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Rajan-Babu IS, Dolzhenko E, Eberle MA, Friedman JM. Sequence composition changes in short tandem repeats: heterogeneity, detection, mechanisms and clinical implications. Nat Rev Genet 2024:10.1038/s41576-024-00696-z. [PMID: 38467784 DOI: 10.1038/s41576-024-00696-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/19/2024] [Indexed: 03/13/2024]
Abstract
Short tandem repeats (STRs) are a class of repetitive elements, composed of tandem arrays of 1-6 base pair sequence motifs, that comprise a substantial fraction of the human genome. STR expansions can cause a wide range of neurological and neuromuscular conditions, known as repeat expansion disorders, whose age of onset, severity, penetrance and/or clinical phenotype are influenced by the length of the repeats and their sequence composition. The presence of non-canonical motifs, depending on the type, frequency and position within the repeat tract, can alter clinical outcomes by modifying somatic and intergenerational repeat stability, gene expression and mutant transcript-mediated and/or protein-mediated toxicities. Here, we review the diverse structural conformations of repeat expansions, technological advances for the characterization of changes in sequence composition, their clinical correlations and the impact on disease mechanisms.
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Affiliation(s)
- Indhu-Shree Rajan-Babu
- Department of Medical Genetics, The University of British Columbia, and Children's & Women's Hospital, Vancouver, British Columbia, Canada.
| | | | | | - Jan M Friedman
- Department of Medical Genetics, The University of British Columbia, and Children's & Women's Hospital, Vancouver, British Columbia, Canada
- BC Children's Hospital Research Institute, Vancouver, British Columbia, Canada
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2
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Méreaux JL, Davoine CS, Pellerin D, Coarelli G, Coutelier M, Ewenczyk C, Monin ML, Anheim M, Le Ber I, Thobois S, Gobert F, Guillot-Noël L, Forlani S, Jornea L, Heinzmann A, Sangare A, Gaymard B, Guyant-Maréchal L, Charles P, Marelli C, Honnorat J, Degos B, Tison F, Sangla S, Simonetta-Moreau M, Salachas F, Tchikviladzé M, Castelnovo G, Mochel F, Klebe S, Castrioto A, Fenu S, Méneret A, Bourdain F, Wandzel M, Roth V, Bonnet C, Riant F, Stevanin G, Noël S, Fauret-Amsellem AL, Bahlo M, Lockhart PJ, Brais B, Renaud M, Brice A, Durr A. Clinical and genetic keys to cerebellar ataxia due to FGF14 GAA expansions. EBioMedicine 2024; 99:104931. [PMID: 38150853 PMCID: PMC10784672 DOI: 10.1016/j.ebiom.2023.104931] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2023] [Revised: 11/26/2023] [Accepted: 12/06/2023] [Indexed: 12/29/2023] Open
Abstract
BACKGROUND SCA27B caused by FGF14 intronic heterozygous GAA expansions with at least 250 repeats accounts for 10-60% of cases with unresolved cerebellar ataxia. We aimed to assess the size and frequency of FGF14 expanded alleles in individuals with cerebellar ataxia as compared with controls and to characterize genetic and clinical variability. METHODS We sized this repeat in 1876 individuals from France sampled for research purposes in this cross-sectional study: 845 index cases with cerebellar ataxia and 324 affected relatives, 475 controls, as well as 119 cases with spastic paraplegia, and 113 with familial essential tremor. FINDINGS A higher frequency of expanded allele carriers in index cases with ataxia was significant only above 300 GAA repeats (10.1%, n = 85) compared with controls (1.1%, n = 5) (p < 0.0001) whereas GAA250-299 alleles were detected in 1.7% of both groups. Eight of 14 index cases with GAA250-299 repeats had other causal pathogenic variants (4/14) and/or discordance of co-segregation (5/14), arguing against GAA causality. We compared the clinical signs in 127 GAA≥300 carriers to cases with non-expanded GAA ataxia resulting in defining a key phenotype triad: onset after 45 years, downbeat nystagmus, episodic ataxic features including diplopia; and a frequent absence of dysarthria. All maternally transmitted alleles above 100 GAA were unstable with a median expansion of +18 repeats per generation (r2 = 0.44; p < 0.0001). In comparison, paternally transmitted alleles above 100 GAA mostly decreased in size (-15 GAA (r2 = 0.63; p < 0.0001)), resulting in the transmission bias observed in SCA27B pedigrees. INTERPRETATION SCA27B diagnosis must consider both the phenotype and GAA expansion size. In carriers of GAA250-299 repeats, the absence of documented familial transmission and a presentation deviating from the key SCA27B phenotype, should prompt the search for an alternative cause. Affected fathers have a reduced risk of having affected children, which has potential implications for genetic counseling. FUNDING This work was supported by the Fondation pour la Recherche Médicale, grant number 13338 to JLM, the Association Connaître les Syndrome Cérébelleux - France (to GS) and by the European Union's Horizon 2020 research and innovation program under grant agreement No 779257 ("SOLVE-RD" to GS). DP holds a Fellowship award from the Canadian Institutes of Health Research (CIHR). SK received a grant (01GM1905C) from the Federal Ministry of Education and Research, Germany, through the TreatHSP network. This work was supported by the Australian Government National Health and Medical Research Council grants (GNT2001513 and MRFF2007677) to MB and PJL.
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Affiliation(s)
- Jean-Loup Méreaux
- Sorbonne Université, Paris Brain Institute - ICM, Inserm, CNRS, AP-HP, Paris, France
| | - Claire-Sophie Davoine
- Sorbonne Université, Paris Brain Institute - ICM, Inserm, CNRS, AP-HP, Paris, France
| | - David Pellerin
- Department of Neurology and Neurosurgery, Montreal Neurological Hospital and Institute, McGill University, Montreal, QC, Canada; Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology and the National Hospital for Neurology and Neurosurgery, University College London, London, United Kingdom
| | - Giulia Coarelli
- Sorbonne Université, Paris Brain Institute - ICM, Inserm, CNRS, AP-HP, Paris, France; Unité de Génétique Clinique, AP-HP, Hôpital Pitié-Salpêtrière, Paris, France
| | - Marie Coutelier
- Sorbonne Université, Paris Brain Institute - ICM, Inserm, CNRS, AP-HP, Paris, France
| | - Claire Ewenczyk
- Sorbonne Université, Paris Brain Institute - ICM, Inserm, CNRS, AP-HP, Paris, France; Unité de Génétique Clinique, AP-HP, Hôpital Pitié-Salpêtrière, Paris, France
| | - Marie-Lorraine Monin
- Centre de Reference Maladies Rares « Neurogénétique », Service de Génétique Médicale, Bordeaux University Hospital (CHU Bordeaux), 33000, Bordeaux, France
| | - Mathieu Anheim
- Department of Neurology, Strasbourg University Hospital, 67098, Strasbourg, France; Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), INSERM-U964, CNRS-UMR7104, University of Strasbourg, 67400, Illkirch-Graffenstaden, France
| | - Isabelle Le Ber
- Sorbonne Université, Paris Brain Institute - ICM, Inserm, CNRS, AP-HP, Paris, France
| | - Stéphane Thobois
- Department of Neurology C, Expert Parkinson Centre NS-Park/F-CRIN, Hospices Civils de Lyon, Pierre Wertheimer Neurological Hospital, 69677, Bron, France; Marc Jeannerod Cognitive Neuroscience Institute, CNRS, UMR 5229, Bron, France; Faculté de Médecine Et de Maïeutique Lyon Sud Charles Mérieux, Université Claude Bernard Lyon 1, Université de Lyon, Lyon, France
| | - Florent Gobert
- Neuro-Intensive Care Unit, Hospices Civils de Lyon, Neurological Hospital Pierre-Wertheimer, Lyon, France; University Lyon I, Villeurbanne, France
| | - Léna Guillot-Noël
- Sorbonne Université, Paris Brain Institute - ICM, Inserm, CNRS, AP-HP, Paris, France
| | - Sylvie Forlani
- Sorbonne Université, Paris Brain Institute - ICM, Inserm, CNRS, AP-HP, Paris, France
| | - Ludmila Jornea
- Sorbonne Université, Paris Brain Institute - ICM, Inserm, CNRS, AP-HP, Paris, France
| | - Anna Heinzmann
- Sorbonne Université, Paris Brain Institute - ICM, Inserm, CNRS, AP-HP, Paris, France
| | - Aude Sangare
- Sorbonne Université, Paris Brain Institute - ICM, Inserm, CNRS, AP-HP, Paris, France; Department of Neurophysiology, University Hospital Group APHP-Sorbonne University, Pitié-Salpêtrière Site, Paris, France
| | - Bertrand Gaymard
- Department of Neurophysiology, University Hospital Group APHP-Sorbonne University, Pitié-Salpêtrière Site, Paris, France
| | - Lucie Guyant-Maréchal
- Neurophysiology Department, Rouen University Hospital, Rouen, France; Medical Genetics Department, Rouen University Hospital, Rouen, France
| | - Perrine Charles
- Sorbonne Université, Paris Brain Institute - ICM, Inserm, CNRS, AP-HP, Paris, France; Unité de Génétique Clinique, AP-HP, Hôpital Pitié-Salpêtrière, Paris, France
| | - Cecilia Marelli
- MMDN, University Montpellier, EPHE, INSERM and Expert Center for Neurogenetic Diseases, CHU, 34095, Montpellier, France
| | - Jérôme Honnorat
- Reference Center for Paraneoplastic Neurological Syndromes and Autoimmune Encephalitis, Hospices Civils de Lyon, MeLiS Institute UMR CNRS 5284 - INSERM U1314, Université Claude Bernard Lyon 1, Lyon, France
| | - Bertrand Degos
- Neurology Department, Avicenne Hospital, APHP, Hôpitaux Universitaires de Paris-Seine Saint Denis (HUPSSD), Sorbonne Paris Nord, Réseau NS-PARK/FCRIN, Bobigny, France
| | - François Tison
- Institut des Maladies Neurodégénératives-Clinique (IMNc), University Hospital Bordeaux, Bordeaux, France; Institut des Maladies Neurodégénératives, CNRS, UMR 5293, Bordeaux University, Bordeaux, France
| | - Sophie Sangla
- Neurology Department, Hôpital Fondation Adolphe de Rothschild, Paris, France
| | - Marion Simonetta-Moreau
- Department of Neurology, University Hospital of Toulouse, 31300, Toulouse, France; Toulouse NeuroImaging Center (ToNIC), Inserm, UPS, Université de Toulouse, 31024, Toulouse, France; Clinical Investigation Center (CIC 1436), Toulouse University Hospital, INSERM, 31059, Toulouse, France
| | - François Salachas
- Sorbonne Université, Paris Brain Institute - ICM, Inserm, CNRS, AP-HP, Paris, France; Département de Neurologie, Assistance Publique Hôpitaux de Paris (APHP), Centre de Référence SLA Ile de France, Hôpital de la Pitié-Salpêtrière, Paris, France
| | - Maya Tchikviladzé
- Sorbonne Université, Paris Brain Institute - ICM, Inserm, CNRS, AP-HP, Paris, France
| | - Giovanni Castelnovo
- Department of Neurology, Nîmes University Hospital, Hopital Caremeau, Nîmes, France
| | - Fanny Mochel
- Sorbonne Université, Paris Brain Institute - ICM, Inserm, CNRS, AP-HP, Paris, France
| | - Stephan Klebe
- Department of Neurology, University Hospital Essen, Essen, Germany
| | - Anna Castrioto
- Univ. Grenoble Alpes, Inserm, U1216, CHU Grenoble Alpes, Grenoble Institut Neurosciences, Neurology Department, 38000, Grenoble, France
| | - Silvia Fenu
- Unit of Rare Neurological Diseases, Department of Clinical Neurosciences, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Aurélie Méneret
- Sorbonne Université, Paris Brain Institute - ICM, Inserm, CNRS, AP-HP, Paris, France; Département de Neurologie, Hôpital de la Pitié-Salpêtrière, Assistance Publique Hôpitaux de Paris (APHP), Paris, France
| | - Frédéric Bourdain
- Service de Neurologie, Centre Hospitalier de la Côte Basque, Bayonne, France
| | - Marion Wandzel
- Laboratoire de Génétique Médicale, CHRU Nancy, Université de Lorraine, INSERM UMR_S1256, NGERE, Nancy, France
| | - Virginie Roth
- Laboratoire de Génétique Médicale, CHRU Nancy, Université de Lorraine, INSERM UMR_S1256, NGERE, Nancy, France
| | - Céline Bonnet
- Laboratoire de Génétique Médicale, CHRU Nancy, Université de Lorraine, INSERM UMR_S1256, NGERE, Nancy, France
| | - Florence Riant
- Service de Génétique Moléculaire Neurovasculaire, AP-HP, Saint Louis Hospital, Paris, France
| | - Giovanni Stevanin
- Sorbonne Université, Paris Brain Institute - ICM, Inserm, CNRS, AP-HP, Paris, France; Bordeaux University (Université de Bordeaux), Equipe « Neurogénétique Translationnelle - NRGEN », INCIA CNRS UMR5287, EPHE, 33000, Bordeaux, France
| | - Sandrine Noël
- Unité de Neurogénétique Moléculaire et Cellulaire, AP-HP, Hôpital Pitié-Salpêtrière, Paris, France
| | | | - Melanie Bahlo
- Population Health and Immunity Division, Walter and Eliza Hall Institute of Medical Research, Department of Medical Biology, University of Melbourne, Parkville, VIC, 3052, Australia
| | - Paul J Lockhart
- Bruce Lefroy Centre, Murdoch Children's Research Institute and Department of Paediatrics, University of Melbourne, Parkville, VIC, 3052, Australia
| | - Bernard Brais
- Department of Neurology and Neurosurgery, Montreal Neurological Hospital and Institute, McGill University, Montreal, QC, Canada
| | - Mathilde Renaud
- Service de Génétique Clinique et de Neurologie, Hôpital Brabois, Nancy, France; INSERM Unité 1256 N-GERE (Nutrition-Genetics and Environmental Risk Exposure), Université de Lorraine, Nancy, France
| | - Alexis Brice
- Sorbonne Université, Paris Brain Institute - ICM, Inserm, CNRS, AP-HP, Paris, France
| | - Alexandra Durr
- Sorbonne Université, Paris Brain Institute - ICM, Inserm, CNRS, AP-HP, Paris, France; Unité de Génétique Clinique, AP-HP, Hôpital Pitié-Salpêtrière, Paris, France.
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Krasilnikova MM, Humphries CL, Shinsky EM. Friedreich's ataxia: new insights. Emerg Top Life Sci 2023; 7:313-323. [PMID: 37698160 DOI: 10.1042/etls20230017] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Revised: 08/09/2023] [Accepted: 08/29/2023] [Indexed: 09/13/2023]
Abstract
Friedreich ataxia (FRDA) is an inherited disease that is typically caused by GAA repeat expansion within the first intron of the FXN gene coding for frataxin. This results in the frataxin deficiency that affects mostly muscle, nervous, and cardiovascular systems with progressive worsening of the symptoms over the years. This review summarizes recent progress that was achieved in understanding of molecular mechanism of the disease over the last few years and latest treatment strategies focused on overcoming the frataxin deficiency.
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Affiliation(s)
- Maria M Krasilnikova
- Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania, U.S.A
| | - Casey L Humphries
- Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania, U.S.A
| | - Emily M Shinsky
- Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania, U.S.A
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4
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Maheshwari S, Vilema-Enríquez G, Wade-Martins R. Patient-derived iPSC models of Friedreich ataxia: a new frontier for understanding disease mechanisms and therapeutic application. Transl Neurodegener 2023; 12:45. [PMID: 37726850 PMCID: PMC10510273 DOI: 10.1186/s40035-023-00376-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2023] [Accepted: 08/28/2023] [Indexed: 09/21/2023] Open
Abstract
Friedreich ataxia (FRDA) is a rare genetic multisystem disorder caused by a pathological GAA trinucleotide repeat expansion in the FXN gene. The numerous drawbacks of historical cellular and rodent models of FRDA have caused difficulty in performing effective mechanistic and translational studies to investigate the disease. The recent discovery and subsequent development of induced pluripotent stem cell (iPSC) technology provides an exciting platform to enable enhanced disease modelling for studies of rare genetic diseases. Utilising iPSCs, researchers have created phenotypically relevant and previously inaccessible cellular models of FRDA. These models enable studies of the molecular mechanisms underlying GAA-induced pathology, as well as providing an exciting tool for the screening and testing of novel disease-modifying therapies. This review explores how the use of iPSCs to study FRDA has developed over the past decade, as well as discussing the enormous therapeutic potentials of iPSC-derived models, their current limitations and their future direction within the field of FRDA research.
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Affiliation(s)
- Saumya Maheshwari
- Department of Physiology, Anatomy and Genetics, Kavli Institute for Nanoscience Discovery, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK
| | - Gabriela Vilema-Enríquez
- Department of Physiology, Anatomy and Genetics, Kavli Institute for Nanoscience Discovery, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK
| | - Richard Wade-Martins
- Department of Physiology, Anatomy and Genetics, Kavli Institute for Nanoscience Discovery, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK.
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5
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Rastokina A, Cebrián J, Mozafari N, Mandel NH, Smith CI, Lopes M, Zain R, Mirkin S. Large-scale expansions of Friedreich's ataxia GAA•TTC repeats in an experimental human system: role of DNA replication and prevention by LNA-DNA oligonucleotides and PNA oligomers. Nucleic Acids Res 2023; 51:8532-8549. [PMID: 37216608 PMCID: PMC10484681 DOI: 10.1093/nar/gkad441] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Revised: 05/02/2023] [Accepted: 05/20/2023] [Indexed: 05/24/2023] Open
Abstract
Friedreich's ataxia (FRDA) is caused by expansions of GAA•TTC repeats in the first intron of the human FXN gene that occur during both intergenerational transmissions and in somatic cells. Here we describe an experimental system to analyze large-scale repeat expansions in cultured human cells. It employs a shuttle plasmid that can replicate from the SV40 origin in human cells or be stably maintained in S. cerevisiae utilizing ARS4-CEN6. It also contains a selectable cassette allowing us to detect repeat expansions that accumulated in human cells upon plasmid transformation into yeast. We indeed observed massive expansions of GAA•TTC repeats, making it the first genetically tractable experimental system to study large-scale repeat expansions in human cells. Further, GAA•TTC repeats stall replication fork progression, while the frequency of repeat expansions appears to depend on proteins implicated in replication fork stalling, reversal, and restart. Locked nucleic acid (LNA)-DNA mixmer oligonucleotides and peptide nucleic acid (PNA) oligomers, which interfere with triplex formation at GAA•TTC repeats in vitro, prevented the expansion of these repeats in human cells. We hypothesize, therefore, that triplex formation by GAA•TTC repeats stall replication fork progression, ultimately leading to repeat expansions during replication fork restart.
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Affiliation(s)
| | - Jorge Cebrián
- Department of Biology, Tufts University, Medford, MA 02155, USA
| | - Negin Mozafari
- Department of Laboratory Medicine, Translational Research Center Karolinska (TRACK), Karolinska Institutet, Karolinska University Hospital, SE-171 77 Stockholm, Sweden
| | | | - C I Edvard Smith
- Department of Laboratory Medicine, Translational Research Center Karolinska (TRACK), Karolinska Institutet, Karolinska University Hospital, SE-171 77 Stockholm, Sweden
| | - Massimo Lopes
- Institute of Molecular Cancer Research, University of Zurich, Zurich 8057, Switzerland
| | - Rula Zain
- Department of Laboratory Medicine, Translational Research Center Karolinska (TRACK), Karolinska Institutet, Karolinska University Hospital, SE-171 77 Stockholm, Sweden
- Center for Rare Diseases, Karolinska University Hospital, SE-17176 Stockholm, Sweden
| | - Sergei M Mirkin
- Department of Biology, Tufts University, Medford, MA 02155, USA
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Munoz-Zuluaga C, Gertz M, Yost-Bido M, Greco A, Gorman N, Chen A, Kooner V, Rosenberg JB, De BP, Kaminsky SM, Borczuk A, Ricart Arbona RJ, Martin HR, Monette S, Khanna R, Barth JA, Crystal RG, Sondhi D. Identification of Safe and Effective Intravenous Dose of AAVrh.10hFXN to Treat the Cardiac Manifestations of Friedreich's Ataxia. Hum Gene Ther 2023; 34:605-615. [PMID: 37166361 PMCID: PMC10354731 DOI: 10.1089/hum.2023.020] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Accepted: 04/16/2023] [Indexed: 05/12/2023] Open
Abstract
Friedreich's ataxia (FA) is a life-threatening autosomal recessive disorder characterized by neurological and cardiac dysfunction. Arrhythmias and heart failure are the main cause of premature death. From prior studies in murine models of FA, adeno-associated virus encoding the normal human frataxin gene (AAVrh.10hFXN) effectively treated the cardiac manifestations of the disease. However, the therapeutic dose window is limited by high level of human frataxin (hFXN) gene expression associated with toxicity. As a therapeutic goal, since FA heterozygotes have no clinical manifestations of FA, we estimated the level of frataxin (FXN) necessary to convert the heart of a homozygote to that of a heterozygote. In noncardiac cells, FA heterozygotes have 30-80% of normal FXN levels (17.7-47.2 ng/mg, average 32.5 ng/mg) and FA homozygotes 2-30% normal levels (1.2-17.7 ng/mg, average 9.4 ng/mg). Therefore, an AAV vector would need to augment endogenous in an FA homozygote by >8.3 ng/mg. To determine the required dose of AAVrh.10hFXN, we administered 1.8 × 1011, 5.7 × 1011, or 1.8 × 1012 gc/kg of AAVrh.10hFXN intravenously (IV) to muscle creatine kinase (mck)-Cre conditional knockout Fxn mice, a cardiac and skeletal FXN knockout model. The minimally effective dose was 5.7 × 1011 gc/kg, resulting in cardiac hFXN levels of 6.1 ± 4.2 ng/mg and a mild (p < 0.01 compared with phosphate-buffered saline controls) improvement in mortality. A dose of 1.8 × 1012 gc/kg resulted in cardiac hFXN levels of 33.7 ± 6.4 ng/mg, a significant improvement in ejection fraction and fractional shortening (p < 0.05, both comparisons) and a 21.5% improvement in mortality (p < 0.001). To determine if the significantly effective dose of 1.8 × 1012 gc/kg could achieve human FA heterozygote levels in a large animal, this dose was administered IV to nonhuman primates. After 12 weeks, the vector-expressed FXN in the heart was 17.8 ± 4.9 ng/mg, comparable to the target human levels. These data identify both minimally and significantly effective therapeutic doses that are clinically relevant for the treatment of the cardiac manifestations of FA.
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Affiliation(s)
| | - Monica Gertz
- Department of Genetic Medicine, New York, New York, USA
| | | | | | | | - Alvin Chen
- Department of Genetic Medicine, New York, New York, USA
| | - Vikrum Kooner
- Department of Genetic Medicine, New York, New York, USA
| | | | - Bishnu P. De
- Department of Genetic Medicine, New York, New York, USA
| | | | - Alain Borczuk
- Department of Pathology, Weill Cornell Medicine, New York, New York, USA
| | - Rodolfo J. Ricart Arbona
- Center for Comparative Medicine and Pathology, Memorial Sloan Kettering Cancer Center, Weill Cornell Medicine, New York, New York, USA
| | - Heather R. Martin
- Center for Comparative Medicine and Pathology, Memorial Sloan Kettering Cancer Center, Weill Cornell Medicine, New York, New York, USA
| | - Sebastien Monette
- Center for Comparative Medicine and Pathology, Memorial Sloan Kettering Cancer Center, Weill Cornell Medicine, New York, New York, USA
| | | | | | | | - Dolan Sondhi
- Department of Genetic Medicine, New York, New York, USA
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Profeta V, McIntyre K, Wells M, Park C, Lynch DR. Omaveloxolone: an activator of Nrf2 for the treatment of Friedreich ataxia. Expert Opin Investig Drugs 2023; 32:5-16. [PMID: 36708320 DOI: 10.1080/13543784.2023.2173063] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
INTRODUCTION Friedreich ataxia (FRDA) is a rare autosomal recessive degenerative disorder characterized by ataxia, dysarthria, diabetes, cardiomyopathy, scoliosis, and occasionally vision loss in late-stage disease. The discovery of the abnormal gene in FRDA and its product frataxin has provided insight into the pathophysiology and mechanisms of treatment. AREAS COVERED Although the neurologic phenotype of FRDA is well defined, there are currently no established pharmacological treatments. Omaveloxolone, a nuclear factor erythroid 2-related factor 2 (Nrf2) activator, is currently under review by the Food and Drug Administration (FDA) and has the potential to be the first approved treatment for FRDA. In the present report, we have reviewed the basic and clinical literature on Nrf2 deficiency in FRDA, and evidence for the benefit of omaveloxolone. EXPERT OPINION The present perspective suggests that omaveloxolone is a rational and efficacious therapy that is possibly disease modifying in treatment of FRDA.
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Affiliation(s)
- Victoria Profeta
- Departments of Pediatrics and Neurology, Children's Hospital of Philadelphia, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Kellie McIntyre
- Departments of Pediatrics and Neurology, Children's Hospital of Philadelphia, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - McKenzie Wells
- Departments of Pediatrics and Neurology, Children's Hospital of Philadelphia, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Courtney Park
- Departments of Pediatrics and Neurology, Children's Hospital of Philadelphia, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - David R Lynch
- Departments of Pediatrics and Neurology, Children's Hospital of Philadelphia, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
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Jama M, Margraf RL, Yu P, Reading NS, Bayrak-Toydemir P. A Comprehensive Triple-Repeat Primed PCR and a Long-Range PCR Agarose-Based Assay for Improved Genotyping of Guanine-Adenine-Adenine Repeats in Friedreich Ataxia. J Mol Diagn 2022; 24:915-923. [PMID: 35595154 DOI: 10.1016/j.jmoldx.2022.04.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2021] [Revised: 03/14/2022] [Accepted: 04/25/2022] [Indexed: 11/18/2022] Open
Abstract
Friedreich ataxia is a rare autosomal recessive, neuromuscular degenerative disease caused by an expansion of a trinucleotide [guanine-adenine-adenine (GAA)] repeat in intron 1 of the FXN gene. It is common in the White population, characterized by progressive gait and limb ataxia, lack of tendon reflexes in the legs, loss of position sense, and hypertrophic cardiomyopathy. Detection and genotyping of the trinucleotide repeat length is important for the diagnosis and prognosis of the disease. A two-tier genotyping assay with an improved triple-repeat primed PCR (TR-PCR) for alleles <200 GAA repeats (±1 to 5 repeats) and an agarose gel-based, long-range PCR (LR-PCR) assay to genotype expanded alleles >200 GAA repeats (±50 repeats) is described. Of the 1236 DNA samples tested using TR-PCR, 31 were identified to have expanded alleles >200 repeats and were reflexed to the LR-PCR procedure for confirmation and quantification. The TR-PCR assay described herein is a diagnostic genotyping assay that reduces the need for further testing. The LR-PCR component is a confirmatory test for true homozygous and heterozygous samples with normal and expanded alleles, as indicated by the TR-PCR assay. The use of this two-tier method offers a comprehensive evaluation to detect and genotype the smallest and largest number of GAA repeats, improving the classification of FXN alleles as normal, mutable normal, borderline, and expanded alleles.
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Affiliation(s)
- Mohamed Jama
- Associated Regional and University Pathologists (ARUP) Institute for Clinical and Experimental Pathology, University of Utah, Salt Lake City, Utah.
| | - Rebecca L Margraf
- Associated Regional and University Pathologists (ARUP) Institute for Clinical and Experimental Pathology, University of Utah, Salt Lake City, Utah
| | - Ping Yu
- ARUP Laboratories, University of Utah, Salt Lake City, Utah
| | - N Scott Reading
- Associated Regional and University Pathologists (ARUP) Institute for Clinical and Experimental Pathology, University of Utah, Salt Lake City, Utah; Department of Pathology, University of Utah, Salt Lake City, Utah
| | - Pinar Bayrak-Toydemir
- Associated Regional and University Pathologists (ARUP) Institute for Clinical and Experimental Pathology, University of Utah, Salt Lake City, Utah; Department of Pathology, University of Utah, Salt Lake City, Utah
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9
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Quatrana A, Morini E, Tiano F, Vancheri C, Panarello L, Romano S, Marcotulli C, Casali C, Mariotti C, Mongelli A, Fichera M, Rufini A, Condò I, Novelli G, Testi R, Amati F, Malisan F. Hsa-miR223-3p circulating level is upregulated in Friedreich's ataxia and inversely associated with HCLS1 associated protein X-1, HAX-1. Hum Mol Genet 2022; 31:2010-2022. [PMID: 35015850 DOI: 10.1093/hmg/ddac005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Revised: 12/15/2021] [Accepted: 01/04/2022] [Indexed: 11/12/2022] Open
Abstract
Frataxin (FXN) deficiency is responsible for Friedreich's ataxia (FRDA) in which, besides the characteristic features of spinocerebellar ataxia, two thirds of patients develop hypertrophic cardiomyopathy that often progresses to heart failure and premature death. Different mechanisms might underlie FRDA pathogenesis. Among them, the role of miRNAs deserves investigations. We carried out a miRNA PCR-array analysis of plasma samples of early-, intermediate- and late-onset FRDA groups, defining a set of 30 differentially expressed miRNAs. Hsa-miR223-3p is the only miRNA shared between the three patient groups and appears upregulated in all of them. The upregulation of hsa-miR223-3p was further validated in all enrolled patients (n = 37, Fc = +2.3; p < 0.0001). Using a Receiver Operating Characteristic (ROC) curve analysis, we quantified the predictive value of circulating hsa-miR223-3p for FRDA, obtaining an AUC (Area Under the ROC Curve) value of 0.835 (p < 0.0001) for all patients. Interestingly, we found a significant positive correlation between hsa-miR223-3p expression and cardiac parameters in typical FRDA patients (onset < 25 years). Moreover, a significant negative correlation between hsa-miR223-3p expression and HAX-1 (HCLS1 associated protein X-1) at mRNA and protein level was observed in all FRDA patients. In silico analyses suggested HAX-1 as a target gene of hsa-miR223-3p. Accordingly, we report that HAX-1 is negatively regulated by hsa-miR223-3p in cardiomyocytes (AC16) and neurons (SH-SY5Y), which are critically affected cell types in FRDA. This study describes for the first time the association between hsa-miR223-3p and HAX-1 expression in FRDA, thus supporting a potential role of this microRNA as non-invasive epigenetic biomarker for FRDA.
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Affiliation(s)
- Andrea Quatrana
- Laboratory of Signal Transduction, Dept. of Biomedicine and Prevention; University of Rome "Tor Vergata", 00133 Rome, Italy
| | - Elena Morini
- Section of Medical Genetics, Dept. of Biomedicine and Prevention, University of Rome "Tor Vergata", 00133 Rome, Italy
| | - Francesca Tiano
- Laboratory of Signal Transduction, Dept. of Biomedicine and Prevention; University of Rome "Tor Vergata", 00133 Rome, Italy.,Unit of Oncogenomics and Epigenetics, IRCCS Regina Elena National Cancer Institute, 00144 Rome, Italy
| | - Chiara Vancheri
- Section of Medical Genetics, Dept. of Biomedicine and Prevention, University of Rome "Tor Vergata", 00133 Rome, Italy
| | - Luca Panarello
- Laboratory of Signal Transduction, Dept. of Biomedicine and Prevention; University of Rome "Tor Vergata", 00133 Rome, Italy
| | - Silvia Romano
- Neurosciences, Mental Health and Sensory Organs (NESMOS) Department, Faculty of Medicine and Psychology, Sapienza University, 00189 Rome, Italy
| | | | - Carlo Casali
- Dept. of Medical Surgical Sciences and Biotechnologies, Polo Pontino-Sapienza University of Rome, 04100 Latina, Italy
| | - Caterina Mariotti
- Unit of Medical Genetics and Neurogenetics, Fondazione IRCCS Istituto Neurologico Carlo Besta, 20133, Milan, Italy
| | - Alessia Mongelli
- Unit of Medical Genetics and Neurogenetics, Fondazione IRCCS Istituto Neurologico Carlo Besta, 20133, Milan, Italy
| | - Mario Fichera
- Unit of Medical Genetics and Neurogenetics, Fondazione IRCCS Istituto Neurologico Carlo Besta, 20133, Milan, Italy
| | - Alessandra Rufini
- Laboratory of Signal Transduction, Dept. of Biomedicine and Prevention; University of Rome "Tor Vergata", 00133 Rome, Italy.,Fratagene Therapeutics Srl, Rome, 00144 Rome, Italy.,Saint Camillus International University of Health and Medical Sciences, 00131 Rome, Italy
| | - Ivano Condò
- Laboratory of Signal Transduction, Dept. of Biomedicine and Prevention; University of Rome "Tor Vergata", 00133 Rome, Italy
| | - Giuseppe Novelli
- Section of Medical Genetics, Dept. of Biomedicine and Prevention, University of Rome "Tor Vergata", 00133 Rome, Italy.,Neuromed Institute, IRCCS, 86077 Pozzilli, Italy
| | - Roberto Testi
- Laboratory of Signal Transduction, Dept. of Biomedicine and Prevention; University of Rome "Tor Vergata", 00133 Rome, Italy.,Fratagene Therapeutics Srl, Rome, 00144 Rome, Italy
| | - Francesca Amati
- Section of Medical Genetics, Dept. of Biomedicine and Prevention, University of Rome "Tor Vergata", 00133 Rome, Italy.,Department for the Promotion of Human Science and Quality of Life, University San Raffaele, 00166 Rome, Italy
| | - Florence Malisan
- Laboratory of Signal Transduction, Dept. of Biomedicine and Prevention; University of Rome "Tor Vergata", 00133 Rome, Italy
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10
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Nethisinghe S, Kesavan M, Ging H, Labrum R, Polke JM, Islam S, Garcia-Moreno H, Callaghan MF, Cavalcanti F, Pook MA, Giunti P. Interruptions of the FXN GAA Repeat Tract Delay the Age at Onset of Friedreich's Ataxia in a Location Dependent Manner. Int J Mol Sci 2021; 22:7507. [PMID: 34299126 PMCID: PMC8307455 DOI: 10.3390/ijms22147507] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2021] [Revised: 06/12/2021] [Accepted: 06/18/2021] [Indexed: 12/03/2022] Open
Abstract
Friedreich's ataxia (FRDA) is a comparatively rare autosomal recessive neurological disorder primarily caused by the homozygous expansion of a GAA trinucleotide repeat in intron 1 of the FXN gene. The repeat expansion causes gene silencing that results in deficiency of the frataxin protein leading to mitochondrial dysfunction, oxidative stress and cell death. The GAA repeat tract in some cases may be impure with sequence variations called interruptions. It has previously been observed that large interruptions of the GAA repeat tract, determined by abnormal MboII digestion, are very rare. Here we have used triplet repeat primed PCR (TP PCR) assays to identify small interruptions at the 5' and 3' ends of the GAA repeat tract through alterations in the electropherogram trace signal. We found that contrary to large interruptions, small interruptions are more common, with 3' interruptions being most frequent. Based on detection of interruptions by TP PCR assay, the patient cohort (n = 101) was stratified into four groups: 5' interruption, 3' interruption, both 5' and 3' interruptions or lacking interruption. Those patients with 3' interruptions were associated with shorter GAA1 repeat tracts and later ages at disease onset. The age at disease onset was modelled by a group-specific exponential decay model. Based on this modelling, a 3' interruption is predicted to delay disease onset by approximately 9 years relative to those lacking 5' and 3' interruptions. This highlights the key role of interruptions at the 3' end of the GAA repeat tract in modulating the disease phenotype and its impact on prognosis for the patient.
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Affiliation(s)
- Suran Nethisinghe
- Ataxia Centre, Department of Clinical and Movement Neurosciences, UCL Queen Square Institute of Neurology, Queen Square, London WC1N 3BG, UK; (S.N.); (M.K.); (H.G.); (H.G.-M.)
| | - Maheswaran Kesavan
- Ataxia Centre, Department of Clinical and Movement Neurosciences, UCL Queen Square Institute of Neurology, Queen Square, London WC1N 3BG, UK; (S.N.); (M.K.); (H.G.); (H.G.-M.)
| | - Heather Ging
- Ataxia Centre, Department of Clinical and Movement Neurosciences, UCL Queen Square Institute of Neurology, Queen Square, London WC1N 3BG, UK; (S.N.); (M.K.); (H.G.); (H.G.-M.)
| | - Robyn Labrum
- Neurogenetics Service, Rare and Inherited Disease Laboratory, London North Genomic Laboratory Hub, Great Ormond Street Hospital for Children NHS Foundation Trust, London WC1N 3BH, UK; (R.L.); (J.M.P.)
| | - James M. Polke
- Neurogenetics Service, Rare and Inherited Disease Laboratory, London North Genomic Laboratory Hub, Great Ormond Street Hospital for Children NHS Foundation Trust, London WC1N 3BH, UK; (R.L.); (J.M.P.)
| | - Saiful Islam
- UCL Queen Square Institute of Neurology, London WC1N 3BG, UK;
| | - Hector Garcia-Moreno
- Ataxia Centre, Department of Clinical and Movement Neurosciences, UCL Queen Square Institute of Neurology, Queen Square, London WC1N 3BG, UK; (S.N.); (M.K.); (H.G.); (H.G.-M.)
| | - Martina F. Callaghan
- Wellcome Centre for Human Neuroimaging, UCL Queen Square Institute of Neurology, University College London, London WC1N 3AR, UK;
| | - Francesca Cavalcanti
- Institute for Biomedical Research and Innovation (IRIB), Italian National Research Council (CNR), 87050 Mangone, Italy;
| | - Mark A. Pook
- Ataxia Research Group, Division of Biosciences, Department of Life Sciences, College of Health and Life Sciences, Brunel University London, Uxbridge UB8 3PH, UK;
- Synthetic Biology Theme, Institute of Environment, Health and Societies, Brunel University London, Uxbridge UB8 3PH, UK
| | - Paola Giunti
- Ataxia Centre, Department of Clinical and Movement Neurosciences, UCL Queen Square Institute of Neurology, Queen Square, London WC1N 3BG, UK; (S.N.); (M.K.); (H.G.); (H.G.-M.)
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11
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Rodden LN, Chutake YK, Gilliam K, Lam C, Soragni E, Hauser L, Gilliam M, Wiley G, Anderson MP, Gottesfeld JM, Lynch DR, Bidichandani SI. Methylated and unmethylated epialleles support variegated epigenetic silencing in Friedreich ataxia. Hum Mol Genet 2021; 29:3818-3829. [PMID: 33432325 PMCID: PMC7861014 DOI: 10.1093/hmg/ddaa267] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2020] [Revised: 12/01/2020] [Accepted: 12/09/2020] [Indexed: 12/20/2022] Open
Abstract
Friedreich ataxia (FRDA) is typically caused by homozygosity for an expanded GAA triplet-repeat in intron 1 of the FXN gene, which results in transcriptional deficiency via epigenetic silencing. Most patients are homozygous for alleles containing > 500 triplets, but a subset (~20%) have at least one expanded allele with < 500 triplets and a distinctly milder phenotype. We show that in FRDA DNA methylation spreads upstream from the expanded repeat, further than previously recognized, and establishes an FRDA-specific region of hypermethylation in intron 1 (~90% in FRDA versus < 10% in non-FRDA) as a novel epigenetic signature. The hypermethylation of this differentially methylated region (FRDA-DMR) was observed in a variety of patient-derived cells; it significantly correlated with FXN transcriptional deficiency and age of onset, and it reverted to the non-disease state in isogenically corrected induced pluripotent stem cell (iPSC)-derived neurons. Bisulfite deep sequencing of the FRDA-DMR in peripheral blood mononuclear cells from 73 FRDA patients revealed considerable intra-individual epiallelic variability, including fully methylated, partially methylated, and unmethylated epialleles. Although unmethylated epialleles were rare (median = 0.33%) in typical patients homozygous for long GAA alleles with > 500 triplets, a significantly higher prevalence of unmethylated epialleles (median = 9.8%) was observed in patients with at least one allele containing < 500 triplets, less severe FXN deficiency (>20%) and later onset (>15 years). The higher prevalence in mild FRDA of somatic FXN epialleles devoid of DNA methylation is consistent with variegated epigenetic silencing mediated by expanded triplet-repeats. The proportion of unsilenced somatic FXN genes is an unrecognized phenotypic determinant in FRDA and has implications for the deployment of effective therapies.
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Affiliation(s)
- Layne N Rodden
- Department of Pediatrics, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
- Oklahoma Center for Neuroscience, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Yogesh K Chutake
- Department of Pediatrics, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Kaitlyn Gilliam
- Department of Pediatrics, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Christina Lam
- Department of Pediatrics, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Elisabetta Soragni
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, USA
| | - Lauren Hauser
- Division of Neurology, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Matthew Gilliam
- Department of Electrical and Computer Engineering, University of Oklahoma, Norman, OK, USA
| | - Graham Wiley
- Arthritis and Clinical Immunology Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, USA
| | - Michael P Anderson
- Department of Biostatistics and Epidemiology, Hudson College of Public Health, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Joel M Gottesfeld
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, USA
| | - David R Lynch
- Division of Neurology, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Sanjay I Bidichandani
- Department of Pediatrics, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
- Oklahoma Center for Neuroscience, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
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12
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Expanding the genotype-phenotype correlation of childhood sensory polyneuropathy of genetic origin. Sci Rep 2020; 10:16184. [PMID: 32999401 PMCID: PMC7528082 DOI: 10.1038/s41598-020-73219-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Accepted: 09/14/2020] [Indexed: 01/02/2023] Open
Abstract
Pure sensory polyneuropathy of genetic origin is rare in childhood and hence important to document the clinical and genetic etiologies from single or multi-center studies. This study focuses on a retrospective chart-review of neurological examinations and genetic and electrodiagnostic data of confirmed sensory polyneuropathy in subjects at a tertiary-care Children's Hospital from 2013 to 2019. Twenty subjects were identified and included. Neurological examination and electrodiagnostic testing showed gait-difficulties, absent tendon reflexes, decreased joint-position, positive Romberg's test and large fiber sensory polyneuropathy on sensory nerve conduction studies in all patients associated with lower-extremity spasticity (6), cardiac abnormalities or cardiomyopathy (5), developmental delay (4), scoliosis (3), epilepsy (3) and hearing-difficulties (2). Confirmation of genetic diagnosis in correlation with clinical presentation was obtained in all cases (COX20 n = 2, HADHA n = 2, POLG n = 1, FXN n = 4, ATXN2 n = 3, ATM n = 3, GAN n = 2, SPG7 n = 1, ZFYVE26 n = 1, FH n = 1). Our single-center study shows genetic sensory polyneuropathies associated with progressive neurodegenerative disorders such as mitochondrial ataxia, Friedreich ataxia, spinocerebellar ataxia type 2, ataxia telangiectasia, spastic paraplegia, giant axonal neuropathy, and fumarate hydratase deficiency. We also present our cohort data in light of clinical features reported for each gene-specific disease subtype in the literature and highlight the importance of genetic testing in the relevant clinical context of electrophysiological findings of peripheral sensory polyneuropathy.
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13
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Mystery of Expansion: DNA Metabolism and Unstable Repeats. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020; 1241:101-124. [PMID: 32383118 DOI: 10.1007/978-3-030-41283-8_7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Abstract
The mammalian genome mostly contains repeated sequences. Some of these repeats are in the regulatory elements of genes, and their instability, particularly the propensity to change the repeat unit number, is responsible for 36 well-known neurodegenerative human disorders. The mechanism of repeat expansion has been an unsolved question for more than 20 years. There are a few hypotheses describing models of mutation development. Every hypothesis is based on assumptions about unusual secondary structures that violate DNA metabolism processes in the cell. Some models are based on replication errors, and other models are based on mismatch repair or base excision repair errors. Additionally, it has been shown that epigenetic regulation of gene expression can influence the probability and frequency of expansion. In this review, we consider the molecular bases of repeat expansion disorders and discuss possible mechanisms of repeat expansion during cell metabolism.
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14
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Khristich AN, Mirkin SM. On the wrong DNA track: Molecular mechanisms of repeat-mediated genome instability. J Biol Chem 2020; 295:4134-4170. [PMID: 32060097 PMCID: PMC7105313 DOI: 10.1074/jbc.rev119.007678] [Citation(s) in RCA: 141] [Impact Index Per Article: 35.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Expansions of simple tandem repeats are responsible for almost 50 human diseases, the majority of which are severe, degenerative, and not currently treatable or preventable. In this review, we first describe the molecular mechanisms of repeat-induced toxicity, which is the connecting link between repeat expansions and pathology. We then survey alternative DNA structures that are formed by expandable repeats and review the evidence that formation of these structures is at the core of repeat instability. Next, we describe the consequences of the presence of long structure-forming repeats at the molecular level: somatic and intergenerational instability, fragility, and repeat-induced mutagenesis. We discuss the reasons for gender bias in intergenerational repeat instability and the tissue specificity of somatic repeat instability. We also review the known pathways in which DNA replication, transcription, DNA repair, and chromatin state interact and thereby promote repeat instability. We then discuss possible reasons for the persistence of disease-causing DNA repeats in the genome. We describe evidence suggesting that these repeats are a payoff for the advantages of having abundant simple-sequence repeats for eukaryotic genome function and evolvability. Finally, we discuss two unresolved fundamental questions: (i) why does repeat behavior differ between model systems and human pedigrees, and (ii) can we use current knowledge on repeat instability mechanisms to cure repeat expansion diseases?
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Affiliation(s)
| | - Sergei M Mirkin
- Department of Biology, Tufts University, Medford, Massachusetts 02155.
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15
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Jackson JL, Finch NA, Baker MC, Kachergus JM, DeJesus-Hernandez M, Pereira K, Christopher E, Prudencio M, Heckman MG, Thompson EA, Dickson DW, Shah J, Oskarsson B, Petrucelli L, Rademakers R, van Blitterswijk M. Elevated methylation levels, reduced expression levels, and frequent contractions in a clinical cohort of C9orf72 expansion carriers. Mol Neurodegener 2020; 15:7. [PMID: 32000838 PMCID: PMC6993399 DOI: 10.1186/s13024-020-0359-8] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Accepted: 01/14/2020] [Indexed: 02/06/2023] Open
Abstract
Background A repeat expansion in the C9orf72-SMCR8 complex subunit (C9orf72) is the most common genetic cause of two debilitating neurodegenerative diseases: amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Currently, much remains unknown about which variables may modify these diseases. We sought to investigate associations between C9orf72 promoter methylation, RNA expression levels, and repeat length, their potential effects on disease features, as well as changes over time and within families. Methods All samples were obtained through the ALS Center at Mayo Clinic Florida. Our primary cohort included 75 unrelated patients with an expanded C9orf72 repeat, 33 patients who did not possess this expansion, and 20 control subjects without neurodegenerative diseases. Additionally, 67 members from 17 independent C9orf72 families were selected of whom 33 harbored this expansion. Longitudinally collected samples were available for 35 C9orf72 expansion carriers. To increase our understanding of C9orf72-related diseases, we performed quantitative methylation-sensitive restriction enzyme-based assays, digital molecular barcoding, quantitative real-time PCR, and Southern blotting. Results In our primary cohort, higher methylation levels were observed in patients with a C9orf72 repeat expansion than in patients without this expansion (p = 1.7e-13) or in control subjects (p = 3.3e-07). Moreover, we discovered that an increase in methylation levels was associated with a decrease in total C9orf72 transcript levels (p = 5.5e-05). These findings aligned with our observation that C9orf72 expansion carriers had lower expression levels of total C9orf72 transcripts than patients lacking this expansion (p = 3.7e-07) or control subjects (p = 9.1e-05). We also detected an elevation of transcripts containing intron 1a (upstream of the repeat) in patients carrying a C9orf72 repeat expansion compared to (disease) controls (p ≤ 0.01), an indication of abortive transcripts and/or a switch in transcription start site usage. While methylation and expression levels were relatively stable over time, fluctuations were seen in repeat length. Interestingly, contractions occurred frequently in parent-offspring transmissions (> 50%), especially in paternal transmissions. Furthermore, smaller repeat lengths were detected in currently unaffected individuals than in affected individuals (p = 8.9e-04) and they were associated with an earlier age at collection (p = 0.008). Conclusions In blood from C9orf72 expansion carriers, we found elevated methylation levels, reduced expression levels, and unstable expansions that tend to contract in successive generations, arguing against anticipation.
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Affiliation(s)
- Jazmyne L Jackson
- Department of Neuroscience, Mayo Clinic, 4500 San Pablo Road, Jacksonville, FL, 32224, USA
| | - NiCole A Finch
- Department of Neuroscience, Mayo Clinic, 4500 San Pablo Road, Jacksonville, FL, 32224, USA
| | - Matthew C Baker
- Department of Neuroscience, Mayo Clinic, 4500 San Pablo Road, Jacksonville, FL, 32224, USA
| | - Jennifer M Kachergus
- Department of Cancer Biology, Mayo Clinic, 4500 San Pablo Road, Jacksonville, FL, 32224, USA
| | | | - Kimberly Pereira
- Department of Neuroscience, Mayo Clinic, 4500 San Pablo Road, Jacksonville, FL, 32224, USA
| | - Elizabeth Christopher
- Department of Neuroscience, Mayo Clinic, 4500 San Pablo Road, Jacksonville, FL, 32224, USA
| | - Mercedes Prudencio
- Department of Neuroscience, Mayo Clinic, 4500 San Pablo Road, Jacksonville, FL, 32224, USA
| | - Michael G Heckman
- Division of Biomedical Statistics and Informatics, Mayo Clinic, 4500 San Pablo Road, Jacksonville, FL, 32224, USA
| | - E Aubrey Thompson
- Department of Cancer Biology, Mayo Clinic, 4500 San Pablo Road, Jacksonville, FL, 32224, USA
| | - Dennis W Dickson
- Department of Neuroscience, Mayo Clinic, 4500 San Pablo Road, Jacksonville, FL, 32224, USA
| | - Jaimin Shah
- Department of Neurology, Mayo Clinic, 4500 San Pablo Road, Jacksonville, FL, 32224, USA
| | - Björn Oskarsson
- Department of Neurology, Mayo Clinic, 4500 San Pablo Road, Jacksonville, FL, 32224, USA
| | - Leonard Petrucelli
- Department of Neuroscience, Mayo Clinic, 4500 San Pablo Road, Jacksonville, FL, 32224, USA
| | - Rosa Rademakers
- Department of Neuroscience, Mayo Clinic, 4500 San Pablo Road, Jacksonville, FL, 32224, USA.
| | - Marka van Blitterswijk
- Department of Neuroscience, Mayo Clinic, 4500 San Pablo Road, Jacksonville, FL, 32224, USA.
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16
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Left ventricular structural and functional changes in Friedreich ataxia - Relationship with body size, sex, age and genetic severity. PLoS One 2019; 14:e0225147. [PMID: 31721791 PMCID: PMC6853335 DOI: 10.1371/journal.pone.0225147] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Accepted: 10/29/2019] [Indexed: 12/30/2022] Open
Abstract
Introduction Although a concentric pattern of left ventricular (LV) geometry appears to be common in Friedreich ataxia (FRDA), there is no accepted method for diagnosing LV abnormalities in FRDA, sex and body size have often not been taken into consideration, and it has not been clear whether children and adults should be classified using the same criteria. The aim of this study was to better define the LV geometric changes in FRDA with respect to sex, body size and subject age, and to investigate the relationship of LV changes with genetic severity, as assessed by GAA repeat length within the shorter allele of the FXN gene (GAA1). Methods Echocardiography was performed in 216 subjects (68 children, 148 adults), measurements were made at end-diastole of LV internal diameter (LVEDID), septal wall thickness (SWT), LV length (LVEDL) and LV volume (LVEDV), and calculations were made of relative wall thickness (RWT), LV mass and LV ejection fraction (LVEF). Results The most common LV abnormalities in both adults and children with FRDA were increases in RWT and age-normalized RWT. In adults with a normal LVEF, all LV variables other than RWT were larger in males independent of body surface area (BSA), and all LV variables other than SWT and RWT were positively correlated with BSA. After adjustment for sex and BSA, GAA1 was a positive correlate of SWT and RWT (but not of LV mass), and was an inverse correlate of LVEDID, LVEDL and LVEDV. In children with a normal LVEF, SWT, LV mass and LVEDL were larger in males than females after adjusting for BSA, and in combination with sex, BSA was a positive correlate of all the LV variables except SWT and RWT. In children there were no correlations of GAA1 with any of the LV variables. Conclusion In FRDA, increases in RWT and age-normalized RWT are the most frequent LV structural abnormalities, sex and body size are important determinants of most other LV structural variables in both children and adults, and increased genetic severity is associated with a smaller left ventricle and increased LV wall thickness in adults, but not associated with LV size or wall thickness in children.
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17
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Naruse H, Takahashi Y, Ishiura H, Matsukawa T, Mitsui J, Ichikawa Y, Hamada M, Shimizu J, Goto J, Toda T, Tsuji S. Prominent Spasticity and Hyperreflexia of the Legs in a Nepalese Patient with Friedreich Ataxia. Intern Med 2019; 58:2865-2869. [PMID: 31178521 PMCID: PMC6815894 DOI: 10.2169/internalmedicine.2953-19] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Accepted: 03/26/2019] [Indexed: 11/06/2022] Open
Abstract
Friedreich ataxia (FRDA) is an autosomal recessive spinocerebellar ataxia caused by mutations of FXN. Hypotonus and hyporeflexia of the lower extremities are observed in most FRDA patients. Patients with hyperreflexia, called Friedreich ataxia with retained reflexes (FARR), have also been identified. We herein report the case of a 16-year-old Nepalese boy presenting with early-onset ataxia with prominent spasticity and hyperreflexia of the legs. Mutational analyses established the diagnosis of FRDA presenting as FARR. A haplotype analysis revealed that expanded alleles of the patient shared a common haplotype with Indian and European FRDA patients, suggesting that the mutation descended from a common founder.
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Affiliation(s)
- Hiroya Naruse
- Department of Neurology, Graduate School of Medicine, The University of Tokyo, Japan
| | - Yuji Takahashi
- Department of Neurology, National Center Hospital, National Center of Neurology and Psychiatry, Japan
| | - Hiroyuki Ishiura
- Department of Neurology, Graduate School of Medicine, The University of Tokyo, Japan
| | - Takashi Matsukawa
- Department of Neurology, Graduate School of Medicine, The University of Tokyo, Japan
- Department of Molecular Neurology, Graduate School of Medicine, The University of Tokyo, Japan
| | - Jun Mitsui
- Department of Neurology, Graduate School of Medicine, The University of Tokyo, Japan
- Department of Molecular Neurology, Graduate School of Medicine, The University of Tokyo, Japan
| | - Yaeko Ichikawa
- Department of Neurology, Faculty of Medicine, Kyorin University, Japan
| | - Masashi Hamada
- Department of Neurology, Graduate School of Medicine, The University of Tokyo, Japan
| | - Jun Shimizu
- Department of Neurology, Graduate School of Medicine, The University of Tokyo, Japan
| | - Jun Goto
- Department of Neurology, International University of Health and Welfare Mita Hospital, Japan
| | - Tatsushi Toda
- Department of Neurology, Graduate School of Medicine, The University of Tokyo, Japan
| | - Shoji Tsuji
- Department of Molecular Neurology, Graduate School of Medicine, The University of Tokyo, Japan
- International University of Health and Welfare, Japan
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18
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Delatycki MB, Bidichandani SI. Friedreich ataxia- pathogenesis and implications for therapies. Neurobiol Dis 2019; 132:104606. [PMID: 31494282 DOI: 10.1016/j.nbd.2019.104606] [Citation(s) in RCA: 64] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Revised: 08/08/2019] [Accepted: 09/04/2019] [Indexed: 01/01/2023] Open
Abstract
Friedreich ataxia is the most common of the hereditary ataxias. It is due to homozygous/compound heterozygous mutations in FXN. This gene encodes frataxin, a protein largely localized to mitochondria. In about 96% of affected individuals there is homozygosity for a GAA repeat expansion in intron 1 of the FXN gene. Studies of people with Friedreich ataxia and of animal and cell models, have provided much insight into the pathogenesis of this disorder. The expanded GAA repeat leads to transcriptional deficiency of the FXN gene. The consequent deficiency of frataxin protein leads to reduced iron-sulfur cluster biogenesis and mitochondrial ATP production, elevated mitochondrial iron, and oxidative stress. More recently, a role for inflammation has emerged as being important in the pathogenesis of Friedreich ataxia. These findings have led to a number of potential therapies that have been subjected to clinical trials or are being developed toward human studies. Therapies that have been proposed include pharmaceuticals that increase frataxin levels, protein and gene replacement therapies, antioxidants, iron chelators and modulators of inflammation. Whilst no therapies have yet been approved for Friedreich ataxia, there is much optimism that the advances in the understanding of the pathogenesis of this disorder since the discovery its genetic basis, will result in approved disease modifying therapies in the near future.
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Affiliation(s)
- Martin B Delatycki
- Bruce Lefroy Centre, Murdoch Children's Research Institute, Parkville, Victoria, Australia; Victorian Clinical Genetics Services, Parkville, Victoria, Australia; Department of Paediatrics, University of Melbourne, Parkville, Victoria, Australia.
| | - Sanjay I Bidichandani
- Department of Pediatrics, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA; Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA; Oklahoma Center for Neuroscience, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
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19
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Llorens JV, Soriano S, Calap-Quintana P, Gonzalez-Cabo P, Moltó MD. The Role of Iron in Friedreich's Ataxia: Insights From Studies in Human Tissues and Cellular and Animal Models. Front Neurosci 2019; 13:75. [PMID: 30833885 PMCID: PMC6387962 DOI: 10.3389/fnins.2019.00075] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Accepted: 01/23/2019] [Indexed: 12/12/2022] Open
Abstract
Friedreich’s ataxia (FRDA) is a rare early-onset degenerative disease that affects both the central and peripheral nervous systems, and other extraneural tissues, mainly the heart and endocrine pancreas. This disorder progresses as a mixed sensory and cerebellar ataxia, primarily disturbing the proprioceptive pathways in the spinal cord, peripheral nerves and nuclei of the cerebellum. FRDA is an inherited disease with an autosomal recessive pattern caused by an insufficient amount of the nuclear-encoded mitochondrial protein frataxin, which is an essential and highly evolutionary conserved protein whose deficit results in iron metabolism dysregulation and mitochondrial dysfunction. The first experimental evidence connecting frataxin with iron homeostasis came from Saccharomyces cerevisiae; iron accumulates in the mitochondria of yeast with deletion of the frataxin ortholog gene. This finding was soon linked to previous observations of iron deposits in the hearts of FRDA patients and was later reported in animal models of the disease. Despite advances made in the understanding of FRDA pathophysiology, the role of iron in this disease has not yet been completely clarified. Some of the questions still unresolved include the molecular mechanisms responsible for the iron accumulation and iron-mediated toxicity. Here, we review the contribution of the cellular and animal models of FRDA and relevance of the studies using FRDA patient samples to gain knowledge about these issues. Mechanisms of mitochondrial iron overload are discussed considering the potential roles of frataxin in the major mitochondrial metabolic pathways that use iron. We also analyzed the effect of iron toxicity on neuronal degeneration in FRDA by reactive oxygen species (ROS)-dependent and ROS-independent mechanisms. Finally, therapeutic strategies based on the control of iron toxicity are considered.
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Affiliation(s)
- José Vicente Llorens
- Department of Genetics, Faculty of Biological Sciences, University of Valencia, Valencia, Spain.,Unit for Psychiatry and Neurodegenerative Diseases, Biomedical Research Institute INCLIVA, Valencia, Spain
| | - Sirena Soriano
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, United States.,Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, United States
| | - Pablo Calap-Quintana
- Department of Genetics, Faculty of Biological Sciences, University of Valencia, Valencia, Spain.,Unit for Psychiatry and Neurodegenerative Diseases, Biomedical Research Institute INCLIVA, Valencia, Spain
| | - Pilar Gonzalez-Cabo
- Department of Physiology, Faculty of Medicine and Dentistry, University of Valencia, Valencia, Spain.,Center of Biomedical Network Research on Rare Diseases CIBERER, Valencia, Spain.,Associated Unit for Rare Diseases INCLIVA-CIPF, Biomedical Research Institute INCLIVA, Valencia, Spain
| | - María Dolores Moltó
- Department of Genetics, Faculty of Biological Sciences, University of Valencia, Valencia, Spain.,Unit for Psychiatry and Neurodegenerative Diseases, Biomedical Research Institute INCLIVA, Valencia, Spain.,Center of Biomedical Network Research on Mental Health CIBERSAM, Valencia, Spain
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20
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Zeitlberger A, Ging H, Nethisinghe S, Giunti P. Advances in the understanding of hereditary ataxia – implications for future patients. Expert Opin Orphan Drugs 2018. [DOI: 10.1080/21678707.2018.1444477] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Affiliation(s)
- Anna Zeitlberger
- Department of Molecular Neuroscience, UCL Institute of Neurology, London, UK
| | - Heather Ging
- Department of Molecular Neuroscience, UCL Institute of Neurology, London, UK
| | - Suran Nethisinghe
- Department of Molecular Neuroscience, UCL Institute of Neurology, London, UK
| | - Paola Giunti
- Department of Molecular Neuroscience, UCL, Institute of Neurology, National Hospital for Neurology and Neurosurgery, London, UK
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21
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Kemp K, Dey R, Cook A, Scolding N, Wilkins A. Mesenchymal Stem Cell-Derived Factors Restore Function to Human Frataxin-Deficient Cells. CEREBELLUM (LONDON, ENGLAND) 2017; 16:840-851. [PMID: 28456899 PMCID: PMC5498643 DOI: 10.1007/s12311-017-0860-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Friedreich's ataxia is an inherited neurological disorder characterised by mitochondrial dysfunction and increased susceptibility to oxidative stress. At present, no therapy has been shown to reduce disease progression. Strategies being trialled to treat Friedreich's ataxia include drugs that improve mitochondrial function and reduce oxidative injury. In addition, stem cells have been investigated as a potential therapeutic approach. We have used siRNA-induced knockdown of frataxin in SH-SY5Y cells as an in vitro cellular model for Friedreich's ataxia. Knockdown of frataxin protein expression to levels detected in patients with the disorder was achieved, leading to decreased cellular viability, increased susceptibility to hydrogen peroxide-induced oxidative stress, dysregulation of key anti-oxidant molecules and deficiencies in both cell proliferation and differentiation. Bone marrow stem cells are being investigated extensively as potential treatments for a wide range of neurological disorders, including Friedreich's ataxia. The potential neuroprotective effects of bone marrow-derived mesenchymal stem cells were therefore studied using our frataxin-deficient cell model. Soluble factors secreted by mesenchymal stem cells protected against cellular changes induced by frataxin deficiency, leading to restoration in frataxin levels and anti-oxidant defences, improved survival against oxidative stress and stimulated both cell proliferation and differentiation down the Schwann cell lineage. The demonstration that mesenchymal stem cell-derived factors can restore cellular homeostasis and function to frataxin-deficient cells further suggests that they may have potential therapeutic benefits for patients with Friedreich's ataxia.
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Affiliation(s)
- Kevin Kemp
- Multiple Sclerosis and Stem Cell Group, School of Clinical Sciences, Clinical Neurosciences office, University of Bristol, 1st floor, Learning and Research building, Southmead Hospital, Bristol, BS10 5NB, UK.
| | - Rimi Dey
- Multiple Sclerosis and Stem Cell Group, School of Clinical Sciences, Clinical Neurosciences office, University of Bristol, 1st floor, Learning and Research building, Southmead Hospital, Bristol, BS10 5NB, UK
| | - Amelia Cook
- Multiple Sclerosis and Stem Cell Group, School of Clinical Sciences, Clinical Neurosciences office, University of Bristol, 1st floor, Learning and Research building, Southmead Hospital, Bristol, BS10 5NB, UK
| | - Neil Scolding
- Multiple Sclerosis and Stem Cell Group, School of Clinical Sciences, Clinical Neurosciences office, University of Bristol, 1st floor, Learning and Research building, Southmead Hospital, Bristol, BS10 5NB, UK
| | - Alastair Wilkins
- Multiple Sclerosis and Stem Cell Group, School of Clinical Sciences, Clinical Neurosciences office, University of Bristol, 1st floor, Learning and Research building, Southmead Hospital, Bristol, BS10 5NB, UK
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22
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Soriano S, Calap-Quintana P, Llorens JV, Al-Ramahi I, Gutiérrez L, Martínez-Sebastián MJ, Botas J, Moltó MD. Metal Homeostasis Regulators Suppress FRDA Phenotypes in a Drosophila Model of the Disease. PLoS One 2016; 11:e0159209. [PMID: 27433942 PMCID: PMC4951068 DOI: 10.1371/journal.pone.0159209] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Accepted: 06/28/2016] [Indexed: 11/19/2022] Open
Abstract
Friedreich's ataxia (FRDA), the most commonly inherited ataxia in populations of European origin, is a neurodegenerative disorder caused by a decrease in frataxin levels. One of the hallmarks of the disease is the accumulation of iron in several tissues including the brain, and frataxin has been proposed to play a key role in iron homeostasis. We found that the levels of zinc, copper, manganese and aluminum were also increased in a Drosophila model of FRDA, and that copper and zinc chelation improve their impaired motor performance. By means of a candidate genetic screen, we identified that genes implicated in iron, zinc and copper transport and metal detoxification can restore frataxin deficiency-induced phenotypes. Taken together, these results demonstrate that the metal dysregulation in FRDA includes other metals besides iron, therefore providing a new set of potential therapeutic targets.
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Affiliation(s)
- Sirena Soriano
- Department of Genetics, University of Valencia, Burjassot, Valencia, Spain
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | | | | | - Ismael Al-Ramahi
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Lucía Gutiérrez
- Department of Biomaterials and Bioinspired Materials, Instituto de Ciencia de Materiales de Madrid/CSIC, Madrid, Spain
| | | | - Juan Botas
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - María Dolores Moltó
- Department of Genetics, University of Valencia, Burjassot, Valencia, Spain
- CIBERSAM, INCLIVA, Valencia, Spain
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23
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Poburski D, Boerner JB, Koenig M, Ristow M, Thierbach R. Time-resolved functional analysis of acute impairment of frataxin expression in an inducible cell model of Friedreich ataxia. Biol Open 2016; 5:654-61. [PMID: 27106929 PMCID: PMC4874353 DOI: 10.1242/bio.017004] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Friedreich ataxia is a neurodegenerative disease caused by a GAA triplet repeat expansion in the first intron of the frataxin gene, which results in reduced expression levels of the corresponding protein. Despite numerous animal and cellular models, therapeutic options that mechanistically address impaired frataxin expression are lacking. Here, we have developed a new mammalian cell model employing the Cre/loxP recombination system to induce a homozygous or heterozygous frataxin knockout in mouse embryonic fibroblasts. Induction of Cre-mediated disruption by tamoxifen was successfully tested on RNA and protein levels. After loss of frataxin protein, cell division, aconitase activity and oxygen consumption rates were found to be decreased, while ROS production was increased in the homozygous state. By contrast, in the heterozygous state no such changes were observed. A time-resolved analysis revealed the loss of aconitase activity as an initial event after induction of complete frataxin deficiency, followed by secondarily elevated ROS production and a late increase in iron content. Initial impairments of oxygen consumption and ATP production were found to be compensated in the late state and seemed to play a minor role in Friedreich ataxia pathophysiology. In conclusion and as predicted from its proposed role in iron sulfur cluster (ISC) biosynthesis, disruption of frataxin primarily causes impaired function of ISC-containing enzymes, whereas other consequences, including elevated ROS production and iron accumulation, appear secondary. These parameters and the robustness of the newly established system may additionally be used for a time-resolved study of pharmacological candidates in a HTS manner. Summary: The use of a new mammalian cell model with inducible homozygous and heterozygous frataxin knockout allows new insights into the chronology and causes of the disease Friedreich ataxia.
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Affiliation(s)
- Dörte Poburski
- Institute of Nutrition, Friedrich Schiller University (FSU) Jena, Dornburgerstraße 24, Jena D-07743, Germany
| | - Josefine Barbara Boerner
- Institute of Nutrition, Friedrich Schiller University (FSU) Jena, Dornburgerstraße 24, Jena D-07743, Germany
| | - Michel Koenig
- Laboratoire de Génétique de Maladies Rares EA7402, Institut Universitaire de Recherche Clinique, Université de Montpellier, Montpellier F-34093, France
| | - Michael Ristow
- Institute of Nutrition, Friedrich Schiller University (FSU) Jena, Dornburgerstraße 24, Jena D-07743, Germany
| | - René Thierbach
- Institute of Nutrition, Friedrich Schiller University (FSU) Jena, Dornburgerstraße 24, Jena D-07743, Germany
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24
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Mollá B, Riveiro F, Bolinches-Amorós A, Muñoz-Lasso DC, Palau F, González-Cabo P. Two different pathogenic mechanisms, dying-back axonal neuropathy and pancreatic senescence, are present in the YG8R mouse model of Friedreich's ataxia. Dis Model Mech 2016; 9:647-57. [PMID: 27079523 PMCID: PMC4920149 DOI: 10.1242/dmm.024273] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Accepted: 04/03/2016] [Indexed: 12/16/2022] Open
Abstract
Frataxin (FXN) deficiency causes Friedreich’s ataxia (FRDA), a multisystem disorder with neurological and non-neurological symptoms. FRDA pathophysiology combines developmental and degenerative processes of dorsal root ganglia (DRG), sensory nerves, dorsal columns and other central nervous structures. A dying-back mechanism has been proposed to explain the peripheral neuropathy and neuropathology. In addition, affected individuals have non-neuronal symptoms such as diabetes mellitus or glucose intolerance. To go further in the understanding of the pathogenic mechanisms of neuropathy and diabetes associated with the disease, we have investigated the humanized mouse YG8R model of FRDA. By biochemical and histopathological studies, we observed abnormal changes involving muscle spindles, dorsal root axons and DRG neurons, but normal findings in the posterior columns and brain, which agree with the existence of a dying-back process similar to that described in individuals with FRDA. In YG8R mice, we observed a large number of degenerated axons surrounded by a sheath exhibiting enlarged adaxonal compartments or by a thin disrupted myelin sheath. Thus, both axonal damage and defects in Schwann cells might underlie the nerve pathology. In the pancreas, we found a high proportion of senescent islets of Langerhans in YG8R mice, which decreases the β-cell number and islet mass to pathological levels, being unable to maintain normoglycemia. As a whole, these results confirm that the lack of FXN induces different pathogenic mechanisms in the nervous system and pancreas in the mouse model of FRDA: dying back of the sensory nerves, and pancreatic senescence. Summary: Frataxin deficiency induces different pathogenic mechanisms in the nervous system and pancreas in a YG8R mouse model of Friedreich's ataxia (FRDA). Thus, the degenerative process in FRDA is determined by the cell type.
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Affiliation(s)
- Belén Mollá
- Program in Rare and Genetic Diseases and IBV/CSIC Associated Unit at CIPF, Centro de Investigación Príncipe Felipe (CIPF), Valencia 46012, Spain CIBER de Enfermedades Raras (CIBERER), Valencia 28029, Spain
| | - Fátima Riveiro
- Program in Rare and Genetic Diseases and IBV/CSIC Associated Unit at CIPF, Centro de Investigación Príncipe Felipe (CIPF), Valencia 46012, Spain CIBER de Enfermedades Raras (CIBERER), Valencia 28029, Spain
| | - Arantxa Bolinches-Amorós
- Program in Rare and Genetic Diseases and IBV/CSIC Associated Unit at CIPF, Centro de Investigación Príncipe Felipe (CIPF), Valencia 46012, Spain Cell Therapy Program, Centro de Investigación Príncipe Felipe (CIPF), Valencia 46012, Spain
| | - Diana C Muñoz-Lasso
- Program in Rare and Genetic Diseases and IBV/CSIC Associated Unit at CIPF, Centro de Investigación Príncipe Felipe (CIPF), Valencia 46012, Spain CIBER de Enfermedades Raras (CIBERER), Valencia 28029, Spain
| | - Francesc Palau
- Program in Rare and Genetic Diseases and IBV/CSIC Associated Unit at CIPF, Centro de Investigación Príncipe Felipe (CIPF), Valencia 46012, Spain CIBER de Enfermedades Raras (CIBERER), Valencia 28029, Spain Department of Genetic and Molecular Medicine, Institut de Recerca Pediàtrica Hospital San Joan de Déu, Barcelona 08950, Spain Department of Pediatrics, University of Barcelona School of Medicine, Barcelona 08036, Spain
| | - Pilar González-Cabo
- Program in Rare and Genetic Diseases and IBV/CSIC Associated Unit at CIPF, Centro de Investigación Príncipe Felipe (CIPF), Valencia 46012, Spain CIBER de Enfermedades Raras (CIBERER), Valencia 28029, Spain Department of Physiology, Faculty of Medicine and Dentistry, University of Valencia, Valencia 46010, Spain
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25
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Calap-Quintana P, Soriano S, Llorens JV, Al-Ramahi I, Botas J, Moltó MD, Martínez-Sebastián MJ. TORC1 Inhibition by Rapamycin Promotes Antioxidant Defences in a Drosophila Model of Friedreich's Ataxia. PLoS One 2015; 10:e0132376. [PMID: 26158631 PMCID: PMC4497667 DOI: 10.1371/journal.pone.0132376] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2015] [Accepted: 06/14/2015] [Indexed: 12/22/2022] Open
Abstract
Friedreich's ataxia (FRDA), the most common inherited ataxia in the Caucasian population, is a multisystemic disease caused by a significant decrease in the frataxin level. To identify genes capable of modifying the severity of the symptoms of frataxin depletion, we performed a candidate genetic screen in a Drosophila RNAi-based model of FRDA. We found that genetic reduction in TOR Complex 1 (TORC1) signalling improves the impaired motor performance phenotype of FRDA model flies. Pharmacologic inhibition of TORC1 signalling by rapamycin also restored this phenotype and increased the lifespan and ATP levels. Furthermore, rapamycin reduced the altered levels of malondialdehyde + 4-hydroxyalkenals and total glutathione of the model flies. The rapamycin-mediated protection against oxidative stress is due in part to an increase in the transcription of antioxidant genes mediated by cap-n-collar (Drosophila ortholog of Nrf2). Our results suggest that autophagy is indeed necessary for the protective effect of rapamycin in hyperoxia. Rapamycin increased the survival and aconitase activity of model flies subjected to high oxidative insult, and this improvement was abolished by the autophagy inhibitor 3-methyladenine. These results point to the TORC1 pathway as a new potential therapeutic target for FRDA and as a guide to finding new promising molecules for disease treatment.
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Affiliation(s)
| | - Sirena Soriano
- Department of Genetics, University of Valencia, Burjassot, Valencia, Spain
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | | | - Ismael Al-Ramahi
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Juan Botas
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - María Dolores Moltó
- Department of Genetics, University of Valencia, Burjassot, Valencia, Spain
- CIBERSAM, INCLIVA, Valencia, Spain
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Tai G, Corben LA, Gurrin L, Yiu EM, Churchyard A, Fahey M, Hoare B, Downie S, Delatycki MB. A study of up to 12 years of follow-up of Friedreich ataxia utilising four measurement tools. J Neurol Neurosurg Psychiatry 2015; 86:660-6. [PMID: 25112308 DOI: 10.1136/jnnp-2014-308022] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/05/2014] [Accepted: 07/16/2014] [Indexed: 11/03/2022]
Abstract
OBJECTIVE To explore the progression of Friedreich ataxia by analysing the change in scores of four clinical measures (the Friedreich Ataxia Rating Scale (FARS), the International Cooperative Ataxia Rating Scale (ICARS), the Functional Independence Measure (FIM) and the Modified Barthel Index (MBI)) over a period of up to 12 years, to ascertain the effects of clinical variables on performance of these measures, and to determine the most sensitive rating scale for measuring disease progression. METHODS We measured the disease progression of up to 147 individuals against disease duration grouped into 5-year intervals. Additional subgroups were created to study the effects of the size of the smaller FXN intron 1 GAA repeat size (GAA1) and onset age on rating scale performance. RESULTS Both the FARS and ICARS demonstrated greater change in the first 20 years post disease onset than in the subsequent 20 years during which there was little change in the mean score. While the FIM and MBI continued to deteriorate beyond 20 years post disease onset, floor effects were noted. As measured by the FARS, individuals with a larger GAA1 repeat were found to progress more quickly in the first 20 years of disease. CONCLUSIONS Individuals with larger GAA1 repeat sizes and earlier ages of disease onset were shown to deteriorate at a faster rate and were associated with greater FARS and ICARS scores and lower FIM and MBI scores, which are indicative of greater disease severity.
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Affiliation(s)
- Geneieve Tai
- Bruce Lefroy Centre for Genetic Health Research, Murdoch Childrens Research Institute, Parkville, Victoria, Australia
| | - Louise A Corben
- Bruce Lefroy Centre for Genetic Health Research, Murdoch Childrens Research Institute, Parkville, Victoria, Australia Monash Health, Clayton, Victoria, Australia
| | - Lyle Gurrin
- Department of Molecular, Environmental, Genetic and Analytic Epidemiology, University of Melbourne, Parkville, Victoria, Australia
| | - Eppie M Yiu
- Bruce Lefroy Centre for Genetic Health Research, Murdoch Childrens Research Institute, Parkville, Victoria, Australia Department of Paediatrics, University of Melbourne, Parkville, Victoria, Australia Children's Neuroscience Centre, Royal Children's Hospital, Parkville, Victoria, Australia
| | | | - Michael Fahey
- Department of Paediatrics, Monash University, Clayton, Victoria, Australia
| | | | | | - Martin B Delatycki
- Bruce Lefroy Centre for Genetic Health Research, Murdoch Childrens Research Institute, Parkville, Victoria, Australia Monash Health, Clayton, Victoria, Australia Department of Paediatrics, University of Melbourne, Parkville, Victoria, Australia Department of Paediatrics, Monash University, Clayton, Victoria, Australia Department of Clinical Genetics, Austin Health, Heidelberg, Victoria, Australia
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27
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Subramony S, Moscovich M, Ashizawa T. Genetics and Clinical Features of Inherited Ataxias. Mov Disord 2015. [DOI: 10.1016/b978-0-12-405195-9.00062-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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28
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Chutake YK, Lam C, Costello WN, Anderson M, Bidichandani SI. Epigenetic promoter silencing in Friedreich ataxia is dependent on repeat length. Ann Neurol 2014; 76:522-8. [PMID: 25112975 PMCID: PMC4191993 DOI: 10.1002/ana.24249] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Revised: 07/05/2014] [Accepted: 07/21/2014] [Indexed: 01/09/2023]
Abstract
OBJECTIVE Friedreich ataxia (FRDA) is caused by an expanded GAA triplet-repeat (GAA-TR) mutation in the FXN gene. Patients are typically homozygous for expanded alleles containing 100 to 1,300 triplets, and phenotypic severity is significantly correlated with the length of the shorter of the 2 expanded alleles. Patients have a severe deficiency of FXN transcript, which is predominantly caused by epigenetic silencing of the FXN promoter. We sought to determine whether the severity of FXN promoter silencing is related to the length of the expanded GAA-TR mutation in FRDA. METHODS Patient-derived lymphoblastoid cell lines bearing a range of expanded alleles (200-1,122 triplets) were evaluated for FXN transcript levels by quantitative reverse transcriptase polymerase chain reaction. FXN promoter function was directly measured by quantitative analysis of transcriptional initiation via metabolic labeling of newly synthesized transcripts in living cells. RESULTS FXN transcriptional deficiency was significantly correlated with the length of the shorter of the 2 expanded alleles, which was noted both upstream (R(2) = 0.84, p = 0.014) and downstream (R(2) = 0.89, p = 0.002) of the expanded GAA-TR mutation, suggesting that FXN promoter silencing in FRDA is related to repeat length. A bilinear regression model revealed that length dependence was strongest when the shorter of the 2 expanded alleles contained <400 triplets. Direct measurement of FXN promoter activity in patients with expanded alleles containing <400 versus >400 triplets in the shorter of the 2 expanded alleles revealed a significantly greater deficiency in individuals with longer GAA-TR alleles (p < 0.05). INTERPRETATION FXN promoter silencing in FRDA is dependent on the length of the expanded GAA-TR mutation.
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Affiliation(s)
- Yogesh K. Chutake
- Department of Pediatrics, University of Oklahoma College of Medicine, Oklahoma City, OK 73104
| | - Christina Lam
- Department of Pediatrics, University of Oklahoma College of Medicine, Oklahoma City, OK 73104
| | - Whitney N. Costello
- Department of Pediatrics, University of Oklahoma College of Medicine, Oklahoma City, OK 73104
| | - Michael Anderson
- Department of Biostatistics & Epidemiology, University of Oklahoma College of Public Health, Oklahoma City, OK 73104
| | - Sanjay I. Bidichandani
- Department of Pediatrics, University of Oklahoma College of Medicine, Oklahoma City, OK 73104
- Department of Biochemistry & Molecular Biology, University of Oklahoma College of Medicine, Oklahoma City, OK 73104
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29
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Ezzatizadeh V, Sandi C, Sandi M, Anjomani-Virmouni S, Al-Mahdawi S, Pook MA. MutLα heterodimers modify the molecular phenotype of Friedreich ataxia. PLoS One 2014; 9:e100523. [PMID: 24971578 PMCID: PMC4074104 DOI: 10.1371/journal.pone.0100523] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2014] [Accepted: 05/28/2014] [Indexed: 12/03/2022] Open
Abstract
BACKGROUND Friedreich ataxia (FRDA), the most common autosomal recessive ataxia disorder, is caused by a dynamic GAA repeat expansion mutation within intron 1 of FXN gene, resulting in down-regulation of frataxin expression. Studies of cell and mouse models have revealed a role for the mismatch repair (MMR) MutS-heterodimer complexes and the PMS2 component of the MutLα complex in the dynamics of intergenerational and somatic GAA repeat expansions: MSH2, MSH3 and MSH6 promote GAA repeat expansions, while PMS2 inhibits GAA repeat expansions. METHODOLOGY/PRINCIPAL FINDINGS To determine the potential role of the other component of the MutLα complex, MLH1, in GAA repeat instability in FRDA, we have analyzed intergenerational and somatic GAA repeat expansions from FXN transgenic mice that have been crossed with Mlh1 deficient mice. We find that loss of Mlh1 activity reduces both intergenerational and somatic GAA repeat expansions. However, we also find that loss of either Mlh1 or Pms2 reduces FXN transcription, suggesting different mechanisms of action for Mlh1 and Pms2 on GAA repeat expansion dynamics and regulation of FXN transcription. CONCLUSIONS/SIGNIFICANCE Both MutLα components, PMS2 and MLH1, have now been shown to modify the molecular phenotype of FRDA. We propose that upregulation of MLH1 or PMS2 could be potential FRDA therapeutic approaches to increase FXN transcription.
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Affiliation(s)
- Vahid Ezzatizadeh
- Division of Biosciences, School of Health Sciences and Social Care, Brunel University London, Uxbridge, United Kingdom
| | - Chiranjeevi Sandi
- Division of Biosciences, School of Health Sciences and Social Care, Brunel University London, Uxbridge, United Kingdom
| | - Madhavi Sandi
- Division of Biosciences, School of Health Sciences and Social Care, Brunel University London, Uxbridge, United Kingdom
| | - Sara Anjomani-Virmouni
- Division of Biosciences, School of Health Sciences and Social Care, Brunel University London, Uxbridge, United Kingdom
| | - Sahar Al-Mahdawi
- Division of Biosciences, School of Health Sciences and Social Care, Brunel University London, Uxbridge, United Kingdom
| | - Mark A. Pook
- Division of Biosciences, School of Health Sciences and Social Care, Brunel University London, Uxbridge, United Kingdom
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Puccio H, Anheim M, Tranchant C. Pathophysiogical and therapeutic progress in Friedreich ataxia. Rev Neurol (Paris) 2014; 170:355-65. [PMID: 24792433 DOI: 10.1016/j.neurol.2014.03.008] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Revised: 03/25/2014] [Accepted: 03/26/2014] [Indexed: 01/10/2023]
Abstract
Friedreich ataxia (FRDA) is the most common hereditary autosomal recessive ataxia, but is also a multisystemic condition with frequent presence of cardiomyopathy or diabetes. It has been linked to expansion of a GAA-triplet repeat in the first intron of the FXN gene, leading to a reduced level of frataxin, a mitochondrial protein which, by controlling both iron entry and/or sulfide production, is essential to properly assemble and protect the Fe-S cluster during the initial stage of biogenesis. Several data emphasize the role of oxidative damage in FRDA, but better understanding of pathophysiological consequences of FXN mutations has led to develop animal models. Conditional knockout models recapitulate important features of the human disease but lack the genetic context, GAA repeat expansion-based knock-in and transgenic models carry a GAA repeat expansion but they only show a very mild phenotype. Cells derived from FRDA patients constitute the most relevant frataxin-deficient cell model as they carry the complete frataxin locus together with GAA repeat expansions and regulatory sequences. Induced pluripotent stem cell (iPSC)-derived neurons present a maturation delay and lower mitochondrial membrane potential, while cardiomyocytes exhibit progressive mitochondrial degeneration, with frequent dark mitochondria and proliferation/accumulation of normal mitochondria. Efforts in developing therapeutic strategies can be divided into three categories: iron chelators, antioxidants and/or stimulants of mitochondrial biogenesis, and frataxin level modifiers. A promising therapeutic strategy that is currently the subject of intense research is to directly target the heterochromatin state of the GAA repeat expansion with histone deacytelase inhibitors (HDACi) to restore frataxin levels.
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Affiliation(s)
- H Puccio
- Translational medicine and neurogenetics, institut de génétique et de biologie moléculaire et cellulaire (IGBMC), 1, rue Laurent-Fries, BP 10142, 67404 Illkirch cedex, France; Inserm, U596, 1, rue Laurent-Fries, 67400 Illkirch Graffenstaden, France; CNRS, UMR7104, 1, rue Laurent-Fries, 67400 Illkirch Graffenstaden, France; Université de Strasbourg, 4, rue Blaise-Pascal, 67400 Strasbourg, France; Collège de France, chaire de génétique humaine, 1, rue Laurent-Fries, 67400 Illkirch Graffenstaden, France
| | - M Anheim
- Translational medicine and neurogenetics, institut de génétique et de biologie moléculaire et cellulaire (IGBMC), 1, rue Laurent-Fries, BP 10142, 67404 Illkirch cedex, France; Inserm, U596, 1, rue Laurent-Fries, 67400 Illkirch Graffenstaden, France; CNRS, UMR7104, 1, rue Laurent-Fries, 67400 Illkirch Graffenstaden, France; Université de Strasbourg, 4, rue Blaise-Pascal, 67400 Strasbourg, France; Service de neurologie, unité des pathologies du mouvement, hôpital de Hautepierre, hôpital universitaire, 1, place de l'Hôpital, 67000 Strasbourg, France
| | - C Tranchant
- Translational medicine and neurogenetics, institut de génétique et de biologie moléculaire et cellulaire (IGBMC), 1, rue Laurent-Fries, BP 10142, 67404 Illkirch cedex, France; Inserm, U596, 1, rue Laurent-Fries, 67400 Illkirch Graffenstaden, France; CNRS, UMR7104, 1, rue Laurent-Fries, 67400 Illkirch Graffenstaden, France; Université de Strasbourg, 4, rue Blaise-Pascal, 67400 Strasbourg, France; Service de neurologie, unité des pathologies du mouvement, hôpital de Hautepierre, hôpital universitaire, 1, place de l'Hôpital, 67000 Strasbourg, France.
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Lai Y, Beaver JM, Lorente K, Melo J, Ramjagsingh S, Agoulnik IU, Zhang Z, Liu Y. Base excision repair of chemotherapeutically-induced alkylated DNA damage predominantly causes contractions of expanded GAA repeats associated with Friedreich's ataxia. PLoS One 2014; 9:e93464. [PMID: 24691413 PMCID: PMC3972099 DOI: 10.1371/journal.pone.0093464] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2014] [Accepted: 03/06/2014] [Indexed: 11/18/2022] Open
Abstract
Expansion of GAA·TTC repeats within the first intron of the frataxin gene is the cause of Friedreich's ataxia (FRDA), an autosomal recessive neurodegenerative disorder. However, no effective treatment for the disease has been developed as yet. In this study, we explored a possibility of shortening expanded GAA repeats associated with FRDA through chemotherapeutically-induced DNA base lesions and subsequent base excision repair (BER). We provide the first evidence that alkylated DNA damage induced by temozolomide, a chemotherapeutic DNA damaging agent can induce massive GAA repeat contractions/deletions, but only limited expansions in FRDA patient lymphoblasts. We showed that temozolomide-induced GAA repeat instability was mediated by BER. Further characterization of BER of an abasic site in the context of (GAA)20 repeats indicates that the lesion mainly resulted in a large deletion of 8 repeats along with small expansions. This was because temozolomide-induced single-stranded breaks initially led to DNA slippage and the formation of a small GAA repeat loop in the upstream region of the damaged strand and a small TTC loop on the template strand. This allowed limited pol β DNA synthesis and the formation of a short 5'-GAA repeat flap that was cleaved by FEN1, thereby leading to small repeat expansions. At a later stage of BER, the small template loop expanded into a large template loop that resulted in the formation of a long 5'-GAA repeat flap. Pol β then performed limited DNA synthesis to bypass the loop, and FEN1 removed the long repeat flap ultimately causing a large repeat deletion. Our study indicates that chemotherapeutically-induced alkylated DNA damage can induce large contractions/deletions of expanded GAA repeats through BER in FRDA patient cells. This further suggests the potential of developing chemotherapeutic alkylating agents to shorten expanded GAA repeats for treatment of FRDA.
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Affiliation(s)
- Yanhao Lai
- Department of Environmental Health, Sichuan University West China School of Public Health, Chengdu, Sichuan, P. R. China
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida, United States of America
| | - Jill M. Beaver
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida, United States of America
| | - Karla Lorente
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida, United States of America
| | - Jonathan Melo
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida, United States of America
| | - Shyama Ramjagsingh
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida, United States of America
| | - Irina U. Agoulnik
- Department of Cellular Biology and Pharmacology, Florida International University, Miami, Florida, United States of America
| | - Zunzhen Zhang
- Department of Environmental Health, Sichuan University West China School of Public Health, Chengdu, Sichuan, P. R. China
- * E-mail: (ZZ); (YL)
| | - Yuan Liu
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida, United States of America
- * E-mail: (ZZ); (YL)
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HEIDARI MM, KHATAMI M, POURAKRAMI J. Novel Point Mutations in Frataxin Gene in Iranian Patients with Friedreich's Ataxia. IRANIAN JOURNAL OF CHILD NEUROLOGY 2014; 8:32-6. [PMID: 24665325 PMCID: PMC3943053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/21/2013] [Revised: 06/25/2013] [Accepted: 06/26/2013] [Indexed: 11/12/2022]
Abstract
OBJECTIVE Friedreich's ataxia is the most common form of hereditary ataxia with autosomal recessive pattern. More than 96% of patients are homozygous for GAA repeat extension on both alleles in the first intron of FXN gene and the remaining patients have been shown to be heterozygous for a GAA extension in one allele and point mutation in other allele. MATERIALS & METHODS In this study, exons of 1, 2, 3, and 5 of frataxin gene were searched by single strand conformation polymorphism polymerase chain reaction (PCR-SSCP) in 5 patients with GAA extension in one allele. For detection of exact mutation, samples with band shifts were sent for DNA sequencing. RESULTS Three novel point mutations were found in patients heterozygous for the GAA repeat expansion, p.S81A, p.Y123D, and p.S192C. CONCLUSION Our results showed that these point mutations in one allele with GAA extension in another allele are associated with FRDA signs. Thus, these results emphasize the importance of performing molecular genetic analysis for point mutations in FRDA patients.
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Affiliation(s)
| | - Mehri KHATAMI
- Department of Biology, Faculty of Sciences, Yazd University, Yazd, Iran
| | - Jafar POURAKRAMI
- Department of Biology, Faculty of Sciences, Science and Research Branch of the Islamic Azad University, Tehran, Iran
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Parkinson MH, Boesch S, Nachbauer W, Mariotti C, Giunti P. Clinical features of Friedreich's ataxia: classical and atypical phenotypes. J Neurochem 2013; 126 Suppl 1:103-17. [PMID: 23859346 DOI: 10.1111/jnc.12317] [Citation(s) in RCA: 153] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2013] [Revised: 05/15/2013] [Accepted: 05/15/2013] [Indexed: 11/27/2022]
Abstract
One hundred and fifty years since Nikolaus Friedreich's first description of the degenerative ataxic syndrome which bears his name, his description remains at the core of the classical clinical phenotype of gait and limb ataxia, poor balance and coordination, leg weakness, sensory loss, areflexia, impaired walking, dysarthria, dysphagia, eye movement abnormalities, scoliosis, foot deformities, cardiomyopathy and diabetes. Onset is typically around puberty with slow progression and shortened life-span often related to cardiac complications. Inheritance is autosomal recessive with the vast majority of cases showing an unstable intronic GAA expansion in both alleles of the frataxin gene on chromosome 9q13. A small number of cases are caused by a compound heterozygous expansion with a point mutation or deletion. Understanding of the underlying molecular biology has enabled identification of atypical phenotypes with late onset, or atypical features such as retained reflexes. Late-onset cases tend to have slower progression and are associated with smaller GAA expansions. Early-onset cases tend to have more rapid progression and a higher frequency of non-neurological features such as diabetes, cardiomyopathy, scoliosis and pes cavus. Compound heterozygotes, including those with large deletions, often have atypical features. In this paper, we review the classical and atypical clinical phenotypes of Friedreich's ataxia.
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Affiliation(s)
- Michael H Parkinson
- Department of Molecular Neuroscience, UCL Institute of Neurology, London, UK
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Perdomini M, Hick A, Puccio H, Pook MA. Animal and cellular models of Friedreich ataxia. J Neurochem 2013; 126 Suppl 1:65-79. [PMID: 23859342 DOI: 10.1111/jnc.12219] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2012] [Revised: 02/01/2013] [Accepted: 02/04/2013] [Indexed: 11/30/2022]
Abstract
The development and use of animal and cellular models of Friedreich ataxia (FRDA) are essential requirements for the understanding of FRDA disease mechanisms and the investigation of potential FRDA therapeutic strategies. Although animal and cellular models of lower organisms have provided valuable information on certain aspects of FRDA disease and therapy, it is intuitive that the most useful models are those of mammals and mammalian cells, which are the closest in physiological terms to FRDA patients. To date, there have been considerable efforts put into the development of several different FRDA mouse models and relevant FRDA mouse and human cell line systems. We summarize the principal mammalian FRDA models, discuss the pros and cons of each system, and describe the ways in which such models have been used to address two of the fundamental, as yet unanswered, questions regarding FRDA. Namely, what is the exact pathophysiology of FRDA and what is the detailed genetic and epigenetic basis of FRDA?
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Affiliation(s)
- Morgane Perdomini
- Translational Medecine and Neurogenetics, IGBMC-Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch, France
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Yandim C, Natisvili T, Festenstein R. Gene regulation and epigenetics in Friedreich's ataxia. J Neurochem 2013; 126 Suppl 1:21-42. [PMID: 23859339 DOI: 10.1111/jnc.12254] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2012] [Revised: 02/05/2013] [Accepted: 03/06/2013] [Indexed: 12/20/2022]
Abstract
This is an exciting time in the study of Friedreich's ataxia. Over the last 10 years much progress has been made in uncovering the mechanisms, whereby the Frataxin gene is silenced by (GAA)n repeat expansions and several of the findings are now ripe for testing in the clinic. The discovery that the Frataxin gene is heterochromatinised and that this can be antagonised in vivo has led to the tantalizing possibility that the disease might be amenable to a more radical therapeutic approach involving epigenetic modifiers. Here, we set out to review progress in the understanding of the fundamental mechanisms whereby genes are regulated at this level and how these findings have been applied to achieve a deeper understanding of the dysregulation that occurs as the primary genetic lesion in Friedreich's ataxia.
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Affiliation(s)
- Cihangir Yandim
- Gene Control Mechanisms and Disease, Department of Medicine and MRC Clinical Sciences Centre, Imperial College London, London, UK
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Analysis of the visual system in Friedreich ataxia. J Neurol 2013; 260:2362-9. [DOI: 10.1007/s00415-013-6978-z] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2013] [Revised: 05/20/2013] [Accepted: 05/25/2013] [Indexed: 10/26/2022]
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Soriano S, Llorens JV, Blanco-Sobero L, Gutiérrez L, Calap-Quintana P, Morales MP, Moltó MD, Martínez-Sebastián MJ. Deferiprone and idebenone rescue frataxin depletion phenotypes in a Drosophila model of Friedreich's ataxia. Gene 2013; 521:274-81. [PMID: 23542074 DOI: 10.1016/j.gene.2013.02.049] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2012] [Revised: 02/22/2013] [Accepted: 02/25/2013] [Indexed: 11/17/2022]
Abstract
Friedreich's ataxia (FRDA), the most common inherited ataxia, is a neurodegenerative disease caused by a reduction in the levels of the mitochondrial protein frataxin, the function of which remains a controversial matter. Several therapeutic approaches are being developed to increase frataxin expression and reduce the intramitochondrial iron aggregates and oxidative damage found in this disease. In this study, we tested separately the response of a Drosophila RNAi model of FRDA (Llorens et al., 2007) to treatment with the iron chelator deferiprone (DFP) and the antioxidant idebenone (IDE), which are both in clinical trials. The FRDA flies have a shortened life span and impaired motor coordination, and these phenotypes are more pronounced in oxidative stress conditions. In addition, under hyperoxia, the activity of the mitochondrial enzyme aconitase is strongly reduced in the FRDA flies. This study reports that DFP and IDE improve the life span and motor ability of frataxin-depleted flies. We show that DFP eliminates the excess of labile iron in the mitochondria and thus prevents the toxicity induced by iron accumulation. IDE treatment rescues aconitase activity in hyperoxic conditions. These results validate the use of our Drosophila model of FRDA to screen for therapeutic molecules to treat this disease.
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Affiliation(s)
- Sirena Soriano
- Departament de Genètica, Universitat de València, Burjassot, Valencia, Spain
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Li L, Voullaire L, Sandi C, Pook MA, Ioannou PA, Delatycki MB, Sarsero JP. Pharmacological screening using an FXN-EGFP cellular genomic reporter assay for the therapy of Friedreich ataxia. PLoS One 2013; 8:e55940. [PMID: 23418481 PMCID: PMC3572186 DOI: 10.1371/journal.pone.0055940] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2012] [Accepted: 01/03/2013] [Indexed: 11/18/2022] Open
Abstract
Friedreich ataxia (FRDA) is an autosomal recessive disorder characterized by neurodegeneration and cardiomyopathy. The presence of a GAA trinucleotide repeat expansion in the first intron of the FXN gene results in the inhibition of gene expression and an insufficiency of the mitochondrial protein frataxin. There is a correlation between expansion length, the amount of residual frataxin and the severity of disease. As the coding sequence is unaltered, pharmacological up-regulation of FXN expression may restore frataxin to therapeutic levels. To facilitate screening of compounds that modulate FXN expression in a physiologically relevant manner, we established a cellular genomic reporter assay consisting of a stable human cell line containing an FXN-EGFP fusion construct, in which the EGFP gene is fused in-frame with the entire normal human FXN gene present on a BAC clone. The cell line was used to establish a fluorometric cellular assay for use in high throughput screening (HTS) procedures. A small chemical library containing FDA-approved compounds and natural extracts was screened and analyzed. Compound hits identified by HTS were further evaluated by flow cytometry in the cellular genomic reporter assay. The effects on FXN mRNA and frataxin protein levels were measured in lymphoblast and fibroblast cell lines derived from individuals with FRDA and in a humanized GAA repeat expansion mouse model of FRDA. Compounds that were established to increase FXN gene expression and frataxin levels included several anti-cancer agents, the iron-chelator deferiprone and the phytoalexin resveratrol.
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Affiliation(s)
- Lingli Li
- Cell and Gene Therapy, Murdoch Childrens Research Institute, Parkville, Victoria, Australia
- Bruce Lefroy Centre for Genetic Health Research, Murdoch Childrens Research Institute, Parkville, Victoria, Australia
| | - Lucille Voullaire
- Cell and Gene Therapy, Murdoch Childrens Research Institute, Parkville, Victoria, Australia
| | - Chiranjeevi Sandi
- Division of Biosciences, School of Health Sciences and Social Care, Brunel University, Uxbridge, United Kingdom
| | - Mark A. Pook
- Division of Biosciences, School of Health Sciences and Social Care, Brunel University, Uxbridge, United Kingdom
| | - Panos A. Ioannou
- Cell and Gene Therapy, Murdoch Childrens Research Institute, Parkville, Victoria, Australia
- Department of Paediatrics, The University of Melbourne, Royal Children’s Hospital, Parkville, Victoria, Australia
| | - Martin B. Delatycki
- Bruce Lefroy Centre for Genetic Health Research, Murdoch Childrens Research Institute, Parkville, Victoria, Australia
- Department of Paediatrics, The University of Melbourne, Royal Children’s Hospital, Parkville, Victoria, Australia
- Department of Clinical Genetics, Austin Health, Heidelberg, Victoria, Australia
| | - Joseph P. Sarsero
- Cell and Gene Therapy, Murdoch Childrens Research Institute, Parkville, Victoria, Australia
- Bruce Lefroy Centre for Genetic Health Research, Murdoch Childrens Research Institute, Parkville, Victoria, Australia
- Department of Paediatrics, The University of Melbourne, Royal Children’s Hospital, Parkville, Victoria, Australia
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Berciano J, García A, Infante J. Peripheral nerve involvement in hereditary cerebellar and multisystem degenerative disorders. HANDBOOK OF CLINICAL NEUROLOGY 2013; 115:907-32. [PMID: 23931821 DOI: 10.1016/b978-0-444-52902-2.00051-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Hereditary ataxias (HA) encompass an increasing number of degenerative disorders characterized by progressive cerebellar ataxia usually accompanied by extracerebellar semeiology including peripheral nerve involvement. Classically, HA were classified according to their pathological hallmark comprising three main forms: (1) spinal form predominantly with degeneration of spinocerebellar tracts, posterior columns, and pyramidal tracts (Friedreich's ataxia, FA); (2) olivopontocerebellar atrophy (OPCA); and (3) cortical cerebellar atrophy (CCA). In the 1980s Harding proposed a clinico-genetic classification based upon age of onset, modality of transmission, and clinical semeiology. The main categories in this classification were as follows: (1) early onset cerebellar ataxia (EOCA) with age of onset below 25 years and usually with autosomal recessive (AR) transmission (this group encompasses FA and syndromes different from FA); (2) autosomal dominant cerebellar ataxia (ADCA) with adult onset and with either cerebellar-plus syndrome or pure cerebellar semeiology; and (3) idiopathic late onset onset cerebellar ataxia (ILOCA). With the advent of molecular genetics, the nosology of HA has been in a state of constant flux. At present EOCA comprises at least 17 genotypes (designated with the acronym of ARCA derived from AR cerebellar ataxia), whereas under the umbrella of ADCA 30 genotypes have been reported. In this chapter we will review peripheral nerve involvement in classical pathological entities (OPCA and CCA), ARCA, ADCA, and ILOCA paying special attention to the most prevalent syndromes in each category. As a general rule, nerve involvement is relatively common in any form of ataxia except ILOCA, the most common pattern being either sensory or sensorimotor neuronopathy with a dying-back process. An exception to this rule is AR spastic ataxia of Charlevoix-Saguenay where nerve conduction studies show the characteristic pattern of intermediate neuropathy implying that sacsin mutation causes both axonal and Schwann cell dysfunction.
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Affiliation(s)
- José Berciano
- Department of Neurology and Clinical Neurophysiology, University Hospital "Marqués de Valdecilla (IFIMAV)", University of Cantabria and Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas, Santander, Spain.
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Hick A, Wattenhofer-Donzé M, Chintawar S, Tropel P, Simard JP, Vaucamps N, Gall D, Lambot L, André C, Reutenauer L, Rai M, Teletin M, Messaddeq N, Schiffmann SN, Viville S, Pearson CE, Pandolfo M, Puccio H. Neurons and cardiomyocytes derived from induced pluripotent stem cells as a model for mitochondrial defects in Friedreich's ataxia. Dis Model Mech 2012; 6:608-21. [PMID: 23136396 PMCID: PMC3634645 DOI: 10.1242/dmm.010900] [Citation(s) in RCA: 111] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Friedreich's ataxia (FRDA) is a recessive neurodegenerative disorder commonly associated with hypertrophic cardiomyopathy. FRDA is due to expanded GAA repeats within the first intron of the gene encoding frataxin, a conserved mitochondrial protein involved in iron-sulphur cluster biosynthesis. This mutation leads to partial gene silencing and substantial reduction of the frataxin level. To overcome limitations of current cellular models of FRDA, we derived induced pluripotent stem cells (iPSCs) from two FRDA patients and successfully differentiated them into neurons and cardiomyocytes, two affected cell types in FRDA. All FRDA iPSC lines displayed expanded GAA alleles prone to high instability and decreased levels of frataxin, but no biochemical phenotype was observed. Interestingly, both FRDA iPSC-derived neurons and cardiomyocytes exhibited signs of impaired mitochondrial function, with decreased mitochondrial membrane potential and progressive mitochondrial degeneration, respectively. Our data show for the first time that FRDA iPSCs and their neuronal and cardiac derivatives represent promising models for the study of mitochondrial damage and GAA expansion instability in FRDA.
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Affiliation(s)
- Aurore Hick
- Translational Medicine and Neurogenetics, Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), 67404 Illkirch, France
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Kisfali P, Melegh B. [Molecular genetic diagnosis of Friedreich's ataxia. Ten years experience based on blood sample analysis]. Orv Hetil 2012; 153:852-5. [PMID: 22641259 DOI: 10.1556/oh.2012.29372] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
UNLABELLED Mutations of the frataxin gene give the most common underlying genetic background of recessively inheritable type ataxias in Europe. In our department, we have been establishing the molecular genetic diagnosis of Friedreich's ataxia since 2001. We analyzed a total of 221 blood samples from the whole country. METHODS After fragment analysis we performed direct exon sequencing. RESULTS This study summarizes the retrospective analysis of these genetic test results. Pathological alteration was identified in altogether 26 cases. 2 expanded alleles were found in intron 1 in all 26 genetically confirmed patients; which is not more than 12% of the total analyzed samples. We did exon sequencing in the case of patients having one expanded allele and found no point mutation in any of the cases. CONCLUSIONS In our setting, we could not verify the diagnosis by genetic analysis in a remarkable number of patients, which on one hand underlines the importance of clinical neurologic and clinical genetic analyses before performing tests, and on the other hand, it raises the need to examine the patients for other ataxia types.
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Affiliation(s)
- Péter Kisfali
- Pécsi Tudományegyetem, Klinikai Központ, Általános Orvostudományi Kar Orvosi Genetikai Intézet Pécs Szigeti út 12.
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The mismatch repair system protects against intergenerational GAA repeat instability in a Friedreich ataxia mouse model. Neurobiol Dis 2012; 46:165-71. [PMID: 22289650 DOI: 10.1016/j.nbd.2012.01.002] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2011] [Revised: 12/21/2011] [Accepted: 01/09/2012] [Indexed: 11/21/2022] Open
Abstract
Friedreich ataxia (FRDA) is an autosomal recessive neurodegenerative disorder caused by a dynamic GAA repeat expansion mutation within intron 1 of the FXN gene. Studies of mouse models for other trinucleotide repeat (TNR) disorders have revealed an important role of mismatch repair (MMR) proteins in TNR instability. To explore the potential role of MMR proteins on intergenerational GAA repeat instability in FRDA, we have analyzed the transmission of unstable GAA repeat expansions from FXN transgenic mice which have been crossed with mice that are deficient for Msh2, Msh3, Msh6 or Pms2. We find in all cases that absence of parental MMR protein not only maintains transmission of GAA expansions and contractions, but also increases GAA repeat mutability (expansions and/or contractions) in the offspring. This indicates that Msh2, Msh3, Msh6 and Pms2 proteins are not the cause of intergenerational GAA expansions or contractions, but act in their canonical MMR capacity to protect against GAA repeat instability. We further identified differential modes of action for the four MMR proteins. Thus, Msh2 and Msh3 protect against GAA repeat contractions, while Msh6 protects against both GAA repeat expansions and contractions, and Pms2 protects against GAA repeat expansions and also promotes contractions. Furthermore, we detected enhanced occupancy of Msh2 and Msh3 proteins downstream of the FXN expanded GAA repeat, suggesting a model in which Msh2/3 dimers are recruited to this region to repair mismatches that would otherwise produce intergenerational GAA contractions. These findings reveal substantial differences in the intergenerational dynamics of expanded GAA repeat sequences compared with expanded CAG/CTG repeats, where Msh2 and Msh3 are thought to actively promote repeat expansions.
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Affiliation(s)
- Massimo Pandolfo
- Brussels Free University and Erasme Hospital, Brussels, Belgium.
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Kelly M, Bagnall RD, Peverill RE, Donelan L, Corben L, Delatycki MB, Semsarian C. A polymorphic miR-155 binding site in AGTR1 is associated with cardiac hypertrophy in Friedreich ataxia. J Mol Cell Cardiol 2011; 51:848-54. [PMID: 21771600 DOI: 10.1016/j.yjmcc.2011.07.001] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/24/2011] [Revised: 06/22/2011] [Accepted: 07/05/2011] [Indexed: 11/26/2022]
Abstract
Friedreich ataxia (FRDA) is an autosomal recessive neurodegenerative condition with a heterogeneous cardiac phenotype caused primarily by an expanded GAA trinucleotide repeat in the frataxin gene (FXN). FXN is important in mitochondrial iron efflux, sensitivity to oxidative stress, and cell death. The number of GAA repeats on the smaller FXN allele (GAA1) only accounts for a portion of the observed variability in cardiac phenotype. Genetic modifying factors, such as single nucleotide polymorphisms (SNPs) in genes of the Renin-Angiotensin-Aldosterone system (RAAS), may contribute to phenotype variability. This study investigated genetic variability in the angiotensin-II type-1 receptor (AGTR1), angiotensin-converting enzyme (ACE), and ACE2 genes as cardiac phenotype modifying factors in FRDA patients. Comprehensive review of the AGTR1, ACE and ACE2 genes identified twelve haplotype tagging SNPs. Correlation of these SNPs with left ventricular internal diameter in diastole (LVIDd), interventricular septal wall thickness (SWT) and left ventricular mass (LVM) was examined in a large Australian FRDA cohort (n=79) with adjustments performed for GAA repeats, age, sex, body surface area and diastolic blood pressure. A significant inverse relationship was observed between GAA1 and LVIDd (p=0.010) but not with SWT or LVM after adjustment for covariates. The AGTR1 polymorphism rs5186 was more common in FRDA patients than in a control population (p=0.002). Using a recessive model of inheritance, the C allele of rs5186 was associated with a significant increase in SWT (p=0.003) and LVM (p=0.001). This functional polymorphism increases expression of AGTR1 by altering the binding site for miR-155, a regulatory microRNA. No significant associations with left ventricular structure were observed for the remaining RAAS polymorphisms. The AGTR1 polymorphism rs5186 appears to modify the FRDA cardiac phenotype independently of GAA1. This study supports the role of RAAS polymorphisms as modifiers of cardiac phenotype in FRDA patients.
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Affiliation(s)
- Matthew Kelly
- Agnes Ginges Centre for Molecular Cardiology, Centenary Institute, Sydney, New South Wales, Australia
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Kemp K, Mallam E, Hares K, Witherick J, Scolding N, Wilkins A. Mesenchymal stem cells restore frataxin expression and increase hydrogen peroxide scavenging enzymes in Friedreich ataxia fibroblasts. PLoS One 2011; 6:e26098. [PMID: 22016819 PMCID: PMC3189234 DOI: 10.1371/journal.pone.0026098] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2011] [Accepted: 09/19/2011] [Indexed: 01/01/2023] Open
Abstract
Dramatic advances in recent decades in understanding the genetics of Friedreich ataxia (FRDA)--a GAA triplet expansion causing greatly reduced expression of the mitochondrial protein frataxin--have thus far yielded no therapeutic dividend, since there remain no effective treatments that prevent or even slow the inevitable progressive disability in affected individuals. Clinical interventions that restore frataxin expression are attractive therapeutic approaches, as, in theory, it may be possible to re-establish normal function in frataxin deficient cells if frataxin levels are increased above a specific threshold. With this in mind several drugs and cytokines have been tested for their ability to increase frataxin levels. Cell transplantation strategies may provide an alternative approach to this therapeutic aim, and may also offer more widespread cellular protective roles in FRDA. Here we show a direct link between frataxin expression in fibroblasts derived from FRDA patients with both decreased expression of hydrogen peroxide scavenging enzymes and increased sensitivity to hydrogen peroxide-mediated toxicity. We demonstrate that normal human mesenchymal stem cells (MSCs) induce both an increase in frataxin gene and protein expression in FRDA fibroblasts via secretion of soluble factors. Finally, we show that exposure to factors produced by human MSCs increases resistance to hydrogen peroxide-mediated toxicity in FRDA fibroblasts through, at least in part, restoring the expression of the hydrogen peroxide scavenging enzymes catalase and glutathione peroxidase 1. These findings suggest, for the first time, that stem cells may increase frataxin levels in FRDA and transplantation of MSCs may offer an effective treatment for these patients.
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Affiliation(s)
- Kevin Kemp
- Multiple Sclerosis and Stem Cell Group, Institute of Clinical Neurosciences, School of Clinical Sciences, University of Bristol, Bristol, United Kingdom.
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García-Giménez JL, Gimeno A, Gonzalez-Cabo P, Dasí F, Bolinches-Amorós A, Mollá B, Palau F, Pallardó FV. Differential expression of PGC-1α and metabolic sensors suggest age-dependent induction of mitochondrial biogenesis in Friedreich ataxia fibroblasts. PLoS One 2011; 6:e20666. [PMID: 21687738 PMCID: PMC3110204 DOI: 10.1371/journal.pone.0020666] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2010] [Accepted: 05/10/2011] [Indexed: 02/03/2023] Open
Abstract
Background Friedreich's ataxia (FRDA) is a mitochondrial rare disease, which molecular origin is associated with defect in the expression of frataxin. The pathological consequences are degeneration of nervous system structures and cardiomyopathy with necrosis and fibrosis, among others. Principal Findings Using FRDA fibroblasts we have characterized the oxidative stress status and mitochondrial biogenesis. We observed deficiency of MnSOD, increased ROS levels and low levels of ATP. Expression of PGC-1α and mtTFA was increased and the active form of the upstream signals p38 MAPK and AMPK in fibroblasts from two patients. Interestingly, the expression of energetic factors correlated with the natural history of disease of the patients, the age when skin biopsy was performed and the size of the GAA expanded alleles. Furthermore, idebenone inhibit mitochondriogenic responses in FRDA cells. Conclusions The induction of mitochondrial biogenesis in FRDA may be a consequence of the mitochondrial impairment associated with disease evolution. The increase of ROS and the involvement of the oxidative phosphorylation may be an early event in the cell pathophysiology of frataxin deficiency, whereas increase of mitochondriogenic response might be a later phenomenon associated to the individual age and natural history of the disease, being more evident as the patient age increases and disease evolves. This is a possible explanation of heart disease in FRDA.
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Affiliation(s)
- José Luis García-Giménez
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Valencia, Spain
- Fundación del Hospital Clínico Universitat de Valencia, FIHCUV-Incliva, Valencia, Spain
| | - Amparo Gimeno
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Valencia, Spain
- Fundación del Hospital Clínico Universitat de Valencia, FIHCUV-Incliva, Valencia, Spain
| | - Pilar Gonzalez-Cabo
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Valencia, Spain
- Instituto de Biomedicina Valencia, Valencia, Spain
| | - Francisco Dasí
- Fundación del Hospital Clínico Universitat de Valencia, FIHCUV-Incliva, Valencia, Spain
| | - Arantxa Bolinches-Amorós
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Valencia, Spain
- Instituto de Biomedicina Valencia, Valencia, Spain
| | - Belén Mollá
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Valencia, Spain
- Instituto de Biomedicina Valencia, Valencia, Spain
| | - Francesc Palau
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Valencia, Spain
- Instituto de Biomedicina Valencia, Valencia, Spain
| | - Federico V. Pallardó
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Valencia, Spain
- Fundación del Hospital Clínico Universitat de Valencia, FIHCUV-Incliva, Valencia, Spain
- Department of Physiology, Medical School, Universitat de València, Valencia, Spain
- * E-mail:
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Holloway TP, Rowley SM, Delatycki MB, Sarsero JP. Detection of interruptions in the GAA trinucleotide repeat expansion in the FXN gene of Friedreich ataxia. Biotechniques 2011; 50:182-6. [PMID: 21486239 DOI: 10.2144/000113615] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2010] [Accepted: 01/06/2011] [Indexed: 11/23/2022] Open
Abstract
Friedreich ataxia is a neurodegenerative disorder caused by the expansion of a GAA trinucleotide repeat sequence within the first intron of the FXN gene. Interruptions in the GAA repeat may serve to alleviate the inhibitory effects of the GAA expansion on FXN gene expression and to decrease pathogenicity. We have developed a simple and rapid PCR- and restriction enzyme-based assay to assess the purity of GAA repeat sequences.
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Affiliation(s)
- Timothy P Holloway
- Bruce Lefroy Centre for Genetic Health Research, Murdoch Childrens Research Institute, Royal Children's Hospital, Parkville, Victoria, Australia
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Pregnancy with Friedreich ataxia: a retrospective review of medical risks and psychosocial implications. Am J Obstet Gynecol 2010; 203:224.e1-5. [PMID: 20478553 DOI: 10.1016/j.ajog.2010.03.046] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2009] [Revised: 02/25/2010] [Accepted: 03/22/2010] [Indexed: 10/19/2022]
Abstract
OBJECTIVE Friedreich ataxia (FRDA) is an autosomal recessive, neurodegenerative disease. Recent medical advances have improved the average life expectancy, and as such, many female patients are contemplating pregnancy. However, little research exists exploring the medical or psychosocial complications that arise from pregnancy with this disease. STUDY DESIGN In this study, we retrospectively examined 31 women with FRDA who had 65 pregnancies, resulting in 56 live offspring. RESULTS FRDA did not appear to increase the risk of spontaneous abortion, preeclampsia, or preterm birth. Despite the sensory and proprioceptive loss that occurs in FRDA, nearly four fifths of births were vaginal. Of babies, 94.4% were discharged home with their mothers. Equal numbers of women reported that pregnancy made their disease symptoms worse, better, or unchanged. CONCLUSION This study demonstrates that women with FRDA can have uncomplicated pregnancies that do not uniformly complicate disease symptomatology.
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Santos R, Lefevre S, Sliwa D, Seguin A, Camadro JM, Lesuisse E. Friedreich ataxia: molecular mechanisms, redox considerations, and therapeutic opportunities. Antioxid Redox Signal 2010; 13:651-90. [PMID: 20156111 PMCID: PMC2924788 DOI: 10.1089/ars.2009.3015] [Citation(s) in RCA: 134] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/20/2009] [Revised: 02/08/2010] [Accepted: 02/14/2010] [Indexed: 12/14/2022]
Abstract
Mitochondrial dysfunction and oxidative damage are at the origin of numerous neurodegenerative diseases like Friedreich ataxia and Alzheimer and Parkinson diseases. Friedreich ataxia (FRDA) is the most common hereditary ataxia, with one individual affected in 50,000. This disease is characterized by progressive degeneration of the central and peripheral nervous systems, cardiomyopathy, and increased incidence of diabetes mellitus. FRDA is caused by a dynamic mutation, a GAA trinucleotide repeat expansion, in the first intron of the FXN gene. Fewer than 5% of the patients are heterozygous and carry point mutations in the other allele. The molecular consequences of the GAA triplet expansion is transcription silencing and reduced expression of the encoded mitochondrial protein, frataxin. The precise cellular role of frataxin is not known; however, it is clear now that several mitochondrial functions are not performed correctly in patient cells. The affected functions include respiration, iron-sulfur cluster assembly, iron homeostasis, and maintenance of the redox status. This review highlights the molecular mechanisms that underlie the disease phenotypes and the different hypothesis about the function of frataxin. In addition, we present an overview of the most recent therapeutic approaches for this severe disease that actually has no efficient treatment.
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Affiliation(s)
- Renata Santos
- Mitochondria, Metals and Oxidative Stress Laboratory, Institut Jacques Monod (UMR 7592 CNRS–University Paris-Diderot), Paris, France
| | - Sophie Lefevre
- Mitochondria, Metals and Oxidative Stress Laboratory, Institut Jacques Monod (UMR 7592 CNRS–University Paris-Diderot), Paris, France
- University Pierre et Marie Curie, Paris, France
| | - Dominika Sliwa
- Mitochondria, Metals and Oxidative Stress Laboratory, Institut Jacques Monod (UMR 7592 CNRS–University Paris-Diderot), Paris, France
| | - Alexandra Seguin
- Mitochondria, Metals and Oxidative Stress Laboratory, Institut Jacques Monod (UMR 7592 CNRS–University Paris-Diderot), Paris, France
| | - Jean-Michel Camadro
- Mitochondria, Metals and Oxidative Stress Laboratory, Institut Jacques Monod (UMR 7592 CNRS–University Paris-Diderot), Paris, France
| | - Emmanuel Lesuisse
- Mitochondria, Metals and Oxidative Stress Laboratory, Institut Jacques Monod (UMR 7592 CNRS–University Paris-Diderot), Paris, France
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Mariño TC, Zaldivar YG, Mesa JML, Mederos LA, Rodríguez RA, Gotay DA, Labrada RR, Ochoa NC, Macleod P, Pérez LV. Low predisposition to instability of the Friedreich ataxia gene in Cuban population. Clin Genet 2010; 77:598-600. [PMID: 20569261 DOI: 10.1111/j.1399-0004.2009.01361.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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