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Perrier S, Guerrero K, Tran LT, Michell-Robinson MA, Legault G, Brais B, Sylvain M, Dorman J, Demos M, Köhler W, Pastinen T, Thiffault I, Bernard G. Solving inherited white matter disorder etiologies in the neurology clinic: Challenges and lessons learned using next-generation sequencing. Front Neurol 2023; 14:1148377. [PMID: 37077564 PMCID: PMC10108901 DOI: 10.3389/fneur.2023.1148377] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Accepted: 02/23/2023] [Indexed: 04/05/2023] Open
Abstract
IntroductionRare neurodevelopmental disorders, including inherited white matter disorders or leukodystrophies, often present a diagnostic challenge on a genetic level given the large number of causal genes associated with a range of disease subtypes. This study aims to demonstrate the challenges and lessons learned in the genetic investigations of leukodystrophies through presentation of a series of cases solved using exome or genome sequencing.MethodsEach of the six patients had a leukodystrophy associated with hypomyelination or delayed myelination on MRI, and inconclusive clinical diagnostic genetic testing results. We performed next generation sequencing (case-based exome or genome sequencing) to further investigate the genetic cause of disease.ResultsFollowing different lines of investigation, molecular diagnoses were obtained for each case, with patients harboring pathogenic variants in a range of genes including TMEM106B, GJA1, AGA, POLR3A, and TUBB4A. We describe the lessons learned in reaching the genetic diagnosis, including the importance of (a) utilizing proper multi-gene panels in clinical testing, (b) assessing the reliability of biochemical assays in supporting diagnoses, and (c) understanding the limitations of exome sequencing methods in regard to CNV detection and region coverage in GC-rich areas.DiscussionThis study illustrates the importance of applying a collaborative diagnostic approach by combining detailed phenotyping data and metabolic results from the clinical environment with advanced next generation sequencing analysis techniques from the research environment to increase the diagnostic yield in patients with genetically unresolved leukodystrophies.
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Affiliation(s)
- Stefanie Perrier
- Department of Neurology and Neurosurgery, McGill University, Montreal, QC, Canada
- Child Health and Human Development Program, Research Institute of the McGill University Health Centre, Montreal, QC, Canada
| | - Kether Guerrero
- Department of Neurology and Neurosurgery, McGill University, Montreal, QC, Canada
- Child Health and Human Development Program, Research Institute of the McGill University Health Centre, Montreal, QC, Canada
| | - Luan T. Tran
- Department of Neurology and Neurosurgery, McGill University, Montreal, QC, Canada
- Child Health and Human Development Program, Research Institute of the McGill University Health Centre, Montreal, QC, Canada
| | - Mackenzie A. Michell-Robinson
- Department of Neurology and Neurosurgery, McGill University, Montreal, QC, Canada
- Child Health and Human Development Program, Research Institute of the McGill University Health Centre, Montreal, QC, Canada
| | - Geneviève Legault
- Department of Neurology and Neurosurgery, McGill University, Montreal, QC, Canada
- Child Health and Human Development Program, Research Institute of the McGill University Health Centre, Montreal, QC, Canada
- Department of Pediatrics, McGill University, Montreal, QC, Canada
| | - Bernard Brais
- Department of Neurology and Neurosurgery, McGill University, Montreal, QC, Canada
- Montreal Neurological Institute, McGill University, Montreal, QC, Canada
- Department of Human Genetics, McGill University, Montreal, QC, Canada
| | - Michel Sylvain
- Division of Pediatric Neurology, Centre Mère-Enfant Soleil du CHU de Québec - Université Laval, Québec City, QC, Canada
| | - James Dorman
- John H. Stroger Jr. Hospital of Cook County, Chicago, IL, United States
- Department of Neurological Sciences, Rush Medical College, Chicago, IL, United States
| | - Michelle Demos
- Division of Neurology, Department of Pediatrics, University of British Columbia, BC Children's Hospital, Vancouver, BC, Canada
| | - Wolfgang Köhler
- Leukodystrophy Center, University of Leipzig Medical Center, Leipzig, Germany
| | - Tomi Pastinen
- Genomic Medicine Center, Children's Mercy Hospital, Kansas City, MO, United States
- University of Missouri Kansas City School of Medicine, Kansas City, MO, United States
| | - Isabelle Thiffault
- Genomic Medicine Center, Children's Mercy Hospital, Kansas City, MO, United States
- University of Missouri Kansas City School of Medicine, Kansas City, MO, United States
- Department of Pathology and Laboratory Medicine, Children's Mercy Hospital, Kansas City, MO, United States
- Isabelle Thiffault
| | - Geneviève Bernard
- Department of Neurology and Neurosurgery, McGill University, Montreal, QC, Canada
- Child Health and Human Development Program, Research Institute of the McGill University Health Centre, Montreal, QC, Canada
- Department of Pediatrics, McGill University, Montreal, QC, Canada
- Department of Human Genetics, McGill University, Montreal, QC, Canada
- Department of Specialized Medicine, Division of Medical Genetics, McGill University Health Center, Montreal, QC, Canada
- *Correspondence: Geneviève Bernard
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2
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Fellner A, Goldberg Y, Lev D, Basel-Salmon L, Shor O, Benninger F. In-silico phenotype prediction by normal mode variant analysis in TUBB4A-related disease. Sci Rep 2022; 12:58. [PMID: 34997144 PMCID: PMC8741991 DOI: 10.1038/s41598-021-04337-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2021] [Accepted: 12/21/2021] [Indexed: 11/09/2022] Open
Abstract
TUBB4A-associated disorder is a rare condition affecting the central nervous system. It displays a wide phenotypic spectrum, ranging from isolated late-onset torsion dystonia to a severe early-onset disease with developmental delay, neurological deficits, and atrophy of the basal ganglia and cerebellum, therefore complicating variant interpretation and phenotype prediction in patients carrying TUBB4A variants. We applied entropy-based normal mode analysis (NMA) to investigate genotype–phenotype correlations in TUBB4A-releated disease and to develop an in-silico approach to assist in variant interpretation and phenotype prediction in this disorder. Variants included in our analysis were those reported prior to the conclusion of data collection for this study in October 2019. All TUBB4A pathogenic missense variants reported in ClinVar and Pubmed, for which associated clinical information was available, and all benign/likely benign TUBB4A missense variants reported in ClinVar, were included in the analysis. Pathogenic variants were divided into five phenotypic subgroups. In-silico point mutagenesis in the wild-type modeled protein structure was performed for each variant. Wild-type and mutated structures were analyzed by coarse-grained NMA to quantify protein stability as entropy difference value (ΔG) for each variant. Pairwise ΔG differences between all variant pairs in each structural cluster were calculated and clustered into dendrograms. Our search yielded 41 TUBB4A pathogenic variants in 126 patients, divided into 11 partially overlapping structural clusters across the TUBB4A protein. ΔG-based cluster analysis of the NMA results revealed a continuum of genotype–phenotype correlation across each structural cluster, as well as in transition areas of partially overlapping structural clusters. Benign/likely benign variants were integrated into the genotype–phenotype continuum as expected and were clearly separated from pathogenic variants. We conclude that our results support the incorporation of the NMA-based approach used in this study in the interpretation of variant pathogenicity and phenotype prediction in TUBB4A-related disease. Moreover, our results suggest that NMA may be of value in variant interpretation in additional monogenic conditions.
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Affiliation(s)
- Avi Fellner
- Raphael Recanati Genetics Institute, Rabin Medical Center, Beilinson Hospital, 49100, Petah Tikva, Israel. .,Department of Neurology, Rabin Medical Center, Beilinson Hospital, 49100, Petah Tikva, Israel.
| | - Yael Goldberg
- Raphael Recanati Genetics Institute, Rabin Medical Center, Beilinson Hospital, 49100, Petah Tikva, Israel.,Sackler Faculty of Medicine, Tel-Aviv University, 69978, Tel-Aviv, Israel
| | - Dorit Lev
- Sackler Faculty of Medicine, Tel-Aviv University, 69978, Tel-Aviv, Israel.,Metabolic-Neurogenetic Clinic, Wolfson Medical Center, 58220, Holon, Israel.,Rina Mor Institute of Medical Genetics, Wolfson Medical Center, 58220, Holon, Israel
| | - Lina Basel-Salmon
- Raphael Recanati Genetics Institute, Rabin Medical Center, Beilinson Hospital, 49100, Petah Tikva, Israel.,Sackler Faculty of Medicine, Tel-Aviv University, 69978, Tel-Aviv, Israel.,Felsenstein Medical Research Center, 49100, Petah Tikva, Israel
| | - Oded Shor
- Department of Neurology, Rabin Medical Center, Beilinson Hospital, 49100, Petah Tikva, Israel.,Sackler Faculty of Medicine, Tel-Aviv University, 69978, Tel-Aviv, Israel.,Felsenstein Medical Research Center, 49100, Petah Tikva, Israel
| | - Felix Benninger
- Department of Neurology, Rabin Medical Center, Beilinson Hospital, 49100, Petah Tikva, Israel.,Sackler Faculty of Medicine, Tel-Aviv University, 69978, Tel-Aviv, Israel.,Felsenstein Medical Research Center, 49100, Petah Tikva, Israel
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3
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Lopez-Juarez A, Gonzalez-Vega A, Kleinert-Altamirano A, Piazza V, Garduno-Robles A, Alata M, Villaseñor-Mora C, Eguibar JR, Cortes C, Padierna LC, Hernandez VH. Auditory impairment in H-ABC tubulinopathy. J Comp Neurol 2020; 529:957-968. [PMID: 32681585 DOI: 10.1002/cne.24990] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Revised: 06/12/2020] [Accepted: 07/10/2020] [Indexed: 12/20/2022]
Abstract
Hypomyelination with atrophy of the basal ganglia and cerebellum (H-ABC) is a neurodegenerative disease due to mutations in TUBB4A. Patients suffer from extrapyramidal movements, spasticity, ataxia, and cognitive deficits. Magnetic resonance imaging features are hypomyelination and atrophy of the striatum and cerebellum. A correlation between the mutations and their cellular, tissue and organic effects is largely missing. The effects of these mutations on sensory functions have not been described so far. We have previously reported a rat carrying a TUBB4A (A302T) mutation and sharing most of the clinical and radiological signs with H-ABC patients. Here, for the first time, we did a comparative study of the hearing function in an H-ABC patient and in this mutant model. By analyzing hearing function, we found that there are no significant differences in the auditory brainstem response (ABR) thresholds between mutant rats and WT controls. Nevertheless, ABRs show longer latencies in central waves (II-IV) that in some cases disappear when compared to WT. The patient also shows abnormal AEPs presenting only Waves I and II. Distortion product of otoacoustic emissions and immunohistochemistry in the rat show that the peripheral hearing function and morphology of the organ of Corti are normal. We conclude that the tubulin mutation severely impairs the central hearing pathway most probably by progressive central white matter degeneration. Hearing function might be affected in a significant fraction of patients with H-ABC; therefore, screening for auditory function should be done on patients with tubulinopathies to evaluate hearing support therapies.
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Affiliation(s)
| | - Arturo Gonzalez-Vega
- Division of Sciences and Engineering, University of Guanajuato, Guanajuato, Mexico
| | | | | | - Angeles Garduno-Robles
- Division of Sciences and Engineering, University of Guanajuato, Guanajuato, Mexico.,Center of Research in Optics, Leon, Mexico
| | | | | | - Jose R Eguibar
- Institute of Physiology, Benemérita Universidad Autónoma de Puebla, Puebla, Mexico.,Vicerrectoría de Investigación y Estudios de Posgrado, Benemérita Universidad Autónoma de Puebla, Puebla, Mexico
| | - Carmen Cortes
- Institute of Physiology, Benemérita Universidad Autónoma de Puebla, Puebla, Mexico
| | - Luis Carlos Padierna
- Division of Sciences and Engineering, University of Guanajuato, Guanajuato, Mexico
| | - Victor H Hernandez
- Division of Sciences and Engineering, University of Guanajuato, Guanajuato, Mexico
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4
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Yamamoto-Shimojima K, Imaizumi T, Aoki Y, Inoue K, Kaname T, Okuno Y, Muramatsu H, Kato K, Yamamoto T. Elucidation of the pathogenic mechanism and potential treatment strategy for a female patient with spastic paraplegia derived from a single-nucleotide deletion in PLP1. J Hum Genet 2019; 64:665-671. [PMID: 31004103 DOI: 10.1038/s10038-019-0600-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2018] [Revised: 03/24/2019] [Accepted: 04/04/2019] [Indexed: 11/09/2022]
Abstract
Pelizaeus-Merzbacher disease (PMD) is an X-linked recessive disorder caused by abnormalities in the gene PLP1. Most females harboring heterozygous PLP1 abnormalities are basically asymptomatic. However, as a result of abnormal patterns of X-chromosome inactivation, it is possible for some female carriers to be symptomatic. Whole-exome sequencing of a female patient with unknown spastic paraplegia was performed to obtain a molecular diagnosis. As a result, a de novo heterozygous single-nucleotide deletion in PLP1 [NM_000533.5(PLP1_v001):c.783del; p.Thr262Leufs*20] was identified. RNA sequencing was performed in a patient-derived lymphoblastoid cell line, confirming mono-allelic expression of the mutated allele and abnormal inactivation of the wild-type allele. The patient-derived lymphoblastoid cell line was then treated with VX680 or 5azadC, which resulted in restored expression of the wild-type allele. These two agents thus have the potential to reverse inappropriately-skewed inactivation of the X-chromosome.
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Affiliation(s)
- Keiko Yamamoto-Shimojima
- Japan Society for the Promotion of Science (RPD), Tokyo, 160-8582, Japan.,Institute of Medical Genetics, Tokyo Women's Medical University, Tokyo, 162-8666, Japan.,Tokyo Women's Medical University, Institute of Integrated Medical Sciences, Tokyo, 162-8666, Japan
| | - Taichi Imaizumi
- Department of Gene Medicine, Graduate school of Medicine, Tokyo Women's Medical University, Tokyo, 162-8666, Japan.,Department of Pediatrics, St. Marianna University School of Medicine, Kawasaki, 216-8511, Japan
| | - Yusuke Aoki
- Department of Neurology, Aichi Children's Health and Medical Center, Aichi, 474-8710, Japan
| | - Ken Inoue
- Department of Mental Retardation and Birth Defect Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Kodaira, 187-0031, Japan
| | - Tadashi Kaname
- Department of Genome Medicine, National Center for Child Health and Development, Tokyo, 157-8535, Japan
| | - Yusuke Okuno
- Center for Advanced Medicine and Clinical Research, Department of Advanced Medicine, Nagoya University Hospital, Nagoya, 466-8560, Japan
| | - Hideki Muramatsu
- Department of Pediatrics, Nagoya University Graduate School of Medicine, Nagoya, 466-8560, Japan
| | - Kohji Kato
- Department of Pediatrics, Nagoya University Graduate School of Medicine, Nagoya, 466-8560, Japan
| | - Toshiyuki Yamamoto
- Institute of Medical Genetics, Tokyo Women's Medical University, Tokyo, 162-8666, Japan. .,Tokyo Women's Medical University, Institute of Integrated Medical Sciences, Tokyo, 162-8666, Japan. .,Department of Gene Medicine, Graduate school of Medicine, Tokyo Women's Medical University, Tokyo, 162-8666, Japan.
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5
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Karthikkeyan G, Subbannayya Y, Najar MA, Mohanty V, Pinto SM, Arunachalam C, Prasad TSK, Murthy KR. Human Optic Nerve: An Enhanced Proteomic Expression Profile. OMICS-A JOURNAL OF INTEGRATIVE BIOLOGY 2018; 22:642-652. [PMID: 30346883 DOI: 10.1089/omi.2018.0130] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Ophthalmology and visual health are new frontiers for postgenomic research and technologies such as proteomics. In this context, the optic nerve and retina extend as the outgrowth of the brain, wherein the latter receives the optical input and the former relays the information for processing. While efforts to understand the optic nerve proteome have been made earlier, there exists a lacuna in its biochemical composition and molecular functions. We report, in this study, a high-resolution mass spectrometry-based approach using an Orbitrap Fusion Tribrid mass spectrometer to elucidate the human optic nerve proteomic profile. Raw spectra were searched against NCBI Human RefSeq 75 database using SEQUEST HT and MASCOT algorithms. We identified nearly 35,000 peptides in human optic nerve samples, corresponding to 5682 proteins, of which 3222 proteins are being reported for the first time. Label-free quantification using spectral abundance pointed out to neuronal structural proteins such as myelin basic protein, glial fibrillary acidic protein, and proteolipid protein 1 as the most abundant proteins. We also identified several neurotransmitter receptors and postsynaptic density synaptosomal scaffold proteins. Pathway analysis revealed that a majority of the proteins are structural proteins and have catalytic and binding activity. This study is one of the largest proteomic profiles of the human optic nerve and offers the research community an initial baseline optic nerve proteome for further studies. This will also help understand the protein dynamics of the human optic nerve under normal conditions.
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Affiliation(s)
- Gayathree Karthikkeyan
- 1 Center for Systems Biology and Molecular Medicine, Yenepoya Research Centre, Yenepoya (Deemed to be University) , Mangalore, India
| | - Yashwanth Subbannayya
- 1 Center for Systems Biology and Molecular Medicine, Yenepoya Research Centre, Yenepoya (Deemed to be University) , Mangalore, India
| | - Mohd Altaf Najar
- 1 Center for Systems Biology and Molecular Medicine, Yenepoya Research Centre, Yenepoya (Deemed to be University) , Mangalore, India
| | - Varshasnata Mohanty
- 1 Center for Systems Biology and Molecular Medicine, Yenepoya Research Centre, Yenepoya (Deemed to be University) , Mangalore, India
| | - Sneha M Pinto
- 1 Center for Systems Biology and Molecular Medicine, Yenepoya Research Centre, Yenepoya (Deemed to be University) , Mangalore, India
| | - Cynthia Arunachalam
- 2 Department of Ophthalmology, Yenepoya Medical College, Yenepoya (Deemed to be University) , Mangalore, India
| | - Thottethodi Subrahmanya Keshava Prasad
- 1 Center for Systems Biology and Molecular Medicine, Yenepoya Research Centre, Yenepoya (Deemed to be University) , Mangalore, India .,3 Institute of Bioinformatics , International Tech Park, Bangalore, Karnataka, India
| | - Krishna R Murthy
- 3 Institute of Bioinformatics , International Tech Park, Bangalore, Karnataka, India .,4 Vittala International Institute of Ophthalmology , Bangalore, Karnataka, India .,5 Manipal Academy of Higher Education , Manipal, Karnataka, India
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6
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Curiel J, Rodríguez Bey G, Takanohashi A, Bugiani M, Fu X, Wolf NI, Nmezi B, Schiffmann R, Bugaighis M, Pierson T, Helman G, Simons C, van der Knaap MS, Liu J, Padiath Q, Vanderver A. TUBB4A mutations result in specific neuronal and oligodendrocytic defects that closely match clinically distinct phenotypes. Hum Mol Genet 2018; 26:4506-4518. [PMID: 28973395 DOI: 10.1093/hmg/ddx338] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Accepted: 08/24/2017] [Indexed: 12/16/2022] Open
Abstract
Hypomyelinating leukodystrophies are heritable disorders defined by lack of development of brain myelin, but the cellular mechanisms of hypomyelination are often poorly understood. Mutations in TUBB4A, encoding the tubulin isoform tubulin beta class IVA (Tubb4a), result in the symptom complex of hypomyelination with atrophy of basal ganglia and cerebellum (H-ABC). Additionally, TUBB4A mutations are known to result in a broad phenotypic spectrum, ranging from primary dystonia (DYT4), isolated hypomyelination with spastic quadriplegia, and an infantile onset encephalopathy, suggesting multiple cell types may be involved. We present a study of the cellular effects of TUBB4A mutations responsible for H-ABC (p.Asp249Asn), DYT4 (p.Arg2Gly), a severe combined phenotype with hypomyelination and encephalopathy (p.Asn414Lys), as well as milder phenotypes causing isolated hypomyelination (p.Val255Ile and p.Arg282Pro). We used a combination of histopathological, biochemical and cellular approaches to determine how these different mutations may have variable cellular effects in neurons and/or oligodendrocytes. Our results demonstrate that specific mutations lead to either purely neuronal, combined neuronal and oligodendrocytic or purely oligodendrocytic defects that closely match their respective clinical phenotypes. Thus, the DYT4 mutation that leads to phenotypes attributable to neuronal dysfunction results in altered neuronal morphology, but with unchanged tubulin quantity and polymerization, with normal oligodendrocyte morphology and myelin gene expression. Conversely, mutations associated with isolated hypomyelination (p.Val255Ile and p.Arg282Pro) and the severe combined phenotype (p.Asn414Lys) resulted in normal neuronal morphology but were associated with altered oligodendrocyte morphology, myelin gene expression, and microtubule dysfunction. The H-ABC mutation (p.Asp249Asn) that exhibits a combined neuronal and myelin phenotype had overlapping cellular defects involving both neuronal and oligodendrocyte cell types in vitro. Only mutations causing hypomyelination phenotypes showed altered microtubule dynamics and acted through a dominant toxic gain of function mechanism. The DYT4 mutation had no impact on microtubule dynamics suggesting a distinct mechanism of action. In summary, the different clinical phenotypes associated with TUBB4A reflect the selective and specific cellular effects of the causative mutations. Cellular specificity of disease pathogenesis is relevant to developing targeted treatments for this disabling condition.
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Affiliation(s)
- Julian Curiel
- Center for Neuroscience Research, Children's National Health System, Children's Research Institute, Washington, DC 20010, USA
| | | | - Asako Takanohashi
- Center for Genetic Medicine Research, Children's National Health System, Children's Research Institute, Washington, DC 20010, USA.,Division of Neurology, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | | | - Xiaoqin Fu
- Center for Neuroscience Research, Children's National Health System, Children's Research Institute, Washington, DC 20010, USA
| | - Nicole I Wolf
- VU University Medical Center, Amsterdam, The Netherlands
| | - Bruce Nmezi
- Department of Human Genetics, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Raphael Schiffmann
- Institute of Metabolic Disease, Baylor Scott & White Research Institute, Dallas, TX 75204, USA
| | - Mona Bugaighis
- Center for Neuroscience Research, Children's National Health System, Children's Research Institute, Washington, DC 20010, USA
| | - Tyler Pierson
- Departments of Pediatrics and Neurology, Cedar Sinai Medical Center, Board of Governors Regenerative Medicine Institute, Los Angeles, CA 90048, USA
| | - Guy Helman
- Center for Genetic Medicine Research, Children's National Health System, Children's Research Institute, Washington, DC 20010, USA.,Institute for Molecular Bioscience, University of Queensland, Brisbane, Australia.,Department of Neurology, Children's National Health System, Washington, DC 20010, USA
| | - Cas Simons
- Institute for Molecular Bioscience, University of Queensland, Brisbane, Australia
| | | | - Judy Liu
- Center for Neuroscience Research, Children's National Health System, Children's Research Institute, Washington, DC 20010, USA
| | - Quasar Padiath
- Department of Human Genetics, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Adeline Vanderver
- Center for Genetic Medicine Research, Children's National Health System, Children's Research Institute, Washington, DC 20010, USA.,Division of Neurology, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA.,Department of Neurology, Children's National Health System, Washington, DC 20010, USA.,Perlman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
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7
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A novel TUBB4A mutation G96R identified in a patient with hypomyelinating leukodystrophy onset beyond adolescence. Hum Genome Var 2017; 4:17035. [PMID: 28791129 PMCID: PMC5540734 DOI: 10.1038/hgv.2017.35] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Revised: 06/26/2017] [Accepted: 06/26/2017] [Indexed: 12/22/2022] Open
Abstract
The tubulin beta-4A gene (TUBB4A) is associated with two different clinical conditions, dystonia type 4 (DYT4) and hypomyelination with atrophy of the basal ganglia and cerebellum (H-ABC). We identified a novel TUBB4A mutation, c.286G>A (p.G96R), in an adult male patient who suffered neurological symptoms beyond adolescence. This patient shows intermediate clinical features between DYT4 and H-ABC, suggesting that the TUBB4A disorder would constitute a spectrum disorder.
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8
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Mutations in RARS cause a hypomyelination disorder akin to Pelizaeus-Merzbacher disease. Eur J Hum Genet 2017; 25:1134-1141. [PMID: 28905880 DOI: 10.1038/ejhg.2017.119] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Revised: 06/18/2017] [Accepted: 06/27/2017] [Indexed: 12/11/2022] Open
Abstract
Pelizaeus-Merzbacher disease (PMD) is a rare Mendelian disorder characterised by central nervous system hypomyelination. PMD typically manifests in infancy or early childhood and is caused by mutations in proteolipid protein-1 (PLP1). However, variants in several other genes including gap junction protein gamma 2 (GJC2) can also cause a similar phenotype and are referred to PMD-like disease (PMLD). Whole-exome sequencing in two siblings presenting with clinical symptoms of PMD revealed a homozygous variant in the arginyl-tRNA synthetase (RARS) gene: NM_002887.3: c.[5A>G] p.(Asp2Gly). Subsequent screening of a PMD cohort without a genetic diagnosis identified an unrelated individual with novel compound heterozygous variants including a missense variant c.[1367C>T] p.(Ser456Leu) and a de novo deletion c.[1846_1847delTA] p.(Tyr616Leufs*6). Protein levels of RARS and the multi-tRNA synthetase complex into which it assembles were found to be significantly reduced by 80 and 90% by western blotting and Blue native-PAGE respectively using patient fibroblast extracts. As RARS is involved in protein synthesis whereby it attaches arginine to its cognate tRNA, patient cells were studied to determine their ability to proliferate with limiting amounts of this essential amino acid. Patient fibroblasts cultured in medium with limited arginine at 30 °C and 40 °C, showed a significant decrease in fibroblast proliferation (P<0.001) compared to control cells, suggestive of inefficiency of protein synthesis in the patient cells. Our functional studies provide further evidence that RARS is a PMD-causing gene.
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9
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Chamova T, Kancheva D, Guergueltcheva V, Mitev V, Azmanov DN, Kalaydjieva L, Jordanova A, Tournev I. Reply: Mutations in TUBB4A and spastic paraplegia. Mov Disord 2015; 30:1858-9. [PMID: 26477690 DOI: 10.1002/mds.26442] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2015] [Accepted: 09/07/2015] [Indexed: 11/06/2022] Open
Affiliation(s)
- Teodora Chamova
- Medical University of Sofia, Faculty of Medicine, Department of Neurology, Clinic of Neurology, University Hospital Alexandrovska, Sofia, Bulgaria
| | - Dahlia Kancheva
- Molecular Neurogenomics Group, Department of Molecular Genetics, Antwerp, Belgium.,Neurogenetics Laboratory, Institute Born-Bunge, University of Antwerp, Antwerp, Belgium.,Department of Medical Chemistry and Biochemistry, Molecular Medicine Center, Medical University-Sofia, Sofia, Bulgaria
| | | | - Vanio Mitev
- Department of Medical Chemistry and Biochemistry, Molecular Medicine Center, Medical University-Sofia, Sofia, Bulgaria
| | - Dimitar N Azmanov
- Department of Diagnostic Genomics, PathWest, QEII Medical Centre, Nedlands, WA, Australia.,Harry Perkins Institute of Medical Research and Centre for Medical Research, The University of Western Australia, Perth, Australia
| | - Luba Kalaydjieva
- Harry Perkins Institute of Medical Research and Centre for Medical Research, The University of Western Australia, Perth, Australia
| | - Albena Jordanova
- Molecular Neurogenomics Group, Department of Molecular Genetics, Antwerp, Belgium.,Neurogenetics Laboratory, Institute Born-Bunge, University of Antwerp, Antwerp, Belgium.,Department of Medical Chemistry and Biochemistry, Molecular Medicine Center, Medical University-Sofia, Sofia, Bulgaria
| | - Ivailo Tournev
- Medical University of Sofia, Faculty of Medicine, Department of Neurology, Clinic of Neurology, University Hospital Alexandrovska, Sofia, Bulgaria.,Department of Cognitive Science and Psychology, New Bulgarian University, Sofia, Bulgaria
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10
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Lossos A, Elazar N, Lerer I, Schueler-Furman O, Fellig Y, Glick B, Zimmerman BE, Azulay H, Dotan S, Goldberg S, Gomori JM, Ponger P, Newman JP, Marreed H, Steck AJ, Schaeren-Wiemers N, Mor N, Harel M, Geiger T, Eshed-Eisenbach Y, Meiner V, Peles E. Myelin-associated glycoprotein gene mutation causes Pelizaeus-Merzbacher disease-like disorder. Brain 2015; 138:2521-36. [PMID: 26179919 DOI: 10.1093/brain/awv204] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2015] [Accepted: 05/27/2015] [Indexed: 01/07/2023] Open
Abstract
Pelizaeus-Merzbacher disease is an X-linked hypomyelinating leukodystrophy caused by mutations or rearrangements in PLP1. It presents in infancy with nystagmus, jerky head movements, hypotonia and developmental delay evolving into spastic tetraplegia with optic atrophy and variable movement disorders. A clinically similar phenotype caused by recessive mutations in GJC2 is known as Pelizaeus-Merzbacher-like disease. Both genes encode proteins associated with myelin. We describe three siblings of a consanguineous family manifesting the typical infantile-onset Pelizaeus-Merzbacher disease-like phenotype slowly evolving into a form of complicated hereditary spastic paraplegia with mental retardation, dysarthria, optic atrophy and peripheral neuropathy in adulthood. Magnetic resonance imaging and spectroscopy were consistent with a demyelinating leukodystrophy. Using genetic linkage and exome sequencing, we identified a homozygous missense c.399C>G; p.S133R mutation in MAG. This gene, previously associated with hereditary spastic paraplegia, encodes myelin-associated glycoprotein, which is involved in myelin maintenance and glia-axon interaction. This mutation is predicted to destabilize the protein and affect its tertiary structure. Examination of the sural nerve biopsy sample obtained in childhood in the oldest sibling revealed complete absence of myelin-associated glycoprotein accompanied by ill-formed onion-bulb structures and a relatively thin myelin sheath of the affected axons. Immunofluorescence, cell surface labelling, biochemical analysis and mass spectrometry-based proteomics studies in a variety of cell types demonstrated a devastating effect of the mutation on post-translational processing, steady state expression and subcellular localization of myelin-associated glycoprotein. In contrast to the wild-type protein, the p.S133R mutant was retained in the endoplasmic reticulum and was subjected to endoplasmic reticulum-associated protein degradation by the proteasome. Our findings identify involvement of myelin-associated glycoprotein in this family with a disorder affecting the central and peripheral nervous system, and suggest that loss of the protein function is responsible for the unique clinical phenotype.
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Affiliation(s)
- Alexander Lossos
- 1 Department of Neurology and Agnes Ginges Centre for Human Neurogenetics, Hebrew University-Hadassah Medical Centre, Jerusalem, Israel
| | - Nimrod Elazar
- 2 Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Israela Lerer
- 3 Department of Genetics and Metabolic Diseases, Hebrew University-Hadassah Medical Centre, Jerusalem, Israel
| | - Ora Schueler-Furman
- 4 Department of Microbiology and Molecular Genetics, Institute for Medical Research Israel-Canada, Faculty of Medicine, Hebrew University, Jerusalem, Israel
| | - Yakov Fellig
- 5 Department of Pathology, Hebrew University-Hadassah Medical Centre, Jerusalem, Israel
| | - Benjamin Glick
- 6 Paediatric Neuromuscular Service, Alyn Paediatric Rehabilitation Centre, Jerusalem, Israel
| | - Bat-El Zimmerman
- 3 Department of Genetics and Metabolic Diseases, Hebrew University-Hadassah Medical Centre, Jerusalem, Israel
| | - Haim Azulay
- 5 Department of Pathology, Hebrew University-Hadassah Medical Centre, Jerusalem, Israel
| | - Shlomo Dotan
- 7 Department of Ophthalmology, Hebrew University-Hadassah Medical Centre, Jerusalem, Israel
| | - Sharon Goldberg
- 7 Department of Ophthalmology, Hebrew University-Hadassah Medical Centre, Jerusalem, Israel
| | - John M Gomori
- 8 Department of Radiology, Hebrew University-Hadassah Medical Centre, Jerusalem, Israel
| | - Penina Ponger
- 1 Department of Neurology and Agnes Ginges Centre for Human Neurogenetics, Hebrew University-Hadassah Medical Centre, Jerusalem, Israel
| | - J P Newman
- 1 Department of Neurology and Agnes Ginges Centre for Human Neurogenetics, Hebrew University-Hadassah Medical Centre, Jerusalem, Israel
| | - Hodaifah Marreed
- 3 Department of Genetics and Metabolic Diseases, Hebrew University-Hadassah Medical Centre, Jerusalem, Israel
| | - Andreas J Steck
- 9 Department of Biomedicine, University Hospital Basel, University of Basel, Switzerland
| | | | - Nofar Mor
- 2 Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Michal Harel
- 10 Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Tamar Geiger
- 10 Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Yael Eshed-Eisenbach
- 2 Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Vardiella Meiner
- 3 Department of Genetics and Metabolic Diseases, Hebrew University-Hadassah Medical Centre, Jerusalem, Israel
| | - Elior Peles
- 2 Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, Israel
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11
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Balint B, Bhatia KP. Isolated and combined dystonia syndromes - an update on new genes and their phenotypes. Eur J Neurol 2015; 22:610-7. [DOI: 10.1111/ene.12650] [Citation(s) in RCA: 75] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2014] [Accepted: 11/12/2014] [Indexed: 11/27/2022]
Affiliation(s)
- B. Balint
- Sobell Department of Motor Neuroscience and Movement Disorders; UCL Institute of Neurology; London UK
- Department of Neurology; University Hospital Heidelberg; Heidelberg Germany
| | - K. P. Bhatia
- Sobell Department of Motor Neuroscience and Movement Disorders; UCL Institute of Neurology; London UK
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