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Kong LY, Wu YZ, Cheng RQ, Wang PH, Peng BW. Role of Mutations of Mitochondrial Aminoacyl-tRNA Synthetases Genes on Epileptogenesis. Mol Neurobiol 2023; 60:5482-5492. [PMID: 37316759 DOI: 10.1007/s12035-023-03429-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Accepted: 06/05/2023] [Indexed: 06/16/2023]
Abstract
Mitochondria are the structures in cells that are responsible for producing energy. They contain a specific translation unit for synthesizing mitochondria-encoded respiratory chain components: the mitochondrial DNA (mt DNA). Recently, a growing number of syndromes associated with the dysfunction of mt DNA translation have been reported. However, the functions of these diseases still need to be precise and thus attract much attention. Mitochondrial tRNAs (mt tRNAs) are encoded by mt DNA; they are the primary cause of mitochondrial dysfunction and are associated with a wide range of pathologies. Previous research has shown the role of mt tRNAs in the epileptic mechanism. This review will focus on the function of mt tRNA and the role of mitochondrial aminoacyl-tRNA synthetase (mt aaRS) in order to summarize some common relevant mutant genes of mt aaRS that cause epilepsy and the specific symptoms of the disease they cause.
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Affiliation(s)
- Ling-Yue Kong
- Department of Physiology, School of Basic Medical Sciences, Wuhan University, Wuhan, China
| | - Yi-Ze Wu
- Department of Physiology, School of Basic Medical Sciences, Wuhan University, Wuhan, China
| | - Run-Qi Cheng
- Department of Physiology, School of Basic Medical Sciences, Wuhan University, Wuhan, China
| | - Pei-Han Wang
- Department of Physiology, School of Basic Medical Sciences, Wuhan University, Wuhan, China
| | - Bi-Wen Peng
- Department of Physiology, School of Basic Medical Sciences, Wuhan University, Wuhan, China.
- Department of Physiology, Hubei Provincial Key Laboratory of Developmentally Originated Disease, School of Basic Medical Sciences, Wuhan University, Donghu Rd185#, Wuhan, 430071, Hubei, China.
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Distelmaier F, Klopstock T. Neuroimaging in mitochondrial disease. HANDBOOK OF CLINICAL NEUROLOGY 2023; 194:173-185. [PMID: 36813312 DOI: 10.1016/b978-0-12-821751-1.00016-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/22/2023]
Abstract
The anatomic complexity of the brain in combination with its high energy demands makes this organ specifically vulnerable to defects of mitochondrial oxidative phosphorylation. Therefore, neurodegeneration is a hallmark of mitochondrial diseases. The nervous system of affected individuals typically shows selective regional vulnerability leading to distinct patterns of tissue damage. A classic example is Leigh syndrome, which causes symmetric alterations of basal ganglia and brain stem. Leigh syndrome can be caused by different genetic defects (>75 known disease genes) with variable disease onset ranging from infancy to adulthood. Other mitochondrial diseases are characterized by focal brain lesions, which is a core feature of MELAS syndrome (mitochondrial encephalopathy, lactic acidosis, and stroke-like episodes). Apart from gray matter, also white matter can be affected by mitochondrial dysfunction. White matter lesions vary depending on the underlying genetic defect and may progress into cystic cavities. In view of the recognizable patterns of brain damage in mitochondrial diseases, neuroimaging techniques play a key role in diagnostic work-up. In the clinical setting, magnetic resonance imaging (MRI) and MR spectroscopy (MRS) are the mainstay of diagnostic work-up. Apart from visualization of brain anatomy, MRS allows the detection of metabolites such as lactate, which is of specific interest in the context of mitochondrial dysfunction. However, it is important to note that findings like symmetric basal ganglia lesions on MRI or a lactate peak on MRS are not specific, and that there is a broad range of disorders that can mimic mitochondrial diseases on neuroimaging. In this chapter, we will review the spectrum of neuroimaging findings in mitochondrial diseases and discuss important differential diagnoses. Moreover, we will give an outlook on novel biomedical imaging tools that may provide interesting insights into mitochondrial disease pathophysiology.
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Affiliation(s)
- Felix Distelmaier
- Department of General Pediatrics, Neonatology and Pediatric Cardiology, University Children's Hospital Düsseldorf, Medical Faculty, Heinrich Heine University, Düsseldorf, Germany.
| | - Thomas Klopstock
- Department of Neurology, Friedrich-Baur-Institute, University Hospital, Ludwig-Maximilians-Universität (LMU) München, Munich, Germany; German Center for Neurodegenerative Diseases (DZNE), Munich, Germany; Munich Cluster for Systems Neurology (SyNergy), Munich, Germany; German Network for mitochondrial disorders (mitoNET), Munich, Germany
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3
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Del Greco C, Antonellis A. The Role of Nuclear-Encoded Mitochondrial tRNA Charging Enzymes in Human Inherited Disease. Genes (Basel) 2022; 13:2319. [PMID: 36553587 PMCID: PMC9777667 DOI: 10.3390/genes13122319] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Revised: 11/30/2022] [Accepted: 12/02/2022] [Indexed: 12/13/2022] Open
Abstract
Aminoacyl-tRNA synthetases (ARSs) are highly conserved essential enzymes that charge tRNA with cognate amino acids-the first step of protein synthesis. Of the 37 nuclear-encoded human ARS genes, 17 encode enzymes are exclusively targeted to the mitochondria (mt-ARSs). Mutations in nuclear mt-ARS genes are associated with rare, recessive human diseases with a broad range of clinical phenotypes. While the hypothesized disease mechanism is a loss-of-function effect, there is significant clinical heterogeneity among patients that have mutations in different mt-ARS genes and also among patients that have mutations in the same mt-ARS gene. This observation suggests that additional factors are involved in disease etiology. In this review, we present our current understanding of diseases caused by mutations in the genes encoding mt-ARSs and propose explanations for the observed clinical heterogeneity.
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Affiliation(s)
- Christina Del Greco
- Department of Human Genetics, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Anthony Antonellis
- Department of Human Genetics, University of Michigan Medical School, Ann Arbor, MI 48109, USA
- Department of Neurology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
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Laugwitz L, Seibt A, Herebian D, Peralta S, Kienzle I, Buchert R, Falb R, Gauck D, Müller A, Grimmel M, Beck-Woedel S, Kern J, Daliri K, Katibeh P, Danhauser K, Leiz S, Alesi V, Baertling F, Vasco G, Steinfeld R, Wagner M, Caglayan AO, Gumus H, Burmeister M, Mayatepek E, Martinelli D, Tamhankar PM, Tamhankar V, Joset P, Steindl K, Rauch A, Bonnen PE, Froukh T, Groeschel S, Krägeloh-Mann I, Haack TB, Distelmaier F. Human COQ4 deficiency: delineating the clinical, metabolic and neuroimaging phenotypes. J Med Genet 2022; 59:878-887. [PMID: 34656997 PMCID: PMC9807242 DOI: 10.1136/jmedgenet-2021-107729] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Accepted: 09/26/2021] [Indexed: 01/04/2023]
Abstract
BACKGROUND Human coenzyme Q4 (COQ4) is essential for coenzyme Q10 (CoQ10) biosynthesis. Pathogenic variants in COQ4 cause childhood-onset neurodegeneration. We aimed to delineate the clinical spectrum and the cellular consequences of COQ4 deficiency. METHODS Clinical course and neuroradiological findings in a large cohort of paediatric patients with COQ4 deficiency were analysed. Functional studies in patient-derived cell lines were performed. RESULTS We characterised 44 individuals from 36 families with COQ4 deficiency (16 newly described). A total of 23 different variants were identified, including four novel variants in COQ4. Correlation analyses of clinical and neuroimaging findings revealed three disease patterns: type 1: early-onset phenotype with neonatal brain anomalies and epileptic encephalopathy; type 2: intermediate phenotype with distinct stroke-like lesions; and type 3: moderate phenotype with non-specific brain pathology and a stable disease course. The functional relevance of COQ4 variants was supported by in vitro studies using patient-derived fibroblast lines. Experiments revealed significantly decreased COQ4 protein levels, reduced levels of cellular CoQ10 and elevated levels of the metabolic intermediate 6-demethoxyubiquinone. CONCLUSION Our study describes the heterogeneous clinical presentation of COQ4 deficiency and identifies phenotypic subtypes. Cell-based studies support the pathogenic characteristics of COQ4 variants. Due to the insufficient clinical response to oral CoQ10 supplementation, alternative treatment strategies are warranted.
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Affiliation(s)
- Lucia Laugwitz
- Institute of Medical Genetics and Applied Genomics, University of Tübingen, Tübingen, Germany,Department of Neuropediatrics, Developmental Neurology and Social Pediatrics, University of Tübingen, Tübingen, Germany
| | - Annette Seibt
- Department of General Pediatrics, Neonatology and Pediatric Cardiology, Medical Faculty, Heinrich-Heine-University, Düsseldorf, Germany
| | - Diran Herebian
- Department of General Pediatrics, Neonatology and Pediatric Cardiology, Medical Faculty, Heinrich-Heine-University, Düsseldorf, Germany
| | - Susana Peralta
- Institute of Medical Genetics and Applied Genomics, University of Tübingen, Tübingen, Germany
| | - Imke Kienzle
- Department of Neuropediatrics, Developmental Neurology and Social Pediatrics, University of Tübingen, Tübingen, Germany
| | - Rebecca Buchert
- Institute of Medical Genetics and Applied Genomics, University of Tübingen, Tübingen, Germany
| | - Ruth Falb
- Institute of Medical Genetics and Applied Genomics, University of Tübingen, Tübingen, Germany
| | - Darja Gauck
- Institute of Medical Genetics and Applied Genomics, University of Tübingen, Tübingen, Germany
| | - Amelie Müller
- Institute of Medical Genetics and Applied Genomics, University of Tübingen, Tübingen, Germany
| | - Mona Grimmel
- Institute of Medical Genetics and Applied Genomics, University of Tübingen, Tübingen, Germany
| | - Stefanie Beck-Woedel
- Institute of Medical Genetics and Applied Genomics, University of Tübingen, Tübingen, Germany
| | - Jan Kern
- Department of Neuropediatrics, Developmental Neurology and Social Pediatrics, University of Tübingen, Tübingen, Germany
| | - Karim Daliri
- Child Developmental Center, Shiraz University of Medical Sciences, Shiraz, Iran,Institute for Neurophysiology, University of Cologne, Medical Faculty, Cologne, Germany
| | - Pegah Katibeh
- Child Developmental Center, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Katharina Danhauser
- Institute of Human Genetics, Technische Universität München, Munich, Germany,Helmholtz Zentrum Muenchen, Deutsches Forschungszentrum fuer Gesundheit und Umwelt (GmbH), Neuherberg, Germany
| | - Steffen Leiz
- Pediatric Neurology, Department of Pediatrics, Klinikum Dritter Orden, Munich, Germany
| | - Viola Alesi
- Laboratory of Medical Genetics, Bambino Gesù Children’s Hospital, IRCCS, Rome, Italy
| | - Fabian Baertling
- Department of General Pediatrics, Neonatology and Pediatric Cardiology, Medical Faculty, Heinrich-Heine-University, Düsseldorf, Germany
| | - Gessica Vasco
- Department of Neuroscience and Neurorehabilitation, Unit of Neurorehabilitation, IRCCS Bambino Gesù Children’s Hospital, Rome, Italy
| | | | - Matias Wagner
- Institute of Human Genetics, Technische Universität München, Munich, Germany,Helmholtz Zentrum Muenchen, Deutsches Forschungszentrum fuer Gesundheit und Umwelt (GmbH), Neuherberg, Germany
| | - Ahmet Okay Caglayan
- Department of Medical Genetics, School of Medicine, Dokuz Eylul University, Izmir, Turkey
| | - Hakan Gumus
- Department of Pediatrics, Erciyes University School of Medicine, Kayseri, Turkey
| | - Margit Burmeister
- Michigan Neuroscience Institute, University of Michigan, Ann Arbor, Michigan, USA
| | - Ertan Mayatepek
- Department of General Pediatrics, Neonatology and Pediatric Cardiology, Medical Faculty, Heinrich-Heine-University, Düsseldorf, Germany
| | - Diego Martinelli
- Division of Metabolism, Bambino Gesù Children’s Hospital IRCCS, Rome, Italy
| | | | | | - Pascal Joset
- Medical Genetics, Institute of Medical Genetics and Pathology, University Hospital Basel, 4056 Basel, Switzerland
| | - Katharina Steindl
- Institute of Medical Genetics, University of Zurich, Zurich, Switzerland
| | - Anita Rauch
- Institute of Medical Genetics, University of Zurich, Zurich, Switzerland
| | - Penelope E Bonnen
- Human Genome Sequencing Center, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
| | - Tawfiq Froukh
- Department of Biotechnology and Genetic Engineering, Philadelphia University, Amman, Jordan
| | - Samuel Groeschel
- Department of Neuropediatrics, Developmental Neurology and Social Pediatrics, University of Tübingen, Tübingen, Germany
| | - Ingeborg Krägeloh-Mann
- Department of Neuropediatrics, Developmental Neurology and Social Pediatrics, University of Tübingen, Tübingen, Germany
| | - Tobias B Haack
- Institute of Medical Genetics and Applied Genomics, University of Tübingen, Tübingen, Germany,Center for Rare Disease, University of Tübingen, Tübingen, Germany
| | - Felix Distelmaier
- Department of General Pediatrics, Neonatology and Pediatric Cardiology, Medical Faculty, Heinrich-Heine-University, Düsseldorf, Germany
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Wu XH, Lin SZ, Zhou YQ, Wang WQ, Li JY, Chen QD. VARS2 gene mutation leading to overall developmental delay in a child with epilepsy: A case report. World J Clin Cases 2022; 10:8749-8754. [PMID: 36157797 PMCID: PMC9453344 DOI: 10.12998/wjcc.v10.i24.8749] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Revised: 07/02/2022] [Accepted: 07/22/2022] [Indexed: 02/05/2023] Open
Abstract
BACKGROUND The mitochondrial respiratory chain defects have become the most common cause of neurometabolic disorders in children and adults, which can occur at any time in life, often associated with neurological dysfunction, and lead to chronic disability and premature death. Approximately one-third of patients with mitochondrial disease have biochemical defects involving multiple respiratory chain complexes, suggesting defects in protein synthesis within the mitochondria. We here report a child with VARS2 gene mutations causing mitochondrial disease.
CASE SUMMARY A girl, aged 3 years and 4 mo, had been unable to sit and crawl alone since birth, with obvious seizures and microcephaly. Brain magnetic resonance imaging showed symmetrical, flaky, long T1-weighted and low T2-weighted signals in the posterior part of the bilateral putamen with a high signal shadow. T2 fluid-attenuated inversion recovery imaging showed a slightly high signal and diffusion-weighted imaging showed an obvious high signal. Whole-exome gene sequencing revealed a compound heterozygous mutation in the VARS2 gene, c.1163(exon11)C>T and c.1940(exon20)C>T, which was derived from the parents. The child was diagnosed with combined oxidative phosphorylation deficiency type 20.
CONCLUSION In this patient, mitochondrial disorders including Leigh syndrome and MELAS syndrome (mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes) were ruled out, and combined oxidative phosphorylation deficiency type 20 was diagnosed, expanding the phenotypic spectrum of the disease.
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Affiliation(s)
- Xiao-Hui Wu
- Department of Neurology, Quanzhou Children's Hospital, Quanzhou 362000, Fujian Province, China
| | - Shuang-Zhu Lin
- Diagnosis and Treatment Center for Children, The Affiliated Hospital of Changchun University of Chinese Medicine, Changchun 130103, Jilin Province, China
| | - Yan-Qiu Zhou
- Diagnosis and Treatment Center for Children, The Affiliated Hospital of Changchun University of Chinese Medicine, Changchun 130103, Jilin Province, China
| | - Wan-Qi Wang
- Pediatrics of Traditional Chinese Medicine, College of Traditional Chinese Medicine, Changchun University of Chinese Medicine, Changchun 130117, Jilin province, China
| | - Jia-Yi Li
- Pediatrics of Traditional Chinese Medicine, College of Traditional Chinese Medicine, Changchun University of Chinese Medicine, Changchun 130117, Jilin province, China
| | - Qian-Dui Chen
- College of Integrated Chinese and Western Medicine, Changchun University of Chinese Medicine, Changchun 130117, Jilin Province, China
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VARS2 Depletion Leads to Activation of the Integrated Stress Response and Disruptions in Mitochondrial Fatty Acid Oxidation. Int J Mol Sci 2022; 23:ijms23137327. [PMID: 35806332 PMCID: PMC9267100 DOI: 10.3390/ijms23137327] [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: 06/10/2022] [Revised: 06/28/2022] [Accepted: 06/29/2022] [Indexed: 11/26/2022] Open
Abstract
Mutations in mitochondrial aminoacyl-tRNA synthetases (mtARSs) have been reported in patients with mitochondriopathies: most commonly encephalopathy, but also cardiomyopathy. Through a GWAS, we showed possible associations between mitochondrial valyl-tRNA synthetase (VARS2) dysregulations and non-ischemic cardiomyopathy. We aimed to investigate the possible consequences of VARS2 depletion in zebrafish and cultured HEK293A cells. Transient VARS2 loss-of-function was induced in zebrafish embryos using Morpholinos. The enzymatic activity of VARS2 was measured in VARS2-depleted cells via northern blot. Heterozygous VARS2 knockout was established in HEK293A cells using CRISPR/Cas9 technology. BN-PAGE and SDS-PAGE were used to investigate electron transport chain (ETC) complexes, and the oxygen consumption rate and extracellular acidification rate were measured using a Seahorse XFe96 Analyzer. The activation of the integrated stress response (ISR) and possible disruptions in mitochondrial fatty acid oxidation (FAO) were explored using RT-qPCR and western blot. Zebrafish embryos with transient VARS2 loss-of-function showed features of heart failure as well as indications of CNS and skeletal muscle involvements. The enzymatic activity of VARS2 was significantly reduced in VARS2-depleted cells. Heterozygous VARS2-knockout cells showed a rearrangement of ETC complexes in favor of complexes III2, III2 + IV, and supercomplexes without significant respiratory chain deficiencies. These cells also showed the enhanced activation of the ISR, as indicated by increased eIF-2α phosphorylation and a significant increase in the transcript levels of ATF4, ATF5, and DDIT3 (CHOP), as well as disruptions in FAO. The activation of the ISR and disruptions in mitochondrial FAO may underlie the adaptive changes in VARS2-depleted cells.
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Mitochondrial-Related Transcriptome Feature Correlates with Prognosis, Vascular Invasion, Tumor Microenvironment, and Treatment Response in Hepatocellular Carcinoma. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2022; 2022:1592905. [PMID: 35535359 PMCID: PMC9078845 DOI: 10.1155/2022/1592905] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Accepted: 03/30/2022] [Indexed: 01/17/2023]
Abstract
Background Hepatocellular carcinoma (HCC) is the most common subtype of primary liver cancer, which was highly correlated with metabolic dysfunction. Nevertheless, the association between nuclear mitochondrial-related transcriptome and HCC remained unclear. Materials and Methods A total of 147 nuclear mitochondrial-related genes (NMRGs) were downloaded from the MITOMAP: A Human Mitochondrial Genome Database. The training dataset was downloaded from The Cancer Genome Atlas (TCGA), while validation datasets were retrieved from the International Cancer Genome Consortium (ICGC) and Gene Expression Omnibus (GEO). The univariate and multivariate, and least absolute shrinkage and selection operator (LASSO) Cox regression analyses were applied to construct a NMRG signature, and the value of area under receiver operating characteristic curve (AUC) was utilized to assess the signature and nomogram. Then, data from the Genomics of Drug Sensitivity in Cancer (GDSC) were used for the evaluation of chemotherapy response in HCC. Results Functional enrichment of differentially expressed genes (DEGs) between HCC and paired normal tissue samples demonstrated that mitochondrial dysfunction was significantly associated with HCC development. Survival analysis showed a total of 35 NMRGs were significantly correlated with overall survival (OS) of HCC, and the LASSO Cox regression analysis further identified a 25-NMRG signature and corresponding prognosis score based on their transcriptional profiling. HCC patients were divided into high- and low-risk groups according to the median prognosis score, and high-risk patients had significantly worse OS (median OS: 27.50 vs. 83.18 months, P < 0.0001). The AUC values for OS at 1, 3, and 5 years were 0.79, 0.77, and 0.77, respectively. The prognostic capacity of NMRG signature was verified in the GSE14520 dataset and ICGC-HCC cohort. Besides, the NMRG signature outperformed each NMRG and clinical features in prognosis prediction and could also differentiate whether patients presented with vascular invasions (VIs) or not. Subsequently, a prognostic nomogram (C-index: 0.753, 95% CI: 0.703~0.804) by the integration of age, tumor metastasis, and NMRG prognosis score was constructed with the AUC values for OS at 1, 3, and 5 years were 0.82, 0.81, and 0.82, respectively. Notably, significant enrichment of regulatory and follicular helper T cells in high-risk group indicated the potential treatment of immune checkpoint inhibitors for these patients. Interestingly, the NMRG signature could also identify the potential responders of sorafenib or transcatheter arterial chemoembolization (TACE) treatment. Additionally, HCC patients in high-risk group appeared to be more sensitive to cisplatin, vorinostat, and methotrexate, reversely, patients in low-risk group had significantly higher sensitivity to paclitaxel and bleomycin instead. Conclusions In summary, the development of NMRG signature provided a more comprehensive understanding of mitochondrial dysfunction in HCC, helped predict prognosis and tumor microenvironment, and provided potential targeted therapies for HCC patients with different NMRG prognosis scores.
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Kušíková K, Feichtinger RG, Csillag B, Kalev OK, Weis S, Duba HC, Mayr JA, Weis D. Case Report and Review of the Literature: A New and a Recurrent Variant in the VARS2 Gene Are Associated With Isolated Lethal Hypertrophic Cardiomyopathy, Hyperlactatemia, and Pulmonary Hypertension in Early Infancy. Front Pediatr 2021; 9:660076. [PMID: 33937156 PMCID: PMC8085550 DOI: 10.3389/fped.2021.660076] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Accepted: 03/22/2021] [Indexed: 01/01/2023] Open
Abstract
Mitochondriopathies represent a wide spectrum of miscellaneous disorders with multisystem involvement, which are caused by various genetic changes. The establishment of the diagnosis of mitochondriopathy is often challenging. Recently, several mutations of the VARS2 gene encoding the mitochondrial valyl-tRNA synthetase were associated with early onset encephalomyopathies or encephalocardiomyopathies with major clinical features such as hypotonia, developmental delay, brain MRI changes, epilepsy, hypertrophic cardiomyopathy, and plasma lactate elevation. However, the correlation between genotype and phenotype still remains unclear. In this paper we present a male Caucasian patient with a recurrent c.1168G>A (p.Ala390Thr) and a new missense biallelic variant c.2758T>C (p.Tyr920His) in the VARS2 gene which were detected by whole exome sequencing (WES). VARS2 protein was reduced in the patient's muscle. A resulting defect of oxidative phosphorylation (OXPHOS) was proven by enzymatic assay, western blotting and immunohistochemistry from a homogenate of skeletal muscle tissue. Clinical signs of our patient included hyperlactatemia, hypertrophic cardiomyopathy (HCM) and pulmonary hypertension, which led to early death at the age of 47 days without any other known accompanying signs. The finding of novel variants in the VARS2 gene expands the spectrum of known mutations and phenotype presentation. Based on our findings we recommend to consider possible mitochondriopathy and to include the analysis of the VARS2 gene in the genetic diagnostic algorithm in cases with early manifesting and rapidly progressing HCM with hyperlactatemia.
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Affiliation(s)
- Katarína Kušíková
- Department of Pediatric Neurology, Medical School, Comenius University and National Institute of Children's Diseases, Bratislava, Slovakia
| | - René Günther Feichtinger
- Department of Pediatrics, University Hospital Salzburg, Paracelsus Medical University Salzburg, Salzburg, Austria
| | - Bernhard Csillag
- Department of Neonatology, Kepler University Hospital Med Campus IV, Johannes Kepler University Linz, Linz, Austria
| | - Ognian Kostadinov Kalev
- Division of Neuropathology, Department of Pathology and Molecular Pathology, Kepler University Hospital Neuromed Campus, Johannes Kepler University Linz, Linz, Austria
| | - Serge Weis
- Division of Neuropathology, Department of Pathology and Molecular Pathology, Kepler University Hospital Neuromed Campus, Johannes Kepler University Linz, Linz, Austria
| | - Hans-Christoph Duba
- Department of Medical Genetics, Kepler University Hospital Med Campus IV, Johannes Kepler University Linz, Linz, Austria
| | - Johannes Adalbert Mayr
- Department of Pediatrics, University Hospital Salzburg, Paracelsus Medical University Salzburg, Salzburg, Austria
| | - Denisa Weis
- Department of Medical Genetics, Kepler University Hospital Med Campus IV, Johannes Kepler University Linz, Linz, Austria
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Ruzman L, Kolic I, Radic Nisevic J, Ruzic Barsic A, Skarpa Prpic I, Prpic I. A novel VARS2 gene variant in a patient with epileptic encephalopathy. Ups J Med Sci 2019; 124:273-277. [PMID: 31623496 PMCID: PMC6968568 DOI: 10.1080/03009734.2019.1670297] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Background: Mitochondrial disorders are heterogeneous clinical syndromes caused by defective activity in the mitochondrial respiratory chain, resulting in a faulty oxidative phosphorylation system. These inherited disorders are individually rare, and furthermore they are phenotypic variables. The genetically characterized mitochondrial disorders are rarely associated with epileptic encephalopathies.Case presentation: We present the clinical phenotype, biochemical analysis, and electrographic and neuro-radiological features of a 5-month-old girl with epileptic encephalopathy, microcephaly, severe psychomotor delay, hypertrophic cardiomyopathy, and abnormal MRI scan. Using whole-genome sequencing technique, compound heterozygous mutations of the VARS2 gene were revealed, with one previously unreported frameshift mutation.Conclusion: Our report extends the phenotypic spectrum of VARS2-related disorders with an initial presentation of epileptic encephalopathy and early death due to malignant arrhythmia.
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Affiliation(s)
- Lucija Ruzman
- Child Neurology and Child Psychiatry Department, Pediatric Clinic, Clinical Hospital Center Rijeka, Rijeka, Croatia
| | - Ivana Kolic
- Child Neurology and Child Psychiatry Department, Pediatric Clinic, Clinical Hospital Center Rijeka, Rijeka, Croatia
| | - Jelena Radic Nisevic
- Child Neurology and Child Psychiatry Department, Pediatric Clinic, Clinical Hospital Center Rijeka, Rijeka, Croatia
- University of Rijeka, School of Medicine Rijeka, Rijeka, Croatia
| | | | | | - Igor Prpic
- Child Neurology and Child Psychiatry Department, Pediatric Clinic, Clinical Hospital Center Rijeka, Rijeka, Croatia
- University of Rijeka, School of Medicine Rijeka, Rijeka, Croatia
- CONTACT Igor Prpic Child Neurology and Child Psychiatry Department, Pediatric Clinic, Clinical Hospital Center Rijeka, Istarska 43, 51000 Rijeka, Croatia
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Chin HL, Goh DLM, Wang FS, Tay SKH, Heng CK, Donnini C, Baruffini E, Pines O. A combination of two novel VARS2 variants causes a mitochondrial disorder associated with failure to thrive and pulmonary hypertension. J Mol Med (Berl) 2019; 97:1557-1566. [PMID: 31529142 DOI: 10.1007/s00109-019-01834-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2019] [Revised: 07/29/2019] [Accepted: 08/13/2019] [Indexed: 01/30/2023]
Abstract
The VARS2 gene encodes a mitochondrial valyl-transfer RNA synthetase which is used in mitochondrial translation. To date, several patients with VARS2 pathogenic variants have been described in the literature. These patients have features of lactic acidosis with encephalomyopathy. We present a case of an infant with lactic acidosis, failure to thrive, and severe primary pulmonary hypertension who was found to be a compound heterozygote for two novel VARS2 variants (c.1940C>T, p.(Thr647Met) and c.2318G>A, p.(Arg773Gln)). The patient was treated with vitamin supplements and a carbohydrate-restricted diet. The lactic acidosis and failure to thrive resolved, and he showed good growth and development. Functional studies and molecular analysis employed a yeast model system and the VAS1 gene (yeast homolog of VARS2). VAS1 genes harboring either one of two mutations corresponding to the two novel variants in the VARS2 gene, exhibited partially reduced function in haploid yeast strains. A combination of both VAS1 variant alleles in a diploid yeast cell exhibited a more significant decrease in oxidative metabolism-dependent growth and in the oxygen consumption rate (reminiscent of the patient who carries two mutant VARS2 alleles). Our results demonstrate the pathogenicity of the biallellic novel VARS2 variants. KEY MESSAGES: • A case of an infant who is a compound heterozygote for two novel VARS2 variants. • This infant displayed lactic acidosis, failure to thrive, and pulmonary hypertension. • Treatment of the patient with a carbohydrate-restricted diet resulted in good growth and development. • Studies with the homologous yeast VAS1 gene showed reduced function of corresponding single mutant in haploid yeast strains. • A combination of both VAS1 variant alleles in diploid yeast exhibited a more significant decrease in function, thereby confirming the pathogenicity of the biallellic novel VARS2 variants.
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Affiliation(s)
- Hui-Lin Chin
- Khoo Teck Puat-National University Children's Medical Institute, National University Health Systems (NUHS), Singapore, Singapore. .,Department of Pediatrics, Yong Loo Lin School of Medicine, National University Hospital, National University of Singapore, 5 Lower Kent Ridge Road, Singapore, 119074, Singapore.
| | - Denise Li-Meng Goh
- Khoo Teck Puat-National University Children's Medical Institute, National University Health Systems (NUHS), Singapore, Singapore.,Department of Pediatrics, Yong Loo Lin School of Medicine, National University Hospital, National University of Singapore, 5 Lower Kent Ridge Road, Singapore, 119074, Singapore
| | - Furene Sijia Wang
- Khoo Teck Puat-National University Children's Medical Institute, National University Health Systems (NUHS), Singapore, Singapore.,Department of Pediatrics, Yong Loo Lin School of Medicine, National University Hospital, National University of Singapore, 5 Lower Kent Ridge Road, Singapore, 119074, Singapore
| | - Stacey Kiat Hong Tay
- Khoo Teck Puat-National University Children's Medical Institute, National University Health Systems (NUHS), Singapore, Singapore.,Department of Pediatrics, Yong Loo Lin School of Medicine, National University Hospital, National University of Singapore, 5 Lower Kent Ridge Road, Singapore, 119074, Singapore
| | - Chew Kiat Heng
- Khoo Teck Puat-National University Children's Medical Institute, National University Health Systems (NUHS), Singapore, Singapore.,Department of Pediatrics, Yong Loo Lin School of Medicine, National University Hospital, National University of Singapore, 5 Lower Kent Ridge Road, Singapore, 119074, Singapore
| | - Claudia Donnini
- Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma, Parco Area delle Scienze 11/A, 43124, Parma, Italy
| | - Enrico Baruffini
- Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma, Parco Area delle Scienze 11/A, 43124, Parma, Italy.
| | - Ophry Pines
- Department of Microbiology and Molecular Genetics, IMRIC, Faculty of Medicine, Hebrew University of Jerusalem, Jerusalem, Israel.,NUS-HUJ-CREATE Program and the Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
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11
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Abu Diab A, AlTalbishi A, Rosin B, Kanaan M, Kamal L, Swaroop A, Chowers I, Banin E, Sharon D, Khateb S. The combination of whole-exome sequencing and clinical analysis allows better diagnosis of rare syndromic retinal dystrophies. Acta Ophthalmol 2019; 97:e877-e886. [PMID: 30925032 PMCID: PMC11377105 DOI: 10.1111/aos.14095] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Accepted: 03/03/2019] [Indexed: 01/05/2023]
Abstract
PURPOSE To identify the accurate clinical diagnosis of rare syndromic inherited retinal diseases (IRDs) based on the combination of clinical and genetic analyses. METHODS Four unrelated families with various autosomal recessive syndromic inherited retinal diseases were genetically investigated using whole-exome sequencing (WES). RESULTS Two affected subjects in family MOL0760 presented with a distinctive combination of short stature, developmental delay, congenital mental retardation, microcephaly, facial dysmorphism and retinitis pigmentosa (RP). Subjects were clinically diagnosed with suspected Kabuki syndrome. WES revealed a homozygous nonsense mutation (c.5492dup, p.Asn1831Lysfs*8) in VPS13B that is known to cause Cohen syndrome. The index case of family MOL1514 presented with both RP and liver dysfunction, suspected initially to be related. WES identified a homozygous frameshift mutation (c.1787_1788del, p.His596Argfs*47) in AGBL5, associated with nonsyndromic RP. The MOL1592 family included three affected subjects with crystalline retinopathy, skin ichthyosis, short stature and congenital adrenal hypoplasia, and were found to harbour a homozygous nonsense mutation (c.682C>T, p.Arg228Cys) in ALDH3A2, reported to cause Sjögren-Larsson syndrome (SLS). In the fourth family, SJ002, two siblings presented with hypotony, psychomotor delay, dysmorphic facial features, pathologic myopia, progressive external ophthalmoplegia and diffuse retinal atrophy. Probands were suspected to have atypical Kearns-Sayre syndrome, but were diagnosed with combined oxidative phosphorylation deficiency-20 due to a novel suspected missense variant (c.1691C>T, p.Ala564Val) in VARS2. CONCLUSION Our findings emphasize the important complement of WES and thorough clinical investigation in establishing precise clinical diagnosis. This approach constitutes the basis for personalized medicine in rare IRDs.
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Affiliation(s)
- Alaa Abu Diab
- Department of Ophthalmology, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
| | | | - Boris Rosin
- Department of Ophthalmology, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
| | - Moien Kanaan
- Hereditary Research Lab, Bethlehem University, Jerusalem, Israel
| | - Lara Kamal
- Hereditary Research Lab, Bethlehem University, Jerusalem, Israel
| | - Anand Swaroop
- Neurobiology-Neurodegeneration & Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Itay Chowers
- Department of Ophthalmology, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
| | - Eyal Banin
- Department of Ophthalmology, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
| | - Dror Sharon
- Department of Ophthalmology, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
| | - Samer Khateb
- Department of Ophthalmology, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
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12
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Begliuomini C, Magli G, Di Rocco M, Santorelli FM, Cassandrini D, Nesti C, Deodato F, Diodato D, Casellato S, Simula DM, Dessì V, Eusebi A, Carta A, Sotgiu S. VARS2-linked mitochondrial encephalopathy: two case reports enlarging the clinical phenotype. BMC MEDICAL GENETICS 2019; 20:77. [PMID: 31064326 PMCID: PMC6505124 DOI: 10.1186/s12881-019-0798-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/17/2018] [Accepted: 04/03/2019] [Indexed: 12/19/2022]
Abstract
Background Mitochondrial respiratory chain consists of five complexes encoded by nuclear and mitochondrial genomes. Mitochondrial aminoacyl-tRNA synthetases are key enzymes in the synthesis of such complexes. Bi-allelic variants of VARS2, a nuclear gene encoding for valyl-tRNA (Val-tRNA) synthetase, are associated to several forms of mitochondrial encephalopathies or cardiomyoencephalopathies. Among these, the rare homozygous c.1100C > T (p.Thr367Ile) mutation variably presents with progressive developmental delay, axial hypotonia, limbs spasticity, drug-resistant epilepsy leading, in some cases, to premature death. Yet only six cases, of which three are siblings, harbouring this homozygous mutation have been described worldwide. Case presentation Hereby, we report two additional cases of two non-related young girls from Sardinia, born from non-consanguineous and healthy parents, carrying the aforesaid homozygous VARS2 variant. At onset both the patients presented with worsening psychomotor delay, muscle hypotonia and brisk tendon reflexes. Standard genetic tests were normal, as well as metabolic investigations. Brain MRI showed unspecific progressive abnormalities, such as corpus callosum hypoplasia (patient A) and cerebellar atrophy (patient A and B). Diagnosis was reached by adopting massive parallel next generation sequencing. Notably clinical phenotype of the first patient appears to be milder compared to previous known cases. The second patient eventually developed refractory epilepsy and currently presents with severe global impairment. Because no specific treatment is available as yet, both patients are treated with supporting antioxidant compounds along with symptomatic therapies. Conclusions Given the paucity of clinical data about this very rare mitochondrial encephalopathy, our report might contribute to broaden the phenotypic spectrum of the disorder. Moreover, noteworthy, three out of five pedigrees so far described belong to the Northern Sardinia ethnicity.
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Affiliation(s)
- Chiara Begliuomini
- Unit of Child Neuropsychiatry Residency Program, University Hospital of Sassari, Viale San Pietro 43/B, I-07100, Sassari, Italy.
| | - Giorgio Magli
- Unit of Child Neuropsychiatry Residency Program, University Hospital of Sassari, Viale San Pietro 43/B, I-07100, Sassari, Italy
| | - Maja Di Rocco
- Department of Pediatrics, Unit of Rare Diseases, Giannina Gaslini Institute, Via Gerolamo Gaslini, 5, 16147, Genoa, Italy
| | - Filippo M Santorelli
- Molecular Medicine for Neurodegenerative and Neuromuscular Diseases Unit, IRCCS Fondazione Stella Maris, Viale del Tirreno, 331 56018 Calambrone, Pisa, Italy
| | - Denise Cassandrini
- Molecular Medicine for Neurodegenerative and Neuromuscular Diseases Unit, IRCCS Fondazione Stella Maris, Viale del Tirreno, 331 56018 Calambrone, Pisa, Italy
| | - Claudia Nesti
- Molecular Medicine for Neurodegenerative and Neuromuscular Diseases Unit, IRCCS Fondazione Stella Maris, Viale del Tirreno, 331 56018 Calambrone, Pisa, Italy
| | - Federica Deodato
- Metabolic Division, 'Bambino Gesu' Children's Research Hospital, Piazza di Sant'Onofrio4, 00165, Rome, Italy
| | - Daria Diodato
- Unit of Neuromuscular and Neurodegenerative Disorders, Laboratory of Molecular Medicine, 'Bambino Gesu' Children's Research Hospital, Piazza di Sant'Onofrio, 4, 00165, Rome, Italy
| | - Susanna Casellato
- Unit of Child Neuropsychiatry Residency Program, University Hospital of Sassari, Viale San Pietro 43/B, I-07100, Sassari, Italy
| | - Delia M Simula
- Unit of Child Neuropsychiatry Residency Program, University Hospital of Sassari, Viale San Pietro 43/B, I-07100, Sassari, Italy
| | - Veronica Dessì
- Unit of Child Neuropsychiatry Residency Program, University Hospital of Sassari, Viale San Pietro 43/B, I-07100, Sassari, Italy
| | - Anna Eusebi
- Unit of Child Neuropsychiatry Residency Program, University Hospital of Sassari, Viale San Pietro 43/B, I-07100, Sassari, Italy
| | - Alessandra Carta
- Unit of Child Neuropsychiatry Residency Program, University Hospital of Sassari, Viale San Pietro 43/B, I-07100, Sassari, Italy.,Child Psychiatry Unit, Department of Neuroscience, 'Bambino Gesù' Children's Research Hospital, Piazza di Sant'Onofrio, 4, 00165, Rome, Italy
| | - Stefano Sotgiu
- Unit of Child Neuropsychiatry Residency Program, University Hospital of Sassari, Viale San Pietro 43/B, I-07100, Sassari, Italy
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13
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González-Serrano LE, Chihade JW, Sissler M. When a common biological role does not imply common disease outcomes: Disparate pathology linked to human mitochondrial aminoacyl-tRNA synthetases. J Biol Chem 2019; 294:5309-5320. [PMID: 30647134 PMCID: PMC6462531 DOI: 10.1074/jbc.rev118.002953] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Mitochondrial aminoacyl-tRNA synthetases (mt-aaRSs) are essential components of the mitochondrial translation machinery. The correlation of mitochondrial disorders with mutations in these enzymes has raised the interest of the scientific community over the past several years. Most surprising has been the wide-ranging presentation of clinical manifestations in patients with mt-aaRS mutations, despite the enzymes' common biochemical role. Even among cases where a common physiological system is affected, phenotypes, severity, and age of onset varies depending on which mt-aaRS is mutated. Here, we review work done thus far and propose a categorization of diseases based on tissue specificity that highlights emerging patterns. We further discuss multiple in vitro and in cellulo efforts to characterize the behavior of WT and mutant mt-aaRSs that have shaped hypotheses about the molecular causes of these pathologies. Much remains to do in order to complete our understanding of these proteins. We expect that futher work is likely to result in the discovery of new roles for the mt-aaRSs in addition to their fundamental function in mitochondrial translation, informing the development of treatment strategies and diagnoses.
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Affiliation(s)
- Ligia Elena González-Serrano
- From the Université de Strasbourg, CNRS, Architecture et Réactivité de l'ARN, UPR9002, F-67000 Strasbourg, France and
| | - Joseph W Chihade
- the Department of Chemistry, Carleton College, Northfield, Minnesota 55057
| | - Marie Sissler
- From the Université de Strasbourg, CNRS, Architecture et Réactivité de l'ARN, UPR9002, F-67000 Strasbourg, France and
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14
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Kuo ME, Theil AF, Kievit A, Malicdan MC, Introne WJ, Christian T, Verheijen FW, Smith DEC, Mendes MI, Hussaarts-Odijk L, van der Meijden E, van Slegtenhorst M, Wilke M, Vermeulen W, Raams A, Groden C, Shimada S, Meyer-Schuman R, Hou YM, Gahl WA, Antonellis A, Salomons GS, Mancini GMS. Cysteinyl-tRNA Synthetase Mutations Cause a Multi-System, Recessive Disease That Includes Microcephaly, Developmental Delay, and Brittle Hair and Nails. Am J Hum Genet 2019; 104:520-529. [PMID: 30824121 DOI: 10.1016/j.ajhg.2019.01.006] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2018] [Accepted: 01/15/2019] [Indexed: 02/06/2023] Open
Abstract
Aminoacyl-tRNA synthetases (ARSs) are essential enzymes responsible for charging tRNA molecules with cognate amino acids. Consistent with the essential function and ubiquitous expression of ARSs, mutations in 32 of the 37 ARS-encoding loci cause severe, early-onset recessive phenotypes. Previous genetic and functional data suggest a loss-of-function mechanism; however, our understanding of the allelic and locus heterogeneity of ARS-related disease is incomplete. Cysteinyl-tRNA synthetase (CARS) encodes the enzyme that charges tRNACys with cysteine in the cytoplasm. To date, CARS variants have not been implicated in any human disease phenotype. Here, we report on four subjects from three families with complex syndromes that include microcephaly, developmental delay, and brittle hair and nails. Each affected person carries bi-allelic CARS variants: one individual is compound heterozygous for c.1138C>T (p.Gln380∗) and c.1022G>A (p.Arg341His), two related individuals are compound heterozygous for c.1076C>T (p.Ser359Leu) and c.1199T>A (p.Leu400Gln), and one individual is homozygous for c.2061dup (p.Ser688Glnfs∗2). Measurement of protein abundance, yeast complementation assays, and assessments of tRNA charging indicate that each CARS variant causes a loss-of-function effect. Compared to subjects with previously reported ARS-related diseases, individuals with bi-allelic CARS variants are unique in presenting with a brittle-hair-and-nail phenotype, which most likely reflects the high cysteine content in human keratins. In sum, our efforts implicate CARS variants in human inherited disease, expand the locus and clinical heterogeneity of ARS-related clinical phenotypes, and further support impaired tRNA charging as the primary mechanism of recessive ARS-related disease.
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Affiliation(s)
- Molly E Kuo
- Cellular and Molecular Biology Program, University of Michigan Medical School, Ann Arbor, MI 48109, USA; Medical Scientist Training Program, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Arjan F Theil
- Department of Molecular Genetics, Oncode Institute, Erasmus Medical Center, University Medical Center Rotterdam, Dr. Molewaterplein 40, 3015 CN Rotterdam, the Netherlands
| | - Anneke Kievit
- Department of Clinical Genetics, Erasmus Medical Center, University Medical Center, 3015 GD Rotterdam, the Netherlands
| | - May Christine Malicdan
- Undiagnosed Diseases Program and Office of the Clinical Director, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Wendy J Introne
- Undiagnosed Diseases Program and Office of the Clinical Director, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Thomas Christian
- Department of Biochemistry and Molecular Biochemistry, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Frans W Verheijen
- Department of Clinical Genetics, Erasmus Medical Center, University Medical Center, 3015 GD Rotterdam, the Netherlands
| | - Desiree E C Smith
- Metabolic Unit, Department of Clinical Chemistry, Amsterdam University Medical Center and Amsterdam Gastroenterology and Metabolism, Vrije Universiteit Amsterdam, Amsterdam Neuroscience, 1081 HZ Amsterdam, the Netherlands
| | - Marisa I Mendes
- Metabolic Unit, Department of Clinical Chemistry, Amsterdam University Medical Center and Amsterdam Gastroenterology and Metabolism, Vrije Universiteit Amsterdam, Amsterdam Neuroscience, 1081 HZ Amsterdam, the Netherlands
| | - Lidia Hussaarts-Odijk
- Department of Clinical Genetics, Erasmus Medical Center, University Medical Center, 3015 GD Rotterdam, the Netherlands
| | - Eric van der Meijden
- Department of Clinical Genetics, Erasmus Medical Center, University Medical Center, 3015 GD Rotterdam, the Netherlands
| | - Marjon van Slegtenhorst
- Department of Clinical Genetics, Erasmus Medical Center, University Medical Center, 3015 GD Rotterdam, the Netherlands
| | - Martina Wilke
- Department of Clinical Genetics, Erasmus Medical Center, University Medical Center, 3015 GD Rotterdam, the Netherlands
| | - Wim Vermeulen
- Department of Molecular Genetics, Oncode Institute, Erasmus Medical Center, University Medical Center Rotterdam, Dr. Molewaterplein 40, 3015 CN Rotterdam, the Netherlands
| | - Anja Raams
- Department of Molecular Genetics, Oncode Institute, Erasmus Medical Center, University Medical Center Rotterdam, Dr. Molewaterplein 40, 3015 CN Rotterdam, the Netherlands
| | - Catherine Groden
- Undiagnosed Diseases Program and Office of the Clinical Director, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Shino Shimada
- Undiagnosed Diseases Program and Office of the Clinical Director, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Rebecca Meyer-Schuman
- Department of Human Genetics, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Ya Ming Hou
- Department of Biochemistry and Molecular Biochemistry, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - William A Gahl
- Undiagnosed Diseases Program and Office of the Clinical Director, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Anthony Antonellis
- Cellular and Molecular Biology Program, University of Michigan Medical School, Ann Arbor, MI 48109, USA; Department of Human Genetics, University of Michigan Medical School, Ann Arbor, MI 48109, USA; Department of Neurology, University of Michigan Medical School, Ann Arbor, MI 48109, USA.
| | - Gajja S Salomons
- Metabolic Unit, Department of Clinical Chemistry, Amsterdam University Medical Center and Amsterdam Gastroenterology and Metabolism, Vrije Universiteit Amsterdam, Amsterdam Neuroscience, 1081 HZ Amsterdam, the Netherlands; Genetic Metabolic Diseases, Amsterdam University Medical Center, University of Amsterdam, 1081 HZ Amsterdam, the Netherlands.
| | - Grazia M S Mancini
- Department of Clinical Genetics, Erasmus Medical Center, University Medical Center, 3015 GD Rotterdam, the Netherlands
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15
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Friedman J, Smith DE, Issa MY, Stanley V, Wang R, Mendes MI, Wright MS, Wigby K, Hildreth A, Crawford JR, Koehler AE, Chowdhury S, Nahas S, Zhai L, Xu Z, Lo WS, James KN, Musaev D, Accogli A, Guerrero K, Tran LT, Omar TEI, Ben-Omran T, Dimmock D, Kingsmore SF, Salomons GS, Zaki MS, Bernard G, Gleeson JG. Biallelic mutations in valyl-tRNA synthetase gene VARS are associated with a progressive neurodevelopmental epileptic encephalopathy. Nat Commun 2019; 10:707. [PMID: 30755602 PMCID: PMC6372641 DOI: 10.1038/s41467-018-07067-3] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2018] [Accepted: 10/03/2018] [Indexed: 12/27/2022] Open
Abstract
Aminoacyl-tRNA synthetases (ARSs) function to transfer amino acids to cognate tRNA molecules, which are required for protein translation. To date, biallelic mutations in 31 ARS genes are known to cause recessive, early-onset severe multi-organ diseases. VARS encodes the only known valine cytoplasmic-localized aminoacyl-tRNA synthetase. Here, we report seven patients from five unrelated families with five different biallelic missense variants in VARS. Subjects present with a range of global developmental delay, epileptic encephalopathy and primary or progressive microcephaly. Longitudinal assessment demonstrates progressive cortical atrophy and white matter volume loss. Variants map to the VARS tRNA binding domain and adjacent to the anticodon domain, and disrupt highly conserved residues. Patient primary cells show intact VARS protein but reduced enzymatic activity, suggesting partial loss of function. The implication of VARS in pediatric neurodegeneration broadens the spectrum of human diseases due to mutations in tRNA synthetase genes.
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Affiliation(s)
- Jennifer Friedman
- Department of Neurosciences, University of California San Diego, La Jolla, CA, 92093, USA
- Division of Child Neurology, Rady Children's Hospital, San Diego, CA, 92123, USA
- Department of Pediatrics, University of California San Diego, La Jolla, CA, 92093, USA
- Rady Children's Institute for Genomic Medicine, Rady Children's Hospital, San Diego, CA, 92123, USA
| | - Desiree E Smith
- Department of Clinical Chemistry, Metabolic Unit, Amsterdam UMC (University Medical Centers), Vrije Universiteit Amsterdam, 1081 HV, Amsterdam, The Netherlands
- Gastroenterology & Metabolism Amsterdam Neuroscience, 1081 HV, Amsterdam, The Netherlands
| | - Mahmoud Y Issa
- Department of Clinical Genetics, National Research Centre, Cairo, 12311, Egypt
| | - Valentina Stanley
- Department of Neurosciences, University of California San Diego, La Jolla, CA, 92093, USA
- Department of Neurosciences, Howard Hughes Medical Institute, University of California, San Diego, La Jolla, CA, 92093, USA
| | - Rengang Wang
- Department of Neurosciences, University of California San Diego, La Jolla, CA, 92093, USA
- Department of Neurosciences, Howard Hughes Medical Institute, University of California, San Diego, La Jolla, CA, 92093, USA
| | - Marisa I Mendes
- Department of Clinical Chemistry, Metabolic Unit, Amsterdam UMC (University Medical Centers), Vrije Universiteit Amsterdam, 1081 HV, Amsterdam, The Netherlands
- Gastroenterology & Metabolism Amsterdam Neuroscience, 1081 HV, Amsterdam, The Netherlands
| | - Meredith S Wright
- Rady Children's Institute for Genomic Medicine, Rady Children's Hospital, San Diego, CA, 92123, USA
| | - Kristen Wigby
- Department of Pediatrics, University of California San Diego, La Jolla, CA, 92093, USA
- Rady Children's Institute for Genomic Medicine, Rady Children's Hospital, San Diego, CA, 92123, USA
| | - Amber Hildreth
- Department of Pediatrics, University of California San Diego, La Jolla, CA, 92093, USA
- Rady Children's Institute for Genomic Medicine, Rady Children's Hospital, San Diego, CA, 92123, USA
| | - John R Crawford
- Department of Neurosciences, University of California San Diego, La Jolla, CA, 92093, USA
- Division of Child Neurology, Rady Children's Hospital, San Diego, CA, 92123, USA
- Department of Pediatrics, University of California San Diego, La Jolla, CA, 92093, USA
| | - Alanna E Koehler
- Department of Neurosciences, Howard Hughes Medical Institute, University of California, San Diego, La Jolla, CA, 92093, USA
| | - Shimul Chowdhury
- Rady Children's Institute for Genomic Medicine, Rady Children's Hospital, San Diego, CA, 92123, USA
| | - Shareef Nahas
- Rady Children's Institute for Genomic Medicine, Rady Children's Hospital, San Diego, CA, 92123, USA
| | - Liting Zhai
- IAS HKUST-Scripps R&D Laboratory, Institute for Advanced Study, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Zhiwen Xu
- IAS HKUST-Scripps R&D Laboratory, Institute for Advanced Study, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
- Pangu Biopharma, Edinburgh Tower, The Landmark, 15 Queen's Road Central, Hong Kong, China
| | - Wing-Sze Lo
- IAS HKUST-Scripps R&D Laboratory, Institute for Advanced Study, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
- Pangu Biopharma, Edinburgh Tower, The Landmark, 15 Queen's Road Central, Hong Kong, China
| | - Kiely N James
- Department of Neurosciences, University of California San Diego, La Jolla, CA, 92093, USA
- Department of Neurosciences, Howard Hughes Medical Institute, University of California, San Diego, La Jolla, CA, 92093, USA
| | - Damir Musaev
- Department of Neurosciences, University of California San Diego, La Jolla, CA, 92093, USA
- Department of Neurosciences, Howard Hughes Medical Institute, University of California, San Diego, La Jolla, CA, 92093, USA
| | - Andrea Accogli
- Departments of Neurology and Neurosurgery, Pediatrics and Human Genetics, McGill University, Montreal, H3A 0G4, Canada
- IRCCS Istituto Giannina Gaslini, Genova, 16147, Italy
| | - Kether Guerrero
- Departments of Neurology and Neurosurgery, Pediatrics and Human Genetics, McGill University, Montreal, H3A 0G4, Canada
- Division of Medical Genetics, Montreal Children's Hospital, McGill University Health Center, Montreal, H4A 3J1, Canada
- Child Health and Human Development Program, Research Institute of the McGill University Health Center, Montreal, H4A 3J1, Canada
| | - Luan T Tran
- Departments of Neurology and Neurosurgery, Pediatrics and Human Genetics, McGill University, Montreal, H3A 0G4, Canada
- Division of Medical Genetics, Montreal Children's Hospital, McGill University Health Center, Montreal, H4A 3J1, Canada
- Child Health and Human Development Program, Research Institute of the McGill University Health Center, Montreal, H4A 3J1, Canada
| | - Tarek E I Omar
- Department of Pediatrics, Alexandria University, Alexandria, 21526, Egypt
| | - Tawfeg Ben-Omran
- Clinical and Metabolic Genetics, Department of Pediatrics, Hamad Medical Corporation, 3050, Doha, Qatar
| | - David Dimmock
- Rady Children's Institute for Genomic Medicine, Rady Children's Hospital, San Diego, CA, 92123, USA
| | - Stephen F Kingsmore
- Rady Children's Institute for Genomic Medicine, Rady Children's Hospital, San Diego, CA, 92123, USA
| | - Gajja S Salomons
- Department of Clinical Chemistry, Metabolic Unit, Amsterdam UMC (University Medical Centers), Vrije Universiteit Amsterdam, 1081 HV, Amsterdam, The Netherlands
- Gastroenterology & Metabolism Amsterdam Neuroscience, 1081 HV, Amsterdam, The Netherlands
| | - Maha S Zaki
- Department of Clinical Genetics, National Research Centre, Cairo, 12311, Egypt
| | - Geneviève Bernard
- Departments of Neurology and Neurosurgery, Pediatrics and Human Genetics, McGill University, Montreal, H3A 0G4, Canada
- Division of Medical Genetics, Montreal Children's Hospital, McGill University Health Center, Montreal, H4A 3J1, Canada
- Child Health and Human Development Program, Research Institute of the McGill University Health Center, Montreal, H4A 3J1, Canada
| | - Joseph G Gleeson
- Department of Neurosciences, University of California San Diego, La Jolla, CA, 92093, USA.
- Division of Child Neurology, Rady Children's Hospital, San Diego, CA, 92123, USA.
- Department of Pediatrics, University of California San Diego, La Jolla, CA, 92093, USA.
- Rady Children's Institute for Genomic Medicine, Rady Children's Hospital, San Diego, CA, 92123, USA.
- Department of Neurosciences, Howard Hughes Medical Institute, University of California, San Diego, La Jolla, CA, 92093, USA.
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16
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Ma K, Xie M, He X, Liu G, Lu X, Peng Q, Zhong B, Li N. A novel compound heterozygous mutation in VARS2 in a newborn with mitochondrial cardiomyopathy: a case report of a Chinese family. BMC MEDICAL GENETICS 2018; 19:202. [PMID: 30458719 PMCID: PMC6247698 DOI: 10.1186/s12881-018-0689-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/11/2018] [Accepted: 09/20/2018] [Indexed: 12/20/2022]
Abstract
Background Genetic defects in the mitochondrial aminoacyl-tRNA synthetase are important causes of mitochondrial disorders. VARS2 is one of the genes encoding aminoacyl-tRNA synthetases. Recently, an increasing number of pathogenic variants of VARS2 have been reported. Case presentation We report the novel compound heterozygous pathogenic VARS2 mutations c.643 C > T (p. His215Tyr) and c.1354 A > G (p. Met452Val) in a female infant who presented with poor sucking at birth, poor activity, hyporeflexia, hypertonia, persistent pulmonary hypertension of newborn (PPHN), metabolic acidosis, severe lactic acidosis, expansion and hypertrophic cardiomyopathy. These heterozygous mutations were carried individually by the proband’s parents and elder sister; the two mutations segregated in the family and were the cause of the disease in the proband.The c.643 C > T (p. His215Tyr) mutation was not described in the ExaC, GNomAD and 1000 Genomes Project databases, and the frequency of c.1354 A > G (p. Met452Val) was < 0.001 in these gene databases.The two mutated amino acids were located in a highly conserved region of the VARS2 protein that is important for its interaction with the cognate tRNA. The two missense mutations were predicted by online tools to be damaging and deleterious. Conclusions Our report expands the spectrum of known pathogenicVARS2 variants associated with mitochondrial disorders in humans.VARS2 deficiency may cause a severe neonatal presentation with structural cardiac abnormalities.
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Affiliation(s)
- Keze Ma
- Department of Neonatal Intensive Care Unit, Dongguan Children's Hospital, Dongguan, 523325, Guangdong, China.,Department of Medical and Molecular Genetics, Dongguan Institute of Pediatrics, Dongguan, 523325, Guangdong, China
| | - Mingyu Xie
- Department of Neonatal Intensive Care Unit, Dongguan Children's Hospital, Dongguan, 523325, Guangdong, China.,Department of Medical and Molecular Genetics, Dongguan Institute of Pediatrics, Dongguan, 523325, Guangdong, China
| | - Xiaoguang He
- Department of Neonatal Intensive Care Unit, Dongguan Children's Hospital, Dongguan, 523325, Guangdong, China.,Department of Medical and Molecular Genetics, Dongguan Institute of Pediatrics, Dongguan, 523325, Guangdong, China
| | - Guojun Liu
- Department of Neonatal Intensive Care Unit, Dongguan Children's Hospital, Dongguan, 523325, Guangdong, China.,Department of Medical and Molecular Genetics, Dongguan Institute of Pediatrics, Dongguan, 523325, Guangdong, China
| | - Xiaomei Lu
- Department of Medical and Molecular Genetics, Dongguan Institute of Pediatrics, Dongguan, 523325, Guangdong, China
| | - Qi Peng
- Department of Medical and Molecular Genetics, Dongguan Institute of Pediatrics, Dongguan, 523325, Guangdong, China
| | - Baimao Zhong
- Department of Neonatal Intensive Care Unit, Dongguan Children's Hospital, Dongguan, 523325, Guangdong, China. .,Department of Medical and Molecular Genetics, Dongguan Institute of Pediatrics, Dongguan, 523325, Guangdong, China.
| | - Ning Li
- Department of Neonatal Intensive Care Unit, Dongguan Children's Hospital, Dongguan, 523325, Guangdong, China. .,Department of Medical and Molecular Genetics, Dongguan Institute of Pediatrics, Dongguan, 523325, Guangdong, China.
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17
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Mitochondrial DNA transcription and translation: clinical syndromes. Essays Biochem 2018; 62:321-340. [PMID: 29980628 PMCID: PMC6056718 DOI: 10.1042/ebc20170103] [Citation(s) in RCA: 61] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Revised: 05/17/2018] [Accepted: 05/21/2018] [Indexed: 01/15/2023]
Abstract
Diagnosing primary mitochondrial diseases is challenging in clinical practice. Although, defective oxidative phosphorylation (OXPHOS) is the common final pathway, it is unknown why different mtDNA or nuclear mutations result in largely heterogeneous and often tissue -specific clinical presentations. Mitochondrial tRNA (mt-tRNA) mutations are frequent causes of mitochondrial diseases both in children and adults. However numerous nuclear mutations involved in mitochondrial protein synthesis affecting ubiquitously expressed genes have been reported in association with very tissue specific clinical manifestations suggesting that there are so far unknown factors determining the tissue specificity in mitochondrial translation. Most of these gene defects result in histological abnormalities and multiple respiratory chain defects in the affected organs. The clinical phenotypes are usually early-onset, severe, and often fatal, implying the importance of mitochondrial translation from birth. However, some rare, reversible infantile mitochondrial diseases are caused by very specific defects of mitochondrial translation. An unbiased genetic approach (whole exome sequencing, RNA sequencing) combined with proteomics and functional studies revealed novel factors involved in mitochondrial translation which contribute to the clinical manifestation and recovery in these rare reversible mitochondrial conditions.
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18
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Smith HS, Swint JM, Lalani SR, Yamal JM, de Oliveira Otto MC, Castellanos S, Taylor A, Lee BH, Russell HV. Clinical Application of Genome and Exome Sequencing as a Diagnostic Tool for Pediatric Patients: a Scoping Review of the Literature. Genet Med 2018; 21:3-16. [PMID: 29760485 DOI: 10.1038/s41436-018-0024-6] [Citation(s) in RCA: 80] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Accepted: 03/20/2018] [Indexed: 12/17/2022] Open
Abstract
PURPOSE Availability of clinical genomic sequencing (CGS) has generated questions about the value of genome and exome sequencing as a diagnostic tool. Analysis of reported CGS application can inform uptake and direct further research. This scoping literature review aims to synthesize evidence on the clinical and economic impact of CGS. METHODS PubMed, Embase, and Cochrane were searched for peer-reviewed articles published between 2009 and 2017 on diagnostic CGS for infant and pediatric patients. Articles were classified according to sample size and whether economic evaluation was a primary research objective. Data on patient characteristics, clinical setting, and outcomes were extracted and narratively synthesized. RESULTS Of 171 included articles, 131 were case reports, 40 were aggregate analyses, and 4 had a primary economic evaluation aim. Diagnostic yield was the only consistently reported outcome. Median diagnostic yield in aggregate analyses was 33.2% but varied by broad clinical categories and test type. CONCLUSION Reported CGS use has rapidly increased and spans diverse clinical settings and patient phenotypes. Economic evaluations support the cost-saving potential of diagnostic CGS. Multidisciplinary implementation research, including more robust outcome measurement and economic evaluation, is needed to demonstrate clinical utility and cost-effectiveness of CGS.
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Affiliation(s)
- Hadley Stevens Smith
- Baylor College of Medicine, The University of Texas School of Public Health, Houston, Texas, USA
| | - J Michael Swint
- The University of Texas School of Public Health, The Center for Clinical Research and Evidence-Based Medicine, The University of Texas McGovern Medical School, Houston, Texas, USA
| | - Seema R Lalani
- Baylor College of Medicine, Baylor Genetics Laboratory, Houston, Texas, USA
| | - Jose-Miguel Yamal
- The University of Texas School of Public Health, Houston, Texas, USA
| | | | | | - Amy Taylor
- Texas Medical Center Library, Houston, Texas, USA
| | | | - Heidi V Russell
- Texas Children's Hospital, Baylor College of Medicine, Houston, Texas, USA
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19
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Bruni F, Di Meo I, Bellacchio E, Webb BD, McFarland R, Chrzanowska‐Lightowlers ZM, He L, Skorupa E, Moroni I, Ardissone A, Walczak A, Tyynismaa H, Isohanni P, Mandel H, Prokisch H, Haack T, Bonnen PE, Enrico B, Pronicka E, Ghezzi D, Taylor RW, Diodato D. Clinical, biochemical, and genetic features associated with VARS2-related mitochondrial disease. Hum Mutat 2018; 39:563-578. [PMID: 29314548 PMCID: PMC5873438 DOI: 10.1002/humu.23398] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Revised: 12/21/2017] [Accepted: 12/28/2017] [Indexed: 01/17/2023]
Abstract
In recent years, an increasing number of mitochondrial disorders have been associated with mutations in mitochondrial aminoacyl-tRNA synthetases (mt-aaRSs), which are key enzymes of mitochondrial protein synthesis. Bi-allelic functional variants in VARS2, encoding the mitochondrial valyl tRNA-synthetase, were first reported in a patient with psychomotor delay and epilepsia partialis continua associated with an oxidative phosphorylation (OXPHOS) Complex I defect, before being described in a patient with a neonatal form of encephalocardiomyopathy. Here we provide a detailed genetic, clinical, and biochemical description of 13 patients, from nine unrelated families, harboring VARS2 mutations. All patients except one, who manifested with a less severe disease course, presented at birth exhibiting severe encephalomyopathy and cardiomyopathy. Features included hypotonia, psychomotor delay, seizures, feeding difficulty, abnormal cranial MRI, and elevated lactate. The biochemical phenotype comprised a combined Complex I and Complex IV OXPHOS defect in muscle, with patient fibroblasts displaying normal OXPHOS activity. Homology modeling supported the pathogenicity of VARS2 missense variants. The detailed description of this cohort further delineates our understanding of the clinical presentation associated with pathogenic VARS2 variants and we recommend that this gene should be considered in early-onset mitochondrial encephalomyopathies or encephalocardiomyopathies.
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Affiliation(s)
- Francesco Bruni
- Wellcome Centre for Mitochondrial ResearchInstitute of NeuroscienceNewcastle UniversityNewcastle upon TyneUnited Kingdom
| | - Ivano Di Meo
- Molecular Neurogenetics UnitFoundation IRCCS Neurological Institute C. BestaMilanItaly
| | - Emanuele Bellacchio
- Genetics and Rare DiseasesResearch Division‘Bambino Gesù’ Children HospitalRomeItaly
| | - Bryn D. Webb
- Department of Genetics and Genomic SciencesIcahn School of Medicine at Mount SinaiNew YorkNew York
| | - Robert McFarland
- Wellcome Centre for Mitochondrial ResearchInstitute of NeuroscienceNewcastle UniversityNewcastle upon TyneUnited Kingdom
| | | | - Langping He
- Wellcome Centre for Mitochondrial ResearchInstitute of NeuroscienceNewcastle UniversityNewcastle upon TyneUnited Kingdom
| | - Ewa Skorupa
- Department of BiochemistryRadioimmunology and Experimental MedicineThe Children's Memorial Health InstituteWarsawPoland
| | - Isabella Moroni
- Child Neurology UnitFoundation IRCCS Neurological Institute “C. Besta”MilanItaly
| | - Anna Ardissone
- Molecular Neurogenetics UnitFoundation IRCCS Neurological Institute C. BestaMilanItaly
- Child Neurology UnitFoundation IRCCS Neurological Institute “C. Besta”MilanItaly
- Department of Molecular and Translational Medicine DIMETUniversity of Milan‐BicoccaMilanItaly
| | - Anna Walczak
- Department of Medical GeneticsCentre of BiostructureMedical University of WarsawWarsawPoland
| | - Henna Tyynismaa
- Research Programs UnitMolecular NeurologyUniversity of HelsinkiHelsinkiFinland
| | - Pirjo Isohanni
- Research Programs UnitMolecular NeurologyUniversity of HelsinkiHelsinkiFinland
- Department of Pediatric NeurologyChildren's HospitalUniversity of Helsinki and Helsinki University HospitalHelsinkiFinland
| | - Hanna Mandel
- Institute of Human Genetics and Metabolic DiseasesGalilee Medical CenterNahariyaIsrael
| | - Holger Prokisch
- Institute of Human GeneticsTechnische Universität MünchenMunichGermany
- Institute of Human GeneticsHelmholtz Zentrum MünchenNeuherbergGermany
| | - Tobias Haack
- Institute of Human GeneticsHelmholtz Zentrum MünchenNeuherbergGermany
| | - Penelope E. Bonnen
- Department of Molecular and Human GeneticsBaylor College of MedicineHoustonTexas
| | - Bertini Enrico
- Unit of Neuromuscular and Neurodegenerative DisordersLaboratory of Molecular Medicine‘Bambino Ges.’ Children's Research HospitalRomeItaly
| | - Ewa Pronicka
- Department of PediatricsNutrition and Metabolic DiseasesThe Children's Memorial Health InstituteWarsawPoland
| | - Daniele Ghezzi
- Molecular Neurogenetics UnitFoundation IRCCS Neurological Institute C. BestaMilanItaly
- Department of Pathophysiology and TransplantationUniversity of MilanMilanItaly
| | - Robert W. Taylor
- Wellcome Centre for Mitochondrial ResearchInstitute of NeuroscienceNewcastle UniversityNewcastle upon TyneUnited Kingdom
| | - Daria Diodato
- Unit of Neuromuscular and Neurodegenerative DisordersLaboratory of Molecular Medicine‘Bambino Ges.’ Children's Research HospitalRomeItaly
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20
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Abstract
INTRODUCTION Combined oxidative phosphorylation deficiency 20 (COXPD20) is a mitochondrial respiratory chain complex (RC) disorder, caused by disease-causing variants in the VARS2 gene, which encodes a mitochondrial aminoacyl-tRNA synthetase. Here we describe a patient with fatal mitochondrial encephalopathy caused by a homozygous VARS2 gene missense variant. CASE REPORT We report the case of a girl, the first child of non-consanguineous and healthy parents, born from an uneventful term pregnancy, who presented, in the neonatal period, major hypotonia and microcephaly. At 4 months of age she showed poor eye contact, nystagmus, global psychomotor development delay and failure to thrive, without dysmorphic features. Focal seizures started at 24 months which evolved to a severe epileptic encephalopathy and finally to super refractory status epilepticus, leading to her death at 28 months of age. Etiologic investigation encompassing metabolic and genetic causes failed to disclose a diagnosis. Post-mortem exome sequencing allowed the identification of a pathogenic variant in VARS2 gene in the homozygous state (c.1100C > T, p.Thr367Ile) in the patient, inherited from her heterozygous parents, leading to the diagnosis of COXPD2. CONCLUSION To the best of our knowledge, this is the fifth case described in the literature of a child with disease-causing variant in VARS2. With this report we expand the knowledge about the phenotype associated with this very rare mitochondrial defect, further emphasizing the use of exome sequencing as a very powerful diagnostic tool.
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21
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Boczonadi V, Jennings MJ, Horvath R. The role of tRNA synthetases in neurological and neuromuscular disorders. FEBS Lett 2018; 592:703-717. [PMID: 29288497 PMCID: PMC5873386 DOI: 10.1002/1873-3468.12962] [Citation(s) in RCA: 63] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2017] [Revised: 12/06/2017] [Accepted: 12/21/2017] [Indexed: 12/11/2022]
Abstract
Aminoacyl‐tRNA synthetases (ARSs) are ubiquitously expressed enzymes responsible for charging tRNAs with their cognate amino acids, therefore essential for the first step in protein synthesis. Although the majority of protein synthesis happens in the cytosol, an additional translation apparatus is required to translate the 13 mitochondrial DNA‐encoded proteins important for oxidative phosphorylation. Most ARS genes in these cellular compartments are distinct, but two genes are common, encoding aminoacyl‐tRNA synthetases of glycine (GARS) and lysine (KARS) in both mitochondria and the cytosol. Mutations in the majority of the 37 nuclear‐encoded human ARS genes have been linked to a variety of recessive and dominant tissue‐specific disorders. Current data indicate that impaired enzyme function could explain the pathogenicity, however not all pathogenic ARSs mutations result in deficient catalytic function; thus, the consequences of mutations may arise from other molecular mechanisms. The peripheral nerves are frequently affected, as illustrated by the high number of mutations in cytosolic and bifunctional tRNA synthetases causing Charcot–Marie–Tooth disease (CMT). Here we provide insights on the pathomechanisms of CMT‐causing tRNA synthetases with specific focus on the two bifunctional tRNA synthetases (GARS, KARS).
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Affiliation(s)
- Veronika Boczonadi
- Wellcome Centre for Mitochondrial Research, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK
| | - Matthew J Jennings
- Wellcome Centre for Mitochondrial Research, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK
| | - Rita Horvath
- Wellcome Centre for Mitochondrial Research, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK
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22
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Meyer-Schuman R, Antonellis A. Emerging mechanisms of aminoacyl-tRNA synthetase mutations in recessive and dominant human disease. Hum Mol Genet 2017; 26:R114-R127. [PMID: 28633377 PMCID: PMC5886470 DOI: 10.1093/hmg/ddx231] [Citation(s) in RCA: 112] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Revised: 06/09/2017] [Accepted: 06/12/2017] [Indexed: 12/29/2022] Open
Abstract
Aminoacyl-tRNA synthetases (ARSs) are responsible for charging amino acids to cognate tRNA molecules, which is the essential first step of protein translation. Interestingly, mutations in genes encoding ARS enzymes have been implicated in a broad spectrum of human inherited diseases. Bi-allelic mutations in ARSs typically cause severe, early-onset, recessive diseases that affect a wide range of tissues. The vast majority of these mutations show loss-of-function effects and impair protein translation. However, it is not clear how a subset cause tissue-specific phenotypes. In contrast, dominant ARS-mediated diseases specifically affect the peripheral nervous system-most commonly causing axonal peripheral neuropathy-and usually manifest later in life. These neuropathies are linked to heterozygosity for missense mutations in five ARS genes, which points to a shared mechanism of disease. However, it is not clear if a loss-of-function mechanism or a toxic gain-of-function mechanism is responsible for ARS-mediated neuropathy, or if a combination of these mechanisms operate on a mutation-specific basis. Here, we review our current understanding of recessive and dominant ARS-mediated disease. We also propose future directions for defining the molecular mechanisms of ARS mutations toward designing therapies for affected patient populations.
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Affiliation(s)
- Rebecca Meyer-Schuman
- Department of Human Genetics, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Anthony Antonellis
- Department of Human Genetics, University of Michigan Medical School, Ann Arbor, MI 48109, USA
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23
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Oprescu SN, Griffin LB, Beg AA, Antonellis A. Predicting the pathogenicity of aminoacyl-tRNA synthetase mutations. Methods 2016; 113:139-151. [PMID: 27876679 DOI: 10.1016/j.ymeth.2016.11.013] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2016] [Revised: 11/12/2016] [Accepted: 11/18/2016] [Indexed: 10/24/2022] Open
Abstract
Aminoacyl-tRNA synthetases (ARSs) are ubiquitously expressed, essential enzymes responsible for charging tRNA with cognate amino acids-the first step in protein synthesis. ARSs are required for protein translation in the cytoplasm and mitochondria of all cells. Surprisingly, mutations in 28 of the 37 nuclear-encoded human ARS genes have been linked to a variety of recessive and dominant tissue-specific disorders. Current data indicate that impaired enzyme function is a robust predictor of the pathogenicity of ARS mutations. However, experimental model systems that distinguish between pathogenic and non-pathogenic ARS variants are required for implicating newly identified ARS mutations in disease. Here, we outline strategies to assist in predicting the pathogenicity of ARS variants and urge cautious evaluation of genetic and functional data prior to linking an ARS mutation to a human disease phenotype.
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Affiliation(s)
- Stephanie N Oprescu
- Department of Human Genetics, University of Michigan Medical School, Ann Arbor, MI, United States
| | - Laurie B Griffin
- Cellular and Molecular Biology Program, University of Michigan Medical School, Ann Arbor, MI, United States; Medical Scientist Training Program, and University of Michigan Medical School, Ann Arbor, MI, United States
| | - Asim A Beg
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI, United States
| | - Anthony Antonellis
- Department of Human Genetics, University of Michigan Medical School, Ann Arbor, MI, United States; Cellular and Molecular Biology Program, University of Michigan Medical School, Ann Arbor, MI, United States.
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