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Gusic M, Prokisch H. Genetic basis of mitochondrial diseases. FEBS Lett 2021; 595:1132-1158. [PMID: 33655490 DOI: 10.1002/1873-3468.14068] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 02/17/2021] [Accepted: 02/18/2021] [Indexed: 12/13/2022]
Abstract
Mitochondrial disorders are monogenic disorders characterized by a defect in oxidative phosphorylation and caused by pathogenic variants in one of over 340 different genes. The implementation of whole-exome sequencing has led to a revolution in their diagnosis, duplicated the number of associated disease genes, and significantly increased the diagnosed fraction. However, the genetic etiology of a substantial fraction of patients exhibiting mitochondrial disorders remains unknown, highlighting limitations in variant detection and interpretation, which calls for improved computational and DNA sequencing methods, as well as the addition of OMICS tools. More intriguingly, this also suggests that some pathogenic variants lie outside of the protein-coding genes and that the mechanisms beyond the Mendelian inheritance and the mtDNA are of relevance. This review covers the current status of the genetic basis of mitochondrial diseases, discusses current challenges and perspectives, and explores the contribution of factors beyond the protein-coding regions and monogenic inheritance in the expansion of the genetic spectrum of disease.
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Affiliation(s)
- Mirjana Gusic
- Institute of Neurogenomics, Helmholtz Zentrum München, Neuherberg, Germany.,Institute of Human Genetics, Technical University of Munich, Germany.,DZHK (German Centre for Cardiovascular Research), Partner Site Munich Heart Alliance, Germany
| | - Holger Prokisch
- Institute of Neurogenomics, Helmholtz Zentrum München, Neuherberg, Germany.,Institute of Human Genetics, Technical University of Munich, Germany
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2
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Bi-allelic ADPRHL2 Mutations Cause Neurodegeneration with Developmental Delay, Ataxia, and Axonal Neuropathy. Am J Hum Genet 2018; 103:817-825. [PMID: 30401461 DOI: 10.1016/j.ajhg.2018.10.005] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2018] [Accepted: 10/02/2018] [Indexed: 12/28/2022] Open
Abstract
ADP-ribosylation is a reversible posttranslational modification used to regulate protein function. ADP-ribosyltransferases transfer ADP-ribose from NAD+ to the target protein, and ADP-ribosylhydrolases, such as ADPRHL2, reverse the reaction. We used exome sequencing to identify five different bi-allelic pathogenic ADPRHL2 variants in 12 individuals from 8 families affected by a neurodegenerative disorder manifesting in childhood or adolescence with key clinical features including developmental delay or regression, seizures, ataxia, and axonal (sensori-)motor neuropathy. ADPRHL2 was virtually absent in available affected individuals' fibroblasts, and cell viability was reduced upon hydrogen peroxide exposure, although it was rescued by expression of wild-type ADPRHL2 mRNA as well as treatment with a PARP1 inhibitor. Our findings suggest impaired protein ribosylation as another pathway that, if disturbed, causes neurodegenerative diseases.
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Fiedorczuk K, Sazanov LA. Mammalian Mitochondrial Complex I Structure and Disease-Causing Mutations. Trends Cell Biol 2018; 28:835-867. [PMID: 30055843 DOI: 10.1016/j.tcb.2018.06.006] [Citation(s) in RCA: 98] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Revised: 06/14/2018] [Accepted: 06/22/2018] [Indexed: 12/31/2022]
Abstract
Complex I has an essential role in ATP production by coupling electron transfer from NADH to quinone with translocation of protons across the inner mitochondrial membrane. Isolated complex I deficiency is a frequent cause of mitochondrial inherited diseases. Complex I has also been implicated in cancer, ageing, and neurodegenerative conditions. Until recently, the understanding of complex I deficiency on the molecular level was limited due to the lack of high-resolution structures of the enzyme. However, due to developments in single particle cryo-electron microscopy (cryo-EM), recent studies have reported nearly atomic resolution maps and models of mitochondrial complex I. These structures significantly add to our understanding of complex I mechanism and assembly. The disease-causing mutations are discussed here in their structural context.
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Affiliation(s)
- Karol Fiedorczuk
- Institute of Science and Technology Austria, Am Campus 1, Klosterneuburg 3400, Austria; Present address: The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA
| | - Leonid A Sazanov
- Institute of Science and Technology Austria, Am Campus 1, Klosterneuburg 3400, Austria.
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Hempel M, Kremer LS, Tsiakas K, Alhaddad B, Haack TB, Löbel U, Feichtinger RG, Sperl W, Prokisch H, Mayr JA, Santer R. LYRM7 - associated complex III deficiency: A clinical, molecular genetic, MR tomographic, and biochemical study. Mitochondrion 2017; 37:55-61. [DOI: 10.1016/j.mito.2017.07.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2016] [Revised: 02/18/2017] [Accepted: 07/06/2017] [Indexed: 10/19/2022]
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Kremer L, L 'hermitte-Stead C, Lesimple P, Gilleron M, Filaut S, Jardel C, Haack T, Strom T, Meitinger T, Azzouz H, Tebib N, Ogier De Baulny H, Touati G, Prokisch H, Lombès A. Severe respiratory complex III defect prevents liver adaptation to prolonged fasting. J Hepatol 2016; 65:377-85. [PMID: 27151179 PMCID: PMC5640785 DOI: 10.1016/j.jhep.2016.04.017] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/12/2015] [Revised: 04/12/2016] [Accepted: 04/20/2016] [Indexed: 12/22/2022]
Abstract
BACKGROUND & AIMS Next generation sequencing approaches have tremendously improved the diagnosis of rare genetic diseases. It may however be faced with difficult clinical interpretation of variants. Inherited enzymatic diseases provide an invaluable possibility to evaluate the function of the defective enzyme in human cell biology. This is the case for respiratory complex III, which has 11 structural subunits and requires several assembly factors. An important role of complex III in liver function is suggested by its frequent impairment in human cases of genetic complex III defects. METHODS We report the case of a child with complex III defect and acute liver dysfunction with lactic acidosis, hypoglycemia, and hyperammonemia. Mitochondrial activities were assessed in liver and fibroblasts using spectrophotometric assays. Genetic analysis was done by exome followed by Sanger sequencing. Functional complementation of defective fibroblasts was performed using lentiviral transduction followed by enzymatic analyses and expression assays. RESULTS Homozygous, truncating, mutations in LYRM7 and MTO1, two genes encoding essential mitochondrial proteins were found. Functional complementation of the complex III defect in fibroblasts demonstrated the causal role of LYRM7 mutations. Comparison of the patient's clinical history to previously reported patients with complex III defect due to nuclear DNA mutations, some actually followed by us, showed striking similarities allowing us to propose common pathophysiology. CONCLUSIONS Profound complex III defect in liver does not induce actual liver failure but impedes liver adaptation to prolonged fasting leading to severe lactic acidosis, hypoglycemia, and hyperammonemia, potentially leading to irreversible brain damage. LAY SUMMARY The diagnosis of rare genetic disease has been tremendously accelerated by the development of high throughput sequencing technology. In this paper we report the investigations that have led to identify LYRM7 mutations causing severe hepatic defect of respiratory complex III. Based on the comparison of the patient's phenotype with other cases of complex III defect, we propose that profound complex III defect in liver does not induce actual liver failure but impedes liver adaptation to prolonged fasting.
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Affiliation(s)
- Laura Kremer
- Institute of Human Genetics
Technische Universität München [München] - HelmholtzZentrum München - German Research Center for Environmental Health - 85764 Neuherberg
| | - Caroline L 'hermitte-Stead
- Institut Cochin
Université Paris Descartes - Paris 5 - Université Sorbonne Paris Cité - Institut National de la Santé et de la Recherche Médicale - U1016Centre National de la Recherche Scientifique - UMR 810422 rue Méchain, 75014 Paris
| | - Pierre Lesimple
- Institut Cochin
Université Paris Descartes - Paris 5 - Université Sorbonne Paris Cité - Institut National de la Santé et de la Recherche Médicale - U1016Centre National de la Recherche Scientifique - UMR 810422 rue Méchain, 75014 Paris
| | - Mylène Gilleron
- Institut Cochin
Université Paris Descartes - Paris 5 - Université Sorbonne Paris Cité - Institut National de la Santé et de la Recherche Médicale - U1016Centre National de la Recherche Scientifique - UMR 810422 rue Méchain, 75014 Paris,Service de Biochimie Métabolique et Centre de Génétique moléculaire et chromosomique [CHU Pitié Salpêtrière]
Assistance publique - Hôpitaux de Paris (AP-HP) - CHU Pitié-Salpêtrière [APHP] - 47-83 Boulevard de l'Hôpital 75013 Paris
| | - Sandrine Filaut
- Service de Biochimie Métabolique et Centre de Génétique moléculaire et chromosomique [CHU Pitié Salpêtrière]
Assistance publique - Hôpitaux de Paris (AP-HP) - CHU Pitié-Salpêtrière [APHP] - 47-83 Boulevard de l'Hôpital 75013 Paris
| | - Claude Jardel
- Institut Cochin
Université Paris Descartes - Paris 5 - Université Sorbonne Paris Cité - Institut National de la Santé et de la Recherche Médicale - U1016Centre National de la Recherche Scientifique - UMR 810422 rue Méchain, 75014 Paris,Service de Biochimie Métabolique et Centre de Génétique moléculaire et chromosomique [CHU Pitié Salpêtrière]
Assistance publique - Hôpitaux de Paris (AP-HP) - CHU Pitié-Salpêtrière [APHP] - 47-83 Boulevard de l'Hôpital 75013 Paris
| | - Tobias Haack
- Institute of Human Genetics
Technische Universität München [München] - HelmholtzZentrum München - German Research Center for Environmental Health - 85764 Neuherberg
| | - Tim Strom
- Institute of Human Genetics
Technische Universität München [München] - HelmholtzZentrum München - German Research Center for Environmental Health - 85764 Neuherberg
| | - Thomas Meitinger
- Institute of Human Genetics
Technische Universität München [München] - HelmholtzZentrum München - German Research Center for Environmental Health - 85764 Neuherberg
| | - Hatem Azzouz
- Service de Pédiatrie [La Rabta, Tunis]
Hopital La Rabta - Tunis - La Rabta Jebbari 1007 Tunis
| | - Neji Tebib
- Service de Pédiatrie [La Rabta, Tunis]
Hopital La Rabta - Tunis - La Rabta Jebbari 1007 Tunis
| | - Hélène Ogier De Baulny
- Service de neurologie pédiatrique et maladies métaboliques
Assistance publique - Hôpitaux de Paris (AP-HP) - Hôpital Robert Debré - Université Paris Diderot - Paris 7 - 48, boulevard Sérurier 75935 PARIS CEDEX 19
| | - Guy Touati
- Hépatologie et Maladies Héréditaires du Métabolisme
Hôpital Purpan, Toulouse - Centre de référence commun pour les maladies héréditaires du métabolisme - Hôpital des Enfants - 330, avenue de Grande-Bretagne - TSA 70034 - 31059 Toulouse cedex 9.
| | - Holger Prokisch
- Institute of Human Genetics
Technische Universität München [München] - HelmholtzZentrum München - German Research Center for Environmental Health - 85764 Neuherberg
| | - Anne Lombès
- Inserm UMR 1016, Institut Cochin, Paris, France; CNRS UMR 8104, Institut Cochin, Paris, France; Université Paris V René Descartes, Institut Cochin, Paris, France.
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Mitochondrial complex I-linked disease. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2016; 1857:938-45. [DOI: 10.1016/j.bbabio.2016.02.012] [Citation(s) in RCA: 115] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Revised: 02/16/2016] [Accepted: 02/18/2016] [Indexed: 11/22/2022]
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Wortmann SB, Koolen DA, Smeitink JA, van den Heuvel L, Rodenburg RJ. Whole exome sequencing of suspected mitochondrial patients in clinical practice. J Inherit Metab Dis 2015; 38:437-43. [PMID: 25735936 PMCID: PMC4432107 DOI: 10.1007/s10545-015-9823-y] [Citation(s) in RCA: 151] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/21/2014] [Revised: 12/04/2014] [Accepted: 02/06/2015] [Indexed: 11/25/2022]
Abstract
Mitochondrial disorders are characterized by a broad clinical spectrum. Identical clinical signs and symptoms can be caused by mutations in different mitochondrial or nuclear genes. Vice versa, the same mutation can lead to different phenotypes. Genetic syndromes and neuromuscular disorders mimicking mitochondrial disorders further complicate the diagnostic process. Whole exome sequencing (WES) is the state of the art next generation sequencing technique to identify genetic defects in mitochondrial disorders. Until recently it has mainly been used as a research tool. In this study, the use of WES in routine diagnostics is described. The WES data of 109 patients, referred under the suspicion of a mitochondrial disorder, were examined in two steps. First, the data were filtered using a virtual gene panel of genes known to be associated with mitochondrial disease. If negative, the entire exome was examined. A molecular diagnosis was achieved in 39% of the heterogeneous cohort, and in 57% of the subgroup of 42 patients with the highest suspicion for a mitochondrial disease. In addition to mutations in genes known to be associated with mitochondrial disorders (e.g. TUFM, MTFMT, FBXL4), in the subgroup of patients with the lowest suspicion for a mitochondrial disorder we found mutations in several genes associated with neuromuscular disorders (e.g. SEPN1, ACTA1) and genetic syndrome (e.g. SETBP1, ARID1B). Our results show that WES technology has been successfully implemented as a state-of-the-art, molecular diagnostic test for mitochondrial disorders as well as for the mimicking disorders in daily clinical practice. It also illustrates that clinical and biochemical phenotyping is essential for successful application of WES to diagnose individual patients.
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Affiliation(s)
- Saskia B. Wortmann
- Department of Pediatrics, Radboudumc, Nijmegen Centre for Mitochondrial Disorders (NCMD), 774 Translational Metabolic Laboratory, P.O Box 9101, 6500 HB Nijmegen, The Netherlands
| | - David A. Koolen
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Jan A. Smeitink
- Department of Pediatrics, Radboudumc, Nijmegen Centre for Mitochondrial Disorders (NCMD), 774 Translational Metabolic Laboratory, P.O Box 9101, 6500 HB Nijmegen, The Netherlands
| | - Lambert van den Heuvel
- Department of Pediatrics, Radboudumc, Nijmegen Centre for Mitochondrial Disorders (NCMD), 774 Translational Metabolic Laboratory, P.O Box 9101, 6500 HB Nijmegen, The Netherlands
| | - Richard J. Rodenburg
- Department of Pediatrics, Radboudumc, Nijmegen Centre for Mitochondrial Disorders (NCMD), 774 Translational Metabolic Laboratory, P.O Box 9101, 6500 HB Nijmegen, The Netherlands
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Björkman K, Sofou K, Darin N, Holme E, Kollberg G, Asin-Cayuela J, Holmberg Dahle KM, Oldfors A, Moslemi AR, Tulinius M. Broad phenotypic variability in patients with complex I deficiency due to mutations in NDUFS1 and NDUFV1. Mitochondrion 2015; 21:33-40. [DOI: 10.1016/j.mito.2015.01.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2014] [Revised: 01/13/2015] [Accepted: 01/13/2015] [Indexed: 10/24/2022]
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9
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Kopajtich R, Nicholls TJ, Rorbach J, Metodiev MD, Freisinger P, Mandel H, Vanlander A, Ghezzi D, Carrozzo R, Taylor RW, Marquard K, Murayama K, Wieland T, Schwarzmayr T, Mayr JA, Pearce SF, Powell CA, Saada A, Ohtake A, Invernizzi F, Lamantea E, Sommerville EW, Pyle A, Chinnery PF, Crushell E, Okazaki Y, Kohda M, Kishita Y, Tokuzawa Y, Assouline Z, Rio M, Feillet F, Mousson de Camaret B, Chretien D, Munnich A, Menten B, Sante T, Smet J, Régal L, Lorber A, Khoury A, Zeviani M, Strom TM, Meitinger T, Bertini ES, Van Coster R, Klopstock T, Rötig A, Haack TB, Minczuk M, Prokisch H. Mutations in GTPBP3 cause a mitochondrial translation defect associated with hypertrophic cardiomyopathy, lactic acidosis, and encephalopathy. Am J Hum Genet 2014; 95:708-20. [PMID: 25434004 PMCID: PMC4259976 DOI: 10.1016/j.ajhg.2014.10.017] [Citation(s) in RCA: 109] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2014] [Accepted: 10/29/2014] [Indexed: 11/22/2022] Open
Abstract
Respiratory chain deficiencies exhibit a wide variety of clinical phenotypes resulting from defective mitochondrial energy production through oxidative phosphorylation. These defects can be caused by either mutations in the mtDNA or mutations in nuclear genes coding for mitochondrial proteins. The underlying pathomechanisms can affect numerous pathways involved in mitochondrial physiology. By whole-exome and candidate gene sequencing, we identified 11 individuals from 9 families carrying compound heterozygous or homozygous mutations in GTPBP3, encoding the mitochondrial GTP-binding protein 3. Affected individuals from eight out of nine families presented with combined respiratory chain complex deficiencies in skeletal muscle. Mutations in GTPBP3 are associated with a severe mitochondrial translation defect, consistent with the predicted function of the protein in catalyzing the formation of 5-taurinomethyluridine (τm(5)U) in the anticodon wobble position of five mitochondrial tRNAs. All case subjects presented with lactic acidosis and nine developed hypertrophic cardiomyopathy. In contrast to individuals with mutations in MTO1, the protein product of which is predicted to participate in the generation of the same modification, most individuals with GTPBP3 mutations developed neurological symptoms and MRI involvement of thalamus, putamen, and brainstem resembling Leigh syndrome. Our study of a mitochondrial translation disorder points toward the importance of posttranscriptional modification of mitochondrial tRNAs for proper mitochondrial function.
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Affiliation(s)
- Robert Kopajtich
- Institute of Human Genetics, Helmholtz Zentrum München, German Research Center for Environmental Health, 85764 Neuherberg, Germany
| | | | - Joanna Rorbach
- MRC Mitochondrial Biology Unit, Hills Road, Cambridge CB2 0XY, UK
| | - Metodi D Metodiev
- INSERM U1163, Université Paris Descartes-Sorbonne Paris Cité, Institut Imagine, 75015 Paris, France
| | - Peter Freisinger
- Department of Pediatrics, Klinikum Reutlingen, 72764 Reutlingen, Germany
| | - Hanna Mandel
- Metabolic Unit, Children's Hospital, Ramban Health Care Campus, 31096 Haifa, Israel
| | - Arnaud Vanlander
- Department of Pediatric Neurology and Metabolism, University Hospital Ghent, 9000 Ghent, Belgium
| | - Daniele Ghezzi
- Unit of Molecular Neurogenetics, Fondazione IRCCS (Istituto di Ricovero e Cura a CarattereScientifico) Istituto Neurologico "Carlo Besta," 20126 Milan, Italy
| | - Rosalba Carrozzo
- Unità di Malattie Neuromuscolari e Neurodegenerative, Laboratorio di Medicina Molecolare, Dipartimento di Neuroscienze, IRCCS Ospedale Pediatrico Bambino Gesù, 00165 Roma, Italy
| | - Robert W Taylor
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Klaus Marquard
- Department of Neuropediatrics, Klinikum Stuttgart, 70176 Stuttgart, Germany
| | - Kei Murayama
- Department of Metabolism, Chiba Children's Hospital, Chiba 266-0007, Japan
| | - Thomas Wieland
- Institute of Human Genetics, Helmholtz Zentrum München, German Research Center for Environmental Health, 85764 Neuherberg, Germany; Institute of Human Genetics, Technische Universität München, 81675 Munich, Germany
| | - Thomas Schwarzmayr
- Institute of Human Genetics, Helmholtz Zentrum München, German Research Center for Environmental Health, 85764 Neuherberg, Germany; Institute of Human Genetics, Technische Universität München, 81675 Munich, Germany
| | - Johannes A Mayr
- Department of Pediatrics, Paracelsus Medical University Salzburg, 5020 Salzburg, Austria
| | - Sarah F Pearce
- MRC Mitochondrial Biology Unit, Hills Road, Cambridge CB2 0XY, UK
| | | | - Ann Saada
- Monique and Jacques Roboh Department of Genetic Research and the Department of Genetics and Metabolic Diseases, Hadassah-Hebrew University Medical Center, 91120 Jerusalem, Israel
| | - Akira Ohtake
- Department of Pediatrics, Faculty of Medicine, Saitama Medical University, Saitama 350-0495, Japan
| | - Federica Invernizzi
- Unit of Molecular Neurogenetics, Fondazione IRCCS (Istituto di Ricovero e Cura a CarattereScientifico) Istituto Neurologico "Carlo Besta," 20126 Milan, Italy
| | - Eleonora Lamantea
- Unit of Molecular Neurogenetics, Fondazione IRCCS (Istituto di Ricovero e Cura a CarattereScientifico) Istituto Neurologico "Carlo Besta," 20126 Milan, Italy
| | - Ewen W Sommerville
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Angela Pyle
- Wellcome Trust Centre for Mitochondrial Research, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne NE1 3BZ, UK
| | - Patrick F Chinnery
- Wellcome Trust Centre for Mitochondrial Research, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne NE1 3BZ, UK
| | - Ellen Crushell
- Metabolic Paediatrician, National Centre for Inherited Metabolic Disorders, Temple Street Children's University Hospital, Dublin 1, Ireland
| | - Yasushi Okazaki
- Department of Translational Research, Research Center for Genomic Medicine, Saitama Medical University, Saitama 350-1241, Japan; Department of Functional Genomics & Systems Medicine, Research Center for Genomic Medicine, Saitama Medical University, Saitama 350-1241, Japan
| | - Masakazu Kohda
- Department of Translational Research, Research Center for Genomic Medicine, Saitama Medical University, Saitama 350-1241, Japan
| | - Yoshihito Kishita
- Department of Functional Genomics & Systems Medicine, Research Center for Genomic Medicine, Saitama Medical University, Saitama 350-1241, Japan
| | - Yoshimi Tokuzawa
- Department of Functional Genomics & Systems Medicine, Research Center for Genomic Medicine, Saitama Medical University, Saitama 350-1241, Japan
| | - Zahra Assouline
- Departments of Pediatrics and Genetics, Hôpital Necker-Enfants Malades, 75015 Paris, France
| | - Marlène Rio
- Departments of Pediatrics and Genetics, Hôpital Necker-Enfants Malades, 75015 Paris, France
| | - François Feillet
- Service de médecine infantile, Hôpitald'Enfants de Brabois, CHU de Nancy, 54511 Vandoeuvre-les Nancy, France
| | | | - Dominique Chretien
- INSERM U1163, Université Paris Descartes-Sorbonne Paris Cité, Institut Imagine, 75015 Paris, France
| | - Arnold Munnich
- INSERM U1163, Université Paris Descartes-Sorbonne Paris Cité, Institut Imagine, 75015 Paris, France; Departments of Pediatrics and Genetics, Hôpital Necker-Enfants Malades, 75015 Paris, France
| | - Björn Menten
- Center for Medical Genetics, Ghent University, Ghent University Hospital, 9000 Ghent, Belgium
| | - Tom Sante
- Center for Medical Genetics, Ghent University, Ghent University Hospital, 9000 Ghent, Belgium
| | - Joél Smet
- Department of Pediatric Neurology and Metabolism, University Hospital Ghent, 9000 Ghent, Belgium
| | - Luc Régal
- Department of Pediatrics, Metabolic Center, University Hospital Leuven, 3000 Leuven, Belgium
| | - Abraham Lorber
- Department of Pediatric Cardiology, Ramban Medical Center, 31096 Haifa, Israel
| | - Asaad Khoury
- Department of Pediatric Cardiology, Ramban Medical Center, 31096 Haifa, Israel
| | - Massimo Zeviani
- MRC Mitochondrial Biology Unit, Hills Road, Cambridge CB2 0XY, UK; Unit of Molecular Neurogenetics, Fondazione IRCCS (Istituto di Ricovero e Cura a CarattereScientifico) Istituto Neurologico "Carlo Besta," 20126 Milan, Italy
| | - Tim M Strom
- Institute of Human Genetics, Helmholtz Zentrum München, German Research Center for Environmental Health, 85764 Neuherberg, Germany; Institute of Human Genetics, Technische Universität München, 81675 Munich, Germany
| | - Thomas Meitinger
- Institute of Human Genetics, Helmholtz Zentrum München, German Research Center for Environmental Health, 85764 Neuherberg, Germany; Institute of Human Genetics, Technische Universität München, 81675 Munich, Germany; DZHK (German Centre for Cardiovascular Research), partner site Munich, 81675 Munich, Germany; Munich Heart Alliance, 80802 Munich, Germany; Munich Cluster for Systems Neurology (SyNergy), 80336 Munich, Germany
| | - Enrico S Bertini
- Unità di Malattie Neuromuscolari e Neurodegenerative, Laboratorio di Medicina Molecolare, Dipartimento di Neuroscienze, IRCCS Ospedale Pediatrico Bambino Gesù, 00165 Roma, Italy
| | - Rudy Van Coster
- Department of Pediatric Neurology and Metabolism, University Hospital Ghent, 9000 Ghent, Belgium
| | - Thomas Klopstock
- Munich Cluster for Systems Neurology (SyNergy), 80336 Munich, Germany; German Research Center for Neurodegenerative Diseases (DZNE), 80336 Munich, Germany; Department of Neurology, Friedrich-Baur-Institute, Ludwig-Maximilians-University, 80336 Munich, Germany
| | - Agnès Rötig
- INSERM U1163, Université Paris Descartes-Sorbonne Paris Cité, Institut Imagine, 75015 Paris, France
| | - Tobias B Haack
- Institute of Human Genetics, Helmholtz Zentrum München, German Research Center for Environmental Health, 85764 Neuherberg, Germany; Institute of Human Genetics, Technische Universität München, 81675 Munich, Germany
| | - Michal Minczuk
- MRC Mitochondrial Biology Unit, Hills Road, Cambridge CB2 0XY, UK.
| | - Holger Prokisch
- Institute of Human Genetics, Helmholtz Zentrum München, German Research Center for Environmental Health, 85764 Neuherberg, Germany; Institute of Human Genetics, Technische Universität München, 81675 Munich, Germany.
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Kashani A, Thiffault I, Dilenge ME, Saint-Martin C, Guerrero K, Tran LT, Shoubridge E, van der Knaap MS, Braverman N, Bernard G. A homozygous mutation in the NDUFS1 gene presents with a mild cavitating leukoencephalopathy. Neurogenetics 2014; 15:161-4. [DOI: 10.1007/s10048-014-0412-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2014] [Accepted: 06/09/2014] [Indexed: 10/25/2022]
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11
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Jackson CB, Nuoffer JM, Hahn D, Prokisch H, Haberberger B, Gautschi M, Häberli A, Gallati S, Schaller A. Mutations in SDHD lead to autosomal recessive encephalomyopathy and isolated mitochondrial complex II deficiency. J Med Genet 2013; 51:170-5. [PMID: 24367056 DOI: 10.1136/jmedgenet-2013-101932] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
BACKGROUND Defects of the mitochondrial respiratory chain complex II (succinate dehydrogenase (SDH) complex) are extremely rare. Of the four nuclear encoded proteins composing complex II, only mutations in the 70 kDa flavoprotein (SDHA) and the recently identified complex II assembly factor (SDHAF1) have been found to be causative for mitochondrial respiratory chain diseases. Mutations in the other three subunits (SDHB, SDHC, SDHD) and the second assembly factor (SDHAF2) have so far only been associated with hereditary paragangliomas and phaeochromocytomas. Recessive germline mutations in SDHB have recently been associated with complex II deficiency and leukodystrophy in one patient. METHODS AND RESULTS We present the clinical and molecular investigations of the first patient with biochemical evidence of a severe isolated complex II deficiency due to compound heterozygous SDHD gene mutations. The patient presented with early progressive encephalomyopathy due to compound heterozygous p.E69 K and p.*164Lext*3 SDHD mutations. Native polyacrylamide gel electrophoresis and western blotting demonstrated an impaired complex II assembly. Complementation of a patient cell line additionally supported the pathogenicity of the novel identified mutations in SDHD. CONCLUSIONS This report describes the first case of isolated complex II deficiency due to recessive SDHD germline mutations. We therefore recommend screening for all SDH genes in isolated complex II deficiencies. It further emphasises the importance of appropriate genetic counselling to the family with regard to SDHD mutations and their role in tumorigenesis.
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Affiliation(s)
- Christopher Benjamin Jackson
- Division of Human Genetics, Departments of Paediatrics and Clinical Research, University of Bern, Bern, Switzerland
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12
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Gai X, Ghezzi D, Johnson MA, Biagosch CA, Shamseldin HE, Haack TB, Reyes A, Tsukikawa M, Sheldon CA, Srinivasan S, Gorza M, Kremer LS, Wieland T, Strom TM, Polyak E, Place E, Consugar M, Ostrovsky J, Vidoni S, Robinson AJ, Wong LJ, Sondheimer N, Salih MA, Al-Jishi E, Raab CP, Bean C, Furlan F, Parini R, Lamperti C, Mayr JA, Konstantopoulou V, Huemer M, Pierce EA, Meitinger T, Freisinger P, Sperl W, Prokisch H, Alkuraya FS, Falk MJ, Zeviani M. Mutations in FBXL4, encoding a mitochondrial protein, cause early-onset mitochondrial encephalomyopathy. Am J Hum Genet 2013; 93:482-95. [PMID: 23993194 DOI: 10.1016/j.ajhg.2013.07.016] [Citation(s) in RCA: 115] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2013] [Revised: 07/12/2013] [Accepted: 07/17/2013] [Indexed: 12/01/2022] Open
Abstract
Whole-exome sequencing and autozygosity mapping studies, independently performed in subjects with defective combined mitochondrial OXPHOS-enzyme deficiencies, identified a total of nine disease-segregating FBXL4 mutations in seven unrelated mitochondrial disease families, composed of six singletons and three siblings. All subjects manifested early-onset lactic acidemia, hypotonia, and developmental delay caused by severe encephalomyopathy consistently associated with progressive cerebral atrophy and variable involvement of the white matter, deep gray nuclei, and brainstem structures. A wide range of other multisystem features were variably seen, including dysmorphism, skeletal abnormalities, poor growth, gastrointestinal dysmotility, renal tubular acidosis, seizures, and episodic metabolic failure. Mitochondrial respiratory chain deficiency was present in muscle or fibroblasts of all tested individuals, together with markedly reduced oxygen consumption rate and hyperfragmentation of the mitochondrial network in cultured cells. In muscle and fibroblasts from several subjects, substantially decreased mtDNA content was observed. FBXL4 is a member of the F-box family of proteins, some of which are involved in phosphorylation-dependent ubiquitination and/or G protein receptor coupling. We also demonstrate that FBXL4 is targeted to mitochondria and localizes in the intermembrane space, where it participates in an approximately 400 kDa protein complex. These data strongly support a role for FBXL4 in controlling bioenergetic homeostasis and mtDNA maintenance. FBXL4 mutations are a recurrent cause of mitochondrial encephalomyopathy onset in early infancy.
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Affiliation(s)
- Xiaowu Gai
- Department of Molecular Pharmacology and Therapeutics, Loyola University Stritch School of Medicine, Maywood, IL 60153, USA
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13
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Haack T, Kopajtich R, Freisinger P, Wieland T, Rorbach J, Nicholls T, Baruffini E, Walther A, Danhauser K, Zimmermann F, Husain R, Schum J, Mundy H, Ferrero I, Strom T, Meitinger T, Taylor R, Minczuk M, Mayr J, Prokisch H. ELAC2 mutations cause a mitochondrial RNA processing defect associated with hypertrophic cardiomyopathy. Am J Hum Genet 2013; 93:211-23. [PMID: 23849775 PMCID: PMC3738821 DOI: 10.1016/j.ajhg.2013.06.006] [Citation(s) in RCA: 105] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2013] [Revised: 05/22/2013] [Accepted: 06/05/2013] [Indexed: 11/16/2022] Open
Abstract
The human mitochondrial genome encodes RNA components of its own translational machinery to produce the 13 mitochondrial-encoded subunits of the respiratory chain. Nuclear-encoded gene products are essential for all processes within the organelle, including RNA processing. Transcription of the mitochondrial genome generates large polycistronic transcripts punctuated by the 22 mitochondrial (mt) tRNAs that are conventionally cleaved by the RNase P-complex and the RNase Z activity of ELAC2 at 5' and 3' ends, respectively. We report the identification of mutations in ELAC2 in five individuals with infantile hypertrophic cardiomyopathy and complex I deficiency. We observed accumulated mtRNA precursors in affected individuals muscle and fibroblasts. Although mature mt-tRNA, mt-mRNA, and mt-rRNA levels were not decreased in fibroblasts, the processing defect was associated with impaired mitochondrial translation. Complementation experiments in mutant cell lines restored RNA processing and a yeast model provided additional evidence for the disease-causal role of defective ELAC2, thereby linking mtRNA processing to human disease.
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MESH Headings
- Amino Acid Sequence
- Cardiomyopathy, Hypertrophic/genetics
- Cardiomyopathy, Hypertrophic/metabolism
- Cardiomyopathy, Hypertrophic/pathology
- Cell Nucleus/genetics
- Cell Nucleus/metabolism
- Electron Transport/genetics
- Endoribonucleases/genetics
- Endoribonucleases/metabolism
- Female
- Fibroblasts/metabolism
- Fibroblasts/pathology
- Genetic Complementation Test
- Humans
- Infant
- Male
- Mitochondria/genetics
- Mitochondria/metabolism
- Molecular Sequence Data
- Muscles/metabolism
- Muscles/pathology
- Mutation
- Neoplasm Proteins/genetics
- Neoplasm Proteins/metabolism
- Pedigree
- RNA Processing, Post-Transcriptional
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- RNA, Mitochondrial
- RNA, Ribosomal/genetics
- RNA, Ribosomal/metabolism
- RNA, Transfer/genetics
- RNA, Transfer/metabolism
- Saccharomyces cerevisiae/genetics
- Saccharomyces cerevisiae/metabolism
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Affiliation(s)
- Tobias B. Haack
- Institute of Human Genetics, Technische Universität München, 81675 Munich, Germany
- Institute of Human Genetics, Helmholtz Zentrum München, German Research Center for Environmental Health, 85764 Neuherberg, Germany
| | - Robert Kopajtich
- Institute of Human Genetics, Helmholtz Zentrum München, German Research Center for Environmental Health, 85764 Neuherberg, Germany
| | - Peter Freisinger
- Department of Pediatrics, Klinikum Reutlingen, 72764 Reutlingen, Germany
| | - Thomas Wieland
- Institute of Human Genetics, Technische Universität München, 81675 Munich, Germany
- Institute of Human Genetics, Helmholtz Zentrum München, German Research Center for Environmental Health, 85764 Neuherberg, Germany
| | - Joanna Rorbach
- MRC Mitochondrial Biology Unit, Hills Road, Cambridge CB2 0XY, UK
| | | | - Enrico Baruffini
- Department of Life Sciences, University of Parma, 43124 Parma, Italy
| | - Anett Walther
- Institute of Human Genetics, Technische Universität München, 81675 Munich, Germany
- Institute of Human Genetics, Helmholtz Zentrum München, German Research Center for Environmental Health, 85764 Neuherberg, Germany
| | - Katharina Danhauser
- Institute of Human Genetics, Technische Universität München, 81675 Munich, Germany
| | - Franz A. Zimmermann
- Department of Pediatrics, Paracelsus Medical University Salzburg, 5020 Salzburg, Austria
| | - Ralf A. Husain
- Department of Neuropediatrics, Jena University Hospital, 07740 Jena, Germany
| | - Jessica Schum
- Institute of Human Genetics, Helmholtz Zentrum München, German Research Center for Environmental Health, 85764 Neuherberg, Germany
| | - Helen Mundy
- Centre for Inherited Metabolic Disease, Evelina Children’s Hospital, Guys and St Thomas’ NHS Foundation Trust, London SE1 7EH, UK
| | - Ileana Ferrero
- Department of Life Sciences, University of Parma, 43124 Parma, Italy
| | - Tim M. Strom
- Institute of Human Genetics, Technische Universität München, 81675 Munich, Germany
- Institute of Human Genetics, Helmholtz Zentrum München, German Research Center for Environmental Health, 85764 Neuherberg, Germany
| | - Thomas Meitinger
- Institute of Human Genetics, Technische Universität München, 81675 Munich, Germany
- Institute of Human Genetics, Helmholtz Zentrum München, German Research Center for Environmental Health, 85764 Neuherberg, Germany
- DZHK (German Centre for Cardiovascular Research), partner site Munich, 81675 Munich, Germany
- Munich Heart Alliance, 80802 Munich, Germany
| | - Robert W. Taylor
- Wellcome Trust Centre for Mitochondrial Research, Institute for Ageing and Health, The Medical School, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Michal Minczuk
- MRC Mitochondrial Biology Unit, Hills Road, Cambridge CB2 0XY, UK
| | - Johannes A. Mayr
- Department of Pediatrics, Paracelsus Medical University Salzburg, 5020 Salzburg, Austria
| | - Holger Prokisch
- Institute of Human Genetics, Technische Universität München, 81675 Munich, Germany
- Institute of Human Genetics, Helmholtz Zentrum München, German Research Center for Environmental Health, 85764 Neuherberg, Germany
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14
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Dames S, Chou LS, Xiao Y, Wayman T, Stocks J, Singleton M, Eilbeck K, Mao R. The development of next-generation sequencing assays for the mitochondrial genome and 108 nuclear genes associated with mitochondrial disorders. J Mol Diagn 2013; 15:526-34. [PMID: 23665194 DOI: 10.1016/j.jmoldx.2013.03.005] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2013] [Revised: 03/08/2013] [Accepted: 03/15/2013] [Indexed: 01/25/2023] Open
Abstract
Sanger sequencing of multigenic disorders can be technically challenging, time consuming, and prohibitively expensive. High-throughput next-generation sequencing (NGS) can provide a cost-effective method for sequencing targeted genes associated with multigenic disorders. We have developed a NGS clinical targeted gene assay for the mitochondrial genome and for 108 selected nuclear genes associated with mitochondrial disorders. Mitochondrial disorders have a reported incidence of 1 in 5000 live births, encompass a broad range of phenotypes, and are attributed to mutations in the mitochondrial and nuclear genomes. Approximately 20% of mitochondrial disorders result from mutations in mtDNA, with the remaining 80% found in nuclear genes that affect mtDNA levels or mitochondrion protein assembly. In our NGS approach, the 16,569-bp mtDNA is enriched by long-range PCR and the 108 nuclear genes (which represent 1301 amplicons and 680 kb) are enriched by RainDance emulsion PCR. Sequencing is performed on Illumina HiSeq 2000 or MiSeq platforms, and bioinformatics analysis is performed using commercial and in-house developed bioinformatics pipelines. A total of 16 validation and 13 clinical samples were examined. All previously reported variants associated with mitochondrial disorders were found in validation samples, and 5 of the 13 clinical samples were found to have mutations associated with mitochondrial disorders in either the mitochondrial genome or the 108 nuclear genes. All variants were confirmed by Sanger sequencing.
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Affiliation(s)
- Shale Dames
- Institute for Clinical and Experimental Pathology, ARUP Laboratories, Salt Lake City, UT 84108, USA.
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15
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Loss-of-function mutations in MGME1 impair mtDNA replication and cause multisystemic mitochondrial disease. Nat Genet 2013; 45:214-9. [PMID: 23313956 DOI: 10.1038/ng.2501] [Citation(s) in RCA: 166] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2012] [Accepted: 11/28/2012] [Indexed: 12/17/2022]
Abstract
Known disease mechanisms in mitochondrial DNA (mtDNA) maintenance disorders alter either the mitochondrial replication machinery (POLG, POLG2 and C10orf2) or the biosynthesis pathways of deoxyribonucleoside 5'-triphosphates for mtDNA synthesis. However, in many of these disorders, the underlying genetic defect has yet to be discovered. Here, we identify homozygous nonsense and missense mutations in the orphan gene C20orf72 in three families with a mitochondrial syndrome characterized by external ophthalmoplegia, emaciation and respiratory failure. Muscle biopsies showed mtDNA depletion and multiple mtDNA deletions. C20orf72, hereafter MGME1 (mitochondrial genome maintenance exonuclease 1), encodes a mitochondrial RecB-type exonuclease belonging to the PD-(D/E)XK nuclease superfamily. We show that MGME1 cleaves single-stranded DNA and processes DNA flap substrates. Fibroblasts from affected individuals do not repopulate after chemically induced mtDNA depletion. They also accumulate intermediates of stalled replication and show increased levels of 7S DNA, as do MGME1-depleted cells. Thus, we show that MGME1-mediated mtDNA processing is essential for mitochondrial genome maintenance.
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16
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Haack TB, Rolinski B, Haberberger B, Zimmermann F, Schum J, Strecker V, Graf E, Athing U, Hoppen T, Wittig I, Sperl W, Freisinger P, Mayr JA, Strom TM, Meitinger T, Prokisch H. Homozygous missense mutation in BOLA3 causes multiple mitochondrial dysfunctions syndrome in two siblings. J Inherit Metab Dis 2013; 36:55-62. [PMID: 22562699 DOI: 10.1007/s10545-012-9489-7] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/07/2012] [Revised: 03/22/2012] [Accepted: 04/10/2012] [Indexed: 11/30/2022]
Abstract
Defects of mitochondrial oxidative phosphorylation constitute a clinical and genetic heterogeneous group of disorders affecting multiple organ systems at varying age. Biochemical analysis of biopsy material demonstrates isolated or combined deficiency of mitochondrial respiratory chain enzyme complexes. Co-occurrence of impaired activity of the pyruvate dehydrogenase complex has been rarely reported so far and is not yet fully understood. We investigated two siblings presenting with severe neonatal lactic acidosis, hypotonia, and intractable cardiomyopathy; both died within the first months of life. Muscle biopsy revealed a peculiar biochemical defect consisting of a combined deficiency of respiratory chain complexes I, II, and II+III accompanied by a defect of the pyruvate dehydrogenase complex. Joint exome analysis of both affected siblings uncovered a homozygous missense mutation in BOLA3. The causal role of the mutation was validated by lentiviral-mediated expression of the mitochondrial isoform of wildtype BOLA3 in patient fibroblasts, which lead to an increase of both residual enzyme activities and lipoic acid levels. Our results suggest that BOLA3 plays a crucial role in the biogenesis of iron-sulfur clusters necessary for proper function of respiratory chain and 2-oxoacid dehydrogenase complexes. We conclude that broad sequencing approaches combined with appropriate prioritization filters and experimental validation enable efficient molecular diagnosis and have the potential to discover new disease loci.
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Affiliation(s)
- Tobias B Haack
- Institute of Human Genetics, Technische Universität München, Trogerstrasse 32, 81675 Munich, Germany
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17
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DHTKD1 mutations cause 2-aminoadipic and 2-oxoadipic aciduria. Am J Hum Genet 2012; 91:1082-7. [PMID: 23141293 DOI: 10.1016/j.ajhg.2012.10.006] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2012] [Revised: 08/31/2012] [Accepted: 10/12/2012] [Indexed: 11/24/2022] Open
Abstract
Abnormalities in metabolite profiles are valuable indicators of underlying pathologic conditions at the molecular level. However, their interpretation relies on detailed knowledge of the pathways, enzymes, and genes involved. Identification and characterization of their physiological function are therefore crucial for our understanding of human disease: they can provide guidance for therapeutic intervention and help us to identify suitable biomarkers for monitoring associated disorders. We studied two individuals with 2-aminoadipic and 2-oxoadipic aciduria, a metabolic condition that is still unresolved at the molecular level. This disorder has been associated with varying neurological symptoms. Exome sequencing of a single affected individual revealed compound heterozygosity for an initiating methionine mutation (c.1A>G) and a missense mutation (c.2185G>A [p.Gly729Arg]) in DHTKD1. This gene codes for dehydrogenase E1 and transketolase domain-containing protein 1, which is part of a 2-oxoglutarate-dehydrogenase-complex-like protein. Sequence analysis of a second individual identified the same missense mutation together with a nonsense mutation (c.1228C>T [p.Arg410(∗)]) in DHTKD1. Increased levels of 2-oxoadipate in individual-derived fibroblasts normalized upon lentiviral expression of the wild-type DHTKD1 mRNA. Moreover, investigation of L-lysine metabolism showed an accumulation of deuterium-labeled 2-oxoadipate only in noncomplemented cells, demonstrating that DHTKD1 codes for the enzyme mediating the last unresolved step in the L-lysine-degradation pathway. All together, our results establish mutations in DHTKD1 as a cause of human 2-aminoadipic and 2-oxoadipic aciduria via impaired turnover of decarboxylation 2-oxoadipate to glutaryl-CoA.
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18
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Danhauser K, Sauer SW, Haack TB, Wieland T, Staufner C, Graf E, Zschocke J, Strom TM, Traub T, Okun JG, Meitinger T, Hoffmann GF, Prokisch H, Kölker S. DHTKD1 mutations cause 2-aminoadipic and 2-oxoadipic aciduria. Am J Hum Genet 2012. [PMID: 23141293 DOI: 10.1016/j.ajhg.2012.10.006/s0002-9297(12)00528-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Abnormalities in metabolite profiles are valuable indicators of underlying pathologic conditions at the molecular level. However, their interpretation relies on detailed knowledge of the pathways, enzymes, and genes involved. Identification and characterization of their physiological function are therefore crucial for our understanding of human disease: they can provide guidance for therapeutic intervention and help us to identify suitable biomarkers for monitoring associated disorders. We studied two individuals with 2-aminoadipic and 2-oxoadipic aciduria, a metabolic condition that is still unresolved at the molecular level. This disorder has been associated with varying neurological symptoms. Exome sequencing of a single affected individual revealed compound heterozygosity for an initiating methionine mutation (c.1A>G) and a missense mutation (c.2185G>A [p.Gly729Arg]) in DHTKD1. This gene codes for dehydrogenase E1 and transketolase domain-containing protein 1, which is part of a 2-oxoglutarate-dehydrogenase-complex-like protein. Sequence analysis of a second individual identified the same missense mutation together with a nonsense mutation (c.1228C>T [p.Arg410(∗)]) in DHTKD1. Increased levels of 2-oxoadipate in individual-derived fibroblasts normalized upon lentiviral expression of the wild-type DHTKD1 mRNA. Moreover, investigation of L-lysine metabolism showed an accumulation of deuterium-labeled 2-oxoadipate only in noncomplemented cells, demonstrating that DHTKD1 codes for the enzyme mediating the last unresolved step in the L-lysine-degradation pathway. All together, our results establish mutations in DHTKD1 as a cause of human 2-aminoadipic and 2-oxoadipic aciduria via impaired turnover of decarboxylation 2-oxoadipate to glutaryl-CoA.
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Affiliation(s)
- Katharina Danhauser
- Institute of Human Genetics, Technische Universität München, 81675 Munich, Germany
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