheral neuropathy within the spectrum of primary mitochondrial disorders and the role of mitochondrial CIV in the development of CMT. Our research has important implications for the diagnostic workup of CMT patients.
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Armirola-Ricaurte C, Zonnekein N, Koutsis G, Amor-Barris S, Pelayo-Negro AL, Atkinson D, Efthymiou S, Turchetti V, Dinopoulos A, Garcia A, Karakaya M, Moris G, Polat AI, Yiş U, Espinos C, Van de Vondel L, De Vriendt E, Karadima G, Wirth B, Hanna M, Houlden H, Berciano J, Jordanova A. Alternative splicing expands the clinical spectrum of NDUFS6-related mitochondrial disorders. Genet Med 2024; 26:101117. [PMID: 38459834 PMCID: PMC11180951 DOI: 10.1016/j.gim.2024.101117] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Revised: 03/03/2024] [Accepted: 03/04/2024] [Indexed: 03/10/2024] Open
Abstract
PURPOSE We describe 3 families with Charcot-Marie-Tooth neuropathy (CMT), harboring a homozygous NDUFS6 NM_004553.6:c.309+5G>A variant previously linked to fatal Leigh syndrome. We aimed to characterize clinically and molecularly the newly identified patients and understand the mechanism underlying their milder phenotype. METHODS The patients underwent extensive clinical examinations. Exome sequencing was done in 4 affected individuals. The functional effect of the c.309+5G>A variant was investigated in patient-derived EBV-transformed lymphoblasts at the complementary DNA, protein, and mitochondrial level. Alternative splicing was evaluated using complementary DNA long-read sequencing. RESULTS All patients presented with early-onset, slowly progressive axonal CMT, and nystagmus; some exhibited additional central nervous system symptoms. The c.309+5G>A substitution caused the expression of aberrantly spliced transcripts and negligible levels of the canonical transcript. Immunoblotting showed reduced levels of mutant isoforms. No detectable defects in mitochondrial complex stability or bioenergetics were found. CONCLUSION We expand the clinical spectrum of NDUFS6-related mitochondrial disorders to include axonal CMT, emphasizing the clinical and pathophysiologic overlap between these 2 clinical entities. This work demonstrates the critical role that alternative splicing may play in modulating the severity of a genetic disorder, emphasizing the need for careful consideration when interpreting splice variants and their implications on disease prognosis.
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Affiliation(s)
- Camila Armirola-Ricaurte
- Molecular Neurogenomics group, VIB Center for Molecular Neurology, VIB, Antwerp, Belgium; Molecular Neurogenomics group, Department of Biomedical Sciences, University of Antwerp, Antwerp, Belgium
| | - Noortje Zonnekein
- Molecular Neurogenomics group, VIB Center for Molecular Neurology, VIB, Antwerp, Belgium; Molecular Neurogenomics group, Department of Biomedical Sciences, University of Antwerp, Antwerp, Belgium
| | - Georgios Koutsis
- Neurogenetics Unit, 1st Department of Neurology, Eginitio Hospital, Medical School, National and Kapodistrian University of Athens, Athens, Greece
| | - Silvia Amor-Barris
- Molecular Neurogenomics group, VIB Center for Molecular Neurology, VIB, Antwerp, Belgium; Molecular Neurogenomics group, Department of Biomedical Sciences, University of Antwerp, Antwerp, Belgium
| | - Ana Lara Pelayo-Negro
- University Hospital Marqués de Valdecilla (IFIMAV), University of Cantabria, Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), Santander, Spain
| | - Derek Atkinson
- Molecular Neurogenomics group, VIB Center for Molecular Neurology, VIB, Antwerp, Belgium; Molecular Neurogenomics group, Department of Biomedical Sciences, University of Antwerp, Antwerp, Belgium
| | - Stephanie Efthymiou
- Department of Neuromuscular Disorders, UCL Institute of Neurology, Queen Square, London, United Kingdom
| | - Valentina Turchetti
- Department of Neuromuscular Disorders, UCL Institute of Neurology, Queen Square, London, United Kingdom
| | - Argyris Dinopoulos
- 3rd Department of Pediatrics, Attiko Hospital, Medical School, National and Kapodistrian University of Athens, Athens, Greece
| | - Antonio Garcia
- Service of Clinical Neurophysiology, University Hospital Marqués de Valdecilla, Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), Santander, Spain
| | - Mert Karakaya
- Institute of Human Genetics, Center for Molecular Medicine Cologne, Center for Rare Diseases, University Hospital of Cologne, University of Cologne, Cologne, Germany
| | - German Moris
- Service of Neurology, University Hospital Central de Asturias, University of Oviedo, Oviedo, Spain
| | - Ayşe Ipek Polat
- Department of Pediatric Neurology, Dokuz Eylül University, Izmir, Turkey
| | - Uluç Yiş
- Department of Pediatric Neurology, Dokuz Eylül University, Izmir, Turkey
| | - Carmen Espinos
- Rare Neurodegenerative Disease Laboratory, Centro de Investigación Príncipe Felipe (CIPF), CIBER on Rare Diseases (CIBERER), Valencia, Spain
| | - Liedewei Van de Vondel
- Translational Neurosciences, Faculty of Medicine and Health Sciences, University of Antwerp, Antwerp, Belgium; Laboratory of Neuromuscular Pathology, Institute Born-Bunge, University of Antwerp, Antwerp, Belgium
| | - Els De Vriendt
- Molecular Neurogenomics group, VIB Center for Molecular Neurology, VIB, Antwerp, Belgium; Molecular Neurogenomics group, Department of Biomedical Sciences, University of Antwerp, Antwerp, Belgium
| | - Georgia Karadima
- Neurogenetics Unit, 1st Department of Neurology, Eginitio Hospital, Medical School, National and Kapodistrian University of Athens, Athens, Greece
| | - Brunhilde Wirth
- Institute of Human Genetics, Center for Molecular Medicine Cologne, Center for Rare Diseases, University Hospital of Cologne, University of Cologne, Cologne, Germany
| | - Michael Hanna
- Department of Neuromuscular Disorders, UCL Institute of Neurology, Queen Square, London, United Kingdom
| | - Henry Houlden
- Department of Neuromuscular Disorders, UCL Institute of Neurology, Queen Square, London, United Kingdom
| | - Jose Berciano
- University Hospital Marqués de Valdecilla (IFIMAV), University of Cantabria, Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), Santander, Spain
| | - Albena Jordanova
- Molecular Neurogenomics group, VIB Center for Molecular Neurology, VIB, Antwerp, Belgium; Molecular Neurogenomics group, Department of Biomedical Sciences, University of Antwerp, Antwerp, Belgium; Department of Medical Chemistry and Biochemistry, Medical University-Sofia, Sofia, Bulgaria.
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Beecher G, Gavrilova RH, Mandrekar J, Naddaf E. Mitochondrial myopathies diagnosed in adulthood: clinico-genetic spectrum and long-term outcomes. Brain Commun 2024; 6:fcae041. [PMID: 38434220 PMCID: PMC10906953 DOI: 10.1093/braincomms/fcae041] [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: 09/04/2023] [Revised: 12/14/2023] [Accepted: 02/12/2024] [Indexed: 03/05/2024] Open
Abstract
Mitochondrial myopathies are frequently recognized in childhood as part of a broader multisystem disorder and often overlooked in adulthood. Herein, we describe the phenotypic and genotypic spectrum and long-term outcomes of mitochondrial myopathies diagnosed in adulthood, focusing on neuromuscular features, electrodiagnostic and myopathological findings and survival. We performed a retrospective chart review of adult patients diagnosed with mitochondrial myopathy at Mayo Clinic (2005-21). We identified 94 patients. Median time from symptom onset to diagnosis was 11 years (interquartile range 4-21 years). Median age at diagnosis was 48 years (32-63 years). Primary genetic defects were identified in mitochondrial DNA in 48 patients (10 with single large deletion, 38 with point mutations) and nuclear DNA in 29. Five patients had multiple mitochondrial DNA deletions or depletion without nuclear DNA variants. Twelve patients had histopathological features of mitochondrial myopathy without molecular diagnosis. The most common phenotypes included multisystem disorder (n = 30); mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes (14); limb myopathy (13); chronic progressive external ophthalmoplegia (12); and chronic progressive external ophthalmoplegia-plus (12). Isolated skeletal muscle manifestations occurred in 27%. Sixty-nine per cent had CNS and 21% had cardiac involvement. Mutations most frequently involved MT-TL1 (27) and POLG (17); however, a wide spectrum of established and novel molecular defects, with overlapping phenotypes, was identified. Electrodiagnostic studies identified myopathy (77%), fibrillation potentials (27%) and axonal peripheral neuropathy (42%, most common with nuclear DNA variants). Among 42 muscle biopsies available, median percentage counts were highest for cytochrome C oxidase negative fibres (5.1%) then ragged blue (1.4%) and ragged red fibres (0.5%). Skeletal muscle weakness was mild and slowly progressive (decline in strength summated score of 0.01/year). Median time to gait assistance was 5.5 years from diagnosis and 17 years from symptom onset. Thirty patients died, with median survival of 33.4 years from symptom onset and 10.9 years from diagnosis. Median age at death was 55 years. Cardiac involvement was associated with increased mortality [hazard ratio 2.36 (1.05, 5.29)]. There was no difference in survival based on genotype or phenotype. Despite the wide phenotypic and genotypic spectrum, mitochondrial myopathies in adults share similar features with slowly progressive limb weakness, contrasting with common multiorgan involvement and high mortality.
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Affiliation(s)
- Grayson Beecher
- Department of Neurology, Mayo Clinic, Rochester, MN 55905, USA
- Division of Neurology, Department of Medicine, University of Alberta, Edmonton, Alberta, Canada T6G 2G3
| | - Ralitza H Gavrilova
- Department of Neurology, Mayo Clinic, Rochester, MN 55905, USA
- Department of Clinical Genomics, Mayo Clinic, Rochester, MN 55905, USA
| | - Jay Mandrekar
- Department of Neurology, Mayo Clinic, Rochester, MN 55905, USA
| | - Elie Naddaf
- Department of Neurology, Mayo Clinic, Rochester, MN 55905, USA
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Ratia N, Palu E, Lantto H, Ylikallio E, Luukkonen R, Suomalainen A, Auranen M, Piirilä P. Lowered oxidative capacity in spinal muscular atrophy, Jokela type; comparison with mitochondrial muscle disease. Front Neurol 2023; 14:1277944. [PMID: 38020590 PMCID: PMC10663357 DOI: 10.3389/fneur.2023.1277944] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2023] [Accepted: 10/23/2023] [Indexed: 12/01/2023] Open
Abstract
Introduction Spinal muscular atrophy, Jokela type (SMAJ) is a rare autosomal dominantly hereditary form of spinal muscular atrophy caused by a point mutation c.197G>T in CHCHD10. CHCHD10 is known to be involved in the regulation of mitochondrial function even though patients with SMAJ do not present with multiorgan symptoms of mitochondrial disease. We aimed to characterize the cardiopulmonary oxidative capacity of subjects with SMAJ compared to healthy controls and patients with mitochondrial myopathy. Methods Eleven patients with genetically verified SMAJ, 26 subjects with mitochondrial myopathy (MM), and 28 healthy volunteers underwent a cardiopulmonary exercise test with lactate and ammonia sampling. The effect of the diagnosis group on the test results was analysed using a linear model. Results Adjusted for sex, age, and BMI, the SMAJ group had lower power output (p < 0.001), maximal oxygen consumption (VO2 max) (p < 0.001), and mechanical efficiency (p < 0.001) compared to the healthy controls but like that in MM. In the SMAJ group and healthy controls, plasma lactate was lower than in MM measured at rest, light exercise, and 30 min after exercise (p ≤ 0.001-0.030) and otherwise lactate in SMAJ was lower than controls and MM, in longitudinal analysis p = 0.018. In MM, the ventilatory equivalent for oxygen was higher (p = 0.040), and the fraction of end-tidal CO2 lower in maximal exercise compared to healthy controls (p = 0.023) and subjects with SMAJ. Conclusion In cardiopulmonary exercise test, subjects with SMAJ showed a similar decrease in power output and oxidative capacity as subjects with mitochondrial myopathy but did not exhibit findings typical of mitochondrial disease.
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Affiliation(s)
- Nadja Ratia
- Unit of Clinical Physiology, HUS Medical Diagnosis Center, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
| | - Edouard Palu
- Unit of Neurophysiology, HUS Medical Diagnosis Center, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
| | - Hanna Lantto
- Unit of Clinical Physiology, HUS Medical Diagnosis Center, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
| | - Emil Ylikallio
- Clinical Neurosciences, Neurology, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
- Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | | | - Anu Suomalainen
- Clinical Neurosciences, Neurology, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
- Research Program of Stem Cells and Metabolism, Faculty of Medicine, University of Helsinki, Helsinki, Finland
- Neuroscience Center, HiLife, University of Helsinki, Helsinki, Finland
| | - Mari Auranen
- Clinical Neurosciences, Neurology, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
| | - Päivi Piirilä
- Unit of Clinical Physiology, HUS Medical Diagnosis Center, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
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Lu JQ, Tarnopolsky MA. Mitochondrial neuropathy and neurogenic features in mitochondrial myopathy. Mitochondrion 2020; 56:52-61. [PMID: 33220502 DOI: 10.1016/j.mito.2020.11.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Revised: 10/25/2020] [Accepted: 11/02/2020] [Indexed: 01/21/2023]
Abstract
Mitochondrial diseases (MIDs) involve multiple organs including peripheral nerves and skeletal muscle. Mitochondrial neuropathy (MN) and mitochondrial myopathy (MM) are commonly associated and linked at the neuromuscular junction (NMJ). Herein we review MN in connection with neurogenic features of MM, and pathological evidence for the involvement of the peripheral nerve and NMJ in MID patients traditionally assumed to have predominantly MM. MN is not uncommon, but still likely under-reported, and muscle biopsies of MM commonly exhibit neurogenic features. Pathological examination remains the gold standard to assess the nerve and muscle changes in patients with MIDs. Ultrastructural studies by electron microscopy are often necessary to fully characterize the pathology of mitochondrial cytopathy in MN and MM.
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Affiliation(s)
- Jian-Qiang Lu
- Department of Pathology and Molecular Medicine/Neuropathology, McMaster University, Hamilton, Ontario, Canada.
| | - Mark A Tarnopolsky
- Department of Medicine/Neurology, McMaster University, Hamilton, Ontario, Canada; Department of Pediatrics, McMaster University, Hamilton, Ontario, Canada
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Lu JQ, Mubaraki A, Yan C, Provias J, Tarnopolsky MA. Neurogenic Muscle Biopsy Findings Are Common in Mitochondrial Myopathy. J Neuropathol Exp Neurol 2019; 78:508-514. [DOI: 10.1093/jnen/nlz029] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Affiliation(s)
- Jian-Qiang Lu
- Department of Pathology and Molecular Medicine/Neuropathology
| | | | - Chuanzhu Yan
- Department of Pediatrics, McMaster University, Hamilton, Ontario, Canada
- Neuromuscular Center; and Mitochondrial Medicine Laboratory, Qilu Hospital, Shandong University, Shandong, China
| | - John Provias
- Department of Pathology and Molecular Medicine/Neuropathology
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Poulsen NS, Dahlqvist JR, Hedermann G, Løkken N, Vissing J. Muscle contractility of leg muscles in patients with mitochondrial myopathies. Mitochondrion 2018; 46:221-227. [PMID: 30017555 DOI: 10.1016/j.mito.2018.07.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Revised: 05/24/2018] [Accepted: 07/05/2018] [Indexed: 11/25/2022]
Abstract
BACKGROUND The primary disease mechanism underlying mitochondrial myopathies (MM) is impaired energy generation to support muscle endurance. Little is known about muscle contractility before energy becomes deficient during muscle contractions. We investigated muscle contractility in MM to uncover potentially fixed weakness aspects of the disorders. METHODS Contractility of calf and thigh muscles was investigated by comparing strength with contractile cross-sectional area (CCSA) of the used muscles, as measured by stationary dynamometry and MRI, respectively. RESULTS AND DISCUSSION Our findings suggest reduced contractile properties in thigh and calf muscles of patients with MM.
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Affiliation(s)
- Nanna Scharff Poulsen
- Copenhagen Neuromuscular Center, Rigshospitalet, Copenhagen University Hospital, 2100 Copenhagen, Denmark.
| | - Julia Rebecka Dahlqvist
- Copenhagen Neuromuscular Center, Rigshospitalet, Copenhagen University Hospital, 2100 Copenhagen, Denmark
| | - Gitte Hedermann
- Copenhagen Neuromuscular Center, Rigshospitalet, Copenhagen University Hospital, 2100 Copenhagen, Denmark
| | - Nicoline Løkken
- Copenhagen Neuromuscular Center, Rigshospitalet, Copenhagen University Hospital, 2100 Copenhagen, Denmark
| | - John Vissing
- Copenhagen Neuromuscular Center, Rigshospitalet, Copenhagen University Hospital, 2100 Copenhagen, Denmark
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Samuelsson K, Mariosa D, Fang F, Press R. Comorbidity of mitochondrial disease and dementia in patients with idiopathic polyneuropathy. Eur J Neurol 2018; 25:882-887. [DOI: 10.1111/ene.13612] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2017] [Accepted: 02/28/2018] [Indexed: 12/17/2022]
Affiliation(s)
- K. Samuelsson
- Department of Clinical Neuroscience; Karolinska Institutet; Stockholm
- Department of Neurology; Karolinska University Hospital; Stockholm
| | - D. Mariosa
- Department of Medical Epidemiology and Biostatistics; Karolinska Institutet; Stockholm Sweden
| | - F. Fang
- Department of Medical Epidemiology and Biostatistics; Karolinska Institutet; Stockholm Sweden
| | - R. Press
- Department of Clinical Neuroscience; Karolinska Institutet; Stockholm
- Department of Neurology; Karolinska University Hospital; Stockholm
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Patient care standards for primary mitochondrial disease: a consensus statement from the Mitochondrial Medicine Society. Genet Med 2017; 19:S1098-3600(21)04766-3. [PMID: 28749475 DOI: 10.1038/gim.2017.107] [Citation(s) in RCA: 153] [Impact Index Per Article: 21.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Accepted: 05/25/2017] [Indexed: 02/07/2023] Open
Abstract
The purpose of this statement is to provide consensus-based recommendations for optimal management and care for patients with primary mitochondrial disease. This statement is intended for physicians who are engaged in the diagnosis and management of these patients. Working group members were appointed by the Mitochondrial Medicine Society. The panel included members with several different areas of expertise. The panel members utilized surveys and the Delphi method to reach consensus. We anticipate that this statement will need to be updated as the field continues to evolve. Consensus-based recommendations are provided for the routine care and management of patients with primary genetic mitochondrial disease.
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"Mitochondrial neuropathies": A survey from the large cohort of the Italian Network. Neuromuscul Disord 2016; 26:272-6. [PMID: 27020842 DOI: 10.1016/j.nmd.2016.02.008] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2015] [Revised: 02/10/2016] [Accepted: 02/15/2016] [Indexed: 11/21/2022]
Abstract
Involvement of the peripheral nervous system in mitochondrial disorders has been previously reported. However, the prevalence of peripheral neuropathy in mitochondrial disorders is still unclear. Based on the large database of the "Nation-wide Italian Collaborative Network of Mitochondrial Diseases", we reviewed the clinical data of 1200 patients, with special regard to peripheral neuropathy (mean age at onset 24.3 ± 20.1 years; age at last evaluation 39.8 ± 22.3 years; females 52.7%; childhood onset [before age 16 years] 43.1%). Peripheral neuropathy was present in 143/1156 patients (12.4%), being one of the ten most common signs and symptoms. POLG mutations cause a potentially painful, axonal/mixed, mainly sensory polyneuropathy; TYMP mutations lead to a demyelinating sensory-motor polyneuropathy; SURF1 mutations are associated with a demyelinating/mixed sensory-motor polyneuropathy. The only mtDNA mutation consistently associated with peripheral neuropathy (although less severely than in the above-considered nuclear genes) was the m.8993T > G (or the rarer T > C) changes, which lead to an axonal, mainly sensory polyneuropathy. In conclusion, peripheral neuropathy is one of the most common features of a mitochondrial disorder, and may negatively impact on the quality of life of these patients. Furthermore, the presence or absence of peripheral neuropathy, as well as its specific forms and the association with neuropathic pain (indicative of a POLG-associated disease) can guide the molecular analysis.
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11
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The potential and limitations of quantitative electromyography in equine medicine. Vet J 2015; 209:23-31. [PMID: 26831156 DOI: 10.1016/j.tvjl.2015.07.024] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2015] [Revised: 07/20/2015] [Accepted: 07/21/2015] [Indexed: 11/21/2022]
Abstract
This review discusses the scope of using (quantitative) electromyography (EMG) in diagnosing myopathies and neuropathies in equine patients. In human medicine, many EMG methods are available for the diagnosis, pathophysiological description and evaluation, monitoring, or rehabilitation of patients, and some of these techniques have also been applied to horses. EMG results are usually combined with other neurophysiological data, ultrasound, histochemistry, biochemistry of muscle biopsies, and clinical signs in order to provide a complete picture of the condition and its clinical course. EMG technology is commonly used in human medicine and has been subject to constant development and refinement since its introduction in 1929, but the usefulness of the technique in equine medicine is not yet widely acknowledged. The possibilities and limitations of some EMG applications for equine use are discussed.
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12
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Millichap JG, Millichap JJ. Electromyography and Metabolic Myopathies. Pediatr Neurol Briefs 2014. [DOI: 10.15844/pedneurbriefs-28-9-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
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13
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Samuelsson K, Kostulas K, Vrethem M, Rolfs A, Press R. Idiopathic small fiber neuropathy: phenotype, etiologies, and the search for fabry disease. J Clin Neurol 2014; 10:108-18. [PMID: 24829596 PMCID: PMC4017013 DOI: 10.3988/jcn.2014.10.2.108] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2013] [Revised: 10/25/2013] [Accepted: 10/28/2013] [Indexed: 12/15/2022] Open
Abstract
Background and Purpose The etiology of small fiber neuropathy (SFN) often remains unclear. Since SFN may be the only symptom of late-onset Fabry disease, it may be underdiagnosed in patients with idiopathic polyneuropathy. We aimed to uncover the etiological causes of seemingly idiopathic SFN by applying a focused investigatory procedure, to describe the clinical phenotype of true idiopathic SFN, and to elucidate the possible prevalence of late-onset Fabry disease in these patients. Methods Forty-seven adults younger than 60 years with seemingly idiopathic pure or predominantly small fiber sensory neuropathy underwent a standardized focused etiological and clinical investigation. The patients deemed to have true idiopathic SFN underwent genetic analysis of the alpha-galactosidase A gene (GLA) that encodes the enzyme alpha-galactosidase A (Fabry disease). Results The following etiologies were identified in 12 patients: impaired glucose tolerance (58.3%), diabetes mellitus (16.6%), alcohol abuse (8.3%), mitochondrial disease (8.3%), and hereditary neuropathy (8.3%). Genetic alterations of unknown clinical significance in GLA were detected in 6 of the 29 patients with true idiopathic SFN, but this rate did not differ significantly from that in healthy controls (n=203). None of the patients with genetic alterations in GLA had significant biochemical abnormalities simultaneously in blood, urine, and skin tissue. Conclusions A focused investigation may aid in uncovering further etiological factors in patients with seemingly idiopathic SFN, such as impaired glucose tolerance. However, idiopathic SFN in young to middle-aged Swedish patients does not seem to be due to late-onset Fabry disease.
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Affiliation(s)
- Kristin Samuelsson
- Department of Neurology, Department of Clinical Neuroscience, Karolinska Institutet, Karolinska University Hospital Huddinge, Stockholm, Sweden
| | - Konstantinos Kostulas
- Department of Neurology, Department of Clinical Neuroscience, Karolinska Institutet, Karolinska University Hospital Huddinge, Stockholm, Sweden
| | - Magnus Vrethem
- Division of Neurology and Clinical Neurophysiology, Department of Clinical and Experimental Medicine, Faculty of Health Sciences, Linköping University, Linköping, Sweden
| | - Arndt Rolfs
- Albrecht-Kossel Institute for Neuroregeneration, University of Rostock, Rostock, Germany
| | - Rayomand Press
- Department of Neurology, Department of Clinical Neuroscience, Karolinska Institutet, Karolinska University Hospital Huddinge, Stockholm, Sweden
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Abstract
Diseases of muscle may be congenital or acquired. They cause muscle weakness without sensory loss. The onset, distribution, and clinical course help to differentiate the type of muscle disorder. The diagnostic workup may include laboratory examination, electrodiagnostic studies, and muscle biopsy. A definitive diagnosis leads to better decision making with regard to treatment, genetic education, prognosis, functional expectations, and the impact of exercise on muscle function.
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Affiliation(s)
- Anthony Chiodo
- Physical Medicine and Rehabilitation, University of Michigan Hospital, 325 E Eisenhower Parkway, Ann Arbor, MI 48118, USA.
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