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Gunawardena K, Praveenan S, Dissanayake VHW, Ratnayake P. Mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes with coexisting nemaline myopathy: a case report. J Med Case Rep 2024; 18:420. [PMID: 39252049 PMCID: PMC11385988 DOI: 10.1186/s13256-024-04723-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Accepted: 07/25/2024] [Indexed: 09/11/2024] Open
Abstract
BACKGROUND Mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes and nemaline myopathy are two rare genetic conditions. We report the first case reported in world literature with coexistence of both these rare disorders. CASE PRESENTATION A 11-year-old previously healthy Sri Lankan male child, product of a nonconsanguineous marriage with normal development presented with acute onset short lasting recurring episodes of right-sided eye deviation with impaired consciousness. In between episodes he regained consciousness. Family history revealed a similar presentation in the mother at 36 years of age. Examination was significant for short stature and proximal upper and lower limb weakness. His plasma and cerebrospinal fluid lactate were elevated. Magnetic resonance imaging brain had evidence of an acute infarction in the right occipital territory. Sanger sequencing for common mitochondrial variants of mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes confirmed this diagnosis. Whole exome sequencing revealed pathogenic compound heterozygous variants in NEB gene implicating in coexisting nemaline myopathy. Acute presentation was managed with supportive care, antiepileptics, and mitochondrial supplementation. Currently he is stable on daily supplementation of arginine and limb-strengthening physiotherapy. He is being monitored closely clinically and with serum lactate level. CONCLUSION Genetic diseases are rare. Coexistence of two genetic conditions is even rarer. Genetic confirmation of diagnosis is imperative for prediction of complications, accurate management, and genetic counseling.
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Affiliation(s)
- Kawmadi Gunawardena
- Pediatric Neurology Department, Lady Ridgeway Hospital for Children, Colombo 08, Sri Lanka.
- Department of Anatomy, Genetics and Bioinformatics, Faculty of Medicine, University of Colombo, Colombo 08, Sri Lanka.
| | - Somasundaram Praveenan
- Department of Anatomy, Genetics and Bioinformatics, Faculty of Medicine, University of Colombo, Colombo 08, Sri Lanka
| | - Vajira H W Dissanayake
- Department of Anatomy, Genetics and Bioinformatics, Faculty of Medicine, University of Colombo, Colombo 08, Sri Lanka
| | - Pyara Ratnayake
- Pediatric Neurology Department, Lady Ridgeway Hospital for Children, Colombo 08, Sri Lanka
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Fan HC, Lee HF, Yue CT, Chi CS. Clinical Characteristics of Mitochondrial Encephalomyopathy, Lactic Acidosis, and Stroke-Like Episodes. Life (Basel) 2021; 11:life11111111. [PMID: 34832987 PMCID: PMC8617702 DOI: 10.3390/life11111111] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Revised: 10/11/2021] [Accepted: 10/16/2021] [Indexed: 12/12/2022] Open
Abstract
Mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS) syndrome, a maternally inherited mitochondrial disorder, is characterized by its genetic, biochemical and clinical complexity. The most common mutation associated with MELAS syndrome is the mtDNA A3243G mutation in the MT-TL1 gene encoding the mitochondrial tRNA-leu(UUR), which results in impaired mitochondrial translation and protein synthesis involving the mitochondrial electron transport chain complex subunits, leading to impaired mitochondrial energy production. Angiopathy, either alone or in combination with nitric oxide (NO) deficiency, further contributes to multi-organ involvement in MELAS syndrome. Management for MELAS syndrome is amostly symptomatic multidisciplinary approach. In this article, we review the clinical presentations, pathogenic mechanisms and options for management of MELAS syndrome.
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Affiliation(s)
- Hueng-Chuen Fan
- Department of Pediatrics, Tungs’ Taichung Metroharbor Hospital, Wuchi, Taichung 435, Taiwan; (H.-C.F.); (C.-T.Y.)
- Department of Medical Research, Tungs’ Taichung Metroharbor Hospital, Wuchi, Taichung 435, Taiwan
- Department of Rehabilitation, Jen-Teh Junior College of Medicine, Nursing and Management, Miaoli 356, Taiwan
- Department of Life Sciences, Agricultural Biotechnology Center, National Chung Hsing University, Taichung 402, Taiwan
| | - Hsiu-Fen Lee
- Department of Pediatrics, Taichung Veterans General Hospital, Taichung 407, Taiwan;
| | - Chen-Tang Yue
- Department of Pediatrics, Tungs’ Taichung Metroharbor Hospital, Wuchi, Taichung 435, Taiwan; (H.-C.F.); (C.-T.Y.)
| | - Ching-Shiang Chi
- Department of Pediatrics, Tungs’ Taichung Metroharbor Hospital, Wuchi, Taichung 435, Taiwan; (H.-C.F.); (C.-T.Y.)
- Correspondence: ; Tel.: +886-4-26581919-4301
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La Morgia C, Maresca A, Caporali L, Valentino ML, Carelli V. Mitochondrial diseases in adults. J Intern Med 2020; 287:592-608. [PMID: 32463135 DOI: 10.1111/joim.13064] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Revised: 02/07/2020] [Accepted: 02/21/2020] [Indexed: 02/07/2023]
Abstract
Mitochondrial medicine is a field that expanded exponentially in the last 30 years. Individually rare, mitochondrial diseases as a whole are probably the most frequent genetic disorder in adults. The complexity of their genotype-phenotype correlation, in terms of penetrance and clinical expressivity, natural history and diagnostic algorithm derives from the dual genetic determination. In fact, in addition to the about 1.500 genes encoding mitochondrial proteins that reside in the nuclear genome (nDNA), we have the 13 proteins encoded by the mitochondrial genome (mtDNA), for which 22 specific tRNAs and 2 rRNAs are also needed. Thus, besides Mendelian genetics, we need to consider all peculiarities of how mtDNA is inherited, maintained and expressed to fully understand the pathogenic mechanisms of these disorders. Yet, from the initial restriction to the narrow field of oxidative phosphorylation dysfunction, the landscape of mitochondrial functions impinging on cellular homeostasis, driving life and death, is impressively enlarged. Finally, from the clinical standpoint, starting from the neuromuscular field, where brain and skeletal muscle were the primary targets of mitochondrial dysfunction as energy-dependent tissues, after three decades virtually any subspecialty of medicine is now involved. We will summarize the key clinical pictures and pathogenic mechanisms of mitochondrial diseases in adults.
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Affiliation(s)
- C La Morgia
- From the, Dipartimento di Scienze Biomediche e Neuromotorie, Università di Bologna, Bologna, Italy.,IRCCS Istituto delle Scienze Neurologiche di Bologna, UOC Clinica Neurologica, Bologna, Italy
| | - A Maresca
- IRCCS Istituto delle Scienze Neurologiche di Bologna, UOC Clinica Neurologica, Bologna, Italy
| | - L Caporali
- IRCCS Istituto delle Scienze Neurologiche di Bologna, UOC Clinica Neurologica, Bologna, Italy
| | - M L Valentino
- From the, Dipartimento di Scienze Biomediche e Neuromotorie, Università di Bologna, Bologna, Italy.,IRCCS Istituto delle Scienze Neurologiche di Bologna, UOC Clinica Neurologica, Bologna, Italy
| | - V Carelli
- From the, Dipartimento di Scienze Biomediche e Neuromotorie, Università di Bologna, Bologna, Italy.,IRCCS Istituto delle Scienze Neurologiche di Bologna, UOC Clinica Neurologica, Bologna, Italy
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Abstract
Mitochondria play various important roles in energy production, metabolism, and apoptosis. Mitochondrial dysfunction caused by alterations in mitochondrial DNA (mtDNA) can lead to the initiation and progression of cancers and other diseases. These alterations include mutations and copy number variations. Especially, the mutations in D-loop, MT-ND1, and MT-ND5 affect mitochondrial functions and are widely detected in various cancers. Meanwhile, several other mutations have been correlated with muscular and neuronal diseases, especially MT-TL1 is deeply related. These pieces of evidence indicated mtDNA alterations in diseases show potential as a novel therapeutic target. mtDNA repair enzymes are the target for delaying or stalling the mtDNA damage-induced cancer progression and metastasis. Moreover, some mutations reveal a prognosis ability of the drug resistance. Current efforts aim to develop mitochondrial transplantation technique as a direct cure for deregulated mitochondria-associated diseases. This review summarizes the implications of mitochondrial dysfunction in cancers and other pathologies; and discusses the relevance of mitochondria-targeted therapies, along with their contribution as potential biomarkers.
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Affiliation(s)
- Ngoc Ngo Yen Nguyen
- Department of Biomedical Science, Graduate School, Kyung Hee University, Seoul, Republic of Korea.,Biomedical Science Institute, Kyung Hee University, Seoul, Republic of Korea
| | - Sung Soo Kim
- Biomedical Science Institute, Kyung Hee University, Seoul, Republic of Korea.,Department of Biochemistry and Molecular Biology, School of Medicine, Kyung Hee University, Seoul, Republic of Korea
| | - Yong Hwa Jo
- Biomedical Science Institute, Kyung Hee University, Seoul, Republic of Korea.,Department of Biochemistry and Molecular Biology, School of Medicine, Kyung Hee University, Seoul, Republic of Korea
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Abstract
BACKGROUND Given the etiologic heterogeneity of disease classification using clinical phenomenology, we employed contemporary criteria to classify variants associated with myoclonic epilepsy with ragged-red fibers (MERRF) syndrome and to assess the strength of evidence of gene-disease associations. Standardized approaches are used to clarify the definition of MERRF, which is essential for patient diagnosis, patient classification, and clinical trial design. METHODS Systematic literature and database search with application of standardized assessment of gene-disease relationships using modified Smith criteria and of variants reported to be associated with MERRF using modified Yarham criteria. RESULTS Review of available evidence supports a gene-disease association for two MT-tRNAs and for POLG. Using modified Smith criteria, definitive evidence of a MERRF gene-disease association is identified for MT-TK. Strong gene-disease evidence is present for MT-TL1 and POLG. Functional assays that directly associate variants with oxidative phosphorylation impairment were critical to mtDNA variant classification. In silico analysis was of limited utility to the assessment of individual MT-tRNA variants. With the use of contemporary classification criteria, several mtDNA variants previously reported as pathogenic or possibly pathogenic are reclassified as neutral variants. CONCLUSIONS MERRF is primarily an MT-TK disease, with pathogenic variants in this gene accounting for ~90% of MERRF patients. Although MERRF is phenotypically and genotypically heterogeneous, myoclonic epilepsy is the clinical feature that distinguishes MERRF from other categories of mitochondrial disorders. Given its low frequency in mitochondrial disorders, myoclonic epilepsy is not explained simply by an impairment of cellular energetics. Although MERRF phenocopies can occur in other genes, additional data are needed to establish a MERRF disease-gene association. This approach to MERRF emphasizes standardized classification rather than clinical phenomenology, thus improving patient diagnosis and clinical trial design.
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Xia CY, Liu Y, Liu H, Zhang YC, Ma YN, Qi Y. Clinical and Molecular Characteristics in 100 Chinese Pediatric Patients with m.3243A>G Mutation in Mitochondrial DNA. Chin Med J (Engl) 2017; 129:1945-9. [PMID: 27503020 PMCID: PMC4989426 DOI: 10.4103/0366-6999.187845] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Background: Mitochondrial diseases are a group of energy metabolic disorders with multisystem involvements. Variable clinical features present a major challenge in pediatric diagnoses. We summarized the clinical spectrum of m.3243A>G mutation in Chinese pediatric patients, to define the common clinical manifestations and study the correlation between heteroplasmic degree of the mutation and clinical severity of the disease. Methods: Clinical data of one-hundred pediatric patients with symptomatic mitochondrial disease harboring m.3243A>G mutation from 2007 to 2013 were retrospectively reviewed. Detection of m.3243A>G mutation ratio was performed by polymerase chain reaction (PCR)-restriction fragment length polymorphism. Correlation between m.3243A>G mutation ratio and age was evaluated. The differences in clinical symptom frequency of patients with low, middle, and high levels of mutation ratio were analyzed by Chi-square test. Results: Sixty-six patients (66%) had suffered a delayed diagnosis for an average of 2 years. The most frequent symptoms were seizures (76%), short stature (73%), elevated plasma lactate (70%), abnormal magnetic resonance imaging/computed tomography (MRI/CT) changes (68%), vomiting (55%), decreased vision (52%), headache (50%), and muscle weakness (48%). The mutation ratio was correlated negatively with onset age (r = −0.470, P < 0.001). Myopathy was more frequent in patients with a high level of mutation ratio. However, patients with a low or middle level of m.3243A>G mutation ratio were more likely to suffer hearing loss, decreased vision, and gastrointestinal disturbance than patients with a high level of mutation ratio. Conclusions: Our study showed that half of Chinese pediatric patients with m.3243A>G mutation presented seizures, short stature, abnormal MRI/CT changes, elevated plasma lactate, vomiting, and headache. Pediatric patients with these recurrent symptoms should be considered for screening m.3243A>G mutation. Clinical manifestations and laboratory abnormalities should be carefully monitored in patients with this point mutation.
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Affiliation(s)
- Chang-Yu Xia
- Department of Central Laboratory, Peking University First Hospital, Beijing 100034, China
| | - Yu Liu
- Department of Central Laboratory, Peking University First Hospital, Beijing 100034, China
| | - Hui Liu
- Department of Central Laboratory, Peking University First Hospital, Beijing 100034, China
| | - Yan-Chun Zhang
- Department of Central Laboratory, Peking University First Hospital, Beijing 100034, China
| | - Yi-Nan Ma
- Department of Central Laboratory, Peking University First Hospital, Beijing 100034, China
| | - Yu Qi
- Department of Central Laboratory, Peking University First Hospital, Beijing 100034, China
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7
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Ghaloul-Gonzalez L, Goldstein A, Walsh Vockley C, Dobrowolski SF, Biery A, Irani A, Ibarra J, Morton DH, Mohsen AW, Vockley J. Mitochondrial respiratory chain disorders in the Old Order Amish population. Mol Genet Metab 2016; 118:296-303. [PMID: 27344355 DOI: 10.1016/j.ymgme.2016.06.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Revised: 06/06/2016] [Accepted: 06/06/2016] [Indexed: 12/20/2022]
Abstract
The Old Order Amish populations in the US are one of the Plain People groups and are descendants of the Swiss Anabaptist immigrants who came to North America in the early eighteenth century. They live in numerous small endogamous demes that have resulted in reduced genetic diversity along with a high prevalence of specific genetic disorders, many of them autosomal recessive. Mitochondrial respiratory chain deficiencies arising from mitochondrial or nuclear DNA mutations have not previously been reported in the Plain populations. Here we present four different Amish families with mitochondrial respiratory chain disorders. Mutations in two mitochondrial encoded genes leading to mitochondrial respiratory chain disorder were identified in two patients. In the first case, MELAS syndrome caused by a mitochondrial DNA (mtDNA) mutation (m.3243A>G) was identified in an extended Amish pedigree following a presentation of metabolic strokes in the proband. Characterization of the extended family of the proband by a high resolution melting assay identified the same mutation in many previously undiagnosed family members with a wide range of clinical symptoms. A MELAS/Leigh syndrome phenotype caused by a mtDNA mutation [m.13513G>A; p.Asp393Asn] in the ND5 gene encoding the ND5 subunit of respiratory chain complex I was identified in a patient in a second family. Mutations in two nuclear encoded genes leading to mitochondrial respiratory chain disorder were also identified in two patients. One patient presented with Leigh syndrome and had a homozygous deletion in the NDUFAF2 gene, while the second patient had a homozygous mutation in the POLG gene, [c.1399G>A; p.Ala467Thr]. Our findings identify mitochondrial respiratory chain deficiency as a cause of disease in the Old Order Amish that must be considered in the context of otherwise unexplained systemic disease, especially if neuromuscular symptoms are present.
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Affiliation(s)
- Lina Ghaloul-Gonzalez
- Department of Pediatrics, School of Medicine, University of Pittsburgh, Children's Hospital of Pittsburgh of UPMC, Pittsburgh, PA, USA.
| | - Amy Goldstein
- Department of Pediatrics, School of Medicine, University of Pittsburgh, Children's Hospital of Pittsburgh of UPMC, Pittsburgh, PA, USA
| | - Catherine Walsh Vockley
- Department of Pediatrics, School of Medicine, University of Pittsburgh, Children's Hospital of Pittsburgh of UPMC, Pittsburgh, PA, USA
| | - Steven F Dobrowolski
- Department of Pathology, School of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
| | - Amy Biery
- Department of Human Genetics, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA, USA
| | - Afifa Irani
- Department of Human Genetics, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA, USA
| | - Jordan Ibarra
- University of Pittsburgh, School of Medicine, Pittsburgh, PA, USA
| | - D Holmes Morton
- Central Pennsylvania Clinic, A Medical Home for Special Children and Adults, Belleville, PA, USA
| | - Al-Walid Mohsen
- Department of Pediatrics, School of Medicine, University of Pittsburgh, Children's Hospital of Pittsburgh of UPMC, Pittsburgh, PA, USA
| | - Jerry Vockley
- Department of Pediatrics, School of Medicine, University of Pittsburgh, Children's Hospital of Pittsburgh of UPMC, Pittsburgh, PA, USA; Department of Human Genetics, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA, USA
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8
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Suzuki H, Ono M, Kojima Y, Kanda M, Shibasaki H, Oki M, Nakano S. [A case of MELAS associated with histochemical findings of muscles characteristic of MERRF]. Rinsho Shinkeigaku 2016; 56:196-199. [PMID: 26960269 DOI: 10.5692/clinicalneurol.cn-000783] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We here report a 39-year-old woman of short stature with sensorineural deafness, who suddenly developed status epilepticus. T2-weighed image of brain magnetic resonance imaging (MRI) revealed a high signal lesion in the left temporal area, the distribution of which was not compatible with any particular arterial supply. Lactate and pyruvate were elevated in the serum and cerebrospinal fluid. As the mitochondrial gene analysis revealed the m.3243A>G mutation, diagnosis of mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episode (MELAS) was made. In the histochemical study of a biopsied muscle, the intramuscular blood vessels reacted strongly with SDH (SSV), but the SSV was negative for cytochrome c oxidase (COX), the findings characteristic of myoclonic epilepsy with ragged-red fibers (MERRF). This is the first case of MELAS in which the muscle histochemistry showed positive SSV unassociated with increased COX.
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9
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Wilson IJ, Carling PJ, Alston CL, Floros VI, Pyle A, Hudson G, Sallevelt SCEH, Lamperti C, Carelli V, Bindoff LA, Samuels DC, Wonnapinij P, Zeviani M, Taylor RW, Smeets HJM, Horvath R, Chinnery PF. Mitochondrial DNA sequence characteristics modulate the size of the genetic bottleneck. Hum Mol Genet 2016; 25:1031-41. [PMID: 26740552 PMCID: PMC4754047 DOI: 10.1093/hmg/ddv626] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2015] [Accepted: 12/22/2015] [Indexed: 01/03/2023] Open
Abstract
With a combined carrier frequency of 1:200, heteroplasmic mitochondrial DNA (mtDNA) mutations cause human disease in ∼1:5000 of the population. Rapid shifts in the level of heteroplasmy seen within a single generation contribute to the wide range in the severity of clinical phenotypes seen in families transmitting mtDNA disease, consistent with a genetic bottleneck during transmission. Although preliminary evidence from human pedigrees points towards a random drift process underlying the shifting heteroplasmy, some reports describe differences in segregation pattern between different mtDNA mutations. However, based on limited observations and with no direct comparisons, it is not clear whether these observations simply reflect pedigree ascertainment and publication bias. To address this issue, we studied 577 mother–child pairs transmitting the m.11778G>A, m.3460G>A, m.8344A>G, m.8993T>G/C and m.3243A>G mtDNA mutations. Our analysis controlled for inter-assay differences, inter-laboratory variation and ascertainment bias. We found no evidence of selection during transmission but show that different mtDNA mutations segregate at different rates in human pedigrees. m.8993T>G/C segregated significantly faster than m.11778G>A, m.8344A>G and m.3243A>G, consistent with a tighter mtDNA genetic bottleneck in m.8993T>G/C pedigrees. Our observations support the existence of different genetic bottlenecks primarily determined by the underlying mtDNA mutation, explaining the different inheritance patterns observed in human pedigrees transmitting pathogenic mtDNA mutations.
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Affiliation(s)
| | - Phillipa J Carling
- Institute of Genetic Medicine, Wellcome Trust Centre for Mitochondrial Research and
| | - Charlotte L Alston
- Wellcome Trust Centre for Mitochondrial Research and Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK
| | - Vasileios I Floros
- Medical Research Council Mitochondrial Biology Unit, Cambridge, UK, Department of Clinical Neurosciences, School of Clinical Medicine, University of Cambridge, Cambridge, UK
| | - Angela Pyle
- Institute of Genetic Medicine, Wellcome Trust Centre for Mitochondrial Research and
| | - Gavin Hudson
- Institute of Genetic Medicine, Wellcome Trust Centre for Mitochondrial Research and
| | - Suzanne C E H Sallevelt
- Department of Clinical Genetics, Research Schools GROW/CARIM, Maastricht University Medical Center, Maastricht, Netherlands
| | - Costanza Lamperti
- Division of Molecular Neurogenetics, National Neurological Institute 'C. Besta', Milano, Italy
| | - Valerio Carelli
- IRCCS Institute of Neurological Sciences of Bologna, Bellaria Hospital, Bologna, Italy, Unit of Neurology, Department of Biomedical and NeuroMotor Sciences (DIBINEM), University of Bologna, Bologna, Italy
| | - Laurence A Bindoff
- Department of Neurology, Haukeland University Hospital, Bergen, Norway, Department of Clinical Medicine (K1), University of Bergen, Bergen, Norway
| | - David C Samuels
- Vanderbilt Genetics Institute, Department of Molecular Physiology and Biophysics, Vanderbilt School of Medicine, Nashville, TN, USA and
| | - Passorn Wonnapinij
- Department of Genetics, Faculty of Science, Kasetsart University, Bangkok, Thailand
| | - Massimo Zeviani
- Medical Research Council Mitochondrial Biology Unit, Cambridge, UK, Division of Molecular Neurogenetics, National Neurological Institute 'C. Besta', Milano, Italy
| | - Robert W Taylor
- Wellcome Trust Centre for Mitochondrial Research and Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK
| | - Hubert J M Smeets
- Department of Clinical Genetics, Research Schools GROW/CARIM, Maastricht University Medical Center, Maastricht, Netherlands
| | - Rita Horvath
- Institute of Genetic Medicine, Wellcome Trust Centre for Mitochondrial Research and
| | - Patrick F Chinnery
- Wellcome Trust Centre for Mitochondrial Research and Medical Research Council Mitochondrial Biology Unit, Cambridge, UK, Department of Clinical Neurosciences, School of Clinical Medicine, University of Cambridge, Cambridge, UK,
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El-Hattab AW, Adesina AM, Jones J, Scaglia F. MELAS syndrome: Clinical manifestations, pathogenesis, and treatment options. Mol Genet Metab 2015; 116:4-12. [PMID: 26095523 DOI: 10.1016/j.ymgme.2015.06.004] [Citation(s) in RCA: 352] [Impact Index Per Article: 39.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/13/2015] [Revised: 06/14/2015] [Accepted: 06/14/2015] [Indexed: 12/13/2022]
Abstract
Mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS) syndrome is one of the most frequent maternally inherited mitochondrial disorders. MELAS syndrome is a multi-organ disease with broad manifestations including stroke-like episodes, dementia, epilepsy, lactic acidemia, myopathy, recurrent headaches, hearing impairment, diabetes, and short stature. The most common mutation associated with MELAS syndrome is the m.3243A>G mutation in the MT-TL1 gene encoding the mitochondrial tRNA(Leu(UUR)). The m.3243A>G mutation results in impaired mitochondrial translation and protein synthesis including the mitochondrial electron transport chain complex subunits leading to impaired mitochondrial energy production. The inability of dysfunctional mitochondria to generate sufficient energy to meet the needs of various organs results in the multi-organ dysfunction observed in MELAS syndrome. Energy deficiency can also stimulate mitochondrial proliferation in the smooth muscle and endothelial cells of small blood vessels leading to angiopathy and impaired blood perfusion in the microvasculature of several organs. These events will contribute to the complications observed in MELAS syndrome particularly the stroke-like episodes. In addition, nitric oxide deficiency occurs in MELAS syndrome and can contribute to its complications. There is no specific consensus approach for treating MELAS syndrome. Management is largely symptomatic and should involve a multidisciplinary team. Unblinded studies showed that l-arginine therapy improves stroke-like episode symptoms and decreases the frequency and severity of these episodes. Additionally, carnitine and coenzyme Q10 are commonly used in MELAS syndrome without proven efficacy.
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Affiliation(s)
- Ayman W El-Hattab
- Division of Clinical Genetics and Metabolic Disorders, Department of Pediatrics, Tawam Hospital, Al-Ain, United Arab Emirates
| | - Adekunle M Adesina
- Department of Pathology and Immunology, Baylor College of Medicine, Houston, TX, USA
| | - Jeremy Jones
- Singleton Department of Radiology, Texas Children's Hospital, Houston, TX, USA
| | - Fernando Scaglia
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA.
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Chin J, Marotta R, Chiotis M, Allan E, Collins S. Detection rates and phenotypic spectrum of m.3243A>G in the MT-TL1 gene: A molecular diagnostic laboratory perspective. Mitochondrion 2014; 17:34-41. [DOI: 10.1016/j.mito.2014.05.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2013] [Revised: 05/01/2014] [Accepted: 05/13/2014] [Indexed: 10/25/2022]
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12
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Rubegni A, Cardaioli E, Chini E, Da Pozzo P, Battisti C, Malandrini A, Federico A. A case of 3243A>G mutation in mtDNA presenting as apparently idiopathic hyperCKemia. J Neurol Sci 2014; 338:232-4. [DOI: 10.1016/j.jns.2014.01.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2013] [Revised: 12/14/2013] [Accepted: 01/06/2014] [Indexed: 10/25/2022]
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13
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Yeung KY, Dickinson A, Donoghue JF, Polekhina G, White SJ, Grammatopoulos DK, McKenzie M, Johns TG, John JCS. The identification of mitochondrial DNA variants in glioblastoma multiforme. Acta Neuropathol Commun 2014; 2:1. [PMID: 24383468 PMCID: PMC3912901 DOI: 10.1186/2051-5960-2-1] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2013] [Accepted: 12/07/2013] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND Mitochondrial DNA (mtDNA) encodes key proteins of the electron transfer chain (ETC), which produces ATP through oxidative phosphorylation (OXPHOS) and is essential for cells to perform specialised functions. Tumor-initiating cells use aerobic glycolysis, a combination of glycolysis and low levels of OXPHOS, to promote rapid cell proliferation and tumor growth. Glioblastoma multiforme (GBM) is an aggressively malignant brain tumor and mitochondria have been proposed to play a vital role in GBM tumorigenesis. RESULTS Using next generation sequencing and high resolution melt analysis, we identified a large number of mtDNA variants within coding and non-coding regions of GBM cell lines and predicted their disease-causing potential through in silico modeling. The frequency of variants was greatest in the D-loop and origin of light strand replication in non-coding regions. ND6 was the most susceptible coding gene to mutation whilst ND4 had the highest frequency of mutation. Both genes encode subunits of complex I of the ETC. These variants were not detected in unaffected brain samples and many have not been previously reported. Depletion of HSR-GBM1 cells to varying degrees of their mtDNA followed by transplantation into immunedeficient mice resulted in the repopulation of the same variants during tumorigenesis. Likewise, de novo variants identified in other GBM cell lines were also incorporated. Nevertheless, ND4 and ND6 were still the most affected genes. We confirmed the presence of these variants in high grade gliomas. CONCLUSIONS These novel variants contribute to GBM by rendering the ETC. partially dysfunctional. This restricts metabolism to anaerobic glycolysis and promotes cell proliferation.
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14
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Harihara S, Nakamura K, Takubo K, Takeuchi F. Spontaneous event of mitochondrial DNA mutation, A3243G, found in a family of identical twins. ACTA ACUST UNITED AC 2012; 24:158-62. [PMID: 23072508 DOI: 10.3109/19401736.2012.731402] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
A mutation in mitochondrial DNA (mtDNA) A3243G is an important cause of some serious mitochondrial diseases, and maternal inheritance of the mutation has been reported. In order to investigate the heredity of the mutation, we measured the ratio of the mutated mtDNA molecule among 32 families of identical twins. Both twins from one family showed 20.16% and 18.49% mutated molecules, and the level is significantly high in comparison with members of other families and control subjects (0.23-0.86%). Their parents, however, showed normal level of mutated molecules (0.70% and 0.66%). The high-level mutation of the twins may be due to a spontaneous event, which occurred during development of germ line of their mother, or oogenesis of their mother, or during early stage of their development.
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Affiliation(s)
- Shinji Harihara
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033, Japan.
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15
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Qiu C, Kumar S, Guo J, Lu J, Shi S, Kalachikov SM, Russo JJ, Naini AB, Schon EA, Ju J. Mitochondrial single nucleotide polymorphism genotyping by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry using cleavable biotinylated dideoxynucleotides. Anal Biochem 2012; 427:202-10. [PMID: 22579594 DOI: 10.1016/j.ab.2012.05.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2012] [Revised: 04/19/2012] [Accepted: 05/02/2012] [Indexed: 10/28/2022]
Abstract
Characterization of mitochondrial DNA (mtDNA) single nucleotide polymorphisms (SNPs) and mutations is crucial for disease diagnosis, which requires accurate and sensitive detection methods and quantification due to mitochondrial heteroplasmy. We report here the characterization of mutations for myoclonic epilepsy with ragged red fibers syndrome using chemically cleavable biotinylated dideoxynucleotides and a mass spectrometry (MS)-based solid phase capture (SPC) single base extension (SBE) assay. The method effectively eliminates unextended primers and primer dimers, and the presence of cleavable linkers between the base and biotin allows efficient desalting and release of the DNA products from solid phase for MS analysis. This approach is capable of high multiplexing, and the use of different length linkers for each of the purines and each of the pyrimidines permits better discrimination of the four bases by MS. Both homoplasmic and heteroplasmic genotypes were accurately determined on different mtDNA samples. The specificity of the method for mtDNA detection was validated by using mitochondrial DNA-negative cells. The sensitivity of the approach permitted detection of less than 5% mtDNA heteroplasmy levels. This indicates that the SPC-SBE approach based on chemically cleavable biotinylated dideoxynucleotides and MS enables rapid, accurate, and sensitive genotyping of mtDNA and has broad applications for genetic analysis.
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Affiliation(s)
- Chunmei Qiu
- Columbia Genome Center, Columbia University College of Physicians and Surgeons, New York, NY 10032, USA
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Classical MERRF phenotype associated with mitochondrial tRNA(Leu) (m.3243A>G) mutation. Eur J Pediatr 2012; 171:859-62. [PMID: 22270878 DOI: 10.1007/s00431-011-1662-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/05/2011] [Accepted: 12/14/2011] [Indexed: 10/14/2022]
Abstract
Myoclonic epilepsy with ragged red fibres (MERRF) and mitochondrial encephalopathy, lactic acidosis and stroke-like episodes (MELAS) are established phenotypes of mitochondrial encephalopathies. Nearly all patients affected by MERRF harbour a mutation in the mitochondrial tRNA(Lys) gene. We report a 13-year-old patient who presented with the classical phenotype of MERRF but was found with the typical mutation of MELAS. The patient presented with myoclonic epilepsy beginning at 10 years of age, a muscle biopsy with ragged red fibres and some COX negative fibres and progressive bilateral MRI hyperintensitivities in the basal ganglia constituting MERRF syndrome but lacked clinical characteristics of MELAS. In particular, stroke-like episodes or lactic acidosis were not present. None of the tRNA mutations described in MERRF were found. However, further analyses showed the tRNA(Leu) mutation m.3243A>G usually found in MELAS to be responsible for the condition in this patient. This report highlights the broad phenotypic variability of mitochondrial encephalopathies with juvenile onset. It shows that m.3243A>G mutations can cause classical MERRF and emphasises the significance of comprehensive genetic studies if mitochondrial disease is suspected clinically.
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Chen CY, Chen HF, Gi SJ, Chi TH, Cheng CK, Hsu CF, Ma YS, Wei YH, Liu CS, Hsieh M. Decreased heat shock protein 27 expression and altered autophagy in human cells harboring A8344G mitochondrial DNA mutation. Mitochondrion 2011; 11:739-49. [PMID: 21679777 DOI: 10.1016/j.mito.2011.05.014] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2010] [Revised: 03/11/2011] [Accepted: 05/27/2011] [Indexed: 02/03/2023]
Abstract
Mitochondrial DNA (mtDNA) mutations are responsible for human neuromuscular diseases caused by mitochondrial dysfunction. Myoclonus epilepsy associated with ragged-red fibers (MERRF) is a maternally inherited mitochondrial encephalomyopathy with various syndromes involving both muscular and nervous systems. The most common mutation in MERRF syndrome, A8344G mutation in mtDNA, has been associated with severe defects in protein synthesis. This defect impairs assembly of complexes in electron transport chain and results in decreased respiratory function of mitochondria. In this study, we showed a significant decrease of the heat shock protein 27 (Hsp27) in lymphoblastoid cells derived from a MERRF patient and in cybrid cells harboring MERRF A8344G mutation. However, normal cytoplasmic distributions of Hsp27 and normal heat shock responses were observed in both wild type and mutant cybrids. Furthermore, overexpression of wild type Hsp27 in mutant MERRF cybrids significantly decreased cell death under staurosporine (STS) treatment, suggesting a protective function of Hsp27 in cells harboring the A8344G mutation of mtDNA. Meanwhile, reverse transcriptase PCR showed no difference in the mRNA level between normal and mutant cybrids, indicating that alterations may occur at the protein level. Evidenced by the decreased levels of Hsp27 upon treatment with proteasome inhibitor, starvation and rapamycin and the accumulation of Hsp27 upon lysosomal inhibitor treatment; Hsp27 may be degraded by the autophagic pathway. In addition, the increased formation of LC3-II and autophagosomes was found in MERRF cybrids under the basal condition, indicating a constitutively-activated autophagic pathway. It may explain, at least partially, the faster turnover of Hsp27 in MERRF cybrids. This study provides information for us to understand that Hsp27 is degraded through the autophagic pathway and that Hsp27 may have a protective role in MERRF cells. Regulating Hsp27 and the autophagic pathway might help develop therapeutic solutions for treatment of MERRF syndrome in the future.
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Affiliation(s)
- Chin-Yi Chen
- Department of Life Science, TungHai University, Taichung, Taiwan, Republic of China
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Moustris A, Edwards MJ, Bhatia KP. Movement disorders and mitochondrial disease. HANDBOOK OF CLINICAL NEUROLOGY 2011; 100:173-92. [PMID: 21496577 DOI: 10.1016/b978-0-444-52014-2.00010-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Affiliation(s)
- Andreas Moustris
- Sobell Department of Motor Neuroscience and Movement Disorders, UCL Institute of Neurology, London, UK
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Scuderi C, Borgione E, Castello F, Lo Giudice M, Fichera M, Elia M, Amato C, Savio M, Di Blasi FD, Vitello GA, Romano S, DiMauro S, Musumeci SA. Coexistence of mitochondrial and nuclear DNA mutations in a woman with mitochondrial encephalomyopathy and double cortex. Mitochondrion 2010; 10:548-54. [PMID: 20433951 DOI: 10.1016/j.mito.2010.04.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2009] [Revised: 03/04/2010] [Accepted: 04/21/2010] [Indexed: 11/18/2022]
Abstract
We describe a 16-year-old girl with mental retardation, myoclonic epilepsy, ataxia, mitochondrial myopathy, sensorineural hearing loss, lactic acidosis, and MRI evidence of diffuse subcortical laminar heterotopia and agyria/pachygyria. Restriction fragment length polymorphism (RFLP) and DNA sequence analyses revealed two pathogenic mutations: a heteroplasmic m.3243A>G in muscle and blood, and a new heterozygous insertion at nt697 in the doublecortin gene (DCX), resulting in a frameshift after amino acid residue 232, with a premature stop codon at amino acid residue 244. This is yet another example of genetic "double trouble" resulting in a complex phenotype.
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Affiliation(s)
- Carmela Scuderi
- Unità Operativa di Malattie Neuromuscolari, IRCCS Oasi Maria SS, Troina, Italy.
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20
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Baiker K, Hofmann S, Fischer A, Gödde T, Medl S, Schmahl W, Bauer MF, Matiasek K. Leigh-like subacute necrotising encephalopathy in Yorkshire Terriers: neuropathological characterisation, respiratory chain activities and mitochondrial DNA. Acta Neuropathol 2009; 118:697-709. [PMID: 19466433 DOI: 10.1007/s00401-009-0548-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2009] [Revised: 05/07/2009] [Accepted: 05/08/2009] [Indexed: 11/26/2022]
Abstract
Our knowledge of molecular mechanisms underlying mitochondrial disorders in humans has increased considerably during the past two decades. Mitochondrial encephalomyopathies have sporadically been reported in dogs. However, molecular and biochemical data that would lend credence to the suspected mitochondrial origin are largely missing. This study was aimed to characterise a Leigh-like subacute necrotising encephalopathy (SNE) in Yorkshire Terriers and to shed light on its enzymatic and genetic background. The possible resemblance to SNE in Alaskan Huskies and to human Leigh syndrome (LS) was another focus of interest. Eleven terriers with imaging and/or gross evidence of V-shaped, non-contiguous, cyst-like cavitations in the striatum, thalamus and brain stem were included. Neuropathological examinations focussed on muscle, brain pathology and mitochondrial ultrastructure. Further investigations encompassed respiratory-chain activities and the mitochondrial DNA. In contrast to mild non-specific muscle findings, brain pathology featured the stereotypic triad of necrotising grey matter lesions with relative preservation of neurons in the aforementioned regions, multiple cerebral infarcts, and severe patchy Purkinje-cell degeneration in the cerebellar vermis. Two dogs revealed a reduced activity of respiratory-chain-complexes I and IV. Genetic analyses obtained a neutral tRNA-Leu(UUR) A-G-transition only. Neuropathologically, SNE in Yorkshire Terriers is nearly identical to the Alaskan Husky form and very similar to human LS. This study, for the first time, demonstrated that canine SNE can be associated with a combined respiratory chain defect. Mitochondrial tRNA mutations and large genetic rearrangements were excluded as underlying aetiology. Further studies, amongst relevant candidates, should focus on nuclear encoded transcription and translation factors.
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Affiliation(s)
- Kerstin Baiker
- Chair of General Pathology and Neuropathology, Institute of Veterinary Pathology, Ludwig-Maximilians University of Munich, Munich, Germany
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Ito S, Shirai W, Asahina M, Hattori T. Clinical and brain MR imaging features focusing on the brain stem and cerebellum in patients with myoclonic epilepsy with ragged-red fibers due to mitochondrial A8344G mutation. AJNR Am J Neuroradiol 2007; 29:392-5. [PMID: 17989367 DOI: 10.3174/ajnr.a0865] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
SUMMARY We report 3 patients with myoclonic epilepsy with ragged-red fibers (MERRF) diagnosed by mitochondrial A8344G mutation. Cerebellar ataxia was the first symptom in all patients. Conventional brain MR imaging showed atrophy of the superior cerebellar peduncles and the cerebellum in all patients and brain stem atrophy in 2 patients. In diffusion tensor analysis, fractional anisotropy of the superior cerebellar peduncles was mildly decreased in 1 patient. There was a discrepancy between clinical disabilities (severe) and radiologic abnormalities (mild). This discrepancy and atrophy of the superior cerebellar peduncles and the cerebellum may be important findings suggesting a diagnosis of MERRF.
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Affiliation(s)
- S Ito
- Department of Neurology, Graduate School of Medicine, Chiba University, Chiba, Japan.
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Finsterer J. Genetic, pathogenetic, and phenotypic implications of the mitochondrial A3243G tRNALeu(UUR) mutation. Acta Neurol Scand 2007; 116:1-14. [PMID: 17587249 DOI: 10.1111/j.1600-0404.2007.00836.x] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Mitochondrial disorders are frequently caused by mutations in mitochondrial genes and usually present as multisystem disease. One of the most frequent mitochondrial mutations is the A3,243G transition in the tRNALeu(UUR) gene. The phenotypic expression of the mutation is variable and comprises syndromic or non-syndromic mitochondrial disorders. Among the syndromic manifestations the mitochondrial encephalopathy, lactacidosis, and stroke-like episode (MELAS) syndrome is the most frequent. In single cases the A3,243G mutation may be associated with maternally inherited diabetes and deafness syndrome, myoclonic epilepsy and ragged-red fibers (MERRF) syndrome, MELAS/MERRF overlap syndrome, maternally inherited Leigh syndrome, chronic external ophthalmoplegia, or Kearns-Sayre syndrome. The wide phenotypic variability of the mutation is explained by the peculiarities of the mitochondrial DNA, such as heteroplasmy and mitotic segregation, resulting in different mutation loads in different tissues and family members. Moreover, there is some evidence that additional mtDNA sequence variations (polymorphisms, haplotypes) influence the phenotype of the A3,243G mutation. This review aims to give an overview on the actual knowledge about the genetic, pathogenetic, and phenotypic implications of the A3,243G mtDNA mutation.
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Affiliation(s)
- J Finsterer
- Krankenanstalt Rudolfstiftung, Vienna, Austria.
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Mkaouar-Rebai E, Tlili A, Masmoudi S, Belguith N, Charfeddine I, Mnif M, Triki C, Fakhfakh F. Mutational analysis of the mitochondrial tRNALeu(UUR) gene in Tunisian patients with mitochondrial diseases. Biochem Biophys Res Commun 2007; 355:1031-7. [PMID: 17336924 DOI: 10.1016/j.bbrc.2007.02.083] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2007] [Accepted: 02/14/2007] [Indexed: 11/29/2022]
Abstract
The mitochondrial tRNA(Leu(UUR)) gene (MTTL) is a hot spot for pathogenic mutations that are associated with mitochondrial diseases with various clinical features. Among these mutations, the A3243G mutation was associated with various types of mitochondrial multisystem disorders, such as MIDD, MELAS, MERRF, PEO, hypertrophic cardiomyopathy, and a subtype of Leigh syndrome. We screened 128 Tunisian patients for the A3243G mutation in the mitochondrial tRNA(Leu(UUR)) gene. This screening was carried out using PCR-RFLP with the restriction endonuclease ApaI. None of the 128 patients or the 100 controls tested were found to carry the mitochondrial A3243G mutation in the tRNA(Leu(UUR)) gene in homoplasmic or heteroplasmic form. After direct sequencing of the entire mitochondrial tRNA(Leu(UUR)) gene and a part of the mitochondrial NADH dehydrogenase 1, we found neither mutations nor polymorphisms in the MTTL1 gene in the tested patients and controls, and we confirmed the absence of the A3243G mutation in this gene. We also found a T3396C transition in the ND1 gene in one family with NSHL which was absent in the other patients and in 100 controls. Neither polymorphisms nor other mutations were found in the mitochondrial tRNA(Leu(UUR)) gene in the tested patients.
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Affiliation(s)
- Emna Mkaouar-Rebai
- Laboratoire de Génétique Moléculaire Humaine, Faculté de Médecine, 3029 Sfax, Tunisia.
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Scaglia F, Northrop JL. The mitochondrial myopathy encephalopathy, lactic acidosis with stroke-like episodes (MELAS) syndrome: a review of treatment options. CNS Drugs 2006; 20:443-64. [PMID: 16734497 DOI: 10.2165/00023210-200620060-00002] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Mitochondrial encephalomyopathies are a multisystemic group of disorders that are characterised by a wide range of biochemical and genetic mitochondrial defects and variable modes of inheritance. Among this group of disorders, the mitochondrial myopathy, encephalopathy, lactic acidosis with stroke-like episodes (MELAS) syndrome is one of the most frequently occurring, maternally inherited mitochondrial disorders. As the name implies, stroke-like episodes are the defining feature of the MELAS syndrome, often occurring before the age of 15 years. The clinical course of this disorder is highly variable, ranging from asymptomatic, with normal early development, to progressive muscle weakness, lactic acidosis, cognitive dysfunction, seizures, stroke-like episodes, encephalopathy and premature death. This syndrome is associated with a number of point mutations in the mitochondrial DNA, with over 80% of the mutations occurring in the dihydrouridine loop of the mitochondrial transfer RNA(Leu(UUR)) [tRNA(Leu)((UUR))] gene. The pathophysiology of the disease is not completely understood; however, several different mechanisms are proposed to contribute to this disease. These include decreased aminoacylation of mitochondrial tRNA, resulting in decreased mitochondrial protein synthesis; changes in calcium homeostasis; and alterations in nitric oxide metabolism. Currently, no consensus criteria exist for treating the MELAS syndrome or mitochondrial dysfunction in other diseases. Many of the therapeutic strategies used have been adopted as the result of isolated case reports or limited clinical studies that have included a heterogeneous population of patients with the MELAS syndrome, other defects in oxidative phosphorylation or lactic acidosis due to disorders of pyruvate metabolism. Current approaches to the treatment of the MELAS syndrome are based on the use of antioxidants, respiratory chain substrates and cofactors in the form of vitamins; however, no consistent benefits have been observed with these treatments.
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Affiliation(s)
- Fernando Scaglia
- Department of Molecular and Human Genetics, Baylor College of Medicine and Texas Children's Hospital, Houston, Texas 77030, USA.
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Morovvati S, Nakagawa M, Sato Y, Hamada K, Higuchi I, Osame M. Phenotypes and mitochondrial DNA substitutions in families with A3243G mutation. Acta Neurol Scand 2002; 106:104-8. [PMID: 12100370 DOI: 10.1034/j.1600-0404.2002.01172.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
OBJECTIVE To clarify the relationship between mitochondrial DNA (mtDNA) sequence variations and phenotypes in patients with A3243G mutation. MATERIALS AND METHODS We studied whole mtDNA sequences in two families with A3243G mutation and characteristic clinical features. Two brothers in Family 1 had shown thiamine deficiency and mitochondrial myopathy without central nervous system involvement. In Family 2, a 16-year-old woman showed the symptoms of mitochondrial encephalopathy, lactic acidosis, and stroke-like episodes (MELAS). Her mother had had diabetes mellitus and died at the age of 42. The proportion of A3243G mtDNA in blood was 87 and 89% in the patients of Family 1, and 25% in the patient and less than 5% in the mother of Family 2. RESULTS The mtDNA analysis revealed the following homoplasmic substitutions: T1520C and C12153T found only in Family 1, and A15954G found only in Family 2. These substitutions were not detected in seven other MELAS patients or in 50 controls. CONCLUSION These substitutions might be specific to these families and could be one of the factors that modulate their clinical features together with the A3243G mutation.
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Affiliation(s)
- S Morovvati
- Third Department of Internal Medicine, Kagoshima University Faculty of Medicine, Kagoshima City, Japan
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Abstract
We studied two siblings with a mitochondrial myopathy, familial thiamine deficiency, and an A3243G mutation of the mitochondrial DNA (mtDNA). The elder brother (patient 1, now 36 years old) developed myopathy and beriberi heart at 20 years of age. Thiamine therapy resolved the cardiac symptoms and hyperpyruvicemia and improved the myopathy. The younger brother presented aged 19 years with a myopathy (patient 2, now 35 years old). Thiamine deficiency was present in the siblings and parents, and ragged-red fibers (RRFs) were noted in muscle biopsies from the siblings. Analysis 17 years later demonstrated thiamine malabsorption and an A3243G mutation of the mtDNA in both siblings and their mother, progressive myopathy, and an increased number of RRFs and elevated serum CKMB activity in patient 1. Thiamine treatment decreased the serum concentrations of lactate and pyruvate in patient 2, but not patient 1. The role of thiamine in mitochondrial dysfunction caused by an electron transfer disorder in the setting of A3243G mtDNA mutation is discussed.
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Affiliation(s)
- Y Sato
- First Department of Internal Medicine, Kurume University School of Medicine, Kurume, Japan.
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Koga Y, Akita Y, Takane N, Sato Y, Kato H. Heterogeneous presentation in A3243G mutation in the mitochondrial tRNA(Leu(UUR)) gene. Arch Dis Child 2000; 82:407-11. [PMID: 10799437 PMCID: PMC1718342 DOI: 10.1136/adc.82.5.407] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
AIMS To clarify the phenotype-genotype relation associated with the A3243G mitochondrial DNA mutation. METHODS Five unrelated probands harbouring the A3243G mutation but presenting different clinical phenotype were analysed. Probands include Leigh syndrome (LS(3243)), mitochondrial myopathy, encephalopathy, lactic acidosis and stroke like episodes (MELAS(3243)), progressive external ophthalmoplegia (PEO(3243)), and mitochondrial diabetes mellitus (MDM(3243)). Extensive clinical, histological, biochemical, and molecular genetic studies were performed on five families. RESULTS All patients showed ragged red fibres (RRF), and focal cytochrome c oxidase (COX) deficiency except for the patient with MDM(3243). The mutation load was highest in the proband with LS(3243) (>90%), who also presented the highest proportion of RRF (68%) and COX negative fibres (10%), and severe complex I plus IV deficiency. These proportions were lower in the probands with PEO(3243) and with MDM(3243). CONCLUSION The most severe clinical phenotype, LS(3243), was associated with the highest proportion of the A3243G mutation as well as the most prominent histological and biochemical abnormalities.
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Affiliation(s)
- Y Koga
- Department of Pediatrics and Child Health, Kurume University School of Medicine, 67 Asahi Machi, Kurume City, Fukuoka 830-0011, Japan.
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Antonická H, Floryk D, Klement P, Stratilová L, Hermanská J, Houstková H, Kalous M, Drahota Z, Zeman J, Houstek J. Defective kinetics of cytochrome c oxidase and alteration of mitochondrial membrane potential in fibroblasts and cytoplasmic hybrid cells with the mutation for myoclonus epilepsy with ragged-red fibres ('MERRF') at position 8344 nt. Biochem J 1999; 342 Pt 3:537-44. [PMID: 10477264 PMCID: PMC1220494] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/13/2023]
Abstract
We have investigated pathogenic effects of the tRNA(Lys) A8344G mutation associated with the syndrome myoclonus epilepsy with ragged-red fibres (MERRF) by using fibroblasts and fibroblast-derived cytoplasmic hybrid cells harbouring different percentages of mutated mitochondrial DNA (mtDNA). The activity of cytochrome c oxidase (COX) in patient fibroblasts with 89% mutated mtDNA was decreased to 20% of the control levels. COX exhibited altered kinetics, with a decreased V(max) for both the low-affinity and high-affinity phases; however, the K(m) values were not significantly changed. The substrate-dependent synthesis of ATP was decreased to 50% of the control. Analysis of the mitochondrial membrane potential, DeltaPsi, in digitonin-treated cells with tetramethylrhodamine methyl ester (TMRM) with the use of flow cytometry showed a 80% decrease in DeltaPsi at state 4 and an increased sensitivity of DeltaPsi to an uncoupler in fibroblasts from the patient. The investigation of transmitochondrial cytoplasmic hybrid clones derived from the patient's fibroblasts enabled us to characterize the relationship between heteroplasmy of the MERRF mutation, COX activity and DeltaPsi. Within the range of 87-73% mutated mtDNA, COX activity was decreased to 5-35% and DeltaPsi was decreased to 6-78%. These results demonstrate that the MERRF mutation affects COX activity and DeltaPsi in different proportions with regard to mutation heteroplasmy and indicate that the biochemical manifestation of the MERRF mutation exerts a very steep threshold of DeltaPsi inhibition.
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Affiliation(s)
- H Antonická
- Institute of Physiology, Academy of Sciences of the Czech Republic, Prague and Department of Pediatrics, 1st Medical Faculty, Charles University, Prague, Czech Republic
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Deschauer M, Wieser T, Neudecker S, Lindner A, Zierz S. Mitochondrial 3243 A-->G mutation (MELAS mutation) associated with painful muscle stiffness. Neuromuscul Disord 1999; 9:305-7. [PMID: 10407850 DOI: 10.1016/s0960-8966(99)00019-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The mitochondrial mutation A-->G at nucleotide position 3243 is associated with mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes (MELAS) and other mitochondrial encephalomyopathies. We found this mutation in a 61-year-old patient who developed at the age of 54 a myopathy with painful muscle stiffness as the predominant symptom. Additionally hypacusis, a mild hemisensory syndrome and impaired glucose tolerance were present. Muscle histopathology showed few ragged red fibers. The mutation was detected heteroplasmatically in DNA from muscle and blood. So far painful muscle stiffness has not been a known phenotype of the 3243 mutation.
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Affiliation(s)
- M Deschauer
- Department of Neurology, Martin-Luther-Universität Halle-Wittenberg, Germany
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Onishi Y, Yamazaki M, Shibuya H, Tanno Y, Tsuji S. MERRF/MELAS overlap syndrome associated with 3243 tRNALeu(UUR)mutation of mitochondrial DNA. Neuropathology 1998. [DOI: 10.1111/j.1440-1789.1998.tb00122.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Topaloğlu H, Seyrantepe V, Kandemir N, Akçören Z, Ozgüç M. mtDNA nt3243 mutation, external ophthalmoplegia, and hypogonadism in an adolescent girl. Pediatr Neurol 1998; 18:429-31. [PMID: 9650685 DOI: 10.1016/s0887-8994(98)00006-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
A 14-year-old girl presented with a 3-month history of easy fatigue and exercise intolerance, especially when climbing stairs. She had a mild ptosis and mild limitation of upward gaze. Her puberty was delayed, and she manifested hypogonadotrophic hypogonadism. Serum lactic and pyruvic acids were elevated. Cranial magnetic resonance imaging was normal. Muscle biopsy documented typical ragged-red fibers. A point mutation at nucleotide 3243 in the tRNALeu(UUR) (typical mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS) mutation) was detected in mitochondrial DNA from both blood and muscle tissues, indicating that our patient was suffering from a mitochondrial myopathy. Hypogonadism may be a manifestation of the MELAS nucleotide 3243 mutation.
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Affiliation(s)
- H Topaloğlu
- Department of Paediatric Neurology, Hacettepe University Children's Hospital, Ankara, Turkey
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Abstract
Rapid progress has been made in the identification of mitochondrial DNA mutations which are typically associated with diseases of the nervous system and muscle. The well established mitochondrial disorders are maternally inherited and males and females are equally affected. An exception is Leber's hereditary optic atrophy (LHON) which is observed much more frequently in males than in females. There are three common point mutations in LHON which can be homoplasmic or heteroplasmic. In mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS) most mutations are single base changes and lie within the tRNA-Leu gene. Point mutations in myoclonic epilepsy with ragged red fibres (MERRF) usually occur within the tRNA-Lys gene but mutations of the tRNA-Leu gene are also observed. MELAS and MERRF mutations are heteroplasmic and there is considerable clinical overlap between these diseases. Point mutations within the ATPase6 gene result in either neuropathy, ataxia and retinitis pigmentosa (NARP) or in Leigh's syndrome. The latter occurs if the mutation is present in the majority of mitochondria (extreme heteroplasmy). Finally, mitochondrial DNA deletions are the cause underlying Kearns-Sayre syndrome (KSS). Apart from the well-established mitochondrial diseases, there is increasing evidence that mitochondrial mutations may also play a role in the neurodegenerative disorders Parkinson, Alzheimer and Huntington disease. The complex I defect found in Parkinson disease is especially interesting in this respect. However, no causative mitochondrial mutation has as yet been established in any of these three common disorders.
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Affiliation(s)
- M B Graeber
- Department of Neuromorphology, Max-Planck-Institute of Psychiatry, Martinsried, Germany.
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