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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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Osório MJ, Goldman SA. Neurogenetics of Pelizaeus-Merzbacher disease. HANDBOOK OF CLINICAL NEUROLOGY 2018; 148:701-722. [PMID: 29478609 DOI: 10.1016/b978-0-444-64076-5.00045-4] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Pelizaeus-Merzbacher disease (PMD) is an X-linked disorder caused by mutations in the PLP1 gene, which encodes the proteolipid protein of myelinating oligodendroglia. PMD exhibits phenotypic variability that reflects its considerable genotypic heterogeneity, but all forms of the disease result in central hypomyelination associated with early neurologic dysfunction, progressive deterioration, and ultimately death. PMD has been classified into three major subtypes, according to the age of presentation: connatal PMD, classic PMD, and transitional PMD, combining features of both connatal and classic forms. Two other less severe phenotypes were subsequently described, including the spastic paraplegia syndrome and PLP1-null disease. These disorders may be associated with duplications, as well as with point, missense, and null mutations within the PLP1 gene. A number of clinically similar Pelizaeus-Merzbacher-like disorders (PMLD) are considered in the differential diagnosis of PMD, the most prominent of which is PMLD-1, caused by misexpression of the GJC2 gene encoding connexin-47. No effective therapy for PMD exists. Yet, as a relatively pure central nervous system hypomyelinating disorder, with limited involvement of the peripheral nervous system and little attendant neuronal pathology, PMD is an attractive therapeutic target for neural stem cell and glial progenitor cell transplantation, efforts at which are now underway in a number of centers internationally.
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Affiliation(s)
- M Joana Osório
- Center for Translational Neuromedicine and Department of Neurology, University of Rochester Medical Center, Rochester, NY, United States; Center for Translational Neuromedicine, University of Copenhagen Faculty of Health and Medical Sciences, Copenhagen, Denmark
| | - Steven A Goldman
- Center for Translational Neuromedicine and Department of Neurology, University of Rochester Medical Center, Rochester, NY, United States; Center for Translational Neuromedicine, University of Copenhagen Faculty of Health and Medical Sciences, Copenhagen, Denmark.
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Pavlidou E, Ramachandran V, Govender V, Wilson C, Das R, Vlachou V, Pavlou E, Saggar A, Mankad K, Kinali M. A novel PLP1 mutation associated with optic nerve enlargement in two siblings with Pelizaeus-Merzbacher disease: A new MRI finding. Brain Dev 2017; 39:271-274. [PMID: 27793435 DOI: 10.1016/j.braindev.2016.09.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Revised: 09/10/2016] [Accepted: 09/24/2016] [Indexed: 11/20/2022]
Abstract
Pelizaeus-Merzbacher disease (PMD) is a rare, X-linked disorder characterized by hypomyelination of the Central Nervous System due to mutations in the PLP1 gene. Certain mutations of the PLP1 gene correlate with specific clinical phenotypes and neuroimaging findings. We herein report a novel mutation of the PLP1 gene in two siblings with PMD associated with a rare and protean neuroimaging finding of optic nerve enlargement. To the best of our knowledge this is the first time that this novel mutation H133P of PLP1 gene is identified and clinically associated with optic nerve enlargement in PMD patients.
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Affiliation(s)
- Efterpi Pavlidou
- Department of Paediatric Neurology, Chelsea and Westminster NHS Foundation Trust, London, United Kingdom
| | - Vijaya Ramachandran
- South West Thames Regional Genetics Laboratory, St George's Hospital, NHS Foundation Trust, London, United Kingdom
| | - Veronica Govender
- Department of Paediatric Neurology, Chelsea and Westminster NHS Foundation Trust, London, United Kingdom
| | - Clare Wilson
- Department of Paediatric Ophthalmology, Chelsea and Westminster NHS Foundation Trust, London, United Kingdom
| | - Rini Das
- Department of Paediatric Neurology, Chelsea and Westminster NHS Foundation Trust, London, United Kingdom
| | - Victoria Vlachou
- Department of Paediatric Neurology, Chelsea and Westminster NHS Foundation Trust, London, United Kingdom
| | - Evangelos Pavlou
- Department of Paediatric Neurology, 2nd Paediatric Department, A.H.E.P.A Hospital, Aristotle University of Thessaloniki, Greece
| | - Anand Saggar
- South West Thames Regional Genetics Laboratory, St George's Hospital, NHS Foundation Trust, London, United Kingdom
| | - Kshitij Mankad
- Department of Neuroradiology, Great Ormond Street Hospital for Children NHS Foundation Trust, London, United Kingdom
| | - Maria Kinali
- Department of Paediatric Neurology, Chelsea and Westminster NHS Foundation Trust, London, United Kingdom.
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Gu S, Szafranski P, Akdemir ZC, Yuan B, Cooper ML, Magriñá MA, Bacino CA, Lalani SR, Breman AM, Smith JL, Patel A, Song RH, Bi W, Cheung SW, Carvalho CMB, Stankiewicz P, Lupski JR. Mechanisms for Complex Chromosomal Insertions. PLoS Genet 2016; 12:e1006446. [PMID: 27880765 PMCID: PMC5120786 DOI: 10.1371/journal.pgen.1006446] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2016] [Accepted: 10/24/2016] [Indexed: 12/21/2022] Open
Abstract
Chromosomal insertions are genomic rearrangements with a chromosome segment inserted into a non-homologous chromosome or a non-adjacent locus on the same chromosome or the other homologue, constituting ~2% of nonrecurrent copy-number gains. Little is known about the molecular mechanisms of their formation. We identified 16 individuals with complex insertions among 56,000 individuals tested at Baylor Genetics using clinical array comparative genomic hybridization (aCGH) and fluorescence in situ hybridization (FISH). Custom high-density aCGH was performed on 10 individuals with available DNA, and breakpoint junctions were fine-mapped at nucleotide resolution by long-range PCR and DNA sequencing in 6 individuals to glean insights into potential mechanisms of formation. We observed microhomologies and templated insertions at the breakpoint junctions, resembling the breakpoint junction signatures found in complex genomic rearrangements generated by replication-based mechanism(s) with iterative template switches. In addition, we analyzed 5 families with apparently balanced insertion in one parent detected by FISH analysis and found that 3 parents had additional small copy-number variants (CNVs) at one or both sides of the inserting fragments as well as at the inserted sites. We propose that replicative repair can result in interchromosomal complex insertions generated through chromothripsis-like chromoanasynthesis involving two or three chromosomes, and cause a significant fraction of apparently balanced insertions harboring small flanking CNVs. By traditional cytogenetic techniques, the incidence of microscopically visible chromosomal insertions was estimated to be 1 in 80,000 live births. More recently, by aCGH in conjunction with FISH confirmation of the aCGH findings, insertion events were demonstrated to occur much more frequently (1 in ~500 individuals tested). Although frequently detected, little is known about the molecular mechanisms of their formation. In this study, we identified 16 individuals with complex chromosomal insertions among 56,000 individuals tested at Baylor Genetics using clinical microarray analysis (CMA) and FISH. Custom high-density aCGH was performed on 10 individuals with available DNA, and breakpoint junctions were fine-mapped at nucleotide resolution by long-range PCR and DNA sequencing in 6 individuals to glean insights into potential mechanisms of formation. In addition, we analyzed 5 families with apparently balanced insertion in one parent detected by FISH analysis and found that 3 parents had additional small copy-number variants (CNVs) at one or both sides of the inserting fragments as well as at the inserted sites. We propose that replicative repair can result in interchromosomal complex insertions generated through chromothripsis-like chromoanasynthesis involving two or three chromosomes, and cause a significant fraction of apparently balanced insertions harboring small flanking CNVs.
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Affiliation(s)
- Shen Gu
- Department of Molecular & Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Przemyslaw Szafranski
- Department of Molecular & Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Zeynep Coban Akdemir
- Department of Molecular & Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Bo Yuan
- Department of Molecular & Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Mitchell L. Cooper
- Department of Molecular & Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Maria A. Magriñá
- Medical Specialties Unit From City Hall São José dos Campos, São Paulo, Brazil
| | - Carlos A. Bacino
- Department of Molecular & Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Pediatrics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Seema R. Lalani
- Department of Molecular & Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Pediatrics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Amy M. Breman
- Department of Molecular & Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Janice L. Smith
- Department of Molecular & Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Ankita Patel
- Department of Molecular & Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Rodger H. Song
- Department of Molecular & Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Weimin Bi
- Department of Molecular & Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Sau Wai Cheung
- Department of Molecular & Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Claudia M. B. Carvalho
- Department of Molecular & Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Paweł Stankiewicz
- Department of Molecular & Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
- * E-mail: (JRL); (PS)
| | - James R. Lupski
- Department of Molecular & Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Pediatrics, Baylor College of Medicine, Houston, Texas, United States of America
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas, United States of America
- Texas Children’s Hospital, Houston, Texas, United States of America
- * E-mail: (JRL); (PS)
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