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Bacalhau M, Simões M, Rocha MC, Hardy SA, Vincent AE, Durães J, Macário MC, Santos MJ, Rebelo O, Lopes C, Pratas J, Mendes C, Zuzarte M, Rego AC, Girão H, Wong LJC, Taylor RW, Grazina M. Disclosing the functional changes of two genetic alterations in a patient with Chronic Progressive External Ophthalmoplegia: Report of the novel mtDNA m.7486G>A variant. Neuromuscul Disord 2018; 28:350-360. [PMID: 29398297 PMCID: PMC5952895 DOI: 10.1016/j.nmd.2017.11.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2017] [Revised: 11/14/2017] [Accepted: 11/15/2017] [Indexed: 01/06/2023]
Abstract
Chronic Progressive External Ophthalmoplegia (CPEO) is characterized by ptosis and ophthalmoplegia and is usually caused by mitochondrial DNA (mtDNA) deletions or mt-tRNA mutations. The aim of the present work was to clarify the genetic defect in a patient presenting with CPEO and elucidate the underlying pathogenic mechanism. This 62-year-old female first developed ptosis of the right eye at the age of 12 and subsequently the left eye at 45 years, and was found to have external ophthalmoplegia at the age of 55 years. Histopathological abnormalities were detected in the patient's muscle, including ragged-red fibres, a mosaic pattern of COX-deficient muscle fibres and combined deficiency of respiratory chain complexes I and IV. Genetic investigation revealed the "common deletion" in the patient's muscle and fibroblasts. Moreover, a novel, heteroplasmic mt-tRNASer(UCN) variant (m.7486G>A) in the anticodon loop was detected in muscle homogenate (50%), fibroblasts (11%) and blood (4%). Single-fibre analysis showed segregation with COX-deficient fibres for both genetic alterations. Assembly defects of mtDNA-encoded complexes were demonstrated in fibroblasts. Functional analyses showed significant bioenergetic dysfunction, reduction in respiration rate and ATP production and mitochondrial depolarization. Multilamellar bodies were detected by electron microscopy, suggesting disturbance in autophagy. In conclusion, we report a CPEO patient with two possible genetic origins, both segregating with biochemical and histochemical defect. The "common mtDNA deletion" is the most likely cause, yet the potential pathogenic effect of a novel mt-tRNASer(UCN) variant cannot be fully excluded.
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Affiliation(s)
- Mafalda Bacalhau
- FMUC - Faculty of Medicine, University of Coimbra, Coimbra, Portugal; CNC - Center for Neuroscience and Cell Biology, Laboratory of Biochemical Genetics, University of Coimbra, Coimbra, Portugal
| | - Marta Simões
- CNC - Center for Neuroscience and Cell Biology, Laboratory of Biochemical Genetics, University of Coimbra, Coimbra, Portugal
| | - Mariana C Rocha
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Newcastle Upon Tyne, UK
| | - Steven A Hardy
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Newcastle Upon Tyne, UK
| | - Amy E Vincent
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Newcastle Upon Tyne, UK
| | - João Durães
- CHUC - Neurology Department of Coimbra University Hospitals, Coimbra, Portugal
| | - Maria C Macário
- CHUC - Neurology Department of Coimbra University Hospitals, Coimbra, Portugal
| | - Maria João Santos
- FMUC - Faculty of Medicine, University of Coimbra, Coimbra, Portugal; CNC - Center for Neuroscience and Cell Biology, Laboratory of Biochemical Genetics, University of Coimbra, Coimbra, Portugal
| | - Olinda Rebelo
- CHUC - Neurology Department of Coimbra University Hospitals, Coimbra, Portugal
| | - Carla Lopes
- CNC - Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal
| | - João Pratas
- CNC - Center for Neuroscience and Cell Biology, Laboratory of Biochemical Genetics, University of Coimbra, Coimbra, Portugal
| | - Cândida Mendes
- CNC - Center for Neuroscience and Cell Biology, Laboratory of Biochemical Genetics, University of Coimbra, Coimbra, Portugal
| | - Mónica Zuzarte
- IBILI - Institute for Biomedical Imaging and Life Sciences, University of Coimbra, Coimbra, Portugal
| | - A Cristina Rego
- FMUC - Faculty of Medicine, University of Coimbra, Coimbra, Portugal; CNC - Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal
| | - Henrique Girão
- FMUC - Faculty of Medicine, University of Coimbra, Coimbra, Portugal; IBILI - Institute for Biomedical Imaging and Life Sciences, University of Coimbra, Coimbra, Portugal
| | - Lee-Jun C Wong
- Mitochondrial Diagnostic Laboratory, Baylor College of Medicine, Houston, USA
| | - Robert W Taylor
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Newcastle Upon Tyne, UK
| | - Manuela Grazina
- FMUC - Faculty of Medicine, University of Coimbra, Coimbra, Portugal; CNC - Center for Neuroscience and Cell Biology, Laboratory of Biochemical Genetics, University of Coimbra, Coimbra, Portugal.
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Finsterer J, Zarrouk-Mahjoub S, Daruich A. The Eye on Mitochondrial Disorders. J Child Neurol 2016; 31:652-62. [PMID: 26275973 DOI: 10.1177/0883073815599263] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/11/2015] [Accepted: 07/08/2015] [Indexed: 11/16/2022]
Abstract
Ophthalmologic manifestations of mitochondrial disorders are frequently neglected or overlooked because they are often not regarded as part of the phenotype. This review aims at summarizing and discussing the etiology, pathogenesis, diagnosis, and treatment of ophthalmologic manifestations of mitochondrial disorders. Review of publications about ophthalmologic involvement in mitochondrial disorders by search of Medline applying appropriate search terms. The eye is frequently affected by syndromic as well as nonsyndromic mitochondrial disorders. Primary and secondary ophthalmologic manifestations can be differentiated. The most frequent ophthalmologic manifestations of mitochondrial disorders include ptosis, progressive external ophthalmoplegia, optic atrophy, retinopathy, and cataract. More rarely occurring are nystagmus and abnormalities of the cornea, ciliary body, intraocular pressure, the choroidea, or the brain secondarily affecting the eyes. It is important to recognize and diagnose ophthalmologic manifestations of mitochondrial disorders as early as possible because most are accessible to symptomatic treatment with partial or complete short-term or long-term beneficial effect. Ophthalmologic manifestations of mitochondrial disorders need to be appropriately diagnosed to initiate the most effective management and guarantee optimal outcome.
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Affiliation(s)
| | | | - Alejandra Daruich
- Department of Ophthalmology, University of Lausanne, Jules-Gonin Eye Hospital, Switzerland
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3
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Filosto M, Lanzi G, Nesti C, Vielmi V, Marchina E, Galvagni A, Giliani S, Santorelli FM, Padovani A. A novel mitochondrial tRNA(Ala) gene variant causes chronic progressive external ophthalmoplegia in a patient with Huntington disease. Mol Genet Metab Rep 2016; 6:70-3. [PMID: 27014581 PMCID: PMC4789388 DOI: 10.1016/j.ymgmr.2016.02.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2016] [Accepted: 02/07/2016] [Indexed: 12/14/2022] Open
Abstract
Chronic progressive external ophthalmoplegia is a mitochondrial disorder usually caused by single or multiple mitochondrial DNA (mtDNA) deletions and, more rarely, by maternally inherited mtDNA point mutations, most frequently in tRNA genes (MTT). We report on a patient presenting with a progressive eyelid ptosis with bilateral ophthalmoparesis, dysphagia, dysphonia and mild proximal limb weakness associate with a mild movement disorder characterized by abnormal involuntary movements involving head and limbs, imbalance and gait instability. Muscle biopsy demonstrated the presence of ragged red fibers and several cytochrome-C-oxidase negative fibers. Molecular analysis showed the novel m.5613T > C heteroplasmic mutation in the mitochondrial tRNA(Ala) gene (MTTA) which disrupts a conserved site and fulfills the accepted criteria of pathogenicity. Moreover, a 38 CAG trinucleotide repeat expansion was found on the huntingtin gene, thus configuring a singular CPEO/"reduced penetrance" Huntington disease "double trouble". With this novel MTTA point mutation, we extend the spectrum of provisional pathogenic changes in this gene, which is a very rare site of pathogenic mutation, and confirm that clinical expression of these mutations is hardly ever heterogeneous, including myopathy and CPEO. Mitochondrial involvement is an emerging key determinant in the pathogenesis of Huntington disease and it is well known that mutant huntingtin influences the mitochondrial respiratory complexes II and III. A synergist effect of the HTT and MTTA mutations on respiratory chain function may be hypothesized in our patient and should be regarded as a spur for further studies on the mtDNA/HTT reciprocal interactions.
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Affiliation(s)
- Massimiliano Filosto
- Clinical Neurology, Section for Neuromuscular Diseases and Neuropathies, University Hospital “Spedali Civili”, Brescia, Italy
| | - Gaetana Lanzi
- Institute of Molecular Medicine “A. Nocivelli”, University Hospital “Spedali Civili”, Brescia, Italy
| | - Claudia Nesti
- Unit of Molecular Medicine, IRCCS Stella Maris, Pisa, Italy
| | - Valentina Vielmi
- Clinical Neurology, Section for Neuromuscular Diseases and Neuropathies, University Hospital “Spedali Civili”, Brescia, Italy
| | - Eleonora Marchina
- Division of Biology and Genetics, Department of Biomedical Sciences and Biotechnology, University of Brescia, Italy
| | - Anna Galvagni
- Clinical Neurology, Section for Neuromuscular Diseases and Neuropathies, University Hospital “Spedali Civili”, Brescia, Italy
| | - Silvia Giliani
- Institute of Molecular Medicine “A. Nocivelli”, University Hospital “Spedali Civili”, Brescia, Italy
| | | | - Alessandro Padovani
- Clinical Neurology, Section for Neuromuscular Diseases and Neuropathies, University Hospital “Spedali Civili”, Brescia, Italy
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4
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Jackson CB, Neuwirth C, Hahn D, Nuoffer JM, Frank S, Gallati S, Schaller A. Novel mitochondrial tRNA(Ile) m.4282A>G gene mutation leads to chronic progressive external ophthalmoplegia plus phenotype. Br J Ophthalmol 2014; 98:1453-9. [PMID: 25034047 DOI: 10.1136/bjophthalmol-2014-305300] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
BACKGROUND/AIM To investigate the underlying pathomechanism in a 33-year-old female Caucasian patient presenting with chronic progressive external ophthalmoplegia (CPEO) plus symptoms. METHODS Histochemical analysis of skeletal muscle and biochemical measurements of individual oxidative phosphorylation (OXPHOS) complexes. Genetic analysis of mitochondrial DNA in various tissues with subsequent investigation of single muscle fibres for correlation of mutational load. RESULTS The patient's skeletal muscle showed 20% of cytochrome c oxidase-negative fibres and 8% ragged-red fibres. Genetic analysis of the mitochondrial DNA revealed a novel point mutation in the mitochondrial tRNA(Ile) (MTTI) gene at position m.4282G>A. The heteroplasmy was determined in blood, buccal cells and muscle by restriction fragment length polymorphism (RFLP) combined with a last fluorescent cycle. The total mutational load was 38% in skeletal muscle, but was not detectable in blood or buccal cells of the patient. The phenotype segregated with the mutational load as determined by analysis of single cytochrome c oxidase-negative/positive fibres by laser capture microdissection and subsequent LFC-RFLP. CONCLUSIONS We describe a novel MTTI transition mutation at nucleotide position m.4282G>A associated with a CPEO plus phenotype. The novel variant at position m.4282G>A disrupts the middle bond of the D-stem of the tRNA(Ile) and is highly conserved. The conservation and phenotype-genotype segregation strongly suggest pathogenicity and is in good agreement with the MTTI gene being frequently associated with CPEO. This novel variant broadens the spectrum of MTTI mutations causing CPEO.
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Affiliation(s)
- Christopher B Jackson
- Division of Human Genetics, Departments of Pediatrics and Clinical Research, Inselspital, University of Berne, Berne, Switzerland Institute of Clinical Chemistry, Inselspital, University of Berne, Berne, Switzerland Graduate School for Cellular and Biomedical Sciences, University of Berne, Berne, Switzerland
| | - Christoph Neuwirth
- Neuromuscular Diseases Centre, Cantonal Hospital St.Gallen, St.Gallen, Switzerland
| | - Dagmar Hahn
- Institute of Clinical Chemistry, Inselspital, University of Berne, Berne, Switzerland
| | - J-M Nuoffer
- Institute of Clinical Chemistry, Inselspital, University of Berne, Berne, Switzerland
| | - Stephan Frank
- Division of Neuropathology, Institute of Pathology, Basle University Hospital, Basle, Switzerland
| | - Sabina Gallati
- Division of Human Genetics, Departments of Pediatrics and Clinical Research, Inselspital, University of Berne, Berne, Switzerland
| | - André Schaller
- Division of Human Genetics, Departments of Pediatrics and Clinical Research, Inselspital, University of Berne, Berne, Switzerland
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5
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Zhao D, Wang Z, Hong D, Zhang W, Yuan Y. Chronic progressive external ophthalmoplegia coexistent with motor neuron disease in a patient with a novel large-scale mitochondrial DNA deletion. Clin Neurol Neurosurg 2012; 115:1490-2. [PMID: 23266267 DOI: 10.1016/j.clineuro.2012.11.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2012] [Revised: 11/17/2012] [Accepted: 11/20/2012] [Indexed: 11/18/2022]
Affiliation(s)
- Danhua Zhao
- Department of Neurology, Peking University First Hospital, Beijing 100034, PR China
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6
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Gorman GS, Taylor RW. Mitochondrial DNA abnormalities in ophthalmological disease. Saudi J Ophthalmol 2011; 25:395-404. [PMID: 23960954 DOI: 10.1016/j.sjopt.2011.02.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2011] [Revised: 02/07/2011] [Accepted: 02/12/2011] [Indexed: 01/13/2023] Open
Abstract
Mitochondrial disorders are a group of clinically heterogeneous diseases, commonly defined by lack of cellular energy due to genetic defects of oxidative phosphorylation (OXPHOS). Ocular involvement is a prominent clinical feature of mitochondrial disease. This can manifest as optic nerve dysfunction specifically involving retinal ganglion cells as typified by Leber hereditary optic neuropathy (LHON), or progressive external ophthalmoplegia (PEO) and ptosis involving the extraocular muscles which is commonly associated with either primary mitochondrial DNA (mtDNA) mutations or acquired mtDNA defects secondary to a nuclear genetic disorder of mtDNA maintenance. In this short review, we will outline the unique characteristics of mitochondrial genetic disease and its investigation with reference to the clinical features and molecular genetic abnormalities underlying mitochondrial ophthalmological disease.
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Affiliation(s)
- Grainne S Gorman
- Mitochondrial Research Group, Institute for Ageing and Health, Newcastle University, United Kingdom
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7
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Emmanuele V, Sotiriou E, Shirazi M, Tanji K, Haller RG, Heinicke K, Bosch PE, Hirano M, DiMauro S. Recurrent myoglobinuria in a sporadic patient with a novel mitochondrial DNA tRNA(Ile) mutation. J Neurol Sci 2011; 303:39-42. [PMID: 21324494 DOI: 10.1016/j.jns.2011.01.018] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2010] [Revised: 01/06/2011] [Accepted: 01/14/2011] [Indexed: 01/04/2023]
Abstract
The differential diagnosis of myoglobinuria includes multiple etiologies, such as infection, inflammation, trauma, endocrinopathies, drugs toxicity, and primary metabolic disorders. Metabolic myopathies can be due to inherited disorders of glycogen metabolism or to defects of fatty acid oxidation. Primary respiratory chain dysfunction is a rare cause of myoglobinuria, but it has been described in sporadic cases with mutations in genes encoding cytochrome b or cytochrome c oxidase (COX) subunits and in four cases with tRNA mutations. We describe a 39-year-old woman with myalgia and exercise-related recurrent myoglobinuria, who harbored a novel mitochondrial DNA mutation at nucleotide 4281 (m.4281A>G) in the tRNA-isoleucine gene. Her muscle biopsy revealed ragged-red and COX-deficient fibers. No deletions or duplication were detected by Southern blot analysis. The m.4281A>G mutation was present in the patient's muscle with a mutation load of 46% and was detected in trace amounts in urine and cheek mucosa. Single-fiber analysis revealed significantly higher levels of the mutation in COX-deficient (65%) than in normal fibers (45%). This novel mutation has to be added to the molecular causes of recurrent myoglobinuria.
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Affiliation(s)
- Valentina Emmanuele
- Department of Neurology, Columbia University Medical Center, New York, NY, USA
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8
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Schaller A, Desetty R, Hahn D, Jackson CB, Nuoffer JM, Gallati S, Levinger L. Impairment of mitochondrial tRNAIle processing by a novel mutation associated with chronic progressive external ophthalmoplegia. Mitochondrion 2011; 11:488-96. [PMID: 21292040 DOI: 10.1016/j.mito.2011.01.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2010] [Revised: 12/27/2010] [Accepted: 01/24/2011] [Indexed: 10/18/2022]
Abstract
We report a sporadic case of chronic progressive external ophthalmoplegia associated with ragged red fibers. The patient presented with enlarged mitochondria with deranged internal architecture and crystalline inclusions. Biochemical studies showed reduced activities of complex I, III and IV in skeletal muscle. Molecular genetic analysis of all mitochondrial tRNAs revealed a G to A transition at nt 4308; the G is a highly conserved nucleotide that participates in a GC base-pair in the T-stem of mammalian mitochondrial tRNA(Ile). The mutation was detected at a high level (approx. 50%) in muscle but not in blood. The mutation co-segregated with the phenotype, as the mutation was absent from blood and muscle in the patient's healthy mother. Functional characterization of the mutation revealed a six-fold reduced rate of tRNA(Ile) precursor 3' end maturation in vitro by tRNAse Z. Furthermore, the mutated tRNA(Ile) displays local structural differences from wild-type. These results suggest that structural perturbations reduce efficiency of tRNA(Ile) precursor 3' end processing and contribute to the molecular pathomechanism of this mutation.
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Affiliation(s)
- A Schaller
- Division of Human Genetics, University Hospital Bern, Switzerland.
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9
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Sundaram C, Meena AK, Uppin MS, Govindaraj P, Vanniarajan A, Thangaraj K, Kaul S, Kekunnaya R, Murthy JMK. Contribution of muscle biopsy and genetics to the diagnosis of chronic progressive external opthalmoplegia of mitochondrial origin. J Clin Neurosci 2011; 18:535-8. [PMID: 21277779 DOI: 10.1016/j.jocn.2010.06.014] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2010] [Revised: 06/07/2010] [Accepted: 06/14/2010] [Indexed: 11/18/2022]
Abstract
Chronic progressive external opthalmoplegia (CPEO) is the most common phenotypic syndrome of the mitochondrial myopathies. Muscle biopsy, which provides important morphological clues for the diagnosis of mitochondrial disorders, is normal in approximately 25% of patients with CPEO, thus necessitating molecular genetic analysis for more accurate diagnosis. We aimed to study the utility of various histochemical stains in the diagnosis of CPEO on muscle biopsy and to correlate these results with genetic studies. Between May 2005 and November 2007 all 45 patients diagnosed with CPEO were included in the study (23 males; mean age at presentation, 35 years). Thirty-nine patients had CPEO only and six had CPEO plus; two had a positive family history but the remaining 39 patients had sporadic CPEO. Muscle biopsy samples were stained with hematoxylin and eosin, modified Gomori's trichrome stain, succinic dehydrogenase (SDH), cytochrome C oxidase (COX) and combined COX-SDH. Ragged red fibers were seen in 27 biopsies; seven showed characteristics of neurogenic atrophy only, and 11 were normal. The abnormal fibers were best identified on COX-SDH stain. A complete mitochondrial genome was amplified in muscle and blood samples of all patients. Mutations were found in transfer RNA, ribosomal RNA, ND, CYTB, COX I, II and III genes. Mitochondrial gene mutations were found in ten of the 11 patients with a normal muscle biopsy. The genetic mutations were classified according to their significance. The observed muscle biopsy findings were correlated with genetic mutations noted. Histological studies should be combined with genetic studies for the definitive diagnosis of CPEO syndrome.
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Affiliation(s)
- Challa Sundaram
- Department of Pathology, Nizam's Institute Medical Sciences, Punjagutta, Hyderabad 500082, Andhra Pradesh, India.
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10
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A novel mutation in the mitochondrial tRNAAla gene (m.5636T>C) in a patient with progressive external ophthalmoplegia. Mitochondrion 2011; 11:228-33. [DOI: 10.1016/j.mito.2010.08.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2010] [Revised: 07/21/2010] [Accepted: 08/20/2010] [Indexed: 11/23/2022]
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11
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Souilem S, Chebel S, Mancuso M, Petrozzi L, Siciliano G, FrihAyed M, Hentati F, Amouri R. A novel mitochondrial tRNA(Ile) point mutation associated with chronic progressive external ophthalmoplegia and hyperCKemia. J Neurol Sci 2010; 300:187-90. [PMID: 20884012 DOI: 10.1016/j.jns.2010.08.065] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2010] [Revised: 07/30/2010] [Accepted: 08/27/2010] [Indexed: 11/24/2022]
Abstract
We have sequenced the entire mitochondrial DNA (mtDNA) from a 54-year-old man with chronic progressive external ophthalmoplegia (PEO) and hyperCKemia. Muscle biopsy showed ragged red and SDH positive/COX negative fibres, and the biochemistry was suggestive mitochondrial respiratory chain dysfunction. Analysis of mtDNA revealed a heteroplasmic m. 4308G>A mutation in the transfer RNA isoleucine gene (MT-TI gene). Our report expands the genetic heterogeneity of PEO.
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Affiliation(s)
- Sihem Souilem
- Department of Molecular Neurobiology and Neuropathology, La Rabta, National Institute of Neurology, Tunis, Tunisia.
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12
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Berardo A, Coku J, Kurt B, DiMauro S, Hirano M. A novel mutation in the tRNAIle gene (MTTI) affecting the variable loop in a patient with chronic progressive external ophthalmoplegia (CPEO). Neuromuscul Disord 2010; 20:204-6. [PMID: 20149659 DOI: 10.1016/j.nmd.2010.01.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2009] [Revised: 12/14/2009] [Accepted: 01/14/2010] [Indexed: 11/16/2022]
Abstract
We describe a 62-year-old woman with chronic progressive external ophthalmoplegia (CPEO), multiple lipomas, diabetes mellitus, and a novel mitochondrial DNA (mtDNA) mutation at nucleotide 4302 (4302A>G) of the tRNA(Ile) gene (MTTI). This is the first mutation at position 44 in the variable loop (V loop) of any mitochondrial tRNA. The muscle biopsy revealed 10% ragged-red/ragged-blue fibers and 25% cytochrome c oxidase (COX)-deficient fibers. No deletions or duplications were detected by Southern blot analysis. The 4302A>G transition was present only in the patient's muscle and single-fiber analysis revealed significantly higher levels of the mutation in COX-deficient than in normal fibers. Like tRNA(Leu(UUR)), tRNA(Ile) appears to be a "hot spot" for mtDNA mutations causing CPEO.
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Affiliation(s)
- Andres Berardo
- Department of Neurology, Columbia University Medical Center, New York, NY 10032, USA
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13
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Scaglia F, Wong LJC. Human mitochondrial transfer RNAs: role of pathogenic mutation in disease. Muscle Nerve 2008; 37:150-71. [PMID: 17999409 DOI: 10.1002/mus.20917] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The human mitochondrial genome encodes 13 proteins. All are subunits of the respiratory chain complexes involved in energy metabolism. These proteins are translated by a set of 22 mitochondrial transfer RNAs (tRNAs) that are required for codon reading. Human mitochondrial tRNA genes are hotspots for pathogenic mutations and have attracted interest over the last two decades with the rapid discovery of point mutations associated with a vast array of neuromuscular disorders and diverse clinical phenotypes. In this review, we use a scoring system to determine the pathogenicity of the mutations and summarize the current knowledge of structure-function relationships of these mutant tRNAs. We also provide readers with an overview of a large variety of mechanisms by which mutations may affect the mitochondrial translation machinery and cause disease.
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Affiliation(s)
- Fernando Scaglia
- Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Houston, Texas 77030, USA
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14
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Borthwick GM, Taylor RW, Walls TJ, Tonska K, Taylor GA, Shaw PJ, Ince PG, Turnbull DM. Motor neuron disease in a patient with a mitochondrial tRNAIlemutation. Ann Neurol 2006; 59:570-4. [PMID: 16358336 DOI: 10.1002/ana.20758] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
OBJECTIVE Motor neuron disease (MND) is a common neurodegenerative condition for which the underlying cause is uncertain in many patients. We identified a patient with clinical features suggestive of MND but additional cardiac and metabolic symptoms. We wished to determine if the clinical features were due to a mitochondrial DNA mutation. METHODS The brain and spinal cord were studied using neuropathological techniques and agenetic defect investigated in individual neurons. RESULTS There were atypical neuropathological features and genetic studies identified a pathogenic, heteroplasmic mitochondria tRNA(Ile) (4274T>C) mutation. INTERPRETATION This case adds to the phenotypic variation seen in mitochondrial DNA disease but also highlights the potential role of mitochondrial dysfunction in the cause of MND.
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Affiliation(s)
- Gillian M Borthwick
- Mitochondrial Research Group, School of Neurology, Neurobiology and Psychiatry, The Medical School, University of Newcastle upon Tyne, UK
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15
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Schaefer AM, Blakely EL, Griffiths PG, Turnbull DM, Taylor RW. Ophthalmoplegia due to mitochondrial DNA disease: The need for genetic diagnosis. Muscle Nerve 2005; 32:104-7. [PMID: 15795893 DOI: 10.1002/mus.20319] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
We describe a patient with chronic progressive external ophthalmoplegia (CPEO) who underwent muscle biopsy for suspected mitochondrial disease. In spite of normal histocytochemical cytochrome c oxidase (COX) activity and respiratory chain enzyme measurements in muscle, subsequent molecular genetic analysis revealed the presence of a single, large-scale deletion of mitochondrial DNA (mtDNA). The case serves to illustrate the importance of pursuing the proposed mitochondrial genetic abnormality, even in patients with normal biopsy findings.
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Affiliation(s)
- Andrew M Schaefer
- School of Neurology, Neurobiology and Psychiatry, The Medical School, Framlington Place, University of Newcastle upon Tyne, Newcastle upon Tyne NE2 4HH, United Kingdom
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16
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Tzen CY, Thajeb P, Wu TY, Chen SC. Melas with point mutations involving tRNALeu (A3243G) and tRNAGlu(A14693g). Muscle Nerve 2003; 28:575-81. [PMID: 14571459 DOI: 10.1002/mus.10473] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The syndrome of mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episode (MELAS) is typically associated with a single point mutation in the mitochondrial genome (mtDNA). Because mtDNA is known to have a higher mutation rate than nuclear DNA, we speculate that some patients with MELAS syndrome may harbor more than one mutation in mtDNA. For this purpose, mtDNA extracted from muscle containing dysmorphic mitochondria from a 32-year-old man with MELAS was sequenced in its entirety to identify all possible mutations. The result showed a homoplasmic A14693G and a heteroplasmic A3243G. The A14693G transition was not present in 205 unrelated control individuals, was not seen in 76 species randomly selected from GenBank, and appears to disrupt the base pairing within the T-loop of mtDNA tRNA(Glu). His asymptomatic siblings' blood showed wild-type at these positions, whereas the blood of the patient's oligosymptomatic diabetic mother had a heteroplasmic A14693G and an apparent homoplasmic wild-type A3243, suggesting an association of A14693G with diabetes mellitus. This case demonstrates the importance of sequencing the mtDNA in its entirety to evaluate the molecular basis of mitochondriopathy.
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Affiliation(s)
- Chin-Yuan Tzen
- Department of Pathology, Mackay Memorial Hospital, 45 Minsheng Road, Tamshui, Taipei, Taiwan.
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17
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Taylor RW, Schaefer AM, McFarland R, Maddison P, Turnbull DM. A novel mitochondrial DNA tRNA(Ile) (A4267G) mutation in a sporadic patient with mitochondrial myopathy. Neuromuscul Disord 2002; 12:659-664. [PMID: 12207935 DOI: 10.1016/s0960-8966(02)00026-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We describe a novel mutation in the mitochondrial tRNA(Ile) gene, an A to G transition at nucleotide position 4267, in a 37-year-old woman with myopathy, ataxia and sensorineural hearing loss. The A4267G mutation was heteroplasmic in several of the proband's tissues and single fibre analysis revealed significantly higher levels of mutated mitochondrial DNA in cytochrome c oxidase-deficient fibres than cytochrome c oxidase-positive fibres. It is predicted to disrupt a highly conserved base pair within the aminoacyl acceptor stem of the tRNA causing functional impairment, and as such fulfils all the accepted criteria for pathogenicity. Moreover, we were unable to detect the A4267G mutation in lymphocytes, buccal epithelia and hair of the patient's mother and two siblings, implying that the A4267G transition represents a sporadic, germline mutation.
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Affiliation(s)
- Robert W Taylor
- Department of Neurology, The Medical School, University of Newcastle upon Tyne, Framlington Place, NE2 4HH, Newcastle upon Tyne, UK.
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18
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Chapter 3 Molecular Genetic Basis of the Mitochondrial Encephalomyopathies. ACTA ACUST UNITED AC 2002. [DOI: 10.1016/s1877-3419(09)70062-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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19
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Corona P, Lamantea E, Greco M, Carrara F, Agostino A, Guidetti D, Dotti MT, Mariotti C, Zeviani M. Novel heteroplasmic mtDNA mutation in a family with heterogeneous clinical presentations. Ann Neurol 2002; 51:118-22. [PMID: 11782991 DOI: 10.1002/ana.10059] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The protean manifestations of a novel maternally inherited point mutation of the mitochondrial genome are reported. The proband showed isolated, spastic paraparesis. A brother, who had suffered from a multisystem progressive disorder, ultimately died of cardiomyopathy. Another brother is healthy. The proband's mother showed truncal ataxia, dysarthria, severe hearing loss, mental regression, ptosis, ophthalmoparesis, distal cyclones, and diabetes mellitus. A muscle biopsy performed in the proband failed to show the morphological abnormalities typical of mitochondrial disorders; the activities of respiratory chain complexes were normal. However, complex I and IV activities were low in the muscle homogenate of the affected mother and brother. Sequence analysis of mtDNA showed a heteroplasmic mutation of the tRNA(Ile) gene (G4284A). The mutation load was approximately 55%, 80%, and 90% in the muscle mtDNA of the proband, his mother, and his affected brother, respectively. Mutation was undetected in the healthy brother, as well as in 100 control samples. Several cybrid clones containing homoplasmic mutant mtDNA from the proband showed significant reductions of complex IV activity and maximum oxygen consumption rate, compared with homoplasmic wild-type clones derived from the same subject.
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Affiliation(s)
- P Corona
- Division of Biochemistry and Genetics, National Neurological Institute C. Besta, Milan, Italy
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20
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Abstract
The mitochondrial encephalomyopathies are a genetically heterogeneous group of disorders associated with impaired oxidative phosphorylation. Patients may exhibit a wide range of clinical symptoms and experience significant morbidity and mortality. There is currently no curative treatment. At present the majority of genetically defined mitochondrial encephalomyopathies are caused by mutations in mitochondrial DNA. The underlying molecular mechanisms and the complex relationship between genotype and phenotype in these mitochondrial DNA diseases remain only partially understood. We describe the key features of mitochondrial DNA genetics and outline some of the common disease phenotypes associated with mtDNA defects. A classification of pathogenic mitochondrial DNA point mutations which may have therapeutic implications is outlined.
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Affiliation(s)
- T Pulkes
- Muscle and Neurogenetics Sections, University Department of Clinical Neurology, Institute of Neurology, University College London, Queen Square, WC1N 3BG, London, UK
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21
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Kelley SO, Steinberg SV, Schimmel P. Fragile T-stem in disease-associated human mitochondrial tRNA sensitizes structure to local and distant mutations. J Biol Chem 2001; 276:10607-11. [PMID: 11110797 DOI: 10.1074/jbc.m008320200] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mutations in human mitochondrial isoleucine tRNA (hs mt tRNA(Ile)) are associated with cardiomyopathy and opthalmoplegia. A recent study showed that opthalmoplegia-related mutations gave rise to severe decreases in aminoacylation efficiencies and that the defective mutant tRNAs were effective inhibitors of aminoacylation of the wild-type substrate. The results suggested that the effectiveness of the mutations was due in large part to an inherently fragile mitochondrial tRNA structure. Here, we investigate mutant tRNAs associated with cardiomyopathy, and a series of rationally designed second-site substitutions introduced into both opthalmoplegia- and cardiomyopathy-related mutant tRNAs. A source of structural fragility was uncovered. An inherently unstable T-stem appears susceptible to misalignments. This susceptibility sensitizes both domains of the L-shaped tRNA structure to base substitutions that are deleterious. Thus, the fragile T-stem makes the structure of this human mitochondrial tRNA particularly vulnerable to local and distant mutations.
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Affiliation(s)
- S O Kelley
- Skaggs Institute for Chemical Biology, The Scripps Research Institute, Beckman Center, La Jolla, California 92037, USA.
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22
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Abstract
Mitochondrial diseases are a heterogeneous group of disorders with widely varying clinical features, due to defects in mitochondrial function. Involvement of both muscle and nerve is common in mitochondrial disease. In some cases, this involvement is subclinical or a minor part of a multisystem disorder, but myopathy and neuropathy are a major, often presenting, feature of a number of mitochondrial syndromes. In addition, mitochondrial dysfunction may play a role in a number of classic neuromuscular diseases. This article reviews the role of mitochondrial dysfunction in neuromuscular disease and discusses a rational approach to diagnosis and treatment of patients presenting with a neuromuscular syndrome due to mitochondrial disease.
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Affiliation(s)
- R A Nardin
- Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, Harvard Institute of Medicine, Rm 858, 77 Avenue Louis Pasteur, Boston, Massachusetts 02115, USA
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23
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Morgan-Hughes JA, Hanna MG. Mitochondrial encephalomyopathies: the enigma of genotype versus phenotype. BIOCHIMICA ET BIOPHYSICA ACTA 1999; 1410:125-45. [PMID: 10076022 DOI: 10.1016/s0005-2728(98)00162-5] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Over the past decade a large body of evidence has accumulated implicating defects of human mitochondrial DNA in the pathogenesis of a group of disorders known collectively as the mitochondrial encephalomyopathies. Although impaired oxidative phosphorylation is likely to represent the final common pathway leading to cellular dysfunction in these diseases, fundamental issues still remain elusive. Perhaps the most challenging of these is to understand the mechanisms which underlie the complex relationship between genotype and phenotype. Here we examine this relationship and discuss some of the factors which are likely to be involved.
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Affiliation(s)
- J A Morgan-Hughes
- University Department of Clinical Neurology, Institute of Neurology, Queen Square, London WC1H 3BG, UK
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24
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Howell N. Human mitochondrial diseases: answering questions and questioning answers. INTERNATIONAL REVIEW OF CYTOLOGY 1998; 186:49-116. [PMID: 9770297 DOI: 10.1016/s0074-7696(08)61051-7] [Citation(s) in RCA: 84] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Since the first identification in 1988 of pathogenic mitochondrial DNA (mtDNA) mutations, the mitochondrial diseases have emerged as a major clinical entity. The most striking feature of these disorders is their marked heterogeneity, which extends to their clinical, biochemical, and genetic characteristics. The major mitochondrial encephalomyopathies include MELAS (mitochondrial encephalopathy with lactic acidosis and stroke-like episodes), MERRF (myoclonic epilepsy with ragged red fibers), KSS/CPEO (Kearns-Sayre syndrome/chronic progressive external ophthalmoplegia), and NARP/MILS (neuropathy, ataxia, and retinitis pigmentosum/maternally inherited Leigh syndrome) and they typically present highly variable multisystem defects that usually involve abnormalities of skeletal muscle and/or the CNS. The primary emphasis here is to review recent investigations of these mitochondrial diseases from the standpoint of how the complexities of mitochondrial genetics and biogenesis might determine their varied features. In addition, the mitochondrial encephalomyopathies are compared and contrasted to Leber hereditary optic neuropathy, a mitochondrial disease in which the pathogenic mtDNA mutations produce a more uniform and focal neuropathology. All of these disorders involve, at some level, a mitochondrial respiratory chain dysfunction. Because mitochondrial genetics differs so strikingly from the Mendelian inheritance of chromosomes, recent research on the origin and subsequent segregation and transmission of mtDNA mutations is reviewed.
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Affiliation(s)
- N Howell
- Department of Radiation Oncology, University of Texas Medical Branch, Galveston 77555, USA.
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25
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Abstract
It is nearly a decade since the discovery of the first mutations in mitochondrial DNA associated with mitochondrial encephalomyopathy, and the pace of discovery of new mitochondrial DNA mutations continues unabated. Nuclear gene defects in these disorders have been more difficult to identify; only one is known, but others have been mapped by linkage analysis. The rules governing transmission and segregation of mitochondrial DNA sequence variants are beginning to be unravelled and progress has been made in understanding genotype-phenotype relationships and elucidating mechanisms of pathogenesis.
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26
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Taylor RW, Chinnery PF, Bates MJ, Jackson MJ, Johnson MA, Andrews RM, Turnbull DM. A novel mitochondrial DNA point mutation in the tRNA(Ile) gene: studies in a patient presenting with chronic progressive external ophthalmoplegia and multiple sclerosis. Biochem Biophys Res Commun 1998; 243:47-51. [PMID: 9473477 DOI: 10.1006/bbrc.1997.8055] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
We report a new mutation, a G to A transition at nucleotide position 4298 within the mitochondrial tRNA(Ile) gene in a patient with chronic progressive external ophthalmoplegia and multiple sclerosis. The mutation, which alters an evolutionary conserved nucleotide within the anticodon stem, was heteroplasmic in skeletal muscle but was not present in the patient's blood. Single fibre PCR analysis revealed significantly higher levels of the G4298A mutation in cytochrome c oxidase (COX) negative fibres than in COX-positive fibres. This mutation represents the seventh pathogenic nucleotide substitution to be found in this gene and as such confirms the tRNA(Ile) gene as a susceptible "hot spot" for mitochondrial DNA point mutations. Of particular interest is that this patient has the clinical features of both multiple sclerosis and a mitochondrial DNA disorder.
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MESH Headings
- Animals
- Base Sequence
- DNA, Mitochondrial/chemistry
- DNA, Mitochondrial/genetics
- Electron Transport Complex IV/metabolism
- Female
- Humans
- Middle Aged
- Mitochondrial Myopathies/complications
- Mitochondrial Myopathies/genetics
- Mitochondrial Myopathies/metabolism
- Molecular Sequence Data
- Multiple Sclerosis/complications
- Multiple Sclerosis/genetics
- Multiple Sclerosis/metabolism
- Muscle Fibers, Skeletal/metabolism
- Muscle, Skeletal/metabolism
- Nucleic Acid Conformation
- Ophthalmoplegia, Chronic Progressive External/complications
- Ophthalmoplegia, Chronic Progressive External/genetics
- Ophthalmoplegia, Chronic Progressive External/metabolism
- Point Mutation
- RNA, Transfer, Ile/genetics
- Sequence Homology, Nucleic Acid
- Species Specificity
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Affiliation(s)
- R W Taylor
- Department of Neurology, Medical School, University of Newcastle upon Tyne, United Kingdom
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