1
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Gao F, Schon KR, Vandrovcova J, Wilson L, Hanna MG, Çavdarlı B, Heckmann J, Chinnery PF, Horvath R. Mitochondrial DNA disorders in neuromuscular diseases in diverse populations. Ann Clin Transl Neurol 2024. [PMID: 39095335 DOI: 10.1002/acn3.52141] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2024] [Revised: 06/21/2024] [Accepted: 06/24/2024] [Indexed: 08/04/2024] Open
Abstract
Neuromuscular features are common in mitochondrial DNA (mtDNA) disorders. The genetic architecture of mtDNA disorders in diverse populations is poorly understood. We analysed mtDNA variants from whole-exome sequencing data in neuromuscular patients from South Africa, Brazil, India, Turkey and Zambia. In 998 individuals, there were two definite diagnoses, two possible diagnoses and eight secondary findings. Surprisingly, common pathogenic mtDNA variants found in people of European ancestry were very rare. Whole-exome or -genome sequencing from undiagnosed patients with neuromuscular symptoms should be re-analysed for mtDNA variants, but the landscape of pathogenic mtDNA variants differs around the world.
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Affiliation(s)
- Fei Gao
- Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
| | - Katherine R Schon
- Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
- MRC Mitochondrial Biology Unit, University of Cambridge, Cambridge, UK
- Academic Department of Medical Genetics, University of Cambridge, Cambridge, UK
| | - Jana Vandrovcova
- UCL Queen Square Institute of Neurology, University College London, London, UK
| | - Lindsay Wilson
- UCL Queen Square Institute of Neurology, University College London, London, UK
| | - Michael G Hanna
- UCL Queen Square Institute of Neurology, University College London, London, UK
| | - Büşranur Çavdarlı
- Department of Medical Genetics, Ankara Bilkent City Hospital, Ankara, Turkey
- Faculty of Medicine, Department of Medical Genetics, Ankara Yıldırım Beyazıt University, Ankara, Turkey
| | - Jeannine Heckmann
- Neuroscience Institute, University of Cape Town, Cape Town, South Africa
- Division of Neurology, Department of Medicine, Groote Schuur Hospital, Cape Town, South Africa
| | - Patrick F Chinnery
- Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
- MRC Mitochondrial Biology Unit, University of Cambridge, Cambridge, UK
| | - Rita Horvath
- Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
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2
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Das J, Bhattacharjee S, Saha S. mitoPADdb: A database of mitochondrial proteins associated with diseases. Mitochondrion 2024; 78:101927. [PMID: 38944368 DOI: 10.1016/j.mito.2024.101927] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2024] [Revised: 06/04/2024] [Accepted: 06/26/2024] [Indexed: 07/01/2024]
Abstract
Mitochondrial protein/gene mutations and expression variations contribute to the pathogenesis of various diseases, such as neurodegenerative and metabolic diseases. Detailed studies on mitochondrial protein-encoding (MPE) genes across diseases can provide clues for novel therapeutic strategies. Here, we collected, compiled, and manually curated the MPE gene mutation and expression variations data and their association with diseases in a single platform named mitoPADdb. The database contains 810 genes with 18,356 mutations and 1284 qualitative expression variations associated with 1793 diseases, grouped into 15 categories. It allows users to perform a comparative quantitative gene expression analysis for 317 transcriptomic studies across disease categories. Further, it provides information on MPE genes-associated molecular pathways. The mitoPADdb is a valuable resource for investigating mitochondrial dysfunction-related diseases. It can be accessed via http://bicresources.jcbose.ac.in/ssaha4/mitopaddb/index.html.
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Affiliation(s)
- Jagannath Das
- Department of Biological Sciences, Bose Institute, Kolkata, 700091, India
| | - Sudipto Bhattacharjee
- Department of Computer Science and Engineering, University of Calcutta, Kolkata, 700098, India
| | - Sudipto Saha
- Department of Biological Sciences, Bose Institute, Kolkata, 700091, India.
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3
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Ratnaike TE, Elkhateeb N, Lochmüller A, Gilmartin C, Schon K, Horváth R, Chinnery PF. Evidence for sodium valproate toxicity in mitochondrial diseases: a systematic analysis. BMJ Neurol Open 2024; 6:e000650. [PMID: 38860231 PMCID: PMC11163645 DOI: 10.1136/bmjno-2024-000650] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2024] [Accepted: 04/14/2024] [Indexed: 06/12/2024] Open
Abstract
Background We aimed to determine whether sodium valproate (VPA) should be contraindicated in all mitochondrial diseases, due to known VPA-induced severe hepatotoxicity in some mitochondrial diseases. Methods We systematically reviewed the published literature for mitochondrial DNA (mtDNA) and common nuclear genotypes of mitochondrial diseases using PubMed, Ovid Embase, Ovid Medline and MitoPhen databases. We extracted patient-level data from peer-reviewed articles, published until July 2022, using the Human Phenotype Ontology to manually code clinical presentations for 156 patients with genetic diagnoses from 90 publications. Results There were no fatal adverse drug reactions (ADRs) in the mtDNA disease group (35 patients), and only 1 out of 54 patients with a non-POLG mitochondrial disease developed acute liver failure. There were fatal outcomes in 53/102 (52%) POLG VPA-exposed patients who all harboured recessive mutations. Conclusions Our findings confirm the high risk of severe ADRs in any patient with recessive POLG variants irrespective of the phenotype, and therefore recommend that VPA is contraindicated in this group. However, there was limited evidence of toxicity to support a similar recommendation in other genotypes of mitochondrial diseases.
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Affiliation(s)
- Thiloka E Ratnaike
- Department of Paediatrics, University of Cambridge, Cambridge, UK
- Department of Paediatrics, Colchester Hospital University NHS Foundation Trust, Colchester, UK
| | - Nour Elkhateeb
- Department of Clinical Genetics, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK
| | - Angela Lochmüller
- Department of Medical Genetics, Cambridge Biomedical Campus, Cambridge, UK
- University College London Hospitals NHS Foundation Trust, London, UK
| | - Christopher Gilmartin
- Department of Medical Genetics, Cambridge Biomedical Campus, Cambridge, UK
- University of Nottingham, Nottingham, UK
| | - Katherine Schon
- Department of Clinical Genetics, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK
- Cambridge Biomedical Campus Department of Clinical Neurosciences, University of Cambridge, Cambridge, Cambridgeshire, UK
| | - Rita Horváth
- Cambridge Biomedical Campus Department of Clinical Neurosciences, University of Cambridge, Cambridge, Cambridgeshire, UK
| | - Patrick F Chinnery
- Cambridge Biomedical Campus Department of Clinical Neurosciences, University of Cambridge, Cambridge, Cambridgeshire, UK
- Medical Research Council Mitochondrial Biology Unit, Cambridge Biomedical Campus, Cambridge, UK
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4
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Kanazashi Y, Maejima K, Johnson TA, Sasagawa S, Jikuya R, Hasumi H, Matsumoto N, Maekawa S, Obara W, Nakagawa H. Mitochondrial DNA Variants at Low-Level Heteroplasmy and Decreased Copy Numbers in Chronic Kidney Disease (CKD) Tissues with Kidney Cancer. Int J Mol Sci 2023; 24:17212. [PMID: 38139039 PMCID: PMC10743237 DOI: 10.3390/ijms242417212] [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: 09/13/2023] [Revised: 11/28/2023] [Accepted: 11/30/2023] [Indexed: 12/24/2023] Open
Abstract
The human mitochondrial genome (mtDNA) is a circular DNA molecule with a length of 16.6 kb, which contains a total of 37 genes. Somatic mtDNA mutations accumulate with age and environmental exposure, and some types of mtDNA variants may play a role in carcinogenesis. Recent studies observed mtDNA variants not only in kidney tumors but also in adjacent kidney tissues, and mtDNA dysfunction results in kidney injury, including chronic kidney disease (CKD). To investigate whether a relationship exists between heteroplasmic mtDNA variants and kidney function, we performed ultra-deep sequencing (30,000×) based on long-range PCR of DNA from 77 non-tumor kidney tissues of kidney cancer patients with CKD (stages G1 to G5). In total, this analysis detected 697 single-nucleotide variants (SNVs) and 504 indels as heteroplasmic (0.5% ≤ variant allele frequency (VAF) < 95%), and the total number of detected SNVs/indels did not differ between CKD stages. However, the number of deleterious low-level heteroplasmic variants (pathogenic missense, nonsense, frameshift and tRNA) significantly increased with CKD progression (p < 0.01). In addition, mtDNA copy numbers (mtDNA-CNs) decreased with CKD progression (p < 0.001). This study demonstrates that mtDNA damage, which affects mitochondrial genes, may be involved in reductions in mitochondrial mass and associated with CKD progression and kidney dysfunction.
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Affiliation(s)
- Yuki Kanazashi
- Laboratory for Cancer Genomics, RIKEN Center for Integrative Medical Sciences, Yokohama 230-0045, Japan; (Y.K.); (K.M.); (T.A.J.); (S.S.)
- Department of Human Genetics, Yokohama City University, Yokohama 236-0004, Japan;
| | - Kazuhiro Maejima
- Laboratory for Cancer Genomics, RIKEN Center for Integrative Medical Sciences, Yokohama 230-0045, Japan; (Y.K.); (K.M.); (T.A.J.); (S.S.)
| | - Todd A. Johnson
- Laboratory for Cancer Genomics, RIKEN Center for Integrative Medical Sciences, Yokohama 230-0045, Japan; (Y.K.); (K.M.); (T.A.J.); (S.S.)
| | - Shota Sasagawa
- Laboratory for Cancer Genomics, RIKEN Center for Integrative Medical Sciences, Yokohama 230-0045, Japan; (Y.K.); (K.M.); (T.A.J.); (S.S.)
| | - Ryosuke Jikuya
- Department of Urology, Yokohama City University, Yokohama 236-0004, Japan; (R.J.); (H.H.)
| | - Hisashi Hasumi
- Department of Urology, Yokohama City University, Yokohama 236-0004, Japan; (R.J.); (H.H.)
| | - Naomichi Matsumoto
- Department of Human Genetics, Yokohama City University, Yokohama 236-0004, Japan;
| | - Shigekatsu Maekawa
- Department of Urology, Iwate Medical University, Iwate 028-3694, Japan; (S.M.); (W.O.)
| | - Wataru Obara
- Department of Urology, Iwate Medical University, Iwate 028-3694, Japan; (S.M.); (W.O.)
| | - Hidewaki Nakagawa
- Laboratory for Cancer Genomics, RIKEN Center for Integrative Medical Sciences, Yokohama 230-0045, Japan; (Y.K.); (K.M.); (T.A.J.); (S.S.)
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5
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Hathazi D, Horvath R. Mitochondrial DNA editing with mitoARCUS. Nat Metab 2023; 5:2039-2040. [PMID: 38036769 DOI: 10.1038/s42255-023-00933-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/02/2023]
Affiliation(s)
- Denisa Hathazi
- Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
| | - Rita Horvath
- Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK.
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6
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Chen X, Chen M, Zhu Y, Sun H, Wang Y, Xie Y, Ji L, Wang C, Hu Z, Guo X, Xu Z, Zhang J, Yang S, Liang D, Shen B. Correction of a homoplasmic mitochondrial tRNA mutation in patient-derived iPSCs via a mitochondrial base editor. Commun Biol 2023; 6:1116. [PMID: 37923818 PMCID: PMC10624837 DOI: 10.1038/s42003-023-05500-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2023] [Accepted: 10/24/2023] [Indexed: 11/06/2023] Open
Abstract
Pathogenic mutations in mitochondrial DNA cause severe and often lethal multi-system symptoms in primary mitochondrial defects. However, effective therapies for these defects are still lacking. Strategies such as employing mitochondrially targeted restriction enzymes or programmable nucleases to shift the ratio of heteroplasmic mutations and allotopic expression of mitochondrial protein-coding genes have limitations in treating mitochondrial homoplasmic mutations, especially in non-coding genes. Here, we conduct a proof of concept study applying a screened DdCBE pair to correct the homoplasmic m.A4300G mutation in induced pluripotent stem cells derived from a patient with hypertrophic cardiomyopathy. We achieve efficient G4300A correction with limited off-target editing, and successfully restore mitochondrial function in corrected induced pluripotent stem cell clones. Our study demonstrates the feasibility of using DdCBE to treat primary mitochondrial defects caused by homoplasmic pathogenic mitochondrial DNA mutations.
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Affiliation(s)
- Xiaoxu Chen
- State Key Laboratory of Reproductive Medicine and Offspring Health, Women's Hospital of Nanjing Medical University, Nanjing Maternity and Child Health Care Hospital, Gusu School, Nanjing Medical University, Nanjing, 211166, China
| | - Mingyue Chen
- State Key Laboratory of Reproductive Medicine and Offspring Health, Women's Hospital of Nanjing Medical University, Nanjing Maternity and Child Health Care Hospital, Gusu School, Nanjing Medical University, Nanjing, 211166, China
| | - Yuqing Zhu
- Department of Prenatal Diagnosis, Women's Hospital of Nanjing Medical University, Nanjing Maternity and Child Health Care Hospital, Nanjing, 210004, China
| | - Haifeng Sun
- State Key Laboratory of Reproductive Medicine and Offspring Health, Women's Hospital of Nanjing Medical University, Nanjing Maternity and Child Health Care Hospital, Gusu School, Nanjing Medical University, Nanjing, 211166, China
| | - Yue Wang
- State Key Laboratory of Reproductive Medicine, Department of Histology and Embryology, Nanjing Medical University, Nanjing, 211166, China
| | - Yuan Xie
- Department of Bioinformatics, School of Biomedical Engineering and Informatics, Nanjing Medical University, Nanjing, 211166, China
| | - Lianfu Ji
- Department of Cardiology, Children's Hospital of Nanjing Medical University, Nanjing, 210008, China
| | - Cheng Wang
- Department of Bioinformatics, School of Biomedical Engineering and Informatics, Nanjing Medical University, Nanjing, 211166, China
| | - Zhibin Hu
- Department of Epidemiology, Center for Global Health, School of Public Health, Nanjing Medical University, Nanjing, 211166, China
| | - Xuejiang Guo
- State Key Laboratory of Reproductive Medicine, Department of Histology and Embryology, Nanjing Medical University, Nanjing, 211166, China
| | - Zhengfeng Xu
- Department of Prenatal Diagnosis, Women's Hospital of Nanjing Medical University, Nanjing Maternity and Child Health Care Hospital, Nanjing, 210004, China.
| | - Jun Zhang
- State Key Laboratory of Reproductive Medicine and Offspring Health, Women's Hospital of Nanjing Medical University, Nanjing Maternity and Child Health Care Hospital, Gusu School, Nanjing Medical University, Nanjing, 211166, China.
| | - Shiwei Yang
- Department of Cardiology, Children's Hospital of Nanjing Medical University, Nanjing, 210008, China.
| | - Dong Liang
- Department of Prenatal Diagnosis, Women's Hospital of Nanjing Medical University, Nanjing Maternity and Child Health Care Hospital, Nanjing, 210004, China.
| | - Bin Shen
- State Key Laboratory of Reproductive Medicine and Offspring Health, Women's Hospital of Nanjing Medical University, Nanjing Maternity and Child Health Care Hospital, Gusu School, Nanjing Medical University, Nanjing, 211166, China.
- Department of Epidemiology, Center for Global Health, School of Public Health, Nanjing Medical University, Nanjing, 211166, China.
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7
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Skoczylas S, Jakiel P, Płoszaj T, Gadzalska K, Borowiec M, Pastorczak A, Moczulska H, Malarska M, Eckersdorf-Mastalerz A, Budzyńska E, Zmysłowska A. Novel potentially pathogenic variants detected in genes causing intellectual disability and epilepsy in Polish families. Neurogenetics 2023; 24:221-229. [PMID: 37405542 PMCID: PMC10545623 DOI: 10.1007/s10048-023-00724-w] [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: 05/25/2023] [Accepted: 06/27/2023] [Indexed: 07/06/2023]
Abstract
BACKGROUND Intellectual disability (ID) affects 1-3% of the world population. The number of genes whose dysfunctions cause intellectual disability is increasing. In addition, new gene associations are constantly being discovered, as well as specific phenotypic features for already identified genetic alterations are being described. The aim of our study was to search for pathogenic variants in genes responsible for moderate to severe intellectual disability and epilepsy, using a panel of targeted next-generation sequencing (tNGS) for diagnosis. METHODS The group of 73 patients (ID, n=32; epilepsy, n=21; ID and epilepsy, n=18) was enrolled in the nucleus DNA (nuDNA) study using a tNGS panel (Agilent Technologies, USA). In addition, high coverage mitochondrial DNA (mtDNA) was extracted from the tNGS data for 54 patients. RESULTS Fifty-two rare nuDNA variants, as well as 10 rare and 1 novel mtDNA variants, were found in patients in the study group. The 10 most damaging nuDNA variants were subjected to a detailed clinical analysis. Finally, 7 nuDNA and 1 mtDNA were found to be the cause of the disease. CONCLUSIONS This shows that still a very large proportion of patients remain undiagnosed and may require further testing. The reason for the negative results of our analysis may be a non-genetic cause of the observed phenotypes or failure to detect the causative variant in the genome. In addition, the study clearly shows that analysis of the mtDNA genome is clinically relevant, as approximately 1% of patients with ID may have pathogenic variant in mitochondrial DNA.
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Affiliation(s)
- S Skoczylas
- 1Department of Clinical Genetics, Medical University of Lodz, Lodz, Poland.
| | - P Jakiel
- 1Department of Clinical Genetics, Medical University of Lodz, Lodz, Poland
| | - T Płoszaj
- 1Department of Clinical Genetics, Medical University of Lodz, Lodz, Poland
| | - K Gadzalska
- 1Department of Clinical Genetics, Medical University of Lodz, Lodz, Poland
| | - M Borowiec
- 1Department of Clinical Genetics, Medical University of Lodz, Lodz, Poland
| | - A Pastorczak
- 1Department of Clinical Genetics, Medical University of Lodz, Lodz, Poland
| | - H Moczulska
- 1Department of Clinical Genetics, Medical University of Lodz, Lodz, Poland
| | - M Malarska
- 1Department of Clinical Genetics, Medical University of Lodz, Lodz, Poland
| | | | - E Budzyńska
- 1Department of Clinical Genetics, Medical University of Lodz, Lodz, Poland
| | - A Zmysłowska
- 1Department of Clinical Genetics, Medical University of Lodz, Lodz, Poland
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8
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Gupta R, Kanai M, Durham TJ, Tsuo K, McCoy JG, Kotrys AV, Zhou W, Chinnery PF, Karczewski KJ, Calvo SE, Neale BM, Mootha VK. Nuclear genetic control of mtDNA copy number and heteroplasmy in humans. Nature 2023; 620:839-848. [PMID: 37587338 PMCID: PMC10447254 DOI: 10.1038/s41586-023-06426-5] [Citation(s) in RCA: 30] [Impact Index Per Article: 30.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2022] [Accepted: 07/11/2023] [Indexed: 08/18/2023]
Abstract
Mitochondrial DNA (mtDNA) is a maternally inherited, high-copy-number genome required for oxidative phosphorylation1. Heteroplasmy refers to the presence of a mixture of mtDNA alleles in an individual and has been associated with disease and ageing. Mechanisms underlying common variation in human heteroplasmy, and the influence of the nuclear genome on this variation, remain insufficiently explored. Here we quantify mtDNA copy number (mtCN) and heteroplasmy using blood-derived whole-genome sequences from 274,832 individuals and perform genome-wide association studies to identify associated nuclear loci. Following blood cell composition correction, we find that mtCN declines linearly with age and is associated with variants at 92 nuclear loci. We observe that nearly everyone harbours heteroplasmic mtDNA variants obeying two principles: (1) heteroplasmic single nucleotide variants tend to arise somatically and accumulate sharply after the age of 70 years, whereas (2) heteroplasmic indels are maternally inherited as mixtures with relative levels associated with 42 nuclear loci involved in mtDNA replication, maintenance and novel pathways. These loci may act by conferring a replicative advantage to certain mtDNA alleles. As an illustrative example, we identify a length variant carried by more than 50% of humans at position chrM:302 within a G-quadruplex previously proposed to mediate mtDNA transcription/replication switching2,3. We find that this variant exerts cis-acting genetic control over mtDNA abundance and is itself associated in-trans with nuclear loci encoding machinery for this regulatory switch. Our study suggests that common variation in the nuclear genome can shape variation in mtCN and heteroplasmy dynamics across the human population.
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Affiliation(s)
- Rahul Gupta
- Howard Hughes Medical Institute and Department of Molecular Biology, Massachusetts General Hospital, Boston, MA, USA.
- Broad Institute of MIT and Harvard, Cambridge, MA, USA.
- Analytic and Translational Genetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA.
| | - Masahiro Kanai
- Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Analytic and Translational Genetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA
| | - Timothy J Durham
- Howard Hughes Medical Institute and Department of Molecular Biology, Massachusetts General Hospital, Boston, MA, USA
- Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Kristin Tsuo
- Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Analytic and Translational Genetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA
| | - Jason G McCoy
- Howard Hughes Medical Institute and Department of Molecular Biology, Massachusetts General Hospital, Boston, MA, USA
- Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Anna V Kotrys
- Howard Hughes Medical Institute and Department of Molecular Biology, Massachusetts General Hospital, Boston, MA, USA
- Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Wei Zhou
- Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Analytic and Translational Genetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA
| | - Patrick F Chinnery
- Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
- MRC Mitochondrial Biology Unit, University of Cambridge, Cambridge, UK
| | - Konrad J Karczewski
- Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Analytic and Translational Genetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA
| | - Sarah E Calvo
- Howard Hughes Medical Institute and Department of Molecular Biology, Massachusetts General Hospital, Boston, MA, USA
- Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Benjamin M Neale
- Broad Institute of MIT and Harvard, Cambridge, MA, USA.
- Analytic and Translational Genetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA.
| | - Vamsi K Mootha
- Howard Hughes Medical Institute and Department of Molecular Biology, Massachusetts General Hospital, Boston, MA, USA.
- Broad Institute of MIT and Harvard, Cambridge, MA, USA.
- Department of Systems Biology, Harvard Medical School, Boston, MA, USA.
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9
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Chinnery PF. Mitochondrial disease in neurology-Past, present, and future. HANDBOOK OF CLINICAL NEUROLOGY 2023; 194:3-6. [PMID: 36813319 DOI: 10.1016/b978-0-12-821751-1.00001-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/22/2023]
Abstract
This chapter provides a overview of this volume of the Handbook of Clinical Neurology, placing recent advances in our understanding of mitochondrial disorders in a historical context, and speculates about the future.
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Affiliation(s)
- Patrick F Chinnery
- Department of Clinical Neurosciences & MRC Mitochondrial Biology Unit, University of Cambridge, Cambridge, United Kingdom.
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10
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Gupta R, Kanai M, Durham TJ, Tsuo K, McCoy JG, Chinnery PF, Karczewski KJ, Calvo SE, Neale BM, Mootha VK. Nuclear genetic control of mtDNA copy number and heteroplasmy in humans. MEDRXIV : THE PREPRINT SERVER FOR HEALTH SCIENCES 2023:2023.01.19.23284696. [PMID: 36711677 PMCID: PMC9882621 DOI: 10.1101/2023.01.19.23284696] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Human mitochondria contain a high copy number, maternally transmitted genome (mtDNA) that encodes 13 proteins required for oxidative phosphorylation. Heteroplasmy arises when multiple mtDNA variants co-exist in an individual and can exhibit complex dynamics in disease and in aging. As all proteins involved in mtDNA replication and maintenance are nuclear-encoded, heteroplasmy levels can, in principle, be under nuclear genetic control, however this has never been shown in humans. Here, we develop algorithms to quantify mtDNA copy number (mtCN) and heteroplasmy levels using blood-derived whole genome sequences from 274,832 individuals of diverse ancestry and perform GWAS to identify nuclear loci controlling these traits. After careful correction for blood cell composition, we observe that mtCN declines linearly with age and is associated with 92 independent nuclear genetic loci. We find that nearly every individual carries heteroplasmic variants that obey two key patterns: (1) heteroplasmic single nucleotide variants are somatic mutations that accumulate sharply after age 70, while (2) heteroplasmic indels are maternally transmitted as mtDNA mixtures with resulting levels influenced by 42 independent nuclear loci involved in mtDNA replication, maintenance, and novel pathways. These nuclear loci do not appear to act by mtDNA mutagenesis, but rather, likely act by conferring a replicative advantage to specific mtDNA molecules. As an illustrative example, the most common heteroplasmy we identify is a length variant carried by >50% of humans at position m.302 within a G-quadruplex known to serve as a replication switch. We find that this heteroplasmic variant exerts cis -acting genetic control over mtDNA abundance and is itself under trans -acting genetic control of nuclear loci encoding protein components of this regulatory switch. Our study showcases how nuclear haplotype can privilege the replication of specific mtDNA molecules to shape mtCN and heteroplasmy dynamics in the human population.
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Affiliation(s)
- Rahul Gupta
- Howard Hughes Medical Institute and Department of Molecular Biology, Massachusetts General Hospital, United States
- Broad Institute of MIT and Harvard, United States
- Analytic and Translational Genetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, United States
| | - Masahiro Kanai
- Broad Institute of MIT and Harvard, United States
- Analytic and Translational Genetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, United States
| | - Timothy J Durham
- Howard Hughes Medical Institute and Department of Molecular Biology, Massachusetts General Hospital, United States
- Broad Institute of MIT and Harvard, United States
| | - Kristin Tsuo
- Broad Institute of MIT and Harvard, United States
- Analytic and Translational Genetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, United States
| | - Jason G McCoy
- Howard Hughes Medical Institute and Department of Molecular Biology, Massachusetts General Hospital, United States
- Broad Institute of MIT and Harvard, United States
| | - Patrick F Chinnery
- Department of Clinical Neurosciences & MRC Mitochondrial Biology Unit, University of Cambridge, United Kingdom
| | - Konrad J Karczewski
- Broad Institute of MIT and Harvard, United States
- Analytic and Translational Genetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, United States
| | - Sarah E Calvo
- Howard Hughes Medical Institute and Department of Molecular Biology, Massachusetts General Hospital, United States
- Broad Institute of MIT and Harvard, United States
| | - Benjamin M Neale
- Broad Institute of MIT and Harvard, United States
- Analytic and Translational Genetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, United States
| | - Vamsi K Mootha
- Howard Hughes Medical Institute and Department of Molecular Biology, Massachusetts General Hospital, United States
- Broad Institute of MIT and Harvard, United States
- Department of Systems Biology, Harvard Medical School, United States
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11
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Alkhaldi HA, Phan DH, Vik SB. Analysis of Human Clinical Mutations of Mitochondrial ND1 in a Bacterial Model System for Complex I. Life (Basel) 2022; 12:1934. [PMID: 36431069 PMCID: PMC9696053 DOI: 10.3390/life12111934] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Revised: 11/13/2022] [Accepted: 11/17/2022] [Indexed: 11/22/2022] Open
Abstract
The most common causes of mitochondrial dysfunction and disease include mutations in subunits and assembly factors of Complex I. Numerous mutations in the mitochondrial gene ND1 have been identified in humans. Currently, a bacterial model system provides the only method for rapid construction and analysis of mutations in homologs of human ND1. In this report, we have identified nine mutations in human ND1 that are reported to be pathogenic and are located at subunit interfaces. Our hypothesis was that these mutations would disrupt Complex I assembly. Seventeen mutations were constructed in the homologous nuoH gene in an E. coli model system. In addition to the clinical mutations, alanine substitutions were constructed in order to distinguish between a deleterious effect from the introduction of the mutant residue and the loss of the original residue. The mutations were moved to an expression vector containing all thirteen genes of the E. coli nuo operon coding for Complex I. Membrane vesicles were prepared and rates of deamino-NADH oxidase activity and proton translocation were measured. Samples were also tested for assembly by native gel electrophoresis and for expression of NuoH by immunoblotting. A range of outcomes was observed: Mutations at four of the sites allow normal assembly with moderate activity (50−76% of wild type). Mutations at the other sites disrupt assembly and/or activity, and in some cases the outcomes depend upon the amino acid introduced. In general, the outcomes are consistent with the proposed pathogenicity in humans.
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Affiliation(s)
| | | | - Steven B. Vik
- Department of Biological Sciences, Southern Methodist University, Dallas, TX 75275, USA
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12
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Mok YG, Lee JM, Chung E, Lee J, Lim K, Cho SI, Kim JS. Base editing in human cells with monomeric DddA-TALE fusion deaminases. Nat Commun 2022; 13:4038. [PMID: 35821233 PMCID: PMC9276701 DOI: 10.1038/s41467-022-31745-y] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Accepted: 06/29/2022] [Indexed: 11/09/2022] Open
Abstract
Inter-bacterial toxin DddA-derived cytosine base editors (DdCBEs) enable targeted C-to-T conversions in nuclear and organellar DNA. DddAtox, the deaminase catalytic domain derived from Burkholderia cenocepacia, is split into two inactive halves to avoid its cytotoxicity in eukaryotic cells, when fused to transcription activator-like effector (TALE) DNA-binding proteins to make DdCBEs. As a result, DdCBEs function as pairs, which hampers gene delivery via viral vectors with a small cargo size. Here, we present non-toxic, full-length DddAtox variants to make monomeric DdCBEs (mDdCBEs), enabling mitochondrial DNA editing with high efficiencies of up to 50%, when transiently expressed in human cells. We demonstrate that mDdCBEs expressed via AAV in cultured human cells can achieve nearly homoplasmic C-to-T editing in mitochondrial DNA. Interestingly, mDdCBEs often produce mutation patterns different from those obtained with conventional dimeric DdCBEs. Furthermore, mDdCBEs allow base editing at sites for which only one TALE protein can be designed. We also show that transfection of mDdCBE-encoding mRNA, rather than plasmid, can reduce off-target editing in human mitochondrial DNA.
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Affiliation(s)
- Young Geun Mok
- Center for Genome Engineering, Institute for Basic Science, Daejeon, Republic of Korea
| | - Ji Min Lee
- Center for Genome Engineering, Institute for Basic Science, Daejeon, Republic of Korea.,Department of Chemistry, Seoul National University, Seoul, Republic of Korea
| | - Eugene Chung
- Center for Genome Engineering, Institute for Basic Science, Daejeon, Republic of Korea.,Department of Chemistry, Seoul National University, Seoul, Republic of Korea
| | - Jaesuk Lee
- Center for Genome Engineering, Institute for Basic Science, Daejeon, Republic of Korea.,Department of Chemistry, Seoul National University, Seoul, Republic of Korea
| | - Kayeong Lim
- Center for Genome Engineering, Institute for Basic Science, Daejeon, Republic of Korea
| | - Sung-Ik Cho
- Center for Genome Engineering, Institute for Basic Science, Daejeon, Republic of Korea.,Department of Chemistry, Seoul National University, Seoul, Republic of Korea
| | - Jin-Soo Kim
- Center for Genome Engineering, Institute for Basic Science, Daejeon, Republic of Korea.
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Silva-Pinheiro P, Minczuk M. The potential of mitochondrial genome engineering. Nat Rev Genet 2022; 23:199-214. [PMID: 34857922 DOI: 10.1038/s41576-021-00432-x] [Citation(s) in RCA: 58] [Impact Index Per Article: 29.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/26/2021] [Indexed: 12/19/2022]
Abstract
Mitochondria are subject to unique genetic control by both nuclear DNA and their own genome, mitochondrial DNA (mtDNA), of which each mitochondrion contains multiple copies. In humans, mutations in mtDNA can lead to devastating, heritable, multi-system diseases that display different tissue-specific presentation at any stage of life. Despite rapid advances in nuclear genome engineering, for years, mammalian mtDNA has remained resistant to genetic manipulation, hampering our ability to understand the mechanisms that underpin mitochondrial disease. Recent developments in the genetic modification of mammalian mtDNA raise the possibility of using genome editing technologies, such as programmable nucleases and base editors, for the treatment of hereditary mitochondrial disease.
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Affiliation(s)
| | - Michal Minczuk
- MRC Mitochondrial Biology Unit, University of Cambridge, Cambridge, UK.
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14
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Zhang F, Dang QCL, Vik SB. Human clinical mutations in mitochondrially encoded subunits of Complex I can be successfully modeled in E. coli. Mitochondrion 2022; 64:59-72. [PMID: 35306226 PMCID: PMC9035099 DOI: 10.1016/j.mito.2022.03.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Revised: 02/21/2022] [Accepted: 03/15/2022] [Indexed: 11/28/2022]
Abstract
Respiratory Complex I is the site of a large fraction of the mutations that appear to cause mitochondrial disease. Seven of its subunits are mitochondrially encoded, and therefore, such mutants are particularly difficult to construct in cell-culture model systems. We have selected 13 human clinical mutations found in ND2, ND3, ND4, ND4L, ND5 and ND6 that are generally found at subunit interfaces, and not in critical residues. These mutations have been modeled in E. coli subunits of Complex I, nuoN, nuoA, nuoM, nuoK, nuoL, and nuoJ, respectively. All mutants were expressed from a plasmid encoding the entire nuo operon, and membrane vesicles were analyzed for deamino-NADH oxidase activity, and proton translocation activity. ND5 mutants were also analyzed using a time-delayed expression system, recently described by this lab. Other mutants were analyzed for the ability to associate in subcomplexes, after expression of subsets of the genes. For most mutants there was a positive correlation between those that were previously determined to be pathogenic, or likely to be pathogenic, and those that we found with compromised Complex I activity or subunit interactions in E. coli. In conclusion, this approach provides another way to explore the deleterious effects of human mitochondrial mutations, and it can contribute to molecular understanding of such mutations.
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Affiliation(s)
- Fang Zhang
- Department of Biological Sciences, Southern Methodist University, Dallas, TX 75275-0376, USA
| | - Quynh-Chi L Dang
- Department of Biological Sciences, Southern Methodist University, Dallas, TX 75275-0376, USA
| | - Steven B Vik
- Department of Biological Sciences, Southern Methodist University, Dallas, TX 75275-0376, USA.
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15
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Schon KR, Horvath R, Wei W, Calabrese C, Tucci A, Ibañez K, Ratnaike T, Pitceathly RDS, Bugiardini E, Quinlivan R, Hanna MG, Clement E, Ashton E, Sayer JA, Brennan P, Josifova D, Izatt L, Fratter C, Nesbitt V, Barrett T, McMullen DJ, Smith A, Deshpande C, Smithson SF, Festenstein R, Canham N, Caulfield M, Houlden H, Rahman S, Chinnery PF. Use of whole genome sequencing to determine genetic basis of suspected mitochondrial disorders: cohort study. BMJ 2021; 375:e066288. [PMID: 34732400 PMCID: PMC8565085 DOI: 10.1136/bmj-2021-066288] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 10/11/2021] [Indexed: 02/02/2023]
Abstract
OBJECTIVE To determine whether whole genome sequencing can be used to define the molecular basis of suspected mitochondrial disease. DESIGN Cohort study. SETTING National Health Service, England, including secondary and tertiary care. PARTICIPANTS 345 patients with suspected mitochondrial disorders recruited to the 100 000 Genomes Project in England between 2015 and 2018. INTERVENTION Short read whole genome sequencing was performed. Nuclear variants were prioritised on the basis of gene panels chosen according to phenotypes, ClinVar pathogenic/likely pathogenic variants, and the top 10 prioritised variants from Exomiser. Mitochondrial DNA variants were called using an in-house pipeline and compared with a list of pathogenic variants. Copy number variants and short tandem repeats for 13 neurological disorders were also analysed. American College of Medical Genetics guidelines were followed for classification of variants. MAIN OUTCOME MEASURE Definite or probable genetic diagnosis. RESULTS A definite or probable genetic diagnosis was identified in 98/319 (31%) families, with an additional 6 (2%) possible diagnoses. Fourteen of the diagnoses (4% of the 319 families) explained only part of the clinical features. A total of 95 different genes were implicated. Of 104 families given a diagnosis, 39 (38%) had a mitochondrial diagnosis and 65 (63%) had a non-mitochondrial diagnosis. CONCLUSION Whole genome sequencing is a useful diagnostic test in patients with suspected mitochondrial disorders, yielding a diagnosis in a further 31% after exclusion of common causes. Most diagnoses were non-mitochondrial disorders and included developmental disorders with intellectual disability, epileptic encephalopathies, other metabolic disorders, cardiomyopathies, and leukodystrophies. These would have been missed if a targeted approach was taken, and some have specific treatments.
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Affiliation(s)
- Katherine R Schon
- Department of Clinical Neurosciences, School of Clinical Medicine, University of Cambridge, Cambridge, UK
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge, UK
- East Anglian Medical Genetics Service, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK
| | - Rita Horvath
- Department of Clinical Neurosciences, School of Clinical Medicine, University of Cambridge, Cambridge, UK
| | - Wei Wei
- Department of Clinical Neurosciences, School of Clinical Medicine, University of Cambridge, Cambridge, UK
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge, UK
| | - Claudia Calabrese
- Department of Clinical Neurosciences, School of Clinical Medicine, University of Cambridge, Cambridge, UK
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge, UK
| | - Arianna Tucci
- William Harvey Research Institute, Queen Mary University of London, London, UK
| | - Kristina Ibañez
- William Harvey Research Institute, Queen Mary University of London, London, UK
| | - Thiloka Ratnaike
- Department of Clinical Neurosciences, School of Clinical Medicine, University of Cambridge, Cambridge, UK
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge, UK
- Department of Paediatrics, University of Cambridge, Cambridge, UK
| | - Robert D S Pitceathly
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology and The National Hospital for Neurology and Neurosurgery, London, UK
| | - Enrico Bugiardini
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology and The National Hospital for Neurology and Neurosurgery, London, UK
| | - Rosaline Quinlivan
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology and The National Hospital for Neurology and Neurosurgery, London, UK
| | - Michael G Hanna
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology and The National Hospital for Neurology and Neurosurgery, London, UK
| | - Emma Clement
- Department of Clinical Genetics and Genomic Medicine, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
| | - Emma Ashton
- NHS North Thames Genomic Laboratory Hub, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
| | - John A Sayer
- Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK
| | - Paul Brennan
- Northern Genetics Service, Newcastle Hospitals NHS Foundation Trust, International Centre for Life, Newcastle upon Tyne, UK
| | - Dragana Josifova
- Department of Clinical Genetics, Guy's and St Thomas' NHS Foundation Trust, London, UK
| | - Louise Izatt
- Department of Clinical Genetics, Guy's and St Thomas' NHS Foundation Trust, London, UK
| | - Carl Fratter
- NHS Highly Specialised Services for Rare Mitochondrial Disorders - Oxford Centre, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - Victoria Nesbitt
- NHS Highly Specialised Services for Rare Mitochondrial Disorders - Oxford Centre, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - Timothy Barrett
- Central and South Genome Medicine Service Alliance and Genomics Laboratory Hub, Birmingham Women's and Children's NHS Foundation Trust, Birmingham, UK
- Institute of Cancer and Genomic Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK
| | - Dominic J McMullen
- Central and South Genome Medicine Service Alliance and Genomics Laboratory Hub, Birmingham Women's and Children's NHS Foundation Trust, Birmingham, UK
| | - Audrey Smith
- Manchester Centre for Genomic Medicine, St Mary's Hospital, Manchester, UK
| | - Charulata Deshpande
- Department of Clinical Genetics, Guy's and St Thomas' NHS Foundation Trust, London, UK
- Manchester Centre for Genomic Medicine, St Mary's Hospital, Manchester, UK
| | - Sarah F Smithson
- Department of Brain Sciences, London Institute of Medical Sciences, Mansfield Centre for Inovation, Imperial College, Hammersmith Hospital, London, UK
| | | | - Natalie Canham
- Liverpool Centre for Genomic Medicine, Liverpool Women's Hospital, Liverpool, UK
| | - Mark Caulfield
- Genomics England, William Harvey Research Institute, Queen Mary University of London, London, UK
| | - Henry Houlden
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology and The National Hospital for Neurology and Neurosurgery, London, UK
- Neurology and Mitochondrial Disorders Genomics Clinical Interpretation Partnership, William Harvey Research Institute, Queen Mary University of London, London, UK
| | - Shamima Rahman
- Neurology and Mitochondrial Disorders Genomics Clinical Interpretation Partnership, William Harvey Research Institute, Queen Mary University of London, London, UK
- Metabolic Unit, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
- Mitochondrial Research Group, Department of Genetics and Genomic Medicine, UCL Great Ormond Street Institute of Child Health, London, UK
| | - Patrick F Chinnery
- Department of Clinical Neurosciences, School of Clinical Medicine, University of Cambridge, Cambridge, UK
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge, UK
- Neurology and Mitochondrial Disorders Genomics Clinical Interpretation Partnership, William Harvey Research Institute, Queen Mary University of London, London, UK
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16
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Cell reprogramming shapes the mitochondrial DNA landscape. Nat Commun 2021; 12:5241. [PMID: 34475388 PMCID: PMC8413449 DOI: 10.1038/s41467-021-25482-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Accepted: 08/14/2021] [Indexed: 12/25/2022] Open
Abstract
Individual induced pluripotent stem cells (iPSCs) show considerable phenotypic heterogeneity, but the reasons for this are not fully understood. Comprehensively analysing the mitochondrial genome (mtDNA) in 146 iPSC and fibroblast lines from 151 donors, we show that most age-related fibroblast mtDNA mutations are lost during reprogramming. However, iPSC-specific mutations are seen in 76.6% (108/141) of iPSC lines at a mutation rate of 8.62 × 10−5/base pair. The mutations observed in iPSC lines affect a higher proportion of mtDNA molecules, favouring non-synonymous protein-coding and tRNA variants, including known disease-causing mutations. Analysing 11,538 single cells shows stable heteroplasmy in sub-clones derived from the original donor during differentiation, with mtDNA variants influencing the expression of key genes involved in mitochondrial metabolism and epidermal cell differentiation. Thus, the dynamic mtDNA landscape contributes to the heterogeneity of human iPSCs and should be considered when using reprogrammed cells experimentally or as a therapy. Here the authors describe high depth mitochondrial DNA (mtDNA) sequence analysis of 146 human induced pluripotent stem cell (hiPSC) lines as well as single cell RNA-seq (scRNAseq) of hiPSCs undergoing differentiation from 125 donors; reporting mtDNA diversity and some variants favoured after reprogramming.
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