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Rabinovich M, Zambrowski O, Miere A, Bhouri R, Souied E. Neuropathy, ataxia, retinitis pigmentosa: a case of a mother and two siblings. Ophthalmic Genet 2024; 45:193-200. [PMID: 37671548 DOI: 10.1080/13816810.2023.2253905] [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: 12/27/2022] [Accepted: 08/26/2023] [Indexed: 09/07/2023]
Abstract
AIM We describe the ophthalmic manifestations of Neuropathy, ataxia, retinitis pigmentosa (NARP) syndrome in three related patients. METHODS We examined a mother and her two children, who were carriers of the mt 8993T>G mutation. The mother, patient I, is the first known carrier within the family pedigree. Patients II and III are her children from a non-carrier father. NARP syndrome and the heteroplasmy levels were established prior to the first referral of the patients to the Ophthalmology department.We performed a visual acuity testing, followed by a biomicroscopic and fundus examination, as well as additional multimodal imaging testing: optical coherence tomography (OCT) and fundus autofluorescence (FAF), and functional testing: electroretinogram and visual field. RESULTS All patients had the clinical manifestations of NARP syndrome, which were variably expressed symptomatically, on the fundus exams, electroretinogram, and visual fields. CONCLUSIONS Once genetically established, NARP syndrome, as other mitochondrial disorders, has a very variable progression with different degrees of severity. A multimodal approach involving both neurological and ophthalmological diagnosis of NARP syndrome is necessary in order to establish the course of the disease and the measures to be taken.
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Affiliation(s)
- Mark Rabinovich
- Department of Ophthalmology, University of Paris Est-Créteil, Créteil, France
| | - Olivia Zambrowski
- Department of Ophthalmology, University of Paris Est-Créteil, Créteil, France
- Department of Ophthalmology, University hospital Necker Enfants-Malades, APHP, Paris, France
- Centre Ophtalmologique de l'Odéon, Paris, France
| | - Alexandra Miere
- Department of Ophthalmology, University of Paris Est-Créteil, Créteil, France
| | - Rakia Bhouri
- Department of Ophthalmology, University of Paris Est-Créteil, Créteil, France
| | - Eric Souied
- Department of Ophthalmology, University of Paris Est-Créteil, Créteil, France
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2
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Zou W, Zong K, Zhang Z, Shen L, Wang X, Su X, Wang X, Yin T, Liang C, Liu Y, Liang D, Hu C, Cao Y, Ji D. Novel economical, accurate, sensitive, single-cell analytical method for mitochondrial DNA quantification in mtDNA mutation carriers. J Assist Reprod Genet 2023; 40:2197-2209. [PMID: 37462790 PMCID: PMC10440311 DOI: 10.1007/s10815-023-02878-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2023] [Accepted: 06/20/2023] [Indexed: 08/22/2023] Open
Abstract
PURPOSE Although a variety of analytical methods have been developed to detect mitochondrial DNA (mtDNA) heteroplasmy, there are special requirements of mtDNA heteroplasmy quantification for women carrying mtDNA mutations receiving the preimplantation genetic diagnosis (PGD) and prenatal diagnosis (PD) in clinic. These special requirements include various sample types, large sample number, long-term follow-up, and the need for detection of single-cell from biopsied embryos. Therefore, developing an economical, accurate, high-sensitive, and single-cell analytical method for mtDNA heteroplasmy is necessary. METHODS In this study, we developed the Sanger sequencing combined droplet digital polymerase chain reaction (ddPCR) method for mtDNA quantification and compared the results to next-generation sequencing (NGS). A total of seventeen families with twelve mtDNA mutations were recruited in this study. RESULTS The results showed that both Sanger sequencing and ddPCR could be used to analyze the mtDNA heteroplasmy in single-cell samples. There was no statistically significant difference in heteroplasmy levels in common samples with high heteroplasmy (≥ 5%), low heteroplasmy (< 5%), and single-cell samples, either between Sanger sequencing and NGS methods, or between ddPCR and NGS methods (P > 0.05). However, Sanger sequencing was unable to detect extremely low heteroplasmy accurately. But even in samples with extremely low heteroplasmy (0.40% and 0.92%), ddPCR was always able to quantify them. Compared to NGS, Sanger sequencing combined ddPCR analytical methods greatly reduced the cost of sequencing. CONCLUSIONS In conclusion, this study successfully established an economical, accurate, sensitive, single-cell analytical method based on the Sanger sequencing combined ddPCR methods for mtDNA heteroplasmy quantification in a clinical setting.
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Affiliation(s)
- Weiwei Zou
- Reproductive Medicine Center, Department of Obstetrics and Gynecology, the First Affiliated Hospital of Anhui Medical University, No. 218 Jixi Road, Hefei, 230022, Anhui, China
- NHC Key Laboratory of Study On Abnormal Gametes and Reproductive Tract (Anhui Medical University), No. 81 Meishan Road, Hefei, 230032, Anhui, China
| | - Kai Zong
- Technical Center of Hefei Customs District, No. 329 Tunxi Road, Hefei, 230022, Anhui, China
| | - Zhikang Zhang
- Reproductive Medicine Center, Department of Obstetrics and Gynecology, the First Affiliated Hospital of Anhui Medical University, No. 218 Jixi Road, Hefei, 230022, Anhui, China
- NHC Key Laboratory of Study On Abnormal Gametes and Reproductive Tract (Anhui Medical University), No. 81 Meishan Road, Hefei, 230032, Anhui, China
| | - Lingchao Shen
- Reproductive Medicine Center, Department of Obstetrics and Gynecology, the First Affiliated Hospital of Anhui Medical University, No. 218 Jixi Road, Hefei, 230022, Anhui, China
- NHC Key Laboratory of Study On Abnormal Gametes and Reproductive Tract (Anhui Medical University), No. 81 Meishan Road, Hefei, 230032, Anhui, China
| | - Xiaolei Wang
- Reproductive Medicine Center, Department of Obstetrics and Gynecology, the First Affiliated Hospital of Anhui Medical University, No. 218 Jixi Road, Hefei, 230022, Anhui, China
- NHC Key Laboratory of Study On Abnormal Gametes and Reproductive Tract (Anhui Medical University), No. 81 Meishan Road, Hefei, 230032, Anhui, China
| | - Xun Su
- Reproductive Medicine Center, Department of Obstetrics and Gynecology, the First Affiliated Hospital of Anhui Medical University, No. 218 Jixi Road, Hefei, 230022, Anhui, China
- NHC Key Laboratory of Study On Abnormal Gametes and Reproductive Tract (Anhui Medical University), No. 81 Meishan Road, Hefei, 230032, Anhui, China
| | - Xin Wang
- Reproductive Medicine Center, Department of Obstetrics and Gynecology, the First Affiliated Hospital of Anhui Medical University, No. 218 Jixi Road, Hefei, 230022, Anhui, China
- NHC Key Laboratory of Study On Abnormal Gametes and Reproductive Tract (Anhui Medical University), No. 81 Meishan Road, Hefei, 230032, Anhui, China
| | - Tao Yin
- Reproductive Medicine Center, Department of Obstetrics and Gynecology, the First Affiliated Hospital of Anhui Medical University, No. 218 Jixi Road, Hefei, 230022, Anhui, China
- NHC Key Laboratory of Study On Abnormal Gametes and Reproductive Tract (Anhui Medical University), No. 81 Meishan Road, Hefei, 230032, Anhui, China
| | - Chunmei Liang
- Reproductive Medicine Center, Department of Obstetrics and Gynecology, the First Affiliated Hospital of Anhui Medical University, No. 218 Jixi Road, Hefei, 230022, Anhui, China
- NHC Key Laboratory of Study On Abnormal Gametes and Reproductive Tract (Anhui Medical University), No. 81 Meishan Road, Hefei, 230032, Anhui, China
| | - Yajing Liu
- Reproductive Medicine Center, Department of Obstetrics and Gynecology, the First Affiliated Hospital of Anhui Medical University, No. 218 Jixi Road, Hefei, 230022, Anhui, China
- NHC Key Laboratory of Study On Abnormal Gametes and Reproductive Tract (Anhui Medical University), No. 81 Meishan Road, Hefei, 230032, Anhui, China
| | - Dan Liang
- Reproductive Medicine Center, Department of Obstetrics and Gynecology, the First Affiliated Hospital of Anhui Medical University, No. 218 Jixi Road, Hefei, 230022, Anhui, China
- NHC Key Laboratory of Study On Abnormal Gametes and Reproductive Tract (Anhui Medical University), No. 81 Meishan Road, Hefei, 230032, Anhui, China
| | - Chao Hu
- Reproductive Medicine Center, Department of Obstetrics and Gynecology, the First Affiliated Hospital of Anhui Medical University, No. 218 Jixi Road, Hefei, 230022, Anhui, China
- NHC Key Laboratory of Study On Abnormal Gametes and Reproductive Tract (Anhui Medical University), No. 81 Meishan Road, Hefei, 230032, Anhui, China
| | - Yunxia Cao
- Reproductive Medicine Center, Department of Obstetrics and Gynecology, the First Affiliated Hospital of Anhui Medical University, No. 218 Jixi Road, Hefei, 230022, Anhui, China.
- NHC Key Laboratory of Study On Abnormal Gametes and Reproductive Tract (Anhui Medical University), No. 81 Meishan Road, Hefei, 230032, Anhui, China.
| | - Dongmei Ji
- Reproductive Medicine Center, Department of Obstetrics and Gynecology, the First Affiliated Hospital of Anhui Medical University, No. 218 Jixi Road, Hefei, 230022, Anhui, China.
- NHC Key Laboratory of Study On Abnormal Gametes and Reproductive Tract (Anhui Medical University), No. 81 Meishan Road, Hefei, 230032, Anhui, China.
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3
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Soldatov VO, Kubekina MV, Skorkina MY, Belykh AE, Egorova TV, Korokin MV, Pokrovskiy MV, Deykin AV, Angelova PR. Current advances in gene therapy of mitochondrial diseases. J Transl Med 2022; 20:562. [PMID: 36471396 PMCID: PMC9724384 DOI: 10.1186/s12967-022-03685-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Accepted: 10/04/2022] [Indexed: 12/12/2022] Open
Abstract
Mitochondrial diseases (MD) are a heterogeneous group of multisystem disorders involving metabolic errors. MD are characterized by extremely heterogeneous symptoms, ranging from organ-specific to multisystem dysfunction with different clinical courses. Most primary MD are autosomal recessive but maternal inheritance (from mtDNA), autosomal dominant, and X-linked inheritance is also known. Mitochondria are unique energy-generating cellular organelles designed to survive and contain their own unique genetic coding material, a circular mtDNA fragment of approximately 16,000 base pairs. The mitochondrial genetic system incorporates closely interacting bi-genomic factors encoded by the nuclear and mitochondrial genomes. Understanding the dynamics of mitochondrial genetics supporting mitochondrial biogenesis is especially important for the development of strategies for the treatment of rare and difficult-to-diagnose diseases. Gene therapy is one of the methods for correcting mitochondrial disorders.
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Affiliation(s)
- Vladislav O Soldatov
- Core Facility Centre, Institute of Gene Biology, Russian Academy of Sciences, Moscow, Russia.
- Department of Pharmacology and Clinical Pharmacology, Belgorod State National Research University, Belgorod, Russia.
- Laboratory of Genome Editing for Biomedicine and Animal Health, Belgorod State National Research University, Belgorod, Russia.
| | - Marina V Kubekina
- Core Facility Centre, Institute of Gene Biology, Russian Academy of Sciences, Moscow, Russia
| | - Marina Yu Skorkina
- Department of Biochemistry, Belgorod State National Research University, Belgorod, Russia
- Laboratory of Genome Editing for Biomedicine and Animal Health, Belgorod State National Research University, Belgorod, Russia
| | - Andrei E Belykh
- Dioscuri Centre for Metabolic Diseases, Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warsaw, Poland
| | - Tatiana V Egorova
- Laboratory of Modeling and Gene Therapy of Hereditary Diseases, Institute of Gene Biology, Russian Academy of Sciences, Moscow, Russia
| | - Mikhail V Korokin
- Department of Pharmacology and Clinical Pharmacology, Belgorod State National Research University, Belgorod, Russia
| | - Mikhail V Pokrovskiy
- Department of Pharmacology and Clinical Pharmacology, Belgorod State National Research University, Belgorod, Russia
| | - Alexey V Deykin
- Department of Pharmacology and Clinical Pharmacology, Belgorod State National Research University, Belgorod, Russia
- Laboratory of Genome Editing for Biomedicine and Animal Health, Belgorod State National Research University, Belgorod, Russia
| | - Plamena R Angelova
- Department of Clinical and Movement Neurosciences, UCL Queen Square Institute of Neurology, London, UK
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4
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Akiyama N, Shimura M, Yamazaki T, Harashima H, Fushimi T, Tsuruoka T, Ebihara T, Ichimoto K, Matsunaga A, Saito-Tsuruoka M, Yatsuka Y, Kishita Y, Kohda M, Namba A, Kamei Y, Okazaki Y, Kosugi S, Ohtake A, Murayama K. Prenatal diagnosis of severe mitochondrial diseases caused by nuclear gene defects: a study in Japan. Sci Rep 2021; 11:3531. [PMID: 33574353 PMCID: PMC7878886 DOI: 10.1038/s41598-021-81015-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Accepted: 12/28/2020] [Indexed: 12/05/2022] Open
Abstract
Prenatal diagnoses of mitochondrial diseases caused by defects in nuclear DNA (nDNA) or mitochondrial DNA have been reported in several countries except for Japan. The present study aimed to clarify the status of prenatal genetic diagnosis of mitochondrial diseases caused by nDNA defects in Japan. A comprehensive genomic analysis was performed to diagnose more than 400 patients, of which, 13 families (16 cases) had requested prenatal diagnoses. Eight cases diagnosed with wild type homozygous or heterozygous variants same as either of the heterozygous parents continued the pregnancy and delivered healthy babies. Another eight cases were diagnosed with homozygous, compound heterozygous, or hemizygous variants same as the proband. Of these, seven families chose to terminate the pregnancy, while one decided to continue the pregnancy. Neonatal- or infantile-onset mitochondrial diseases show severe phenotypes and lead to lethality. Therefore, such diseases could be candidates for prenatal diagnosis with careful genetic counseling, and prenatal testing could be a viable option for families.
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Affiliation(s)
- Nana Akiyama
- Center for Medical Genetics, Chiba Children's Hospital, Chiba, Japan.,Department of Medical Genetics/Medical Ethics, Kyoto University School of Public Health, Kyoto, Japan
| | - Masaru Shimura
- Department of Metabolism, Chiba Children's Hospital, 579-1 Heta-cho, Midori-ku, Chiba, 266-0007, Japan
| | - Taro Yamazaki
- Department of Pediatrics, Faculty of Medicine, Saitama Medical University, Saitama, Japan
| | - Hiroko Harashima
- Department of Pediatrics, Faculty of Medicine, Saitama Medical University, Saitama, Japan.,Department of Clinical Genomics, Faculty of Medicine, Saitama Medical University, Saitama, Japan
| | - Takuya Fushimi
- Department of Metabolism, Chiba Children's Hospital, 579-1 Heta-cho, Midori-ku, Chiba, 266-0007, Japan
| | - Tomoko Tsuruoka
- Department of Neonatology, Chiba Children's Hospital, Chiba, Japan
| | - Tomohiro Ebihara
- Department of Neonatology, Chiba Children's Hospital, Chiba, Japan
| | - Keiko Ichimoto
- Department of Metabolism, Chiba Children's Hospital, 579-1 Heta-cho, Midori-ku, Chiba, 266-0007, Japan
| | - Ayako Matsunaga
- Department of Metabolism, Chiba Children's Hospital, 579-1 Heta-cho, Midori-ku, Chiba, 266-0007, Japan
| | - Megumi Saito-Tsuruoka
- Department of Clinical Genomics, Faculty of Medicine, Saitama Medical University, Saitama, Japan.,Center for Intractable Diseases, Saitama Medical University Hospital, Saitama, Japan
| | - Yukiko Yatsuka
- Diagnostics and Therapeutics of Intractable Diseases, Intractable Disease Research Center, Graduate School of Medicine, Juntendo University, Tokyo, Japan
| | - Yoshihito Kishita
- Diagnostics and Therapeutics of Intractable Diseases, Intractable Disease Research Center, Graduate School of Medicine, Juntendo University, Tokyo, Japan.,Department of Life Science, Faculty of Science and Engineering, Kindai University, Osaka, Japan
| | - Masakazu Kohda
- Diagnostics and Therapeutics of Intractable Diseases, Intractable Disease Research Center, Graduate School of Medicine, Juntendo University, Tokyo, Japan
| | - Akira Namba
- Department of Clinical Genomics, Faculty of Medicine, Saitama Medical University, Saitama, Japan.,Center for Intractable Diseases, Saitama Medical University Hospital, Saitama, Japan.,Department of Obstetrics and Gynecology, Saitama Medical University Hospital, Saitama, Japan
| | - Yoshimasa Kamei
- Department of Obstetrics and Gynecology, Saitama Medical University Hospital, Saitama, Japan
| | - Yasushi Okazaki
- Diagnostics and Therapeutics of Intractable Diseases, Intractable Disease Research Center, Graduate School of Medicine, Juntendo University, Tokyo, Japan
| | - Shinji Kosugi
- Department of Medical Genetics/Medical Ethics, Kyoto University School of Public Health, Kyoto, Japan
| | - Akira Ohtake
- Department of Pediatrics, Faculty of Medicine, Saitama Medical University, Saitama, Japan. .,Department of Clinical Genomics, Faculty of Medicine, Saitama Medical University, Saitama, Japan. .,Center for Intractable Diseases, Saitama Medical University Hospital, Saitama, Japan.
| | - Kei Murayama
- Center for Medical Genetics, Chiba Children's Hospital, Chiba, Japan. .,Department of Metabolism, Chiba Children's Hospital, 579-1 Heta-cho, Midori-ku, Chiba, 266-0007, Japan. .,Diagnostics and Therapeutics of Intractable Diseases, Intractable Disease Research Center, Graduate School of Medicine, Juntendo University, Tokyo, Japan.
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5
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Theunissen TEJ, Nguyen M, Kamps R, Hendrickx AT, Sallevelt SCEH, Gottschalk RWH, Calis CM, Stassen APM, de Koning B, Mulder-Den Hartog ENM, Schoonderwoerd K, Fuchs SA, Hilhorst-Hofstee Y, de Visser M, Vanoevelen J, Szklarczyk R, Gerards M, de Coo IFM, Hellebrekers DMEI, Smeets HJM. Whole Exome Sequencing Is the Preferred Strategy to Identify the Genetic Defect in Patients With a Probable or Possible Mitochondrial Cause. Front Genet 2018; 9:400. [PMID: 30369941 PMCID: PMC6194163 DOI: 10.3389/fgene.2018.00400] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Accepted: 09/03/2018] [Indexed: 01/03/2023] Open
Abstract
Mitochondrial disorders, characterized by clinical symptoms and/or OXPHOS deficiencies, are caused by pathogenic variants in mitochondrial genes. However, pathogenic variants in some of these genes can lead to clinical manifestations which overlap with other neuromuscular diseases, which can be caused by pathogenic variants in non-mitochondrial genes as well. Mitochondrial pathogenic variants can be found in the mitochondrial DNA (mtDNA) or in any of the 1,500 nuclear genes with a mitochondrial function. We have performed a two-step next-generation sequencing approach in a cohort of 117 patients, mostly children, in whom a mitochondrial disease-cause could likely or possibly explain the phenotype. A total of 86 patients had a mitochondrial disorder, according to established clinical and biochemical criteria. The other 31 patients had neuromuscular symptoms, where in a minority a mitochondrial genetic cause is present, but a non-mitochondrial genetic cause is more likely. All patients were screened for pathogenic variants in the mtDNA and, if excluded, analyzed by whole exome sequencing (WES). Variants were filtered for being pathogenic and compatible with an autosomal or X-linked recessive mode of inheritance in families with multiple affected siblings and/or consanguineous parents. Non-consanguineous families with a single patient were additionally screened for autosomal and X-linked dominant mutations in a predefined gene-set. We identified causative pathogenic variants in the mtDNA in 20% of the patient-cohort, and in nuclear genes in 49%, implying an overall yield of 68%. We identified pathogenic variants in mitochondrial and non-mitochondrial genes in both groups with, obviously, a higher number of mitochondrial genes affected in mitochondrial disease patients. Furthermore, we show that 31% of the disease-causing genes in the mitochondrial patient group were not included in the MitoCarta database, and therefore would have been missed with MitoCarta based gene-panels. We conclude that WES is preferable to panel-based approaches for both groups of patients, as the mitochondrial gene-list is not complete and mitochondrial symptoms can be secondary. Also, clinically and genetically heterogeneous disorders would require sequential use of multiple different gene panels. We conclude that WES is a comprehensive and unbiased approach to establish a genetic diagnosis in these patients, able to resolve multi-genic disease-causes.
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Affiliation(s)
- Tom E J Theunissen
- Department of Genetics and Cell Biology, Maastricht University Medical Centre, Maastricht, Netherlands.,Research Institute GROW, Maastricht University Medical Centre, Maastricht, Netherlands
| | - Minh Nguyen
- Department of Genetics and Cell Biology, Maastricht University Medical Centre, Maastricht, Netherlands.,Research Institute GROW, Maastricht University Medical Centre, Maastricht, Netherlands
| | - Rick Kamps
- Department of Genetics and Cell Biology, Maastricht University Medical Centre, Maastricht, Netherlands
| | - Alexandra T Hendrickx
- Department of Genetics and Cell Biology, Maastricht University Medical Centre, Maastricht, Netherlands
| | - Suzanne C E H Sallevelt
- Department of Genetics and Cell Biology, Maastricht University Medical Centre, Maastricht, Netherlands
| | - Ralph W H Gottschalk
- Department of Genetics and Cell Biology, Maastricht University Medical Centre, Maastricht, Netherlands
| | - Chantal M Calis
- Department of Genetics and Cell Biology, Maastricht University Medical Centre, Maastricht, Netherlands
| | - Alphons P M Stassen
- Department of Genetics and Cell Biology, Maastricht University Medical Centre, Maastricht, Netherlands
| | - Bart de Koning
- Department of Genetics and Cell Biology, Maastricht University Medical Centre, Maastricht, Netherlands
| | | | | | - Sabine A Fuchs
- Department of Metabolic Disorders, University Medical Centre Utrecht, Utrecht, Netherlands
| | | | - Marianne de Visser
- Department of Neurology, Academic Medical Centre Amsterdam, Amsterdam, Netherlands
| | - Jo Vanoevelen
- Department of Genetics and Cell Biology, Maastricht University Medical Centre, Maastricht, Netherlands
| | - Radek Szklarczyk
- Department of Genetics and Cell Biology, Maastricht University Medical Centre, Maastricht, Netherlands.,Research Institute GROW, Maastricht University Medical Centre, Maastricht, Netherlands
| | - Mike Gerards
- Department of Genetics and Cell Biology, Maastricht University Medical Centre, Maastricht, Netherlands.,Maastricht Center for Systems Biology (MaCSBio), Maastricht University Medical Centre, Maastricht, Netherlands
| | - Irenaeus F M de Coo
- Department of Genetics and Cell Biology, Maastricht University Medical Centre, Maastricht, Netherlands.,Department of Pediatric Neurology, Erasmus MC Sophia Children's Hospital, Rotterdam, Netherlands
| | - Debby M E I Hellebrekers
- Department of Genetics and Cell Biology, Maastricht University Medical Centre, Maastricht, Netherlands
| | - Hubert J M Smeets
- Department of Genetics and Cell Biology, Maastricht University Medical Centre, Maastricht, Netherlands.,Research Institute GROW, Maastricht University Medical Centre, Maastricht, Netherlands
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6
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Tyagi A, Pramanik R, Vishnubhatla S, Ali S, Bakhshi R, Chopra A, Singh A, Bakhshi S. Pattern of mitochondrial D-loop variations and their relation with mitochondrial encoded genes in pediatric acute myeloid leukemia. Mutat Res 2018; 810:13-18. [PMID: 29883862 DOI: 10.1016/j.mrfmmm.2018.05.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2018] [Revised: 05/08/2018] [Accepted: 05/24/2018] [Indexed: 06/08/2023]
Abstract
Role of mitochondrial DNA variations, particularly in D loop region, remains investigational in acute myeloid leukaemia (AML). Consecutive 151 pediatric AML patients were prospectively enrolled from June 2013 to August 2016, for evaluating pattern of variations in mitochondrial D-loop region and to determine their association, if any, with expression of mitochondrial-encoded genes. For each patient, D-loop region was sequenced on baseline bone marrow, buccal swab and mother's blood sample. Real time PCR was used for relative gene expression of four mitochondrial DNA encoded genes viz. Nicotinamide-adenine-dineucleotide-dehydrogenase subunit 3 (ND3), Cytochrome-B (Cyt-B), Cytochrome c oxidase-I (COX1) and ATP-synthetase F0 subunit-6 (ATP6). Total 1490 variations were found at 237 positions in D-Loop; 1206 (80.9%) were germline and 284 (19.1%) were somatic. Positions 73-263 were identified as a probable hotspot region. G bases appeared to be most stable nucleotide (least number of single base substitutions) whereas T appeared to be most susceptible to variations with germline T-C being the commonest. Gene expression of Cyt-B was found to be significantly higher for any variation (somatic or germline) at positions 16,192 and 16,327 while it was significantly lower for variations at positions 16,051 and 207. Any variation at positions 152, 207 and 513 significantly decreased COX1 expression while those at positions 16,051 and 152 attenuated ATP6 expression. This first study evaluated type and overall pattern of D-loop variations in AML, and also showed that some of these variations in D loop region might have an effect on the mitochondrial-encoded genes which is new and valuable information in AML genomics.
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Affiliation(s)
- Anudishi Tyagi
- Department of Medical Oncology; Dr. B. R. A. Institute Rotary Cancer Hospital; All India Institute of Medical Sciences, New Delhi, India
| | - Raja Pramanik
- Department of Medical Oncology; Dr. B. R. A. Institute Rotary Cancer Hospital; All India Institute of Medical Sciences, New Delhi, India
| | | | - Safdar Ali
- Shaheed Rajguru College of Applied Sciences, India; University of Delhi , New Delhi
| | - Radhika Bakhshi
- Shaheed Rajguru College of Applied Sciences, India; University of Delhi , New Delhi
| | - Anita Chopra
- Dr. B. R. A. Institute Rotary Cancer Hospital; All India Institute of Medical Sciences, New Delhi, India; Department of Lab oncology
| | - Archna Singh
- All India Institute of Medical Sciences, New Delhi, India; Department of Biochemistry
| | - Sameer Bakhshi
- Department of Medical Oncology; Dr. B. R. A. Institute Rotary Cancer Hospital; All India Institute of Medical Sciences, New Delhi, India.
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7
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Poulton J, Finsterer J, Yu-Wai-Man P. Genetic Counselling for Maternally Inherited Mitochondrial Disorders. Mol Diagn Ther 2018; 21:419-429. [PMID: 28536827 DOI: 10.1007/s40291-017-0279-7] [Citation(s) in RCA: 76] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The aim of this review was to provide an evidence-based approach to frequently asked questions relating to the risk of transmitting a maternally inherited mitochondrial disorder (MID). We do not address disorders linked with disturbed mitochondrial DNA (mtDNA) maintenance, causing mtDNA depletion or multiple mtDNA deletions, as these are autosomally inherited. The review addresses questions regarding prognosis, recurrence risks and the strategies available to prevent disease transmission. The clinical and genetic complexity of maternally inherited MIDs represent a major challenge for patients, their relatives and health professionals. Since many of the genetic and pathophysiological aspects of MIDs remain unknown, counselling of affected patients and at-risk family members remains difficult. MtDNA mutations are maternally transmitted or, more rarely, they are sporadic, occurring de novo (~25%). Females carrying homoplasmic mtDNA mutations will transmit the mutant species to all of their offspring, who may or may not exhibit a similar phenotype depending on modifying, secondary factors. Females carrying heteroplasmic mtDNA mutations will transmit a variable amount of mutant mtDNA to their offspring, which can result in considerable phenotypic heterogeneity among siblings. The majority of mtDNA rearrangements, such as single large-scale deletions, are sporadic, but there is a small risk of recurrence (~4%) among the offspring of affected women. The range and suitability of reproductive choices for prospective mothers is a complex area of mitochondrial medicine that needs to be managed by experienced healthcare professionals as part of a multidisciplinary team. Genetic counselling is facilitated by the identification of the underlying causative genetic defect. To provide more precise genetic counselling, further research is needed to clarify the secondary factors that account for the variable penetrance and the often marked differential expressivity of pathogenic mtDNA mutations both within and between families.
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Affiliation(s)
- Joanna Poulton
- Nuffield Department of Obstetrics and Gynaecology, University of Oxford, Oxford, UK
| | - Josef Finsterer
- Krankenanstalt Rudolfstiftung, Postfach 20, 1180, Vienna, Austria.
| | - Patrick Yu-Wai-Man
- Wellcome Trust Centre for Mitochondrial Research, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK.,Newcastle Eye Centre, Royal Victoria Infirmary, Newcastle upon Tyne, UK.,NIHR Biomedical Research Centre, Moorfields Eye Hospital and UCL Institute of Ophthalmology, London, UK.,Department of Clinical Neurosciences, School of Clinical Medicine, University of Cambridge, Cambridge, UK
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8
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Craven L, Tang MX, Gorman GS, De Sutter P, Heindryckx B. Novel reproductive technologies to prevent mitochondrial disease. Hum Reprod Update 2018. [PMID: 28651360 DOI: 10.1093/humupd/dmx018] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND The use of nuclear transfer (NT) has been proposed as a novel reproductive treatment to overcome the transmission of maternally-inherited mitochondrial DNA (mtDNA) mutations. Pathogenic mutations in mtDNA can cause a wide-spectrum of life-limiting disorders, collectively known as mtDNA disease, for which there are currently few effective treatments and no known cures. The many unique features of mtDNA make genetic counselling challenging for women harbouring pathogenic mtDNA mutations but reproductive options that involve medical intervention are available that will minimize the risk of mtDNA disease in their offspring. This includes PGD, which is currently offered as a clinical treatment but will not be suitable for all. The potential for NT to reduce transmission of mtDNA mutations has been demonstrated in both animal and human models, and has recently been clinically applied not only to prevent mtDNA disease but also for some infertility cases. In this review, we will interrogate the different NT techniques, including a discussion on the available safety and efficacy data of these technologies for mtDNA disease prevention. In addition, we appraise the evidence for the translational use of NT technologies in infertility. OBJECTIVE AND RATIONALE We propose to review the current scientific evidence regarding the clinical use of NT to prevent mitochondrial disease. SEARCH METHODS The scientific literature was investigated by searching PubMed database until Jan 2017. Relevant documents from Human Fertilisation and Embryology Authority as well as reports from both the scientific and popular media were also implemented. The above searches were based on the following key words: 'mitochondria', 'mitochondrial DNA'; 'mitochondrial DNA disease', 'fertility'; 'preimplantation genetic diagnosis', 'nuclear transfer', 'mitochondrial replacement' and 'mitochondrial donation'. OUTCOMES While NT techniques have been shown to effectively reduce the transmission of heteroplasmic mtDNA variants in animal models, and increasing evidence supports their use to prevent the transmission of human mtDNA disease, the need for robust, long-term evaluation is still warranted. Moreover, prenatal screening would still be strongly advocated in combination with the use of these IVF-based technologies. Scientific evidence to support the use of NT and other novel reproductive techniques for infertility is currently lacking. WIDER IMPLICATIONS It is mandatory that any new ART treatments are first adequately assessed in both animal and human models before the cautious implementation of these new therapeutic approaches is clinically undertaken. There is growing evidence to suggest that the translation of these innovative technologies into clinical practice should be cautiously adopted only in highly selected patients. Indeed, given the limited safety and efficacy data, close monitoring of any offspring remains paramount.
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Affiliation(s)
- Lyndsey Craven
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Framlington Place, Newcastle upon Tyne, NE2 4HH, UK
| | - Mao-Xing Tang
- Ghent-Fertility and Stem Cell Team (G-FaST), Department for Reproductive Medicine, Ghent University Hospital, De Pintelaan 185, 9000 Ghent, Belgium
| | - Gráinne S Gorman
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Framlington Place, Newcastle upon Tyne, NE2 4HH, UK
| | - Petra De Sutter
- Ghent-Fertility and Stem Cell Team (G-FaST), Department for Reproductive Medicine, Ghent University Hospital, De Pintelaan 185, 9000 Ghent, Belgium
| | - Björn Heindryckx
- Ghent-Fertility and Stem Cell Team (G-FaST), Department for Reproductive Medicine, Ghent University Hospital, De Pintelaan 185, 9000 Ghent, Belgium
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Abstract
INTRODUCTION Pearson syndrome (PS) is a sporadic and very rare syndrome classically associated with single large-scale deletions of mitochondrial DNA and characterized by refractory sideroblastic anemia during infancy. Areas covered: This review presents an analysis and interpretation of the published data that forms the basis for our understanding of PS. PubMed, Google Scholarand Thompson ISI Web of Knowledge were searched for relevant data. Expert commentary: PS is a very rare mitochodrial disease that involves different organs and systems. Clinical phenotype is extremely variable and may change over the course of disease itself with the possibility both of worsenings and improvements. Outcome is invariably lethal and at the moment no cure is available. Accurate supportive treatment and follow up program in centres with experience in mitochondrial diseases and marrow failure may positively influence quality and duration of life.
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Affiliation(s)
- Piero Farruggia
- a Pediatric Hematology and Oncology Unit, Oncology Department , A.R.N.A.S. Ospedali Civico, Di Cristina e Benfratelli , Palermo , Italy
| | - Floriana Di Marco
- a Pediatric Hematology and Oncology Unit, Oncology Department , A.R.N.A.S. Ospedali Civico, Di Cristina e Benfratelli , Palermo , Italy
| | - Carlo Dufour
- b Clinical and Experimental Hematology Unit, G. Gaslini Children's Hospital , Genova , Italy
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10
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11
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Gómez-Tatay L, Hernández-Andreu JM, Aznar J. Mitochondrial Modification Techniques and Ethical Issues. J Clin Med 2017; 6:E25. [PMID: 28245555 PMCID: PMC5372994 DOI: 10.3390/jcm6030025] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2016] [Revised: 02/07/2017] [Accepted: 02/20/2017] [Indexed: 12/21/2022] Open
Abstract
Current strategies for preventing the transmission of mitochondrial disease to offspring include techniques known as mitochondrial replacement and mitochondrial gene editing. This technology has already been applied in humans on several occasions, and the first baby with donor mitochondria has already been born. However, these techniques raise several ethical concerns, among which is the fact that they entail genetic modification of the germline, as well as presenting safety problems in relation to a possible mismatch between the nuclear and mitochondrial DNA, maternal mitochondrial DNA carryover, and the "reversion" phenomenon. In this essay, we discuss these questions, highlighting the advantages of some techniques over others from an ethical point of view, and we conclude that none of these are ready to be safely applied in humans.
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Affiliation(s)
- Lucía Gómez-Tatay
- Escuela de Doctorado Universidad Católica de Valencia San Vicente Mártir, Valencia 46001, Spain.
- Facultad de Medicina y Odontología, Universidad Católica de Valencia San Vicente Mártir, Departamento de Ciencias Médicas Básicas, Grupo de Medicina Molecular y Mitocondrial, Valencia 46001, Spain.
- Institute of Life Sciences, Universidad Católica de Valencia San Vicente Mártir, Valencia 46001, Spain.
| | - José M Hernández-Andreu
- Facultad de Medicina y Odontología, Universidad Católica de Valencia San Vicente Mártir, Departamento de Ciencias Médicas Básicas, Grupo de Medicina Molecular y Mitocondrial, Valencia 46001, Spain.
- Institute of Life Sciences, Universidad Católica de Valencia San Vicente Mártir, Valencia 46001, Spain.
| | - Justo Aznar
- Institute of Life Sciences, Universidad Católica de Valencia San Vicente Mártir, Valencia 46001, Spain.
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12
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Lane A, Nisker J. "Mitochondrial Replacement" Technologies and Human Germline Nuclear Modification. JOURNAL OF OBSTETRICS AND GYNAECOLOGY CANADA 2016; 38:731-6. [PMID: 27638985 DOI: 10.1016/j.jogc.2016.03.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Accepted: 02/17/2016] [Indexed: 02/08/2023]
Abstract
In 2015 the United Kingdom became the first jurisdiction to approve "mitochondrial replacement techniques" (MRT), thereby dropping prohibitions against creating human embryos with a permanently altered genetic make-up for purposes of reproduction. MRT is a misnomer because in fact it is the nucleus of the oocyte of the woman who wants a genetically related child that is transferred to the enucleated oocyte of a woman paid to undergo IVF to provide the oocyte. MRT thus constitutes nuclear transfer, which is prohibited by criminal sanctions under sections of laws on reproductive cloning in Canada, the United States, Australia, and European countries that regulate assisted reproduction. By adopting policies permitting the use of MRT, the United Kingdom has become the first jurisdiction to counteract an international consensus prohibiting germline modification. Analyses of the legal, ethical, and societal implications of MRT in assisted human reproduction are essential.
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Affiliation(s)
- Alyssa Lane
- Department of Obstetrics and Gynaecology, Schulich School of Medicine & Dentistry, The University of Western Ontario, London ON
| | - Jeff Nisker
- Department of Obstetrics and Gynaecology, Schulich School of Medicine & Dentistry, The University of Western Ontario, London ON; Children's Health Research Institute, London, Ontario
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13
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Bahreini F, Houshmand M, Modaresi MH, Tonekaboni H, Nafissi S, Nazari F, Akrami SM. Mitochondrial Copy Number and D-Loop Variants in Pompe Patients. CELL JOURNAL 2016; 18:405-15. [PMID: 27602323 PMCID: PMC5011329 DOI: 10.22074/cellj.2016.4569] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/11/2015] [Accepted: 01/24/2016] [Indexed: 02/06/2023]
Abstract
Objective Pompe disease is a rare neuromuscular genetic disorder and is classified
into two forms of early and late-onset. Over the past two decades, mitochondrial abnor-
malities have been recognized as an important contributor to an array of neuromuscular
diseases. We therefore aimed to compare mitochondrial copy number and mitochondrial
displacement-loop sequence variation in infantile and adult Pompe patients.
Materials and Methods In this retrospective study, the mitochondrial D-loop sequence
was analyzed by polymerase chain reaction (PCR) and direct sequencing to detect pos-
sible variation in 28 Pompe patients (17 infants and 11 adults). Results were compared
with 100 healthy controls and sequences of all individuals were compared with the Cam-
bridge reference sequence. Real-time PCR was used to quantify mitochondrial DNA copy
number.
Results Among 59 variants identified, 37(62.71%) were present in the infant group,
14(23.333%) in the adult group and 8(13.333%) in both groups. Mitochondrial copy
number in infant patients was lower than adults (P<0.05). A significant frequency differ-
ence was seen between the two groups for 12 single nucleotide polymorphism (SNP).
A novel insertion (317-318 ins CCC) was observed in patients and six SNPs were iden-
tified as neutral variants in controls. There was an inverse association between mito-
chondrial copy number and D-loop variant number (r=0.54).
Conclusion The 317-318 ins CCC was detected as a new mitochondrial variant in
Pompe patients.
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Affiliation(s)
- Fatemeh Bahreini
- Department of Medical Genetics, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
| | - Massoud Houshmand
- Department of Medical Genetic, National Institute of Genetic Engineering and Biotechnology, Tehran, Iran
| | - Mohammad Hossein Modaresi
- Department of Medical Genetics, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
| | - Hassan Tonekaboni
- Department of Pediatric Neurology, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Shahriar Nafissi
- Iranian Center for Neurological Research, Tehran University of Medical Sciences, Tehran, Iran
| | - Ferdoss Nazari
- Iranian Center for Neurological Research, Tehran University of Medical Sciences, Tehran, Iran
| | - Seyed Mohammad Akrami
- Department of Medical Genetics, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
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14
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Darbandi S, Darbandi M, Khorshid HRK, Sadeghi MR, Al-Hasani S, Agarwal A, Shirazi A, Heidari M, Akhondi MM. Experimental strategies towards increasing intracellular mitochondrial activity in oocytes: A systematic review. Mitochondrion 2016; 30:8-17. [PMID: 27234976 DOI: 10.1016/j.mito.2016.05.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Revised: 04/04/2016] [Accepted: 05/20/2016] [Indexed: 12/19/2022]
Abstract
PURPOSE The mitochondrial complement is critical in sustaining the earliest stages of life. To improve the Assisted Reproductive Technology (ART), current methods of interest were evaluated for increasing the activity and copy number of mitochondria in the oocyte cell. METHODS This covered the researches from 1966 to September 2015. RESULTS The results provided ten methods that can be studied individually or simultaneously. CONCLUSION Though the use of these techniques generated great concern about heteroplasmy observation in humans, it seems that with study on these suggested methods there is real hope for effective treatments of old oocyte or oocytes containing mitochondrial problems in the near future.
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Affiliation(s)
- Sara Darbandi
- Reproductive Biotechnology Research Center, Avicenna Research Institute, ACECR, Tehran, Iran.
| | - Mahsa Darbandi
- Reproductive Biotechnology Research Center, Avicenna Research Institute, ACECR, Tehran, Iran.
| | | | - Mohammad Reza Sadeghi
- Reproductive Biotechnology Research Center, Avicenna Research Institute, ACECR, Tehran, Iran.
| | - Safaa Al-Hasani
- Reproductive Medicine Unit, University of Schleswig-Holstein, Luebeck, Germany.
| | - Ashok Agarwal
- Center for Reproductive Medicine, Glickman Urological and Kidney Institute, Cleveland Clinic, Cleveland, OH, USA.
| | - Abolfazl Shirazi
- Reproductive Biotechnology Research Center, Avicenna Research Institute, ACECR, Tehran, Iran.
| | - Mahnaz Heidari
- Reproductive Biotechnology Research Center, Avicenna Research Institute, ACECR, Tehran, Iran. M.@avicenna.ar.ir
| | - Mohammad Mehdi Akhondi
- Reproductive Biotechnology Research Center, Avicenna Research Institute, ACECR, Tehran, Iran.
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15
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Saunders CJ, Moon SH, Liu X, Thiffault I, Coffman K, LePichon JB, Taboada E, Smith LD, Farrow EG, Miller N, Gibson M, Patterson M, Kingsmore SF, Gross RW. Loss of function variants in human PNPLA8 encoding calcium-independent phospholipase A2 γ recapitulate the mitochondriopathy of the homologous null mouse. Hum Mutat 2015; 36:301-6. [PMID: 25512002 DOI: 10.1002/humu.22743] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2014] [Accepted: 12/09/2014] [Indexed: 12/13/2022]
Abstract
Mitochondriopathies are a group of clinically heterogeneous genetic diseases caused by defects in mitochondrial metabolism, bioenergetic efficiency, and/or signaling functions. The large majority of proteins involved in mitochondrial function are encoded by nuclear genes, with many yet to be associated with human disease. We performed exome sequencing on a young girl with a suspected mitochondrial myopathy that manifested as progressive muscle weakness, hypotonia, seizures, poor weight gain, and lactic acidosis. She was compound heterozygous for two frameshift mutations, p.Asn112HisfsX29 and p.Leu659AlafsX4, in the PNPLA8 gene, which encodes mitochondrial calcium-independent phospholipase A2 γ (iPLA2 γ). Western blot analysis of affected muscle displayed the absence of PNPLA8 protein. iPLA2 s are critical mediators of a variety of cellular processes including growth, metabolism, and lipid second messenger generation, exerting their functions through catalyzing the cleavage of the acyl groups in glycerophospholipids. The clinical presentation, muscle histology and the mitochondrial ultrastructural abnormalities of this proband are highly reminiscent of Pnpla8 null mice. Although other iPLA2 -related diseases have been identified, namely, infantile neuroaxonal dystrophy and neutral lipid storage disease with myopathy, this is the first report of PNPLA8-related disease in a human. We suggest PNPLA8 join the increasing list of human genes involved in lipid metabolism associated with neuromuscular diseases due to mitochondrial dysfunction.
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Affiliation(s)
- Carol J Saunders
- Center for Pediatric Genomic Medicine, Children's Mercy Hospitals, Kansas City, Missouri
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16
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Tischner C, Wenz T. Keep the fire burning: Current avenues in the quest of treating mitochondrial disorders. Mitochondrion 2015; 24:32-49. [DOI: 10.1016/j.mito.2015.06.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2015] [Revised: 06/18/2015] [Accepted: 06/24/2015] [Indexed: 12/18/2022]
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17
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Smeets HJ, Sallevelt SC, Dreesen JC, de Die-Smulders CE, de Coo IF. Preventing the transmission of mitochondrial DNA disorders using prenatal or preimplantation genetic diagnosis. Ann N Y Acad Sci 2015; 1350:29-36. [DOI: 10.1111/nyas.12866] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Affiliation(s)
- Hubert J.M. Smeets
- Department of Clinical Genetics; Maastricht University Medical Centre; Maastricht the Netherlands
- CARIM School for Cardiovascular Diseases; Maastricht University; Maastricht the Netherlands
- GROW School for Oncology and Developmental Biology; Maastricht University; Maastricht the Netherlands
| | - Suzanne C.E.H. Sallevelt
- Department of Clinical Genetics; Maastricht University Medical Centre; Maastricht the Netherlands
- CARIM School for Cardiovascular Diseases; Maastricht University; Maastricht the Netherlands
| | - Jos C.F.M. Dreesen
- Department of Clinical Genetics; Maastricht University Medical Centre; Maastricht the Netherlands
| | - Christine E.M. de Die-Smulders
- Department of Clinical Genetics; Maastricht University Medical Centre; Maastricht the Netherlands
- GROW School for Oncology and Developmental Biology; Maastricht University; Maastricht the Netherlands
| | - Irenaeus F.M. de Coo
- Department of Neurology; Erasmus MC-Sophia Children's Hospital; Rotterdam the Netherlands
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18
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MitoTALEN: A General Approach to Reduce Mutant mtDNA Loads and Restore Oxidative Phosphorylation Function in Mitochondrial Diseases. Mol Ther 2015; 23:1592-9. [PMID: 26159306 DOI: 10.1038/mt.2015.126] [Citation(s) in RCA: 130] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2015] [Accepted: 06/21/2015] [Indexed: 12/23/2022] Open
Abstract
We have designed mitochondrially targeted transcription activator-like effector nucleases or mitoTALENs to cleave specific sequences in the mitochondrial DNA (mtDNA) with the goal of eliminating mtDNA carrying pathogenic point mutations. To test the generality of the approach, we designed mitoTALENs to target two relatively common pathogenic mtDNA point mutations associated with mitochondrial diseases: the m.8344A>G tRNA(Lys) gene mutation associated with myoclonic epilepsy with ragged red fibers (MERRF) and the m.13513G>A ND5 mutation associated with MELAS/Leigh syndrome. Transmitochondrial cybrid cells harbouring the respective heteroplasmic mtDNA mutations were transfected with the respective mitoTALEN and analyzed after different time periods. MitoTALENs efficiently reduced the levels of the targeted pathogenic mtDNAs in the respective cell lines. Functional assays showed that cells with heteroplasmic mutant mtDNA were able to recover respiratory capacity and oxidative phosphorylation enzymes activity after transfection with the mitoTALEN. To improve the design in the context of the low complexity of mtDNA, we designed shorter versions of the mitoTALEN specific for the MERRF m.8344A>G mutation. These shorter mitoTALENs also eliminated the mutant mtDNA. These reductions in size will improve our ability to package these large sequences into viral vectors, bringing the use of these genetic tools closer to clinical trials.
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19
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Kabunga P, Lau AK, Phan K, Puranik R, Liang C, Davis RL, Sue CM, Sy RW. Systematic review of cardiac electrical disease in Kearns–Sayre syndrome and mitochondrial cytopathy. Int J Cardiol 2015; 181:303-10. [DOI: 10.1016/j.ijcard.2014.12.038] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/12/2014] [Revised: 12/06/2014] [Accepted: 12/12/2014] [Indexed: 11/27/2022]
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20
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Peralta S, Torraco A, Iommarini L, Diaz F. Mitochondrial Diseases Part III: Therapeutic interventions in mouse models of OXPHOS deficiencies. Mitochondrion 2015; 23:71-80. [PMID: 25638392 DOI: 10.1016/j.mito.2015.01.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2015] [Accepted: 01/22/2015] [Indexed: 12/19/2022]
Abstract
Mitochondrial defects are the cause of numerous disorders affecting the oxidative phosphorylation system (OXPHOS) in humans leading predominantly to neurological and muscular degeneration. The molecular origin, manifestations, and progression of mitochondrial diseases have a broad spectrum, which makes very challenging to find a globally effective therapy. The study of the molecular mechanisms underlying the mitochondrial dysfunction indicates that there is a wide range of pathways, enzymes and molecules that can be potentially targeted for therapeutic purposes. Therefore, focusing on the pathology of the disease is essential to design new treatments. In this review, we will summarize and discuss the different therapeutic interventions tested in some mouse models of mitochondrial diseases emphasizing the molecular mechanisms of action and their potential applications.
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Affiliation(s)
- Susana Peralta
- Department of Neurology, University of Miami, Miller School of Medicine, Miami, FL 33136, USA.
| | - Alessandra Torraco
- Neuromuscular and Neurodegenerative Disorders, Laboratory of Molecular Medicine, Bambino Gesù Children's Hospital, IRCCS, Viale di San Paolo, 15 - 00146, Rome, Italy.
| | - Luisa Iommarini
- Department of Pharmacy and Biotechnology (FABIT), University of Bologna, Via Irnerio 42, 40126, Bologna, Italy.
| | - Francisca Diaz
- Department of Neurology, University of Miami, Miller School of Medicine, Miami, FL 33136, USA.
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Nesbitt V, Alston CL, Blakely EL, Fratter C, Feeney CL, Poulton J, Brown GK, Turnbull DM, Taylor RW, McFarland R. A national perspective on prenatal testing for mitochondrial disease. Eur J Hum Genet 2014; 22:1255-9. [PMID: 24642831 PMCID: PMC4200441 DOI: 10.1038/ejhg.2014.35] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2013] [Revised: 12/17/2013] [Accepted: 01/16/2014] [Indexed: 01/30/2023] Open
Abstract
Mitochondrial diseases affect >1 in 7500 live births and may be due to mutations in either mitochondrial DNA (mtDNA) or nuclear DNA (nDNA). Genetic counselling for families with mitochondrial diseases, especially those due to mtDNA mutations, provides unique and difficult challenges particularly in relation to disease transmission and prevention. We have experienced an increasing demand for prenatal diagnostic testing from families affected by mitochondrial disease since we first offered this service in 2007. We review the diagnostic records of the 62 prenatal samples (17 mtDNA and 45 nDNA) analysed since 2007, the reasons for testing, mutation investigated and the clinical outcome. Our findings indicate that prenatal testing for mitochondrial disease is reliable and informative for the nuclear and selected mtDNA mutations we have tested. Where available, the results of mtDNA heteroplasmy analyses from other family members are helpful in interpreting the prenatal mtDNA test result. This is particularly important when the mutation is rare or the mtDNA heteroplasmy is observed at intermediate levels. At least 11 cases of mitochondrial disease were prevented following prenatal testing, 3 of which were mtDNA disease. On the basis of our results, we believe that prenatal testing for mitochondrial disease is an important option for couples where appropriate genetic analyses and pre/post-test counselling can be provided.
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Affiliation(s)
- Victoria Nesbitt
- Wellcome Trust Centre for Mitochondrial Research, The Medical School, Institute for Ageing and Health, Newcastle University, Newcastle-upon-Tyne, UK
| | - Charlotte L Alston
- NHS Specialised Services for Rare Mitochondrial Disorders of Adults and Children UK, Oxford, UK
| | - Emma L Blakely
- NHS Specialised Services for Rare Mitochondrial Disorders of Adults and Children UK, Oxford, UK
| | - Carl Fratter
- NHS Specialised Services for Rare Mitochondrial Disorders of Adults and Children UK, Oxford, UK
- Oxford Medical Genetics Laboratories, Oxford University Hospitals NHS Trust, Oxford, UK
| | - Catherine L Feeney
- NHS Specialised Services for Rare Mitochondrial Disorders of Adults and Children UK, Oxford, UK
| | - Joanna Poulton
- NHS Specialised Services for Rare Mitochondrial Disorders of Adults and Children UK, Oxford, UK
- Nuffield Department of Obstetrics and Gynaecology, University of Oxford, John Radcliffe Hospital, Oxford, UK
| | - Garry K Brown
- NHS Specialised Services for Rare Mitochondrial Disorders of Adults and Children UK, Oxford, UK
- Department of Biochemistry, University of Oxford, Oxford, UK
| | - Doug M Turnbull
- Wellcome Trust Centre for Mitochondrial Research, The Medical School, Institute for Ageing and Health, Newcastle University, Newcastle-upon-Tyne, UK
- NHS Specialised Services for Rare Mitochondrial Disorders of Adults and Children UK, Oxford, UK
| | - Robert W Taylor
- Wellcome Trust Centre for Mitochondrial Research, The Medical School, Institute for Ageing and Health, Newcastle University, Newcastle-upon-Tyne, UK
- NHS Specialised Services for Rare Mitochondrial Disorders of Adults and Children UK, Oxford, UK
| | - Robert McFarland
- Wellcome Trust Centre for Mitochondrial Research, The Medical School, Institute for Ageing and Health, Newcastle University, Newcastle-upon-Tyne, UK
- NHS Specialised Services for Rare Mitochondrial Disorders of Adults and Children UK, Oxford, UK
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22
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Baertling F, Rodenburg RJ, Schaper J, Smeitink JA, Koopman WJH, Mayatepek E, Morava E, Distelmaier F. A guide to diagnosis and treatment of Leigh syndrome. J Neurol Neurosurg Psychiatry 2014; 85:257-65. [PMID: 23772060 DOI: 10.1136/jnnp-2012-304426] [Citation(s) in RCA: 154] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Leigh syndrome is a devastating neurodegenerative disease, typically manifesting in infancy or early childhood. However, also late-onset cases have been reported. Since its first description by Denis Archibald Leigh in 1951, it has evolved from a postmortem diagnosis, strictly defined by histopathological observations, to a clinical entity with indicative laboratory and radiological findings. Hallmarks of the disease are symmetrical lesions in the basal ganglia or brain stem on MRI, and a clinical course with rapid deterioration of cognitive and motor functions. Examinations of fresh muscle tissue or cultured fibroblasts are important tools to establish a biochemical and genetic diagnosis. Numerous causative mutations in mitochondrial and nuclear genes, encoding components of the oxidative phosphorylation system have been described in the past years. Moreover, dysfunctions in pyruvate dehydrogenase complex or coenzyme Q10 metabolism may be associated with Leigh syndrome. To date, there is no cure for affected patients, and treatment options are mostly unsatisfactory. Here, we review the most important clinical aspects of Leigh syndrome, and discuss diagnostic steps as well as treatment options.
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Affiliation(s)
- Fabian Baertling
- Department of General Pediatrics, Neonatology and Pediatric Cardiology, University Children's Hospital, Heinrich-Heine-University, , Düsseldorf, Germany
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Wallace DC, Chalkia D. Mitochondrial DNA genetics and the heteroplasmy conundrum in evolution and disease. Cold Spring Harb Perspect Biol 2013; 5:a021220. [PMID: 24186072 PMCID: PMC3809581 DOI: 10.1101/cshperspect.a021220] [Citation(s) in RCA: 441] [Impact Index Per Article: 40.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The unorthodox genetics of the mtDNA is providing new perspectives on the etiology of the common "complex" diseases. The maternally inherited mtDNA codes for essential energy genes, is present in thousands of copies per cell, and has a very high mutation rate. New mtDNA mutations arise among thousands of other mtDNAs. The mechanisms by which these "heteroplasmic" mtDNA mutations come to predominate in the female germline and somatic tissues is poorly understood, but essential for understanding the clinical variability of a range of diseases. Maternal inheritance and heteroplasmy also pose major challengers for the diagnosis and prevention of mtDNA disease.
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Affiliation(s)
- Douglas C Wallace
- Center for Mitochondrial and Epigenomic Medicine, The Children's Hospital of Philadelphia, Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104
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24
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Novel mitochondrial C15620A variant may modulate the phenotype of mitochondrial G11778A mutation in a Chinese family with Leigh syndrome. Neuromolecular Med 2013; 16:119-26. [PMID: 24062162 DOI: 10.1007/s12017-013-8264-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2013] [Accepted: 09/03/2013] [Indexed: 01/25/2023]
Abstract
We report a case of 3-year-old boy who presented with Leigh syndrome but carried a mitochondrial G11778A mutation in the fourth subunit of the NADH dehydrogenase gene (MTND4). Additional to G11778A mutation, a novel C15620A variant was detected, which resulted in the conversion from leucine to isoleucine in the mitochondrial cytochrome b gene. As G11778A mutation is the most common mutation associated with Leber's hereditary optic neuropathy (LHON), given the unusual phenotype, the C15620A mutation was postulated to influence the pathogenicity of the G11778A mutation. This case further expands the clinical spectrum associated with the primary G11778A LHON mutation.
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Wray CD, Friederich MW, du Sart D, Pantaleo S, Smet J, Kucera C, Fenton L, Scharer G, Van Coster R, Van Hove JLK. A new mutation in MT-ND1 m.3928G>C p.V208L causes Leigh disease with infantile spasms. Mitochondrion 2013; 13:656-61. [PMID: 24063851 DOI: 10.1016/j.mito.2013.09.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2013] [Revised: 08/30/2013] [Accepted: 09/17/2013] [Indexed: 01/14/2023]
Abstract
New mutations in mitochondrial DNA encoded genes of complex I are rarely reported. An infant developed Leigh disease with infantile spasms. Complex I enzyme activity was deficient and response to increasing coenzyme Q concentrations was reduced. Complex I assembly was intact. A new mutation in MT-ND1 m.3928G>C p.V208L, affecting a conserved amino acid in a critical domain, part of the coenzyme Q binding pocket, was present at high heteroplasmy. The unaffected mother did not carry measurable mutant mitochondrial DNA, but concern remained for gonadal mosaicism. Prenatal testing was possible for a subsequent sibling. The ND1 p.V208L mutation causes Leigh disease.
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Affiliation(s)
- Carter D Wray
- Department of Pediatrics, University of Colorado, 13121 East 17th Avenue, Aurora, CO 80045, USA; Division of Pediatric Neurology, Oregon Health Sciences Center, 3181 SW Sam Jackson Park Rd, Portland, OR 97239, USA
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Smeets HJM. Preventing the transmission of mitochondrial DNA disorders: selecting the good guys or kicking out the bad guys. Reprod Biomed Online 2013; 27:599-610. [PMID: 24135157 DOI: 10.1016/j.rbmo.2013.08.007] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2013] [Revised: 07/26/2013] [Accepted: 08/01/2013] [Indexed: 01/30/2023]
Abstract
Mitochondrial disorders represent the most common group of inborn errors of metabolism. Clinical manifestations can be extremely variable, ranging from single affected tissues to multisystemic syndromes. Maternally inherited mitochondrial DNA (mtDNA) mutations are a frequent cause, affecting about one in 5000 individuals. The expression of mtDNA mutations differs from nuclear gene defects. Mutations are either homoplasmic or heteroplasmic, and in the latter case disease becomes manifest when the mutation load exceeds a tissue-specific threshold. Mutation load can vary between tissues and in time, and often an exact correlation between mutation load and clinical manifestations is lacking. Because of the possible clinical severity, the lack of treatment and the high recurrence risk of affected offspring for female carriers, couples request prevention of transmission of mtDNA mutations. Previously, choices have been limited due to a segregational bottleneck, which makes the mtDNA mutation load in embryos highly variable and the consequences largely unpredictable. However, recently it was shown that preimplantation genetic diagnosis offers a fair chance of unaffected offspring to carriers of heteroplasmic mtDNA mutations. Technically and ethically challenging possibilities, such maternal spindle transfer and pronuclear transfer, are emerging and providing carriers additional prospects of giving birth to a healthy child.
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Affiliation(s)
- Hubert J M Smeets
- Unit Clinical Genomics, Department of Genetics and Cell Biology, School for Growth and Development and for Cardiovascular Research, Maastricht University Medical Centre, Maastricht, The Netherlands.
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Barić I, Fumić K, Petković Ramadža D, Sperl W, Zimmermann FA, Muačević-Katanec D, Mitrović Z, Pažanin L, Cvitanović Šojat L, Kekez T, Reiner Z, Mayr JA. Mitochondrial myopathy associated with a novel 5522G>A mutation in the mitochondrial tRNA(Trp) gene. Eur J Hum Genet 2013; 21:871-5. [PMID: 23232693 PMCID: PMC3722682 DOI: 10.1038/ejhg.2012.272] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2012] [Revised: 10/22/2012] [Accepted: 11/13/2012] [Indexed: 12/31/2022] Open
Abstract
We report a novel pathogenic mutation of the mitochondrial transfer RNA (tRNA) gene for tryptophan in a patient with isolated myopathy and persistently elevated creatine kinase. Muscle studies revealed ragged red fibres and decreased activity of respiratory chain complex I and cytochrome c oxidase (COX). Sequencing of the 22 mitochondrial tRNA genes revealed a mutation m.5522G>A, which alters a conserved base pairing in the D-stem of the tRNA for tryptophan. The mutation was heteroplasmic with a mutational load between 88 and 99% in COX-negative fibres. This case contributes to the genetic heterogeneity of mitochondrial diseases caused by mutations in mitochondrial tRNA genes.
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Affiliation(s)
- Ivo Barić
- Department of Paediatrics, University Hospital Centre Zagreb, Zagreb, Croatia.
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Tarnopolsky M, Meaney B, Robinson B, Sheldon K, Boles RG. Severe infantile leigh syndrome associated with a rare mitochondrial ND6 mutation, m.14487T>C. Am J Med Genet A 2013; 161A:2020-3. [PMID: 23813926 DOI: 10.1002/ajmg.a.36000] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2013] [Accepted: 02/23/2013] [Indexed: 11/06/2022]
Abstract
We describe a case of severe infantile-onset complex I deficiency in association with an apparent de novo near-homoplasmic mutation (m.14487T>C) in the mitochondrial ND6 gene, which was previously associated with Leigh syndrome and other neurological disorders. The mutation was near-homoplasmic in muscle by NextGen sequencing (99.4% mutant), homoplasmic in muscle by Sanger sequencing, and it was associated with a severe complex I deficiency in both muscle and fibroblasts. This supports previous data regarding Leigh syndrome being on the severe end of a phenotypic spectrum including progressive myoclonic epilepsy, childhood-onset dystonia, bilateral striatal necrosis, and optic atrophy, depending on the proportion of mutant heteroplasmy. While the mother in all previously reported cases was heteroplasmic, the mother and brother of this case were homoplasmic for the wild-type, m.14487T. Importantly, the current data demonstrate the potential for cases of mutations that were previously reported to be homoplasmic by Sanger sequencing to be less homoplasmic by NextGen sequencing. This case underscores the importance of considering mitochondrial DNA mutations in families with a negative family history, even in offspring of those who have tested negative for a specific mtDNA mutation.
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Affiliation(s)
- Mark Tarnopolsky
- Department of Pediatrics, McMaster University Medical Center, Hamilton, ON, Canada.
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Dinwiddie DL, Smith LD, Miller NA, Atherton AM, Farrow EG, Strenk ME, Soden SE, Saunders CJ, Kingsmore SF. Diagnosis of mitochondrial disorders by concomitant next-generation sequencing of the exome and mitochondrial genome. Genomics 2013; 102:148-56. [PMID: 23631824 DOI: 10.1016/j.ygeno.2013.04.013] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2013] [Revised: 04/18/2013] [Accepted: 04/19/2013] [Indexed: 01/22/2023]
Abstract
Mitochondrial diseases are notoriously difficult to diagnose due to extreme locus and allelic heterogeneity, with both nuclear and mitochondrial genomes potentially liable. Using exome sequencing we demonstrate the ability to rapidly and cost effectively evaluate both the nuclear and mitochondrial genomes to obtain a molecular diagnosis for four patients with three distinct mitochondrial disorders. One patient was found to have Leigh syndrome due to a mutation in MT-ATP6, two affected siblings were discovered to be compound heterozygous for mutations in the NDUFV1 gene, which causes mitochondrial complex I deficiency, and one patient was found to have coenzyme Q10 deficiency due to compound heterozygous mutations in COQ2. In all cases conventional diagnostic testing failed to identify a molecular diagnosis. We suggest that additional studies should be conducted to evaluate exome sequencing as a primary diagnostic test for mitochondrial diseases, including those due to mtDNA mutations.
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Affiliation(s)
- Darrell L Dinwiddie
- Center for Pediatric Genomic Medicine, Children's Mercy Hospital, Kansas City, MO 64108, USA.
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30
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Abstract
Mitochondrial diseases are a genetically and clinically diverse group of disorders that arise as a result of dysfunction of the mitochondria. Mitochondrial disorders can be caused by alterations in nuclear DNA and/or mitochondrial DNA. Although some mitochondrial syndromes have been described clearly in the literature many others present as challenging clinical cases with multisystemic involvement at variable ages of onset. Given the clinical variability and genetic heterogeneity of these conditions, patients and their families often experience a lengthy and complicated diagnostic process. The diagnostic journey may be characterized by heightened levels of uncertainty due to the delayed diagnosis and the absence of a clear prognosis, among other factors. Uncertainty surrounding issues of family planning and genetic testing may also affect the patient. The role of the genetic counselor is particularly important to help explain these complexities and support the patient and family's ability to achieve effective coping strategies in dealing with increased levels of uncertainty.
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Affiliation(s)
- Jodie M. Vento
- />Division of Child Neurology, Children’s Hospital of Pittsburgh of UPMC, 4401 Penn Avenue, Pittsburgh, PA 15224 USA
| | - Belen Pappa
- />Department of Neurology, Children’s National Medical Center, 111 Michigan Avenue NW, Washington, DC 20010 USA
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Siebel S, Solomon B. Mitochondrial Factors and VACTERL Association-Related Congenital Malformations. Mol Syndromol 2013; 4:63-73. [PMID: 23653577 PMCID: PMC3638779 DOI: 10.1159/000346301] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
VACTERL/VATER association is a group of congenital malformations characterized by at least 3 of the following findings: vertebral defects, anal atresia, cardiac defects, tracheo-esophageal fistula, renal anomalies, and limb abnormalities. To date, no unifying etiology for VACTERL/VATER association has been established, and there is strong evidence for causal heterogeneity. VACTERL/VATER association has many overlapping characteristics with other congenital disorders that involve multiple malformations. In addition to these other conditions, some of which have known molecular causes, certain aspects of VACTERL/VATER association have similarities with the manifestations of disorders caused by mitochondrial dysfunction. Mitochondrial dysfunction can result from a number of distinct causes and can clinically manifest in diverse presentations; accurate diagnosis can be challenging. Case reports of individuals with VACTERL association and confirmed mitochondrial dysfunction allude to the possibility of mitochondrial involvement in the pathogenesis of VACTERL/VATER association. Further, there is biological plausibility involving mitochondrial dysfunction as a possible etiology related to a diverse group of congenital malformations, including those seen in at least a subset of individuals with VACTERL association.
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Affiliation(s)
| | - B.D. Solomon
- Medical Genetics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, Md., USA
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Samuels DC, Wonnapinij P, Chinnery PF. Preventing the transmission of pathogenic mitochondrial DNA mutations: Can we achieve long-term benefits from germ-line gene transfer? Hum Reprod 2013; 28:554-9. [PMID: 23297368 PMCID: PMC3571501 DOI: 10.1093/humrep/des439] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Mitochondrial medicine is one of the few areas of genetic disease where germ-line transfer is being actively pursued as a treatment option. All of the germ-line transfer methods currently under development involve some carry-over of the maternal mitochondrial DNA (mtDNA) heteroplasmy, potentially delivering the pathogenic mutation to the offspring. Rapid changes in mtDNA heteroplasmy have been observed within a single generation, and so any ‘leakage’ of mutant mtDNA could lead to mtDNA disease in future generations, compromising the reproductive health of the first generation, and leading to repeated interventions in subsequent generations. To determine whether this is a real concern, we developed a model of mtDNA heteroplasmy inheritance by studying 87 mother–child pairs, and predicted the likely outcome of different levels of ‘mutant mtDNA leakage’ on subsequent maternal generations. This showed that, for a clinical threshold of 60%, reducing the proportion of mutant mtDNA to <5% dramatically reduces the chance of disease recurrence in subsequent generations, but transmitting >5% mutant mtDNA was associated with a significant chance of disease recurrence. Mutations with a lower clinical threshold were associated with a higher risk of recurrence. Our findings provide reassurance that, at least from an mtDNA perspective, methods currently under development have the potential to effectively eradicate pathogenic mtDNA mutations from subsequent generations.
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Affiliation(s)
- David C Samuels
- Department of Molecular Physiology and Biophysics, Center for Human Genetics Research, Vanderbilt University Medical Center, Nashville, TN, USA
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Pearce S, Nezich CL, Spinazzola A. Mitochondrial diseases: translation matters. Mol Cell Neurosci 2012; 55:1-12. [PMID: 22986124 DOI: 10.1016/j.mcn.2012.08.013] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2012] [Revised: 08/22/2012] [Accepted: 08/25/2012] [Indexed: 11/30/2022] Open
Abstract
Mitochondrial diseases comprise a heterogeneous group of disorders characterized by compromised energy production. Since the early days of mitochondrial medical genetics, it has been known that these can be caused by defects in mitochondrial protein synthesis. However, only in recent years have we begun to develop a broader picture of the array of proteins required for mitochondrial translation. With this new knowledge has come the realization that there are many more neurological and other, diseases attributable to impaired mitochondrial translation than previously thought. Perturbation of any part of this intricate machinery, from the primary sequence of transfer or ribosomal RNAs, to the proteolytic processing of ribosomal proteins, can cause mitochondrial dysfunction and disease. In this review we discuss the current understanding of the mechanisms and factors involved in mammalian mitochondrial translation, and the diverse pathologies resulting when it malfunctions. This article is part of a Special Issue entitled 'Mitochondrial function and dysfunction in neurodegeneration'.
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Affiliation(s)
- Sarah Pearce
- MRC Mitochondrial Biology Unit, Wellcome Trust-MRC Building, Hills Road Cambridge, CB2 0XY, UK
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34
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Mitochondrial disorders. Neurogenetics 2012. [DOI: 10.1017/cbo9781139087711.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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35
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Manipulation of mtDNA heteroplasmy in all striated muscles of newborn mice by AAV9-mediated delivery of a mitochondria-targeted restriction endonuclease. Gene Ther 2011; 19:1101-6. [PMID: 22130448 PMCID: PMC3410960 DOI: 10.1038/gt.2011.196] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Mitochondrial diseases are frequently caused by heteroplasmic mtDNA mutations. Because these mutations express themselves only at high relative ratios, any approach able to manipulate mtDNA heteroplasmy can potentially be curative. In this study we developed a system to manipulate mtDNA heteroplasmy in all skeletal muscles from neonate mice. We selected muscle because it is one of the most clinically affected tissues in mitochondrial disorders. A mitochondria targeted restriction endonuclease (mito-ApaLI) expressed from AAV9 particles was delivered either by intraperitoneal or intravenous injection in neonate mice harboring two mtDNA haplotypes, only one of which was susceptible to ApaLI digestion. A single injection was able to elicit a predictable and marked change in mtDNA heteroplasmy in all striated muscles analyzed, including heart. No health problems or reduction in mtDNA levels were observed in treated mice, suggesting that this approach could have clinical applications for mitochondrial myopathies.
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36
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Chiaratti MR, Meirelles FV, Wells D, Poulton J. Therapeutic treatments of mtDNA diseases at the earliest stages of human development. Mitochondrion 2011; 11:820-8. [DOI: 10.1016/j.mito.2010.11.004] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2010] [Accepted: 11/29/2010] [Indexed: 11/25/2022]
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37
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Fruhman G, Landsverk ML, Lotze TE, Hunter JV, Wangler MF, Adesina AM, Wong LJC, Scaglia F. Atypical presentation of Leigh syndrome associated with a Leber hereditary optic neuropathy primary mitochondrial DNA mutation. Mol Genet Metab 2011; 103:153-60. [PMID: 21414825 DOI: 10.1016/j.ymgme.2011.02.014] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2011] [Accepted: 02/21/2011] [Indexed: 10/18/2022]
Abstract
Leber hereditary optic neuropathy (LHON) is caused by point mutations in mitochondrial DNA (mtDNA), and is characterized by bilateral, painless sub-acute visual loss that develops during the second decade of life. Here we report the case of a five year old girl who presented with clinical and neuroradiological findings reminiscent of Leigh syndrome but carried a mtDNA mutation m.11778G>A (p.R340H) in the MTND4 gene usually observed in patients with LHON. This case is unusual for age of onset, gender, associated neurological findings and evolution, further expanding the clinical spectrum associated with primary LHON mtDNA mutations.
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MESH Headings
- Child, Preschool
- DNA, Mitochondrial/genetics
- Electron Transport Chain Complex Proteins/metabolism
- Female
- Gene Expression Regulation, Enzymologic
- Humans
- Leigh Disease/complications
- Leigh Disease/diagnosis
- Leigh Disease/genetics
- Leigh Disease/physiopathology
- Magnetic Resonance Imaging
- Magnetic Resonance Spectroscopy
- Muscle, Skeletal/enzymology
- Muscle, Skeletal/metabolism
- Mutation/genetics
- Optic Atrophy, Hereditary, Leber/complications
- Optic Atrophy, Hereditary, Leber/diagnosis
- Optic Atrophy, Hereditary, Leber/genetics
- Polymorphism, Genetic
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Affiliation(s)
- Gary Fruhman
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
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38
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Wenz T, Williams SL, Bacman SR, Moraes CT. Emerging therapeutic approaches to mitochondrial diseases. ACTA ACUST UNITED AC 2011; 16:219-29. [PMID: 20818736 DOI: 10.1002/ddrr.109] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Mitochondrial diseases are very heterogeneous and can affect different tissues and organs. Moreover, they can be caused by genetic defects in either nuclear or mitochondrial DNA as well as by environmental factors. All of these factors have made the development of therapies difficult. In this review article, we will discuss emerging approaches to the therapy of mitochondrial disorders, some of which are targeted to specific conditions whereas others may be applicable to a more diverse group of patients.
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Affiliation(s)
- Tina Wenz
- Department of Neurology, University of Miami School of Medicine, 1095 NW 14th Terrace, Miami, FL 33136, USA
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39
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Nesbitt V, Whittaker RG, Turnbull DM, McFarland R, Taylor RW. mtDNA disease for the neurologist. FUTURE NEUROLOGY 2011. [DOI: 10.2217/fnl.10.70] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Inherited and acquired mutations of mtDNA cause an extraordinary group of diseases that are associated with a diverse panoply of neurological and non-neurological features. These diseases are surprisingly common and are often severely debilitating and readily transmitted through families. Remarkable advances in understanding molecular mechanisms have been made since the first pathogenic mtDNA mutations were identified in 1988, and while widely available genetic techniques have facilitated diagnosis, the complexities of mitochondrial genetics leave the neurologist facing important challenges in recognizing, managing and counseling patients with mtDNA mutations. In this article, we will discuss the clinical phenotypes associated with mtDNA disease, current diagnostic strategies, disease management and genetic counseling, as well as presenting new developments in preventing disease transmission and secondary complications.
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Affiliation(s)
- Victoria Nesbitt
- Mitochondrial Research Group, Institute for Ageing & Health, The Medical School, Newcastle University, Framlington Place, Newcastle-upon-Tyne, NE2 4HH, UK
| | - Roger G Whittaker
- Mitochondrial Research Group, Institute for Ageing & Health, The Medical School, Newcastle University, Framlington Place, Newcastle-upon-Tyne, NE2 4HH, UK
| | - Douglass M Turnbull
- Mitochondrial Research Group, Institute for Ageing & Health, The Medical School, Newcastle University, Framlington Place, Newcastle-upon-Tyne, NE2 4HH, UK
| | - Robert McFarland
- Mitochondrial Research Group, Institute for Ageing & Health, The Medical School, Newcastle University, Framlington Place, Newcastle-upon-Tyne, NE2 4HH, UK
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Gelfand JM, Duncan JL, Racine CA, Gillum LA, Chin CT, Zhang Y, Zhang Q, Wong LJC, Roorda A, Green AJ. Heterogeneous patterns of tissue injury in NARP syndrome. J Neurol 2010; 258:440-8. [PMID: 20953793 PMCID: PMC3068520 DOI: 10.1007/s00415-010-5775-1] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2010] [Accepted: 09/23/2010] [Indexed: 11/18/2022]
Abstract
Point mutations at m.8993T>C and m.8993T>G of the mtDNA ATPase 6 gene cause the neurogenic weakness, ataxia and retinitis pigmentosa (NARP) syndrome, a mitochondrial disorder characterized by retinal, central and peripheral neurodegeneration. We performed detailed neurological, neuropsychological and ophthalmological phenotyping of a mother and four daughters with NARP syndrome from the mtDNA m.8993T>C ATPase 6 mutation, including 3-T brain MRI, spectral domain optical coherence tomography (SD-OCT), adaptive optics scanning laser ophthalmoscopy (AOSLO), electromyography and nerve conduction studies (EMG-NCS) and formal neuropsychological testing. The degree of mutant heteroplasmy for the m.8993T>C mutation was evaluated by real-time allele refractory mutation system quantitative PCR of mtDNA from hair bulbs (ectoderm) and blood leukocytes (mesoderm). There were marked phenotypic differences between family members, even between individuals with the greatest degrees of ectodermal and mesodermal heteroplasmy. 3-T MRI revealed cerebellar atrophy and cystic and cavitary T2 hyperintensities in the basal ganglia. SD-OCT demonstrated similarly heterogeneous areas of neuronal and axonal loss in inner and outer retinal layers. AOSLO showed increased cone spacing due to photoreceptor loss. EMG-NCS revealed varying degrees of length-dependent sensorimotor axonal polyneuropathy. On formal neuropsychological testing, there were varying deficits in processing speed, visual–spatial functioning and verbal fluency and high rates of severe depression. Many of these cognitive deficits likely localize to cerebellar and/or basal ganglia dysfunction. High-resolution retinal and brain imaging in NARP syndrome revealed analogous patterns of tissue injury characterized by heterogeneous areas of neuronal loss.
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Affiliation(s)
- Jeffrey M Gelfand
- Department of Neurology, University of California, San Francisco, CA 94143-0114, USA
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41
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Saneto RP, Naviaux RK. Polymerase gamma disease through the ages. ACTA ACUST UNITED AC 2010; 16:163-74. [DOI: 10.1002/ddrr.105] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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42
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Yoon YG, Koob MD, Yoo YH. Re-engineering the mitochondrial genomes in mammalian cells. Anat Cell Biol 2010; 43:97-109. [PMID: 21189990 PMCID: PMC2998782 DOI: 10.5115/acb.2010.43.2.97] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2010] [Revised: 05/20/2010] [Accepted: 05/25/2010] [Indexed: 02/04/2023] Open
Abstract
Mitochondria are subcellular organelles composed of two discrete membranes in the cytoplasm of eukaryotic cells. They have long been recognized as the generators of energy for the cell and also have been known to associate with several metabolic pathways that are crucial for cellular function. Mitochondria have their own genome, mitochondrial DNA (mtDNA), that is completely separated and independent from the much larger nuclear genome, and even have their own system for making proteins from the genes in this mtDNA genome. The human mtDNA is a small (~16.5 kb) circular DNA and defects in this genome can cause a wide range of inherited human diseases. Despite of the significant advances in discovering the mtDNA defects, however, there are currently no effective therapies for these clinically devastating diseases due to the lack of technology for introducing specific modifications into the mitochondrial genomes and for generating accurate mtDNA disease models. The ability to engineer the mitochondrial genomes would provide a powerful tool to create mutants with which many crucial experiments can be performed in the basic mammalian mitochondrial genetic studies as well as in the treatment of human mtDNA diseases. In this review we summarize the current approaches associated with the correction of mtDNA mutations in cells and describe our own efforts for introducing engineered mtDNA constructs into the mitochondria of living cells through bacterial conjugation.
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Affiliation(s)
- Young Geol Yoon
- Mitochondria Hub Regulation Center and Department of Anatomy and Cell Biology, Dong-A University, Busan, Korea
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43
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Seyedhassani SM, Houshmand M, Kalantar SM, Modabber G, Aflatoonian A. No mitochondrial DNA deletions but more D-loop point mutations in repeated pregnancy loss. J Assist Reprod Genet 2010; 27:641-8. [PMID: 20499271 DOI: 10.1007/s10815-010-9435-2] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2009] [Accepted: 05/06/2010] [Indexed: 01/14/2023] Open
Abstract
PURPOSE repeated pregnancy loss (RPL) occurs in 1 out of 300 couples, and the cause of about 50% of them remains idiopathic. Mitochondria have an important role in human development through ATP production and their involvement in apoptosis. METHODS 96 RPL and 96 control females were used to investigate the frequency of deletions and point mutations in the displacement loop (D-loop) on mitochondria. Multiplex PCR and DNA sequencing methods were used to detect possible variations in the mitochondrial DNA (mtDNA). RESULTS no deletions but a high frequency of point mutations were found in RPL females; among 129 variations observed in RPL, 22 mutations were significant (P < 0.05) and the insertion of C in nucleotide 114 was novel. CONCLUSION high rate of mutations in D-loop of mtDNA was observed in maternal blood, a fact that may have a direct or indirect role in inducing RPL. The results can be used in the assessment of RPL and designing possible treatments for improving assisted reproduction.
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44
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Wonnapinij P, Chinnery PF, Samuels DC. Previous estimates of mitochondrial DNA mutation level variance did not account for sampling error: comparing the mtDNA genetic bottleneck in mice and humans. Am J Hum Genet 2010; 86:540-50. [PMID: 20362273 DOI: 10.1016/j.ajhg.2010.02.023] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2009] [Revised: 02/16/2010] [Accepted: 02/23/2010] [Indexed: 12/12/2022] Open
Abstract
In cases of inherited pathogenic mitochondrial DNA (mtDNA) mutations, a mother and her offspring generally have large and seemingly random differences in the amount of mutated mtDNA that they carry. Comparisons of measured mtDNA mutation level variance values have become an important issue in determining the mechanisms that cause these large random shifts in mutation level. These variance measurements have been made with samples of quite modest size, which should be a source of concern because higher-order statistics, such as variance, are poorly estimated from small sample sizes. We have developed an analysis of the standard error of variance from a sample of size n, and we have defined error bars for variance measurements based on this standard error. We calculate variance error bars for several published sets of measurements of mtDNA mutation level variance and show how the addition of the error bars alters the interpretation of these experimental results. We compare variance measurements from human clinical data and from mouse models and show that the mutation level variance is clearly higher in the human data than it is in the mouse models at both the primary oocyte and offspring stages of inheritance. We discuss how the standard error of variance can be used in the design of experiments measuring mtDNA mutation level variance. Our results show that variance measurements based on fewer than 20 measurements are generally unreliable and ideally more than 50 measurements are required to reliably compare variances with less than a 2-fold difference.
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Affiliation(s)
- Passorn Wonnapinij
- Center of Human Genetics Research, Department of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, TN 37232, USA
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Bredenoord AL, Krumeich A, De Vries MC, Dondorp W, De Wert G. Reproductive decision-making in the context of mitochondrial DNA disorders: views and experiences of professionals. Clin Genet 2010; 77:10-7. [PMID: 20092587 DOI: 10.1111/j.1399-0004.2009.01312.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Although a scientific and ethical debate about the possible reproductive options for carriers of mitochondrial DNA (mtDNA) mutations is developing, not much information regarding the views and experiences of professionals exists. This paper explores the attitudes and experiences of professionals involved on a daily basis with their patients' reproductive decision-making in the context of mtDNA disease. Qualitative international multicenter design using in-depth semi-structured interviews with 20 professionals has been utilized. We identified four main themes emerging from the interviews. Firstly, we illustrate the discussion among professionals as to what extent mitochondrial genetics differs from other areas in genetics, both technically and ethically. Secondly, we show the discomfort and doubts of professionals when an mtDNA mutation is involved, because of the uncertainty remaining after testing. Thirdly, we discuss how professionals struggle with the tension between, on the one hand, the ideal of reproductive autonomy and, on the other hand, the reality of their professional responsibility and complex clinical decision-making. Fourthly, we delineate the strategies used by professionals in order to make attempts to control uncertainty. This paper illustrates the impact on professionals of reproductive decision-making in the context of mtDNA disease. It shows their feelings of discomfort when interpreting and explaining uncertain or ambiguous data and may be perceived as an example of how professionals deal with the inherent limitations in genetic knowledge representing the state of the art. Insight into the experiences of professionals may contribute to a further improvement of reproductive genetic counseling in the context of mtDNA disorders.
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Affiliation(s)
- A L Bredenoord
- Maastricht University, Faculty of Health, Medicine and Life Sciences, Health, Ethics & Society, Research Institutes GROW and CAPHRI, Maastricht, the Netherlands.
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Mitochondrial gene replacement in primate offspring and embryonic stem cells. Nature 2009; 461:367-72. [PMID: 19710649 PMCID: PMC2774772 DOI: 10.1038/nature08368] [Citation(s) in RCA: 364] [Impact Index Per Article: 24.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2009] [Accepted: 08/10/2009] [Indexed: 12/19/2022]
Abstract
Mitochondria are found in all eukaryotic cells and contain their own genome (mtDNA). Unlike the nuclear genome which is derived from both the egg and sperm at fertilization, the mtDNA in the embryo are derived almost exclusively from the egg, i.e. is of maternal origin. Mutations in mtDNA contribute to a diverse range of still incurable human diseases and disorders. To establish preclinical models for new therapeutic approaches, we demonstrate here that the mitochondrial genome can be efficiently replaced in mature nonhuman primate oocytes by spindle-chromosomal complex transfer from one egg to an enucleated, mitochondrial-replete egg. The reconstructed oocytes with the mitochondrial replacement were capable of supporting normal fertilization, embryo development and produced healthy offspring. Genetic analysis confirmed that nuclear DNA in the three infants born so far originated from the spindle donors while mtDNA came from the cytoplast donors. No contribution of spindle donor mtDNA was detected in offspring. Spindle replacement is shown here as an efficient protocol replacing the full complement of mitochondria in newly generated embryonic stem cell lines. This approach may offer a reproductive option to prevent mtDNA disease transmission in affected families.
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Kaare M, Götz A, Ulander VM, Ariansen S, Kaaja R, Suomalainen A, Aittomäki K. Do mitochondrial mutations cause recurrent miscarriage? Mol Hum Reprod 2009; 15:295-300. [PMID: 19297417 DOI: 10.1093/molehr/gap021] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The cause of recurrent miscarriage (RM) can be identified in approximately 50% of cases, whereas in others, unknown genetic factors are actively being sought. As mitochondrial functions, and therefore also the mitochondrial genome [mitochondrial DNA (mtDNA)], have an important role in human development, through ATP production and participation in apoptosis, we aimed to study the role of mtDNA variations in RM. We screened 48 women with RM and 48 age-matched control women for heteroplasmic mitochondrial mutations using denaturing high performance liquid chromatography, a sensitive method that can detect approximately 5% heteroplasmy. As a result, we detected a heteroplasmic mtDNA variation in 13 RM women (27%) and in 9 control women (19%). Seven synonymous and five non-synonymous changes were detected within coding regions. In addition, seven heteroplasmic variations were detected within the non-coding control region. We were also able to show the presence of the variations in eight placental samples from three heteroplasmic women. In three of these cases, the proportion of variant mtDNA was higher in the placenta compared with that in the mother. We conclude that our sensitive methodology revealed a higher frequency of samples with heteroplasmic variations than expected in women with both RM and controls. However, no apparent increased frequency of heteroplasmic mtDNA variations or amounts of aberrant mtDNA was detected in the RM group. In addition, none of the detected variations were previously known to be pathogenic and therefore they are an unlikely cause of miscarriage.
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Affiliation(s)
- Milja Kaare
- Folkhälsan Institute of Genetics, University of Helsinki, Helsinki, Finland.
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Sato A, Nakada K, Hayashi JI. Mitochondrial complementation preventing respiratory dysfunction caused by mutant mtDNA. Biofactors 2009; 35:130-7. [PMID: 19449440 DOI: 10.1002/biof.14] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The mitochondrial theory of aging is the idea that age-associated mitochondrial dysfunction is caused by accumulation of somatic mutations in mitochondrial DNA (mtDNA). However, mitochondria are considered to be a dynamic organelle that repeats fusion and fission. Through fusion and fission, there is an extensive and continuous exchange of mtDNA and its products between mitochondria. This mitochondrial complementation prevents individuals from expression of respiratory dysfunction caused by pathogenic mutant mtDNAs. Thus, the presence of mitochondrial complementation does not support the mitochondrial theory of aging. Moreover, the presence of mitochondrial complementation enables gene therapy for mitochondrial diseases using nuclear transplantation of zygotes. (c) 2009 International Union of Biochemistry and Molecular Biology, Inc.
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Affiliation(s)
- Akitsugu Sato
- Graduate School of Life and Environmental Sciences, University of Tsukuba, Ibaraki, Japan
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Abstract
Paediatric neurological disorders encompass a large group of clinically heterogeneous diseases, of which some are known to have a genetic cause. Over the past few years, advances in nosological classifications and in strategies for molecular testing have substantially improved the diagnosis, genetic counselling, and clinical management of many patients, and have facilitated the possibility of prenatal diagnoses for future pregnancies. However, the increasing availability of genetic tests for paediatric neurological disorders is raising important questions with regard to the appropriateness, choice of protocols, interpretation of results, and ethical and social concerns of these services. In this Review, we discuss these topics and how these concerns affect genetic counselling.
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