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Borbély N, Dudás D, Tapasztó A, Dudás-Boda E, Csáky V, Szeifert B, Mende BG, Egyed B, Szécsényi-Nagy A, Pamjav H. Phylogenetic insights into the genetic legacies of Hungarian-speaking communities in the Carpathian Basin. Sci Rep 2024; 14:11480. [PMID: 38769390 PMCID: PMC11106325 DOI: 10.1038/s41598-024-61978-4] [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: 01/31/2024] [Accepted: 05/13/2024] [Indexed: 05/22/2024] Open
Abstract
This study focuses on exploring the uniparental genetic lineages of Hungarian-speaking minorities residing in rural villages of Baranja (Croatia) and the Zobor region (Slovakia). We aimed to identify ancestral lineages by examining genetic markers distributed across the entire mitogenome and on the Y-chromosome. This allowed us to discern disparities in regional genetic structures within these communities. By integrating our newly acquired genetic data from a total of 168 participants with pre-existing Eurasian and ancient DNA datasets, our goal was to enrich the understanding of the genetic history trajectories of Carpathian Basin populations. Our findings suggest that while population-based analyses may not be sufficiently robust to detect fine-scale uniparental genetic patterns with the sample sizes at hand, phylogenetic analysis of well-characterized Y-chromosomal Short Tandem Repeat (STR) data and entire mitogenome sequences did uncover multiple lineage ties to far-flung regions and eras. While the predominant portions of both paternal and maternal DNA align with the East-Central European spectrum, rarer subhaplogroups and lineages have unveiled ancient ties to both prehistoric and historic populations spanning Europe and Eastern Eurasia. This research augments the expansive field of phylogenetics, offering critical perspectives on the genetic constitution and heritage of the communities in East-Central Europe.
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Affiliation(s)
- Noémi Borbély
- Institute of Archaeogenomics, HUN-REN Research Centre for the Humanities, Tóth Kálmán utca 4, Budapest, 1097, Hungary
- Doctoral School of Biology, Institute of Biology, ELTE Eötvös Loránd University, Pázmány Péter sétány 1/C, Budapest, 1117, Hungary
| | - Dániel Dudás
- Department of Reference Sample Analysis, Institute of Forensic Genetics, Hungarian Institute for Forensic Sciences, Gyorskocsi u. 25, Budapest, 1027, Hungary
| | - Attila Tapasztó
- Department of Reference Sample Analysis, Institute of Forensic Genetics, Hungarian Institute for Forensic Sciences, Gyorskocsi u. 25, Budapest, 1027, Hungary
| | - Eszter Dudás-Boda
- Department of Reference Sample Analysis, Institute of Forensic Genetics, Hungarian Institute for Forensic Sciences, Gyorskocsi u. 25, Budapest, 1027, Hungary
| | - Veronika Csáky
- Institute of Archaeogenomics, HUN-REN Research Centre for the Humanities, Tóth Kálmán utca 4, Budapest, 1097, Hungary
| | - Bea Szeifert
- Institute of Archaeogenomics, HUN-REN Research Centre for the Humanities, Tóth Kálmán utca 4, Budapest, 1097, Hungary
| | - Balázs Gusztáv Mende
- Institute of Archaeogenomics, HUN-REN Research Centre for the Humanities, Tóth Kálmán utca 4, Budapest, 1097, Hungary
| | - Balázs Egyed
- Department of Genetics, ELTE Eötvös Loránd University, Pázmány Péter sétány 1/C, Budapest, 1117, Hungary
| | - Anna Szécsényi-Nagy
- Institute of Archaeogenomics, HUN-REN Research Centre for the Humanities, Tóth Kálmán utca 4, Budapest, 1097, Hungary.
| | - Horolma Pamjav
- Department of Reference Sample Analysis, Institute of Forensic Genetics, Hungarian Institute for Forensic Sciences, Gyorskocsi u. 25, Budapest, 1027, Hungary.
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2
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Ferreira T, Rodriguez S. Mitochondrial DNA: Inherent Complexities Relevant to Genetic Analyses. Genes (Basel) 2024; 15:617. [PMID: 38790246 PMCID: PMC11121663 DOI: 10.3390/genes15050617] [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: 04/17/2024] [Revised: 05/09/2024] [Accepted: 05/10/2024] [Indexed: 05/26/2024] Open
Abstract
Mitochondrial DNA (mtDNA) exhibits distinct characteristics distinguishing it from the nuclear genome, necessitating specific analytical methods in genetic studies. This comprehensive review explores the complex role of mtDNA in a variety of genetic studies, including genome-wide, epigenome-wide, and phenome-wide association studies, with a focus on its implications for human traits and diseases. Here, we discuss the structure and gene-encoding properties of mtDNA, along with the influence of environmental factors and epigenetic modifications on its function and variability. Particularly significant are the challenges posed by mtDNA's high mutation rate, heteroplasmy, and copy number variations, and their impact on disease susceptibility and population genetic analyses. The review also highlights recent advances in methodological approaches that enhance our understanding of mtDNA associations, advocating for refined genetic research techniques that accommodate its complexities. By providing a comprehensive overview of the intricacies of mtDNA, this paper underscores the need for an integrated approach to genetic studies that considers the unique properties of mitochondrial genetics. Our findings aim to inform future research and encourage the development of innovative methodologies to better interpret the broad implications of mtDNA in human health and disease.
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Affiliation(s)
- Tomas Ferreira
- Bristol Medical School, University of Bristol, Bristol BS8 1UD, UK
- Department of Clinical Neurosciences, School of Clinical Medicine, University of Cambridge, Cambridge CB2 0SL, UK
| | - Santiago Rodriguez
- Bristol Medical School, University of Bristol, Bristol BS8 1UD, UK
- MRC Integrative Epidemiology Unit, Population Health Sciences, Bristol Medical School, University of Bristol, Bristol BS8 1QU, UK
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3
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Dobner J, Nguyen T, Dunkel A, Prigione A, Krutmann J, Rossi A. Mitochondrial DNA integrity and metabolome profile are preserved in the human induced pluripotent stem cell reference line KOLF2.1J. Stem Cell Reports 2024; 19:343-350. [PMID: 38402620 PMCID: PMC10937150 DOI: 10.1016/j.stemcr.2024.01.009] [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: 10/17/2023] [Revised: 01/25/2024] [Accepted: 01/26/2024] [Indexed: 02/27/2024] Open
Abstract
Quality control of human induced pluripotent stem cells (iPSCs) is critical to ensure reproducibility of research. Recently, KOLF2.1J was characterized and published as a male iPSC reference line to study neurological disorders. Emerging evidence suggests potential negative effects of mtDNA mutations, but its integrity was not analyzed in the original publication. To assess mtDNA integrity, we conducted a targeted mtDNA analysis followed by untargeted metabolomics analysis. We found that KOLF2.1J mtDNA integrity was intact at the time of publication and is still preserved in the commercially distributed cell line. In addition, the basal KOLF2.1J metabolome profile was similar to that of the two commercially available iPSC lines IMR90 and iPSC12, but clearly distinct from an in-house-generated ERCC6R683X/R683X iPSC line modeling Cockayne syndrome. Conclusively, we validate KOLF2.1J as a reference iPSC line, and encourage scientists to conduct mtDNA analysis and unbiased metabolomics whenever feasible.
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Affiliation(s)
- Jochen Dobner
- Institut für Umweltmedizinische Forschung (IUF)-Leibniz Research Institute for Environmental Medicine, Düsseldorf, Germany.
| | - Thach Nguyen
- Institut für Umweltmedizinische Forschung (IUF)-Leibniz Research Institute for Environmental Medicine, Düsseldorf, Germany
| | - Andreas Dunkel
- Leibniz Institute for Food Systems Biology at the Technical University of Munich, Freising, Germany
| | - Alessandro Prigione
- Department of General Pediatrics, Neonatology, and Pediatric Cardiology, Medical Faculty, Heinrich Heine University, Düsseldorf, Germany
| | - Jean Krutmann
- Institut für Umweltmedizinische Forschung (IUF)-Leibniz Research Institute for Environmental Medicine, Düsseldorf, Germany; Medical Faculty, Heinrich Heine University, Düsseldorf, Germany
| | - Andrea Rossi
- Institut für Umweltmedizinische Forschung (IUF)-Leibniz Research Institute for Environmental Medicine, Düsseldorf, Germany.
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4
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Uvizl M, Puechmaille SJ, Power S, Pippel M, Carthy S, Haerty W, Myers EW, Teeling EC, Huang Z. Comparative Genome Microsynteny Illuminates the Fast Evolution of Nuclear Mitochondrial Segments (NUMTs) in Mammals. Mol Biol Evol 2024; 41:msad278. [PMID: 38124445 PMCID: PMC10764098 DOI: 10.1093/molbev/msad278] [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: 07/18/2023] [Revised: 11/16/2023] [Accepted: 12/12/2023] [Indexed: 12/23/2023] Open
Abstract
The escape of DNA from mitochondria into the nuclear genome (nuclear mitochondrial DNA, NUMT) is an ongoing process. Although pervasively observed in eukaryotic genomes, their evolutionary trajectories in a mammal-wide context are poorly understood. The main challenge lies in the orthology assignment of NUMTs across species due to their fast evolution and chromosomal rearrangements over the past 200 million years. To address this issue, we systematically investigated the characteristics of NUMT insertions in 45 mammalian genomes and established a novel, synteny-based method to accurately predict orthologous NUMTs and ascertain their evolution across mammals. With a series of comparative analyses across taxa, we revealed that NUMTs may originate from nonrandom regions in mtDNA, are likely found in transposon-rich and intergenic regions, and unlikely code for functional proteins. Using our synteny-based approach, we leveraged 630 pairwise comparisons of genome-wide microsynteny and predicted the NUMT orthology relationships across 36 mammals. With the phylogenetic patterns of NUMT presence-and-absence across taxa, we constructed the ancestral state of NUMTs given the mammal tree using a coalescent method. We found support on the ancestral node of Fereuungulata within Laurasiatheria, whose subordinal relationships are still controversial. This study broadens our knowledge on NUMT insertion and evolution in mammalian genomes and highlights the merit of NUMTs as alternative genetic markers in phylogenetic inference.
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Affiliation(s)
- Marek Uvizl
- Department of Zoology, National Museum, 19300 Prague, Czech Republic
- Department of Zoology, Faculty of Science, Charles University, 12844 Prague, Czech Republic
| | - Sebastien J Puechmaille
- Institut des Sciences de l’Evolution de Montpellier (ISEM), University of Montpellier, 34095 Montpellier, France
- Institut Universitaire de France, Paris, France
| | - Sarahjane Power
- School of Biology and Environmental Science, University College Dublin, Belfield, Dublin 4, Ireland
| | - Martin Pippel
- Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany
- National Bioinformatics Infrastructure Sweden, Uppsala, Sweden
| | - Samuel Carthy
- School of Biology and Environmental Science, University College Dublin, Belfield, Dublin 4, Ireland
| | - Wilfried Haerty
- Earlham Institute, Norwich Research Park, Colney Ln, NR4 7UZ Norwich, UK
- School of Biological Sciences, University of East Anglia, Norwich, UK
| | - Eugene W Myers
- Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany
| | - Emma C Teeling
- School of Biology and Environmental Science, University College Dublin, Belfield, Dublin 4, Ireland
| | - Zixia Huang
- School of Biology and Environmental Science, University College Dublin, Belfield, Dublin 4, Ireland
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5
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Jiang L, Liu J, Li S, Wen Y, Zheng X, Qin L, Hou Y, Wang Z. CmVCall: An automated and adjustable nanopore analysis pipeline for heteroplasmy detection of the control region in human mitochondrial genome. Forensic Sci Int Genet 2023; 67:102930. [PMID: 37595417 DOI: 10.1016/j.fsigen.2023.102930] [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: 04/13/2023] [Revised: 08/09/2023] [Accepted: 08/10/2023] [Indexed: 08/20/2023]
Abstract
Genetic associations between human mitochondrial DNA (mtDNA) heteroplasmy and mitochondrial diseases, aging, and cancer have been elaborated, contributing a lot to the further understanding of mtDNA polymorphic spectrum in anthropology, population, and forensic genetics. In the past decade, heteroplasmy detection using Sanger sequencing and next generation sequencing (NGS) was hampered by the former's inefficiency and the latter's inherent bias due to amplification and mapping of short reads, respectively. Nanopore sequencing stands out for its ability to yield long contiguous segments of DNA, providing a new insight into heterogeneity authentication. In addition to MinION from Oxford Nanopore Technologies, an alternative nanopore sequencer QNome (Qitan Technology) has also been applied to various biological research and the forensic applicability of this platform has been proved recently. In this study, we evaluated the performance of four commonly used variant callers in the heterogeneity authentication of the control region of human mtDNA based on simulations of different ratios generated by mixing QNome nanopore sequencing reads of two synthetic sequences. Then, an open-source and python-based nanopore analytics pipeline, CmVCall was developed and incorporated multiple programs including reads filtering, removal of nuclear mitochondrial sequences (NUMTs), alignment, optional 'Correction' mode, and heterogeneity identification. CmVCall can achieve high precision, accuracy, and recall of 100%, 99.9%, and 92.3% with a 5% heteroplasmy level in 'Correction' mode. Moreover, blood, saliva, and hair shaft samples from monozygotic (MZ) twins were used for heterogeneity evaluation and comparison with the NGS data. Results of MZ twin samples showed that CmVCall could identify more point heteroplasmy sites, revealing significant levels of inter- and intra-individual mtDNA polymorphism. In conclusion, we believe that this analysis pipeline will lay a solid foundation for the development of a comprehensive nanopore analysis pipeline targeting the whole mitochondrial genome.
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Affiliation(s)
- Lirong Jiang
- Institute of Forensic Medicine, West China School of Basic Medical Sciences & Forensic Medicine, Sichuan University, Chengdu 610041, China
| | - Jing Liu
- Institute of Forensic Medicine, West China School of Basic Medical Sciences & Forensic Medicine, Sichuan University, Chengdu 610041, China
| | - Suyu Li
- Institute of Forensic Medicine, West China School of Basic Medical Sciences & Forensic Medicine, Sichuan University, Chengdu 610041, China
| | - Yufeng Wen
- School of Life Sciences, Jilin University, Changchun 130012, China
| | - Xinyue Zheng
- Institute of Forensic Medicine, West China School of Basic Medical Sciences & Forensic Medicine, Sichuan University, Chengdu 610041, China
| | - Liu Qin
- Qitan Technology Ltd., Chengdu, Chengdu 610044, China.
| | - Yiping Hou
- Institute of Forensic Medicine, West China School of Basic Medical Sciences & Forensic Medicine, Sichuan University, Chengdu 610041, China.
| | - Zheng Wang
- Institute of Forensic Medicine, West China School of Basic Medical Sciences & Forensic Medicine, Sichuan University, Chengdu 610041, China.
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6
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Vandiver AR, Hoang AN, Herbst A, Lee CC, Aiken JM, McKenzie D, Teitell MA, Timp W, Wanagat J. Nanopore sequencing identifies a higher frequency and expanded spectrum of mitochondrial DNA deletion mutations in human aging. Aging Cell 2023; 22:e13842. [PMID: 37132288 PMCID: PMC10265159 DOI: 10.1111/acel.13842] [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: 01/09/2023] [Revised: 03/23/2023] [Accepted: 03/27/2023] [Indexed: 05/04/2023] Open
Abstract
Mitochondrial DNA (mtDNA) deletion mutations cause many human diseases and are linked to age-induced mitochondrial dysfunction. Mapping the mutation spectrum and quantifying mtDNA deletion mutation frequency is challenging with next-generation sequencing methods. We hypothesized that long-read sequencing of human mtDNA across the lifespan would detect a broader spectrum of mtDNA rearrangements and provide a more accurate measurement of their frequency. We employed nanopore Cas9-targeted sequencing (nCATS) to map and quantitate mtDNA deletion mutations and develop analyses that are fit-for-purpose. We analyzed total DNA from vastus lateralis muscle in 15 males ranging from 20 to 81 years of age and substantia nigra from three 20-year-old and three 79-year-old men. We found that mtDNA deletion mutations detected by nCATS increased exponentially with age and mapped to a wider region of the mitochondrial genome than previously reported. Using simulated data, we observed that large deletions are often reported as chimeric alignments. To address this, we developed two algorithms for deletion identification which yield consistent deletion mapping and identify both previously reported and novel mtDNA deletion breakpoints. The identified mtDNA deletion frequency measured by nCATS correlates strongly with chronological age and predicts the deletion frequency as measured by digital PCR approaches. In substantia nigra, we observed a similar frequency of age-related mtDNA deletions to those observed in muscle samples, but noted a distinct spectrum of deletion breakpoints. NCATS-mtDNA sequencing allows the identification of mtDNA deletions on a single-molecule level, characterizing the strong relationship between mtDNA deletion frequency and chronological aging.
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Affiliation(s)
- Amy R. Vandiver
- Division of Dermatology, Department of MedicineUCLALos AngelesCaliforniaUSA
- Veterans Administration Greater Los Angeles Healthcare SystemLos AngelesCaliforniaUSA
| | - Austin N. Hoang
- Division of Geriatrics, Department of MedicineUCLALos AngelesCaliforniaUSA
| | - Allen Herbst
- US Geological Survey National Wildlife Health CenterMadisonWisconsinUSA
| | - Cathy C. Lee
- Veterans Administration Greater Los Angeles Healthcare SystemLos AngelesCaliforniaUSA
- Division of Geriatrics, Department of MedicineUCLALos AngelesCaliforniaUSA
| | - Judd M. Aiken
- Department of Agricultural, Food and Nutritional SciencesUniversity of AlbertaEdmontonAlbertaCanada
| | - Debbie McKenzie
- Department of Biological SciencesUniversity of AlbertaEdmontonAlbertaCanada
| | - Michael A. Teitell
- Molecular Biology InstituteUniversity of California at Los AngelesLos AngelesCaliforniaUSA
- Department of Pathology and Laboratory Medicine, David Geffen School of MedicineUniversity of California at Los AngelesLos AngelesCaliforniaUSA
- Department of Bioengineering, California NanoSystems Institute, Broad Center for Regenerative Medicine and Stem Cell ResearchUniversity of California at Los AngelesLos AngelesCaliforniaUSA
- Department of Pediatrics, David Geffen School of MedicineUniversity of California at Los AngelesLos AngelesCaliforniaUSA
- Jonsson Comprehensive Cancer Center, David Geffen School of MedicineUniversity of California at Los AngelesLos AngelesCaliforniaUSA
| | - Winston Timp
- Department of Molecular Biology and GeneticsJohns Hopkins University School of MedicineBaltimoreMarylandUSA
- Department of Biomedical EngineeringJohns Hopkins UniversityBaltimoreMarylandUSA
- Department of Genetic MedicineJohns Hopkins University School of MedicineBaltimoreMarylandUSA
| | - Jonathan Wanagat
- Veterans Administration Greater Los Angeles Healthcare SystemLos AngelesCaliforniaUSA
- Division of Geriatrics, Department of MedicineUCLALos AngelesCaliforniaUSA
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7
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Genetic testing for mitochondrial disease: the United Kingdom best practice guidelines. Eur J Hum Genet 2023; 31:148-163. [PMID: 36513735 PMCID: PMC9905091 DOI: 10.1038/s41431-022-01249-w] [Citation(s) in RCA: 20] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Revised: 11/12/2022] [Accepted: 11/16/2022] [Indexed: 12/15/2022] Open
Abstract
Primary mitochondrial disease describes a diverse group of neuro-metabolic disorders characterised by impaired oxidative phosphorylation. Diagnosis is challenging; >350 genes, both nuclear and mitochondrial DNA (mtDNA) encoded, are known to cause mitochondrial disease, leading to all possible inheritance patterns and further complicated by heteroplasmy of the multicopy mitochondrial genome. Technological advances, particularly next-generation sequencing, have driven a shift in diagnostic practice from 'biopsy first' to genome-wide analyses of blood and/or urine DNA. This has led to the need for a reference framework for laboratories involved in mitochondrial genetic testing to facilitate a consistent high-quality service. In the United Kingdom, consensus guidelines have been prepared by a working group of Clinical Scientists from the NHS Highly Specialised Service followed by national laboratory consultation. These guidelines summarise current recommended technologies and methodologies for the analysis of mtDNA and nuclear-encoded genes in patients with suspected mitochondrial disease. Genetic testing strategies for diagnosis, family testing and reproductive options including prenatal diagnosis are outlined. Importantly, recommendations for the minimum levels of mtDNA testing for the most common referral reasons are included, as well as guidance on appropriate referrals and information on the minimal appropriate gene content of panels when analysing nuclear mitochondrial genes. Finally, variant interpretation and recommendations for reporting of results are discussed, focussing particularly on the challenges of interpreting and reporting mtDNA variants.
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8
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Keraite I, Becker P, Canevazzi D, Frias-López C, Dabad M, Tonda-Hernandez R, Paramonov I, Ingham MJ, Brun-Heath I, Leno J, Abulí A, Garcia-Arumí E, Heath SC, Gut M, Gut IG. A method for multiplexed full-length single-molecule sequencing of the human mitochondrial genome. Nat Commun 2022; 13:5902. [PMID: 36202811 PMCID: PMC9537161 DOI: 10.1038/s41467-022-33530-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Accepted: 09/21/2022] [Indexed: 11/09/2022] Open
Abstract
Methods to reconstruct the mitochondrial DNA (mtDNA) sequence using short-read sequencing come with an inherent bias due to amplification and mapping. They can fail to determine the phase of variants, to capture multiple deletions and to cover the mitochondrial genome evenly. Here we describe a method to target, multiplex and sequence at high coverage full-length human mitochondrial genomes as native single-molecules, utilizing the RNA-guided DNA endonuclease Cas9. Combining Cas9 induced breaks, that define the mtDNA beginning and end of the sequencing reads, as barcodes, we achieve high demultiplexing specificity and delineation of the full-length of the mtDNA, regardless of the structural variant pattern. The long-read sequencing data is analysed with a pipeline where our custom-developed software, baldur, efficiently detects single nucleotide heteroplasmy to below 1%, physically determines phase and can accurately disentangle complex deletions. Our workflow is a tool for studying mtDNA variation and will accelerate mitochondrial research. Accurate analysis of mitochondrial DNA is important for mitochondrial disease clinical research and diagnostics. Here, authors present a method using Cas9 cleavage, nanopore sequencing and a custom pipeline to identify pathogenic variants, deletions and accurately quantify heteroplasmy to below 1%.
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Affiliation(s)
- Ieva Keraite
- CNAG-CRG, Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology (BIST), Barcelona, Spain
| | - Philipp Becker
- CNAG-CRG, Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology (BIST), Barcelona, Spain.,Qiagen, Hilden, Germany
| | - Davide Canevazzi
- CNAG-CRG, Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology (BIST), Barcelona, Spain
| | - Cristina Frias-López
- CNAG-CRG, Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology (BIST), Barcelona, Spain
| | - Marc Dabad
- CNAG-CRG, Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology (BIST), Barcelona, Spain
| | - Raúl Tonda-Hernandez
- CNAG-CRG, Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology (BIST), Barcelona, Spain
| | - Ida Paramonov
- CNAG-CRG, Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology (BIST), Barcelona, Spain
| | - Matthew John Ingham
- CNAG-CRG, Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology (BIST), Barcelona, Spain
| | - Isabelle Brun-Heath
- Institute for Research in Biomedicine (IRB Barcelona) - The Barcelona Institute of Science and Technology (BIST), Barcelona, Spain.,Joint IRB-BSC Program in Computational Biology, Barcelona, Spain
| | - Jordi Leno
- Department of Clinical and Molecular Genetics and Rare Disease, Hospital Universitari Vall d'Hebron, Barcelona, Spain.,Medicine Genetics Group, VHIR, Hospital Universitari Vall d'Hebron, Barcelona, Spain
| | - Anna Abulí
- Department of Clinical and Molecular Genetics and Rare Disease, Hospital Universitari Vall d'Hebron, Barcelona, Spain.,Medicine Genetics Group, VHIR, Hospital Universitari Vall d'Hebron, Barcelona, Spain
| | - Elena Garcia-Arumí
- Department of Clinical and Molecular Genetics and Rare Disease, Hospital Universitari Vall d'Hebron, Barcelona, Spain.,Research Group on Neuromuscular and Mitochondrial Disorders, VHIR, Hospital Universitari Vall d'Hebron, Barcelona, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Instituto de Salud Carlos III, Barcelona, Spain
| | - Simon Charles Heath
- CNAG-CRG, Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology (BIST), Barcelona, Spain.,Universitat Pompeu Fabra, Barcelona, Spain
| | - Marta Gut
- CNAG-CRG, Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology (BIST), Barcelona, Spain. .,Universitat Pompeu Fabra, Barcelona, Spain.
| | - Ivo Glynne Gut
- CNAG-CRG, Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology (BIST), Barcelona, Spain. .,Universitat Pompeu Fabra, Barcelona, Spain.
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9
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Long read mitochondrial genome sequencing using Cas9-guided adaptor ligation. Mitochondrion 2022; 65:176-183. [PMID: 35787470 DOI: 10.1016/j.mito.2022.06.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Revised: 05/11/2022] [Accepted: 06/19/2022] [Indexed: 11/21/2022]
Abstract
The mitochondrial genome (mtDNA) is an important source of disease-causing genetic variability, but existing sequencing methods limit understanding, precluding phased measurement of mutations and clear detection of large sporadic deletions. We adapted a method for amplification-free sequence enrichment using Cas9 cleavage to obtain full length nanopore reads of mtDNA. We then utilized the long reads to phase mutations in a patient with an mtDNA-linked syndrome and demonstrated that this method can map age-induced mtDNA deletions. We believe this method will offer deeper insight into our understanding of mtDNA variation.
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10
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Sturk-Andreaggi K, Ring JD, Ameur A, Gyllensten U, Bodner M, Parson W, Marshall C, Allen M. The Value of Whole-Genome Sequencing for Mitochondrial DNA Population Studies: Strategies and Criteria for Extracting High-Quality Mitogenome Haplotypes. Int J Mol Sci 2022; 23:ijms23042244. [PMID: 35216360 PMCID: PMC8876724 DOI: 10.3390/ijms23042244] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Revised: 02/08/2022] [Accepted: 02/09/2022] [Indexed: 02/04/2023] Open
Abstract
Whole-genome sequencing (WGS) data present a readily available resource for mitochondrial genome (mitogenome) haplotypes that can be utilized for genetics research including population studies. However, the reconstruction of the mitogenome is complicated by nuclear mitochondrial DNA (mtDNA) segments (NUMTs) that co-align with the mtDNA sequences and mimic authentic heteroplasmy. Two minimum variant detection thresholds, 5% and 10%, were assessed for the ability to produce authentic mitogenome haplotypes from a previously generated WGS dataset. Variants associated with NUMTs were detected in the mtDNA alignments for 91 of 917 (~8%) Swedish samples when the 5% frequency threshold was applied. The 413 observed NUMT variants were predominantly detected in two regions (nps 12,612–13,105 and 16,390–16,527), which were consistent with previously documented NUMTs. The number of NUMT variants was reduced by ~97% (400) using a 10% frequency threshold. Furthermore, the 5% frequency data were inconsistent with a platinum-quality mitogenome dataset with respect to observed heteroplasmy. These analyses illustrate that a 10% variant detection threshold may be necessary to ensure the generation of reliable mitogenome haplotypes from WGS data resources.
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Affiliation(s)
- Kimberly Sturk-Andreaggi
- Department of Immunology Genetics and Pathology, Uppsala University, Uppsala 751 08, Sweden; (A.A.); (U.G.)
- Armed Forces Medical Examiner System’s Armed Forces DNA Identification Laboratory (AFMES-AFDIL), Dover Air Force Base, Dover, DE 19902, USA; (J.D.R.); (C.M.)
- SNA International, LLC, Alexandria, VA 22314, USA
- Correspondence: (K.S.-A.); (M.A.)
| | - Joseph D. Ring
- Armed Forces Medical Examiner System’s Armed Forces DNA Identification Laboratory (AFMES-AFDIL), Dover Air Force Base, Dover, DE 19902, USA; (J.D.R.); (C.M.)
- SNA International, LLC, Alexandria, VA 22314, USA
| | - Adam Ameur
- Department of Immunology Genetics and Pathology, Uppsala University, Uppsala 751 08, Sweden; (A.A.); (U.G.)
| | - Ulf Gyllensten
- Department of Immunology Genetics and Pathology, Uppsala University, Uppsala 751 08, Sweden; (A.A.); (U.G.)
| | - Martin Bodner
- Institute of Legal Medicine, Medical University of Innsbruck, Innsbruck 6020, Austria; (M.B.); (W.P.)
| | - Walther Parson
- Institute of Legal Medicine, Medical University of Innsbruck, Innsbruck 6020, Austria; (M.B.); (W.P.)
- Forensic Science Program, The Pennsylvania State University, University Park, PA 16801, USA
| | - Charla Marshall
- Armed Forces Medical Examiner System’s Armed Forces DNA Identification Laboratory (AFMES-AFDIL), Dover Air Force Base, Dover, DE 19902, USA; (J.D.R.); (C.M.)
- SNA International, LLC, Alexandria, VA 22314, USA
- Forensic Science Program, The Pennsylvania State University, University Park, PA 16801, USA
| | - Marie Allen
- Department of Immunology Genetics and Pathology, Uppsala University, Uppsala 751 08, Sweden; (A.A.); (U.G.)
- Correspondence: (K.S.-A.); (M.A.)
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11
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Wang J, Balciuniene J, Diaz-Miranda MA, McCormick EM, Aref-Eshghi E, Muir AM, Cao K, Troiani J, Moseley A, Fan Z, Zolkipli-Cunningham Z, Goldstein A, Ganetzky RD, Muraresku CC, Peterson JT, Spinner NB, Wallace DC, Dulik MC, Falk MJ. Advanced approach for comprehensive mtDNA genome testing in mitochondrial disease. Mol Genet Metab 2022; 135:93-101. [PMID: 34969639 PMCID: PMC8877466 DOI: 10.1016/j.ymgme.2021.12.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/17/2021] [Revised: 12/13/2021] [Accepted: 12/14/2021] [Indexed: 01/16/2023]
Abstract
Mitochondrial disease diagnosis requires interrogation of both nuclear and mitochondrial (mtDNA) genomes for single-nucleotide variants (SNVs) and copy number alterations, both in the proband and often maternal relatives, together with careful phenotype correlation. We developed a comprehensive mtDNA sequencing test ('MitoGenome') using long-range PCR (LR-PCR) to amplify the full length of the mtDNA genome followed by next generation sequencing (NGS) to accurately detect SNVs and large-scale mtDNA deletions (LSMD), combined with droplet digital PCR (ddPCR) for LSMD heteroplasmy quantification. Overall, MitoGenome tests were performed on 428 samples from 394 patients with suspected or confirmed mitochondrial disease. The positive yield was 11% (43/394), including 34 patients with pathogenic or likely pathogenic SNVs (the most common being m.3243A > G in 8/34 (24%) patients), 8 patients with single LSMD, and 3 patients with multiple LSMD exceeding 10% heteroplasmy levels. Two patients with both LSMD and pathogenic SNV were detected. Overall, this LR-PCR/NGS assay provides a highly accurate and comprehensive diagnostic method for simultaneous mtDNA SNV detection at heteroplasmy levels as low as 1% and LSMD detection at heteroplasmy levels below 10%. Inclusion of maternal samples for variant classification and ddPCR to quantify LSMD heteroplasmy levels further enables accurate pathogenicity assessment and clinical correlation interpretation of mtDNA genome sequence variants and copy number alterations.
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Affiliation(s)
- Jing Wang
- Division of Genomic Diagnostics, Department of Pathology, The Children's Hospital of Philadelphia, Philadelphia, PA, USA; Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Jorune Balciuniene
- Division of Genomic Diagnostics, Department of Pathology, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Maria Alejandra Diaz-Miranda
- Division of Genomic Diagnostics, Department of Pathology, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Elizabeth M McCormick
- Mitochondrial Medicine Frontier Program, Division of Human Genetics, Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Erfan Aref-Eshghi
- Division of Genomic Diagnostics, Department of Pathology, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Alison M Muir
- Division of Genomic Diagnostics, Department of Pathology, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Kajia Cao
- Division of Genomic Diagnostics, Department of Pathology, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Juliana Troiani
- Division of Genomic Diagnostics, Department of Pathology, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Alicia Moseley
- Division of Genomic Diagnostics, Department of Pathology, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Zhiqian Fan
- Division of Genomic Diagnostics, Department of Pathology, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Zarazuela Zolkipli-Cunningham
- Mitochondrial Medicine Frontier Program, Division of Human Genetics, Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA, USA; Department of Pediatrics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Amy Goldstein
- Mitochondrial Medicine Frontier Program, Division of Human Genetics, Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA, USA; Department of Pediatrics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Rebecca D Ganetzky
- Mitochondrial Medicine Frontier Program, Division of Human Genetics, Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA, USA; Department of Pediatrics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Colleen C Muraresku
- Mitochondrial Medicine Frontier Program, Division of Human Genetics, Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - James T Peterson
- Mitochondrial Medicine Frontier Program, Division of Human Genetics, Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Nancy B Spinner
- Division of Genomic Diagnostics, Department of Pathology, The Children's Hospital of Philadelphia, Philadelphia, PA, USA; Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Douglas C Wallace
- Center for Mitochondrial and Epigenomic Medicine, Division of Human Genetics, Department of Pediatrics, The Children's Hospital of Philadelphia, USA; Department of Pediatrics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Matthew C Dulik
- Division of Genomic Diagnostics, Department of Pathology, The Children's Hospital of Philadelphia, Philadelphia, PA, USA; Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
| | - Marni J Falk
- Mitochondrial Medicine Frontier Program, Division of Human Genetics, Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA, USA; Department of Pediatrics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
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12
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Peretz RH, Ah Mew N, Vernon HJ, Ganetzky RD. Prospective diagnosis of MT-ATP6-related mitochondrial disease by newborn screening. Mol Genet Metab 2021; 134:37-42. [PMID: 34176718 PMCID: PMC8578202 DOI: 10.1016/j.ymgme.2021.06.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Revised: 06/18/2021] [Accepted: 06/19/2021] [Indexed: 11/24/2022]
Abstract
Elevated citrulline and C5-OH levels are reported as part of the newborn screening of core and secondary disorders on the Recommended Uniform Screening Panel (RUSP). Additionally, some state laboratory newborn screening programs report low citrulline levels, which may be observed in proximal urea cycle disorders. We report six patients who were found on newborn screening to have low citrulline and/or elevated C5-OH levels in whom confirmatory testing showed the combination of these two abnormal analytes. Mitochondrial sequencing revealed known pathogenic variants in MT-ATP6 at high heteroplasmy levels in all cases. MT-ATP6 at these heteroplasmy levels is associated with Leigh syndrome, a progressive neurodegenerative disease. Patients were treated with supplemental citrulline and, in some cases, mitochondrial cofactor therapy. These six patients have not experienced metabolic crises or developmental regression, and early diagnosis and management may help prevent the neurological sequelae of Leigh syndrome. The affected mothers and siblings are asymptomatic or paucisymptomatic (e.g. intellectual disability, depression, migraines, obsessive-compulsive disorder, and poor balance) despite high heteroplasmy or apparent homoplasmy of the familial variant, thus expanding the clinical spectrum seen in pathogenic variants of MT-ATP6. Confirmatory plasma amino acid analysis and acylcarnitine profiling should be ordered in a patient with either low citrulline and/or elevated C5-OH, as this combination appears specific for pathogenic variants in MT-ATP6.
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Affiliation(s)
- Ryan H Peretz
- National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, United States
| | - Nicholas Ah Mew
- Rare Disease Institute, Children's National Hospital, Washington, DC, United States
| | - Hilary J Vernon
- Department of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Rebecca D Ganetzky
- Mitochondrial Medicine Frontier Program, Division of Human Genetics, Children's Hospital of Philadelphia, Philadelphia, PA, United States; Department of Pediatrics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, United States.
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13
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mtDNA Heteroplasmy: Origin, Detection, Significance, and Evolutionary Consequences. Life (Basel) 2021; 11:life11070633. [PMID: 34209862 PMCID: PMC8307225 DOI: 10.3390/life11070633] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Accepted: 06/24/2021] [Indexed: 12/11/2022] Open
Abstract
Mitochondrial DNA (mtDNA) is predominately uniparentally transmitted. This results in organisms with a single type of mtDNA (homoplasmy), but two or more mtDNA haplotypes have been observed in low frequency in several species (heteroplasmy). In this review, we aim to highlight several aspects of heteroplasmy regarding its origin and its significance on mtDNA function and evolution, which has been progressively recognized in the last several years. Heteroplasmic organisms commonly occur through somatic mutations during an individual’s lifetime. They also occur due to leakage of paternal mtDNA, which rarely happens during fertilization. Alternatively, heteroplasmy can be potentially inherited maternally if an egg is already heteroplasmic. Recent advances in sequencing techniques have increased the ability to detect and quantify heteroplasmy and have revealed that mitochondrial DNA copies in the nucleus (NUMTs) can imitate true heteroplasmy. Heteroplasmy can have significant evolutionary consequences on the survival of mtDNA from the accumulation of deleterious mutations and for its coevolution with the nuclear genome. Particularly in humans, heteroplasmy plays an important role in the emergence of mitochondrial diseases and determines the success of the mitochondrial replacement therapy, a recent method that has been developed to cure mitochondrial diseases.
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14
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Weissensteiner H, Forer L, Fendt L, Kheirkhah A, Salas A, Kronenberg F, Schoenherr S. Contamination detection in sequencing studies using the mitochondrial phylogeny. Genome Res 2021; 31:309-316. [PMID: 33452015 PMCID: PMC7849411 DOI: 10.1101/gr.256545.119] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2019] [Accepted: 11/30/2020] [Indexed: 01/14/2023]
Abstract
Within-species contamination is a major issue in sequencing studies, especially for mitochondrial studies. Contamination can be detected by analyzing the nuclear genome or by inspecting polymorphic sites in the mitochondrial genome (mtDNA). Existing methods using the nuclear genome are computationally expensive, and no appropriate tool for detecting sample contamination in large-scale mtDNA data sets is available. Here we present haplocheck, a tool that requires only the mtDNA to detect contamination in both targeted mitochondrial and whole-genome sequencing studies. Our in silico simulations and amplicon mixture experiments indicate that haplocheck detects mtDNA contamination accurately and is independent of the phylogenetic distance within a sample mixture. By applying haplocheck to The 1000 Genomes Project Consortium data, we further evaluate the application of haplocheck as a fast proxy tool for nDNA-based contamination detection using the mtDNA and identify the mitochondrial copy number within a mixture as a critical component for the overall accuracy. The haplocheck tool is available both as a command-line tool and as a cloud web service producing interactive reports that facilitates the navigation through the phylogeny of contaminated samples.
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Affiliation(s)
- Hansi Weissensteiner
- Institute of Genetic Epidemiology, Department of Genetics and Pharmacology, Medical University of Innsbruck, 6020 Innsbruck, Austria
| | - Lukas Forer
- Institute of Genetic Epidemiology, Department of Genetics and Pharmacology, Medical University of Innsbruck, 6020 Innsbruck, Austria
| | - Liane Fendt
- Institute of Genetic Epidemiology, Department of Genetics and Pharmacology, Medical University of Innsbruck, 6020 Innsbruck, Austria
| | - Azin Kheirkhah
- Institute of Genetic Epidemiology, Department of Genetics and Pharmacology, Medical University of Innsbruck, 6020 Innsbruck, Austria
| | - Antonio Salas
- Unidade de Xenética, Instituto de Ciencias Forenses (INCIFOR), Facultade de Medicina, Universidade de Santiago de Compostela, and GenPoB Research Group, Instituto de Sanitarias (IDIS), Hospital Clínico Universitario de Santiago (SERGAS), 15782, Galicia, Spain
| | - Florian Kronenberg
- Institute of Genetic Epidemiology, Department of Genetics and Pharmacology, Medical University of Innsbruck, 6020 Innsbruck, Austria
| | - Sebastian Schoenherr
- Institute of Genetic Epidemiology, Department of Genetics and Pharmacology, Medical University of Innsbruck, 6020 Innsbruck, Austria
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15
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Guo X, Wang Y, Zhang R, Gu Z. STAMP: a multiplex sequencing method for simultaneous evaluation of mitochondrial DNA heteroplasmies and content. NAR Genom Bioinform 2020; 2:lqaa065. [PMID: 33134911 DOI: 10.1093/nargab/lqaa065] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2020] [Revised: 08/04/2020] [Accepted: 10/09/2020] [Indexed: 01/25/2023] Open
Abstract
Human mitochondrial genome (mtDNA) variations, such as mtDNA heteroplasmies (the co-existence of mutated and wild-type mtDNA), have received increasing attention in recent years for their clinical relevance to numerous diseases. But large-scale population studies of mtDNA heteroplasmies have been lagging due to the lack of a labor- and cost-effective method. Here, we present a novel human mtDNA sequencing method called STAMP (sequencing by targeted amplification of multiplex probes) for measuring mtDNA heteroplasmies and content in a streamlined workflow. We show that STAMP has high-mapping rates to mtDNA, deep coverage of unique reads and high tolerance to sequencing and polymerase chain reaction errors when applied to human samples. STAMP also has high sensitivity and low false positive rates in identifying artificial mtDNA variants at fractions as low as 0.5% in genomic DNA samples. We further extend STAMP, by including nuclear DNA-targeting probes, to enable assessment of relative mtDNA content in the same assay. The high cost-effectiveness of STAMP, along with the flexibility of using it for measuring various aspects of mtDNA variations, will accelerate the research of mtDNA heteroplasmies and content in large population cohorts, and in the context of human diseases and aging.
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Affiliation(s)
- Xiaoxian Guo
- Division of Nutritional Sciences, Cornell University, Ithaca, NY 14853, USA
| | - Yiqin Wang
- Division of Nutritional Sciences, Cornell University, Ithaca, NY 14853, USA
| | - Ruoyu Zhang
- Division of Nutritional Sciences, Cornell University, Ithaca, NY 14853, USA
| | - Zhenglong Gu
- Division of Nutritional Sciences, Cornell University, Ithaca, NY 14853, USA
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16
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Stewart JB, Chinnery PF. Extreme heterogeneity of human mitochondrial DNA from organelles to populations. Nat Rev Genet 2020; 22:106-118. [PMID: 32989265 DOI: 10.1038/s41576-020-00284-x] [Citation(s) in RCA: 108] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/25/2020] [Indexed: 02/06/2023]
Abstract
Contrary to the long-held view that most humans harbour only identical mitochondrial genomes, deep resequencing has uncovered unanticipated extreme genetic variation within mitochondrial DNA (mtDNA). Most, if not all, humans contain multiple mtDNA genotypes (heteroplasmy); specific patterns of variants accumulate in different tissues, including cancers, over time; and some variants are preferentially passed down or suppressed in the maternal germ line. These findings cast light on the origin and spread of mtDNA mutations at multiple scales, from the organelle to the human population, and challenge the conventional view that high percentages of a mutation are required before a new variant has functional consequences.
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Affiliation(s)
- James B Stewart
- Max Planck Institute for Biology of Ageing, Cologne, Germany.,Wellcome Centre for Mitochondrial Research, Newcastle University Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK
| | - Patrick F Chinnery
- Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK. .,Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge, UK.
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17
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Distinguishing mitochondrial DNA and NUMT sequences amplified with the precision ID mtDNA whole genome panel. Mitochondrion 2020; 55:122-133. [PMID: 32949792 DOI: 10.1016/j.mito.2020.09.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Revised: 08/31/2020] [Accepted: 09/04/2020] [Indexed: 11/22/2022]
Abstract
Nuclear mitochondrial DNA segments (NUMTs) are generated via transfer of portions of the mitochondrial genome into the nuclear genome. Given their common origin, there is the possibility that both the mitochondrial and NUMT segments may co-amplify using the same set of primers. Thus, analysis of the variation of the mitochondrial genome must take into account this co-amplification of mitochondrial and NUMT sequences. The study herein builds on data from the study by Strobl et al. (Strobl et al., 2019), in which multiple point heteroplasmies were called with an "N" to prevent labeling NUMT sequences mimicking mitochondrial heteroplasmy and being interpreted as true mitochondrial in origin sequence variants. Each of these point heteroplasmies was studied in greater detail, both molecularly and bioinformatically, to determine whether NUMT or true mitochondrial DNA variation was present. The bioinformatic and molecular tools available to help distinguish between NUMT and mitochondrial DNA and the effect of NUMT sequences on interpretation were discussed.
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18
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Schon KR, Ratnaike T, van den Ameele J, Horvath R, Chinnery PF. Mitochondrial Diseases: A Diagnostic Revolution. Trends Genet 2020; 36:702-717. [PMID: 32674947 DOI: 10.1016/j.tig.2020.06.009] [Citation(s) in RCA: 57] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Revised: 06/18/2020] [Accepted: 06/19/2020] [Indexed: 12/26/2022]
Abstract
Mitochondrial disorders have emerged as a common cause of inherited disease, but are traditionally viewed as being difficult to diagnose clinically, and even more difficult to comprehensively characterize at the molecular level. However, new sequencing approaches, particularly whole-genome sequencing (WGS), have dramatically changed the landscape. The combined analysis of nuclear and mitochondrial DNA (mtDNA) allows rapid diagnosis for the vast majority of patients, but new challenges have emerged. We review recent discoveries that will benefit patients and families, and highlight emerging questions that remain to be resolved.
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Affiliation(s)
- Katherine R Schon
- Department of Clinical Neurosciences, School of Clinical Medicine, University of Cambridge, Cambridge Biomedical Campus, Cambridge, UK; Medical Research Council (MRC) Mitochondrial Biology Unit, University of Cambridge, Cambridge Biomedical Campus, Cambridge, UK
| | - Thiloka Ratnaike
- Department of Clinical Neurosciences, School of Clinical Medicine, University of Cambridge, Cambridge Biomedical Campus, Cambridge, UK; Medical Research Council (MRC) Mitochondrial Biology Unit, University of Cambridge, Cambridge Biomedical Campus, Cambridge, UK; Department of Paediatrics, School of Clinical Medicine, University of Cambridge, Cambridge Biomedical Campus, Cambridge, UK
| | - Jelle van den Ameele
- Department of Clinical Neurosciences, School of Clinical Medicine, University of Cambridge, Cambridge Biomedical Campus, Cambridge, UK; Medical Research Council (MRC) Mitochondrial Biology Unit, University of Cambridge, Cambridge Biomedical Campus, Cambridge, UK
| | - Rita Horvath
- Department of Clinical Neurosciences, School of Clinical Medicine, University of Cambridge, Cambridge Biomedical Campus, Cambridge, UK
| | - Patrick F Chinnery
- Department of Clinical Neurosciences, School of Clinical Medicine, University of Cambridge, Cambridge Biomedical Campus, Cambridge, UK; Medical Research Council (MRC) Mitochondrial Biology Unit, University of Cambridge, Cambridge Biomedical Campus, Cambridge, UK.
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19
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Maeda R, Kami D, Maeda H, Shikuma A, Gojo S. High throughput single cell analysis of mitochondrial heteroplasmy in mitochondrial diseases. Sci Rep 2020; 10:10821. [PMID: 32616755 PMCID: PMC7331593 DOI: 10.1038/s41598-020-67686-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2019] [Accepted: 06/11/2020] [Indexed: 12/21/2022] Open
Abstract
Mitochondrial heteroplasmy, which fundamentally means intracellular heterogeneity of mitochondrial DNA (mtDNA), has been measured in a group of cells, regardless of intercellular heterogeneity. Ordinal methods for mitochondrial heteroplasmy cannot discriminate between an intercellular homogenic population composed of cells with similar intracellular heterogeneity for mtDNA and an intercellular heterogenic population composed of cells with different rates of mutated mtDNA. A high-throughput method to determine mitochondrial heteroplasmy in a single cell was developed by using droplet digital PCR with TaqMan polymerase in this study. This technique revealed that there are three different cell populations of cultured fibroblasts derived from patients with mitochondrial disease carrying a mutation in the mtDNA; cells with homoplasmy of either mutated or healthy mtDNA; and cells mixed with mutated and healthy mtDNA. The presence of intercellular heterogeneity, even in uniformed cultured fibroblasts, suggests that heterogeneity should exist among different kinds of cells. The diagnosis of intercellular heterogeneity with respect to mitochondrial heteroplasmy by this methodology could provide novel insight into developing a treatment strategy for mitochondrial diseases.
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Affiliation(s)
- Ryotaro Maeda
- Department of Cardiovascular Medicine, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, 465, Kajii cho, Kamigyo ku, Kyoto, 802-8566, Japan
| | - Daisuke Kami
- Department of Regenerative Medicine, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, 465, Kajii cho, Kamigyo ku, Kyoto, 802-8566, Japan
| | - Hideki Maeda
- Department of Cardiovascular Medicine, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, 465, Kajii cho, Kamigyo ku, Kyoto, 802-8566, Japan
| | - Akira Shikuma
- Department of Cardiovascular Medicine, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, 465, Kajii cho, Kamigyo ku, Kyoto, 802-8566, Japan
| | - Satoshi Gojo
- Department of Regenerative Medicine, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, 465, Kajii cho, Kamigyo ku, Kyoto, 802-8566, Japan.
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20
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Ricardo PC, Françoso E, Arias MC. Mitochondrial DNA intra-individual variation in a bumblebee species: A challenge for evolutionary studies and molecular identification. Mitochondrion 2020; 53:243-254. [PMID: 32569843 DOI: 10.1016/j.mito.2020.06.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2020] [Revised: 04/28/2020] [Accepted: 06/15/2020] [Indexed: 10/24/2022]
Abstract
Mitochondrial DNA (mtDNA) regions have been widely used as molecular markers in evolutionary studies and species identification. However, the presence of heteroplasmy and NUMTs may represent obstacles. Heteroplasmy is a state where an organism has different mitochondrial haplotypes. NUMTs are nuclear pseudogenes originating from mtDNA sequences transferred to nuclear DNA. Evidences of heteroplasmy were already verified in the bumblebee Bombus morio in an earlier study. The present work investigated in more detail the presence of intra-individual haplotypes variation in this species. Heteroplasmy was detected in individuals from all the ten sampled locations, with an average of six heteroplasmic haplotypes per individual. In addition, some of these heteroplasmic haplotypes were shared among individuals from different locations, suggesting the existence of stable heteroplasmy in B. morio. These results demonstrated that heteroplasmy is likely to affect inferences based on mtDNA analysis, especially in phylogenetic, phylogeographic and population genetics studies. In addition, NUMTs were also detected. These sequences showed divergence of 2.7% to 12% in relation to the mitochondrial haplotypes. These levels of divergence could mislead conclusions in evolutionary studies and affect species identification through DNA barcoding.
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Affiliation(s)
- Paulo Cseri Ricardo
- Departamento de Genética e Biologia Evolutiva, Instituto de Biociências, Universidade de São Paulo, São Paulo, SP, Brazil.
| | - Elaine Françoso
- Departamento de Genética e Biologia Evolutiva, Instituto de Biociências, Universidade de São Paulo, São Paulo, SP, Brazil
| | - Maria Cristina Arias
- Departamento de Genética e Biologia Evolutiva, Instituto de Biociências, Universidade de São Paulo, São Paulo, SP, Brazil.
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21
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Patterson EI, Khanipov K, Swetnam DM, Walsdorf S, Kautz TF, Thangamani S, Fofanov Y, Forrester NL. Measuring Alphavirus Fidelity Using Non-Infectious Virus Particles. Viruses 2020; 12:v12050546. [PMID: 32429270 PMCID: PMC7291308 DOI: 10.3390/v12050546] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Revised: 05/06/2020] [Accepted: 05/13/2020] [Indexed: 01/17/2023] Open
Abstract
Mutations are incorporated into the genomes of RNA viruses at an optimal frequency and altering this precise frequency has been proposed as a strategy to create live-attenuated vaccines. However, determining the effect of specific mutations that alter fidelity has been difficult because of the rapid selection of the virus population during replication. By deleting residues of the structural polyprotein PE2 cleavage site, E3Δ56-59, in Venezuelan equine encephalitis virus (VEEV) TC-83 vaccine strain, non-infectious virus particles were used to assess the effect of single mutations on mutation frequency without the interference of selection that results from multiple replication cycles. Next-generation sequencing analysis revealed a significantly lower frequency of transversion mutations and overall mutation frequency for the fidelity mutants compared to VEEV TC-83 E3Δ56-59. We demonstrate that deletion of the PE2 cleavage site halts virus infection while making the virus particles available for downstream sequencing. The conservation of the site will allow the evaluation of suspected fidelity mutants across alphaviruses of medical importance.
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Affiliation(s)
- Edward I. Patterson
- Department of Pathology, University of Texas Medical Branch, Galveston, TX 77555, USA; (S.W.); (S.T.); (N.L.F.)
- Centre for Neglected Tropical Diseases, Departments of Vector Biology and Tropical Disease Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK
- Correspondence:
| | - Kamil Khanipov
- Department of Pharmacology and Toxicology, Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, TX 77555, USA; (K.K.); (Y.F.)
| | - Daniele M. Swetnam
- Department of Pathology, Microbiology, and Immunology, School of Veterinary Medicine, University of California, Davis, Davis, CA 95616, USA;
| | - Samantha Walsdorf
- Department of Pathology, University of Texas Medical Branch, Galveston, TX 77555, USA; (S.W.); (S.T.); (N.L.F.)
| | - Tiffany F. Kautz
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX 77555, USA;
| | - Saravanan Thangamani
- Department of Pathology, University of Texas Medical Branch, Galveston, TX 77555, USA; (S.W.); (S.T.); (N.L.F.)
| | - Yuriy Fofanov
- Department of Pharmacology and Toxicology, Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, TX 77555, USA; (K.K.); (Y.F.)
| | - Naomi L. Forrester
- Department of Pathology, University of Texas Medical Branch, Galveston, TX 77555, USA; (S.W.); (S.T.); (N.L.F.)
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22
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Sensitivity of mitochondrial DNA heteroplasmy detection using Next Generation Sequencing. Mitochondrion 2020; 50:88-93. [DOI: 10.1016/j.mito.2019.10.006] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Accepted: 10/10/2019] [Indexed: 01/03/2023]
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23
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Maude H, Davidson M, Charitakis N, Diaz L, Bowers WHT, Gradovich E, Andrew T, Huntley D. NUMT Confounding Biases Mitochondrial Heteroplasmy Calls in Favor of the Reference Allele. Front Cell Dev Biol 2019; 7:201. [PMID: 31612134 PMCID: PMC6773831 DOI: 10.3389/fcell.2019.00201] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2019] [Accepted: 09/05/2019] [Indexed: 12/30/2022] Open
Abstract
Homology between mitochondrial DNA (mtDNA) and nuclear DNA of mitochondrial origin (nuMTs) causes confounding when aligning short sequence reads to the reference human genome, as the true sequence origin cannot be determined. Using a systematic in silico approach, we here report the impact of all potential mitochondrial variants on alignment accuracy and variant calling. A total of 49,707 possible mutations were introduced across the 16,569 bp reference mitochondrial genome (16,569 × 3 alternative alleles), one variant at-at-time. The resulting in silico fragmentation and alignment to the entire reference genome (GRCh38) revealed preferential mapping of mutated mitochondrial fragments to nuclear loci, as variants increased loci similarity to nuMTs, for a total of 807, 362, and 41 variants at 333, 144, and 27 positions when using 100, 150, and 300 bp single-end fragments. We subsequently modeled these affected variants at 50% heteroplasmy and carried out variant calling, observing bias in the reported allele frequencies in favor of the reference allele. Four variants (chrM:6023A, chrM:4456T, chrM:5147A, and chrM:7521A) including a possible hypertension factor, chrM:4456T, caused 100% loss of coverage at the mutated position (with all 100 bp single-end fragments aligning to homologous, nuclear positions instead of chrM), rendering these variants undetectable when aligning to the entire reference genome. Furthermore, four mitochondrial variants reported to be pathogenic were found to cause significant loss of coverage and select haplogroup-defining SNPs were shown to exacerbate the loss of coverage caused by surrounding variants. Increased fragment length and use of paired-end reads both improved alignment accuracy.
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Affiliation(s)
- Hannah Maude
- Department of Life Sciences, Imperial College London, London, United Kingdom
- Section of Genomics of Common Disease, Imperial College London, London, United Kingdom
| | - Mira Davidson
- Department of Life Sciences, Imperial College London, London, United Kingdom
| | - Natalie Charitakis
- Department of Life Sciences, Imperial College London, London, United Kingdom
| | - Leo Diaz
- Department of Life Sciences, Imperial College London, London, United Kingdom
| | | | - Eva Gradovich
- Department of Life Sciences, Imperial College London, London, United Kingdom
| | - Toby Andrew
- Section of Genomics of Common Disease, Imperial College London, London, United Kingdom
| | - Derek Huntley
- Department of Life Sciences, Imperial College London, London, United Kingdom
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24
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Duan M, Chen L, Ge Q, Lu N, Li J, Pan X, Qiao Y, Tu J, Lu Z. Evaluating heteroplasmic variations of the mitochondrial genome from whole genome sequencing data. Gene 2019; 699:145-154. [PMID: 30876822 DOI: 10.1016/j.gene.2019.03.016] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2018] [Revised: 03/08/2019] [Accepted: 03/11/2019] [Indexed: 12/23/2022]
Abstract
BACKGROUND Detecting heteroplasmic variations in the mitochondrial genome can help identify potential pathogenic possibilities, which is significant for disease prevention. The development of next-generation sequencing changed the quantification of mitochondrial DNA (mtDNA) heteroplasmy from scanning limited recorded points to the entire mitochondrial genome. However, due to the presence of nuclear mtDNA homologous sequences (nuMTs), maximally retaining real variations while excluding falsest heteroplasmic variations from nuMTs and sequencing errors presents a dilemma. RESULTS Herein, we used an improved method for detecting low-frequency mtDNA heteroplasmic variations from whole genome sequencing data, including point variations and short-fragment length alterations, and evaluated the effect of this method. A two-step alignment was designed and performed to accelerate data processing, to obtain and retain the true mtDNA reads and to eliminate most nuMTs reads. After analyzing whole genome sequencing data of K562 and GM12878 cells, ~90% of heteroplasmic point variations were identified in MitoMap. The results were consistent with the results of an amplification refractory mutation system qPCR. Many linkages of the detected heteroplasmy variations were also discovered. CONCLUSIONS Our improved method is a simple, efficient and accurate way to mine mitochondrial low-frequency heteroplasmic variations from whole genome sequencing data. By evaluating the highest misalignment possibility caused by the remaining nuMTs-like reads and sequencing errors, our procedure can detect mtDNA heteroplasmic variations whose heteroplasmy frequencies are as low as 0.2%.
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Affiliation(s)
- Mengqin Duan
- State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096, China
| | - Liang Chen
- State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096, China
| | - Qinyu Ge
- State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096, China
| | - Na Lu
- State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096, China
| | - Junji Li
- State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096, China
| | - Xuan Pan
- Jiangsu Cancer Hospital, Jiangsu Institute of Cancer Research, Nanjing Medical University Affiliated Cancer Hospital, Nanjing 210009, China
| | - Yi Qiao
- State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096, China
| | - Jing Tu
- State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096, China.
| | - Zuhong Lu
- State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096, China.
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25
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Weerts MJA, Smid M, Foekens JA, Sleijfer S, Martens JWM. Mitochondrial RNA Expression and Single Nucleotide Variants in Association with Clinical Parameters in Primary Breast Cancers. Cancers (Basel) 2018; 10:cancers10120500. [PMID: 30544876 PMCID: PMC6318759 DOI: 10.3390/cancers10120500] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2018] [Revised: 12/06/2018] [Accepted: 12/07/2018] [Indexed: 12/21/2022] Open
Abstract
The human mitochondrial DNA (mtDNA) encodes 37 genes, including thirteen proteins essential for the respiratory chain, and RNAs functioning in the mitochondrial translation apparatus. The total number of mtDNA molecules per cell (mtDNA content) is variable between tissue types and also between tumors and their normal counterparts. For breast cancer, tumors tend to be depleted in their mtDNA content compared to adjacent normal mammary tissue. Various studies have shown that primary breast tumors harbor somatic mtDNA variants. A decrease in mtDNA content or the presence of somatic variants could indicate a reduced mitochondrial function within breast cancer. In this explorative study we aimed to further understand genomic changes and expression of the mitochondrial genome within breast cancer, by analyzing RNA sequencing data of primary breast tumor specimens of 344 cases. We demonstrate that somatic variants detected at the mtRNA level are representative for somatic variants in the mtDNA. Also, the number of somatic variants within the mitochondrial transcriptome is not associated with mutational processes impacting the nuclear genome, but is positively associated with age at diagnosis. Finally, we observe that mitochondrial expression is related to ER status. We conclude that there is a large heterogeneity in somatic mutations of the mitochondrial genome within primary breast tumors, and differences in mitochondrial expression among breast cancer subtypes. The exact impact on metabolic differences and clinical relevance deserves further study.
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Affiliation(s)
- Marjolein J A Weerts
- Department of Medical Oncology and Cancer Genomics Netherlands, Erasmus MC Cancer Institute, Erasmus University Medical Center, 3015 CE Rotterdam, The Netherlands.
| | - Marcel Smid
- Department of Medical Oncology and Cancer Genomics Netherlands, Erasmus MC Cancer Institute, Erasmus University Medical Center, 3015 CE Rotterdam, The Netherlands.
| | - John A Foekens
- Department of Medical Oncology and Cancer Genomics Netherlands, Erasmus MC Cancer Institute, Erasmus University Medical Center, 3015 CE Rotterdam, The Netherlands.
| | - Stefan Sleijfer
- Department of Medical Oncology and Cancer Genomics Netherlands, Erasmus MC Cancer Institute, Erasmus University Medical Center, 3015 CE Rotterdam, The Netherlands.
| | - John W M Martens
- Department of Medical Oncology and Cancer Genomics Netherlands, Erasmus MC Cancer Institute, Erasmus University Medical Center, 3015 CE Rotterdam, The Netherlands.
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26
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Weerts MJA, Timmermans EC, Vossen RHAM, van Strijp D, Van den Hout-van Vroonhoven MCGN, van IJcken WFJ, van der Zaag PJ, Anvar SY, Sleijfer S, Martens JWM. Sensitive detection of mitochondrial DNA variants for analysis of mitochondrial DNA-enriched extracts from frozen tumor tissue. Sci Rep 2018; 8:2261. [PMID: 29396409 PMCID: PMC5797170 DOI: 10.1038/s41598-018-20623-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Accepted: 01/22/2018] [Indexed: 11/25/2022] Open
Abstract
Large variation exists in mitochondrial DNA (mtDNA) not only between but also within individuals. Also in human cancer, tumor-specific mtDNA variation exists. In this work, we describe the comparison of four methods to extract mtDNA as pure as possible from frozen tumor tissue. Also, three state-of-the-art methods for sensitive detection of mtDNA variants were evaluated. The main aim was to develop a procedure to detect low-frequent single-nucleotide mtDNA-specific variants in frozen tumor tissue. We show that of the methods evaluated, DNA extracted from cytosol fractions following exonuclease treatment results in highest mtDNA yield and purity from frozen tumor tissue (270-fold mtDNA enrichment). Next, we demonstrate the sensitivity of detection of low-frequent single-nucleotide mtDNA variants (≤1% allele frequency) in breast cancer cell lines MDA-MB-231 and MCF-7 by single-molecule real-time (SMRT) sequencing, UltraSEEK chemistry based mass spectrometry, and digital PCR. We also show de novo detection and allelic phasing of variants by SMRT sequencing. We conclude that our sensitive procedure to detect low-frequent single-nucleotide mtDNA variants from frozen tumor tissue is based on extraction of DNA from cytosol fractions followed by exonuclease treatment to obtain high mtDNA purity, and subsequent SMRT sequencing for (de novo) detection and allelic phasing of variants.
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Affiliation(s)
- M J A Weerts
- Department of Medical Oncology and Cancer Genomics Netherlands, Erasmus MC Cancer Institute, Rotterdam, The Netherlands.
| | - E C Timmermans
- Philips Research Laboratories, High Tech Campus 11, 5656 AE, Eindhoven, The Netherlands
| | - R H A M Vossen
- Leiden Genome Technology Center (LGTC), Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - D van Strijp
- Philips Research Laboratories, High Tech Campus 11, 5656 AE, Eindhoven, The Netherlands
| | | | | | - P J van der Zaag
- Philips Research Laboratories, High Tech Campus 11, 5656 AE, Eindhoven, The Netherlands
| | - S Y Anvar
- Leiden Genome Technology Center (LGTC), Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands.,Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands.,Department of Clinical Pharmacy and Toxicology, Leiden University Medical Center, Leiden, The Netherlands
| | - S Sleijfer
- Department of Medical Oncology and Cancer Genomics Netherlands, Erasmus MC Cancer Institute, Rotterdam, The Netherlands
| | - J W M Martens
- Department of Medical Oncology and Cancer Genomics Netherlands, Erasmus MC Cancer Institute, Rotterdam, The Netherlands
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