1
|
Willis JCW, Silva-Pinheiro P, Widdup L, Minczuk M, Liu DR. Compact zinc finger base editors that edit mitochondrial or nuclear DNA in vitro and in vivo. Nat Commun 2022; 13:7204. [PMID: 36418298 PMCID: PMC9684478 DOI: 10.1038/s41467-022-34784-7] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Accepted: 11/07/2022] [Indexed: 11/25/2022] Open
Abstract
DddA-derived cytosine base editors (DdCBEs) use programmable DNA-binding TALE repeat arrays, rather than CRISPR proteins, a split double-stranded DNA cytidine deaminase (DddA), and a uracil glycosylase inhibitor to mediate C•G-to-T•A editing in nuclear and organelle DNA. Here we report the development of zinc finger DdCBEs (ZF-DdCBEs) and the improvement of their editing performance through engineering their architectures, defining improved ZF scaffolds, and installing DddA activity-enhancing mutations. We engineer variants with improved DNA specificity by integrating four strategies to reduce off-target editing. We use optimized ZF-DdCBEs to install or correct disease-associated mutations in mitochondria and in the nucleus. Leveraging their small size, we use a single AAV9 to deliver into heart, liver, and skeletal muscle in post-natal mice ZF-DdCBEs that efficiently install disease-associated mutations. While off-target editing of ZF-DdCBEs is likely too high for therapeutic applications, these findings demonstrate a compact, all-protein base editing research tool for precise editing of organelle or nuclear DNA without double-strand DNA breaks.
Collapse
Affiliation(s)
- Julian C W Willis
- Merkin Institute of Transformative Technologies in Healthcare, Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA
- Howard Hughes Medical Institute, Harvard University, Cambridge, MA, USA
| | | | - Lily Widdup
- Merkin Institute of Transformative Technologies in Healthcare, Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA
- Howard Hughes Medical Institute, Harvard University, Cambridge, MA, USA
| | - Michal Minczuk
- MRC Mitochondrial Biology Unit, University of Cambridge, Cambridge, UK
| | - David R Liu
- Merkin Institute of Transformative Technologies in Healthcare, Broad Institute of MIT and Harvard, Cambridge, MA, USA.
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA.
- Howard Hughes Medical Institute, Harvard University, Cambridge, MA, USA.
| |
Collapse
|
2
|
Toncheva D, Serbezov D, Karachanak-Yankova S, Nesheva D. Ancient mitochondrial DNA pathogenic variants putatively associated with mitochondrial disease. PLoS One 2020; 15:e0233666. [PMID: 32970680 PMCID: PMC7514063 DOI: 10.1371/journal.pone.0233666] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2020] [Accepted: 08/09/2020] [Indexed: 11/18/2022] Open
Abstract
Mitochondrial DNA variants associated with diseases are widely studied in contemporary populations, but their prevalence has not yet been investigated in ancient populations. The publicly available AmtDB database contains 1443 ancient mtDNA Eurasian genomes from different periods. The objective of this study was to use this data to establish the presence of pathogenic mtDNA variants putatively associated with mitochondrial diseases in ancient populations. The clinical significance, pathogenicity prediction and contemporary frequency of mtDNA variants were determined using online platforms. The analyzed ancient mtDNAs contain six variants designated as being "confirmed pathogenic" in modern patients. The oldest of these, m.7510T>C in the MT-TS1 gene, was found in a sample from the Neolithic period, dated 5800-5400 BCE. All six have well established clinical association, and their pathogenic effect is corroborated by very low population frequencies in contemporary populations. Analysis of the geographic location of the ancient samples, contemporary epidemiological trends and probable haplogroup association indicate diverse spatiotemporal dynamics of these variants. The dynamics in the prevalence and distribution is conceivably result of de novo mutations or human migrations and subsequent evolutionary processes. In addition, ten variants designated as possibly or likely pathogenic were found, but the clinical effect of these is not yet well established and further research is warranted. All detected mutations putatively associated with mitochondrial disease in ancient mtDNA samples are in tRNA coding genes. Most of these mutations are in a mt-tRNA type (Model 2) that is characterized by loss of D-loop/T-loop interaction. Exposing pathogenic variants in ancient human populations expands our understanding of their origin and prevalence dynamics.
Collapse
Affiliation(s)
- Draga Toncheva
- Department of Medical Genetics, Medical University of Sofia, Bulgarian Academy of Science, Sofia, Bulgaria
- Bulgarian Academy of Sciences–BAS, Sofia, Bulgaria
- * E-mail:
| | - Dimitar Serbezov
- Department of Medical Genetics, Medical University of Sofia, Bulgarian Academy of Science, Sofia, Bulgaria
| | - Sena Karachanak-Yankova
- Department of Medical Genetics, Medical University of Sofia, Bulgarian Academy of Science, Sofia, Bulgaria
- Department of Genetics, Faculty of biology, Sofia University “St. Kliment Ohridski”, Sofia, Bulgaria
| | - Desislava Nesheva
- Department of Medical Genetics, Medical University of Sofia, Bulgarian Academy of Science, Sofia, Bulgaria
| |
Collapse
|
3
|
Tarnopolsky MA, Sundaram ANE, Provias J, Brady L, Sadikovic B. CPEO - Like mitochondrial myopathy associated with m.8340G>A mutation. Mitochondrion 2018; 46:69-72. [PMID: 29501485 DOI: 10.1016/j.mito.2018.02.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Revised: 02/22/2018] [Accepted: 02/23/2018] [Indexed: 11/19/2022]
Abstract
Two patients with an m.8340G>A mitochondrial DNA variant have been reported with one patient showing ptosis, ophthalmoparesis and myopathy at 53% heteroplasmy and another with pigmentary retinopathy, cataracts and sensory neural deafness and slightly higher heteroplasmy (65%). Here we report that higher muscle mutant heteroplasmy (93%) for m.8340G>A is associated with ptosis, ophthalmoparesis and mitochondrial myopathy, thus confirming the initial phenotypic association and showing that heteroplasmy per se does not explain the phenotypic spectrum of disease associated with the m.8340G>A mutation.
Collapse
Affiliation(s)
- Mark A Tarnopolsky
- Department of Pediatrics, McMaster University, Hamilton, Ontario, Canada.
| | - Arun N E Sundaram
- Department of Ophthalmology and Vision Sciences, Sunnybrook Health Sciences Center, University of Toronto, Toronto, Ontario, Canada
| | - John Provias
- Department of Pathology and Molecular Medicine, McMaster University, Hamilton, Ontario, Canada
| | - Lauren Brady
- Department of Pediatrics, McMaster University, Hamilton, Ontario, Canada
| | - Bekim Sadikovic
- Molecular Genetics Laboratory, Molecular Diagnostics Division, London Health Sciences Centre, Children's Health Research Institute, London, Ontario, Canada
| |
Collapse
|
4
|
Scarpelli M, Carreño-Gago L, Russignan A, de Luna N, Carnicer-Cáceres C, Ariatti A, Verriello L, Devigili G, Tonin P, Garcia-Arumi E, Pinós T. Identification and characterization of the novel m.8305C>T MTTK and m.4440G>A MTTM gene mutations causing mitochondrial myopathies. Neuromuscul Disord 2017; 28:137-143. [PMID: 29174468 DOI: 10.1016/j.nmd.2017.10.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Revised: 10/19/2017] [Accepted: 10/23/2017] [Indexed: 01/20/2023]
Abstract
We report on two novel mtDNA mutations in patients affected with mitochondrial myopathy. The first patient, a 44-year-old woman, had bilateral eyelid ptosis and the m.8305C>T mutation in the MTTK gene. The second patient, a 56-year-old man, had four-limb muscle weakness and the MTTM gene m.4440G>A mutation. Muscle biopsies in both patients showed ragged red fibers and numerous COX-negative fibers as well as a combined defect of complex I, III and IV activities. The two mutations were heteroplasmic and detected only in muscle tissue, with a higher mutation load in COX-negative fibers. Additionally, both mutations occurred in highly conserved mt-tRNA sites, and were not found by an in silico search in 30,589 human mtDNA sequences. Our report further expands the mutational and phenotypic spectrum of diseases associated with mutations in mitochondrial tRNA genes and reinforces the notion that mutations in mitochondrial tRNAs represent hot spots for mitochondrial myopathies in adults.
Collapse
Affiliation(s)
- Mauro Scarpelli
- Section of Neurology, Department of Neurological, Biomedical and Movement Sciences, University of Verona, Verona, Italy
| | - Lidia Carreño-Gago
- Mitochondrial Disorders Unit, Vall d'Hebron Institut de Recerca, Barcelona, Spain; Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Madrid, Spain
| | - Anna Russignan
- Section of Neurology, Department of Neurological, Biomedical and Movement Sciences, University of Verona, Verona, Italy
| | - Noemi de Luna
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Madrid, Spain; Laboratori de Malalties Neuromusculars, Institut de Recerca Hospital de la Santa Creu i Sant Pau, Universitat Autònoma de Barcelona, Spain
| | - Clara Carnicer-Cáceres
- Unidad de Metabolopatías, Servicio de Bioquímica, Hospital Universitari Vall d'Hebron, Barcelona, Spain
| | - Alessandra Ariatti
- Department of Neurosciences and Department of Onco-Haematology, University Hospitals of Modena & Reggio Emilia, Italy
| | - Lorenzo Verriello
- Division of Neurology, Department of Neuroscience, Azienda Ospedaliero Universitaria, Udine, Italy
| | - Grazia Devigili
- Division of Neurology, Department of Neuroscience, Azienda Ospedaliero Universitaria, Udine, Italy
| | - Paola Tonin
- Section of Neurology, Department of Neurological, Biomedical and Movement Sciences, University of Verona, Verona, Italy
| | - Elena Garcia-Arumi
- Mitochondrial Disorders Unit, Vall d'Hebron Institut de Recerca, Barcelona, Spain; Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Madrid, Spain; Àrea de Genètica Clínica i Molecular, Hospital Universitari Vall d'Hebron, Barcelona, Spain.
| | - Tomàs Pinós
- Mitochondrial Disorders Unit, Vall d'Hebron Institut de Recerca, Barcelona, Spain; Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Madrid, Spain.
| |
Collapse
|
5
|
Soldath P, Madsen KL, Buch AE, Duno M, Wibrand F, Vissing J. Pure exercise intolerance and ophthalmoplegia associated with the m.12,294G > A mutation in the MT-TL2 gene: a case report. BMC Musculoskelet Disord 2017; 18:419. [PMID: 29052516 PMCID: PMC5649050 DOI: 10.1186/s12891-017-1781-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Accepted: 10/12/2017] [Indexed: 12/22/2022] Open
Abstract
Background Pure exercise intolerance associated with exclusive affection of skeletal muscle is a very rare phenotype of patients with mitochondrial myopathy. Moreover, the exercise intolerance in these rare patients is yet not well explored, as most of known cases have not been assessed by objective testing, but only by interview. We report a patient with a mitochondrial DNA (mtDNA) mutation that gives rise to an exclusive myopathy associated with exercise intolerance and ophthalmoplegia. We quantified the patient’s exercise intolerance through detailed exercise testing. Case presentation A 39-year-old man presented with exercise intolerance and chronic progressive external ophthalmoplegia. Sequencing of the entire mtDNA identified a m.12,294G > A mutation in the MT-TL2 gene. The mutation was heteroplasmic in skeletal muscle (75%) while undetectable in blood, urinary sediment, and buccal mucosa as well as in tissues from the patient’s mother. The mutation affected a highly conserved site in the anticodon stem of the mitochondrial transfer RNA Leucine (CUN) molecule and lead to a severe combined respiratory chain defect. Exercise physiological studies in the patient demonstrated a significantly reduced maximal oxygen uptake of 20.4 ml O2 × min−1 × kg−1 (about half of normal) as well as threefold elevated lactate/pyruvate ratios. Conclusion The findings of our study support that the m.12,294G > A mutation is pathogenic. Likely, the mutation arose sporadically in early embryogenesis after differentiation of the mesoderm into muscle progenitor cells, leading to a pure myopathic phenotype.
Collapse
Affiliation(s)
- Patrick Soldath
- Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark. .,Department of Neurology, Copenhagen Neuromuscular Center, Rigshospitalet, Copenhagen, Denmark.
| | - Karen Lindhardt Madsen
- Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Department of Neurology, Copenhagen Neuromuscular Center, Rigshospitalet, Copenhagen, Denmark
| | - Astrid Emilie Buch
- Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Department of Neurology, Copenhagen Neuromuscular Center, Rigshospitalet, Copenhagen, Denmark
| | - Morten Duno
- Department of Clinical Genetics, Rigshospitalet, Copenhagen, Denmark
| | - Flemming Wibrand
- Department of Clinical Genetics, Rigshospitalet, Copenhagen, Denmark
| | - John Vissing
- Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Department of Neurology, Copenhagen Neuromuscular Center, Rigshospitalet, Copenhagen, Denmark
| |
Collapse
|
6
|
Gill JS, Hardy SA, Blakely EL, Hopton S, Nemeth AH, Fratter C, Poulton J, Taylor RW, Downes SM. Pigmentary retinopathy, rod-cone dysfunction and sensorineural deafness associated with a rare mitochondrial tRNA Lys (m.8340G>A) gene variant. Br J Ophthalmol 2017; 101:1298-1302. [PMID: 28729369 PMCID: PMC5574396 DOI: 10.1136/bjophthalmol-2017-310370] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Revised: 05/23/2017] [Accepted: 06/01/2017] [Indexed: 12/04/2022]
Abstract
Background/Aim The rare mitochondrial DNA (mtDNA) variant m.8340G>A has been previously reported in the literature in a single, sporadic case of mitochondrial myopathy. In this report, we aim to investigate the case of a 39-year-old male patient with sensorineural deafness who presented to the eye clinic with nyctalopia, retinal pigmentary changes and bilateral cortical cataracts. Methods The patient was examined clinically and investigated with autofluorescence, full-field electroretinography, electro-oculogram and dark adaptometry. Sequencing of the mitochondrial genome in blood and muscle tissue was followed by histochemical and biochemical analyses together with single fibre studies of a muscle biopsy to confirm a mitochondrial aetiology. Results Electrophysiology, colour testing and dark adaptometry showed significant photoreceptor dysfunction with macular involvement. Sequencing the complete mitochondrial genome revealed a rare mitochondrial tRNALys (MTTK) gene variant—m.8340G>A—which was heteroplasmic in blood (11%) and skeletal muscle (65%) and cosegregated with cytochrome c oxidase-deficient fibres in single-fibre studies. Conclusion We confirm the pathogenicity of the rare mitochondrial m.8340G>A variant the basis of single-fibre segregation studies and its association with an expanded clinical phenotype. Our case expands the phenotypic spectrum of diseases associated with mitochondrial tRNA point mutations, highlighting the importance of considering a mitochondrial diagnosis in similar cases presenting to the eye clinic and the importance of further genetic testing if standard mutational analysis does not yield a result.
Collapse
Affiliation(s)
| | - Steven A Hardy
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK
| | - Emma L Blakely
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK
| | - Sila Hopton
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK
| | - Andrea H Nemeth
- Department of Clinical Genetics, Churchill Hospital, Oxford, UK.,Nuffield Department of Clinical Neuroscience, John Radcliffe Hospital, Oxford, UK
| | - Carl Fratter
- Oxford Medical Genetics Laboratory, Churchill Hospital, Oxford, UK
| | - Joanna Poulton
- Department of Clinical Genetics, Churchill Hospital, Oxford, UK
| | - Robert W Taylor
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK
| | - Susan M Downes
- John Radcliffe Hospital, Oxford, UK.,Nuffield Department of Clinical Neuroscience, John Radcliffe Hospital, Oxford, UK
| |
Collapse
|
7
|
Scarpelli M, Todeschini A, Volonghi I, Padovani A, Filosto M. Mitochondrial diseases: advances and issues. APPLICATION OF CLINICAL GENETICS 2017; 10:21-26. [PMID: 28243136 PMCID: PMC5317313 DOI: 10.2147/tacg.s94267] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Mitochondrial diseases (MDs) are a clinically heterogeneous group of disorders caused by a dysfunction of the mitochondrial respiratory chain. They can be related to mutation of genes encoded using either nuclear DNA or mitochondrial DNA. The advent of next generation sequencing and whole exome sequencing in studying the molecular bases of MDs will bring about a revolution in the field of mitochondrial medicine, also opening the possibility of better defining pathogenic mechanisms and developing novel therapeutic approaches for these devastating disorders. The canonical rules of mitochondrial medicine remain milestones, but novel issues have been raised following the use of advanced diagnostic technologies. Rigorous validation of the novel mutations detected using deep sequencing in patients with suspected MD, and a clear definition of the natural history, outcome measures, and biomarkers that could be usefully adopted in clinical trials, are mandatory goals for the scientific community. Today, therapy is often inadequate and mostly palliative. However, important advances have been made in treating some clinical entities, eg, mitochondrial neuro-gastrointestinal encephalomyopathy, for which approaches using allogeneic hematopoietic stem cell transplantation, orthotopic liver transplantation, and carrier erythrocyte entrapped thymidine phosphorylase enzyme therapy have recently been developed. Promising new treatment methods are being identified so that researchers, clinicians, and patients can join forces to change the history of these untreatable disorders.
Collapse
Affiliation(s)
- Mauro Scarpelli
- Department of Neuroscience, Unit of Neurology, Azienda Ospedaliera Universitaria Integrata Verona, Verona, Italy
| | - Alice Todeschini
- Center for Neuromuscular Diseases and Neuropathies, Unit of Neurology, ASST "Spedali Civili", University of Brescia, Brescia, Italy
| | - Irene Volonghi
- Center for Neuromuscular Diseases and Neuropathies, Unit of Neurology, ASST "Spedali Civili", University of Brescia, Brescia, Italy
| | - Alessandro Padovani
- Center for Neuromuscular Diseases and Neuropathies, Unit of Neurology, ASST "Spedali Civili", University of Brescia, Brescia, Italy
| | - Massimiliano Filosto
- Center for Neuromuscular Diseases and Neuropathies, Unit of Neurology, ASST "Spedali Civili", University of Brescia, Brescia, Italy
| |
Collapse
|
8
|
Darin N, Hedberg-Oldfors C, Kroksmark AK, Moslemi AR, Kollberg G, Oldfors A. Benign mitochondrial myopathy with exercise intolerance in a large multigeneration family due to a homoplasmic m.3250T>C mutation in MTTL1. Eur J Neurol 2017; 24:587-593. [PMID: 28181352 DOI: 10.1111/ene.13249] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2016] [Accepted: 01/04/2017] [Indexed: 11/26/2022]
Abstract
BACKGROUND AND PURPOSE Most mitochondrial disorders with onset in early childhood are progressive and involve multiple organs. The m.3250T>C mutation in MTTL1 has previously been described in a few individuals with a possibly riboflavin-responsive myopathy and an association with sudden infant death syndrome was suspected. We describe a large family with this mutation and evaluate the effect of riboflavin treatment. METHODS Medical data were collected with the help of a standardized data collection form. Sanger sequencing was used to screen for variants in mitochondrial DNA and the proportion of the mutation was analyzed in different tissues. Biochemical and muscle morphological investigations of muscle tissue were performed in two individuals. The effect of riboflavin treatment was evaluated in two individuals. RESULTS Thirteen family members experienced exercise intolerance with fatigue and weakness. Inheritance was maternal with 100% penetrance. The course was either static or showed improvement over time. There was no evidence of other organ involvement except for a possible mild transient cardiac enlargement in one child. Muscle investigations showed isolated complex I deficiency and mitochondrial proliferation. The level of m.3250T>C was apparently 100%, i.e. homoplasmic, in all examined tissues. Riboflavin treatment showed no effect in any treated family member and there have been no cases of sudden infant death in this family. CONCLUSIONS This study illustrates the importance of considering mitochondrial disorders in the work-up of individuals with exercise intolerance and provides a better understanding of the phenotype associated with the m.3250T>C mutation in MTTL1.
Collapse
Affiliation(s)
- N Darin
- Department of Pediatrics, Sahlgrenska University Hospital, University of Gothenburg, Gothenburg
| | - C Hedberg-Oldfors
- Department of Pathology and Genetics, Sahlgrenska University Hospital, University of Gothenburg, Gothenburg
| | - A-K Kroksmark
- Department of Pediatrics, Sahlgrenska University Hospital, University of Gothenburg, Gothenburg
| | - A-R Moslemi
- Department of Pathology and Genetics, Sahlgrenska University Hospital, University of Gothenburg, Gothenburg
| | - G Kollberg
- Department of Clinical Chemistry and Transfusion Medicine, Sahlgrenska University Hospital, University of Gothenburg, Gothenburg, Sweden
| | - A Oldfors
- Department of Pathology and Genetics, Sahlgrenska University Hospital, University of Gothenburg, Gothenburg
| |
Collapse
|
9
|
Sallevelt SCEH, de Die-Smulders CEM, Hendrickx ATM, Hellebrekers DMEI, de Coo IFM, Alston CL, Knowles C, Taylor RW, McFarland R, Smeets HJM. De novo mtDNA point mutations are common and have a low recurrence risk. J Med Genet 2016; 54:73-83. [PMID: 27450679 PMCID: PMC5502310 DOI: 10.1136/jmedgenet-2016-103876] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Revised: 06/02/2016] [Accepted: 06/09/2016] [Indexed: 12/25/2022]
Abstract
Background Severe, disease-causing germline mitochondrial (mt)DNA mutations are maternally inherited or arise de novo. Strategies to prevent transmission are generally available, but depend on recurrence risks, ranging from high/unpredictable for many familial mtDNA point mutations to very low for sporadic, large-scale single mtDNA deletions. Comprehensive data are lacking for de novo mtDNA point mutations, often leading to misconceptions and incorrect counselling regarding recurrence risk and reproductive options. We aim to study the relevance and recurrence risk of apparently de novo mtDNA point mutations. Methods Systematic study of prenatal diagnosis (PND) and recurrence of mtDNA point mutations in families with de novo cases, including new and published data. ‘De novo’ based on the absence of the mutation in multiple (postmitotic) maternal tissues is preferred, but mutations absent in maternal blood only were also included. Results In our series of 105 index patients (33 children and 72 adults) with (likely) pathogenic mtDNA point mutations, the de novo frequency was 24.6%, the majority being paediatric. PND was performed in subsequent pregnancies of mothers of four de novo cases. A fifth mother opted for preimplantation genetic diagnosis because of a coexisting Mendelian genetic disorder. The mtDNA mutation was absent in all four prenatal samples and all 11 oocytes/embryos tested. A literature survey revealed 137 de novo cases, but PND was only performed for 9 (including 1 unpublished) mothers. In one, recurrence occurred in two subsequent pregnancies, presumably due to germline mosaicism. Conclusions De novo mtDNA point mutations are a common cause of mtDNA disease. Recurrence risk is low. This is relevant for genetic counselling, particularly for reproductive options. PND can be offered for reassurance.
Collapse
Affiliation(s)
- Suzanne C E H Sallevelt
- Department of Clinical Genetics, Maastricht University Medical Centre (MUMC), Maastricht, The Netherlands
| | - Christine E M de Die-Smulders
- Department of Clinical Genetics, Maastricht University Medical Centre (MUMC), Maastricht, The Netherlands.,Research School for Developmental Biology (GROW), Maastricht University, Maastricht, The Netherlands
| | - Alexandra T M Hendrickx
- Department of Clinical Genetics, Maastricht University Medical Centre (MUMC), Maastricht, The Netherlands
| | - Debby M E I Hellebrekers
- Department of Clinical Genetics, Maastricht University Medical Centre (MUMC), Maastricht, The Netherlands
| | - Irenaeus F M de Coo
- Department of Neurology, Erasmus MC-Sophia Children's Hospital Rotterdam, Rotterdam, The Netherlands
| | - Charlotte L Alston
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Newcastle upon Tyne, UK
| | - Charlotte Knowles
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Newcastle upon Tyne, UK
| | - Robert W Taylor
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Newcastle upon Tyne, UK
| | - Robert McFarland
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Newcastle upon Tyne, UK
| | - Hubert J M Smeets
- Department of Clinical Genetics, Maastricht University Medical Centre (MUMC), Maastricht, The Netherlands.,Research School for Developmental Biology (GROW), Maastricht University, Maastricht, The Netherlands.,Research School for Cardiovascular Diseases in Maastricht, CARIM, Maastricht University, Maastricht, The Netherlands
| |
Collapse
|
10
|
Born AP, Duno M, Rafiq J, Risom L, Wibrand F, Østergaard E, Vissing J. A mitochondrial tRNA(Met) mutation causing developmental delay, exercise intolerance and limb girdle phenotype with onset in early childhood. Eur J Paediatr Neurol 2015; 19:69-71. [PMID: 25468263 DOI: 10.1016/j.ejpn.2014.10.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/31/2014] [Accepted: 10/24/2014] [Indexed: 11/16/2022]
Abstract
A 10-year-old girl presented with exercise intolerance, learning difficulty, and muscle weakness in a limb girdle distribution. She had delayed achievement of motor milestones and difficulties with social interaction at pre-school age. Muscle biopsy showed no myopathic or dystrophic features, but 90% COX negative fibres and ragged blue fibres. Respiratory chain enzyme analysis in muscle showed a combined deficiency and mitochondrial DNA sequencing revealed the presence of an m.4450G>A mutation in the MT-TM gene encoding the tRNA for methionine. The mutation was only detected in mtDNA extracted from muscle and skin fibroblast, and could not be found in other tissues or in the mother. This is the second patient reported in the literature with a mitochondrial myopathy due to a mt-tRNA(Met) mutation. The first patient, a 30-year-old woman, presented with exercise intolerance, limb girdle muscle weakness, lactic acidosis, learning difficulty, and growth retardation in early childhood. Thus, the two patients exhibit strikingly overlapping phenotypes.
Collapse
Affiliation(s)
- Alfred Peter Born
- Paediatric Clinic, University of Copenhagen, Rigshospitalet, Denmark.
| | - Morten Duno
- Department of Clinical Genetics, University of Copenhagen, Rigshospitalet, Denmark
| | - Jabin Rafiq
- Neuromuscular Research Unit, University of Copenhagen, Rigshospitalet, Denmark
| | - Lotte Risom
- Department of Clinical Genetics, University of Copenhagen, Rigshospitalet, Denmark
| | - Flemming Wibrand
- Department of Clinical Genetics, University of Copenhagen, Rigshospitalet, Denmark
| | - Elsebet Østergaard
- Department of Clinical Genetics, University of Copenhagen, Rigshospitalet, Denmark
| | - John Vissing
- Neuromuscular Research Unit, University of Copenhagen, Rigshospitalet, Denmark
| |
Collapse
|
11
|
Peverelli L, Gold CA, Naini AB, Tanji K, Akman HO, Hirano M, Dimauro S. Mitochondrial myopathy with dystrophic features due to a novel mutation in the MTTM gene. Muscle Nerve 2014; 50:292-5. [PMID: 24711008 DOI: 10.1002/mus.24262] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/04/2014] [Indexed: 11/11/2022]
Abstract
INTRODUCTION A 61-year-old woman with a 5-year history of progressive muscle weakness and atrophy had a muscle biopsy characterized by a combination of dystrophic features (necrotic fibers and endomysial fibrosis) and mitochondrial alterations [ragged-red, cytochrome c oxidase (COX)-negative fibers]. METHODS Sequencing of the whole mtDNA, assessment of the mutation load in muscle and accessible nonmuscle tissues, and single fiber polymerase chain reaction. RESULTS Muscle mitochondrial DNA (mtDNA) sequencing revealed a novel heteroplasmic mutation (m.4403G>A) in the gene (MTTM) that encodes tRNA(Met). The mutation was not present in accessible nonmuscle tissues from the patient or 2 asymptomatic sisters. CONCLUSIONS The clinical features and muscle morphology in this patient are very similar to those described in a previous patient with a different mutation, also in MTTM, which suggests that mutations in this gene confer a distinctive "dystrophic" quality. This may be a diagnostic clue in patients with isolated mitochondrial myopathy.
Collapse
Affiliation(s)
- Lorenzo Peverelli
- Department of Neurology, Columbia University Medical Center, College of Physicians & Surgeons, 630 West 168th Street, New York, New York, USA
| | | | | | | | | | | | | |
Collapse
|
12
|
Kim EB, Lee SG. The complete mitochondrial genome of the Mongolian gerbil, Meriones unguiculatus (Rodentia: Muridae: Gerbillinae). Mitochondrial DNA A DNA Mapp Seq Anal 2014; 27:1457-8. [PMID: 25185794 DOI: 10.3109/19401736.2014.953091] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The complete mitochondrial genome of the Mongolian gerbil, Meriones unguiculatus, was sequenced. The 16,360 bp long genome has 37 genes typical for rodent mitogenomes, including 22 tRNA genes, 2 rRNA genes, and 13 protein-coding genes. The total GC content of the mitochondrial genome is 36.96% with the base composition of 32.61% A, 23.71% C, 13.24% G, and 30.44% T. Translational terminators of three genes (cytb, cox3, and nad4) were generated by the addition of 3' A residues to the mRNA. This novel rodent mitochondrial genome will provide comparable information for understanding the rodent mitochondrial evolution.
Collapse
Affiliation(s)
- Eun Bae Kim
- a Department of Bioinspired Science , Ewha Womans University , Seoul , Republic of Korea .,b Department of Animal Life Science , Kangwon National University , Chuncheon , Republic of Korea , and
| | - Sang-Goo Lee
- a Department of Bioinspired Science , Ewha Womans University , Seoul , Republic of Korea .,c Division of Genetics, Department of Medicine , Brigham and Women's Hospital, Harvard Medical School , Boston , MA 02115 , USA
| |
Collapse
|