1
|
Thakkar RN, Patel D, Kioutchoukova IP, Al-Bahou R, Reddy P, Foster DT, Lucke-Wold B. Leukodystrophy Imaging: Insights for Diagnostic Dilemmas. Med Sci (Basel) 2024; 12:7. [PMID: 38390857 PMCID: PMC10885080 DOI: 10.3390/medsci12010007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Revised: 12/09/2023] [Accepted: 12/13/2023] [Indexed: 02/24/2024] Open
Abstract
Leukodystrophies, a group of rare demyelinating disorders, mainly affect the CNS. Clinical presentation of different types of leukodystrophies can be nonspecific, and thus, imaging techniques like MRI can be used for a more definitive diagnosis. These diseases are characterized as cerebral lesions with characteristic demyelinating patterns which can be used as differentiating tools. In this review, we talk about these MRI study findings for each leukodystrophy, associated genetics, blood work that can help in differentiation, emerging diagnostics, and a follow-up imaging strategy. The leukodystrophies discussed in this paper include X-linked adrenoleukodystrophy, metachromatic leukodystrophy, Krabbe's disease, Pelizaeus-Merzbacher disease, Alexander's disease, Canavan disease, and Aicardi-Goutières Syndrome.
Collapse
Affiliation(s)
- Rajvi N. Thakkar
- College of Medicine, University of Florida, Gainesville, FL 32610, USA
| | - Drashti Patel
- College of Medicine, University of Florida, Gainesville, FL 32610, USA
| | | | - Raja Al-Bahou
- College of Medicine, University of Florida, Gainesville, FL 32610, USA
| | - Pranith Reddy
- College of Medicine, Florida Atlantic University, Boca Raton, FL 33431, USA
| | - Devon T. Foster
- College of Medicine, Florida International University, Miami, FL 33199, USA
| | - Brandon Lucke-Wold
- Department of Neurosurgery, University of Florida, 1600 SW Archer Rd., Gainesville, FL 32610, USA
| |
Collapse
|
2
|
Trepanier AM, Aguilar S, Kamholz J, Laukka JJ. The natural history of Pelizaeus-Merzbacher disease caused by PLP1 duplication: A multiyear case series. Clin Case Rep 2023; 11:e7814. [PMID: 37636890 PMCID: PMC10457477 DOI: 10.1002/ccr3.7814] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2023] [Revised: 07/03/2023] [Accepted: 07/07/2023] [Indexed: 08/29/2023] Open
Abstract
This study aimed to characterize the clinical features, developmental milestones, and the natural history of Pelizaeus-Merzbacher disease (PMD) associated with PLP1 gene duplications. The study examined 16 PMD Patients ranging in age from 7 to 48 years, who had a documented PLP1 gene duplication. The study examined and analyzed the medical and developmental histories of the subjects utilizing a combination of resources that included medical history questionnaires, medical record reviews, and a 31-point functional disability scale that had been previously validated. The data extracted from the medical records and questionnaires for analysis included information related to medical and developmental histories, level of ambulation and cognition, and degree of functional disability. The summation of findings among the study population demonstrated that the presenting symptoms, developmental milestones achieved, and progression of symptoms reported are consistent with many previous studies of patients with PLP1 duplications. All patients exhibited onset within the first year of life, with nystagmus predominating as the first symptom noticed. All patients exhibited delays in both motor and language development; however, many individuals were able to meet several developmental milestones. They exhibited some degree of continued motor impairment with none having the ability to walk independently. All patients were able to complete at least some of the cognition achievements and although not all were verbal, a number were able to use communication devices to complete these tasks. A critical tool of the study was the functional disability scale which provided a major advantage in helping quantify the clinical course of PMD, and for several, we were able to gather this information at more than one point in time. These reported findings in our cohort contribute important insight into the clinical heterogeneity and potential underlying mechanisms that define the molecular pathogenesis of the disease. This is one of only a small number of natural history studies examining the clinical course of a cohort of patients with PLP1 duplications within the context of a validated functional disability scoring system. This study is unique in that it is limited to subjects with PLP1 gene duplications. This study demonstrated many commonalities to other studies that have characterized the features of PMD and other PLP1-related disorders but also provide significant new insights into the evolving story that marks the natural history.
Collapse
Affiliation(s)
- Angela M. Trepanier
- Center for Molecular Medicine and GeneticsWayne State University School of MedicineDetroitMichiganUSA
| | - Sienna Aguilar
- Center for Molecular Medicine and GeneticsWayne State University School of MedicineDetroitMichiganUSA
- Invitae, Inc.San FranciscoCaliforniaUSA
| | - John Kamholz
- Center for Molecular Medicine and GeneticsWayne State University School of MedicineDetroitMichiganUSA
- Department of NeurologyUniversity of Iowa Carver College of MedicineIowa CityIowaUSA
| | - Jeremy J. Laukka
- Department of Medical EducationUniversity of Toledo College of Medicine & Life SciencesToledoOhioUSA
- Department of NeurologyUniversity of Toledo College of Medicine & Life SciencesToledoOhioUSA
| |
Collapse
|
3
|
Moore KM, Wolf NI, Hobson G, Bowyer K, McSherry J, Hartin G, Wilde C, Shapiro S, Frank J, Manley D, Junge C. Pelizaeus-Merzbacher Disease: A Caregiver Assessment of Disease Impact. J Child Neurol 2023; 38:78-84. [PMID: 36744386 DOI: 10.1177/08830738231152658] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Pelizaeus-Merzbacher disease is a rare X-linked leukodystrophy accompanied by central nervous system hypomyelination with a spectrum of clinical phenotypes. This is the first survey of caregivers of individuals with Pelizaeus-Merzbacher disease to investigate the presenting symptoms, path to diagnosis, identity and impact of most bothersome symptoms, and needs that future treatment should address. One hundred participants completed the survey. Results from this survey demonstrate that the majority of Pelizaeus-Merzbacher disease symptoms manifest before 2 years of age and commonly include deficits in gross and fine motor skills, speech, and communication. Caregivers rated difficulty crawling, standing, or walking as the most bothersome symptoms due to Pelizaeus-Merzbacher disease, with constipation and difficulty with sleep, manual dexterity, and speech and communication rated nearly as high. The most important treatment goals for caregivers were improved mobility and communication. The survey findings present a caregiver perspective of the impact of symptoms in Pelizaeus-Merzbacher disease and provide helpful guidance to affected families, physicians, and drug developers on the often-long path to diagnosis and the unmet medical needs of this patient population.
Collapse
Affiliation(s)
| | - Nicole I Wolf
- Department of Child Neurology, Amsterdam Leukodystrophy Centre, Emma Children's Hospital, Amsterdam University Medical Centres, Vrije Universiteit, Amsterdam, Netherlands.,Amsterdam Neuroscience, Cellular & Molecular Mechanisms, Amsterdam, The Netherlands
| | - Grace Hobson
- Department of Research, Nemours Alfred I duPont Hospital for Children, Wilmington, DE, USA
| | | | | | | | | | | | - Jason Frank
- ClarityCo Strategic Group, West Chester, PA, USA
| | | | | |
Collapse
|
4
|
Khalaf G, Mattern C, Begou M, Boespflug-Tanguy O, Massaad C, Massaad-Massade L. Mutation of Proteolipid Protein 1 Gene: From Severe Hypomyelinating Leukodystrophy to Inherited Spastic Paraplegia. Biomedicines 2022; 10:biomedicines10071709. [PMID: 35885014 PMCID: PMC9313024 DOI: 10.3390/biomedicines10071709] [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: 06/10/2022] [Revised: 07/06/2022] [Accepted: 07/12/2022] [Indexed: 01/17/2023] Open
Abstract
Pelizaeus–Merzbacher Disease (PMD) is an inherited leukodystrophy affecting the central nervous system (CNS)—a rare disorder that especially concerns males. Its estimated prevalence is 1.45–1.9 per 100,000 individuals in the general population. Patients affected by PMD exhibit a drastic reduction or absence of myelin sheaths in the white matter areas of the CNS. The Proteolipid Protein 1 (PLP1) gene encodes a transmembrane proteolipid protein. PLP1 is the major protein of myelin, and it plays a key role in the compaction, stabilization, and maintenance of myelin sheaths. Its function is predominant in oligodendrocyte development and axonal survival. Mutations in the PLP1 gene cause the development of a wide continuum spectrum of leukopathies from the most severe form of PMD for whom patients exhibit severe CNS hypomyelination to the relatively mild late-onset type 2 spastic paraplegia, leading to the concept of PLP1-related disorders. The genetic diversity and the biochemical complexity, along with other aspects of PMD, are discussed to reveal the obstacles that hinder the development of treatments. This review aims to provide a clinical and mechanistic overview of this spectrum of rare diseases.
Collapse
Affiliation(s)
- Guy Khalaf
- U1195 Diseases and Hormones of the Nervous System, INSERM and Université Paris-Saclay, 94276 Le Kremlin-Bicêtre, France;
| | | | - Mélina Begou
- Neuro-Dol, CNRS, Inserm, Université Clermont Auvergne, 63000 Clermont-Ferrand, France;
| | - Odile Boespflug-Tanguy
- UMR 1141, INSERM, NeuroDiderot Université Paris Cité and APH-P, Neuropédiatrie, French Reference Center for Leukodystrophies, LEUKOFRANCE, Hôpital Robert Debré, 75019 Paris, France;
| | - Charbel Massaad
- UMRS 1124, INSERM, Université Paris Cité, 75006 Paris, France
- Correspondence: (C.M.); (L.M.-M.);Tel.: +33-1-49-59-18-30 (L.M.-M.)
| | - Liliane Massaad-Massade
- U1195 Diseases and Hormones of the Nervous System, INSERM and Université Paris-Saclay, 94276 Le Kremlin-Bicêtre, France;
- Correspondence: (C.M.); (L.M.-M.);Tel.: +33-1-49-59-18-30 (L.M.-M.)
| |
Collapse
|
5
|
Duan R, Li L, Yan H, He M, Gao K, Xing S, Ji H, Wang J, Cao B, Li D, Xie H, Zhao S, Wu Y, Jiang Y, Xiao J, Gu Q, Li M, Zheng X, Chen L, Wang J. Novel Insight into the Potential Pathogenicity of Mitochondrial Dysfunction Resulting from PLP1 Duplication Mutations in Patients with Pelizaeus-Merzbacher Disease. Neuroscience 2021; 476:60-71. [PMID: 34506833 DOI: 10.1016/j.neuroscience.2021.08.029] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2021] [Revised: 08/25/2021] [Accepted: 08/26/2021] [Indexed: 11/17/2022]
Abstract
Among the hypomyelinating leukodystrophies, Pelizaeus-Merzbacher disease (PMD) is a representative disorder. The disease is caused by different types of PLP1 mutations, among which PLP1 duplication accounts for ∼70% of the mutations. Previous studies have shown that PLP1 duplications lead to PLP1 retention in the endoplasmic reticulum (ER); in parallel, recent studies have demonstrated that PLP1 duplication can also lead to mitochondrial dysfunction. As such, the respective roles and interactions of the ER and mitochondria in the pathogenesis of PLP1 duplication are not clear. In both PLP1 patients' and healthy fibroblasts, we measured mitochondrial respiration with a Seahorse XF Extracellular Analyzer and examined the interactions between the ER and mitochondria with super-resolution microscopy (spinning-disc pinhole-based structured illumination microscopy, SD-SIM). For the first time, we demonstrated that PLP1 duplication mutants had closer ER-mitochondrion interfaces mediated through structural and morphological changes in both the ER and mitochondria-associated membranes (MAMs). These changes in both the ER and mitochondria then led to mitochondrial dysfunction, as reported previously. This work highlights the roles of MAMs in bridging PLP1 expression in the ER and pathogenic dysfunction in mitochondria, providing novel insight into the pathogenicity of mitochondrial dysfunction resulting from PLP1 duplication. These findings suggest that interactions between the ER and mitochondria may underlie pathogenic mechanisms of hypomyelinating leukodystrophies diseases at the organelle level.
Collapse
Affiliation(s)
- Ruoyu Duan
- Department of Pediatrics, Peking University First Hospital, Beijing 100034, China
| | - Liuju Li
- State Key Laboratory of Membrane Biology, Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Institute of Molecular Medicine, School of Future Technology, Peking University, Beijing 100871, China
| | - Huifang Yan
- Department of Pediatrics, Peking University First Hospital, Beijing 100034, China
| | - Miao He
- Institute for Brain Research and Rehabilitation (IBRR), Guangdong Key Laboratory of Mental Health and Cognitive Science, South China Normal University, Guangzhou, China
| | - Kai Gao
- Department of Pediatrics, Peking University First Hospital, Beijing 100034, China
| | - Shijia Xing
- State Key Laboratory of Membrane Biology, Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Institute of Molecular Medicine, School of Future Technology, Peking University, Beijing 100871, China
| | - Haoran Ji
- Department of Pediatrics, Peking University First Hospital, Beijing 100034, China
| | - Jianyong Wang
- School of Software and Microelectronics, Peking University, Beijing 100871, China
| | - Binbin Cao
- Department of Pediatrics, Peking University First Hospital, Beijing 100034, China
| | - Dongxiao Li
- Department of Pediatrics, Peking University First Hospital, Beijing 100034, China
| | - Han Xie
- Department of Pediatrics, Peking University First Hospital, Beijing 100034, China
| | - Shiqun Zhao
- State Key Laboratory of Membrane Biology, Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Institute of Molecular Medicine, School of Future Technology, Peking University, Beijing 100871, China
| | - Ye Wu
- Department of Pediatrics, Peking University First Hospital, Beijing 100034, China
| | - Yuwu Jiang
- Department of Pediatrics, Peking University First Hospital, Beijing 100034, China
| | - Jiangxi Xiao
- Department of Radiology, Peking University First Hospital, Beijing, China
| | - Qiang Gu
- Department of Pediatrics, Peking University First Hospital, Beijing 100034, China
| | - Ming Li
- Department of Pediatrics, Peking University First Hospital, Beijing 100034, China
| | - Xiaolu Zheng
- State Key Laboratory of Membrane Biology, Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Institute of Molecular Medicine, School of Future Technology, Peking University, Beijing 100871, China; Institute of Biomedical Engineering, Beijing Institute of Collaborative Innovation (BICI), Beijing 100094, China.
| | - Liangyi Chen
- State Key Laboratory of Membrane Biology, Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Institute of Molecular Medicine, School of Future Technology, Peking University, Beijing 100871, China; National Biomedical Imaging Center, Peking University, Beijing 100871, China; PKU-IDG/McGovern Institute for Brain Research, Beijing 100871, China.
| | - Jingmin Wang
- Department of Pediatrics, Peking University First Hospital, Beijing 100034, China; Key Laboratory for Neuroscience, Ministry of Education/National Health and Family Planning Commission, Peking University, Beijing 100034, China; Beijing Key Laboratory of Molecular Diagnosis and Study on Pediatric Genetic Diseases, Peking University First Hospital, Beijing 100083, China.
| |
Collapse
|
6
|
Gruenenfelder FI, McLaughlin M, Griffiths IR, Garbern J, Thomson G, Kuzman P, Barrie JA, McCulloch ML, Penderis J, Stassart R, Nave KA, Edgar JM. Neural stem cells restore myelin in a demyelinating model of Pelizaeus-Merzbacher disease. Brain 2020; 143:1383-1399. [PMID: 32419025 PMCID: PMC7462093 DOI: 10.1093/brain/awaa080] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Revised: 01/20/2020] [Accepted: 02/05/2020] [Indexed: 12/13/2022] Open
Abstract
Pelizaeus-Merzbacher disease is a fatal X-linked leukodystrophy caused by mutations in the PLP1 gene, which is expressed in the CNS by oligodendrocytes. Disease onset, symptoms and mortality span a broad spectrum depending on the nature of the mutation and thus the degree of CNS hypomyelination. In the absence of an effective treatment, direct cell transplantation into the CNS to restore myelin has been tested in animal models of severe forms of the disease with failure of developmental myelination, and more recently, in severely affected patients with early disease onset due to point mutations in the PLP1 gene, and absence of myelin by MRI. In patients with a PLP1 duplication mutation, the most common cause of Pelizaeus-Merzbacher disease, the pathology is poorly defined because of a paucity of autopsy material. To address this, we examined two elderly patients with duplication of PLP1 in whom the overall syndrome, including end-stage pathology, indicated a complex disease involving dysmyelination, demyelination and axonal degeneration. Using the corresponding Plp1 transgenic mouse model, we then tested the capacity of transplanted neural stem cells to restore myelin in the context of PLP overexpression. Although developmental myelination and axonal coverage by endogenous oligodendrocytes was extensive, as assessed using electron microscopy (n = 3 at each of four end points) and immunostaining (n = 3 at each of four end points), wild-type neural precursors, transplanted into the brains of the newborn mutants, were able to effectively compete and replace the defective myelin (n = 2 at each of four end points). These data demonstrate the potential of neural stem cell therapies to restore normal myelination and protect axons in patients with PLP1 gene duplication mutation and further, provide proof of principle for the benefits of stem cell transplantation for other fatal leukodystrophies with 'normal' developmental myelination.
Collapse
Affiliation(s)
- Fredrik I Gruenenfelder
- School of Veterinary Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, G12 8TA, UK
| | - Mark McLaughlin
- School of Veterinary Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, G12 8TA, UK
| | - Ian R Griffiths
- School of Veterinary Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, G12 8TA, UK
| | - James Garbern
- Department of Neurology and Center for Molecular Medicine and Genetics, Wayne State University, Detroit, MI 48201, USA
| | - Gemma Thomson
- School of Veterinary Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, G12 8TA, UK
| | - Peter Kuzman
- Department of Neuropathology, University Clinic Leipzig, D-04103 Leipzig, Germany
| | - Jennifer A Barrie
- School of Veterinary Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, G12 8TA, UK.,Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, G12 8TA, UK
| | - Maj-Lis McCulloch
- School of Veterinary Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, G12 8TA, UK
| | - Jacques Penderis
- School of Veterinary Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, G12 8TA, UK
| | - Ruth Stassart
- Department of Neuropathology, University Clinic Leipzig, D-04103 Leipzig, Germany
| | - Klaus-Armin Nave
- Max Planck Institute for Experimental Medicine, D-37075 Goettingen, Germany
| | - Julia M Edgar
- School of Veterinary Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, G12 8TA, UK.,Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, G12 8TA, UK.,Max Planck Institute for Experimental Medicine, D-37075 Goettingen, Germany
| |
Collapse
|
7
|
Analyses of breakpoint junctions of complex genomic rearrangements comprising multiple consecutive microdeletions by nanopore sequencing. J Hum Genet 2020; 65:735-741. [PMID: 32355308 DOI: 10.1038/s10038-020-0762-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2019] [Revised: 04/01/2020] [Accepted: 04/04/2020] [Indexed: 12/19/2022]
Abstract
The widespread use of genomic copy number analysis has revealed many previously unknown genomic structural variations, including some which are more complex. In this study, three consecutive microdeletions were identified in the same chromosome by microarray-based comparative genomic hybridization (aCGH) analysis for a patient with a neurodevelopmental disorder. Subsequent fluorescence in situ hybridization (FISH) analyses unexpectedly suggested complicated translocations and inversions. For better understanding of the mechanism, breakpoint junctions were analyzed by nanopore sequencing, as a new long-read whole-genome sequencing (WGS) tool. The results revealed a new chromosomal disruption, giving rise to four junctions in chromosome 7. According the sequencing results of breakpoint junctions, all junctions were considered as the consequence of multiple double-strand breaks and the reassembly of DNA fragments by nonhomologous end-joining, indicating chromothripsis. KMT2E, located within the deletion region, was considered as the gene responsible for the clinical features of the patient. Combinatory usage of aCGH and FISH analyses would be recommended for interpretation of structural variations analyzed through WGS.
Collapse
|
8
|
Li H, Okada H, Suzuki S, Sakai K, Izumi H, Matsushima Y, Ichinohe N, Goto YI, Okada T, Inoue K. Gene suppressing therapy for Pelizaeus-Merzbacher disease using artificial microRNA. JCI Insight 2019; 4:125052. [PMID: 31092737 DOI: 10.1172/jci.insight.125052] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Accepted: 04/17/2019] [Indexed: 11/17/2022] Open
Abstract
Copy number increase or decrease of certain dosage-sensitive genes may cause genetic diseases with distinct phenotypes, conceptually termed genomic disorders. The most common cause of Pelizaeus-Merzbacher disease (PMD), an X-linked hypomyelinating leukodystrophy, is genomic duplication encompassing the entire proteolipid protein 1 (PLP1) gene. Although the exact molecular and cellular mechanisms underlying PLP1 duplication, which causes severe hypomyelination in the central nervous system, remain largely elusive, PLP1 overexpression is likely the fundamental cause of this devastating disease. Here, we investigated if adeno-associated virus-mediated (AAV-mediated) gene-specific suppression may serve as a potential cure for PMD by correcting quantitative aberrations in gene products. We developed an oligodendrocyte-specific Plp1 gene suppression therapy using artificial microRNA under the control of human CNP promoter in a self-complementary AAV (scAAV) platform. A single direct brain injection achieved widespread oligodendrocyte-specific Plp1 suppression in the white matter of WT mice. AAV treatment in Plp1-transgenic mice, a PLP1 duplication model, ameliorated cytoplasmic accumulation of Plp1, preserved mature oligodendrocytes from degradation, restored myelin structure and gene expression, and improved survival and neurological phenotypes. Together, our results provide evidence that AAV-mediated gene suppression therapy can serve as a potential cure for PMD resulting from PLP1 duplication and possibly for other genomic disorders.
Collapse
Affiliation(s)
- Heng Li
- Department of Mental Retardation and Birth Defect Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Hironori Okada
- Department of Molecular and Medical Genetics, Graduate School of Medicine, Nippon Medical School, Tokyo, Japan
| | - Sadafumi Suzuki
- Department of Mental Retardation and Birth Defect Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Kazuhisa Sakai
- Department of Ultrastructural Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Hitomi Izumi
- Department of Mental Retardation and Birth Defect Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Yukiko Matsushima
- Department of Mental Retardation and Birth Defect Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Noritaka Ichinohe
- Department of Ultrastructural Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Yu-Ichi Goto
- Department of Mental Retardation and Birth Defect Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Takashi Okada
- Department of Molecular and Medical Genetics, Graduate School of Medicine, Nippon Medical School, Tokyo, Japan
| | - Ken Inoue
- Department of Mental Retardation and Birth Defect Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Tokyo, Japan
| |
Collapse
|
9
|
Inoue K. Pelizaeus-Merzbacher Disease: Molecular and Cellular Pathologies and Associated Phenotypes. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1190:201-216. [PMID: 31760646 DOI: 10.1007/978-981-32-9636-7_13] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Pelizaeus-Merzbacher disease (PMD) represents a group of disorders known as hypomyelinating leukodystrophies, which are characterized by abnormal development and maintenance of myelin in the central nervous system. PMD is caused by different types of mutations in the proteolipid protein 1 (PLP1) gene, which encodes a major myelin membrane lipoprotein. These mutations in the PLP1 gene result in distinct cellular and molecular pathologies and a spectrum of clinical phenotypes. In this chapter, I discuss the historical aspects and current understanding of the mechanisms underlying how different PLP1 mutations disrupt the normal process of myelination and result in PMD and other disorders.
Collapse
Affiliation(s)
- Ken Inoue
- Department of Mental Retardation and Birth Defect Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Kodaira, Tokyo, Japan.
| |
Collapse
|
10
|
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.
Collapse
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.
| |
Collapse
|
11
|
Wight PA. Effects of Intron 1 Sequences on Human PLP1 Expression: Implications for PLP1-Related Disorders. ASN Neuro 2017; 9:1759091417720583. [PMID: 28735559 PMCID: PMC5528184 DOI: 10.1177/1759091417720583] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Alterations in the myelin proteolipid protein gene ( PLP1) may result in rare X-linked disorders in humans such as Pelizaeus-Merzbacher disease and spastic paraplegia type 2. PLP1 expression must be tightly regulated since null mutations, as well as elevated PLP1 copy number, both lead to disease. Previous studies with Plp1-lacZ transgenic mice have demonstrated that mouse Plp1 ( mPlp1) intron 1 DNA (which accounts for slightly more than half of the gene) is required for the mPlp1 promoter to drive significant levels of reporter gene expression in brain. However not much is known about the mechanisms that control expression of the human PLP1 gene ( hPLP1). Therefore this review will focus on sequences in hPLP1 intron 1 DNA deemed important for hPLP1 gene activity as well as a couple of "human-specific" supplementary exons within the first intron which are utilized to generate novel splice variants, and the potential role that these sequences may play in PLP1-linked disorders.
Collapse
Affiliation(s)
- Patricia A Wight
- 1 Department of Physiology and Biophysics, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| |
Collapse
|
12
|
Inoue K. Cellular Pathology of Pelizaeus-Merzbacher Disease Involving Chaperones Associated with Endoplasmic Reticulum Stress. Front Mol Biosci 2017; 4:7. [PMID: 28286750 PMCID: PMC5323380 DOI: 10.3389/fmolb.2017.00007] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2016] [Accepted: 02/09/2017] [Indexed: 11/23/2022] Open
Abstract
Disease-causing mutations in genes encoding membrane proteins may lead to the production of aberrant polypeptides that accumulate in the endoplasmic reticulum (ER). These mutant proteins have detrimental conformational changes or misfolding events, which result in the triggering of the unfolded protein response (UPR). UPR is a cellular pathway that reduces ER stress by generally inhibiting translation, increasing ER chaperones levels, or inducing cell apoptosis in severe ER stress. This process has been implicated in the cellular pathology of many neurological disorders, including Pelizaeus-Merzbacher disease (PMD). PMD is a rare pediatric disorder characterized by the failure in the myelination process of the central nervous system (CNS). PMD is caused by mutations in the PLP1 gene, which encodes a major myelin membrane protein. Severe clinical PMD phenotypes appear to be the result of cell toxicity, due to the accumulation of PLP1 mutant proteins and not due to the lack of functional PLP1. Therefore, it is important to clarify the pathological mechanisms by which the PLP1 mutants negatively impact the myelin-generating cells, called oligodendrocytes, to overcome this devastating disease. This review discusses how PLP1 mutant proteins change protein homeostasis in the ER of oligodendrocytes, especially focusing on the reaction of ER chaperones against the accumulation of PLP1 mutant proteins that cause PMD.
Collapse
Affiliation(s)
- Ken Inoue
- Department of Mental Retardation and Birth Defect Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry Kodaira, Japan
| |
Collapse
|
13
|
Kang S, Shaikh AG. Acquired pendular nystagmus. J Neurol Sci 2017; 375:8-17. [PMID: 28320194 DOI: 10.1016/j.jns.2017.01.033] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2016] [Revised: 12/18/2016] [Accepted: 01/09/2017] [Indexed: 11/16/2022]
Abstract
Acquired pendular nystagmus is comprised of quasi-sinusoidal oscillations of the eyes significantly affecting gaze holding and clarity of vision. The most common causes of acquired pendular nystagmus include demyelinating disorders such as multiple sclerosis and the syndrome of ocular palatal tremor. However, several other deficits, such as pharmacological intoxication, metabolic and genetic disorders, and granulomatous disorders can lead to syndromes mimicking acquired pendular nystagmus. Study of the kinematic features of acquired pendular nystagmus has suggested a putative pathophysiology of an otherwise mysterious neurological disorder. Here we review clinical features of neurological deficits that co-occur with acquired pendular nystagmus. Subsequent discussion of the pathophysiology of individual forms of pendular nystagmus speculates on mechanisms of the underlying disease while providing insights into pharmacotherapy of nystagmus.
Collapse
Affiliation(s)
- Sarah Kang
- Department of Neurology, Case Western Reserve University, Cleveland, OH, USA; Daroff-DelOsso Ocular Motility Laboratory, Neurology Service, Louis Stoke VA Medical Center, Cleveland, OH, USA
| | - Aasef G Shaikh
- Department of Neurology, Case Western Reserve University, Cleveland, OH, USA; Daroff-DelOsso Ocular Motility Laboratory, Neurology Service, Louis Stoke VA Medical Center, Cleveland, OH, USA.
| |
Collapse
|
14
|
Abstract
High resolution fiber-Fluorescence in situ hybridization (FISH) is an advanced FISH technology that can effectively bridge the resolution gap between probe hybridizing on DNA molecules and chromosomal regions. Since various types of DNA and chromatin fibers can be generated reflecting different degrees of DNA/chromatin packaging status, fiber-FISH technology has been successfully used in diverse molecular cytogenetic/cytogenomic studies. Following a brief review of this technology, including its major development and increasing applications, typical protocols to generate DNA/chromatin fiber will be described, coupled with rationales, as well as technical tips. These released DNA/chromatin fibers are suitable for an array of cytogenetic/cytogenomic analyses.
Collapse
Affiliation(s)
- Christine J Ye
- The Division of Hematology/Oncology, Department of Internal Medicine, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Henry H Heng
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, 3226 Scott Hall, 540 E, Detroit, MI, 48201, USA.
- Department of Pathology, Wayne State University School of Medicine, Detroit, MI, 48201, USA.
- Karmanos Cancer Institute, Detroit, MI, 48201, USA.
| |
Collapse
|
15
|
Laukka JJ, Kamholz J, Bessert D, Skoff RP. Novel pathologic findings in patients with Pelizaeus-Merzbacher disease. Neurosci Lett 2016; 627:222-32. [PMID: 27222925 PMCID: PMC4948744 DOI: 10.1016/j.neulet.2016.05.028] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Revised: 05/13/2016] [Accepted: 05/14/2016] [Indexed: 10/21/2022]
Abstract
Pelizaeus-Merzbacher disease (PMD) is an X-linked inherited hypomyelinating disorder caused by mutations in the gene encoding proteolipid protein (PLP), the major structural protein in central nervous system (CNS) myelin. Prior to our study, whether hypomyelination in PMD was caused by demyelination, abnormally thin sheaths or failure to form myelin was unknown. In this study, we compared the microscopic pathology of myelin from brain tissue of 3 PMD patients with PLP1 duplications to that of a patient with a complete PLP1 deletion. Autopsy tissue procured from PMD patients was embedded in paraffin for immunocytochemistry and plastic for electron microscopy to obtain highresolution fiber pathology of cerebrum and corpus callosum. Through histological stains, immunocytochemistry and electron microscopy, our study illustrates unique pathologic findings between the two different types of mutations. Characteristic of the patient with a PLP1 deletion, myelin sheaths showed splitting and decompaction of myelin, confirming for the first time that myelin in PLP1 deletion patients is similar to that of rodent models with gene deletions. Myelin thickness and g-ratios of some fibers, in relation to axon diameter was abnormally thin, suggesting that oligodendrocytes remain metabolically functional and/or are attempting to make myelin. Many fibers showed swollen, progressive degenerative changes to axons in addition to the dissolution of myelin. All three duplication cases shared remarkable fiber pathology including swellings, constriction and/or transection and involution of myelin. Characteristic of PLP1 duplication patients, many axons showed segmental demyelination along their length. Still other axons had abnormally thick myelin sheaths, suggestive of continued myelination. Thus, each type of mutation exhibited unique pathology even though commonality to both mutations included involution of myelin, myelin balls and degeneration of axons. This pathology study describes findings unique to each mutation that suggests the mechanism causing fiber pathology is likewise heterogeneous.
Collapse
Affiliation(s)
- Jeremy J Laukka
- Department of Neuroscience, University of Toledo, College of Medicine and Life Science, Toledo, OH 43614, United States; Department of Neurology, University of Toledo, College of Medicine and Life Science, Toledo, OH 43614, United States.
| | - John Kamholz
- Center for Molecular Medicine and Genetics, Wayne State University, School of Medicine, Detroit, MI 48201, United States; Department of Neurology, University of Iowa, Carver College of Medicine, Iowa City, IA 52242, United States
| | - Denise Bessert
- Department of Anatomy and Cell Biology, Wayne State University, School of Medicine, Detroit, MI 48201, United States
| | - Robert P Skoff
- Center for Molecular Medicine and Genetics, Wayne State University, School of Medicine, Detroit, MI 48201, United States; Department of Anatomy and Cell Biology, Wayne State University, School of Medicine, Detroit, MI 48201, United States
| |
Collapse
|
16
|
Osaka H, Inoue K. Pathophysiology and emerging therapeutic strategies in Pelizaeus–Merzbacher disease. Expert Opin Orphan Drugs 2015. [DOI: 10.1517/21678707.2015.1106315] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
|
17
|
Lupski JR. Structural variation mutagenesis of the human genome: Impact on disease and evolution. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2015; 56:419-36. [PMID: 25892534 PMCID: PMC4609214 DOI: 10.1002/em.21943] [Citation(s) in RCA: 91] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2015] [Accepted: 02/01/2015] [Indexed: 05/19/2023]
Abstract
Watson-Crick base-pair changes, or single-nucleotide variants (SNV), have long been known as a source of mutations. However, the extent to which DNA structural variation, including duplication and deletion copy number variants (CNV) and copy number neutral inversions and translocations, contribute to human genome variation and disease has been appreciated only recently. Moreover, the potential complexity of structural variants (SV) was not envisioned; thus, the frequency of complex genomic rearrangements and how such events form remained a mystery. The concept of genomic disorders, diseases due to genomic rearrangements and not sequence-based changes for which genomic architecture incite genomic instability, delineated a new category of conditions distinct from chromosomal syndromes and single-gene Mendelian diseases. Nevertheless, it is the mechanistic understanding of CNV/SV formation that has promoted further understanding of human biology and disease and provided insights into human genome and gene evolution. Environ. Mol. Mutagen. 56:419-436, 2015. © 2015 Wiley Periodicals, Inc.
Collapse
Affiliation(s)
- James R Lupski
- Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza Room 604B, Houston, Texas
| |
Collapse
|
18
|
Complex genomic rearrangements at the PLP1 locus include triplication and quadruplication. PLoS Genet 2015; 11:e1005050. [PMID: 25749076 PMCID: PMC4352052 DOI: 10.1371/journal.pgen.1005050] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2014] [Accepted: 02/02/2015] [Indexed: 02/07/2023] Open
Abstract
Inverted repeats (IRs) can facilitate structural variation as crucibles of genomic rearrangement. Complex duplication-inverted triplication-duplication (DUP-TRP/INV-DUP) rearrangements that contain breakpoint junctions within IRs have been recently associated with both MECP2 duplication syndrome (MIM#300260) and Pelizaeus-Merzbacher disease (PMD, MIM#312080). We investigated 17 unrelated PMD subjects with copy number gains at the PLP1 locus including triplication and quadruplication of specific genomic intervals-16/17 were found to have a DUP-TRP/INV-DUP rearrangement product. An IR distal to PLP1 facilitates DUP-TRP/INV-DUP formation as well as an inversion structural variation found frequently amongst normal individuals. We show that a homology-or homeology-driven replicative mechanism of DNA repair can apparently mediate template switches within stretches of microhomology. Moreover, we provide evidence that quadruplication and potentially higher order amplification of a genomic interval can occur in a manner consistent with rolling circle amplification as predicted by the microhomology-mediated break induced replication (MMBIR) model.
Collapse
|
19
|
Mayer JA, Griffiths IR, Goldman JE, Smith CM, Cooksey E, Radcliff AB, Duncan ID. Modeling the natural history of Pelizaeus-Merzbacher disease. Neurobiol Dis 2015; 75:115-30. [PMID: 25562656 PMCID: PMC4492172 DOI: 10.1016/j.nbd.2014.12.023] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2014] [Revised: 12/10/2014] [Accepted: 12/23/2014] [Indexed: 11/27/2022] Open
Abstract
Major gaps in our understanding of the leukodystrophies result from their rarity and the lack of tissue for the interdisciplinary studies required to extend our knowledge of the pathophysiology of the diseases. This study details the natural evolution of changes in the CNS of the shaking pup (shp), a model of the classical form of the X-linked disorder Pelizaeus-Merzbacher disease, in particular in glia, myelin, and axons, which is likely representative of what occurs over time in the human disease. The mutation in the proteolipid protein gene, PLP1, leads to a delay in differentiation, increased cell death, and a marked distension of the rough endoplasmic reticulum in oligodendrocytes. However, over time, more oligodendrocytes differentiate and survive in the spinal cord leading to an almost total recovery of myelination, In contrast, the brain remains persistently hypomyelinated. These data suggest that shp oligodendrocytes may be more functional than previously realized and that their early recruitment could have therapeutic value.
Collapse
Affiliation(s)
- Joshua A Mayer
- Department of Medical Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Ian R Griffiths
- Department of Veterinary Clinical Studies, University of Glasgow, Bearsden, Glasgow G61 1QH, Scotland
| | - James E Goldman
- Department of Pathology & Cell Biology, Columbia University, New York, NY 10027, USA
| | - Chelsey M Smith
- Department of Medical Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Elizabeth Cooksey
- Department of Medical Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Abigail B Radcliff
- Department of Medical Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Ian D Duncan
- Department of Medical Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, WI 53706, USA.
| |
Collapse
|
20
|
Hamdan H, Kockara NT, Jolly LA, Haun S, Wight PA. Control of human PLP1 expression through transcriptional regulatory elements and alternatively spliced exons in intron 1. ASN Neuro 2015; 7:7/1/1759091415569910. [PMID: 25694552 PMCID: PMC4342368 DOI: 10.1177/1759091415569910] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
These authors contributed equally to this work. Although the myelin proteolipid protein gene (PLP1) encodes the most abundant protein in central nervous system (CNS) myelin, not much is known about the mechanisms that govern expression of the human gene (hPLP1). Much more is known about the processes that regulate Plp1 gene expression in rodents. From studies with Plp1-lacZ transgenic mice, it was determined that the first intron of mouse Plp1 (mPlp1) is required to attain high levels of expression in brain, concurrent with the active myelination period. Other studies have suggested that within mPlp1 intron 1 (>8 kb) lie several regions with enhancer-like activity. To test whether these sequences (and possibly others) in hPLP1 intron 1 are functional, deletion-transfection analysis was performed with hPLP1-lacZ constructs that contain various portions of the intron, or lack it altogether. Results presented here demonstrate the importance of hPLP1 intron 1 in achieving maximal levels of expression in the immortalized oligodendroglial cell line, Oli-neu. Deletion analysis indicates that the intron contains multiple positive regulatory elements which are active in Oli-neu cells. Some of these elements appear to be functionally conserved between human and mouse, while others are not. Furthermore, our studies demonstrate that multiple splice variants can be formed due to inclusion of extra (supplementary) exons from what is classically thought of as hPLP1 intron 1. Thus, splicing of these novel exons (which are not recognized as such in mPlp1 due to lack of conserved splice sites) must utilize factors common to both human and mouse since Oli-neu cells are of mouse origin.
Collapse
Affiliation(s)
- Hamdan Hamdan
- Department of Physiology and Biophysics, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Neriman T Kockara
- Department of Physiology and Biophysics, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Lee Ann Jolly
- Department of Physiology and Biophysics, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Shirley Haun
- Department of Physiology and Biophysics, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Patricia A Wight
- Department of Physiology and Biophysics, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| |
Collapse
|
21
|
|
22
|
Epidemiological, clinical, and genetic landscapes of hypomyelinating leukodystrophies. J Neurol 2014; 261:752-8. [DOI: 10.1007/s00415-014-7263-5] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2013] [Revised: 01/22/2014] [Accepted: 01/23/2014] [Indexed: 01/08/2023]
|
23
|
Morimura T, Numata Y, Nakamura S, Hirano E, Gotoh L, Goto YI, Urushitani M, Inoue K. Attenuation of endoplasmic reticulum stress in Pelizaeus-Merzbacher disease by an anti-malaria drug, chloroquine. Exp Biol Med (Maywood) 2014; 239:489-501. [PMID: 24521562 DOI: 10.1177/1535370213520108] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Pelizaeus-Merzbacher disease (PMD) is a hypomyelinating disorder caused by the duplication and missense mutations of the proteolipid protein 1 (PLP1) gene. PLP1 missense proteins accumulate in the endoplasmic reticulum (ER) of premature oligodendrocytes and induce severe ER stress followed by apoptosis of the cells. Here, we demonstrate that an anti-malaria drug, chloroquine, decreases the amount of an ER-resident mutant PLP1 containing an alanine-243 to valine (A243V) substitution, which induces severe PMD in human. By preventing mutant PLP1 translation through enhancing the phosphorylation of eukaryotic initiation factor 2 alpha, chloroquine ameliorated the ER stress induced by the mutant protein in HeLa cells. Chroloquine also attenuated ER stress in the primary oligodendrocytes obtained from myelin synthesis deficit (msd) mice, which carry the same PLP1 mutation. In the spinal cords of msd mice, chloroquine inhibited ER stress and upregulated the expression of marker genes of mature oligodendrocytes. Chloroquine-mediated attenuation of ER stress was observed in HeLa cells treated with tunicamycin, an N-glycosylation inhibitor, but not with thapsigargin, a sarco/ER Ca(2+)ATPase inhibitor, which confirms its efficacy against ER stress caused by nascent proteins. These findings indicate that chloroquine is an ER stress attenuator with potential use in treating PMD and possibly other ER stress-related diseases.
Collapse
Affiliation(s)
- Toshifumi Morimura
- Department of Mental Retardation and Birth Defect Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry (NCNP), 4-1-1 Ogawahigashi-machi, Kodaira-shi, Tokyo 187-8502, Japan
| | | | | | | | | | | | | | | |
Collapse
|
24
|
Clinically relevant intronic splicing enhancer mutation in myelin proteolipid protein leads to progressive microglia and astrocyte activation in white and gray matter regions of the brain. J Neuroinflammation 2013; 10:146. [PMID: 24314267 PMCID: PMC3906979 DOI: 10.1186/1742-2094-10-146] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2013] [Accepted: 11/27/2013] [Indexed: 02/06/2023] Open
Abstract
INTRODUCTION Mutations in proteolipid protein (PLP), the most abundant myelin protein in the CNS, cause the X-linked dysmyelinating leukodystrophies, Pelizaeus-Merzbacher disease (PMD) and spastic paraplegia type 2 (SPG2). Point mutations, deletion, and duplication of the PLP1 gene cause PMD/SPG2 with varying clinical presentation. Deletion of an intronic splicing enhancer (ISEdel) within intron 3 of the PLP1 gene is associated with a mild form of PMD. Clinical and preclinical studies have indicated that mutations in myelin proteins, including PLP, can induce neuroinflammation, but the temporal and spatial onset of the reactive glia response in a clinically relevant mild form of PMD has not been defined. METHODS A PLP-ISEdel knockin mouse was used to examine the behavioral and neuroinflammatory consequences of a deletion within intron 3 of the PLP gene, at two time points (two and four months old) early in the pathological progression. Mice were characterized functionally using the open field task, elevated plus maze, and nesting behavior. Quantitative neuropathological analysis was for markers of astrocytes (GFAP), microglia (IBA1, CD68, MHCII) and axons (APP). The Aperio ScanScope was used to generate a digital, high magnification photomicrograph of entire brain sections. These digital slides were used to quantify the immunohistochemical staining in ten different brain regions to assess the regional heterogeneity in the reactive astrocyte and microglial response. RESULTS The PLP-ISEdel mice exhibited behavioral deficits in the open field and nesting behavior at two months, which did not worsen by four months of age. A marker of axonal injury (APP) increased from two months to four months of age. Striking was the robust reactive astrocyte and microglia response which was also progressive. In the two-month-old mice, the astrocyte and microglia reactivity was most apparent in white matter rich regions of the brain. By four months of age the gliosis had become widespread and included both white as well as gray matter regions of the brain. CONCLUSIONS Our results indicate, along with other preclinical models of PMD, that an early reactive glia response occurs following mutations in the PLP gene, which may represent a potentially clinically relevant, oligodendrocyte-independent therapeutic target for PMD.
Collapse
|
25
|
Noetzli L, Sanz PG, Brodsky GL, Hinckley JD, Giugni JC, Giannaula RJ, Gonzalez-Alegre P, Di Paola J. A novel mutation in PLP1 causes severe hereditary spastic paraplegia type 2. Gene 2013; 533:447-50. [PMID: 24103481 DOI: 10.1016/j.gene.2013.09.076] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2013] [Revised: 09/18/2013] [Accepted: 09/22/2013] [Indexed: 01/10/2023]
Abstract
Hereditary spastic paraplegia (HSP) type 2 is a proteolipid protein (PLP1)-related genetic disorder that is characterized by dysmyelination of the central nervous system resulting primarily in limb spasticity, cognitive impairment, nystagmus, and spastic urinary bladder of varying severity. Previously reported PLP1 mutations include duplications, point mutations, or whole gene deletions with a continuum of phenotypes ranging from severe Pelizaeus-Merzbacher disease (PMD) to uncomplicated HSP type 2. In this manuscript we report a novel PLP1 missense mutation (c.88G>C) in a family from Argentina. This mutation is in a highly conserved transmembrane domain of PLP1 and the mutant protein was found to be retained in the endoplasmic reticulum when expressed in vitro. Due to the variable expressivity that characterizes these disorders our report contributes to the knowledge of genotype-phenotype correlations of PLP1-related disorders.
Collapse
Affiliation(s)
- Leila Noetzli
- Department of Pediatrics, University of Colorado Denver School of Medicine, USA; Human Medical Genetics and Genomics Program, University of Colorado Denver School of Medicine, USA
| | | | | | | | | | | | | | | |
Collapse
|
26
|
Giorgio E, Rolyan H, Kropp L, Chakka AB, Yatsenko S, Gregorio ED, Lacerenza D, Vaula G, Talarico F, Mandich P, Toro C, Pierre EE, Labauge P, Capellari S, Cortelli P, Vairo FP, Miguel D, Stubbolo D, Marques LC, Gahl W, Boespflug-Tanguy O, Melberg A, Hassin-Baer S, Cohen OS, Pjontek R, Grau A, Klopstock T, Fogel B, Meijer I, Rouleau G, Bouchard JPL, Ganapathiraju M, Vanderver A, Dahl N, Hobson G, Brusco A, Brussino A, Padiath QS. Analysis of LMNB1 duplications in autosomal dominant leukodystrophy provides insights into duplication mechanisms and allele-specific expression. Hum Mutat 2013; 34:1160-71. [PMID: 23649844 PMCID: PMC3714349 DOI: 10.1002/humu.22348] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2013] [Accepted: 04/19/2013] [Indexed: 02/05/2023]
Abstract
Autosomal dominant leukodystrophy (ADLD) is an adult onset demyelinating disorder that is caused by duplications of the lamin B1 (LMNB1) gene. However, as only a few cases have been analyzed in detail, the mechanisms underlying LMNB1 duplications are unclear. We report the detailed molecular analysis of the largest collection of ADLD families studied, to date. We have identified the minimal duplicated region necessary for the disease, defined all the duplication junctions at the nucleotide level and identified the first inverted LMNB1 duplication. We have demonstrated that the duplications are not recurrent; patients with identical duplications share the same haplotype, likely inherited from a common founder and that the duplications originated from intrachromosomal events. The duplication junction sequences indicated that nonhomologous end joining or replication-based mechanisms such fork stalling and template switching or microhomology-mediated break induced repair are likely to be involved. LMNB1 expression was increased in patients' fibroblasts both at mRNA and protein levels and the three LMNB1 alleles in ADLD patients show equal expression, suggesting that regulatory regions are maintained within the rearranged segment. These results have allowed us to elucidate duplication mechanisms and provide insights into allele-specific LMNB1 expression levels.
Collapse
Affiliation(s)
- Elisa Giorgio
- University of Torino, Department of Medical SciencesTorino, Italy
| | - Harshvardhan Rolyan
- Department of Human Genetics Graduate School of Public Health, University of PittsburghPittsburgh, Pennsylvania
| | - Laura Kropp
- Department of Human Genetics Graduate School of Public Health, University of PittsburghPittsburgh, Pennsylvania
| | - Anish Baswanth Chakka
- Department of Biomedical Informatics School of Medicine, University of PittsburghPittsburgh, Pennsylvania
| | - Svetlana Yatsenko
- Department of Obstetrics Gynecology and Reproductive Sciences, University of PittsburghPittsburgh, Pennsylvania
- Department of Pathology University of Pittsburgh, School of MedicinePittsburgh, Pennsylvania
| | - Eleonora Di Gregorio
- University of Torino, Department of Medical SciencesTorino, Italy
- S.C.D.U. Medical Genetics, Az. Osp. Città della Salute e della ScienzaTorino, Italy
| | | | - Giovanna Vaula
- Department of Neuroscience, Az. Osp. Città della Salute e della ScienzaTorino, Italy
| | - Flavia Talarico
- S.C.D.U. Medical Genetics, Az. Osp. Città della Salute e della ScienzaTorino, Italy
| | - Paola Mandich
- Department of Neurology, Ophthalmology and Genetics, di Bologna, Department of Biomedical and NeuroMotor Sciences (DIBINEM) Alma Mater StudiorumBologna, Italy
| | - Camilo Toro
- NIH Undiagnosed Diseases Program NIH Office of Rare Disease, Research and NHGRIBethesda, Maryland
| | | | - Pierre Labauge
- Neurologie Hopital Caremeau, Centre Hospitalo-Universitaire de NimesNimes, France
| | - Sabina Capellari
- University of Bologna IRCCS Istituto delle Scienze Neurologiche di Bologna Department of Biomedical and NeuroMotor Sciences (DIBINEM), Alma Mater StudiorumItaly
| | - Pietro Cortelli
- University of Bologna IRCCS Istituto delle Scienze Neurologiche di Bologna Department of Biomedical and NeuroMotor Sciences (DIBINEM), Alma Mater StudiorumItaly
| | - Filippo Pinto Vairo
- Hospital de Clínicas de Porto Alegre … Universidade Federal do Rio Grande do SulPorto Alegre, Brazil
| | - Diego Miguel
- Hospital de Clínicas de Porto Alegre … Universidade Federal do Rio Grande do SulPorto Alegre, Brazil
| | - Danielle Stubbolo
- Nemours Biomedical Research, Alfred I. duPont Hospital for ChildrenWilmington, Delaware
| | - Lourenco Charles Marques
- Department of Medical Genetics Clinics Hospital of Ribeirao Preto, University of Sao PauloSao Paulo, Brazil
| | - William Gahl
- NIH Undiagnosed Diseases Program NIH Office of Rare Disease, Research and NHGRIBethesda, Maryland
| | - Odile Boespflug-Tanguy
- Institut National de la Santé et de la Recherche Médicale (INSERM) – Paris Diderot Sorbonne Paris Cité University, Robert Debré HospitalParis, France
- Assistance Publique des Hopitaux de Paris Reference Center for Rare Diseases “Leukodystrophies”, Child Neurology and Metabolic Disorders DepartmentParis, France
| | - Atle Melberg
- Department of Neuroscience Neurology, Uppsala UniversityUppsala, Sweden
| | - Sharon Hassin-Baer
- Parkinson’s disease and Movement Disorders Clinic Department of Neurology, Chaim Sheba Medical CenterTel Aviv, Israel
- Sackler Faculty of Medicine, Tel Aviv UniversityTel Aviv, Israel
| | - Oren S Cohen
- Parkinson’s disease and Movement Disorders Clinic Department of Neurology, Chaim Sheba Medical CenterTel Aviv, Israel
- Sackler Faculty of Medicine, Tel Aviv UniversityTel Aviv, Israel
| | - Rastislav Pjontek
- Department of Neurology, University of HeidelbergHeidelberg, Germany
| | - Armin Grau
- Dept. of Neurology, Klinikum LudwigshafenLudwigshafen, Germany
| | - Thomas Klopstock
- Dept. of Neurology Friedrich-Baur-Institute, Ludwig-Maximilians-UniversityMunich, Germany
- German Center for Vertigo and Balance DisordersMunich, Germany
- DZNE – German Center for Neurodegenerative DiseasesMunich, Germany
- German Network for Mitochondrial Disorders(mitoNET), Germany
| | - Brent Fogel
- Department of Neurology David Geffen School of Medicine, University of CaliforniaLos Angeles, California
| | - Inge Meijer
- Montreal Neurological Institute, McGill UniversityMontreal, Canada
| | - Guy Rouleau
- Montreal Neurological Institute, McGill UniversityMontreal, Canada
| | | | - Madhavi Ganapathiraju
- Department of Biomedical Informatics School of Medicine, University of PittsburghPittsburgh, Pennsylvania
| | - Adeline Vanderver
- Department of Neurology, Childrens National Medical CenterWashington, District of Columbia
| | - Niklas Dahl
- Dept. of Immunology Genetics and Pathology Section of Clinical Genetics The Rudbeck laboratory, Uppsala University Children’s HospitalUppsala, Sweden
| | - Grace Hobson
- Nemours Biomedical Research, Alfred I. duPont Hospital for ChildrenWilmington, Delaware
- University of Delaware, Department of BiologyNewark, Delaware
- Thomas Jefferson University, Jefferson Medical CollegePhiladelphia, Pennsylvania
| | - Alfredo Brusco
- University of Torino, Department of Medical SciencesTorino, Italy
- S.C.D.U. Medical Genetics, Az. Osp. Città della Salute e della ScienzaTorino, Italy
| | | | - Quasar Saleem Padiath
- Department of Human Genetics Graduate School of Public Health, University of PittsburghPittsburgh, Pennsylvania
| |
Collapse
|
27
|
Kimura-Ohba S, Kagitani-Shimono K, Hashimoto N, Nabatame S, Okinaga T, Murakami A, Miyake N, Matsumoto N, Osaka H, Hojo K, Tomita R, Taniike M, Ozono K. A case of cerebral hypomyelination with spondylo-epi-metaphyseal dysplasia. Am J Med Genet A 2012; 161A:203-7. [PMID: 23239615 DOI: 10.1002/ajmg.a.35686] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2011] [Accepted: 09/07/2012] [Indexed: 11/12/2022]
Abstract
We reported on a male patient with rare leukoencephalopathy and skeletal abnormalities. The condition was first noticed as a developmental delay, nystagmus and ataxia at 1 year of age. At 4 years of age, he was diagnosed as hypomyelination with skeletal abnormalities from clinical features, brain magnetic resonance imaging (MRI) and skeletal X-rays. His brain MRI revealed diffuse hypomyelination. These findings suggested the classical type of Pelizaeus-Merzbacher disease (PMD) caused by proteolipid protein (PLP)-1 gene or Pelizaeus-Merzbacher-like disease (PMLD). However, we found neither mutation nor duplication of PLP-1. The patient had severe growth retardation and general skeletal dysplasia compatible with spondylo-epi-metaphyseal dysplasia; however the mutation of discoidin domain receptor (DDR) 2 gene was absent. The co-morbidity of hypomyelination with skeletal abnormalities is rare. We performed array CGH and no causal copy number variation was recognized. Alternatively, this condition may have been caused by a mutation of the gene encoding a molecule that functions in both cerebral myelination and skeletal development.
Collapse
Affiliation(s)
- Shihoko Kimura-Ohba
- Department of Pediatrics, Osaka University Graduate School of Medicine, Osaka, Japan.
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
28
|
Abstract
OBJECTIVES To characterize at clinical and molecular levels a family presenting with X-linked recessive Hereditary Spastic Paraplegia (HSP). BACKGROUND HSPs are a large group of genetically heterogeneous neurodegenerative disorders characterized by progressive upper motor neuron signs. Mutations in the proteolipid protein (PLP1) gene have been identified in families linked to the SPG2 locus on chromosome Xq22. However, Pelizaeus-Merzbacher disease (PMD) is also an X-linked recessive neurological disorder caused by PLP1 mutations. METHODS The SPG2 locus was investigated by linkage analysis in the family. The PLP1 gene was screened by sequencing. We present findings in a large French-Canadian family with an X-linked recessive HSP. The proband presented early with developmental delay and developed progressive spastic paraplegia. He has been wheelchair-bound since the age of three years. At the latest follow-up, he was 20 years-old and had severe spasticity predominantly affecting the lower extremities, moderate cerebellar dysfunction, and optic atrophy. RESULTS Linkage to SPG2 was established and a G to A mutation (M1R) in the initiation codon of the PLP1 gene was identified, likely resulting in the complete absence of proteolipid protein. CONCLUSIONS We report a new PLP1 gene mutation in a patient with a clinical phenotype consistent with a PLP1 null syndrome.
Collapse
|
29
|
Bilir B, Yapici Z, Yalcinkaya C, Baris I, Carvalho CMB, Bartnik M, Ozes B, Eraksoy M, Lupski JR, Battaloglu E. High frequency of GJA12/GJC2 mutations in Turkish patients with Pelizaeus-Merzbacher disease. Clin Genet 2012; 83:66-72. [PMID: 22283455 DOI: 10.1111/j.1399-0004.2012.01846.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Pelizaeus-Merzbacher disease is an early onset dysmyelinating leukodystrophy. About 80% of PMD cases have been associated with duplications and mutations of the proteolipid protein 1 (PLP1) gene. Pelizaeus-Merzbacher-like disease is a genetically heterogeneous autosomal recessive disease and rarely caused by mutations in gap junction protein α12 (GJA12/GJC2) gene. The molecular basis of the disease was investigated in a cohort of 19 Turkish families. This study identified novel chromosomal rearrangements proximal and distal to, and exclusive of the PLP1 gene, showed equal frequencies of PLP1 and GJA12/GJC2 mutations at least in our cohort, and suggested further genetic heterogeneity.
Collapse
Affiliation(s)
- B Bilir
- Department of Molecular Biology and Genetics, Bogazici University, Istanbul, Turkey
| | | | | | | | | | | | | | | | | | | |
Collapse
|
30
|
Fonseca ACS, Bonaldi A, Costa SS, Freitas MR, Kok F, Vianna-Morgante AM. PLP1 duplication at the breakpoint regions of an apparently balanced t(X;22) translocation causes Pelizaeus-Merzbacher disease in a girl. Clin Genet 2012; 83:169-74. [PMID: 22320281 DOI: 10.1111/j.1399-0004.2012.01854.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
PLP1 (proteolipid protein1 gene) mutations cause Pelizaeus-Merzbacher disease (PMD), characterized by hypomyelination of the central nervous system, and affecting almost exclusively males. We report on a girl with classical PMD who carries an apparently balanced translocation t(X;22)(q22;q13). By applying array-based comparative genomic hybridization (a-CGH), we detected duplications at 22q13 and Xq22, encompassing 487-546 kb and 543-611 kb, respectively. The additional copies were mapped by fluorescent in situ hybridization to the breakpoint regions, on the derivative X chromosome (22q13 duplicated segment) and on the derivative 22 chromosome (Xq22 duplicated segment). One of the 14 duplicated X-chromosome genes was PLP1.The normal X chromosome was the inactive one in the majority of peripheral blood leukocytes, a pattern of inactivation that makes cells functionally balanced for the translocated segments. However, a copy of the PLP1 gene on the derivative chromosome 22, in addition to those on the X and der(X) chromosomes, resulted in two active copies of the gene, irrespective of the X-inactivation pattern, thus causing PMD. This t(X;22) is the first constitutional human apparently balanced translocation with duplications from both involved chromosomes detected at the breakpoint regions.
Collapse
Affiliation(s)
- A C S Fonseca
- Departamento de Genética e Biologia Evolutiva, Instituto de Biociências, Universidade de São Paulo, São Paulo, Brazil
| | | | | | | | | | | |
Collapse
|
31
|
Aboody K, Capela A, Niazi N, Stern JH, Temple S. Translating stem cell studies to the clinic for CNS repair: current state of the art and the need for a Rosetta stone. Neuron 2011; 70:597-613. [PMID: 21609819 DOI: 10.1016/j.neuron.2011.05.007] [Citation(s) in RCA: 157] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/05/2011] [Indexed: 11/26/2022]
Abstract
Since their discovery twenty years ago and prospective isolation a decade later, neural stem cells (NSCs), their progenitors, and differentiated cell derivatives along with other stem-cell based strategies have advanced steadily toward clinical trials, spurred by the immense need to find reparative therapeutics for central nervous system (CNS) diseases and injury. Current phase I/II trials using stem cells in the CNS are the vanguard for the widely anticipated next generation of regenerative therapies and as such are pioneering the stem cell therapy process. While translation has typically been the purview of industry, academic researchers are increasingly driven to bring their findings toward treatments and face challenges in knowledge gap and resource access that are accentuated by the unique financial, manufacturing, scientific, and regulatory aspects of cell therapy. Solutions are envisioned that both address the significant unmet medical need and lead to increased funding for basic and translational research.
Collapse
Affiliation(s)
- Karen Aboody
- Department of Neurosciences and Division of Neurosurgery, City of Hope National Medical Center & Beckman Research Institute, Duarte, CA 91010, USA
| | | | | | | | | |
Collapse
|
32
|
Mayer JA, Larsen EC, Kondo Y, Duncan ID. Characterization of a PLP-overexpressing transgenic rat, a model for the connatal form of Pelizaeus-Merzbacher disease. Neurobiol Dis 2011; 44:231-8. [PMID: 21784154 DOI: 10.1016/j.nbd.2011.07.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2011] [Revised: 06/10/2011] [Accepted: 07/06/2011] [Indexed: 11/30/2022] Open
Abstract
Pelizaeus-Merzbacher disease (PMD) most frequently results from duplication of the Plp1 gene with a correlation between disease severity and increasing copy number of the gene. Animal models of PMD, in particular those overexpressing the Plp1 gene, have been sought in attempts to provide systems in which potential therapies can be tested. Here we describe a rat model of the severe connatal form of PMD and provide a detailed characterization of its pathology and molecular biology, prior to testing therapeutic approaches. We determined the exact copy number of Plp1, and the resulting effects on RNA and protein expression. Distinct differences in myelin and disparate distributions of myelin protein markers in comparison to wild-type controls were observed. Altered expression of Plp1 also caused an increase in the apoptotic cell death of oligodendrocytes. These results provide the platform from which to test the effectiveness of in vivo therapies.
Collapse
Affiliation(s)
- Joshua A Mayer
- Department of Medical Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, USA.
| | | | | | | |
Collapse
|
33
|
Carvalho CMB, Bartnik M, Pehlivan D, Fang P, Shen J, Lupski JR. Evidence for disease penetrance relating to CNV size: Pelizaeus-Merzbacher disease and manifesting carriers with a familial 11 Mb duplication at Xq22. Clin Genet 2011; 81:532-41. [PMID: 21623770 DOI: 10.1111/j.1399-0004.2011.01716.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The potential causes for the incomplete penetrance of Pelizaeus-Merzbacher disease (PMD) in female carriers of PLP1 mutations are not well understood. We present a family with a boy having PMD in association with PLP1 duplication and three females who are apparent manifesting carriers. Custom high-resolution oligonucleotide array comparative genomic hybridization (aCGH) and breakpoint junction sequencing were performed and revealed a familial complex duplication consisting of a small duplicated genomic interval (∼56 kb) and a large segmental duplication (∼11 Mb) that resulted in a PLP1 copy number variation gain. Breakpoint junction analysis implicates a replication-based mechanism underlying the rearrangement formation. X-inactivation studies (XCI) showed a random to moderate advantageous skewing pattern in peripheral blood cells but a moderate to extremely skewed (≥90%) pattern in buccal cells. In conclusion, our data show that complex duplications involving PLP1 are not uncommon, can be detected at the level of genome resolution afforded by clinical aCGH and duplication and inversion can be produced in the same event. Furthermore, the observation of three manifesting carriers with a large genomic rearrangement supports the contention that duplication size along with genomic content can be an important factor for penetrance of the PMD phenotype in females.
Collapse
Affiliation(s)
- C M B Carvalho
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | | | | | | | | | | |
Collapse
|
34
|
Kashork CD, Theisen A, Shaffer LG. Diagnosis of cryptic chromosomal syndromes by fluorescence in situ hybridization (FISH). CURRENT PROTOCOLS IN HUMAN GENETICS 2010; Chapter 8:Unit 8.10.1-20. [PMID: 20891031 DOI: 10.1002/0471142905.hg0810s67] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
This unit describes the various methods by which cytogeneticists detect chromosome abnormalities. The unit offers guidance for detecting such abnormalities with fluorescence in situ hybridization (FISH), as well as the benefits, limitations, and other applications of FISH.
Collapse
|
35
|
Comprehensive genetic analyses of PLP1 in patients with Pelizaeus-Merzbacher disease applied by array-CGH and fiber-FISH analyses identified new mutations and variable sizes of duplications. Brain Dev 2010; 32:171-9. [PMID: 19328639 DOI: 10.1016/j.braindev.2009.02.011] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/22/2008] [Revised: 02/02/2009] [Accepted: 02/22/2009] [Indexed: 12/12/2022]
Abstract
Pelizaeus-Merzbacher disease (PMD; MIM#312080) is a rare X-linked recessive neurodegenerative disorder. The main cause of PMD is alterations in the proteolipid protein 1 gene (PLP1) on chromosome Xq22.2. Duplications and point mutations of PLP1 have been found in 70% and 10-25% of all patients with PMD, respectively, with a wide clinical spectrum. Since the underlining genomic abnormalities are heterogeneous in patients with PMD, clarification of the genotype-phenotype correlation is the object of this study. Comprehensive genetic analyses using microarray-based comparative genomic hybridization (aCGH) analysis and genomic sequencing were applied to fifteen unrelated male patients with a clinical diagnosis of PMD. Duplicated regions were further analyzed by fiber-fluorescence in situ hybridization (FISH) analysis. Four novel and one known nucleotide alterations were identified in five patients. Five microduplications including PLP1 were identified by aCGH analysis with the sizes ranging from 374 to 951-kb. The directions of five PLP1 duplications were further investigated by fiber-FISH analysis, and all showed tandem duplications. The common manifestations of the disease in patients with PLP1 mutations or duplications in this study were nystagmus in early infancy, dysmyelination revealed by magnetic resonance imaging (MRI), and auditory brain response abnormalities. Although the grades of dysmyelination estimated by MRI findings were well correlated to the clinical phenotypes of the patients, there is no correlation between the size of the duplications and the phenotypic severity.
Collapse
|
36
|
Phylogeny of proteolipid proteins: divergence, constraints, and the evolution of novel functions in myelination and neuroprotection. ACTA ACUST UNITED AC 2009; 4:111-27. [PMID: 19497142 DOI: 10.1017/s1740925x0900009x] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The protein composition of myelin in the central nervous system (CNS) has changed at the evolutionary transition from fish to tetrapods, when a lipid-associated transmembrane-tetraspan (proteolipid protein, PLP) replaced an adhesion protein of the immunoglobulin superfamily (P0) as the most abundant constituent. Here, we review major steps of proteolipid evolution. Three paralog proteolipids (PLP/DM20/DMalpha, M6B/DMgamma and the neuronal glycoprotein M6A/DMbeta) exist in vertebrates from cartilaginous fish to mammals, and one (M6/CG7540) can be traced in invertebrate bilaterians including the planktonic copepod Calanus finmarchicus that possess a functional myelin equivalent. In fish, DMalpha and DMgamma are coexpressed in oligodendrocytes but are not major myelin components. PLP emerged at the root of tetrapods by the acquisition of an enlarged cytoplasmic loop in the evolutionary older DMalpha/DM20. Transgenic experiments in mice suggest that this loop enhances the incorporation of PLP into myelin. The evolutionary recruitment of PLP as the major myelin protein provided oligodendrocytes with the competence to support long-term axonal integrity. We suggest that the molecular shift from P0 to PLP also correlates with the concentration of adhesive forces at the radial component, and that the new balance between membrane adhesion and dynamics was favorable for CNS myelination.
Collapse
|
37
|
Arlt MF, Mulle JG, Schaibley VM, Ragland RL, Durkin SG, Warren ST, Glover TW. Replication stress induces genome-wide copy number changes in human cells that resemble polymorphic and pathogenic variants. Am J Hum Genet 2009; 84:339-50. [PMID: 19232554 PMCID: PMC2667984 DOI: 10.1016/j.ajhg.2009.01.024] [Citation(s) in RCA: 123] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2008] [Revised: 01/23/2009] [Accepted: 01/30/2009] [Indexed: 11/28/2022] Open
Abstract
Copy number variants (CNVs) are an important component of genomic variation in humans and other mammals. Similar de novo deletions and duplications, or copy number changes (CNCs), are now known to be a major cause of genetic and developmental disorders and to arise somatically in many cancers. A major mechanism leading to both CNVs and disease-associated CNCs is meiotic unequal crossing over, or nonallelic homologous recombination (NAHR), mediated by flanking repeated sequences or segmental duplications. Others appear to involve nonhomologous end joining (NHEJ) or aberrant replication suggesting a mitotic cell origin. Here we show that aphidicolin-induced replication stress in normal human cells leads to a high frequency of CNCs of tens to thousands of kilobases across the human genome that closely resemble CNVs and disease-associated CNCs. Most deletion and duplication breakpoint junctions were characterized by short (<6 bp) microhomologies, consistent with the hypothesis that these rearrangements were formed by NHEJ or a replication-coupled process, such as template switching. This is a previously unrecognized consequence of replication stress and suggests that replication fork stalling and subsequent error-prone repair are important mechanisms in the formation of CNVs and pathogenic CNCs in humans.
Collapse
Affiliation(s)
- Martin F. Arlt
- Department of Human Genetics, University of Michigan, Ann Arbor, MI 48109, USA
| | - Jennifer G. Mulle
- Department of Human Genetics, Emory University, Atlanta, GA 30322, USA
| | | | - Ryan L. Ragland
- Department of Human Genetics, University of Michigan, Ann Arbor, MI 48109, USA
| | - Sandra G. Durkin
- Department of Human Genetics, University of Michigan, Ann Arbor, MI 48109, USA
| | - Stephen T. Warren
- Department of Human Genetics, Emory University, Atlanta, GA 30322, USA
| | - Thomas W. Glover
- Department of Human Genetics, University of Michigan, Ann Arbor, MI 48109, USA
| |
Collapse
|
38
|
|
39
|
Abstract
Pelizaeus-Merzbacher disease (PMD) is a recessive X-linked dysmyelinating disorder of the central nervous system (CNS). The most frequent cause of PMD is a genomic duplication of chromosome Xq22 including the region encoding the dosage-sensitive proteolipid protein 1 (PLP1) gene. The PLP1 duplications are heterogeneous in size, unlike duplications causing many other genomic disorders, and arise by a distinct molecular mechanism. Other causes of PMD include PLP1 deletions, triplications and point mutations. Mutations in the PLP1 gene can also give rise to spastic paraplegia type 2 (SPG2), an allelic form of the disease. Thus, there is a spectrum of CNS disorder from mild SPG2 to severe connatal PMD. PLP1 encodes a major protein in CNS myelin and is abundantly expressed in oligodendrocytes, the myelinating cells of the CNS. Significant advances in our understanding of PMD have been achieved by investigating mutant PLP1 in PMD patients, animal models and in vitro studies. How the different PLP1 mutations and dosage effects give rise to PMD is being revealed. Interestingly, the underlying causes of pathogenesis are distinct for each of the different genetic abnormalities. This article reviews the genetics of PMD and summarises the current knowledge of causative molecular and cellular mechanisms.
Collapse
|
40
|
Heng HHQ, Windle B, Tsui LC. High-resolution FISH analysis. CURRENT PROTOCOLS IN HUMAN GENETICS 2008; Chapter 4:Unit 4.5. [PMID: 18428380 DOI: 10.1002/0471142905.hg0405s44] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Map order, orientation, and gap or overlap distance of closely linked DNA probes may be determined using fluorescent hybridization to decondensed DNA. The linear arrangement of released chromatin fibers not only simplifies the task of gene ordering, but also provides higher resolution with probes separated by greater distances than can be achieved in FISH with intact interphase nuclei. The Basic Protocol 1 of this unit describes an alkaline lysis procedure for generating free chromatin from cultured cells for FISH analysis. A support protocol describes an empirical approach to optimize conditions for preparation of free chromatin. An Alternate Protocol 1 provides a method for producing free chromatin from cultured lymphocytes with drug treatment. The Basic Protocol 2, high-resolution FISH mapping with free chromatin, is a modification of the method used for FISH mapping of interphase nuclei.
Collapse
Affiliation(s)
- Henry H Q Heng
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, Michigan, USA
| | | | | |
Collapse
|
41
|
Regis S, Biancheri R, Bertini E, Burlina A, Lualdi S, Bianco MG, Devescovi R, Rossi A, Uziel G, Filocamo M. Genotype-phenotype correlation in five Pelizaeus-Merzbacher disease patients with PLP1 gene duplications. Clin Genet 2008; 73:279-87. [DOI: 10.1111/j.1399-0004.2007.00961.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
42
|
A DNA Replication Mechanism for Generating Nonrecurrent Rearrangements Associated with Genomic Disorders. Cell 2007; 131:1235-47. [DOI: 10.1016/j.cell.2007.11.037] [Citation(s) in RCA: 662] [Impact Index Per Article: 38.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2007] [Revised: 10/10/2007] [Accepted: 11/14/2007] [Indexed: 01/17/2023]
|
43
|
Tanaka M, Hamano SI, Sakata H, Adachi N, Kaga K, Osaka H, Kurosawa K. Discrepancy between auditory brainstem responses, auditory steady-state responses, and auditory behavior in two patients with Pelizaeus-Merzbacher disease. Auris Nasus Larynx 2007; 35:404-7. [PMID: 18029128 DOI: 10.1016/j.anl.2007.09.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2007] [Revised: 08/16/2007] [Accepted: 09/14/2007] [Indexed: 11/16/2022]
Abstract
We reported two cases of Pelizaeus-Merzbacher disease. Both cases visited our hospital manifesting horizontal nystagmoid movements present from birth, and delayed motor development. Magnetic resonance imaging of the brain showed diffuse dysmyelination of the cerebral white matter, and auditory brainstem response showed waves I and II but absence of all subsequent components. Conditioned orientation reflex (COR) audiometry showed poor reactions in an infantile case whose development was severely retarded, and who spoke no meaningful words. Auditory steady-state response (ASSR) was a helpful tool for identifying her auditory ability; thereafter, her communication skills improved naturally. The other case was mildly developmentally retarded, and the results of COR audiometry and ASSR were considered the same level. The discrepancy between results of these hearing tests may arise under the influence of developmental level of the case.
Collapse
Affiliation(s)
- Manabu Tanaka
- Division of Neurology, Saitama Children's Medical Center, Saitama, Japan.
| | | | | | | | | | | | | |
Collapse
|
44
|
Lee JA, Cheung SW, Ward PA, Inoue K, Lupski JR. Prenatal diagnosis of PLP1 copy number by array comparative genomic hybridization. Prenat Diagn 2007; 25:1188-91. [PMID: 16353282 DOI: 10.1002/pd.1308] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
OBJECTIVES To report a family with a history of Pelizaeus-Merzbacher disease (PMD) for which prenatal diagnosis of PLP1 gene duplication status was attempted by the use of custom array comparative genomic hybridization (aCGH). METHODS A 28-year-old woman was referred for genetic counseling for her then current pregnancy because her existing 3-year-old son was diagnosed with a classic form of PMD. At 11 and 3/7 weeks gestation, chorionic villus sampling (CVS) was performed. Custom aCGH and fluorescence in situ hybridization (FISH) analyses were also performed on the DNA from family members. Fetal karyotyping revealed 46,XY. RESULTS Analysis by aCGH revealed that the male fetus was not duplicated for the PLP1 gene, but confirmed a duplicated PLP1 gene in the 3-year-old son, and that the mother was a duplication carrier. These results were independently confirmed by FISH analysis. aCGH and FISH analyses on DNA and cells derived from cord blood confirmed PLP1 nonduplication in the newborn. CONCLUSION aCGH is a reliable alternative method for detection of PLP1 copy number for prenatal diagnosis of Pelizaeus-Merzbacher disease.
Collapse
Affiliation(s)
- Jennifer A Lee
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77030, USA
| | | | | | | | | |
Collapse
|
45
|
Potocki L, Bi W, Treadwell-Deering D, Carvalho CMB, Eifert A, Friedman EM, Glaze D, Krull K, Lee JA, Lewis RA, Mendoza-Londono R, Robbins-Furman P, Shaw C, Shi X, Weissenberger G, Withers M, Yatsenko SA, Zackai EH, Stankiewicz P, Lupski JR. Characterization of Potocki-Lupski syndrome (dup(17)(p11.2p11.2)) and delineation of a dosage-sensitive critical interval that can convey an autism phenotype. Am J Hum Genet 2007; 80:633-49. [PMID: 17357070 PMCID: PMC1852712 DOI: 10.1086/512864] [Citation(s) in RCA: 281] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2006] [Accepted: 01/17/2007] [Indexed: 12/26/2022] Open
Abstract
The duplication 17p11.2 syndrome, associated with dup(17)(p11.2p11.2), is a recently recognized syndrome of multiple congenital anomalies and mental retardation and is the first predicted reciprocal microduplication syndrome described--the homologous recombination reciprocal of the Smith-Magenis syndrome (SMS) microdeletion (del(17)(p11.2p11.2)). We previously described seven subjects with dup(17)(p11.2p11.2) and noted their relatively mild phenotype compared with that of individuals with SMS. Here, we molecularly analyzed 28 additional patients, using multiple independent assays, and also report the phenotypic characteristics obtained from extensive multidisciplinary clinical study of a subset of these patients. Whereas the majority of subjects (22 of 35) harbor the homologous recombination reciprocal product of the common SMS microdeletion (~3.7 Mb), 13 subjects (~37%) have nonrecurrent duplications ranging in size from 1.3 to 15.2 Mb. Molecular studies suggest potential mechanistic differences between nonrecurrent duplications and nonrecurrent genomic deletions. Clinical features observed in patients with the common dup(17)(p11.2p11.2) are distinct from those seen with SMS and include infantile hypotonia, failure to thrive, mental retardation, autistic features, sleep apnea, and structural cardiovascular anomalies. We narrow the critical region to a 1.3-Mb genomic interval that contains the dosage-sensitive RAI1 gene. Our results refine the critical region for Potocki-Lupski syndrome, provide information to assist in clinical diagnosis and management, and lend further support for the concept that genomic architecture incites genomic instability.
Collapse
Affiliation(s)
- Lorraine Potocki
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
46
|
McDermott CJ, Shaw PJ. Chapter 17 Hereditary spastic paraparesis. HANDBOOK OF CLINICAL NEUROLOGY 2007; 82:327-352. [PMID: 18808902 DOI: 10.1016/s0072-9752(07)80020-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
|
47
|
Mikesová E, Baránková L, Sakmaryová I, Tatarková I, Seeman P. Quantitative Multiplex Real-Time PCR for Detection of PLP1 Gene Duplications in Pelizaeus–Merzbacher Patients. ACTA ACUST UNITED AC 2006; 10:215-20. [PMID: 17020474 DOI: 10.1089/gte.2006.10.215] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Pelizaeus-Merzbacher disease (PMD) is an X-linked recessive disorder of central nervous system (CNS) myelination typically affecting males. A genomic duplication of variable size at Xq22.2, containing the entire proteolipid protein 1 gene (PLP1), is responsible for approximately 60-70% of PMD cases. The aim of this study was to develop a rapid and robust method for determination of PLP1 gene dosage. We optimized two multiplex real-time quantitative PCR (Q-PCR) assays targeting exons 3 and 6 of the PLP1 gene, and then validated these assays by retrospective analysis of a set of genomic DNAs from 67 previously tested patients and 43 normal controls. Samples were analyzed in multiplex PCR reactions using TaqMan chemistry and the ABI Prism 7000 Sequence Detection System. PLP1 dosage was determined by the relative quantitative comparative threshold cycle method (DeltaDeltaCt) using the human serum albumin gene as the endogenous reference gene. Three clearly non-overlapping ranges of results, corresponding to the presence of one, two, or three PLP1 copies, were detected in both assays. The results were completely concordant with gender and previous PLP1 gene dosage testing based on quantitative fluorescent multiplex PCR and analysis of a dinucleotide polymorphism in the first intron of the PLP1 gene. We conclude that multiplex real-time Q-PCR represents a fast and reliable tool for PLP1 duplication testing in PMD families.
Collapse
Affiliation(s)
- Emilie Mikesová
- Department of Child Neurology, DNA Laboratory, 2nd School of Medicine, Charles University Prague, Prague, Czech Republic.
| | | | | | | | | |
Collapse
|
48
|
Lee JA, Inoue K, Cheung SW, Shaw CA, Stankiewicz P, Lupski JR. Role of genomic architecture in PLP1 duplication causing Pelizaeus-Merzbacher disease. Hum Mol Genet 2006; 15:2250-65. [PMID: 16774974 DOI: 10.1093/hmg/ddl150] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Genomic architecture, higher order structural features of the human genome, can provide molecular substrates for recurrent sub-microscopic chromosomal rearrangements, or may result in genomic instability by forming structures susceptible to DNA double-strand breaks. Pelizaeus-Merzbacher disease (PMD) is a genomic disorder most commonly arising from genomic duplications of the dosage-sensitive proteolipid protein gene (PLP1). Unlike many other genomic disorders that result from non-allelic homologous recombination utilizing flanking low-copy repeats (LCRs) as substrates, generating a common and recurrent rearrangement, the breakpoints of PLP1 duplications have been reported not to cluster, yielding duplicated genomic segments of varying lengths. This suggests a distinct molecular mechanism underlying PLP1 duplication events. To determine whether structural features of the genome also facilitate PLP1 duplication events, we analyzed extensively the genomic architecture of the PLP1 region and defined several novel LCRs (LCR-PMDs). Array comparative genomic hybridization showed that PLP1 duplication sizes differed, but revealed a subgroup of patients with apparently similar PLP1 duplication breakpoints. Pulsed-field gel electrophoresis analysis using probes adjacent to the LCR-PMDs detected unique recombination-specific junction fragments in 12 patients, enabled us to associate the LCR-PMDs with breakpoint regions, and revealed rearrangements inconsistent with simple tandem duplications in four patients. Two-color fluorescence in situ hybridization was consistent with directly oriented duplications. Our study provides evidence that PLP1 duplication events may be stimulated by LCRs, possibly non-homologous pairs at both the proximal and distal breakpoints in some cases, and further supports an alternative role of genomic architecture in rearrangements responsible for genomic disorders.
Collapse
Affiliation(s)
- Jennifer A Lee
- Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Room 604B, Houston, TX 77030, USA
| | | | | | | | | | | |
Collapse
|
49
|
Abstract
Rearrangements of our genome can be responsible for inherited as well as sporadic traits. The analyses of chromosome breakpoints in the proximal short arm of Chromosome 17 (17p) reveal nonallelic homologous recombination (NAHR) as a major mechanism for recurrent rearrangements whereas nonhomologous end-joining (NHEJ) can be responsible for many of the nonrecurrent rearrangements. Genome architectural features consisting of low-copy repeats (LCRs), or segmental duplications, can stimulate and mediate NAHR, and there are hotspots for the crossovers within the LCRs. Rearrangements introduce variation into our genome for selection to act upon and as such serve an evolutionary function analogous to base pair changes. Genomic rearrangements may cause Mendelian diseases, produce complex traits such as behaviors, or represent benign polymorphic changes. The mechanisms by which rearrangements convey phenotypes are diverse and include gene dosage, gene interruption, generation of a fusion gene, position effects, unmasking of recessive coding region mutations (single nucleotide polymorphisms, SNPs, in coding DNA) or other functional SNPs, and perhaps by effects on transvection.
Collapse
Affiliation(s)
- James R Lupski
- Department of Molecular and Human Genetics, Baylor College of Medicine, and at the Texas Children's Hospital, Houston, Texas, United States of America.
| | | |
Collapse
|
50
|
Warshawsky I, Chernova OB, Hübner CA, Stindl R, Henneke M, Gal A, Natowicz MR. Multiplex ligation-dependent probe amplification for rapid detection of proteolipid protein 1 gene duplications and deletions in affected males and carrier females with Pelizaeus-Merzbacher disease. Clin Chem 2006; 52:1267-75. [PMID: 16644873 DOI: 10.1373/clinchem.2006.067967] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
BACKGROUND Pelizaeus-Merzbacher disease is a rare X-linked neurodegenerative disorder caused by sequence variations in the proteolipid protein 1 gene (PLP1). PLP1 gene duplications account for approximately 50%-75% of cases and point variations for approximately 15%-20% of cases; deletions and insertions occur infrequently. We used multiplex ligation-dependent probe amplification (MLPA) to detect PLP1 gene alterations, especially gene duplications and deletions. METHODS We performed MLPA on 102 samples from individuals with diverse PLP1 gene abnormalities and from controls, including 50 samples previously characterized for the PLP1 gene by quantitative PCR but which were anonymized for prior results and sex. RESULTS All males with PLP1 gene duplications (n = 13), 1 male with a triplication, 2 males with whole gene deletions, and all controls (n = 72) were unambiguously assigned to their correct genotype. Of 4 female carriers tested by MLPA and quantitative PCR, 3 were duplication carriers by both methods, and 1 was a triplication carrier by MLPA and a duplication carrier by quantitative PCR. For 1 sample with a partial deletion, MLPA showed exon 3 deleted but PCR showed exons 3 and 4 deleted. Sequence analysis of 2 samples with reduced dosage for exons 3 and 5 revealed point variations overlapping the annealing site for the corresponding MLPA probe. The precision of MLPA analysis was excellent and comparable to or better than quantitative PCR, with CVs of 4.3%-9.8%. CONCLUSIONS MLPA is a rapid and reliable method to determine PLP1 gene copies. Samples with partial PLP1 gene dosage alterations require confirmation with a non-MLPA method.
Collapse
Affiliation(s)
- Ilka Warshawsky
- Department of Clinical Pathology, Cleveland Clinic Foundation, Cleveland, OH 44195, USA.
| | | | | | | | | | | | | |
Collapse
|