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Expanding the Clinical and Mutational Spectrum of the PLP1-Related Hypomyelination of Early Myelinated Structures (HEMS). Brain Sci 2021; 11:brainsci11010093. [PMID: 33450882 PMCID: PMC7828325 DOI: 10.3390/brainsci11010093] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Revised: 01/03/2021] [Accepted: 01/11/2021] [Indexed: 11/17/2022] Open
Abstract
The PLP1 gene, located on chromosome Xq22, encodes the proteolipid protein 1 and its isoform DM20. Mutations in PLP1 cause a spectrum of white matter disorders of variable severity. Here we report on four additional HEMS patients from three families harboring three novel PLP1 mutations in exon 3B detected by targeted next-generation sequencing. Patients experienced psychomotor delay or nystagmus in the first year of age and then developed ataxic-spastic or ataxic syndrome, compatible with a phenotype of intermediate severity in the spectrum of PLP1-related disorders. Regression occurred at the beginning of the third decade of the eldest patient. Extrapyramidal involvement was rarely observed. Brain MRI confirmed the involvement of structures that physiologically myelinate early, although the pattern of abnormalities may differ depending on the age at which the study is performed. These new cases contribute to expanding the phenotypic and genotypic spectrum of HEMS. Additional studies, especially enriched by systematic functional evaluations and long-term follow-up, are welcome to better delineate the natural history of this rare hypomyelinating leukodystrophy.
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Lyahyai J, Ouled Amar Bencheikh B, Elalaoui SC, Mansouri M, Boualla L, DIonne-Laporte A, Spiegelman D, Dion PA, Cossette P, Rouleau GA, Sefiani A. Exome sequencing reveals a novel PLP1 mutation in a Moroccan family with connatal Pelizaeus-Merzbacher disease: a case report. BMC Pediatr 2018; 18:90. [PMID: 29486744 PMCID: PMC5830319 DOI: 10.1186/s12887-018-1063-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/12/2016] [Accepted: 02/15/2018] [Indexed: 11/20/2022] Open
Abstract
Background Epilepsy regroups a common and diverse set of chronic neurological disorders that are characterized by spontaneous, unprovoked, and recurrent epileptic seizures. Epilepsies have a highly heterogeneous background with a strong genetic contribution and various mode of inheritance. X-linked epilepsy usually manifests as part of a syndrome or epileptic encephalopathy. The variability of clinical manifestations of X-linked epilepsy may be attributed to several factors including the causal genetic mutation, making diagnosis, genetic counseling and treatment decisions difficult. We report the description of a Moroccan family referred to our genetic department with X-linked epileptic seizures as the only initial diagnosis. Case presentation Knowing the new contribution of Next-Generation Sequencing (NGS) for clinical investigation, and given the heterogeneity of this group of disorders we performed a Whole-Exome Sequencing (WES) analysis and co-segregation study in several members of this large family. We detected a novel pathogenic PLP1 missense mutation c.251C > A (p.Ala84Asp) allowing us to make a diagnosis of Pelizaeus-Merzbacher Disease for this family. Conclusion This report extends the spectrum of PLP1 mutations and highlights the diagnostic utility of NGS to investigate this group of heterogeneous disorders.
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Tantzer S, Sperle K, Kenaley K, Taube J, Hobson GM. Morpholino Antisense Oligomers as a Potential Therapeutic Option for the Correction of Alternative Splicing in PMD, SPG2, and HEMS. MOLECULAR THERAPY. NUCLEIC ACIDS 2018; 12:420-432. [PMID: 30195779 PMCID: PMC6036941 DOI: 10.1016/j.omtn.2018.05.019] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/22/2018] [Accepted: 05/22/2018] [Indexed: 01/10/2023]
Abstract
DNA variants of the proteolipid protein 1 gene (PLP1) that shift PLP1/DM20 alternative splicing away from the PLP1 form toward DM20 cause the allelic X-linked leukodystrophies Pelizaeus-Merzbacher disease (PMD), spastic paraplegia 2 (SPG2), and hypomyelination of early myelinating structures (HEMS). We designed a morpholino oligomer (MO-PLP) to block use of the DM20 5' splice donor site, thereby shifting alternative splicing toward the PLP1 5' splice site. Treatment of an immature oligodendrocyte cell line with MO-PLP significantly shifted alternative splicing toward PLP1 expression from the endogenous gene and from transfected human minigene splicing constructs harboring patient variants known to reduce the amount of the PLP1 spliced product. Additionally, a single intracerebroventricular injection of MO-PLP into the brains of neonatal mice, carrying a deletion of an intronic splicing enhancer identified in a PMD patient that reduces the Plp1 spliced form, corrected alternative splicing at both RNA and protein levels in the CNS. The effect lasted to post-natal day 90, well beyond the early post-natal spike in myelination and PLP production. Further, the single injection produced a sustained reduction of inflammatory markers in the brains of the mice. Our results suggest that morpholino oligomers have therapeutic potential for the treatment of PMD, SPG2, and HEMS.
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Affiliation(s)
- Stephanie Tantzer
- Nemours Biomedical Research, Alfred I. duPont Hospital for Children, Wilmington, DE 19803, USA
| | - Karen Sperle
- Nemours Biomedical Research, Alfred I. duPont Hospital for Children, Wilmington, DE 19803, USA
| | - Kaitlin Kenaley
- Nemours Biomedical Research, Alfred I. duPont Hospital for Children, Wilmington, DE 19803, USA; Department of Pediatrics/Neonatology, Christiana Care Health System, Newark, DE 19713, USA
| | - Jennifer Taube
- Nemours Biomedical Research, Alfred I. duPont Hospital for Children, Wilmington, DE 19803, USA
| | - Grace M Hobson
- Nemours Biomedical Research, Alfred I. duPont Hospital for Children, Wilmington, DE 19803, USA; Department of Biological Sciences, University of Delaware, Newark, DE 19716, USA; Department of Pediatrics, Jefferson Medical College, Thomas Jefferson University, Philadelphia, PA 19107, USA.
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Margraf RL, Durtschi J, Krock B, Newcomb TM, Bonkowsky JL, Voelkerding KV, Bayrak-Toydemir P, Lutz RE, Swoboda KJ. Novel PLP1 Mutations Identified With Next-Generation Sequencing Expand the Spectrum of PLP1-Associated Leukodystrophy Clinical Phenotypes. Child Neurol Open 2018; 5:2329048X18789282. [PMID: 30046645 PMCID: PMC6056774 DOI: 10.1177/2329048x18789282] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2018] [Accepted: 06/12/2018] [Indexed: 11/30/2022] Open
Abstract
Next-generation sequencing was performed for 2 families with an undiagnosed neurologic disease. Analysis revealed X-linked mutations in the proteolipid protein 1 (PLP1) gene, which is associated with X-linked Pelizaeus-Merzbacher disease and Spastic Paraplegia type 2. In family A, the novel PLP1 missense mutation c.617T>A (p.M206K) was hemizygous in the 2 affected male children and heterozygous in the mother. In family B, the novel de novoPLP1 frameshift mutation c.359_369del (p.G120fs) was hemizygous in the affected male child. Although PLP1 mutations have been reported to cause an increasingly wide range of phenotypes inclusive of the dystonia, spastic paraparesis, motor neuronopathy, and leukodystrophy observed in our patients, atypical features included the cerebrospinal fluid deficiency of neurotransmitter and pterin metabolites and the delayed appearance of myelin abnormalities on neuroimaging studies. Next-generation sequencing studies provided a diagnosis for these families with complex leukodystrophy disease phenotypes, which expanded the spectrum of PLP1-associated leukodystrophy clinical phenotypes.
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Affiliation(s)
- Rebecca L Margraf
- ARUP Institute for Clinical and Experimental Pathology, ARUP Laboratories, Salt Lake City, UT, USA
| | - Jacob Durtschi
- ARUP Institute for Clinical and Experimental Pathology, ARUP Laboratories, Salt Lake City, UT, USA
| | - Bryan Krock
- ARUP Institute for Clinical and Experimental Pathology, ARUP Laboratories, Salt Lake City, UT, USA
- Department of Pathology, University of Utah School of Medicine, Salt Lake City, UT, USA
| | - Tara M Newcomb
- Pediatric Motor Disorders Research Program, Department of Neurology, University of Utah School of Medicine, Salt Lake City, UT, USA
| | - Joshua L Bonkowsky
- Division of Pediatric Neurology, Department of Pediatrics, University of Utah School of Medicine, Salt Lake City, UT, USA
| | - Karl V Voelkerding
- ARUP Institute for Clinical and Experimental Pathology, ARUP Laboratories, Salt Lake City, UT, USA
- Department of Pathology, University of Utah School of Medicine, Salt Lake City, UT, USA
| | - Pinar Bayrak-Toydemir
- ARUP Institute for Clinical and Experimental Pathology, ARUP Laboratories, Salt Lake City, UT, USA
- Department of Pathology, University of Utah School of Medicine, Salt Lake City, UT, USA
| | - Richard E Lutz
- Department of Endocrinology, University of Nebraska Medical Center, Omaha, NE, USA
- Department of Genetics, University of Nebraska Medical Center, Omaha, NE, USA
| | - Kathryn J Swoboda
- Pediatric Motor Disorders Research Program, Department of Neurology, University of Utah School of Medicine, Salt Lake City, UT, USA
- Division of Pediatric Neurology, Department of Pediatrics, University of Utah School of Medicine, Salt Lake City, UT, USA
- Department of Neurology, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA
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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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The magnetic resonance imaging spectrum of Pelizaeus-Merzbacher disease: A multicenter study of 19 patients. Brain Dev 2016; 38:571-80. [PMID: 26774704 DOI: 10.1016/j.braindev.2015.12.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/26/2015] [Revised: 12/09/2015] [Accepted: 12/10/2015] [Indexed: 11/21/2022]
Abstract
PURPOSE We retrospectively evaluated the imaging spectrum of Pelizaeus-Merzbacher disease (PMD) in correlation with the clinical course and genetic abnormality. METHODS We collected the magnetic resonance imaging (MRI) findings of 19 genetically proven PMD patients (all males, aged 0-29years old) using our integrated web-based MRI data collection system from 14 hospitals. The patterns of hypomyelination were determined mainly by the signals of the cerebrum, corticospinal tract, and brainstem on T2-weighted images (T2WI). We assessed the degree of myelination age on T1-weighted images (T1WI) and T2WI independently, and we evaluated cerebellar and callosal atrophy. The clinical severity and genetic abnormalities (causal mutations of the proteolipid protein gene PLP1) were analyzed together with the imaging findings. RESULTS The clinical stage tended to be more severe when the whole brainstem, or corticospinal tract in the internal capsule showed abnormally high intensity on T2WI. Diffuse T2-high signal of brainstem was observed only in the patients with PLP1 point mutation. Myelination age "before birth" on T1WI is a second manifestation correlated with the clinically severe phenotypes. On the other hand, eight patients whose myelination ages were > 4months on T1WI were associated with mild clinical phenotypes. Four of them showed almost complete myelination on T1WI with a discrepancy in myelination age between T1WI and T2WI. A random and patchy pattern of myelination on T2WI was noted in one patient with PLP1 point mutation. Advanced myelination was observed in three of the seven followed-up patients. Four patients had atrophy of the cerebellum, and 17 patients had atrophy of the corpus callosum. CONCLUSION Our multicenter study has demonstrated a wide variety of imaging findings of PMD. Signal intensity of brainstem and corticospinal tract of internal capsule would be the points to presume clinical severity in PMD patients. The spectrum of MRI findings should be kept in mind to diagnose PMD and to differentiate from other demyelinating leukodystrophies.
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Yu Y, Li Y, Zhang Y. Yeast Two-Hybrid Screening for Proteins that Interact with the Extracellular Domain of Amyloid Precursor Protein. Neurosci Bull 2016; 32:171-6. [PMID: 26960425 DOI: 10.1007/s12264-016-0021-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2015] [Accepted: 12/11/2015] [Indexed: 12/25/2022] Open
Abstract
Alzheimer's disease (AD) is a neurodegenerative disorder in which amyloid β plaques are a pathological characteristic. Little is known about the physiological functions of amyloid β precursor protein (APP). Based on its structure as a type I transmembrane protein, it has been proposed that APP might be a receptor, but so far, no ligand has been reported. In the present study, 9 proteins binding to the extracellular domain of APP were identified using a yeast two-hybrid system. After confirming the interactions in the mammalian system, mutated PLP1, members of the FLRT protein family, and KCTD16 were shown to interact with APP. These proteins have been reported to be involved in Pelizaeus-Merzbacher disease (PMD) and axon guidance. Therefore, our results shed light on the mechanisms of physiological function of APP in AD, PMD, and axon guidance.
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Affiliation(s)
- You Yu
- State Key Laboratory of Membrane Biology, College of Life Sciences, PKU-IDG/McGovern Institute for Brain Research, Peking University, Beijing, 100871, China
| | - Yinan Li
- State Key Laboratory of Membrane Biology, College of Life Sciences, PKU-IDG/McGovern Institute for Brain Research, Peking University, Beijing, 100871, China
| | - Yan Zhang
- State Key Laboratory of Membrane Biology, College of Life Sciences, PKU-IDG/McGovern Institute for Brain Research, Peking University, Beijing, 100871, China.
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Kevelam SH, Taube JR, van Spaendonk RML, Bertini E, Sperle K, Tarnopolsky M, Tonduti D, Valente EM, Travaglini L, Sistermans EA, Bernard G, Catsman-Berrevoets CE, van Karnebeek CDM, Østergaard JR, Friederich RL, Fawzi Elsaid M, Schieving JH, Tarailo-Graovac M, Orcesi S, Steenweg ME, van Berkel CGM, Waisfisz Q, Abbink TEM, van der Knaap MS, Hobson GM, Wolf NI. Altered PLP1 splicing causes hypomyelination of early myelinating structures. Ann Clin Transl Neurol 2015; 2:648-61. [PMID: 26125040 PMCID: PMC4479525 DOI: 10.1002/acn3.203] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2015] [Revised: 03/03/2015] [Accepted: 03/12/2015] [Indexed: 12/19/2022] Open
Abstract
Objective The objective of this study was to investigate the genetic etiology of the X-linked disorder “Hypomyelination of Early Myelinating Structures” (HEMS). Methods We included 16 patients from 10 families diagnosed with HEMS by brain MRI criteria. Exome sequencing was used to search for causal mutations. In silico analysis of effects of the mutations on splicing and RNA folding was performed. In vitro gene splicing was examined in RNA from patients’ fibroblasts and an immortalized immature oligodendrocyte cell line after transfection with mutant minigene splicing constructs. Results All patients had unusual hemizygous mutations of PLP1 located in exon 3B (one deletion, one missense and two silent), which is spliced out in isoform DM20, or in intron 3 (five mutations). The deletion led to truncation of PLP1, but not DM20. Four mutations were predicted to affect PLP1/DM20 alternative splicing by creating exonic splicing silencer motifs or new splice donor sites or by affecting the local RNA structure of the PLP1 splice donor site. Four deep intronic mutations were predicted to destabilize a long-distance interaction structure in the secondary PLP1 RNA fragment involved in regulating PLP1/DM20 alternative splicing. Splicing studies in fibroblasts and transfected cells confirmed a decreased PLP1/DM20 ratio. Interpretation Brain structures that normally myelinate early are poorly myelinated in HEMS, while they are the best myelinated structures in Pelizaeus–Merzbacher disease, also caused by PLP1 alterations. Our data extend the phenotypic spectrum of PLP1-related disorders indicating that normal PLP1/DM20 alternative splicing is essential for early myelination and support the need to include intron 3 in diagnostic sequencing.
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Affiliation(s)
- Sietske H Kevelam
- Department of Child Neurology, VU University Medical Center Amsterdam, The Netherlands ; Neuroscience Campus Amsterdam, VU University Amsterdam, The Netherlands
| | - Jennifer R Taube
- Nemours Biomedical Research, Alfred I. duPont Hospital for Children Wilmington, Delaware
| | | | - Enrico Bertini
- Unit for Neuromuscular and Neurodegenerative Diseases, Laboratory of Molecular Medicine, Bambino Gesu' Children's Research Hospital, IRCCS Rome, Italy
| | - Karen Sperle
- Nemours Biomedical Research, Alfred I. duPont Hospital for Children Wilmington, Delaware
| | - Mark Tarnopolsky
- Department of Pediatrics, McMaster Children's Hospital Hamilton, Ontario, Canada
| | - Davide Tonduti
- Child Neuropsychiatry Unit, Department of Brain and Behavioral Sciences, University of Pavia Pavia, Italy
| | - Enza Maria Valente
- Department of Medicine and Surgery, University of Salerno Salerno, Italy ; CSS-Mendel Institute, IRCCS Casa Sollievo della Sofferenza San Giovanni Rotondo, Italy
| | - Lorena Travaglini
- Unit for Neuromuscular and Neurodegenerative Diseases, Laboratory of Molecular Medicine, Bambino Gesu' Children's Research Hospital, IRCCS Rome, Italy
| | - Erik A Sistermans
- Department of Clinical Genetics, VU University Medical Center Amsterdam, The Netherlands
| | - Geneviève Bernard
- Division of Pediatric Neurology, Departments of Pediatrics, Neurology and Neurosurgery, Montreal Children's Hospital, McGill University Health Center Montreal, Quebec, Canada
| | - Coriene E Catsman-Berrevoets
- Department of Pediatric Neurology, Erasmus University Hospital - Sophia Children's Hospital Rotterdam, The Netherlands
| | - Clara D M van Karnebeek
- Division of Biochemical Diseases, Department of Pediatrics, BC Children's Hospital, Centre for Molecular Medicine and Therapeutics, University of British Columbia Vancouver, Canada
| | - John R Østergaard
- Centre for Rare diseases, Department of Paediatrics, Aarhus University Hospital Aarhus, Denmark
| | - Richard L Friederich
- Department of Child Neurology, Kaiser Permanente Pediatric Specialties Roseville, California
| | | | - Jolanda H Schieving
- Department of Child Neurology, Radboud University Medical Center Nijmegen, The Netherlands
| | - Maja Tarailo-Graovac
- Department of Medical Genetics, University of British Colombia Vancouver, Canada
| | - Simona Orcesi
- Child Neurology and Psychiatry Unit, C. Mondino National Neurological Institute Pavia, Italy
| | - Marjan E Steenweg
- Department of Child Neurology, VU University Medical Center Amsterdam, The Netherlands ; Neuroscience Campus Amsterdam, VU University Amsterdam, The Netherlands
| | - Carola G M van Berkel
- Department of Child Neurology, VU University Medical Center Amsterdam, The Netherlands
| | - Quinten Waisfisz
- Department of Clinical Genetics, VU University Medical Center Amsterdam, The Netherlands
| | - Truus E M Abbink
- Department of Child Neurology, VU University Medical Center Amsterdam, The Netherlands ; Neuroscience Campus Amsterdam, VU University Amsterdam, The Netherlands
| | - Marjo S van der Knaap
- Department of Child Neurology, VU University Medical Center Amsterdam, The Netherlands ; Neuroscience Campus Amsterdam, VU University Amsterdam, The Netherlands ; Department of Functional Genomics, Center for Neurogenomics and Cognitive Research, VU University Amsterdam, The Netherlands
| | - Grace M Hobson
- Nemours Biomedical Research, Alfred I. duPont Hospital for Children Wilmington, Delaware ; Department of Biological Sciences, University of Delaware Newark, Delaware ; Department of Pediatrics, Jefferson Medical College, Thomas Jefferson University Philadelphia, Pennsylvania
| | - Nicole I Wolf
- Department of Child Neurology, VU University Medical Center Amsterdam, The Netherlands ; Neuroscience Campus Amsterdam, VU University Amsterdam, The Netherlands
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A novel PLP1 frameshift mutation causing a milder form of Pelizaeus-Merzbacher disease. Brain Dev 2015; 37:455-8. [PMID: 25043250 DOI: 10.1016/j.braindev.2014.06.011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/16/2014] [Revised: 06/21/2014] [Accepted: 06/25/2014] [Indexed: 01/19/2023]
Abstract
BACKGROUND Pelizaeus-Merzbacher disease (PMD), a hypomyelinating leukodystrophy, and the related but less severe allelic spastic paraplegia 2 (SPG2) are caused by mutations in the proteolipid protein 1 (PLP1) gene. Magnetic resonance imaging (MRI) is pivotal for diagnosing these disorders. The severity of PMD/SPG2 varies, and for a milder form of PMD, there have been some reports of near-normal findings in T1-weighted images but abnormal findings in T2-weighted images. PATIENT We report the case of a 5-year-old boy diagnosed with a milder form of PMD caused by a novel PLP1 mutation in exon 3: c.300delC (p.I100IfsX13). He had delayed development from several months of age and was able to walk with support at 19 months in spite of the spasticity in his lower extremities. Hypomyelination was noted at 12 months by brain MRI. Motor nerve conduction studies showed decreased velocities with reduced amplitudes. Follow-up MRI at 1-year intervals from 18 months until 55 months of age showed gradual myelination progress. DISCUSSION The single nucleotide deletion identified in this patient can cause a frameshift and premature termination of PLP1. Via the nonsense-mediated mRNA decay mechanism of this mutation will result in loss-of-function, leading to a milder form of PMD. The present case is compatible with previously reported cases of milder form of PMD. We incidentally identified progressive myelination in this patient by T1-weighted images obtained by serial MRI. This finding adds to our understanding of the pathological stages of a milder form of PMD.
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Krishna SH, McKinney AM, Lucato LT. Congenital Genetic Inborn Errors of Metabolism Presenting as an Adult or Persisting Into Adulthood: Neuroimaging in the More Common or Recognizable Disorders. Semin Ultrasound CT MR 2014; 35:160-91. [DOI: 10.1053/j.sult.2013.10.008] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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Yamamoto T, Shimojima K. Pelizaeus-Merzbacher disease as a chromosomal disorder. Congenit Anom (Kyoto) 2013; 53:3-8. [PMID: 23480352 DOI: 10.1111/cga.12005] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/21/2012] [Accepted: 11/04/2012] [Indexed: 12/29/2022]
Abstract
Pelizaeus-Merzbacher disease (PMD) is a congenital hypomyelination disorder caused by alterations affecting the proteolipid protein 1 gene (PLP1) located on Xq22.2. Generally, patients with PLP1 missense mutations show the most severe form of PMD (connatal form); however, two-thirds of patients with PMD carry PLP1 duplications and present typical manifestations of the disorder, recognized as the classical form. Other rare PLP1 abnormalities have been also identified, including X-chromosome translocations, triplications, and a partial duplication, all involving PLP1. The genomic structure of the distal end of the PLP1 locus, characterized by repeated genomic segments, contributes to the chromosomal rearrangements around PLP1 and the manifestation of PMD. Thus, PMD is recognized as a chromosomal disorder.
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Affiliation(s)
- Toshiyuki Yamamoto
- Institute for Integrated Medical Sciences, Tokyo Women's Medical University, Tokyo, Japan.
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12
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An autopsy case of adult-onset hereditary spastic paraplegia type 2 with a novel mutation in exon 7 of the proteolipid protein 1 gene. Acta Neuropathol 2011; 122:775-81. [PMID: 22101368 DOI: 10.1007/s00401-011-0916-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2011] [Revised: 11/09/2011] [Accepted: 11/12/2011] [Indexed: 01/15/2023]
Abstract
We report an autopsy case of rare adult-onset spastic paraplegia type 2 (SPG2) with a novel missense mutation in exon 7 of the proteolipid protein 1 gene (PLP1). The patient was a 67-year-old man whose elder brother had died of a similar disease with onset in his 40s. Thirty-three years before death at the age of 35, he noticed difficulty in walking. He gradually became abasic over a period of 6 years. He also developed progressive dementia and eventually became bed-ridden by 28 years after onset. At autopsy, gross inspection revealed diffuse, moderate atrophy of the cerebrum with a dilated ventricular system and softening of the white matter throughout the central nervous system (CNS). Histopathologically, the CNS showed widespread myelin pallor in the white matter. By contrast, the gray matter and peripheral nerves were well preserved. Some white matter tracts, including the corticospinal tracts, were preferentially affected, and severe axonal degeneration was observed in these tracts. Genetic analysis revealed a novel mutation, p.Tyr263Cys, in exon 7 of PLP1. This case represents an adult-onset SPG2 patient with one of the oldest ages of onset reported to date. The late onset and long clinical course suggest that this novel mutation does not affect the maturation of oligodendrocytes, but is related to insufficient maintenance of myelin.
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