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Alemany-Perna B, Tamarit J, Cabiscol E, Delaspre F, Miguela A, Huertas-Pons JM, Quiroga-Varela A, Merchan Ruiz M, López Domínguez D, Ramió I Torrentà L, Genís D, Ros J. Calcitriol Treatment Is Safe and Increases Frataxin Levels in Friedreich Ataxia Patients. Mov Disord 2024; 39:1099-1108. [PMID: 38696306 DOI: 10.1002/mds.29808] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2023] [Revised: 03/22/2024] [Accepted: 03/25/2024] [Indexed: 05/04/2024] Open
Abstract
BACKGROUND Calcitriol, the active form of vitamin D (also known as 1,25-dihydroxycholecalciferol), improves the phenotype and increases frataxin levels in cell models of Friedreich ataxia (FRDA). OBJECTIVES Based on these results, we aimed measuring the effects of a calcitriol dose of 0.25 mcg/24h in the neurological function and frataxin levels when administered to FRDA patients for a year. METHODS 20 FRDA patients where recluted and 15 patients completed the treatment for a year. Evaluations of neurological function changes (SARA scale, 9-HPT, 8-MWT, PATA test) and quality of life (Barthel Scale and Short Form (36) Health Survey [SF-36] quality of life questionnaire) were performed. Frataxin amounts were measured in isolated platelets obtained from these FRDA patients, from heterozygous FRDA carriers (relatives of the FA patients) and from non-heterozygous sex and age matched controls. RESULTS Although the patients did not experience any observable neurological improvement, there was a statistically significant increase in frataxin levels from initial values, 5.5 to 7.0 pg/μg after 12 months. Differences in frataxin levels referred to total protein levels were observed among sex- and age-matched controls (18.1 pg/μg), relative controls (10.1 pg/μg), and FRDA patients (5.7 pg/μg). The treatment was well tolerated by most patients, and only some of them experienced minor adverse effects at the beginning of the trial. CONCLUSIONS Calcitriol dosage used (0.25 mcg/24 h) is safe for FRDA patients, and it increases frataxin levels. We cannot rule out that higher doses administered longer could yield neurological benefits. © 2024 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.
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Affiliation(s)
- Berta Alemany-Perna
- Ataxia Unit, Neurology Service, ICS/IAS, Hospital Josep Trueta/Hospital Santa Caterina, Girona/Salt, Spain
- Department of Medical Sciences, University of Girona (UdG), Girona, Spain
- Neurodegeneration and Neuroinflammacion Group, Institut d'Investigació Biomèdica de Girona (IDIBGI), Girona, Spain
| | - Jordi Tamarit
- Departament de Ciències Mèdiques Bàsiques, Institut de Recerca Biomèdica de Lleida (IRBLleida), Universitat de Lleida, Lleida, Spain
| | - Elisa Cabiscol
- Departament de Ciències Mèdiques Bàsiques, Institut de Recerca Biomèdica de Lleida (IRBLleida), Universitat de Lleida, Lleida, Spain
| | - Fabien Delaspre
- Departament de Ciències Mèdiques Bàsiques, Institut de Recerca Biomèdica de Lleida (IRBLleida), Universitat de Lleida, Lleida, Spain
| | - Albert Miguela
- Neurodegeneration and Neuroinflammacion Group, Institut d'Investigació Biomèdica de Girona (IDIBGI), Girona, Spain
| | - Joana Maria Huertas-Pons
- Neurodegeneration and Neuroinflammacion Group, Institut d'Investigació Biomèdica de Girona (IDIBGI), Girona, Spain
| | - Ana Quiroga-Varela
- Neurodegeneration and Neuroinflammacion Group, Institut d'Investigació Biomèdica de Girona (IDIBGI), Girona, Spain
| | - Miguel Merchan Ruiz
- Neurodegeneration and Neuroinflammacion Group, Institut d'Investigació Biomèdica de Girona (IDIBGI), Girona, Spain
| | - Daniel López Domínguez
- Ataxia Unit, Neurology Service, ICS/IAS, Hospital Josep Trueta/Hospital Santa Caterina, Girona/Salt, Spain
- Department of Medical Sciences, University of Girona (UdG), Girona, Spain
- Neurodegeneration and Neuroinflammacion Group, Institut d'Investigació Biomèdica de Girona (IDIBGI), Girona, Spain
| | - Lluís Ramió I Torrentà
- Department of Medical Sciences, University of Girona (UdG), Girona, Spain
- Neurology Service, ICS/IAS, Hospital Josep Trueta/Hospital Santa Caterina, Girona/Salt, Neurodegeneration and Neuroinflammacion Group (IDIBGI), Girona/Salt, Spain
| | - David Genís
- Neurodegeneration and Neuroinflammacion Group, Institut d'Investigació Biomèdica de Girona (IDIBGI), Girona, Spain
| | - Joaquim Ros
- Departament de Ciències Mèdiques Bàsiques, Institut de Recerca Biomèdica de Lleida (IRBLleida), Universitat de Lleida, Lleida, Spain
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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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Brown AF, Parkinson MH, Garcia-Moreno H, Mudanohwo E, Labrum R, Sweeney M, Giunti P. Friedreich's Ataxia Frequency in a Large Cohort of Genetically Undetermined Ataxia Patients. Front Neurol 2021; 12:736253. [PMID: 34956042 PMCID: PMC8697107 DOI: 10.3389/fneur.2021.736253] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2021] [Accepted: 10/19/2021] [Indexed: 11/25/2022] Open
Abstract
Background: Patients with suspected genetic ataxia are often tested for Friedreich's ataxia (FRDA) and/or a variety of spinocerebellar ataxias (SCAs). FRDA can present with atypical, late-onset forms and so may be missed in the diagnostic process. We aimed to determine FRDA-positive subjects among two cohorts of patients referred to a specialist ataxia centre either for FRDA or SCA testing to determine the proportion of FRDA cases missed in the diagnostic screening process. Methods: 2000 SCA-negative ataxia patients, not previously referred for FRDA testing (group A), were tested for FRDA expansions and mutations. This group was compared with 1768 ataxia patients who had been previously referred for FRDA testing (group B) and were therefore more likely to have a typical presentation. The phenotypes of positive cases were assessed through review of the clinical case notes. Results: Three patients (0.2%) in group A had the FRDA expansion on both alleles, compared with 207 patients (11.7%) in group B. The heterozygous carrier rate across both cohorts was of 41 out of 3,768 cases (1.1%). The size of the expansions in the three FRDA-positive cases in group A was small, and their presentation atypical with late-onset. Conclusions: This study demonstrates that FRDA is very rare among patients who were referred purely for SCA testing without the clinical suspicion of FRDA. Such cases should be referred to specialist ataxia centres for more extensive testing to improve patient management and outcomes.
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Affiliation(s)
- Alexander F. Brown
- Ataxia Centre, Department of Clinical and Movement Neurosciences, UCL Queen Square Institute of Neurology, Queen Square, London, United Kingdom
| | - Michael H. Parkinson
- Ataxia Centre, Department of Clinical and Movement Neurosciences, UCL Queen Square Institute of Neurology, Queen Square, London, United Kingdom
| | - Hector Garcia-Moreno
- Ataxia Centre, Department of Clinical and Movement Neurosciences, UCL Queen Square Institute of Neurology, Queen Square, London, United Kingdom
| | - Ese Mudanohwo
- Neurogenetics Unit, National Hospital for Neurology & Neurosurgery, University College London Hospitals, Queen Square, London, United Kingdom
| | - Robyn Labrum
- Neurogenetics Unit, National Hospital for Neurology & Neurosurgery, University College London Hospitals, Queen Square, London, United Kingdom
| | - Mary Sweeney
- Neurogenetics Unit, National Hospital for Neurology & Neurosurgery, University College London Hospitals, Queen Square, London, United Kingdom
| | - Paola Giunti
- Ataxia Centre, Department of Clinical and Movement Neurosciences, UCL Queen Square Institute of Neurology, Queen Square, London, United Kingdom
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Jimenez-Tellez N, Greenway SC. Cellular models for human cardiomyopathy: What is the best option? World J Cardiol 2019; 11:221-235. [PMID: 31754410 PMCID: PMC6859298 DOI: 10.4330/wjc.v11.i10.221] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/09/2019] [Revised: 06/17/2019] [Accepted: 09/25/2019] [Indexed: 02/06/2023] Open
Abstract
The genetic cardiomyopathies are a group of disorders related by abnormal myocardial structure and function. Although individually rare, these diseases collectively represent a significant health burden since they usually develop early in life and are a major cause of morbidity and mortality amongst affected children. The heterogeneity and rarity of these disorders requires the use of an appropriate model system in order to characterize the mechanism of disease and develop useful therapeutics since standard drug trials are infeasible. A common approach to study human disease involves the use of animal models, especially rodents, but due to important biological and physiological differences, this model system may not recapitulate human disease. An alternative approach for studying the metabolic cardiomyopathies relies on the use of cellular models which have most frequently been immortalized cell lines or patient-derived fibroblasts. However, the recent introduction of induced pluripotent stem cells (iPSCs), which have the ability to differentiate into any cell type in the body, is of great interest and has the potential to revolutionize the study of rare diseases. In this paper we review the advantages and disadvantages of each model system by comparing their utility for the study of mitochondrial cardiomyopathy with a particular focus on the use of iPSCs in cardiovascular biology for the modeling of rare genetic or metabolic diseases.
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Affiliation(s)
- Nerea Jimenez-Tellez
- Department of Biochemistry & Molecular Biology, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 4N1, Canada
| | - Steven C Greenway
- Departments of Pediatrics, Cardiac Sciences, Biochemistry & Molecular Biology, Cumming School of Medicine, Libin Cardiovascular Institute of Alberta, Alberta Children’s Hospital Research Institute, University of Calgary, Calgary, AB T2N 4N1, Canada
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Simon AL, Meyblum J, Roche B, Vidal C, Mazda K, Husson I, Ilharreborde B. Scoliosis in Patients With Friedreich Ataxia: Results of a Consecutive Prospective Series. Spine Deform 2019; 7:812-821. [PMID: 31495483 DOI: 10.1016/j.jspd.2019.02.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/23/2018] [Revised: 02/08/2019] [Accepted: 02/09/2019] [Indexed: 11/19/2022]
Abstract
STUDY DESIGN Prospective monocentric study. OBJECTIVES To describe the radiologic characteristics and evolution of spinal shapes in a pediatric cohort of patients with Friedreich ataxia (FA). SUMMARY OF BACKGROUND DATA FA is a spinocerebellar degenerative disorder responsible for gait impairment in children and young adults, and several orthopedic deformities can occur during growth, including scoliosis. However, curves' characteristics and their natural evolution have been poorly described, and the subsequent therapeutic management remains controversial. METHODS Sixty six FA patients were prospectively included between 2008 and 2017. Clinical, functional, and radiologic records were conducted twice a year. Coronal curve types, segmental measurements, and skeletal maturity were assessed. RESULTS A scoliotic deformity was reported in 71% of the patients at a mean age of 11.7 ± 3.1 years. Average follow-up was 6 years, including 75% of patients with closed triradiate cartilage at latest examination. Mean Cobb angle was 34° ± 2°. Main right thoracic curves were the most frequent curves observed (36%), followed by double major (21%), thoracolumbar and left thoracic curves (13%), main lumbar (11%), and long C-shape curves (6%). Hyperkyphosis (>40°) was present in 66%, with an average kyphosis angle of 50° ± 3°, and anterior misalignment (>5°) occurred in 53%. The severity of the Cobb angle was neither correlated to the FA severity scores nor the age at FA diagnosis. An arthrodesis was performed in 9 patients, including 5 patients (45%) who were ambulatory at least 1 year after surgery. CONCLUSIONS The prevalence of scoliosis in FA was high (71%), and thoracic hyperkyphosis, with anterior misalignment, was frequently observed, which might be related to the anterior imbalance frequently encountered in patients with an ataxia. Posterior fusion including sacral instrumentation was only performed in nonambulatory patients, and the loss of ambulation was not associated with spinal surgery. LEVEL OF EVIDENCE Level IV.
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Affiliation(s)
- Anne Laure Simon
- Department of Pediatric Orthopaedics, Robert Debré Hospital, Assistance Publique-Hôpitaux de Paris (AP-HP), Paris Diderot University, 48 Bd Sérurier, 75019 Paris, France; Motion Analysis Laboratory, Robert Debré Hospital, Assistance Publique-Hôpitaux de Paris (AP-HP), Paris Diderot University, 48 Bd Sérurier, 75019 Paris, France.
| | - Jean Meyblum
- Department of Pediatric Orthopaedics, Robert Debré Hospital, Assistance Publique-Hôpitaux de Paris (AP-HP), Paris Diderot University, 48 Bd Sérurier, 75019 Paris, France
| | - Bastien Roche
- Motion Analysis Laboratory, Robert Debré Hospital, Assistance Publique-Hôpitaux de Paris (AP-HP), Paris Diderot University, 48 Bd Sérurier, 75019 Paris, France
| | - Christophe Vidal
- Department of Pediatric Orthopaedics, Robert Debré Hospital, Assistance Publique-Hôpitaux de Paris (AP-HP), Paris Diderot University, 48 Bd Sérurier, 75019 Paris, France
| | - Keyvan Mazda
- Department of Pediatric Orthopaedics, Robert Debré Hospital, Assistance Publique-Hôpitaux de Paris (AP-HP), Paris Diderot University, 48 Bd Sérurier, 75019 Paris, France
| | - Isabelle Husson
- Department of Functional Rehabilitation, Robert Debré Hospital, Assistance Publique-Hôpitaux de Paris (AP-HP), Paris Diderot University, 48 Bd Sérurier, 75019 Paris, France
| | - Brice Ilharreborde
- Department of Pediatric Orthopaedics, Robert Debré Hospital, Assistance Publique-Hôpitaux de Paris (AP-HP), Paris Diderot University, 48 Bd Sérurier, 75019 Paris, France
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Lecocq C, Charles P, Azulay JP, Meissner W, Rai M, N'Guyen K, Péréon Y, Fabre N, Robin E, Courtois S, Guyant-Maréchal L, Zagnoli F, Rudolf G, Renaud M, Sévin-Allouet M, Lesne F, Alaerts N, Goizet C, Calvas P, Eusebio A, Guissart C, Derkinderen P, Tison F, Brice A, Koenig M, Pandolfo M, Tranchant C, Dürr A, Anheim M. Delayed-onset Friedreich's ataxia revisited. Mov Disord 2015; 31:62-9. [PMID: 26388117 DOI: 10.1002/mds.26382] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2014] [Revised: 06/30/2015] [Accepted: 07/06/2015] [Indexed: 01/21/2023] Open
Abstract
BACKGROUND Friedreich's ataxia usually occurs before the age of 25. Rare variants have been described, such as late-onset Friedreich's ataxia and very-late-onset Friedreich's ataxia, occurring after 25 and 40 years, respectively. We describe the clinical, functional, and molecular findings from a large series of late-onset Friedreich's ataxia and very-late-onset Friedreich's ataxia and compare them with typical-onset Friedreich's ataxia. METHODS Phenotypic and genotypic comparison of 44 late-onset Friedreich's ataxia, 30 very late-onset Friedreich's ataxia, and 180 typical Friedreich's ataxia was undertaken. RESULTS Delayed-onset Friedreich's ataxia (late-onset Friedreich's ataxia and very-late-onset Friedreich's ataxia) had less frequently dysarthria, abolished tendon reflexes, extensor plantar reflexes, weakness, amyotrophy, ganglionopathy, cerebellar atrophy, scoliosis, and cardiomyopathy than typical-onset Friedreich's ataxia, along with less severe functional disability and shorter GAA expansion on the smaller allele (P < 0.001). Delayed-onset Friedreich's ataxia had lower scale for the assessment and rating of ataxia and spinocerebellar degeneration functional scores and longer disease duration before wheelchair confinement (P < 0.001). Both GAA expansions were negatively correlated to age at disease onset (P < 0.001), but the smaller GAA expansion accounted for 62.9% of age at onset variation and the larger GAA expansion for 15.6%. In this comparative study of late-onset Friedreich's ataxia and very-late-onset Friedreich's ataxia, no differences between these phenotypes were demonstrated. CONCLUSION Typical- and delayed-onset Friedreich's ataxia are different and Friedreich's ataxia is heterogeneous. Late-onset Friedreich's ataxia and very-late-onset Friedreich's ataxia appear to belong to the same clinical and molecular continuum and should be considered together as "delayed-onset Friedreich's ataxia." As the most frequently inherited ataxia, Friedreich's ataxia should be considered facing compatible pictures, including atypical phenotypes (spastic ataxia, retained reflexes, lack of dysarthria, and lack of extraneurological signs), delayed disease onset (even after 60 years of age), and/or slow disease progression.
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Affiliation(s)
- Claire Lecocq
- Département de Neurologie, Hôpital de Hautepierre, CHU de Strasbourg, Strasbourg, France
| | - Perrine Charles
- Département de Génétique et Cytogénétique, Hôpital de la Pitié-Salpêtrière, AP-HP, Paris, France
| | - Jean-Philippe Azulay
- Département de Neurologie et Pathologie du mouvement, Hôpital de la Timone, Marseille, France
| | - Wassilios Meissner
- Université De Bordeaux, Institut des Maladies Neurodégénératives, CNRS UMR 5293, Bordeaux, France; and Département de Neurologie, Hôpital Pellegrin, CHU de Bordeaux, Bordeaux, France
| | - Myriam Rai
- Laboratoire de Neurologie Expérimentale, Université Libre de Bruxelles (ULB), Brussels, Belgium
| | - Karine N'Guyen
- Département de Neurologie et Pathologie du mouvement, Hôpital de la Timone, Marseille, France
| | - Yann Péréon
- Laboratoire d'Explorations Fonctionnelles, Centre de Référence Maladies Neuromusculaires Nantes-Angers, Hôtel-Dieu, CHU Nantes, Nantes, France
| | - Nelly Fabre
- Département de Neurologie, Hôpital Purpan, CHU de Toulouse, Toulouse, France
| | - Elsa Robin
- Département de Neurologie et Pathologie du mouvement, Hôpital de la Timone, Marseille, France
| | - Sylvie Courtois
- Département de Neurologie, Hôpital Emile-Muller, Mulhouse, France
| | | | | | - Gabrielle Rudolf
- Département de Neurologie, Hôpital de Hautepierre, CHU de Strasbourg, Strasbourg, France
| | - Mathilde Renaud
- Département de Neurologie, Hôpital de Hautepierre, CHU de Strasbourg, Strasbourg, France
| | | | - Fabien Lesne
- UPMC Université Paris 06, UMR_S975, Centre de Recherche Institut du Cerveau et de la Moelle, CNRS 7225, Hôpital de la Pitié-Salpêtrière, Paris, France; and INSERM, UMR_S975, Paris, France
| | - Nick Alaerts
- Laboratoire de Neurologie Expérimentale, Université Libre de Bruxelles (ULB), Brussels, Belgium
| | - Cyril Goizet
- CHU Bordeaux, Service de Génétique Médicale, Université Bordeaux, Laboratoire Maladies Rares: Génétique et Métabolisme (MRGM), EA4576, Bordeaux, France
| | - Patrick Calvas
- Département de Neurologie, Hôpital Purpan, CHU de Toulouse, Toulouse, France; and Service de Génétique Médicale, Hôpital Purpan, CHU de Toulouse, Toulouse, France
| | - Alexandre Eusebio
- Département de Neurologie et Pathologie du mouvement, Hôpital de la Timone, Marseille, France
| | - Claire Guissart
- Laboratoire de Génétique Moléculaire, Institut Universitaire de Recherche Clinique, Université de Montpellier, CHU Montpellier, Montpellier, France
| | - Pascal Derkinderen
- Département de Neurologie, Hôpital GR Laënnec, CHU de Nantes, Nantes, France
| | - Francois Tison
- Université De Bordeaux, Institut des Maladies Neurodégénératives, CNRS UMR 5293, Bordeaux, France; and Département de Neurologie, Hôpital Pellegrin, CHU de Bordeaux, Bordeaux, France
| | - Alexis Brice
- Département de Génétique et Cytogénétique, Hôpital de la Pitié-Salpêtrière, AP-HP, Paris, France; UPMC Université Paris 06, UMR_S975, Centre de Recherche Institut du Cerveau et de la Moelle, CNRS 7225, Hôpital de la Pitié-Salpêtrière, Paris, France; and INSERM, UMR_S975, Paris, France
| | - Michel Koenig
- Laboratoire de Génétique Moléculaire, Institut Universitaire de Recherche Clinique, Université de Montpellier, CHU Montpellier, France; and Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), INSERM-U964/CNRS-UMR7104/Université de Strasbourg, Illkirch, France
| | - Massimo Pandolfo
- Laboratoire de Neurologie Expérimentale, Université Libre de Bruxelles (ULB), Brussels, Belgium; and Département de Neurologie, Hôpital Erasme, Brussels, Belgium
| | - Christine Tranchant
- Département de Neurologie, Hôpital de Hautepierre, CHU de Strasbourg, Strasbourg, France; Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), INSERM-U964/CNRS-UMR7104/Université de Strasbourg, Illkirch, France; and Fédération de Médecine Translationnelle de Strasbourg (FMTS), Université de Strasbourg, Strasbourg, France
| | - Alexandra Dürr
- Département de Génétique et Cytogénétique, Hôpital de la Pitié-Salpêtrière, AP-HP, Paris, France; UPMC Université Paris 06, UMR_S975, Centre de Recherche Institut du Cerveau et de la Moelle, CNRS 7225, Hôpital de la Pitié-Salpêtrière, Paris, France; and INSERM, UMR_S975, Paris, France
| | - Mathieu Anheim
- Département de Neurologie, Hôpital de Hautepierre, CHU de Strasbourg, France Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), INSERM-U964/CNRS-UMR7104/Université de Strasbourg, Illkirch, France; and Fédération de Médecine Translationnelle de Strasbourg (FMTS), Université de Strasbourg, Strasbourg, France
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Wedding IM, Kroken M, Henriksen SP, Selmer KK, Fiskerstrand T, Knappskog PM, Berge T, Tallaksen CME. Friedreich ataxia in Norway - an epidemiological, molecular and clinical study. Orphanet J Rare Dis 2015; 10:108. [PMID: 26338206 PMCID: PMC4559212 DOI: 10.1186/s13023-015-0328-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Accepted: 08/25/2015] [Indexed: 01/06/2023] Open
Abstract
Background Friedreich ataxia is an autosomal recessive hereditary spinocerebellar disorder, characterized by progressive limb and gait ataxia due to proprioceptive loss, often complicated by cardiomyopathy, diabetes and skeletal deformities. Friedreich ataxia is the most common hereditary ataxia, with a reported prevalence of 1:20 000 – 1:50 000 in Central Europe. Previous reports from south Norway have found a prevalence varying from 1:100 000 – 1:1 350 000; no studies are previously done in the rest of the country. Methods In this cross-sectional study, Friedreich ataxia patients were identified through colleagues in neurological, pediatric and genetic departments, hospital archives searches, patients’ associations, and National Centre for Rare Disorders. All included patients, carriers and controls were investigated clinically and molecularly with genotype characterization including size determination of GAA repeat expansions and frataxin measurements. 1376 healthy blood donors were tested for GAA repeat expansion for carrier frequency analysis. Results Twenty-nine Friedreich ataxia patients were identified in Norway, of which 23 were ethnic Norwegian, corresponding to a prevalence of 1:176 000 and 1:191 000, respectively. The highest prevalence was seen in the north. Carrier frequency of 1:196 (95 % CI = [1:752–1:112]) was found. Homozygous GAA repeat expansions in the FXN gene were found in 27/29, while two patients were compound heterozygous with c.467 T < C, L157P and the deletion (g.120032_122808del) including exon 5a. Two additional patients were heterozygous for GAA repeat expansions only. Significant differences in the level of frataxin were found between the included patients (N = 27), carriers (N = 37) and controls (N = 27). Conclusions In this first thorough study of a complete national cohort of Friedreich ataxia patients, and first nation-wide study of Friedreich ataxia in Norway, the prevalence of Friedreich ataxia in Norway is lower than in Central Europe, but higher than in the last Norwegian report, and as expected from migration studies. A south–north prevalence gradient is present. Based on Hardy Weinberg’s equilibrium, the carrier frequency of 1:196 is consistent with the observed prevalence. All genotypes, and typical and atypical phenotypes were present in the Norwegian population. The patients were phenotypically similar to European cohorts. Frataxin was useful in the diagnostic work-up of heterozygous symptomatic cases. Electronic supplementary material The online version of this article (doi:10.1186/s13023-015-0328-4) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Iselin Marie Wedding
- Department of Neurology, Oslo University Hospital, Ullevaal, 0407, Oslo, Norway. .,University of Oslo, Faculty of Medicine, Oslo, Norway.
| | - Mette Kroken
- Department of Medical Genetics, Oslo University Hospital, Ullevaal, 0407, Oslo, Norway
| | | | - Kaja Kristine Selmer
- Department of Medical Genetics, Oslo University Hospital, Ullevaal, 0407, Oslo, Norway.,University of Oslo, Faculty of Medicine, Oslo, Norway
| | - Torunn Fiskerstrand
- Department of Clinical Science, University of Bergen, Bergen, Norway.,Center for Medical Genetics and Molecular Medicine, Haukeland University Hospital, Bergen, Norway
| | - Per Morten Knappskog
- Department of Clinical Science, University of Bergen, Bergen, Norway.,Center for Medical Genetics and Molecular Medicine, Haukeland University Hospital, Bergen, Norway
| | - Tone Berge
- Department of Neurology, Oslo University Hospital, Ullevaal, 0407, Oslo, Norway
| | - Chantal M E Tallaksen
- Department of Neurology, Oslo University Hospital, Ullevaal, 0407, Oslo, Norway.,University of Oslo, Faculty of Medicine, Oslo, Norway
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Germanotta M, Vasco G, Petrarca M, Rossi S, Carniel S, Bertini E, Cappa P, Castelli E. Robotic and clinical evaluation of upper limb motor performance in patients with Friedreich's Ataxia: an observational study. J Neuroeng Rehabil 2015; 12:41. [PMID: 25900021 PMCID: PMC4448881 DOI: 10.1186/s12984-015-0032-6] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Accepted: 04/10/2015] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Friedreich's ataxia (FRDA) is the most common hereditary autosomal recessive form of ataxia. In this disease there is early manifestation of gait ataxia, and dysmetria of the arms and legs which causes impairment in daily activities that require fine manual dexterity. To date there is no cure for this disease. Some novel therapeutic approaches are ongoing in different steps of clinical trial. Development of sensitive outcome measures is crucial to prove therapeutic effectiveness. The aim of the study was to assess the reliability and sensitivity of quantitative and objective assessment of upper limb performance computed by means of the robotic device and to evaluate the correlation with clinical and functional markers of the disease severity. METHODS Here we assess upper limb performances by means of the InMotion Arm Robot, a robot designed for clinical neurological applications, in a cohort of 14 children and young adults affected by FRDA, matched for age and gender with 18 healthy subjects. We focused on the analysis of kinematics, accuracy, smoothness, and submovements of the upper limb while reaching movements were performed. The robotic evaluation of upper limb performance consisted of planar reaching movements performed with the robotic system. The motors of the robot were turned off, so that the device worked as a measurement tool. The status of the disease was scored using the Scale for the Assessment and Rating of Ataxia (SARA). Relationships between robotic indices and a range of clinical and disease characteristics were examined. RESULTS All our robotic indices were significantly different between the two cohorts except for two, and were highly and reliably discriminative between healthy and subjects with FRDA. In particular, subjects with FRDA exhibited slower movements as well as loss of accuracy and smoothness, which are typical of the disease. Duration of Movement, Normalized Jerk, and Number of Submovements were the best discriminative indices, as they were directly and easily measurable and correlated with the status of the disease, as measured by SARA. CONCLUSIONS Our results suggest that outcome measures obtained by means of robotic devices can improve the sensitivity of clinical evaluations of patients' dexterity and can accurately and efficiently quantify changes over time in clinical trials, particularly when functional scales appear to be no longer sensitive.
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Affiliation(s)
- Marco Germanotta
- Don Carlo Gnocchi Onlus Foundation, Piazzale Morandi 6, 20121, Milan, Italy.
| | - Gessica Vasco
- Movement Analysis and Robotics Laboratory (MARLab), Neurorehabilitation Units, IRCCS Bambino Gesù Children's Hospital, Via Torre di Palidoro, 00050, Passoscuro (Fiumicino), Rome, Italy. .,Unit of Neuromuscular and Neurodegenerative Disorders, Laboratory of Molecular Medicine, IRCCS Bambino Gesù Children's Hospital, Piazza S. Onofrio 4, 00165, Rome, Italy.
| | - Maurizio Petrarca
- Movement Analysis and Robotics Laboratory (MARLab), Neurorehabilitation Units, IRCCS Bambino Gesù Children's Hospital, Via Torre di Palidoro, 00050, Passoscuro (Fiumicino), Rome, Italy.
| | - Stefano Rossi
- Department of Economics and Management - Industrial Engineering (DEIM), University of Tuscia, Via del Paradiso 47, 01100, Viterbo, Italy.
| | - Sacha Carniel
- Movement Analysis and Robotics Laboratory (MARLab), Neurorehabilitation Units, IRCCS Bambino Gesù Children's Hospital, Via Torre di Palidoro, 00050, Passoscuro (Fiumicino), Rome, Italy.
| | - Enrico Bertini
- Unit of Neuromuscular and Neurodegenerative Disorders, Laboratory of Molecular Medicine, IRCCS Bambino Gesù Children's Hospital, Piazza S. Onofrio 4, 00165, Rome, Italy.
| | - Paolo Cappa
- Movement Analysis and Robotics Laboratory (MARLab), Neurorehabilitation Units, IRCCS Bambino Gesù Children's Hospital, Via Torre di Palidoro, 00050, Passoscuro (Fiumicino), Rome, Italy. .,Department of Mechanical and Aerospace Engineering, "Sapienza", University of Rome, Via Eudossiana 18, 00184, Roma, Italy.
| | - Enrico Castelli
- Movement Analysis and Robotics Laboratory (MARLab), Neurorehabilitation Units, IRCCS Bambino Gesù Children's Hospital, Via Torre di Palidoro, 00050, Passoscuro (Fiumicino), Rome, Italy.
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9
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Boesch S, Nachbauer W, Mariotti C, Sacca F, Filla A, Klockgether T, Klopstock T, Schöls L, Jacobi H, Büchner B, vom Hagen JM, Nanetti L, Manicom K. Safety and tolerability of carbamylated erythropoietin in Friedreich's ataxia. Mov Disord 2014; 29:935-9. [PMID: 24515352 DOI: 10.1002/mds.25836] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2013] [Revised: 11/12/2013] [Accepted: 12/09/2013] [Indexed: 01/06/2023] Open
Abstract
BACKGROUND Erythropoietin (EPO) derivatives have been found to increase frataxin levels in Friedreich's ataxia (FRDA) in vitro. This multicenter, double-blind, placebo-controlled, phase II clinical trial aimed to evaluate the safety and tolerability of Lu AA24493 (carbamylated EPO; CEPO). METHODS Thirty-six ambulatory FRDA patients harboring >400 GAA repeats were 2:1 randomly assigned to either CEPO in a fixed dose (325 µg thrice-weekly) or placebo. Safety and tolerability were assessed up to 103 days after baseline. Secondary outcome measures of efficacy (exploration of biomarkers and ataxia ratings) were performed up to 43 days after baseline. RESULTS All patients received six doses of study medication. Adverse events were equally distributed between CEPO and placebo. There was no evidence for immunogenicity of CEPO after multiple dosing. Biomarkers, such as frataxin, or measures for oxidative stress and ataxia ratings did not differ between CEPO and placebo. CONCLUSION CEPO was safe and well tolerated in a 2-week treatment phase. Secondary outcome measures remained without apparent difference between CEPO and placebo.
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Affiliation(s)
- Sylvia Boesch
- Department of Neurology, Medical University Innsbruck, Innsbruck, Austria
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10
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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: 168] [Impact Index Per Article: 15.3] [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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11
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Abstract
Friedreich ataxia, the most common inherited ataxia, is caused by the transcriptional silencing of the FXN gene, which codes for the 210 amino acid frataxin, a mitochondrial protein involved in iron-sulfur cluster biosynthesis. The expansion of the GAA x TTC tract in intron 1 to as many as 1700 repeats elicits the transcriptional silencing by the formation of non-B DNA structures (triplexes or sticky DNA), the formation of a persistent DNA x RNA hybrid, or heterochromatin formation. The triplex (sticky DNA) adopted by the long repeat sequence also elicits profound mutagenic, genetic instability, and recombination behaviors. Early stage therapeutic investigations involving polyamides or histone deacetylase inhibitors are being pursued. Friedreich ataxia may be one of the most thoroughly studied hereditary neurological disease from a pathophysiological standpoint.
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Affiliation(s)
- Robert D Wells
- Center for Genome Research, Institute of Biosciences and Technology, Texas A&M University System Health Science Center, The Texas Medical Center, 2121 W. Holcombe Blvd., Houston, TX 77030-3303, USA.
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12
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Fogel BL, Perlman S. Clinical features and molecular genetics of autosomal recessive cerebellar ataxias. Lancet Neurol 2007; 6:245-57. [PMID: 17303531 DOI: 10.1016/s1474-4422(07)70054-6] [Citation(s) in RCA: 178] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Among the hereditary ataxias, autosomal recessive spinocerebellar ataxias comprise a diverse group of neurodegenerative disorders. Clinical phenotypes vary from predominantly cerebellar syndromes to sensorimotor neuropathy, ophthalmological disturbances, involuntary movements, seizures, cognitive dysfunction, skeletal anomalies, and cutaneous disorders, among others. Molecular pathogenesis also ranges from disorders of mitochondrial or cellular metabolism to impairments of DNA repair or RNA processing functions. Diagnosis can be improved by a systematic approach to the categorisation of these disorders, which is used to direct further, more specific, biochemical and genetic investigations. In this Review, we discuss the clinical characteristics and molecular genetics of the more common autosomal recessive ataxias and provide a framework for assessment and differential diagnosis of patients with these disorders.
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Affiliation(s)
- Brent L Fogel
- Department of Neurology, David Geffen School of Medicine at UCLA, University of California at Los Angeles, 90095, USA
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13
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Land JM, Heales SJR, Duncan AJ, Hargreaves IP. Some Observations upon Biochemical Causes of Ataxia and a New Disease Entity Ubiquinone, CoQ10 Deficiency. Neurochem Res 2006; 32:837-43. [PMID: 17186372 DOI: 10.1007/s11064-006-9222-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2006] [Accepted: 11/06/2006] [Indexed: 11/29/2022]
Abstract
Some hereditary ataxias are treatable and the insight required for this has come from an in depth knowledge of the phenotypes and clinical biochemistry of the conditions. This has required both fundamental and translational clinical research. Prof John Blass was fortunate to begin his career at what we can now recognise as a golden era for such studies and he worked upon two important conditions; Refsum's disease and Friedreich's ataxia. More recently the mitochondrial encephalomyopathies have been described and similar investigative work has been undertaken upon them. Ubiquinone, CoQ(10), deficiency is the most recently recognised encephalomyopathy and is itself treatable. Though rare, it is becoming increasingly recognised and patients are benefiting from the same scholarly approach to its investigation as was afforded Refsums' disease and Friedreich's ataxia.
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Affiliation(s)
- John M Land
- Neurometabolic Unit Box 105, National Hospital for Neurology & Neurosurgery, Queen Square, London, WC1N 3BG, UK.
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14
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Son LS, Bacolla A, Wells RD. Sticky DNA: in vivo formation in E. coli and in vitro association of long GAA*TTC tracts to generate two independent supercoiled domains. J Mol Biol 2006; 360:267-84. [PMID: 16764889 DOI: 10.1016/j.jmb.2006.05.025] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2006] [Revised: 05/04/2006] [Accepted: 05/10/2006] [Indexed: 02/02/2023]
Abstract
The expanded GAA*TTC repeat sequence associated with Friedreich's ataxia (FRDA) adopts non-B DNA structures, (triplexes and sticky DNA). Sticky DNA is formed in plasmids by the association of two long GAA*TTC tracts at lengths that are found in the sequence of the frataxin gene in patients. Most FRDA patients have expanded GAA*TTC repeats (up to 1700 triplets), which inhibit the transcription of the gene, thus diminishing the synthesis of frataxin, a mitochondrial protein involved in iron-sulfur cluster biogenesis. Negative supercoiling and MgCl(2) (or MnCl(2)) are required to stabilize sticky DNA (a dumbbell-shaped structure) in plasmids with a pair of repeat tracts where n> or =60 in the direct repeat orientation in vitro. Since the triplet repeat sequences (TRS) were symmetrically positioned in the plasmids and because a number of unique restriction sites were present in the vector, studies were conducted to evaluate the influence of selectively linearizing one or the other supercoiled domains created by the DNA*DNA associated region, i.e. the stable complex at the pair of TRS's. The two domains behave independently, thus confirming the association of the two tracts and the dumbbell-shaped plasmid in our model for sticky DNA. Linking number investigations were performed on a family of plasmids harboring different lengths (30, 60, or 176 repeats), orientations and number of tracts (one or two) of a GAA*TTC repeat in Escherichia coli to evaluate the in vivo role, if any, of sticky DNA. Unexpectedly, this non-B DNA conformation elicited the formation of a TRS-length dependent change in the global topology of the plasmids, indicative of an apparent compression of the primary helices. Thus, linking number determinations confirm that sticky DNA has an important consequence in vivo.
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Affiliation(s)
- Leslie S Son
- Institute of Biosciences and Technology, Center for Genome Research, Texas A&M University System Health Science Center, Texas Medical Center, 2121 W. Holcombe Blvd., Houston, TX 77030-3303, USA
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15
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Di Prospero NA, Fischbeck KH. Therapeutics development for triplet repeat expansion diseases. Nat Rev Genet 2005; 6:756-65. [PMID: 16205715 DOI: 10.1038/nrg1690] [Citation(s) in RCA: 113] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The underlying genetic mutations for many inherited neurodegenerative disorders have been identified in recent years. One frequent type of mutation is trinucleotide repeat expansion. Depending on the location of the repeat expansion, the mutation might result in a loss of function of the disease gene, a toxic gain of function or both. Disease gene identification has led to the development of model systems for investigating disease mechanisms and evaluating treatments. Examination of experimental findings reveals similarities in disease mechanisms as well as possibilities for treatment.
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Affiliation(s)
- Nicholas A Di Prospero
- Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20892-3705, USA.
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16
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Ventura N, Rea S, Henderson ST, Condo I, Johnson TE, Testi R. Reduced expression of frataxin extends the lifespan of Caenorhabditis elegans. Aging Cell 2005; 4:109-12. [PMID: 15771615 DOI: 10.1111/j.1474-9726.2005.00149.x] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Defects in the expression of the mitochondrial protein frataxin cause Friedreich's ataxia, an hereditary neurodegenerative syndrome characterized by progressive ataxia and associated with reduced life expectancy in humans. Homozygous inactivation of the frataxin gene results in embryonic lethality in mice, suggesting that frataxin is required for organismic survival. Intriguingly, the inactivation of many mitochondrial genes in the nematode Caenorhabditis elegans by RNAi extends lifespan. We therefore investigated whether inactivation of frataxin by RNAi-mediated suppression of the frataxin homolog gene (frh-1) would also prolong lifespan in the nematode. Frataxin-deficient animals have a small body size, reduced fertility and altered responses to oxidative stress. Importantly, frataxin suppression by RNAi significantly extends lifespan in C. elegans.
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Affiliation(s)
- Natascia Ventura
- Institute for Behavioral Genetics, University of Colorado at Boulder, Box 447 Boulder, CO 80309-0447 USA
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17
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Subramony SH. GENETICS OF INHERITED ATAXIAS. Continuum (Minneap Minn) 2005. [DOI: 10.1212/01.con.0000293702.31088.0d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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18
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Affiliation(s)
- Clemens R Scherzer
- Department of Pathology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
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19
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Ruggiero BL, Topal MD. Triplet repeat expansion generated by DNA slippage is suppressed by human flap endonuclease 1. J Biol Chem 2004; 279:23088-97. [PMID: 15037629 DOI: 10.1074/jbc.m313170200] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Human flap endonuclease 1 (h-FEN1) mutations have dramatic effects on repeat instability. Current models for repeat expansion predict that h-FEN1 protein prevents mutations by removing 5'-flaps generated at ends of Okazaki fragments by strand displacement synthesis. The models propose that hairpin formations within flaps containing repeats enable them to escape h-FEN1 cleavage. Friedreich's ataxia is caused by expansion mutations in a d(GAA)n repeat tract. Single-stranded d(GAA)n repeat tracts, however, do not form stable hairpins until the repeat tracts are quite long. Therefore, to understand how d(GAA)n repeat expansions survive h-FEN1 activity, we determined the effects of h-FEN1 on d(GAA)n repeat expansion during replication of a d(TTC)n repeat template. Replication initiated within the repeat tract generated significant expansion that was suppressed by the addition of h-FEN1 at the start of replication. The ability of h-FEN1 to suppress expansion implies that DNA slippage generates a 5'-flap in the nascent strand independent of strand displacement synthesis by an upstream polymerase. Delaying the addition of h-FEN1 to the replication reaction abolished the ability of h-FEN1 ability to suppress d(GAA)n repeat expansion products of all sizes, including sizes unable to hairpin. Use of model substrates demonstrated that h-FEN1 cleaves d(GAA)n 5'-flaps joined to double-stranded nonrepeat sequences but not those joined to double-stranded repeat tracts. The results provide evidence that, given the opportunity, short d(GAA)n repeat expansion products rearrange from 5'-flaps to stable internal loops inside the repeat tract. Long expansion products are predicted to form hairpinned flaps and internal loops. Once formed, these DNA conformations resist h-FEN1. The biological implications of the results are discussed.
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Affiliation(s)
- Bethany L Ruggiero
- Lineberger Comprehensive Cancer Center, University of North Carolina Medical School, Chapel Hill, North Carolina 27599-7295, USA
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20
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Greene E, Handa V, Kumari D, Usdin K. Transcription defects induced by repeat expansion: fragile X syndrome, FRAXE mental retardation, progressive myoclonus epilepsy type 1, and Friedreich ataxia. Cytogenet Genome Res 2003; 100:65-76. [PMID: 14526165 DOI: 10.1159/000072839] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2002] [Accepted: 02/06/2003] [Indexed: 11/19/2022] Open
Abstract
Fragile X mental retardation syndrome, FRAXE mental retardation, Progressive myoclonus epilepsy Type I, and Friedreich ataxia are members of a larger group of genetic disorders known as the Repeat Expansion Diseases. Unlike other members of this group, these four disorders all result from a primary defect in the initiation or elongation of transcription. In this review, we discuss current models for the relationship between the expanded repeat and the disease symptoms.
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Affiliation(s)
- E Greene
- Section on Genomic Structure and Function, Laboratory of Molecular and Cellular Biology, National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0830, USA
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22
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Abstract
PURPOSE OF REVIEW The present review covers recent developments in inherited ataxias. The discovery of new loci and genes has led to improved understanding of the breadth and epidemiology of inherited ataxias. This has resulted also in more rational classification schemes. Research on identified loci has begun to yield insights into the pathogenesis of neuronal dysfunction and neurodegeneration in these diseases. RECENT FINDINGS There are a plethora of inherited ataxias due to a variety of mutational mechanisms involving numerous loci. While ataxia and other aspects of cerebellar dysfunction are the core features of these diseases, rational classification has been impeded by the simultaneous variety of associated clinical features and considerable overlap in clinical features among diseases involving different loci. Inherited ataxias can be classified according to mode of inheritance and mechanism of mutations. Dominantly inherited ataxias (spinocerebellar ataxias) are one major group of ataxias. Spinocerebellar ataxias can be subdivided into expanded exonic CAG repeat (polyglutamine; polyQ) disorders, dominantly inherited ataxias with mutations in non-coding regions, and dominantly inherited ataxias with chromosomal localizations but unidentified loci. Another group of dominantly inherited ataxias are episodic ataxias due to ion channel mutations. Recessive ataxias constitute a more heterogeneous group due to loss-of-function effects in numerous loci. A number of these loci have now been identified. Progress has been made in investigating the pathogenesis of neuronal dysfunction/neurodegeneration in several inherited ataxias. Convergent evidence suggests that transcriptional dysregulation is an important component of neurodegeneration in polyQ disorders. Mitochondrial dysfunction is central to pathogenesis of the most common recessive ataxia, Friedreich ataxia. SUMMARY Mapping of additional ataxia loci and identification of novel ataxia genes continues unabated. Genetic classification enables typology of inherited ataxias. Identification of the affected loci and the mutational mechanisms has allowed the first glimmers of understanding of the pathogenesis of several inherited ataxias.
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Affiliation(s)
- Roger L Albin
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109, USA.
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Abstract
Since the discovery of the gene mutation causing Friedreich's ataxia (FA), the rich spectrum of clinical manifestations of this autosomal recessive disorder is being increasingly recognized. Movement disorders besides ataxia, however, have not been fully characterized in patients with FA. We describe here two young male patients who, in addition to progressive ataxia, kinetic tremor and other typical features of FA, also manifest axial and limb dystonia. The primary purpose of this report is to draw attention to the broad spectrum of hyperkinetic movement disorders that can present as or be associated with FA.
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Affiliation(s)
- Jyh-Gong Gabriel Hou
- Parkinson's Disease Center and Movement Disorders Clinic, Department of Neurology, Baylor College of Medicine, 6550 Fannin, #1801, Houston, TX 77030, USA
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Pandolfo M. Frataxin deficiency and mitochondrial dysfunction. Mitochondrion 2002; 2:87-93. [PMID: 16120311 DOI: 10.1016/s1567-7249(02)00039-9] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2002] [Revised: 04/25/2002] [Accepted: 05/01/2002] [Indexed: 02/01/2023]
Abstract
Friedreich ataxia (FA) is an inherited recessive disorder characterized by progressive neurological disability and heart abnormalities. The Friedreich ataxia gene (FRDA) encodes a small mitochondrial protein, frataxin, which is produced in insufficient amounts in the disease as a consequence of a GAA triplet repeat expansion in the first intron of the gene. Frataxin deficiency leads to excessive free radical production, dysfunction of Fe-S center containing enzymes (in particular respiratory complexes I, II and III, and aconitase), and progressive iron accumulation in mitochondria. Frataxin may be a mitochondrial iron-binding protein that prevents this metal from participating in Fenton chemistry to generate toxic hydroxyl radicals. We investigated whether frataxin deficiency may in addition interfere with signaling pathways. First, we showed that exposure of FA fibroblasts to iron fails to produce the normally observed increase in expression of the stress defense protein manganese superoxide dismutase. This impaired induction involves a nuclear factor-kappaB-independent pathway that does not require free radical signaling intermediates. We also examined the role of frataxin in neuronal differentiation by using stably transfected clones of P19 embryonic carcinoma cells with antisense or sense frataxin constructs. We found that during retinoic acid-induced neurogenesis frataxin deficiency enhances apoptosis and reduces the number of terminally differentiated neuronal-like cells. The addition of the antioxidant N-acetyl-cysteine only rescues cells non-committed to the neuronal lineage, indicating that frataxin deficiency impairs differentiation mechanisms and survival responses through different mechanisms. Both studies suggest that some abnormalities in frataxin-deficient cells are related to free radical independent signaling pathways.
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Affiliation(s)
- Massimo Pandolfo
- Université Libre de Bruxelles-Hôpital Erasme, Service de Neurologie, Route de Lennik 808, B-1070 Brussels, Belgium.
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Paulson HL. Diagnostic testing in neurogenetics. Principles, limitations, and ethical considerations. Neurol Clin 2002; 20:627-43, v. [PMID: 12432824 DOI: 10.1016/s0733-8619(02)00009-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Genetics has emphatically entered the practice of neurology. The last decade witnessed the discovery of the genetic basis of many diseases that primarily affect the nervous system. In areas such as neuromuscular and movement disorders, genetic testing has become a routine part of diagnostic testing. In areas like epilepsy, genetic advances likely will lead to new testing for certain patients. In dementia, the existence of a common predisposing genetic factor (apolipoprotein E) has already raised complex issues such as the appropriateness of genetic testing in specific clinical situations--issues that neurologists will confront more in the future. This article reviews basic principles of genetic testing, its application to neurology, and some limitations and ethical issues confronting the field.
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Affiliation(s)
- Henry L Paulson
- Department of Neurology, University of Iowa School of Medicine, Iowa City, IA 52242, USA.
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Abstract
Advances in molecular genetics have led to identification of an increasing number of genes responsible for inherited ataxic disorders. Consequently, DNA testing has become a powerful method to unambiguously establish the diagnosis in some of these disorders; however, there are limitations in this approach. Furthermore, the ethical, social, legal and psychological implications of the genetic test results are complex, necessitating appropriate counseling. This article intends to help the practicing neurologist clinically differentiate these disorders, choose appropriate genetic tests, and recognize the importance of counseling.
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Affiliation(s)
- Alberto L Rosa
- Universidad de Córdoba, Laboratory of Neurogenetics, Institute for Medical Research Mercedes y Martín Ferreyra-INIMEC, Carrer Researcher of the National Research Council (CONICET), Córdoba, Argentina
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