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Thymidine Kinase 2 and Mitochondrial Protein COX I in the Cerebellum of Patients with Spinocerebellar Ataxia Type 31 Caused by Penta-nucleotide Repeats (TTCCA) n. CEREBELLUM (LONDON, ENGLAND) 2023; 22:70-84. [PMID: 35084690 PMCID: PMC9883315 DOI: 10.1007/s12311-021-01364-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Accepted: 12/23/2021] [Indexed: 02/01/2023]
Abstract
Spinocerebellar ataxia type 31 (SCA31), an autosomal-dominant neurodegenerative disorder characterized by progressive cerebellar ataxia with Purkinje cell degeneration, is caused by a heterozygous 2.5-3.8 kilobase penta-nucleotide repeat of (TTCCA)n in intron 11 of the thymidine kinase 2 (TK2) gene. TK2 is an essential mitochondrial pyrimidine-deoxyribonucleoside kinase. Bi-allelic loss-of-function mutations of TK2 lead to mitochondrial DNA depletion syndrome (MDS) in humans through severe (~ 70%) reduction of mitochondrial electron-transport-chain activity, and tk2 knockout mice show Purkinje cell degeneration and ataxia through severe mitochondrial cytochrome-c oxidase subunit I (COX I) protein reduction. To clarify whether TK2 function is altered in SCA31, we investigated TK2 and COX I expression in human postmortem SCA31 cerebellum. We confirmed that canonical TK2 mRNA is transcribed from exons far upstream of the repeat site, and demonstrated that an extended version of TK2 mRNA ("TK2-EXT"), transcribed from exons spanning the repeat site, is expressed in human cerebellum. While canonical TK2 was conserved among vertebrates, TK2-EXT was specific to primates. Reverse transcription-PCR demonstrated that both TK2 mRNAs were preserved in SCA31 cerebella compared with control cerebella. The TK2 proteins, assessed with three different antibodies including our original polyclonal antibody against TK2-EXT, were detected as ~ 26 kilodalton proteins on western blot; their levels were similar in SCA31 and control cerebella. COX I protein level was preserved in SCA31 compared to nuclear DNA-encoded protein. We conclude that the expression and function of TK2 are preserved in SCA31, suggesting a mechanism distinct from that of MDS.
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Domínguez-González C, Madruga-Garrido M, Mavillard F, Garone C, Aguirre-Rodríguez FJ, Donati MA, Kleinsteuber K, Martí I, Martín-Hernández E, Morealejo-Aycinena JP, Munell F, Nascimento A, Kalko SG, Sardina MD, Álvarez Del Vayo C, Serrano O, Long Y, Tu Y, Levin B, Thompson JLP, Engelstad K, Uddin J, Torres-Torronteras J, Jimenez-Mallebrera C, Martí R, Paradas C, Hirano M. Deoxynucleoside Therapy for Thymidine Kinase 2-Deficient Myopathy. Ann Neurol 2019; 86:293-303. [PMID: 31125140 DOI: 10.1002/ana.25506] [Citation(s) in RCA: 61] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2018] [Revised: 05/21/2019] [Accepted: 05/22/2019] [Indexed: 12/22/2022]
Abstract
OBJECTIVE Thymidine kinase 2, encoded by the nuclear gene TK2, is required for mitochondrial DNA maintenance. Autosomal recessive TK2 mutations cause depletion and multiple deletions of mtDNA that manifest predominantly as a myopathy usually beginning in childhood and progressing relentlessly. We investigated the safety and efficacy of deoxynucleoside monophosphate and deoxynucleoside therapies. METHODS We administered deoxynucleoside monophosphates and deoxynucleoside to 16 TK2-deficient patients under a compassionate use program. RESULTS In 5 patients with early onset and severe disease, survival and motor functions were better than historically untreated patients. In 11 childhood and adult onset patients, clinical measures stabilized or improved. Three of 8 patients who were nonambulatory at baseline gained the ability to walk on therapy; 4 of 5 patients who required enteric nutrition were able to discontinue feeding tube use; and 1 of 9 patients who required mechanical ventilation became able to breathe independently. In motor functional scales, improvements were observed in the 6-minute walk test performance in 7 of 8 subjects, Egen Klassifikation in 2 of 3, and North Star Ambulatory Assessment in all 5 tested. Baseline elevated serum growth differentiation factor 15 levels decreased with treatment in all 7 patients tested. A side effect observed in 8 of the 16 patients was dose-dependent diarrhea, which did not require withdrawal of treatment. Among 12 other TK2 patients treated with deoxynucleoside, 2 adults developed elevated liver enzymes that normalized following discontinuation of therapy. INTERPRETATION This open-label study indicates favorable side effect profiles and clinical efficacy of deoxynucleoside monophosphate and deoxynucleoside therapies for TK2 deficiency. ANN NEUROL 2019;86:293-303.
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Affiliation(s)
- Cristina Domínguez-González
- Neuromuscular Disorders Unit, Neurology Department, Hospital 12 de Octubre, Madrid, Spain.,Instituto de Investigación i + 12, Hospital 12 de Octubre, Madrid, Spain.,Center for Biomedical Network Research on Rare Diseases (CIBERER), Instituto de Salud Carlos III, Madrid, Spain
| | - Marcos Madruga-Garrido
- Neuromuscular Disorders Unit, Pediatric Neurology Department, Instituto de Biomedicina de Sevilla, Hospital U. Virgen del Rocío, Consejo Superior de Investigaciones Científicas, University of Seville, Seville, Spain
| | - Fabiola Mavillard
- Neuromuscular Disorders Unit, Neurology Department, Instituto de Biomedicina de Sevilla, Hospital U. Virgen del Rocío, Consejo Superior de Investigaciones Científicas, University of Seville, Seville, Spain.,Center for Biomedical Network Research on Neurodegenerative Diseases, Instituto de Salud Carlos III, Madrid, Spain
| | - Caterina Garone
- Medical Research Council Mitochondrial Biology Unit, Cambridge Biomedical Campus, Cambridge, UK
| | | | - M Alice Donati
- Metabolic and Neuromuscular Unit, Meyer Hospital, Florence, Italy
| | - Karin Kleinsteuber
- Pediatric Neurology Department, Faculty of Medicine, University of Chile, Las Condes Clinic, Santiago, Chile
| | - Itxaso Martí
- Pediatric Neurology Department, Donostia University Hospital, San Sebastian, Spain
| | - Elena Martín-Hernández
- Instituto de Investigación i + 12, Hospital 12 de Octubre, Madrid, Spain.,Center for Biomedical Network Research on Rare Diseases (CIBERER), Instituto de Salud Carlos III, Madrid, Spain.,Hereditary Metabolic and Mitochondrial Disorders Unit, Pediatric Department, October 12 Hospital, Madrid, Spain
| | | | - Francina Munell
- Pediatric Department, Vall d'Hebron Hospital, Barcelona, Spain
| | - Andrés Nascimento
- Center for Biomedical Network Research on Rare Diseases (CIBERER), Instituto de Salud Carlos III, Madrid, Spain.,Neuromuscular Unit, Neurology Department, Sant Joan de Déu Research Institute, Sant Joan de Déu Hospital, Barcelona, Spain
| | - Susana G Kalko
- Center for Biomedical Network Research on Rare Diseases (CIBERER), Instituto de Salud Carlos III, Madrid, Spain.,Neuromuscular Unit, Neurology Department, Sant Joan de Déu Research Institute, Sant Joan de Déu Hospital, Barcelona, Spain
| | - M Dolores Sardina
- Pediatric Neurology Department, Badajoz Hospital Complex, Badajoz, Spain
| | - Concepcion Álvarez Del Vayo
- Center for Biomedical Network Research on Neurodegenerative Diseases, Instituto de Salud Carlos III, Madrid, Spain.,Pharmacy Department, Virgin of el Rocío University Hospital, Seville, Spain
| | - Olga Serrano
- Pharmacy Department, October 12 Hospital, Madrid, Spain
| | - Yuelin Long
- Department of Biostatistics, Mailman School of Public Health, Columbia University Medical Center, New York, NY
| | - Yuqi Tu
- Department of Biostatistics, Mailman School of Public Health, Columbia University Medical Center, New York, NY
| | - Bruce Levin
- Department of Biostatistics, Mailman School of Public Health, Columbia University Medical Center, New York, NY
| | - John L P Thompson
- Department of Biostatistics, Mailman School of Public Health, Columbia University Medical Center, New York, NY
| | - Kristen Engelstad
- Neurology Department, H. Houston Merritt Center, Columbia University Medical Center, New York, NY
| | - Jasim Uddin
- Neurology Department, H. Houston Merritt Center, Columbia University Medical Center, New York, NY
| | - Javier Torres-Torronteras
- Center for Biomedical Network Research on Rare Diseases (CIBERER), Instituto de Salud Carlos III, Madrid, Spain.,Research Group on Neuromuscular and Mitochondrial Diseases, Vall d'Hebron Research Institute, Autonomous University of Barcelona, Barcelona, Spain
| | - Cecilia Jimenez-Mallebrera
- Center for Biomedical Network Research on Rare Diseases (CIBERER), Instituto de Salud Carlos III, Madrid, Spain.,Neuromuscular Unit, Neurology Department, Sant Joan de Déu Research Institute, Sant Joan de Déu Hospital, Barcelona, Spain
| | - Ramon Martí
- Center for Biomedical Network Research on Rare Diseases (CIBERER), Instituto de Salud Carlos III, Madrid, Spain.,Research Group on Neuromuscular and Mitochondrial Diseases, Vall d'Hebron Research Institute, Autonomous University of Barcelona, Barcelona, Spain
| | - Carmen Paradas
- Neuromuscular Disorders Unit, Neurology Department, Instituto de Biomedicina de Sevilla, Hospital U. Virgen del Rocío, Consejo Superior de Investigaciones Científicas, University of Seville, Seville, Spain.,Center for Biomedical Network Research on Neurodegenerative Diseases, Instituto de Salud Carlos III, Madrid, Spain
| | - Michio Hirano
- Neurology Department, H. Houston Merritt Center, Columbia University Medical Center, New York, NY
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3
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Wang J, Kim E, Dai H, Stefans V, Vogel H, Al Jasmi F, Schrier Vergano SA, Castro D, Bernes S, Bhambhani V, Long C, El-Hattab AW, Wong LJ. Clinical and molecular spectrum of thymidine kinase 2-related mtDNA maintenance defect. Mol Genet Metab 2018; 124:124-130. [PMID: 29735374 DOI: 10.1016/j.ymgme.2018.04.012] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Revised: 04/25/2018] [Accepted: 04/26/2018] [Indexed: 11/29/2022]
Abstract
Mitochondrial DNA maintenance (mtDNA) defects have a wide range of causes, each with a set of phenotypes that overlap with many other neurological or muscular diseases. Clinicians face the challenge of narrowing down a long list of differential diagnosis when encountered with non-specific neuromuscular symptoms. Biallelic pathogenic variants in the Thymidine Kinase 2 (TK2) gene cause a myopathic form of mitochondrial DNA maintenance defect. Since the first description in 2001, there have been 71 patients reported with 42 unique pathogenic variants. Here we are reporting 11 new cases with 5 novel pathogenic variants. We describe and analyze a total of 82 cases with 47 unique TK2 pathogenic variants in effort to formulate a comprehensive molecular and clinical spectrum of TK2-related mtDNA maintenance disorders.
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Affiliation(s)
- Julia Wang
- Medical Scientist Training Program, Program in Developmental Biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, United States.
| | - Emily Kim
- Department of BioSciences, Rice University, 6100 Main Street, Houston, TX 77005, United States
| | - Honzheng Dai
- Department of Human and Molecular Genetics, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, United States
| | - Vikki Stefans
- UAMS College of Medicine, Arkansas Children's Hospital, 1 Children's Way, Little Rock, AR 72202, United States
| | - Hannes Vogel
- Pathology, Stanford University School of Medicine, R241 Edwards Building, 300 Pasteur Drive, Palo Alto, CA 94305, United States
| | - Fatma Al Jasmi
- Division of Clinical Genetics and Metabolic Disorders, Pediatrics Department, Tawam Hospital, Al-Ain, United Arab Emirates
| | - Samantha A Schrier Vergano
- Division of Medical Genetics and Metabolism, Children's Hospital of The King's Daughters, 601 Children's Lane, Norfolk, VA 23507, United States
| | - Diana Castro
- Department of Pediatric, Neurology and Neurotherapeutics, Children's Health Dallas, University of Texas Southwestern, 2350 N Stemmons Freeway, Dallas, TX 75207, United States
| | - Saunder Bernes
- Department of Neurology, Phoenix Children's Hospital, Barrows Neurological Institute, 1919 East Thomas Road, Phoenix, AZ 85016, United States
| | - Vikas Bhambhani
- Genomics Medicine Program, Children's Hospital Minnesota, 2525 Chicago Ave S, Minneapolis, MN 55404, United States
| | - Catherine Long
- Genomics Medicine Program, Children's Hospital Minnesota, 2525 Chicago Ave S, Minneapolis, MN 55404, United States
| | - Ayman W El-Hattab
- Division of Clinical Genetics and Metabolic Disorders, Pediatrics Department, Tawam Hospital, Al-Ain, United Arab Emirates
| | - Lee-Jun Wong
- Department of Human and Molecular Genetics, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, United States.
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4
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Garone C, Taylor RW, Nascimento A, Poulton J, Fratter C, Domínguez-González C, Evans JC, Loos M, Isohanni P, Suomalainen A, Ram D, Hughes MI, McFarland R, Barca E, Lopez Gomez C, Jayawant S, Thomas ND, Manzur AY, Kleinsteuber K, Martin MA, Kerr T, Gorman GS, Sommerville EW, Chinnery PF, Hofer M, Karch C, Ralph J, Cámara Y, Madruga-Garrido M, Domínguez-Carral J, Ortez C, Emperador S, Montoya J, Chakrapani A, Kriger JF, Schoenaker R, Levin B, Thompson JLP, Long Y, Rahman S, Donati MA, DiMauro S, Hirano M. Retrospective natural history of thymidine kinase 2 deficiency. J Med Genet 2018; 55:515-521. [PMID: 29602790 PMCID: PMC6073909 DOI: 10.1136/jmedgenet-2017-105012] [Citation(s) in RCA: 64] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Revised: 03/02/2018] [Accepted: 03/11/2018] [Indexed: 12/21/2022]
Abstract
Background Thymine kinase 2 (TK2) is a mitochondrial matrix protein encoded in nuclear DNA and phosphorylates the pyrimidine nucleosides: thymidine and deoxycytidine. Autosomal recessive TK2 mutations cause a spectrum of disease from infantile onset to adult onset manifesting primarily as myopathy. Objective To perform a retrospective natural history study of a large cohort of patients with TK2 deficiency. Methods The study was conducted by 42 investigators across 31 academic medical centres. Results We identified 92 patients with genetically confirmed diagnoses of TK2 deficiency: 67 from literature review and 25 unreported cases. Based on clinical and molecular genetics findings, we recognised three phenotypes with divergent survival: (1) infantile-onset myopathy (42.4%) with severe mitochondrial DNA (mtDNA) depletion, frequent neurological involvement and rapid progression to early mortality (median post-onset survival (POS) 1.00, CI 0.58 to 2.33 years); (2) childhood-onset myopathy (40.2%) with mtDNA depletion, moderate-to-severe progression of generalised weakness and median POS at least 13 years; and (3) late-onset myopathy (17.4%) with mild limb weakness at onset and slow progression to respiratory insufficiency with median POS of 23 years. Ophthalmoparesis and facial weakness are frequent in adults. Muscle biopsies show multiple mtDNA deletions often with mtDNA depletion. Conclusions In TK2 deficiency, age at onset, rate of weakness progression and POS are important variables that define three clinical subtypes. Nervous system involvement often complicates the clinical course of the infantile-onset form while extraocular muscle and facial involvement are characteristic of the late-onset form. Our observations provide essential information for planning future clinical trials in this disorder.
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Affiliation(s)
- Caterina Garone
- Department of Neurology, Columbia University Medical Center, New York City, New York, USA.,MRC Mitochondrial Biology Unit, Cambridge Biomedical Campus, Cambridge, UK
| | - Robert W Taylor
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Newcastle upon Tyne, UK
| | - Andrés Nascimento
- Neuromuscular Unit, Hospital Universitario 12 de Octubre, Madrid, Spain
| | - Joanna Poulton
- Nuffield Department of Obstetrics and Gynaecology, University of Oxford, Oxford, UK
| | - Carl Fratter
- Oxford Medical Genetics Laboratories, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - Cristina Domínguez-González
- Neuromuscular Unit, Hospital Universitario 12 de Octubre, Madrid, Spain.,Centre for Biomedical Network Research on Rare Diseases (CIBERER), Instituto de Salud Carlos III, Madrid, Spain.,Instituto de Investigación, Hospital Universitario 12 de Octubre, Madrid, Spain
| | - Julie C Evans
- Oxford Medical Genetics Laboratories, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - Mariana Loos
- Neurology Department, Hospital de Pediatría 'Prof. Dr JP Garrahan', Buenos Aires, Argentina
| | - Pirjo Isohanni
- Research Programs Unit, Molecular Neurology, Biomedicum Helsinki, University of Helsinki, Helsinki, Finland.,Department of Child Neurology, Children's Hospital, University of Helsinki, Helsinki University Hospital, Helsinki, Finland
| | - Anu Suomalainen
- Research Programs Unit, Molecular Neurology, Biomedicum Helsinki, University of Helsinki, Helsinki, Finland.,Neuroscience Center, University of Helsinki, Helsinki, Finland.,Department of Neurology, Helsinki University Hospital, Helsinki, Finland
| | - Dipak Ram
- Department of Paediatric Neurology, Royal Manchester Children's Hospital, Manchester, UK
| | - M Imelda Hughes
- Department of Paediatric Neurology, Royal Manchester Children's Hospital, Manchester, UK
| | - Robert McFarland
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Newcastle upon Tyne, UK
| | - Emanuele Barca
- Department of Neurology, Columbia University Medical Center, New York City, New York, USA.,UOC Neurology and Neuromuscular Diseases, Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy
| | - Carlos Lopez Gomez
- Department of Neurology, Columbia University Medical Center, New York City, New York, USA
| | - Sandeep Jayawant
- Paediatric Neurology, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - Neil D Thomas
- Paediatric Neurology, University Hospital Southampton NHS Foundation Trust, Southampton, UK
| | - Adnan Y Manzur
- Dubowitz Neuromuscular Centre, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
| | - Karin Kleinsteuber
- Pediatric Neurology, Faculty of Medicine, Universidad de Chile, Clínica Las Condes, Santiago, Chile
| | - Miguel A Martin
- Centre for Biomedical Network Research on Rare Diseases (CIBERER), Instituto de Salud Carlos III, Madrid, Spain.,Instituto de Investigación, Hospital Universitario 12 de Octubre, Madrid, Spain
| | - Timothy Kerr
- Paediatric Neurology, St George's University Hospitals NHS Foundation Trust, London, UK
| | - Grainne S Gorman
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Newcastle upon Tyne, UK
| | - Ewen W Sommerville
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Newcastle upon Tyne, UK
| | - Patrick F Chinnery
- MRC Mitochondrial Biology Unit, Cambridge Biomedical Campus, Cambridge, UK.,Wellcome Trust Centre for Mitochondrial Research, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK
| | - Monika Hofer
- Department of Neuropathology, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - Christoph Karch
- Department of Neurology, University of California San Francisco, San Francisco, California, USA
| | - Jeffrey Ralph
- Department of Neurology, University of California San Francisco, San Francisco, California, USA
| | - Yolanda Cámara
- Research Group on Neuromuscular and Mitochondrial Disorders, Vall d'Hebron Institut de Recerca, Barcelona, Spain.,Centre for Biomedical Network Research on Rare Diseases (CIBERER), Instituto de Salud Carlos III, Barcelona, Spain
| | - Marcos Madruga-Garrido
- Sección de Neuropediatría, Hospital Universitario Virgen del Rocío, Instituto de Biomedicina de Sevilla, Seville, Spain
| | - Jana Domínguez-Carral
- Neuromuscular Unit, Department of Neurology, Hospital Sant Joan de Déu, CIBERER, ISCIII, Universitat de Barcelona, Barcelona, Spain
| | - Carlos Ortez
- Neuromuscular Unit, Hospital Universitario 12 de Octubre, Madrid, Spain
| | - Sonia Emperador
- Department of Biochemistry and Molecular Biology, University of Zaragoza-CIBERER-Instituto de investigaciones Sanitarias de Aragón, Zaragoza, Spain
| | - Julio Montoya
- Department of Biochemistry and Molecular Biology, University of Zaragoza-CIBERER-Instituto de investigaciones Sanitarias de Aragón, Zaragoza, Spain
| | - Anupam Chakrapani
- Metabolic Unit, Great Ormond Street Hospital NHS Foundation Trust, London, UK
| | - Joshua F Kriger
- Department of Biostatistics, Mailman School of Public Health, Columbia University Medical Center, New York City, New York, USA
| | - Robert Schoenaker
- Department of Neurology, Columbia University Medical Center, New York City, New York, USA
| | - Bruce Levin
- Department of Biostatistics, Mailman School of Public Health, Columbia University Medical Center, New York City, New York, USA
| | - John L P Thompson
- Department of Biostatistics, Mailman School of Public Health, Columbia University Medical Center, New York City, New York, USA
| | - Yuelin Long
- Department of Biostatistics, Mailman School of Public Health, Columbia University Medical Center, New York City, New York, USA
| | - Shamima Rahman
- Metabolic Unit, Great Ormond Street Hospital NHS Foundation Trust, London, UK.,Mitochondrial Research Group, Genetics and Genomic Medicine, UCL Great Ormond Street Institute of Child Health, London, UK
| | | | - Salvatore DiMauro
- Department of Neurology, Columbia University Medical Center, New York City, New York, USA
| | - Michio Hirano
- Department of Neurology, Columbia University Medical Center, New York City, New York, USA
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5
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Sun R, Wang L. Thymidine Kinase 2 Enzyme Kinetics Elucidate the Mechanism of Thymidine-Induced Mitochondrial DNA Depletion. Biochemistry 2014; 53:6142-50. [DOI: 10.1021/bi5006877] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Ren Sun
- Department
of Anatomy, Physiology
and Biochemistry, Swedish University of Agricultural Sciences, Box 7011, SE-750 07 Uppsala, Sweden
| | - Liya Wang
- Department
of Anatomy, Physiology
and Biochemistry, Swedish University of Agricultural Sciences, Box 7011, SE-750 07 Uppsala, Sweden
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6
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Roos S, Lindgren U, Ehrstedt C, Moslemi A, Oldfors A. Mitochondrial DNA depletion in single fibers in a patient with novel TK2 mutations. Neuromuscul Disord 2014; 24:713-20. [DOI: 10.1016/j.nmd.2014.05.009] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2014] [Revised: 05/09/2014] [Accepted: 05/20/2014] [Indexed: 11/30/2022]
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Chanprasert S, Wang J, Weng SW, Enns GM, Boué DR, Wong BL, Mendell JR, Perry DA, Sahenk Z, Craigen WJ, Alcala FJC, Pascual JM, Melancon S, Zhang VW, Scaglia F, Wong LJC. Molecular and clinical characterization of the myopathic form of mitochondrial DNA depletion syndrome caused by mutations in the thymidine kinase (TK2) gene. Mol Genet Metab 2013; 110:153-61. [PMID: 23932787 DOI: 10.1016/j.ymgme.2013.07.009] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/03/2013] [Revised: 07/10/2013] [Accepted: 07/10/2013] [Indexed: 11/26/2022]
Abstract
Mitochondrial DNA (mtDNA) depletion syndromes (MDSs) are a clinically and molecularly heterogeneous group of mitochondrial cytopathies characterized by severe mtDNA copy number reduction in affected tissues. Clinically, MDSs are mainly categorized as myopathic, encephalomyopathic, hepatocerebral, or multi-systemic forms. To date, the myopathic form of MDS is mainly caused by mutations in the TK2 gene, which encodes thymidine kinase 2, the first and rate limiting step enzyme in the phosphorylation of pyrimidine nucleosides. We analyzed 9 unrelated families with 11 affected subjects exhibiting the myopathic form of MDS, by sequencing the TK2 gene. Twelve mutations including 4 novel mutations were detected in 9 families. Skeletal muscle specimens were available from 7 out of 11 subjects. Respiratory chain enzymatic activities in skeletal muscle were measured in 6 subjects, and enzymatic activities were reduced in 3 subjects. Quantitative analysis of mtDNA content in skeletal muscle was performed in 5 subjects, and marked mtDNA content reduction was observed in each. In addition, we outline the molecular and clinical characteristics of this syndrome in a total of 52 patients including those previously reported, and a total of 36 TK2 mutations are summarized. Clinically, hypotonia and proximal muscle weakness are the major phenotypes present in all subjects. In summary, our study expands the molecular and clinical spectrum associated with TK2 deficiency.
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Affiliation(s)
- Sirisak Chanprasert
- Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
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8
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Tyynismaa H, Sun R, Ahola-Erkkilä S, Almusa H, Pöyhönen R, Korpela M, Honkaniemi J, Isohanni P, Paetau A, Wang L, Suomalainen A. Thymidine kinase 2 mutations in autosomal recessive progressive external ophthalmoplegia with multiple mitochondrial DNA deletions. Hum Mol Genet 2011; 21:66-75. [PMID: 21937588 DOI: 10.1093/hmg/ddr438] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Autosomal-inherited progressive external ophthalmoplegia (PEO) is an adult-onset disease characterized by the accumulation of multiple mitochondrial DNA (mtDNA) deletions in post-mitotic tissues. Mutations in six different genes have been described to cause the autosomal dominant form of the disease, but only mutations in the DNA polymerase gamma gene are known to cause autosomal recessive PEO (arPEO), leaving the genetic background of arPEO mostly unknown. Here we used whole-exome sequencing and identified compound heterozygous mutations, leading to two amino acid alterations R225W and a novel T230A in thymidine kinase 2 (TK2) in arPEO patients. TK2 is an enzyme of the mitochondrial nucleotide salvage pathway and its loss-of-function mutations have previously been shown to underlie the early-infantile myopathic form of mtDNA depletion syndrome (MDS). Our TK2 activity measurements of patient fibroblasts and mutant recombinant proteins show that the combination of the identified arPEO variants, R225W and T230A, leads to a significant reduction in TK2 activity, consistent with the late-onset phenotype, whereas homozygosity for R225W, previously associated with MDS, leads to near-total loss of activity. Our finding identifies a new genetic cause of arPEO with multiple mtDNA deletions. Furthermore, MDS and multiple mtDNA deletion disorders are manifestations of the same pathogenic pathways affecting mtDNA replication and repair, indicating that MDS-associated genes should be studied when searching for genetic background of PEO disorders.
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Affiliation(s)
- Henna Tyynismaa
- Research Programs Unit, Molecular Neurology, Biomedicum Helsinki, Haartmaninkatu 8, Helsinki 00290, Finland.
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9
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Martí R, Nascimento A, Colomer J, Lara MC, López-Gallardo E, Ruiz-Pesini E, Montoya J, Andreu AL, Briones P, Pineda M. Hearing loss in a patient with the myopathic form of mitochondrial DNA depletion syndrome and a novel mutation in the TK2 gene. Pediatr Res 2010; 68:151-4. [PMID: 20421844 DOI: 10.1203/pdr.0b013e3181e33bbe] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Mitochondrial DNA (mtDNA) depletion syndrome (MDS) is a devastating disorder of infancy caused by a significant reduction of the number of copies of mitochondrial DNA in one or more tissues. We report a Spanish patient with the myopathic form of MDS, harboring two mutations in the thymidine kinase 2 gene (TK2): a previously reported deletion (p.K244del) and a novel nucleotide duplication in the exon 2, generating a frameshift and premature stop codon. Sensorineural hearing loss was a predominant symptom in the patient and a novel feature of MDS due to TK2 mutations. The patient survived up to the age of 8.5 y, which confirms that survival above the age of 5 y is not infrequent in patients with MDS due to TK2 deficiency.
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Affiliation(s)
- Ramon Martí
- Laboratory of Mitochondrial Disorders, Institut de Recerca Hospital Universitari Vall d'Hebron, 08035 Barcelona, Spain
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10
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Collated mutations in mitochondrial DNA (mtDNA) depletion syndrome (excluding the mitochondrial gamma polymerase, POLG1). Biochim Biophys Acta Mol Basis Dis 2009; 1792:1109-12. [DOI: 10.1016/j.bbadis.2009.08.016] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2009] [Accepted: 08/27/2009] [Indexed: 01/09/2023]
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11
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Walter JH. Genes, patients, families, doctors-mutation analysis in clinical practice. J Inherit Metab Dis 2009; 32:441-6. [PMID: 19306072 DOI: 10.1007/s10545-009-1085-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/27/2008] [Revised: 02/04/2009] [Accepted: 02/13/2009] [Indexed: 10/21/2022]
Abstract
Developments in mutation analysis have led to significant benefits for patients with inherited metabolic disorders and their families. This is particularly the case where new methodologies have prevented the need for invasive tissue biopsies or have allowed carrier detection or first trimester prenatal testing to be undertaken. Whereas in the past it may have only been possible to identify specific 'common' mutations, the availability of techniques, such as automated sequencing, and novel technologies including mutation scanning techniques, multiplex ligation dependent probe amplification, and array technologies, have vastly improved the diagnostic efficiency of molecular testing.
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Affiliation(s)
- J H Walter
- Inherited Metabolic Disease, Willink Biochemical Genetics Unit, Royal Manchester Children's Hospital, Manchester M27 4HA, UK
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12
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Kollberg G, Darin N, Benan K, Moslemi AR, Lindal S, Tulinius M, Oldfors A, Holme E. A novel homozygous RRM2B missense mutation in association with severe mtDNA depletion. Neuromuscul Disord 2009; 19:147-50. [PMID: 19138848 DOI: 10.1016/j.nmd.2008.11.014] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2008] [Revised: 10/24/2008] [Accepted: 11/03/2008] [Indexed: 10/21/2022]
Abstract
This report describes two brothers, both deceased in infancy, with severe depletion of mitochondrial DNA (mtDNA) in muscle tissue. Both had feeding difficulties, failure to thrive, severe muscular hypotonia and lactic acidosis. One of the boys developed a renal proximal tubulopathy. A novel homozygous c.686 G-->T missense mutation in the RRM2B gene, encoding the p53-inducible ribonucleotide reductase subunit (p53R2), was identified. This is the third report on mutations in RRM2B associated with severe mtDNA depletion, which further highlights the importance of de novo synthesis of deoxyribonucleotides (dNTPs) for mtDNA maintenance.
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Affiliation(s)
- Gittan Kollberg
- Department of Clinical Chemistry, Sahlgrenska University Hospital, Bruna Stråket 16, SE-413 45 Göteborg, Sweden.
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13
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Pérez-Pérez MJ, Priego EM, Hernández AI, Familiar O, Camarasa MJ, Negri A, Gago F, Balzarini J. Structure, physiological role, and specific inhibitors of human thymidine kinase 2 (TK2): present and future. Med Res Rev 2008; 28:797-820. [PMID: 18459168 PMCID: PMC7168489 DOI: 10.1002/med.20124] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Abstract
Human mitochondrial thymidine kinase (TK2) is a pyrimidine deoxynucleoside kinase (dNK) that catalyzes the phosphorylation of pyrimidine deoxynucleosides to their corresponding deoxynucleoside 5′‐monophosphates by γ‐phosphoryl transfer from ATP. In resting cells, TK2 is suggested to play a key role in the mitochondrial salvage pathway to provide pyrimidine nucleotides for mitochondrial DNA (mtDNA) synthesis and maintenance. However, recently the physiological role of TK2turned out to have direct clinical relevance as well. Point mutations in the gene encoding TK2 have been correlated to mtDNA disorders in a heterogeneous group of patients suffering from the so‐called mtDNA depletion syndrome (MDS). TK2 activity could also be involved in mitochondrial toxicity associated to prolonged treatment with antiviral nucleoside analogues like AZT and FIAU. Therefore, TK2 inhibitors can be considered as valuable tools to unravel the role of TK2 in the maintenance and homeostasis of mitochondrial nucleotide pools and mtDNA, and to clarify the contribution of TK2 activity to mitochondrial toxicity of certain antivirals. Highly selective TK‐2 inhibitors having an acyclic nucleoside structure and efficiently discriminating between TK‐2 and the closely related TK‐1 have already been reported. It is actually unclear whether these agents efficiently reach the inner mitochondrial compartment. In the present review article,structural features of TK2, MDS‐related mutations observed in TK2 and their role in MDS will be discussed. Also, an update on novel and selective TK2 inhibitors will be provided. © 2008 Wiley Periodicals, Inc. Med Res Rev, 28, No. 5, 797–820, 2008
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Götz A, Isohanni P, Pihko H, Paetau A, Herva R, Saarenpää-Heikkilä O, Valanne L, Marjavaara S, Suomalainen A. Thymidine kinase 2 defects can cause multi-tissue mtDNA depletion syndrome. Brain 2008; 131:2841-50. [PMID: 18819985 DOI: 10.1093/brain/awn236] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Mitochondrial DNA depletion syndrome (MDS) is a severe recessively inherited disease of childhood. It manifests most often in infancy, is rapidly progressive and leads to early death. MDS is caused by an increasing number of nuclear genes leading to multisystemic or tissue-specific decrease in mitochondrial DNA (mtDNA) copy number. Thymidine kinase 2 (TK2) has been reported to cause a myopathic form of MDS. We report here the clinical, autopsy and molecular genetic findings of rapidly progressive fatal infantile mitochondrial syndrome. All of our seven patients had rapidly progressive myopathy/encephalomyopathy, leading to respiratory failure within the first 3 years of life, with high creatine kinase values and dystrophic changes in the muscle with cytochrome c oxidase-negative fibres. In addition, two patients also had terminal-phase seizures, one had epilepsia partialis continua and one had cortical laminar necrosis. We identified two different homozygous or compound heterozygous mutations in the TK2 gene in all the patients: c.739 C s -> T and c.898 C -> T, leading to p.R172W and p.R225W changes at conserved protein sites. R172W mutation led to myopathy or encephalomyopathy with the onset during the first months of life, and was associated with severe mtDNA depletion in the muscle, brain and liver. Homozygosity for R225W mutation manifested during the second year of life as a myopathy, and showed muscle-specific mtDNA depletion. Both mutations originated from single ancient founders, with Finnish origin and enrichment for the new R172W mutation, and possibly Scandinavian ancestral origin for the R225W. We conclude that TK2 mutations may manifest as infantile-onset fatal myopathy with dystrophic features, but should be considered also in infantile progressive encephalomyopathy with wide-spread mtDNA depletion.
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Affiliation(s)
- Alexandra Götz
- Research Programme of Molecular Neurology, Biomedicum-Helsinki, University of Helsinki, Helsinki, Finland
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15
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Leshinsky-Silver E, Michelson M, Cohen S, Ginsberg M, Sadeh M, Barash V, Lerman-Sagie T, Lev D. A defect in the thymidine kinase 2 gene causing isolated mitochondrial myopathy without mtDNA depletion. Eur J Paediatr Neurol 2008; 12:309-13. [PMID: 17951082 DOI: 10.1016/j.ejpn.2007.09.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/23/2007] [Revised: 08/28/2007] [Accepted: 09/02/2007] [Indexed: 11/24/2022]
Abstract
Isolated mitochondrial myopathies (IMM) are either due to primary defects in mtDNA, in nuclear genes that control mtDNA abundance and structure such as thymidine kinase 2 (TK2), or due to CoQ deficiency. Defects in the TK2 gene have been found to be associated with mtDNA depletion attributed to a depleted mitochondrial dNTP pool in non-dividing cells. We report an unusual case of IMM, homozygous for the H90N mutation in the TK2 gene but unlike other cases with the same mutation, does not demonstrate mtDNA depletion. The patient's clinical course is relatively mild and a muscle biopsy showed ragged red muscle fibers with a mild decrease in complexes I and an increase in complexes IV and II activities. This report extends the phenotypic expression of TK2 defects and suggests that all patients who present with an IMM even with normal quantities of mtDNA should be screened for TK2 mutations.
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16
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Xu Y, Johansson M, Karlsson A. Human UMP-CMP kinase 2, a novel nucleoside monophosphate kinase localized in mitochondria. J Biol Chem 2007; 283:1563-1571. [PMID: 17999954 DOI: 10.1074/jbc.m707997200] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Enzyme deficiency in the salvage pathway of deoxyribonucleotide synthesis in mitochondria can cause mtDNA depletion syndromes. We have identified a human mitochondrial UMP-CMP kinase (UMP-CMPK, cytidylate kinase; EC 2.7.4.14), designated as UMP-CMP kinase 2 (UMP-CMPK2). The C-terminal domain of this 449-amino acid protein contains all consensus motifs of a nucleoside monophosphate kinase. Phylogenetic analysis showed that UMP-CMPK2 belonged to a novel nucleoside monophosphate kinase family, which was closer to thymidylate kinase than to cytosolic UMP-CMP kinase. Subcellular localization with green fluorescent protein fusion proteins illustrated that UMP-CMPK2 was localized in the mitochondria of HeLa cells and that the mitochondrial targeting signal was included in the N-terminal 22 amino acids. The enzyme was able to phosphorylate dUMP, dCMP, CMP, and UMP with ATP as phosphate donor, but the kinetic properties were different compared with the cytosolic UMP-CMPK. Its efficacy to convert dUMP was highest, followed by dCMP, whereas CMP and UMP were the poorest substrates. It also phosphorylated the monophosphate forms of the nucleoside analogs ddC, dFdC, araC, BVDU, and FdUrd, which suggests that UMP-CMPK2 may be involved in mtDNA depletion caused by long term treatment with ddC or other pyrimidine analogs. UMP-CMPK2 mRNA expression was exclusively detected in chronic myelogenous leukemia K-562 and lymphoblastic leukemia MOLT-4 among eight studied cancer cell lines. Particular high expression in leukemia cells, dominant expression in bone marrow, and tight correlation with macrophage activation and inflammatory response suggest that UMP-CMPK2 may have other functions in addition to the supply of substrates for mtDNA synthesis.
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Affiliation(s)
- Yunjian Xu
- Department of Laboratory Medicine, Karolinska Institute, Stockholm 14186, Sweden.
| | - Magnus Johansson
- Department of Laboratory Medicine, Karolinska Institute, Stockholm 14186, Sweden
| | - Anna Karlsson
- Department of Laboratory Medicine, Karolinska Institute, Stockholm 14186, Sweden
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17
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Oldfors A, Tulinius M. Mitochondrial encephalomyopathies. HANDBOOK OF CLINICAL NEUROLOGY 2007; 86:125-165. [PMID: 18808998 DOI: 10.1016/s0072-9752(07)86006-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
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18
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Galbiati S, Bordoni A, Papadimitriou D, Toscano A, Rodolico C, Katsarou E, Sciacco M, Garufi A, Prelle A, Aguennouz M', Bonsignore M, Crimi M, Martinuzzi A, Bresolin N, Papadimitriou A, Comi GP. New mutations in TK2 gene associated with mitochondrial DNA depletion. Pediatr Neurol 2006; 34:177-85. [PMID: 16504786 DOI: 10.1016/j.pediatrneurol.2005.07.013] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/12/2005] [Revised: 06/14/2005] [Accepted: 07/11/2005] [Indexed: 11/17/2022]
Abstract
Mitochondrial deoxyribonucleic acid depletion syndromes are autosomal recessive disorders characterized by a reduction of the amount of mitochondrial deoxyribonucleic acid, which impairs the synthesis of respiratory chain complexes. Mutations in the deoxyguanosine kinase and polymerase gamma genes have been identified in hepatocerebral forms, whereas thymidine kinase 2 gene mutations have been found in patients with isolated myopathy, encephalomyopathy, or spinal muscular atrophy. Mutations in the gene encoding the beta subunit of the adenosine diphosphate-forming succinyl-coenzyme A synthetase have also been reported in a family. In this report, the clinical, molecular, morphologic, and biochemical features of five children from two independent families with an infantile encephalomyopathy are characterized. The affected children manifested muscle mitochondrial deoxyribonucleic acid depletion and three novel thymidine kinase 2 gene mutations. They consist of a homozygous substitution resulting in Ala to Val change at the highly conserved position 181 of thymidine kinase in the first family, and two heterozygous substitutions in the second family: a Cys to Trp change at residue 108 and a Leu to Pro change at residue 257 of the enzyme. Common clinical features associated with these TK2 mutations are a normal early developmental phase followed by psychomotor regression, encephalopathy often with epileptic seizures, and myopathy with features of a progressive dystrophic process.
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Affiliation(s)
- Sara Galbiati
- Centro Dino Ferrari, Department of Neurological Sciences, University of Milan, I.R.C.C.S. Ospedale Maggiore Policlinico, Milano, Italy.
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