1
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Dupré M, Warne R, Shipman P, Kava M, Ghia T, Loughman L, Lakshmanan R. Cranial and spinal nerve enhancement in SURF1-associated Leigh syndrome. Pediatr Radiol 2024; 54:1758-1762. [PMID: 39066889 PMCID: PMC11377472 DOI: 10.1007/s00247-024-06005-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/26/2024] [Revised: 07/11/2024] [Accepted: 07/11/2024] [Indexed: 07/30/2024]
Abstract
A 23-month-old boy with poor growth, developmental delay, and hypotonia presented with acute onset of ataxia and fatigue. Magnetic resonance imaging (MRI) of the brain and spinal cord was performed as part of diagnostic work-up. MRI showed bilateral symmetrical lesions in basal ganglia, midbrain, and brainstem consistent with Leigh syndrome. Signal abnormalities were also present within the cervical cord, with enhancement of multiple cranial, spinal, and cauda equina nerve roots. Genetic testing confirmed compound heterozygosity for two pathogenic variants in SURF1 implicated in Leigh syndrome. Whilst nerve root enhancement has been described in other mitochondrial disorders, we believe this is the first published case of both cranial and spinal nerve root enhancement in Leigh syndrome.
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Affiliation(s)
- Mhairi Dupré
- Medical Imaging Department, Perth Children's Hospital, Perth, 6009, Australia
| | - Richard Warne
- Medical Imaging Department, Perth Children's Hospital, Perth, 6009, Australia
| | - Peter Shipman
- Medical Imaging Department, Perth Children's Hospital, Perth, 6009, Australia
| | - Maina Kava
- Department of Neurology, Perth Children's Hospital, Perth, 6009, Australia
- Department of Metabolic Medicine, Perth Children's Hospital, Perth, 6009, Australia
- School of Paediatrics and Child Health, UWA Medical School, University of Western Australia, Perth, 6009, Australia
| | - Twinkle Ghia
- Department of Neurology, Perth Children's Hospital, Perth, 6009, Australia
| | - Lily Loughman
- Genetic Health Western Australia, King Edward Memorial Hospital, Perth, 6008, Australia
| | - Rahul Lakshmanan
- Medical Imaging Department, Perth Children's Hospital, Perth, 6009, Australia.
- UWA Medical School, Centre for Neuromuscular and Neurological Disorders (Perron Institute), Nedlands, 6009, Australia.
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2
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Gangfuß A, Rating P, Ferreira T, Hentschel A, Marina AD, Kölbel H, Sickmann A, Abicht A, Kraft F, Ruck T, Böhm J, Schänzer A, Schara-Schmidt U, Neuhann TM, Horvath R, Roos A. A Homozygous NDUFS6 Variant Associated with Neuropathy and Optic Atrophy. J Neuromuscul Dis 2024; 11:485-491. [PMID: 38217609 DOI: 10.3233/jnd-230181] [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] [Indexed: 01/15/2024]
Abstract
Background The NADH dehydrogenase [ubiquinone] iron-sulfur protein 6 (NDUFS6) gene encodes for an accessory subunit of the mitochondrial membrane respiratory chain NADH dehydrogenase (complex I). Bi-allelic NDUFS6 variants have been linked with a severe disorder mostly reported as a lethal infantile mitochondrial disease (LMID) or Leigh syndrome (LS). Objective Here, we identified a homozygous variant (c.309 + 5 G > A) in NDUFS6 in one male patient with axonal neuropathy accompanied by loss of small fibers in skin biopsy and further complicated by optic atrophy and borderline intellectual disability. Methods To address the pathogenicity of the variant, biochemical studies (mtDNA copy number quantification, ELISA, Proteomic profiling) of patient-derived leukocytes were performed. Results The analyses revealed loss of NDUFS6 protein associated with a decrease of three further mitochondrial NADH dehydrogenase subunit/assembly proteins (NDUFA12, NDUFS4 and NDUFV1). Mitochondrial copy number is not altered in leukocytes and the mitochondrial biomarker GDF15 is not significantly changed in serum. Conclusions Hence, our combined clinical and biochemical data strengthen the concept of NDUFS6 being causative for a very rare form of axonal neuropathy associated with optic atrophy and borderline intellectual disability, and thus expand (i) the molecular genetic landscape of neuropathies and (ii) the clinical spectrum of NDUFS6-associated phenotypes.
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Affiliation(s)
- Andrea Gangfuß
- Department of Pediatric Neurology, Centre for Neuromuscular Disorders, Centre for Translational Neuro- and Behavioral Sciences, University Duisburg-Essen, Essen, Germany
| | - Philipp Rating
- Department of Ophthalmology, University Duisburg-Essen, Essen, Germany
| | - Tomas Ferreira
- Department of Clinical Neurosciences, John Van Geest Centre for Brain Repair, School of Clinical Medicine, University of Cambridge, Cambridge, UK
| | - Andreas Hentschel
- Leibniz-Institut für Analytische Wissenschaften - ISAS - e.V. Dortmund, Germany
| | - Adela Della Marina
- Department of Pediatric Neurology, Centre for Neuromuscular Disorders, Centre for Translational Neuro- and Behavioral Sciences, University Duisburg-Essen, Essen, Germany
| | - Heike Kölbel
- Department of Pediatric Neurology, Centre for Neuromuscular Disorders, Centre for Translational Neuro- and Behavioral Sciences, University Duisburg-Essen, Essen, Germany
| | - Albert Sickmann
- Leibniz-Institut für Analytische Wissenschaften - ISAS - e.V. Dortmund, Germany
| | - Angela Abicht
- Department of Neurology, Friedrich-Baur Institute, Munich, Germany
- MGZ - Medizinisch Genetisches Zentrum, Munich, Germany
| | - Florian Kraft
- Institute of Human Genetics und Genomic Medicine, RWTH-Aachen University, Aachen, Germany
| | - Tobias Ruck
- Department of Neurology, Medical Faculty, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Johann Böhm
- IGBMC (Institut de Génétique et de Biologie Moléculaire et Cellulaire), Inserm U1258, CNRS UMR7104, Université de Strasbourg, Illkirch, France
| | - Anne Schänzer
- Institute of Neuropathology, Justus Liebig University, Giessen, Germany
| | - Ulrike Schara-Schmidt
- Department of Pediatric Neurology, Centre for Neuromuscular Disorders, Centre for Translational Neuro- and Behavioral Sciences, University Duisburg-Essen, Essen, Germany
| | | | - Rita Horvath
- Department of Clinical Neurosciences, John Van Geest Centre for Brain Repair, School of Clinical Medicine, University of Cambridge, Cambridge, UK
| | - Andreas Roos
- Department of Pediatric Neurology, Centre for Neuromuscular Disorders, Centre for Translational Neuro- and Behavioral Sciences, University Duisburg-Essen, Essen, Germany
- Children's Hospital of Eastern Ontario Research Institute, Ottawa, ON, Canada
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3
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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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4
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Fay A, Garcia Y, Margeta M, Maharjan S, Jürgensen C, Briceño J, Garcia M, Yin S, Bassaganyas L, McMahon T, Hou YM, Fu YH, Ptáček LJ. A Mitochondrial tRNA Mutation Causes Axonal CMT in a Large Venezuelan Family. Ann Neurol 2020; 88:830-842. [PMID: 32715519 DOI: 10.1002/ana.25854] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Revised: 07/20/2020] [Accepted: 07/22/2020] [Indexed: 12/19/2022]
Abstract
OBJECTIVE The objective of this study was to identify the genetic cause for progressive peripheral nerve disease in a Venezuelan family. Despite the growing list of genes associated with Charcot-Marie-Tooth disease, many patients with axonal forms lack a genetic diagnosis. METHODS A pedigree was constructed, based on family clinical data. Next-generation sequencing of mitochondrial DNA (mtDNA) was performed for 6 affected family members. Muscle biopsies from 4 family members were used for analysis of muscle histology and ultrastructure, mtDNA sequencing, and RNA quantification. Ultrastructural studies were performed on sensory nerve biopsies from 2 affected family members. RESULTS Electrodiagnostic testing showed a motor and sensory axonal polyneuropathy. Pedigree analysis revealed inheritance only through the maternal line, consistent with mitochondrial transmission. Sequencing of mtDNA identified a mutation in the mitochondrial tRNAVal (mt-tRNAVal ) gene, m.1661A>G, present at nearly 100% heteroplasmy, which disrupts a Watson-Crick base pair in the T-stem-loop. Muscle biopsies showed chronic denervation/reinnervation changes, whereas biochemical analysis of electron transport chain (ETC) enzyme activities showed reduction in multiple ETC complexes. Northern blots from skeletal muscle total RNA showed severe reduction in abundance of mt-tRNAVal , and mildly increased mt-tRNAPhe , in subjects compared with unrelated age- and sex-matched controls. Nerve biopsies from 2 affected family members demonstrated ultrastructural mitochondrial abnormalities (hyperplasia, hypertrophy, and crystalline arrays) consistent with a mitochondrial neuropathy. CONCLUSION We identify a previously unreported cause of Charcot-Marie-Tooth (CMT) disease, a mutation in the mt-tRNAVal , in a Venezuelan family. This work expands the list of CMT-associated genes from protein-coding genes to a mitochondrial tRNA gene. ANN NEUROL 2020;88:830-842.
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Affiliation(s)
- Alexander Fay
- Department of Neurology, University of California, San Francisco, CA, USA
| | - Yngo Garcia
- Department of Biochemistry, Faculty of Medicine, University of The Andes, Mérida, Venezuela.,Unit of Surgery, Neurosurgery Service, Medical Surgery Clinical Institute, Mérida, Venezuela
| | - Marta Margeta
- Department of Pathology, University of California, San Francisco, CA, USA
| | - Sunita Maharjan
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA, USA
| | - Claudia Jürgensen
- Department of Biology, Faculty of Science, University of The Andes, Mérida, Venezuela
| | - Jose Briceño
- Physiotherapy and Rehabilitation Service, University Hospital of The Andes, Mérida, Venezuela
| | - Mariaelena Garcia
- Department of Biology, Faculty of Science, University of The Andes, Mérida, Venezuela
| | - Sitao Yin
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA, USA
| | - Laia Bassaganyas
- Department of Medical Genetics, University of Cambridge and Cardiovascular Research Institute, University of California, San Francisco, CA, USA
| | - Thomas McMahon
- Department of Neurology, University of California, San Francisco, CA, USA
| | - Ya-Ming Hou
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA, USA
| | - Ying-Hui Fu
- Department of Neurology, University of California, San Francisco, CA, USA
| | - Louis J Ptáček
- Department of Neurology, University of California, San Francisco, CA, USA
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5
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da Veiga MGA, Marecos C, Vieira JP, Conceição C. Leigh Syndrome with atypical cerebellum imaging features. eNeurologicalSci 2020; 18:100214. [PMID: 32123758 PMCID: PMC7037537 DOI: 10.1016/j.ensci.2019.100214] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2019] [Accepted: 11/18/2019] [Indexed: 12/01/2022] Open
Affiliation(s)
| | - Clara Marecos
- Department of Neuropediatrics, Hospital Dona Estefânia – Centro Hospitalar de Lisboa Central, 1169–045 Lisboa, Portugal
- Department of Pediatrics, Hospital Professor Doutor Fernando Fonseca, EPE, IC19, 2720–276 Amadora, Portugal
| | - José Pedro Vieira
- Department of Neuropediatrics, Hospital Dona Estefânia – Centro Hospitalar de Lisboa Central, 1169–045 Lisboa, Portugal
| | - Carla Conceição
- Department of Neuroradiology, Centro Hospitalar de Lisboa Central, 1150–199 Lisboa, Portugal
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6
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Li J, Suda K, Ueoka I, Tanaka R, Yoshida H, Okada Y, Okamoto Y, Hiramatsu Y, Takashima H, Yamaguchi M. Neuron-specific knockdown of Drosophila HADHB induces a shortened lifespan, deficient locomotive ability, abnormal motor neuron terminal morphology and learning disability. Exp Cell Res 2019; 379:150-158. [DOI: 10.1016/j.yexcr.2019.03.040] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Revised: 03/29/2019] [Accepted: 03/30/2019] [Indexed: 01/03/2023]
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7
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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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8
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Jang YH, Lim KI. Recent Advances in Mitochondria-Targeted Gene Delivery. Molecules 2018; 23:E2316. [PMID: 30208599 PMCID: PMC6225103 DOI: 10.3390/molecules23092316] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2018] [Revised: 09/06/2018] [Accepted: 09/08/2018] [Indexed: 11/16/2022] Open
Abstract
Mitochondria are the energy-producing organelles of cells. Mitochondrial dysfunctions link to various syndromes and diseases including myoclonic epilepsy and ragged-red fiber disease (MERRF), Leigh syndrome (LS), and Leber hereditary optic neuropathy (LHON). Primary mitochondrial diseases often result from mutations of mitochondrial genomes and nuclear genes that encode the mitochondrial components. However, complete intracellular correction of the mutated genetic parts relevant to mitochondrial structures and functions is technically challenging. Instead, there have been diverse attempts to provide corrected genetic materials with cells. In this review, we discuss recent novel physical, chemical and biological strategies, and methods to introduce genetic cargos into mitochondria of eukaryotic cells. Effective mitochondria-targeting gene delivery systems can reverse multiple mitochondrial disorders by enabling cells to produce functional mitochondrial components.
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Affiliation(s)
- Yoon-Ha Jang
- Department of Chemical and Biological Engineering, Sookmyung Women's University, Seoul 04310, Korea.
| | - Kwang-Il Lim
- Department of Chemical and Biological Engineering, Sookmyung Women's University, Seoul 04310, Korea.
- Institute of Advanced Materials and Systems, Sookmyung Women's University, Seoul 04310, Korea.
- Research Institute of ICT Convergence, Sookmyung Women's University, Seoul 04310, Korea.
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9
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Luigetti M, Primiano G, Cuccagna C, Bernardo D, Sauchelli D, Vollono C, Servidei S. Small fibre neuropathy in mitochondrial diseases explored with sudoscan. Clin Neurophysiol 2018; 129:1618-1623. [DOI: 10.1016/j.clinph.2018.04.755] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Revised: 03/30/2018] [Accepted: 04/29/2018] [Indexed: 01/16/2023]
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10
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Ciron J, Baron C, Boissonnot M, Neau JP, Magdelaine C, Vallat JM, Mathis S. Peripheral nervous system involvement in Leber's hereditary optic neuropathy. J Neurol Sci 2018; 388:94-96. [DOI: 10.1016/j.jns.2018.03.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Revised: 02/07/2018] [Accepted: 03/01/2018] [Indexed: 11/17/2022]
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11
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Dung VM, Suong DNA, Okamaoto Y, Hiramatsu Y, Thao DTP, Yoshida H, Takashima H, Yamaguchi M. Neuron-specific knockdown of Drosophila PDHB induces reduction of lifespan, deficient locomotive ability, abnormal morphology of motor neuron terminals and photoreceptor axon targeting. Exp Cell Res 2018; 366:92-102. [PMID: 29501567 DOI: 10.1016/j.yexcr.2018.02.035] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Revised: 02/24/2018] [Accepted: 02/27/2018] [Indexed: 02/03/2023]
Abstract
Pyruvate dehydrogenase complex deficiency (PDCD) is a common primary cause of defects in mitochondrial function and also can lead to peripheral neuropathy. Pyruvate dehydrogenase E1 component subunit beta (PDHB) is a subunit of pyruvate dehydrogenase E1, which is a well-known component of PDC. In Drosophila melanogaster, the CG11876 (dPDHB) gene is a homolog of human PDHB. In this study, we established a Drosophila model with neuron-specific knockdown of dPDHB to investigate its role in neuropathy pathogenesis. Knockdown of dPDHB in pan-neurons induced locomotor defects in both larval and adult stages, which were consistent with abnormal morphology of the motor neuron terminals at neuromuscular junctions and mitochondrial fragmentation in brains. Moreover, neuron-specific knockdown of dPDHB also shortened the lifespan of adult flies. In addition, flies with knockdown of dPDHB manifested a rough eye phenotype and aberrant photoreceptor axon targeting. These results with the Drosophila model suggest the involvement of PDHB in peripheral neuropathy.
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Affiliation(s)
- Vuu My Dung
- Department of Applied Biology, The Center for Advanced Insect Research, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan; Department of Molecular and Environmental Biotechnology, Faculty of Biology and Biotechnology, University of Science, Vietnam National University - Ho Chi Minh City, Ho Chi Minh City 700000, Vietnam
| | - Dang Ngoc Anh Suong
- Department of Applied Biology, The Center for Advanced Insect Research, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan
| | - Yuji Okamaoto
- Department of Neurology and Geriatrics, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Yu Hiramatsu
- Department of Neurology and Geriatrics, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Dang Thi Phuong Thao
- Department of Molecular and Environmental Biotechnology, Faculty of Biology and Biotechnology, University of Science, Vietnam National University - Ho Chi Minh City, Ho Chi Minh City 700000, Vietnam
| | - Hideki Yoshida
- Department of Applied Biology, The Center for Advanced Insect Research, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan
| | - Hiroshi Takashima
- Department of Neurology and Geriatrics, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Masamitsu Yamaguchi
- Department of Applied Biology, The Center for Advanced Insect Research, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan.
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12
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Other Inherited Neuropathies II. Neuromuscul Disord 2018. [DOI: 10.1007/978-981-10-5361-0_41] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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13
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Bovine and murine models highlight novel roles for SLC25A46 in mitochondrial dynamics and metabolism, with implications for human and animal health. PLoS Genet 2017; 13:e1006597. [PMID: 28376083 PMCID: PMC5380314 DOI: 10.1371/journal.pgen.1006597] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Accepted: 01/21/2017] [Indexed: 12/11/2022] Open
Abstract
Neuropathies are neurodegenerative diseases affecting humans and other mammals. Many genetic causes have been identified so far, including mutations of genes encoding proteins involved in mitochondrial dynamics. Recently, the “Turning calves syndrome”, a novel sensorimotor polyneuropathy was described in the French Rouge-des-Prés cattle breed. In the present study, we determined that this hereditary disease resulted from a single nucleotide substitution in SLC25A46, a gene encoding a protein of the mitochondrial carrier family. This mutation caused an apparent damaging amino-acid substitution. To better understand the function of this protein, we knocked out the Slc25a46 gene in a mouse model. This alteration affected not only the nervous system but also altered general metabolism, resulting in premature mortality. Based on optic microscopy examination, electron microscopy and on biochemical, metabolic and proteomic analyses, we showed that the Slc25a46 disruption caused a fusion/fission imbalance and an abnormal mitochondrial architecture that disturbed mitochondrial metabolism. These data extended the range of phenotypes associated with Slc25a46 dysfunction. Moreover, this Slc25a46 knock-out mouse model should be useful to further elucidate the role of SLC25A46 in mitochondrial dynamics. Mitochondria are essential organelles, the site of numerous biochemical reactions, with a critical role in delivering energy to cells, particularly in the nervous system. Consequently, disrupted mitochondrial function often results in neurodegenerative diseases, in humans and in other mammals. Herein, we determined that the “Turning calves syndrome”, a new hereditary sensorimotor polyneuropathy in the French Rouge-des-Prés cattle breed was due to a single substitution in SLC25A46, a gene encoding a protein of the mitochondrial carrier family. We created a mouse knock-out model and determined that disruption of this gene dramatically disturbed mitochondrial dynamics in various organs that resulted in altered metabolism and early death, indirectly confirming the gene identification in cattle. Moreover, our novel findings extended the range of phenotypes associated with polymorphisms of this gene and help to elucidate the role of SLC25A46 in mitochondrial function.
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14
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Yadak R, Sillevis Smitt P, van Gisbergen MW, van Til NP, de Coo IFM. Mitochondrial Neurogastrointestinal Encephalomyopathy Caused by Thymidine Phosphorylase Enzyme Deficiency: From Pathogenesis to Emerging Therapeutic Options. Front Cell Neurosci 2017; 11:31. [PMID: 28261062 PMCID: PMC5309216 DOI: 10.3389/fncel.2017.00031] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2016] [Accepted: 02/01/2017] [Indexed: 01/05/2023] Open
Abstract
Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is a progressive metabolic disorder caused by thymidine phosphorylase (TP) enzyme deficiency. The lack of TP results in systemic accumulation of deoxyribonucleosides thymidine (dThd) and deoxyuridine (dUrd). In these patients, clinical features include mental regression, ophthalmoplegia, and fatal gastrointestinal complications. The accumulation of nucleosides also causes imbalances in mitochondrial DNA (mtDNA) deoxyribonucleoside triphosphates (dNTPs), which may play a direct or indirect role in the mtDNA depletion/deletion abnormalities, although the exact underlying mechanism remains unknown. The available therapeutic approaches include dialysis and enzyme replacement therapy, both can only transiently reverse the biochemical imbalance. Allogeneic hematopoietic stem cell transplantation is shown to be able to restore normal enzyme activity and improve clinical manifestations in MNGIE patients. However, transplant related complications and disease progression result in a high mortality rate. New therapeutic approaches, such as adeno-associated viral vector and hematopoietic stem cell gene therapy have been tested in Tymp-/-Upp1-/- mice, a murine model for MNGIE. This review provides background information on disease manifestations of MNGIE with a focus on current management and treatment options. It also outlines the pre-clinical approaches toward future treatment of the disease.
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Affiliation(s)
- Rana Yadak
- Department of Neurology, Erasmus University Medical Center Rotterdam, Netherlands
| | - Peter Sillevis Smitt
- Department of Neurology, Erasmus University Medical Center Rotterdam, Netherlands
| | - Marike W van Gisbergen
- Department of Radiation Oncology (MaastRO-Lab), GROW - School for Oncology and Developmental Biology, Maastricht University Medical Centre Maastricht, Netherlands
| | - Niek P van Til
- Laboratory of Translational Immunology, University Medical Center Utrecht Utrecht, Netherlands
| | - Irenaeus F M de Coo
- Department of Neurology, Erasmus University Medical Center Rotterdam, Netherlands
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15
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Acute Ataxia in Children: A Review of the Differential Diagnosis and Evaluation in the Emergency Department. Pediatr Neurol 2016; 65:14-30. [PMID: 27789117 DOI: 10.1016/j.pediatrneurol.2016.08.025] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/31/2015] [Accepted: 08/26/2016] [Indexed: 11/21/2022]
Abstract
Acute ataxia in a pediatric patient poses a diagnostic dilemma for any physician. While the most common etiologies are benign, occasional individuals require urgent intervention. Children with stroke, toxic ingestion, infection, and neuro-inflammatory disorders frequently exhibit ataxia as an essential-if not the only-presenting feature. The available retrospective research utilize inconsistent definitions of acute ataxia, precluding the ability to pool data from these studies. No prospective data exist that report on patients presenting to the emergency department with ataxia. This review examines the reported causes of ataxia and attempts to group them into distinct categories: post-infectious and inflammatory central and peripheral phenomena, toxic ingestion, neurovascular, infectious and miscellaneous. From there, we synthesize the existing literature to understand which aspects of the history, physical exam, and ancillary testing might aid in narrowing the differential diagnosis. MRI is superior to CT in detecting inflammatory or vascular insults in the posterior fossa, though CT may be necessary in emergent situations. Lumbar puncture may be deferred until after admission in most instances, with suspicion for meningitis being the major exception. There is insufficient evidence to guide laboratory evaluation of serum, testing should be ordered based on clinical judgement-recommended studies include metabolic profiles and screening labs for metabolic disorders (lactate and ammonia). All patients should be reflexively screened for toxic ingestions.
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16
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Sonam K, Bindu PS, Srinivas Bharath MM, Govindaraj P, Gayathri N, Arvinda HR, Chiplunkar S, Nagappa M, Sinha S, Khan NA, Nunia V, Paramasivam A, Thangaraj K, Taly AB. Mitochondrial oxidative phosphorylation disorders in children: Phenotypic, genotypic and biochemical correlations in 85 patients from South India. Mitochondrion 2016; 32:42-49. [PMID: 27826120 DOI: 10.1016/j.mito.2016.11.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2016] [Revised: 10/12/2016] [Accepted: 11/03/2016] [Indexed: 12/13/2022]
Abstract
Mitochondrial oxidative phosphorylation (OXPHOS) disorders account for a variety of neuromuscular disorders in children. In this study mitochondrial respiratory chain enzymes were assayed in muscle tissue in a large cohort of children with varied neuromuscular presentations from June 2011 to December 2013. The biochemical enzyme deficiencies were correlated with the phenotypes, magnetic resonance imaging, histopathology and genetic findings to reach a final diagnosis. There were 85 children (mean age: 6.9±4.7years, M:F:2:1) with respiratory chain enzyme deficiency which included: isolated complex I (n=50, 60%), multiple complexes (n=24, 27%), complex IV (n=8, 9%) and complex III deficiencies (n=3, 4%). The most common neurological findings were ataxia (59%), hypotonia (59%) and involuntary movements (49%). A known mitochondrial syndrome was diagnosed in 27 (29%) and non-syndromic presentations in 57 (71%). Genetic analysis included complete sequencing of mitochondrial genome, SURF1, POLG1&2. It revealed variations in mitochondrial DNA (n=8), SURF1 (n=5), and POLG1 (n=3). This study, the first of its kind from India, highlights the wide range of clinical and imaging phenotypes and genetic heterogeneity in children with mitochondrial oxidative phosphorylation disorders.
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Affiliation(s)
- Kothari Sonam
- Department of Clinical Neurosciences, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, India; Neuromuscular Laboratory, Neurobiology Research Centre, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, India
| | - Parayil Sankaran Bindu
- Department of Neurology, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, India; Neuromuscular Laboratory, Neurobiology Research Centre, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, India.
| | - M M Srinivas Bharath
- Department of Neurochemistry, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, India
| | - Periyasamy Govindaraj
- Department of Neurology, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, India; Neuromuscular Laboratory, Neurobiology Research Centre, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, India
| | - Narayanappa Gayathri
- Department of Neuropathology, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, India; Neuromuscular Laboratory, Neurobiology Research Centre, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, India
| | - Hanumanthapura R Arvinda
- Department of Neuroimaging and Interventional Radiology, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, India
| | - Shwetha Chiplunkar
- Department of Clinical Neurosciences, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, India; Neuromuscular Laboratory, Neurobiology Research Centre, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, India
| | - Madhu Nagappa
- Department of Neurology, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, India; Neuromuscular Laboratory, Neurobiology Research Centre, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, India
| | - Sanjib Sinha
- Department of Neurology, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, India
| | | | - Vandana Nunia
- CSIR-Centre for Cellular and Molecular Biology, Hyderabad, India
| | | | | | - Arun B Taly
- Department of Neurology, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, India; Neuromuscular Laboratory, Neurobiology Research Centre, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, India
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17
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Neurophysiological profile of peripheral neuropathy associated with childhood mitochondrial disease. Mitochondrion 2016; 30:162-7. [PMID: 27475922 DOI: 10.1016/j.mito.2016.07.014] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Revised: 07/22/2016] [Accepted: 07/26/2016] [Indexed: 12/22/2022]
Abstract
INTRODUCTION Peripheral nerve involvement is common in mitochondrial disease but often unrecognised due to the prominent central nervous system features. Identification of the underlying neuropathy may assist syndrome classification, targeted genetic testing and rehabilitative interventions. METHODS Clinical data and the results of nerve conduction studies were obtained retrospectively from the records of four tertiary children's hospital metabolic disease, neuromuscular or neurophysiology services. Nerve conductions studies were also performed prospectively on children attending a tertiary metabolic disease service. Results were classified and analysed according to the underlying genetic cause. RESULTS Nerve conduction studies from 27 children with mitochondrial disease were included in the study (mitochondrial DNA (mtDNA) - 7, POLG - 7, SURF1 - 10, PDHc deficiency - 3). Four children with mtDNA mutations had a normal study while three had mild abnormalities in the form of an axonal sensorimotor neuropathy when not acutely unwell. One child with MELAS had a severe acute axonal motor neuropathy during an acute stroke-like episode that resolved over 12months. Five children with POLG mutations and disease onset beyond infancy had a sensory ataxic neuropathy with an onset in the second decade of life, while the two infants with POLG mutations had a demyelinating neuropathy. Seven of the 10 children with SURF1 mutations had a demyelinating neuropathy. All three children with PDHc deficiency had an axonal sensorimotor neuropathy. Unlike CMT, the neuropathy associated with mitochondrial disease was not length-dependent. CONCLUSIONS This is the largest study to date of peripheral neuropathy in genetically- classified childhood mitochondrial disease. Characterising the underlying neuropathy may assist with the diagnosis of the mitochondrial syndrome and should be an integral part of the assessment of children with suspected mitochondrial disease.
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18
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Peripheral neuropathy in genetically characterized patients with mitochondrial disorders: A study from south India. Mitochondrion 2016; 27:1-5. [DOI: 10.1016/j.mito.2015.12.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2015] [Revised: 12/24/2015] [Accepted: 12/29/2015] [Indexed: 11/23/2022]
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19
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Bennett B, Helbling D, Meng H, Jarzembowski J, Geurts AM, Friederich MW, Van Hove JLK, Lawlor MW, Dimmock DP. Potentially diagnostic electron paramagnetic resonance spectra elucidate the underlying mechanism of mitochondrial dysfunction in the deoxyguanosine kinase deficient rat model of a genetic mitochondrial DNA depletion syndrome. Free Radic Biol Med 2016; 92:141-151. [PMID: 26773591 PMCID: PMC5047058 DOI: 10.1016/j.freeradbiomed.2016.01.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Revised: 01/04/2016] [Accepted: 01/06/2016] [Indexed: 01/19/2023]
Abstract
A novel rat model for a well-characterized human mitochondrial disease, mitochondrial DNA depletion syndrome with associated deoxyguanosine kinase (DGUOK) deficiency, is described. The rat model recapitulates the pathologic and biochemical signatures of the human disease. The application of electron paramagnetic (spin) resonance (EPR) spectroscopy to the identification and characterization of respiratory chain abnormalities in the mitochondria from freshly frozen tissue of the mitochondrial disease model rat is introduced. EPR is shown to be a sensitive technique for detecting mitochondrial functional abnormalities in situ and, here, is particularly useful in characterizing the redox state changes and oxidative stress that can result from depressed expression and/or diminished specific activity of the distinct respiratory chain complexes. As EPR requires no sample preparation or non-physiological reagents, it provides information on the status of the mitochondrion as it was in the functioning state. On its own, this information is of use in identifying respiratory chain dysfunction; in conjunction with other techniques, the information from EPR shows how the respiratory chain is affected at the molecular level by the dysfunction. It is proposed that EPR has a role in mechanistic pathophysiological studies of mitochondrial disease and could be used to study the impact of new treatment modalities or as an additional diagnostic tool.
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Affiliation(s)
- Brian Bennett
- National Biomedical EPR Center, Department of Biophysics, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA.
| | - Daniel Helbling
- Human Molecular Genetics Center and Division of Genetics, Department of Pediatrics, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA.
| | - Hui Meng
- Division of Pediatric Pathology, Department of Pathology and Laboratory Medicine, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA.
| | - Jason Jarzembowski
- Division of Pediatric Pathology, Department of Pathology and Laboratory Medicine, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA.
| | - Aron M Geurts
- Department of Physiology, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA.
| | - Marisa W Friederich
- Clinical Genetics and Metabolism, Department of Pediatrics, University of Colorado, Mailstop 8400, 13121 East 17th Avenue, Aurora, CO 80045, USA.
| | - Johan L K Van Hove
- Clinical Genetics and Metabolism, Department of Pediatrics, University of Colorado, Mailstop 8400, 13121 East 17th Avenue, Aurora, CO 80045, USA.
| | - Michael W Lawlor
- Division of Pediatric Pathology, Department of Pathology and Laboratory Medicine, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA.
| | - David P Dimmock
- Human Molecular Genetics Center and Division of Genetics, Department of Pediatrics, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA.
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20
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Luigetti M, Sauchelli D, Primiano G, Cuccagna C, Bernardo D, Lo Monaco M, Servidei S. Peripheral neuropathy is a common manifestation of mitochondrial diseases: a single-centre experience. Eur J Neurol 2016; 23:1020-7. [DOI: 10.1111/ene.12954] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Accepted: 11/26/2015] [Indexed: 12/16/2022]
Affiliation(s)
- M. Luigetti
- Department of Geriatrics; Neurosciences and Orthopedics; Institute of Neurology; Catholic University of the Sacred Heart; Rome Italy
| | - D. Sauchelli
- Department of Geriatrics; Neurosciences and Orthopedics; Institute of Neurology; Catholic University of the Sacred Heart; Rome Italy
| | - G. Primiano
- Department of Geriatrics; Neurosciences and Orthopedics; Institute of Neurology; Catholic University of the Sacred Heart; Rome Italy
| | - C. Cuccagna
- Department of Geriatrics; Neurosciences and Orthopedics; Institute of Neurology; Catholic University of the Sacred Heart; Rome Italy
| | - D. Bernardo
- Department of Geriatrics; Neurosciences and Orthopedics; Institute of Neurology; Catholic University of the Sacred Heart; Rome Italy
| | - M. Lo Monaco
- Department of Geriatrics; Neurosciences and Orthopedics; Institute of Neurology; Catholic University of the Sacred Heart; Rome Italy
| | - S. Servidei
- Department of Geriatrics; Neurosciences and Orthopedics; Institute of Neurology; Catholic University of the Sacred Heart; Rome Italy
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21
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Renault F, Flores-Guevara R, Baudon JJ, Vazquez MP. Congenital multiple cranial neuropathies: Relevance of orofacial electromyography in infants. Muscle Nerve 2015; 52:754-8. [DOI: 10.1002/mus.24636] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Revised: 02/07/2015] [Accepted: 02/27/2015] [Indexed: 11/10/2022]
Affiliation(s)
- Francis Renault
- Clinical Neurophysiology Unit, Hôpital Armand-Trousseau, Assistance Publique-Hôpitaux de Paris; 28 avenue Arnold-Netter, 75571 Paris 12 France
| | - Roberto Flores-Guevara
- Clinical Neurophysiology Unit, Hôpital Armand-Trousseau, Assistance Publique-Hôpitaux de Paris; 28 avenue Arnold-Netter, 75571 Paris 12 France
- Facultad de Medicina, Universidad Nacional Mayor de San Marcos; Lima Peru
| | | | - Marie-Paule Vazquez
- Faculté de Médecine René-Descartes, Université Paris 5; Paris France
- Department of Maxillofacial Surgery; Hôpital Necker-Enfants Malades, Assistance Publique-Hôpitaux de Paris; Paris France
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22
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The cellular and molecular progression of mitochondrial dysfunction induced by 2,4-dinitrophenol in developing zebrafish embryos. Differentiation 2015; 89:51-69. [PMID: 25771346 DOI: 10.1016/j.diff.2015.01.001] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2014] [Revised: 01/22/2015] [Accepted: 01/27/2015] [Indexed: 12/18/2022]
Abstract
The etiology of mitochondrial disease is poorly understood. Furthermore, treatment options are limited, and diagnostic methods often lack the sensitivity to detect disease in its early stages. Disrupted oxidative phosphorylation (OXPHOS) that inhibits ATP production is a common phenotype of mitochondrial disorders that can be induced in zebrafish by exposure to 2,4-dinitrophenol (DNP), a FDA-banned weight-loss agent and EPA-regulated environmental toxicant, traditionally used in research labs as an uncoupler of OXPHOS. Despite the DNP-induced OXPHOS inhibition we observed using in vivo respirometry, the development of the DNP-treated and control zebrafish were largely similar during the first half of embryogenesis. During this period, DNP-treated embryos induced gene expression of mitochondrial and nuclear genes that stimulated the production of new mitochondria and increased glycolysis to yield normal levels of ATP. DNP-treated embryos were incapable of sustaining this mitochondrial biogenic response past mid-embryogenesis, as shown by significantly lowered ATP production and ATP levels, decreased gene expression, and the onset of developmental defects. Examining neural tissues commonly affected by mitochondrial disease, we found that DNP exposure also inhibited motor neuron axon arbor outgrowth and the proper formation of the retina. We observed and quantified the molecular and physiological progression of mitochondrial dysfunction during development with this new model of OXPHOS dysfunction, which has great potential for use in diagnostics and therapies for mitochondrial disease.
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23
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Pareyson D, Piscosquito G, Moroni I, Salsano E, Zeviani M. Peripheral neuropathy in mitochondrial disorders. Lancet Neurol 2013; 12:1011-24. [PMID: 24050734 DOI: 10.1016/s1474-4422(13)70158-3] [Citation(s) in RCA: 81] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Why is peripheral neuropathy common but mild in many mitochondrial disorders, and why is it, in some cases, the predominant or only manifestation? Although this question remains largely unanswered, recent advances in cellular and molecular biology have begun to clarify the importance of mitochondrial functioning and distribution in the peripheral nerve. Mutations in proteins involved in mitochondrial dynamics (ie, fusion and fission) frequently result in a Charcot-Marie-Tooth phenotype. Peripheral neuropathies with different phenotypic presentations occur in mitochondrial diseases associated with abnormalities in mitochondrial DNA replication and maintenance, or associated with defects in mitochondrial respiratory chain complex V. Our knowledge of mitochondrial disorders is rapidly growing as new nuclear genes are identified and new phenotypes described. Early diagnosis of mitochondrial disorders, essential to provide appropriate genetic counselling, has become crucial in a few treatable conditions. Recognising and diagnosing an underlying mitochondrial defect in patients presenting with peripheral neuropathy is therefore of paramount importance.
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Affiliation(s)
- Davide Pareyson
- Clinic of Central and Peripheral Degenerative Neuropathies Unit, Department of Clinical Neurosciences, Milan, Italy.
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24
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Lu J, Huang Y. Childhood mitochondrial encephalomyopathies: clinical course, diagnosis, neuroimaging findings, mtDNA mutations and outcome in six children. Ital J Pediatr 2013; 39:60. [PMID: 24069936 PMCID: PMC3849968 DOI: 10.1186/1824-7288-39-60] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/15/2013] [Accepted: 09/21/2013] [Indexed: 11/29/2022] Open
Abstract
Mitochondrial dysfunction manifests in many forms during childhood. There is no effective therapy for the condition; hence symptomatic therapy is the only option. The effect of symptomatic therapy are not well known. We present clinical course, diagnosis and effect of current treatments for six children suffering from mitochondrial encephalomyopathy identified by clinical demonstrations, brain MRI findings and DNA mutations. Two were male and four were female. Their age ranged between 2 and 17 years. Skeletal muscle biopsies were obtained in three and one showed misshaped and enlarged mitochondria under electron microscope. mtDNA mutation frequency was >30%. Five children were diagnosed with MELAS (mitochondrial encephalopathy, lactic acidosis, and strokelike episodes) and one with Leigh’s syndrome (LS). All were given cocktail and symptomatic treatments. One of the five MELAS children died from severe complications. The other four MELAS children remain alive; four showed improvement, and one remained unresponsive. Of the four who showed improvement, two do not have any abnormal signs and the other two have some degree of motor developmental delay and myotrophy. The LS child is doing well except for ataxia. Until better therapy such as mitochondrial gene therapy is available, cocktail and symptomatic treatments could at least stabilize these children.
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Affiliation(s)
- Jun Lu
- Department of Pediatrics Haikou Municipal People's Hospital, 43 Renmin Road, Haikou, Hainan Province 570208, P,R, China.
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25
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Kennerson ML, Yiu EM, Chuang DT, Kidambi A, Tso SC, Ly C, Chaudhry R, Drew AP, Rance G, Delatycki MB, Züchner S, Ryan MM, Nicholson GA. A new locus for X-linked dominant Charcot-Marie-Tooth disease (CMTX6) is caused by mutations in the pyruvate dehydrogenase kinase isoenzyme 3 (PDK3) gene. Hum Mol Genet 2013; 22:1404-16. [PMID: 23297365 PMCID: PMC3596851 DOI: 10.1093/hmg/dds557] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2012] [Revised: 12/16/2012] [Accepted: 12/27/2012] [Indexed: 01/30/2023] Open
Abstract
Hereditary motor and sensory disorders of the peripheral nerve form one of the most common groups of human genetic diseases collectively called Charcot-Marie-Tooth (CMT) neuropathy. Using linkage analysis in a three generation kindred, we have mapped a new locus for X-linked dominant CMT to chromosome Xp22.11. A microsatellite scan of the X chromosome established significant linkage to several markers including DXS993 (Zmax = 3.16; θ = 0.05). Extended haplotype analysis refined the linkage region to a 1.43-Mb interval flanked by markers DXS7110 and DXS8027. Whole exome sequencing identified a missense mutation c.G473A (p.R158H) in the pyruvate dehydrogenase kinase isoenzyme 3 (PDK3) gene. The change localized within the 1.43-Mb linkage interval, segregated with the affected phenotype and was excluded in ethnically matched control chromosomes. PDK3 is one of the four isoenzymes regulating the pyruvate dehydrogenase complex (PDC), by reversible phosphorylation, and is a nuclear-coded protein located in the mitochondrial matrix. PDC catalyzes the oxidative decarboxylation of pyruvate to acetyl CoA and is a key enzyme linking glycolysis to the energy-producing Krebs cycle and lipogenic pathways. We found that the R158H mutation confers enzyme hyperactivity and binds with stronger affinity than the wild-type to the inner-lipoyl (L2) domain of the E2p chain of PDC. Our findings suggest a reduced pyruvate flux due to R158H mutant PDK3-mediated hyper-phosphorylation of the PDC as the underlying pathogenic cause of peripheral neuropathy. The results highlight an important causative link between peripheral nerve degeneration and an essential bioenergetic or biosynthetic pathway required for the maintenance of peripheral nerves.
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Affiliation(s)
- Marina L Kennerson
- Northcott Neuroscience Laboratory, ANZAC Research Institute, Concord, NSW, Australia.
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