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Mao B, Lin N, Guo D, He D, Xue H, Chen L, He Q, Zhang M, Chen M, Huang H, Xu L. Molecular analysis and prenatal diagnosis of seven Chinese families with genetic epilepsy. Front Neurosci 2023; 17:1165601. [PMID: 37250406 PMCID: PMC10213446 DOI: 10.3389/fnins.2023.1165601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Accepted: 04/13/2023] [Indexed: 05/31/2023] Open
Abstract
Introduction Genetic epilepsy is a large group of clinically and genetically heterogeneous neurological disorders characterized by recurrent seizures, which have a clear association with genetic defects. In this study, we have recruited seven families from China with neurodevelopmental abnormalities in which epilepsy was a predominant manifestation, aiming to elucidate the underlying causes and make a precise diagnosis for the cases. Methods Whole-exome sequencing (WES) combined with Sanger sequencing was used to identify the causative variants associated with the diseases in addition to essential imaging and biomedical examination. Results A gross intragenic deletion detected in MFSD8 was investigated via gap-polymerase chain reaction (PCR), real-time quantitative PCR (qPCR), and mRNA sequence analysis. We identified 11 variants in seven genes (ALDH7A1, CDKL5, PCDH19, QARS1, POLG, GRIN2A, and MFSD8) responsible for genetic epilepsy in the seven families, respectively. A total of six variants (c.1408T>G in ALDH7A1, c.1994_1997del in CDKL5, c.794G>A in QARS1, c.2453C>T in GRIN2A, and c.217dup and c.863+995_998+1480del in MFSD8) have not yet been reported to be associated with diseases and were all evaluated to be pathogenic or likely pathogenic according to the American College of Medical Genetics and Genomics (ACMG) guidelines. Methods Based on the molecular findings, we have associated the intragenic deletion in MFSD8 with the mutagenesis mechanism of Alu-mediated genomic rearrangements for the first time and provided genetic counseling, medical suggestions, and prenatal diagnosis for the families. In conclusion, molecular diagnosis is crucial to obtain improved medical outcomes and recurrence risk evaluation for genetic epilepsy.
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Affiliation(s)
- Bin Mao
- Medical Genetic Diagnosis and Therapy Center, Fujian Maternity and Child Health Hospital, College of Clinical Medicine for Obstetrics and Gynecology and Pediatrics, Fujian Medical University, Fuzhou, China
- Fujian Provincial Key Laboratory of Prenatal Diagnosis and Birth Defect, Fuzhou, China
| | - Na Lin
- Medical Genetic Diagnosis and Therapy Center, Fujian Maternity and Child Health Hospital, College of Clinical Medicine for Obstetrics and Gynecology and Pediatrics, Fujian Medical University, Fuzhou, China
- Fujian Provincial Key Laboratory of Prenatal Diagnosis and Birth Defect, Fuzhou, China
| | - Danhua Guo
- Medical Genetic Diagnosis and Therapy Center, Fujian Maternity and Child Health Hospital, College of Clinical Medicine for Obstetrics and Gynecology and Pediatrics, Fujian Medical University, Fuzhou, China
- Fujian Provincial Key Laboratory of Prenatal Diagnosis and Birth Defect, Fuzhou, China
| | - Deqin He
- Medical Genetic Diagnosis and Therapy Center, Fujian Maternity and Child Health Hospital, College of Clinical Medicine for Obstetrics and Gynecology and Pediatrics, Fujian Medical University, Fuzhou, China
- Fujian Provincial Key Laboratory of Prenatal Diagnosis and Birth Defect, Fuzhou, China
| | - Huili Xue
- Medical Genetic Diagnosis and Therapy Center, Fujian Maternity and Child Health Hospital, College of Clinical Medicine for Obstetrics and Gynecology and Pediatrics, Fujian Medical University, Fuzhou, China
- Fujian Provincial Key Laboratory of Prenatal Diagnosis and Birth Defect, Fuzhou, China
| | - Lingji Chen
- Medical Genetic Diagnosis and Therapy Center, Fujian Maternity and Child Health Hospital, College of Clinical Medicine for Obstetrics and Gynecology and Pediatrics, Fujian Medical University, Fuzhou, China
- Fujian Provincial Key Laboratory of Prenatal Diagnosis and Birth Defect, Fuzhou, China
| | - Qianqian He
- Medical Genetic Diagnosis and Therapy Center, Fujian Maternity and Child Health Hospital, College of Clinical Medicine for Obstetrics and Gynecology and Pediatrics, Fujian Medical University, Fuzhou, China
- Fujian Provincial Key Laboratory of Prenatal Diagnosis and Birth Defect, Fuzhou, China
| | - Min Zhang
- Medical Genetic Diagnosis and Therapy Center, Fujian Maternity and Child Health Hospital, College of Clinical Medicine for Obstetrics and Gynecology and Pediatrics, Fujian Medical University, Fuzhou, China
- Fujian Provincial Key Laboratory of Prenatal Diagnosis and Birth Defect, Fuzhou, China
| | - Meihuan Chen
- Medical Genetic Diagnosis and Therapy Center, Fujian Maternity and Child Health Hospital, College of Clinical Medicine for Obstetrics and Gynecology and Pediatrics, Fujian Medical University, Fuzhou, China
- Fujian Provincial Key Laboratory of Prenatal Diagnosis and Birth Defect, Fuzhou, China
| | - Hailong Huang
- Medical Genetic Diagnosis and Therapy Center, Fujian Maternity and Child Health Hospital, College of Clinical Medicine for Obstetrics and Gynecology and Pediatrics, Fujian Medical University, Fuzhou, China
- Fujian Provincial Key Laboratory of Prenatal Diagnosis and Birth Defect, Fuzhou, China
| | - Liangpu Xu
- Medical Genetic Diagnosis and Therapy Center, Fujian Maternity and Child Health Hospital, College of Clinical Medicine for Obstetrics and Gynecology and Pediatrics, Fujian Medical University, Fuzhou, China
- Fujian Provincial Key Laboratory of Prenatal Diagnosis and Birth Defect, Fuzhou, China
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Li LX, Jiang LT, Pan YG, Zhang XL, Pan LZ, Nie ZY, Chen YH, Jin LJ. Clinical and Molecular Features of POLG-Related Sensory Ataxic Neuropathy with Dysarthria and Ophthalmoparesis. J Mol Neurosci 2021; 71:2462-2467. [PMID: 33791913 DOI: 10.1007/s12031-021-01831-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2020] [Accepted: 03/15/2021] [Indexed: 10/21/2022]
Abstract
Sensory ataxic neuropathy, dysarthria, and ophthalmoparesis (SANDO) is a rare mitochondrial disorder associated with mutations in the POLG gene, which encodes the DNA polymerase gamma catalytic subunit. A few POLG-related SANDO cases have been reported, but the genotype-phenotype correlation remains unclear. Here, we report a patient with SANDO carrying two novel missense variants (c.2543G>C, p.G848A and c.452 T>C, p.L151P) in POLG. We also reviewed previously reported cases to systematically evaluate the clinical and genetic features of POLG-related SANDO. A total of 35 distinct variants in the coding region of POLG were identified in 63 patients with SANDO. The most frequent variant was the p.A467T variant, followed by the p.W748S variant. The clinical spectrum of SANDO is heterogeneous. No clear correlation has been observed between the mutation types and clinical phenotypes. Our findings expand the mutational spectrum of POLG and contribute to clinical management and genetic counseling for POLG-related SANDO.
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Affiliation(s)
- Li-Xi Li
- Neurotoxin Research Center of Key Laboratory of Spine and Spinal Cord Injury Repair and Regeneration of Ministry of Education, Neurological Department of Tongji Hospital, Tongji University School of Medicine, Shanghai, China
| | - Li-Ting Jiang
- Neurotoxin Research Center of Key Laboratory of Spine and Spinal Cord Injury Repair and Regeneration of Ministry of Education, Neurological Department of Tongji Hospital, Tongji University School of Medicine, Shanghai, China
| | - You-Gui Pan
- Neurotoxin Research Center of Key Laboratory of Spine and Spinal Cord Injury Repair and Regeneration of Ministry of Education, Neurological Department of Tongji Hospital, Tongji University School of Medicine, Shanghai, China
| | - Xiao-Long Zhang
- Neurotoxin Research Center of Key Laboratory of Spine and Spinal Cord Injury Repair and Regeneration of Ministry of Education, Neurological Department of Tongji Hospital, Tongji University School of Medicine, Shanghai, China
| | - Li-Zhen Pan
- Neurotoxin Research Center of Key Laboratory of Spine and Spinal Cord Injury Repair and Regeneration of Ministry of Education, Neurological Department of Tongji Hospital, Tongji University School of Medicine, Shanghai, China
| | - Zhi-Yu Nie
- Neurotoxin Research Center of Key Laboratory of Spine and Spinal Cord Injury Repair and Regeneration of Ministry of Education, Neurological Department of Tongji Hospital, Tongji University School of Medicine, Shanghai, China
| | - Yu-Hui Chen
- Neurotoxin Research Center of Key Laboratory of Spine and Spinal Cord Injury Repair and Regeneration of Ministry of Education, Neurological Department of Tongji Hospital, Tongji University School of Medicine, Shanghai, China
| | - Ling-Jing Jin
- Neurotoxin Research Center of Key Laboratory of Spine and Spinal Cord Injury Repair and Regeneration of Ministry of Education, Neurological Department of Tongji Hospital, Tongji University School of Medicine, Shanghai, China.
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Liang KX, Vatne GH, Kristiansen CK, Ievglevskyi O, Kondratskaya E, Glover JC, Chen A, Sullivan GJ, Bindoff LA. N-acetylcysteine amide ameliorates mitochondrial dysfunction and reduces oxidative stress in hiPSC-derived dopaminergic neurons with POLG mutation. Exp Neurol 2020; 337:113536. [PMID: 33264635 DOI: 10.1016/j.expneurol.2020.113536] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Revised: 11/22/2020] [Accepted: 11/22/2020] [Indexed: 01/03/2023]
Abstract
The inability to reliably replicate mitochondrial DNA (mtDNA) by mitochondrial DNA polymerase gamma (POLG) leads to a subset of common mitochondrial diseases associated with neuronal death and depletion of neuronal mtDNA. Defining disease mechanisms in neurons remains difficult due to the limited access to human tissue. Using human induced pluripotent stem cells (hiPSCs), we generated functional dopaminergic (DA) neurons showing positive expression of dopaminergic markers TH and DAT, mature neuronal marker MAP2 and functional synaptic markers synaptophysin and PSD-95. These DA neurons were electrophysiologically characterized, and exhibited inward Na + currents, overshooting action potentials and spontaneous postsynaptic currents (sPSCs). POLG patient-specific DA neurons (POLG-DA neurons) manifested a phenotype that replicated the molecular and biochemical changes found in patient post-mortem brain samples namely loss of complex I and depletion of mtDNA. Compared to disease-free hiPSC-derived DA neurons, POLG-DA neurons exhibited loss of mitochondrial membrane potential, loss of complex I and loss of mtDNA and TFAM expression. POLG driven mitochondrial dysfunction also led to neuronal ROS overproduction and increased cellular senescence. This deficit was selectively rescued by treatment with N-acetylcysteine amide (NACA). In conclusion, our study illustrates the promise of hiPSC technology for assessing pathogenetic mechanisms associated with POLG disease, and that NACA can be a promising potential therapy for mitochondrial diseases such as those caused by POLG mutation.
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Affiliation(s)
- Kristina Xiao Liang
- Neuro-SysMed, Center of Excellence for Clinical Research in Neurological Diseases, Department of Neurology, Haukeland University Hospital, Jonas Lies vei 87, P. O. Box 7804, 5021 Bergen, Norway; Department of Clinical Medicine (K1), University of Bergen, Jonas Lies vei 87, P. O. Box 7804, 5021 Bergen, Norway.
| | - Guro Helén Vatne
- Department of Clinical Medicine (K1), University of Bergen, Jonas Lies vei 87, P. O. Box 7804, 5021 Bergen, Norway
| | - Cecilie Katrin Kristiansen
- Department of Clinical Medicine (K1), University of Bergen, Jonas Lies vei 87, P. O. Box 7804, 5021 Bergen, Norway
| | - Oleksandr Ievglevskyi
- The Intervention Centre, Oslo University Hospital, P. O. Box 4950, Nydalen, 0424 Oslo, Norway; Laboratory of Neural Development and Optical Recording (NDEVOR), Division of Physiology, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, P. O. Box 1103, Blindern, 0317 Oslo, Norway
| | - Elena Kondratskaya
- Laboratory of Neural Development and Optical Recording (NDEVOR), Division of Physiology, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, P. O. Box 1103, Blindern, 0317 Oslo, Norway
| | - Joel C Glover
- Laboratory of Neural Development and Optical Recording (NDEVOR), Division of Physiology, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, P. O. Box 1103, Blindern, 0317 Oslo, Norway; Norwegian Center for Stem Cell Research, Department of Immunology and Transfusion Medicine, Oslo University Hospital, P. O. Box 4950, Nydalen, 0424 Oslo, Norway
| | - Anbin Chen
- Department of Clinical Medicine (K1), University of Bergen, Jonas Lies vei 87, P. O. Box 7804, 5021 Bergen, Norway; Department of Neurosurgery, Qilu Hospital of Shandong University, 107 Wenhua Xi Road, Jinan 250012, Shandong Province, China; Shandong Key Laboratory of Brain Function Remodeling, Shandong University, 107 Wenhua Xi Road, Jinan 250012, Shandong Province, China
| | - Gareth John Sullivan
- Norwegian Center for Stem Cell Research, Department of Immunology and Transfusion Medicine, Oslo University Hospital, P. O. Box 4950, Nydalen, 0424 Oslo, Norway; Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, P. O. Box 1105, Blindern, 0317 Oslo, Norway; Institute of Immunology, Oslo University Hospital, PO Box 4950, 0424 Oslo, Norway; Hybrid Technology Hub - Centre of Excellence, Institute of Basic Medical Sciences, University of Oslo, P. O. Box 1110, Blindern, 0317 Oslo, Norway; Department of Pediatric Research, Oslo University Hospital, P. O. Box 4950, Nydalen, 0424 Oslo, Norway
| | - Laurence A Bindoff
- Neuro-SysMed, Center of Excellence for Clinical Research in Neurological Diseases, Department of Neurology, Haukeland University Hospital, Jonas Lies vei 87, P. O. Box 7804, 5021 Bergen, Norway; Department of Clinical Medicine (K1), University of Bergen, Jonas Lies vei 87, P. O. Box 7804, 5021 Bergen, Norway.
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4
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Ortigoza-Escobar JD. A Proposed Diagnostic Algorithm for Inborn Errors of Metabolism Presenting With Movements Disorders. Front Neurol 2020; 11:582160. [PMID: 33281718 PMCID: PMC7691570 DOI: 10.3389/fneur.2020.582160] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Accepted: 09/30/2020] [Indexed: 12/13/2022] Open
Abstract
Inherited metabolic diseases or inborn errors of metabolism frequently manifest with both hyperkinetic (dystonia, chorea, myoclonus, ataxia, tremor, etc.) and hypokinetic (rigid-akinetic syndrome) movement disorders. The diagnosis of these diseases is in many cases difficult, because the same movement disorder can be caused by several diseases. Through a literature review, two hundred and thirty one inborn errors of metabolism presenting with movement disorders have been identified. Fifty-one percent of these diseases exhibits two or more movement disorders, of which ataxia and dystonia are the most frequent. Taking into account the wide range of these disorders, a methodical evaluation system needs to be stablished. This work proposes a six-step diagnostic algorithm for the identification of inborn errors of metabolism presenting with movement disorders comprising red flags, characterization of the movement disorders phenotype (type of movement disorder, age and nature of onset, distribution and temporal pattern) and other neurological and non-neurological signs, minimal biochemical investigation to diagnose treatable diseases, radiological patterns, genetic testing and ultimately, symptomatic, and disease-specific treatment. As a strong action, it is emphasized not to miss any treatable inborn error of metabolism through the algorithm.
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Affiliation(s)
- Juan Darío Ortigoza-Escobar
- Movement Disorders Unit, Institut de Recerca Sant Joan de Déu, CIBERER-ISCIII and European Reference Network for Rare Neurological Diseases (ERN-RND), Barcelona, Spain
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5
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Abstract
Mitochondrial disorders present in a myriad of ways, which causes them to be included in the differential diagnosis for many patients with undiagnosed disease. A subset of mitochondrial disorders are caused by intrinsic defects in the mitochondrial replication machinery, leading to loss of cellular mitochondrial content over time. The diagnosis of mitochondrial disease is complex. Several best-practice guides are available that enable a higher likelihood of detecting a mitochondrial disorder. The application of genomic sequencing and advanced physiologic analysis of the electron transport chain can offer more definitive evidence of mitochondrial dysfunction.
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6
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Souza PVS, Bortholin T, Teixeira CAC, Seneor DD, Marin VDGB, Dias RB, Farias IB, Badia BML, Silva LHL, Pinto WBVR, Oliveira ASB, DiMauro S. Leigh syndrome caused by mitochondrial DNA-maintenance defects revealed by whole exome sequencing. Mitochondrion 2019; 49:25-34. [PMID: 31271879 DOI: 10.1016/j.mito.2019.06.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2018] [Revised: 11/17/2018] [Accepted: 06/24/2019] [Indexed: 01/30/2023]
Abstract
Leigh syndrome represents a complex inherited neurometabolic and neurodegenerative disorder associated with different clinical, genetic and neuroimaging findings in the context of bilateral symmetrical lesions involving the brainstem and basal ganglia. Heterogeneous neurological manifestations such as spasticity, cerebellar ataxia, dystonia, choreoathetosis and parkinsonism are associated with multisystemic and ophthalmological abnormalities due to >75 different monogenic causes. Here, we describe the clinical and genetic features of a Brazilian cohort of patients with Leigh Syndrome in which muscle biopsy analysis showed mitochondrial DNA defects and determine the utility of whole exome sequencing for a final genetic diagnostic in this cohort.
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Affiliation(s)
- P V S Souza
- Division of Neuromuscular Diseases, Department of Neurology, Department of Neurosurgery, Federal University of São Paulo (UNIFESP), São Paulo, SP, Brazil.
| | - Thiago Bortholin
- Division of Neuromuscular Diseases, Department of Neurology, Department of Neurosurgery, Federal University of São Paulo (UNIFESP), São Paulo, SP, Brazil
| | - Carlos Alberto Castro Teixeira
- Division of Neuromuscular Diseases, Department of Neurology, Department of Neurosurgery, Federal University of São Paulo (UNIFESP), São Paulo, SP, Brazil
| | - Daniel Delgado Seneor
- Division of Neuromuscular Diseases, Department of Neurology, Department of Neurosurgery, Federal University of São Paulo (UNIFESP), São Paulo, SP, Brazil
| | - Vitor Dias Gomes Barrios Marin
- Division of Neuromuscular Diseases, Department of Neurology, Department of Neurosurgery, Federal University of São Paulo (UNIFESP), São Paulo, SP, Brazil
| | - Renan Braido Dias
- Division of Neuromuscular Diseases, Department of Neurology, Department of Neurosurgery, Federal University of São Paulo (UNIFESP), São Paulo, SP, Brazil
| | - Igor Braga Farias
- Division of Neuromuscular Diseases, Department of Neurology, Department of Neurosurgery, Federal University of São Paulo (UNIFESP), São Paulo, SP, Brazil
| | - B M L Badia
- Division of Neuromuscular Diseases, Department of Neurology, Department of Neurosurgery, Federal University of São Paulo (UNIFESP), São Paulo, SP, Brazil
| | - Luiz Henrique Libardi Silva
- Division of Neuromuscular Diseases, Department of Neurology, Department of Neurosurgery, Federal University of São Paulo (UNIFESP), São Paulo, SP, Brazil
| | - W B V R Pinto
- Division of Neuromuscular Diseases, Department of Neurology, Department of Neurosurgery, Federal University of São Paulo (UNIFESP), São Paulo, SP, Brazil
| | - Acary Souza Bulle Oliveira
- Division of Neuromuscular Diseases, Department of Neurology, Department of Neurosurgery, Federal University of São Paulo (UNIFESP), São Paulo, SP, Brazil
| | - Salvatore DiMauro
- Department of Neurology, Columbia University Medical Center, New York, NY, USA
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Masingue M, Adanyeguh I, Tchikviladzé M, Maisonobe T, Jardel C, Galanaud D, Mochel F. Quantitative neuroimaging biomarkers in a series of 20 adult patients with POLG mutations. Mitochondrion 2019; 45:22-28. [DOI: 10.1016/j.mito.2018.02.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2017] [Revised: 02/11/2018] [Accepted: 02/15/2018] [Indexed: 01/12/2023]
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8
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Siibak T, Clemente P, Bratic A, Bruhn H, Kauppila TES, Macao B, Schober FA, Lesko N, Wibom R, Naess K, Nennesmo I, Wedell A, Peter B, Freyer C, Falkenberg M, Wredenberg A. A multi-systemic mitochondrial disorder due to a dominant p.Y955H disease variant in DNA polymerase gamma. Hum Mol Genet 2017; 26:2515-2525. [PMID: 28430993 PMCID: PMC5886115 DOI: 10.1093/hmg/ddx146] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2017] [Accepted: 04/11/2017] [Indexed: 12/28/2022] Open
Abstract
Mutations in the mitochondrial DNA polymerase, POLG, are associated with a variety of clinical presentations, ranging from early onset fatal brain disease in Alpers syndrome to chronic progressive external ophthalmoplegia. The majority of mutations are linked with disturbances of mitochondrial DNA (mtDNA) integrity and maintenance. On a molecular level, depending on their location within the enzyme, mutations either lead to mtDNA depletion or the accumulation of multiple mtDNA deletions, and in some cases these molecular changes can be correlated to the clinical presentation. We identified a patient with a dominant p.Y955H mutation in POLG, presenting with a severe, early-onset multi-systemic mitochondrial disease with bilateral sensorineural hearing loss, cataract, myopathy, and liver failure. Using a combination of disease models of Drosophila melanogaster and in vitro biochemistry analysis, we compare the molecular consequences of the p.Y955H mutation to the well-documented p.Y955C mutation. We demonstrate that both mutations affect mtDNA replication and display a dominant negative effect, with the p.Y955H allele resulting in a more severe polymerase dysfunction.
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Affiliation(s)
- Triinu Siibak
- Department of Medical Biochemistry and Cell Biology, Institute of Biomedicine, University of Gothenburg, Gothenburg SE-405?30, Sweden
| | - Paula Clemente
- Max Planck Institute Biology of Ageing - Karolinska Institutet Laboratory, Division of Metabolic Diseases, Department of Laboratory Medicine, Karolinska Institutet, Stockholm, SE-171 77, Sweden.,Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm SE-171 77, Sweden
| | - Ana Bratic
- Department of Mitochondrial Biology, Max Planck Institute for Biology of Ageing, Cologne D-50931, Germany
| | - Helene Bruhn
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm SE-171 77, Sweden.,Centre for Inherited Metabolic Diseases, Karolinska University Hospital, Stockholm SE-171 76, Sweden
| | - Timo E S Kauppila
- Department of Mitochondrial Biology, Max Planck Institute for Biology of Ageing, Cologne D-50931, Germany
| | - Bertil Macao
- Department of Medical Biochemistry and Cell Biology, Institute of Biomedicine, University of Gothenburg, Gothenburg SE-405?30, Sweden
| | - Florian A Schober
- Max Planck Institute Biology of Ageing - Karolinska Institutet Laboratory, Division of Metabolic Diseases, Department of Laboratory Medicine, Karolinska Institutet, Stockholm, SE-171 77, Sweden.,Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm SE-171 77, Sweden
| | - Nicole Lesko
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm SE-171 77, Sweden.,Centre for Inherited Metabolic Diseases, Karolinska University Hospital, Stockholm SE-171 76, Sweden
| | - Rolf Wibom
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm SE-171 77, Sweden.,Centre for Inherited Metabolic Diseases, Karolinska University Hospital, Stockholm SE-171 76, Sweden
| | - Karin Naess
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm SE-171 77, Sweden.,Centre for Inherited Metabolic Diseases, Karolinska University Hospital, Stockholm SE-171 76, Sweden
| | - Inger Nennesmo
- Department of Pathology, Karolinska University Hospital, SE-171?77 Stockholm, Sweden
| | - Anna Wedell
- Max Planck Institute Biology of Ageing - Karolinska Institutet Laboratory, Division of Metabolic Diseases, Department of Laboratory Medicine, Karolinska Institutet, Stockholm, SE-171 77, Sweden.,Centre for Inherited Metabolic Diseases, Karolinska University Hospital, Stockholm SE-171 76, Sweden.,Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm SE-171 76, Sweden
| | - Bradley Peter
- Department of Medical Biochemistry and Cell Biology, Institute of Biomedicine, University of Gothenburg, Gothenburg SE-405?30, Sweden
| | - Christoph Freyer
- Max Planck Institute Biology of Ageing - Karolinska Institutet Laboratory, Division of Metabolic Diseases, Department of Laboratory Medicine, Karolinska Institutet, Stockholm, SE-171 77, Sweden.,Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm SE-171 77, Sweden.,Centre for Inherited Metabolic Diseases, Karolinska University Hospital, Stockholm SE-171 76, Sweden
| | - Maria Falkenberg
- Department of Medical Biochemistry and Cell Biology, Institute of Biomedicine, University of Gothenburg, Gothenburg SE-405?30, Sweden
| | - Anna Wredenberg
- Max Planck Institute Biology of Ageing - Karolinska Institutet Laboratory, Division of Metabolic Diseases, Department of Laboratory Medicine, Karolinska Institutet, Stockholm, SE-171 77, Sweden.,Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm SE-171 77, Sweden.,Centre for Inherited Metabolic Diseases, Karolinska University Hospital, Stockholm SE-171 76, Sweden
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9
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El-Hattab AW, Craigen WJ, Scaglia F. Mitochondrial DNA maintenance defects. Biochim Biophys Acta Mol Basis Dis 2017; 1863:1539-1555. [PMID: 28215579 DOI: 10.1016/j.bbadis.2017.02.017] [Citation(s) in RCA: 166] [Impact Index Per Article: 23.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Revised: 01/31/2017] [Accepted: 02/14/2017] [Indexed: 01/12/2023]
Abstract
The maintenance of mitochondrial DNA (mtDNA) depends on a number of nuclear gene-encoded proteins including a battery of enzymes forming the replisome needed to synthesize mtDNA. These enzymes need to be in balanced quantities to function properly that is in part achieved by exchanging intramitochondrial contents through mitochondrial fusion. In addition, mtDNA synthesis requires a balanced supply of nucleotides that is achieved by nucleotide recycling inside the mitochondria and import from the cytosol. Mitochondrial DNA maintenance defects (MDMDs) are a group of diseases caused by pathogenic variants in the nuclear genes involved in mtDNA maintenance resulting in impaired mtDNA synthesis leading to quantitative (mtDNA depletion) and qualitative (multiple mtDNA deletions) defects in mtDNA. Defective mtDNA leads to organ dysfunction due to insufficient mtDNA-encoded protein synthesis, resulting in an inadequate energy production to meet the needs of affected organs. MDMDs are inherited as autosomal recessive or dominant traits, and are associated with a broad phenotypic spectrum ranging from mild adult-onset ophthalmoplegia to severe infantile fatal hepatic failure. To date, pathogenic variants in 20 nuclear genes known to be crucial for mtDNA maintenance have been linked to MDMDs, including genes encoding enzymes of mtDNA replication machinery (POLG, POLG2, TWNK, TFAM, RNASEH1, MGME1, and DNA2), genes encoding proteins that function in maintaining a balanced mitochondrial nucleotide pool (TK2, DGUOK, SUCLG1, SUCLA2, ABAT, RRM2B, TYMP, SLC25A4, AGK, and MPV17), and genes encoding proteins involved in mitochondrial fusion (OPA1, MFN2, and FBXL4).
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Affiliation(s)
- Ayman W El-Hattab
- Division of Clinical Genetics and Metabolic Disorders, Pediatrics Department, Tawam Hospital, Al-Ain, United Arab Emirates
| | - William J Craigen
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA.
| | - Fernando Scaglia
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
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10
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Anagnostou ME, Ng YS, Taylor RW, McFarland R. Epilepsy due to mutations in the mitochondrial polymerase gamma (POLG)
gene: A clinical and molecular genetic review. Epilepsia 2016; 57:1531-1545. [DOI: 10.1111/epi.13508] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/26/2016] [Indexed: 01/01/2023]
Affiliation(s)
- Maria-Eleni Anagnostou
- Wellcome Trust Centre for Mitochondrial Research; Institute of Neuroscience; Newcastle University; Newcastle upon Tyne United Kingdom
| | - Yi Shiau Ng
- Wellcome Trust Centre for Mitochondrial Research; Institute of Neuroscience; Newcastle University; Newcastle upon Tyne United Kingdom
| | - Robert W. Taylor
- Wellcome Trust Centre for Mitochondrial Research; Institute of Neuroscience; Newcastle University; Newcastle upon Tyne United Kingdom
| | - Robert McFarland
- Wellcome Trust Centre for Mitochondrial Research; Institute of Neuroscience; Newcastle University; Newcastle upon Tyne United Kingdom
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11
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Montassir H, Maegaki Y, Murayama K, Yamazaki T, Kohda M, Ohtake A, Iwasa H, Yatsuka Y, Okazaki Y, Sugiura C, Nagata I, Toyoshima M, Saito Y, Itoh M, Nishino I, Ohno K. Myocerebrohepatopathy spectrum disorder due to POLG mutations: A clinicopathological report. Brain Dev 2015; 37:719-24. [PMID: 25466440 DOI: 10.1016/j.braindev.2014.10.013] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/08/2014] [Revised: 10/06/2014] [Accepted: 10/26/2014] [Indexed: 10/24/2022]
Abstract
We report on the clinical, neuropathological, and genetic findings of a Japanese case with myocerebrohepatopathy spectrum (MCHS) disorder due to polymerase gamma (POLG) mutations. A girl manifested poor sucking and failure to thrive since 4 months of age and had frequent vomiting and developmental regression at 5 months of age. She showed significant hypotonia and hepatomegaly. Laboratory tests showed hepatocellular dysfunction and elevated protein and lactate levels in the cerebrospinal fluid. Her liver function and neurologic condition exacerbated, and she died at 8 months of age. At autopsy, fatty degeneration and fibrosis were observed in the liver. Neuropathological examination revealed white matter-predominant spongy changes with Alzheimer type II glia and loss of myelin. Enzyme activities of the respiratory chain complex I, III, and IV relative to citrate synthase in the muscle were normal in the biopsied muscle tissue, but they were reduced in the liver to 0%, 10%, and 14% of normal values, respectively. In the liver, the copy number of mitochondrial DNA compared to nuclear DNA was reduced to 3.3% of normal values as evaluated by quantitative polymerase chain reaction. Genetic analysis revealed compound heterozygous mutations for POLG (I1185T/A957V). This case represents the differential involvement of multiple organs and phenotype-specific distribution of brain lesions in mitochondrial DNA depletion disorders.
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Affiliation(s)
- Hesham Montassir
- Division of Child Neurology, Faculty of Medicine, Tottori University, Yonago, Japan; Department of Family Medicine, Faculty of Medicine, Cairo University, Cairo, Egypt
| | - Yoshihiro Maegaki
- Division of Child Neurology, Faculty of Medicine, Tottori University, Yonago, Japan.
| | - Kei Murayama
- Department of Metabolism, Chiba Children's Hospital, Chiba, Japan
| | - Taro Yamazaki
- Department of Pediatrics, School of Medicine, Saitama Medical University, Saitama, Japan
| | - Masakazu Kohda
- Division of Translational Research, Research Center for Genomic Medicine, Saitama Medical University, Hidaka, Japan
| | - Akira Ohtake
- Department of Pediatrics, School of Medicine, Saitama Medical University, Saitama, Japan
| | - Hiroyasu Iwasa
- Division of Translational Research, Research Center for Genomic Medicine, Saitama Medical University, Hidaka, Japan
| | - Yukiko Yatsuka
- Division of Functional Genomics & Systems Medicine, Research Center for Genomic Medicine, Saitama Medical University, Hidaka, Japan
| | - Yasushi Okazaki
- Division of Translational Research, Research Center for Genomic Medicine, Saitama Medical University, Hidaka, Japan; Division of Functional Genomics & Systems Medicine, Research Center for Genomic Medicine, Saitama Medical University, Hidaka, Japan
| | - Chitose Sugiura
- Division of Child Neurology, Faculty of Medicine, Tottori University, Yonago, Japan
| | - Ikuo Nagata
- Division of Pediatrics and Perinatology, Faculty of Medicine, Tottori University, Yonago, Japan
| | - Mitsuo Toyoshima
- Department of Pediatrics, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
| | - Yoshiaki Saito
- Division of Child Neurology, Faculty of Medicine, Tottori University, Yonago, Japan
| | - Masayuki Itoh
- Department of Mental Retardation and Birth Defect Research, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Ichizo Nishino
- Department of Neuromuscular Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Kousaku Ohno
- Division of Child Neurology, Faculty of Medicine, Tottori University, Yonago, Japan
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Hynynen J, Komulainen T, Tukiainen E, Nordin A, Arola J, Kälviäinen R, Jutila L, Röyttä M, Hinttala R, Majamaa K, Mäkisalo H, Uusimaa J. Acute liver failure after valproate exposure in patients with POLG1 mutations and the prognosis after liver transplantation. Liver Transpl 2014; 20:1402-12. [PMID: 25065347 DOI: 10.1002/lt.23965] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/16/2014] [Revised: 07/21/2014] [Accepted: 07/21/2014] [Indexed: 01/12/2023]
Abstract
Patients with mutations in the POLG1 gene encoding mitochondrial DNA polymerase gamma have an increased risk of valproate-induced liver failure. POLG1 mutations are common, and these patients often suffer from intractable seizures. The role of liver transplantation in the treatment of patients with mitochondrial diseases has been controversial. We studied valproate-induced liver failure associated with POLG1 mutations and the prognosis for these patients after liver transplantation. POLG1 was analyzed in blood DNA, mitochondrial DNA (mtDNA) was quantified in liver samples, and clinical data were collected. Five patients with valproate-induced liver failure associated with POLG1 mutations were retrospectively identified. Three patients were previously suspected to have Wilson's disease. Four patients with homozygous p.W748S and p.E1143G mutations had mtDNA depletion in the liver. One of these patients died before anticipated transplantation; the other 3 patients with liver transplantation have survived 4 to 19 years. Two patients have presented with occasional epileptic seizures, and 1 patient has been seizure-free for 11 years. One patient with a heterozygous p.Q1236H mutation (but without mtDNA depletion in the liver) died suddenly 2 years after liver transplantation. In conclusion, the POLG1 mutation status and the age at presentation of valproate-induced liver failure can affect the prognosis after liver transplantation. A heterozygous POLG1 p.Q1236H mutation was related to valproate-induced liver failure without mtDNA depletion, whereas patients homozygous for POLG1 p.W748S and p.E1143G mutations had mtDNA depletion. An analysis of the POLG1 gene should be performed for all patients with suspected mitochondrial disease before the introduction of valproate therapy, and treatment with valproic acid should be avoided in these patients.
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Affiliation(s)
- Johanna Hynynen
- Institute of Clinical Medicine, Department of Pediatrics, University of Oulu, Oulu, Finland; Medical Research Center, Oulu University Hospital, University of Oulu, Oulu, Finland
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13
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Qian Y, Kachroo AH, Yellman CM, Marcotte EM, Johnson KA. Yeast cells expressing the human mitochondrial DNA polymerase reveal correlations between polymerase fidelity and human disease progression. J Biol Chem 2014; 289:5970-85. [PMID: 24398692 DOI: 10.1074/jbc.m113.526418] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mutations in the human mitochondrial polymerase (polymerase-γ (Pol-γ)) are associated with various mitochondrial disorders, including mitochondrial DNA (mtDNA) depletion syndrome, Alpers syndrome, and progressive external opthamalplegia. To correlate biochemically quantifiable defects resulting from point mutations in Pol-γ with their physiological consequences, we created "humanized" yeast, replacing the yeast mtDNA polymerase (MIP1) with human Pol-γ. Despite differences in the replication and repair mechanism, we show that the human polymerase efficiently complements the yeast mip1 knockouts, suggesting common fundamental mechanisms of replication and conserved interactions between the human polymerase and other components of the replisome. We also examined the effects of four disease-related point mutations (S305R, H932Y, Y951N, and Y955C) and an exonuclease-deficient mutant (D198A/E200A). In haploid cells, each mutant results in rapid mtDNA depletion, increased mutation frequency, and mitochondrial dysfunction. Mutation frequencies measured in vivo equal those measured with purified enzyme in vitro. In heterozygous diploid cells, wild-type Pol-γ suppresses mutation-associated growth defects, but continuous growth eventually leads to aerobic respiration defects, reduced mtDNA content, and depolarized mitochondrial membranes. The severity of the Pol-γ mutant phenotype in heterozygous diploid humanized yeast correlates with the approximate age of disease onset and the severity of symptoms observed in humans.
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Affiliation(s)
- Yufeng Qian
- From the Institute for Cellular and Molecular Biology
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14
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Rouzier C, Chaussenot A, Serre V, Fragaki K, Bannwarth S, Ait-El-Mkadem S, Attarian S, Kaphan E, Cano A, Delmont E, Sacconi S, Mousson de Camaret B, Rio M, Lebre AS, Jardel C, Deschamps R, Richelme C, Pouget J, Chabrol B, Paquis-Flucklinger V. Quantitative multiplex PCR of short fluorescent fragments for the detection of large intragenic POLG rearrangements in a large French cohort. Eur J Hum Genet 2013; 22:542-50. [PMID: 23921535 DOI: 10.1038/ejhg.2013.171] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2012] [Revised: 05/21/2013] [Accepted: 06/19/2013] [Indexed: 01/03/2023] Open
Abstract
Polymerase gamma (POLG) is the gene most commonly involved in mitochondrial disorders with mitochondrial DNA instability and causes a wide range of diseases with recessive or dominant transmission. More than 170 mutations have been reported. Most of them are missense mutations, although nonsense mutations, splice-site mutations, small deletions and insertions have also been identified. However, to date, only one large-scale rearrangement has been described in a child with Alpers syndrome. Below, we report a large cohort of 160 patients with clinical, molecular and/or biochemical presentation suggestive of POLG deficiency. Using sequencing, we identified POLG variants in 22 patients (18 kindreds) including five novel pathogenic mutations. Two patients with novel mutations had unusual clinical presentation: the first exhibited an isolated ataxic neuropathy and the second was a child who presented with endocrine signs. We completed the sequencing step by quantitative multiplex PCR of short fluorescent fragments (QMPSF) analysis in 37 patients with either only one POLG heterozygous variant or a family history suggesting a dominant transmission. We identified a large intragenic deletion encompassing part of intron 21 and exon 22 of POLG in a child with refractory epilepsia partialis continua. In conclusion, we describe the first large French cohort of patients with POLG mutations, expanding the wide clinical and molecular spectrum observed in POLG disease. We confirm that large deletions in the POLG gene are rare events and we highlight the importance of QMPSF in patients with a single heterozygous POLG mutation, particularly in severe infantile phenotypes.
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Affiliation(s)
- Cécile Rouzier
- 1] Department of Medical Genetics, National Centre for Mitochondrial diseases, Nice Teaching Hospital, Nice, France [2] IRCAN, CNRS UMR 7284/INSERM U1081/UNS, School of Medicine, Nice Sophia-Antipolis University, Nice, France
| | - Annabelle Chaussenot
- Department of Medical Genetics, National Centre for Mitochondrial diseases, Nice Teaching Hospital, Nice, France
| | - Valérie Serre
- Jacques Monod Institute, CNRS-University Paris Diderot, Sorbonne, Paris, France
| | - Konstantina Fragaki
- 1] Department of Medical Genetics, National Centre for Mitochondrial diseases, Nice Teaching Hospital, Nice, France [2] IRCAN, CNRS UMR 7284/INSERM U1081/UNS, School of Medicine, Nice Sophia-Antipolis University, Nice, France
| | - Sylvie Bannwarth
- 1] Department of Medical Genetics, National Centre for Mitochondrial diseases, Nice Teaching Hospital, Nice, France [2] IRCAN, CNRS UMR 7284/INSERM U1081/UNS, School of Medicine, Nice Sophia-Antipolis University, Nice, France
| | - Samira Ait-El-Mkadem
- 1] Department of Medical Genetics, National Centre for Mitochondrial diseases, Nice Teaching Hospital, Nice, France [2] IRCAN, CNRS UMR 7284/INSERM U1081/UNS, School of Medicine, Nice Sophia-Antipolis University, Nice, France
| | - Shahram Attarian
- Department of Neurology, Timone Hospital, Marseille Teaching Hospital, Marseille, France
| | - Elsa Kaphan
- Department of Neurology, Timone Hospital, Marseille Teaching Hospital, Marseille, France
| | - Aline Cano
- Department of Neuropediatrics, Timone Hospital, Marseille Teaching Hospital, Marseille, France
| | - Emilien Delmont
- Department of Neurology, Nice Teaching Hospital, Nice, France
| | - Sabrina Sacconi
- Department of Neurology, Nice Teaching Hospital, Nice, France
| | | | - Marlène Rio
- Department of Medical Genetics, Necker Hospital, Paris Teaching Hospital, Paris, France
| | - Anne-Sophie Lebre
- Department of Medical Genetics, Necker Hospital, Paris Teaching Hospital, Paris, France
| | - Claude Jardel
- Department of Molecular and Chromosomal Genetics, Pitié-Salpétrière Hospital, Paris Teaching Hospital, Paris, France
| | - Romain Deschamps
- Department of Neuromuscular disorders, Fort-de-France Teaching Hospital, Martinique, France
| | - Christian Richelme
- Department of Pediatrics, Lenval Hospital, Nice Teaching Hospital, Nice, France
| | - Jean Pouget
- Department of Neurology, Timone Hospital, Marseille Teaching Hospital, Marseille, France
| | - Brigitte Chabrol
- Department of Neuropediatrics, Timone Hospital, Marseille Teaching Hospital, Marseille, France
| | - Véronique Paquis-Flucklinger
- 1] Department of Medical Genetics, National Centre for Mitochondrial diseases, Nice Teaching Hospital, Nice, France [2] IRCAN, CNRS UMR 7284/INSERM U1081/UNS, School of Medicine, Nice Sophia-Antipolis University, Nice, France
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15
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Scheibye-Knudsen M, Croteau DL, Bohr VA. Mitochondrial deficiency in Cockayne syndrome. Mech Ageing Dev 2013; 134:275-83. [PMID: 23435289 PMCID: PMC3663877 DOI: 10.1016/j.mad.2013.02.007] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2012] [Revised: 01/24/2013] [Accepted: 02/08/2013] [Indexed: 01/05/2023]
Abstract
Cockayne syndrome is a rare inherited disorder characterized by accelerated aging, cachectic dwarfism and many other features. Recent work has implicated mitochondrial dysfunction in the pathogenesis of this disease. This is particularly interesting since mitochondrial deficiencies are believed to be important in the aging process. In this review, we discuss recent findings of mitochondrial pathology in Cockayne syndrome and suggest possible mechanisms for the mitochondrial dysfunction.
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Affiliation(s)
| | - Deborah L. Croteau
- Laboratory of Molecular Gerontology, National Institute on Aging, NIH, USA
| | - Vilhelm A. Bohr
- Laboratory of Molecular Gerontology, National Institute on Aging, NIH, USA
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16
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Scalais E, Francois B, Schlesser P, Stevens R, Nuttin C, Martin JJ, Van Coster R, Seneca S, Roels F, Van Goethem G, Löfgren A, De Meirleir L. Polymerase gamma deficiency (POLG): clinical course in a child with a two stage evolution from infantile myocerebrohepatopathy spectrum to an Alpers syndrome and neuropathological findings of Leigh's encephalopathy. Eur J Paediatr Neurol 2012; 16:542-8. [PMID: 22342071 DOI: 10.1016/j.ejpn.2012.01.013] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/17/2011] [Revised: 01/11/2012] [Accepted: 01/26/2012] [Indexed: 11/19/2022]
Abstract
AIMS Description of the clinical course in a child compound heterozygous for POLG1 mutations, neuropathology findings and results of dietary treatment based on fasting avoidance and long chain triglycerides (LCT) restriction. RESULTS At 3(1/2) months of age the patient presented with severe hypoglycemia, hyperlactatemia, moderate ketosis and hepatic failure. Fasting hypoglycemia occurred 8 h after meals. The hypoglycemia did not respond to glucagon. She was supplemented with IV glucose and/or frequent feedings, but developed liver insufficiency which was reversed by long-chain triglyceride (LCT) restriction. Alpha-foeto-protein (AFP) levels were elevated and returned to low values after dietary treatment. Liver biopsy displayed cirrhosis, bile ductular proliferation, steatosis, isolated complex IV defect in part of the liver mitochondria, and mitochondrial DNA depletion (27% of control values). Two heterozygous mutations (p. [Ala467Thr] + p. [Gly848Ser]) were found in the POLG1 gene. At 3 years of age she progressively developed refractory mixed type seizures including a focal component and psychomotor regression which fulfilled the criteria of Alpers syndrome (AS) although the initial presentation was compatible with infantile myocerebrohepatopathy spectrum (MCHS). She died at 5 years of age of respiratory insufficiency. Neuropathologic investigation revealed lesions in the right striatal area and the inferior colliculi typical for Leigh's encephalopathy. CONCLUSION The present patient showed an evolution from infantile MCHS to AS, and dietary treatment seemed to slow the progression of liver failure. In spite of the late clinical features of AS, it extends the neuropathological spectrum of AS and polymerase gamma deficiency (POLG) to Leigh syndrome lesions.
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Affiliation(s)
- Emmanuel Scalais
- Division of Paediatric Neurology, Centre Hospitalier de Luxembourg, Luxembourg.
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17
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Palin EJH, Hakonen AH, Korpela M, Paetau A, Suomalainen A. Mitochondrial recessive ataxia syndrome mimicking dominant spinocerebellar ataxia. J Neurol Sci 2011; 315:160-3. [PMID: 22166854 DOI: 10.1016/j.jns.2011.11.028] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2011] [Revised: 11/16/2011] [Accepted: 11/22/2011] [Indexed: 10/14/2022]
Abstract
We studied the genetic background of a family with SCA, showing dominant inheritance and anticipation. Muscle histology, POLG1 gene sequence, neuropathology and mitochondrial DNA analyses in a mother and a son showed typical findings for a mitochondrial disorder, and both were shown to be homozygous for a recessive POLG1 mutation, underlying mitochondrial recessive ataxia syndrome, MIRAS. The healthy father was a heterozygous carrier for the same mutation. Recessively inherited MIRAS mutations should be tested in dominantly inherited SCAs cases of unknown cause, as the high carrier frequency of MIRAS may result in two independent introductions of the mutant allele in the family and thereby mimic dominant inheritance.
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Affiliation(s)
- Eino J H Palin
- Research Programs Unit, Molecular Neurology, University of Helsinki, Helsinki, Finland.
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18
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Lindroos MM, Borra R, Mononen N, Lehtimäki T, Virtanen KA, Lepomäki V, Guiducci L, Iozzo P, Majamaa K, Nuutila P. Mitochondrial diabetes is associated with insulin resistance in subcutaneous adipose tissue but not with increased liver fat content. J Inherit Metab Dis 2011; 34:1205-12. [PMID: 21556834 DOI: 10.1007/s10545-011-9338-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/08/2011] [Revised: 03/27/2011] [Accepted: 04/07/2011] [Indexed: 12/18/2022]
Abstract
We recently showed that patients with mitochondrial diabetes are insulin resistant in skeletal muscle before the decline in insulin secretion is observed. In this study, we further evaluate whether insulin resistance is associated with increased ectopic fat accumulation and altered adipose and hepatic tissue insulin sensitivity. We studied 15 nonobese patients with the m.3243A > G mutation. Five were without diabetes (group 1), three had newly diagnosed diabetes (group 2), and seven had previously diagnosed diabetes (group 3). Thirteen healthy volunteers of similar age and body mass index (BMI) served as controls. Insulin-stimulated glucose uptake was measured with positron emission tomography using 2- [(18)F]-fluoro-2-deoxyglucose during euglycemic hyperinsulinemia. Fat masses and liver fat content were measured with magnetic resonance imaging and spectroscopy. Compared with controls, insulin-stimulated glucose uptake in adipose tissue was decreased by ∼50% in all groups with the m.3243A > G mutation. In addition, fat masses were not different, but insulin-mediated suppression of lipolysis and adiponectin metabolism were blunted in patients with the m.3243A > G mutation. Hepatic fat content was normal (<5.6%) in 80% of patients and significantly elevated in one case only. Hepatic glucose metabolism in patients with m.3243A > G did not differ from that of controls. In conclusion, m.3243A > G mutation affects subcutaneous adipose tissue metabolism. This seems to occur before aberrant liver metabolism, if any, can be observed or before beta-cell failure results in mitochondrial diabetes.
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Affiliation(s)
- Markus M Lindroos
- Turku PET Centre, University of Turku and Turku University Hospital, P.O. Box 52, FIN-20521, Turku, Finland.
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Pronicka E, Weglewska-Jurkiewicz A, Pronicki M, Sykut-Cegielska J, Kowalski P, Pajdowska M, Jankowska I, Kotulska K, Kalicinski P, Jakobkiewicz-Banecka J, Wegrzyn G. Drug-resistant epilepsia and fulminant valproate liver toxicity. Alpers-Huttenlocher syndrome in two children confirmed post mortem by identification of p.W748S mutation in POLG gene. Med Sci Monit 2011; 17:CR203-9. [PMID: 21455106 PMCID: PMC3539522 DOI: 10.12659/msm.881716] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Background POLG (polymerase gamma) gene mutations lead to a variety of neurological disorders, including Alpers-Huttenlocher syndrome (AHS). The diagnostic triad of AHS is: resistant epilepsy, liver impairment triggered by sodium valproate (VA), and mitochondrial DNA depletion. Material/Methods A cohort of 28 children with mitochondrial encephalopathy and liver failure was qualified for retrospective study of mitochondrial DNA depletion and POLG mutations. Results The p.W748S POLG gene mutation was revealed in 2 children, the only ones in the cohort who fulfilled the AHS criteria. Depletion of mtDNA (16% of control value) was confirmed post mortem in available liver tissue and was not detected in the muscle. The disease started with drug-resistant seizures, failure to thrive and developmental regression at the ages of 7 and 18 months, respectively. Irreversible liver failure developed after VA administration. Co-existence of epilepsy, VA liver toxicity, lactic acidemia and muscle respiratory chain dysfunction led finally to the diagnosis of mitochondrial disorder (and AHS suspicion). Conclusions Our results confirm, for the first time, the occurrence of a pathology caused by POLG gene mutation(s) in the Polish population. POLG mutation screening and mtDNA depletion assessment should be included in differential diagnosis of drug-resistant epilepsy associated with a hepatopathy.
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Affiliation(s)
- Ewa Pronicka
- Department of Metabolic Diseases, Endocrinology and Diabetology, Children's Memorial Health Institute Warsaw, Poland.
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Mousson de Camaret B, Chassagne M, Mayençon M, Padet S, Crehalet H, Clerc-Renaud P, Rouvet I, Zabot MT, Rivier F, Sarda P, des Portes V, Bozon D. POLG exon 22 skipping induced by different mechanisms in two unrelated cases of Alpers syndrome. Mitochondrion 2011; 11:223-7. [DOI: 10.1016/j.mito.2010.07.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2010] [Revised: 06/29/2010] [Accepted: 07/23/2010] [Indexed: 11/16/2022]
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Predicting the contribution of novel POLG mutations to human disease through analysis in yeast model. Mitochondrion 2010; 11:182-90. [PMID: 20883824 DOI: 10.1016/j.mito.2010.09.007] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2010] [Revised: 09/17/2010] [Accepted: 09/20/2010] [Indexed: 11/24/2022]
Abstract
The yeast Saccharomyces cerevisiae was used to validate the pathogenic significance of eight human mutations in the gene encoding for the mitochondrial DNA polymerase gamma, namely G303R, S305R, R386H, R574W, P625R, D930N, K947R and P1073L, among which three are novel and four are of unclear pathological significance. Mitochondrial DNA extended and point mutability as well as dominance/recessivity of each mutation has been evaluated. The analysis in yeast revealed that two mutations, S305R and R386H, cannot be the sole cause of pathology observed in patients. These data led us to search for a second mutation in compound with S305R and we found a mutation, P1073L, missed in the first genetic analysis. Finally, a significant rescue of extended mutability has been observed for several dominant mutations by treatment with mitochondrial antioxidants.
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