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Poot M. Methods of Detection and Mechanisms of Origin of Complex Structural Genome Variations. Methods Mol Biol 2024; 2825:39-65. [PMID: 38913302 DOI: 10.1007/978-1-0716-3946-7_2] [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] [Indexed: 06/25/2024]
Abstract
Based on classical karyotyping, structural genome variations (SVs) have generally been considered to be either "simple" (with one or two breakpoints) or "complex" (with more than two breakpoints). Studying the breakpoints of SVs at nucleotide resolution revealed additional, subtle structural variations, such that even "simple" SVs turned out to be "complex." Genome-wide sequencing methods, such as fosmid and paired-end mapping, short-read and long-read whole genome sequencing, and single-molecule optical mapping, also indicated that the number of SVs per individual was considerably larger than expected from karyotyping and high-resolution chromosomal array-based studies. Interestingly, SVs were detected in studies of cohorts of individuals without clinical phenotypes. The common denominator of all SVs appears to be a failure to accurately repair DNA double-strand breaks (DSBs) or to halt cell cycle progression if DSBs persist. This review discusses the various DSB response mechanisms during the mitotic cell cycle and during meiosis and their regulation. Emphasis is given to the molecular mechanisms involved in the formation of translocations, deletions, duplications, and inversions during or shortly after meiosis I. Recently, CRISPR-Cas9 studies have provided unexpected insights into the formation of translocations and chromothripsis by both breakage-fusion-bridge and micronucleus-dependent mechanisms.
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Affiliation(s)
- Martin Poot
- Department of Human Genetics, University of Wuerzburg, Wuerzburg, Germany
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2
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Rey F, Berardo C, Maghraby E, Mauri A, Messa L, Esposito L, Casili G, Ottolenghi S, Bonaventura E, Cuzzocrea S, Zuccotti G, Tonduti D, Esposito E, Paterniti I, Cereda C, Carelli S. Redox Imbalance in Neurological Disorders in Adults and Children. Antioxidants (Basel) 2023; 12:antiox12040965. [PMID: 37107340 PMCID: PMC10135575 DOI: 10.3390/antiox12040965] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2023] [Revised: 04/03/2023] [Accepted: 04/14/2023] [Indexed: 04/29/2023] Open
Abstract
Oxygen is a central molecule for numerous metabolic and cytophysiological processes, and, indeed, its imbalance can lead to numerous pathological consequences. In the human body, the brain is an aerobic organ and for this reason, it is very sensitive to oxygen equilibrium. The consequences of oxygen imbalance are especially devastating when occurring in this organ. Indeed, oxygen imbalance can lead to hypoxia, hyperoxia, protein misfolding, mitochondria dysfunction, alterations in heme metabolism and neuroinflammation. Consequently, these dysfunctions can cause numerous neurological alterations, both in the pediatric life and in the adult ages. These disorders share numerous common pathways, most of which are consequent to redox imbalance. In this review, we will focus on the dysfunctions present in neurodegenerative disorders (specifically Alzheimer's disease, Parkinson's disease and amyotrophic lateral sclerosis) and pediatric neurological disorders (X-adrenoleukodystrophies, spinal muscular atrophy, mucopolysaccharidoses and Pelizaeus-Merzbacher Disease), highlighting their underlining dysfunction in redox and identifying potential therapeutic strategies.
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Affiliation(s)
- Federica Rey
- Pediatric Clinical Research Center "Romeo ed Enrica Invernizzi", Department of Biomedical and Clinical Sciences, University of Milano, 20157 Milano, Italy
- Center of Functional Genomics and Rare diseases, Department of Pediatrics, Buzzi Children's Hospital, 20154 Milano, Italy
| | - Clarissa Berardo
- Pediatric Clinical Research Center "Romeo ed Enrica Invernizzi", Department of Biomedical and Clinical Sciences, University of Milano, 20157 Milano, Italy
- Center of Functional Genomics and Rare diseases, Department of Pediatrics, Buzzi Children's Hospital, 20154 Milano, Italy
| | - Erika Maghraby
- Pediatric Clinical Research Center "Romeo ed Enrica Invernizzi", Department of Biomedical and Clinical Sciences, University of Milano, 20157 Milano, Italy
- Department of Biology and Biotechnology "L. Spallanzani", University of Pavia, 27100 Pavia, Italy
| | - Alessia Mauri
- Pediatric Clinical Research Center "Romeo ed Enrica Invernizzi", Department of Biomedical and Clinical Sciences, University of Milano, 20157 Milano, Italy
- Center of Functional Genomics and Rare diseases, Department of Pediatrics, Buzzi Children's Hospital, 20154 Milano, Italy
| | - Letizia Messa
- Center of Functional Genomics and Rare diseases, Department of Pediatrics, Buzzi Children's Hospital, 20154 Milano, Italy
- Department of Electronics, Information and Bioengineering (DEIB), Politecnico di Milano, 20133 Milano, Italy
| | - Letizia Esposito
- Pediatric Clinical Research Center "Romeo ed Enrica Invernizzi", Department of Biomedical and Clinical Sciences, University of Milano, 20157 Milano, Italy
- Center of Functional Genomics and Rare diseases, Department of Pediatrics, Buzzi Children's Hospital, 20154 Milano, Italy
| | - Giovanna Casili
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, 98166 Messina, Italy
| | - Sara Ottolenghi
- Department of Medicine and Surgery, University of Milano Bicocca, 20126 Milano, Italy
| | - Eleonora Bonaventura
- Child Neurology Unit, Buzzi Children's Hospital, 20154 Milano, Italy
- Center for Diagnosis and Treatment of Leukodystrophies and Genetic Leukoencephalopathies (COALA), Buzzi Children's Hospital, 20154 Milano, Italy
| | - Salvatore Cuzzocrea
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, 98166 Messina, Italy
| | - Gianvincenzo Zuccotti
- Pediatric Clinical Research Center "Romeo ed Enrica Invernizzi", Department of Biomedical and Clinical Sciences, University of Milano, 20157 Milano, Italy
- Department of Pediatrics, Buzzi Children's Hospital, 20154 Milano, Italy
| | - Davide Tonduti
- Pediatric Clinical Research Center "Romeo ed Enrica Invernizzi", Department of Biomedical and Clinical Sciences, University of Milano, 20157 Milano, Italy
- Child Neurology Unit, Buzzi Children's Hospital, 20154 Milano, Italy
- Center for Diagnosis and Treatment of Leukodystrophies and Genetic Leukoencephalopathies (COALA), Buzzi Children's Hospital, 20154 Milano, Italy
| | - Emanuela Esposito
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, 98166 Messina, Italy
| | - Irene Paterniti
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, 98166 Messina, Italy
| | - Cristina Cereda
- Center of Functional Genomics and Rare diseases, Department of Pediatrics, Buzzi Children's Hospital, 20154 Milano, Italy
| | - Stephana Carelli
- Pediatric Clinical Research Center "Romeo ed Enrica Invernizzi", Department of Biomedical and Clinical Sciences, University of Milano, 20157 Milano, Italy
- Center of Functional Genomics and Rare diseases, Department of Pediatrics, Buzzi Children's Hospital, 20154 Milano, Italy
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Zhu D, Xu L, Zhang Y, Liang G, Wei X, Li L, Jin W, Shang X. Investigation of the mechanism of copy number variations involving the α-globin gene cluster on chromosome 16: two case reports and literature review. Mol Genet Genomics 2023; 298:131-141. [PMID: 36326959 DOI: 10.1007/s00438-022-01968-1] [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: 05/14/2022] [Accepted: 10/25/2022] [Indexed: 11/06/2022]
Abstract
Thalassemia is one of the most common single-gene disorder worldwide. An important genetic cause of thalassemia is copy number variations (CNVs) in the α-globin gene cluster. However, there is no unified summary and discussion on the detailed information and mechanisms of these CNVs. In this study, two novel CNVs, a tandem duplication (αααα159) and deletion (--259), were identified in two Chinese families with thalassemia patients, according to the results of hematologic analysis, routine genetic testing for thalassemia, multiplex ligation-dependent probe amplification (MLPA), next-generation sequencing (NGS) and other molecular methods. Co-inherited with βCD41-42 mutation and --SEA deletion separately, αααα159 and --259 resulted in a patient with β-thalassemia intermedia and a lethal fetus with Hb Bart's hydrops fetalis syndrome, respectively. Next, a literature review was performed to summarize all known CNVs involving the α-globin gene cluster. The molecular structure characteristics of these CNVs were analyzed and the possible mechanism was explored. It is the first time to analyze the generation mechanism of genome arrangements in the α-globin gene cluster systematically.
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Affiliation(s)
- Dina Zhu
- Department of Medical Genetics, School of Basic Medical Sciences, Southern Medical University, Guangzhou, 510515, China
| | - Linlin Xu
- Department of Medical Genetics, School of Basic Medical Sciences, Southern Medical University, Guangzhou, 510515, China
| | - Yanxia Zhang
- Department of Medical Genetics, School of Basic Medical Sciences, Southern Medical University, Guangzhou, 510515, China
| | - Guanxia Liang
- Department of Medical Genetics, School of Basic Medical Sciences, Southern Medical University, Guangzhou, 510515, China
| | - Xiaofeng Wei
- Department of Medical Genetics, School of Basic Medical Sciences, Southern Medical University, Guangzhou, 510515, China
| | - Liyan Li
- Department of Gynecology and Obstetrics, Technology Center of Prenatal Diagnosis and Genetic Diseases Diagnosis, Nanfang Hospital, Southern Medical University, Guangzhou, 510515, China
| | - Wangjie Jin
- Department of Gynecology and Obstetrics, Technology Center of Prenatal Diagnosis and Genetic Diseases Diagnosis, Nanfang Hospital, Southern Medical University, Guangzhou, 510515, China
| | - Xuan Shang
- Department of Medical Genetics, School of Basic Medical Sciences, Southern Medical University, Guangzhou, 510515, China.
- Innovation Center for Diagnostics and Treatment of Thalassemia, Nanfang Hospital, Southern Medical University, Guangzhou, 510515, China.
- Guangdong Provincial Key Laboratory of Single Cell Technology and Application, Guangzhou, 510515, China.
- Experimental Education/Administration Center, School of Basic Medical Science, Southern Medical University, Guangzhou, 510515, China.
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Genes that are Used Together are More Likely to be Fused Together in Evolution by Mutational Mechanisms: A Bioinformatic Test of the Used-Fused Hypothesis. Evol Biol 2023; 50:30-55. [PMID: 36816837 PMCID: PMC9925542 DOI: 10.1007/s11692-022-09579-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2021] [Accepted: 09/11/2022] [Indexed: 12/05/2022]
Abstract
Cases of parallel or recurrent gene fusions in evolution as well as in genetic disease and cancer are difficult to explain, because unlike point mutations, they can require the repetition of a similar configuration of multiple breakpoints rather than the repetition of a single point mutation. The used-together-fused-together hypothesis holds that genes that are used together repeatedly and persistently in a specific context are more likely to undergo fusion mutation in the course of evolution for mechanistic reasons. This hypothesis offers to explain gene fusion in both evolution and disease under one umbrella. Using bioinformatic data, we tested this hypothesis against alternatives, including that all gene pairs can fuse by random mutation, but among pairs thus fused, those that had interacted previously are more likely to be favored by selection. Results show that across multiple measures of gene interaction, human genes whose orthologs are fused in one or more species are more likely to interact with each other than random pairs of genes of the same genomic distance between pair members; that an overlap exists between genes that fused in the course of evolution in non-human species and genes that undergo fusion in human cancers; and that across six primate species studied, fusions predominate over fissions and exhibit substantial evolutionary parallelism. Together, these results support the used-together-fused-together hypothesis over its alternatives. Multiple implications are discussed, including the relevance of mutational mechanisms to the evolution of genome organization, to the distribution of fitness effects of mutation, to evolutionary parallelism and more. Supplementary Information The online version contains supplementary material available at 10.1007/s11692-022-09579-9.
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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: 5] [Impact Index Per Article: 2.5] [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.
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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.)
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Zhang S, Xu H, Tian Y, Liu D, Hou X, Zeng B, Chen B, Liu H, Li R, Li X, Zuo B, Tang R, Tang W. High Genetic Heterogeneity in Chinese Patients With Waardenburg Syndrome Revealed by Next-Generation Sequencing. Front Genet 2021; 12:643546. [PMID: 34149797 PMCID: PMC8212959 DOI: 10.3389/fgene.2021.643546] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Accepted: 04/23/2021] [Indexed: 01/08/2023] Open
Abstract
Objective This study aimed to explore the genetic causes of probands who were diagnosed with Waardenburg syndrome (WS) or congenital sensorineural hearing loss. Methods A detailed physical and audiological examinations were carried out to make an accurate diagnosis of 14 patients from seven unrelated families. We performed whole-exome sequencing in probands to detect the potential genetic causes and further validated them by Sanger sequencing in the probands and their family members. Results The genetic causes for all 14 patients with WS or congenital sensorineural hearing loss were identified. A total of seven heterozygous variants including c.1459C > T, c.123del, and c.959-409_1173+3402del of PAX3 gene (NM_181459.4), c.198_262del and c.529_556del of SOX10 gene (NM_006941.4), and c.731G > A and c.970dup of MITF gene (NM_000248.3) were found for the first time. Of these mutations, we had confirmed two (c.1459C > T and c.970dup) are de novo by Sanger sequencing of variants in the probands and their parents. Conclusion We revealed a total of seven novel mutations in PAX3, SOX10, and MITF, which underlie the pathogenesis of WS. The clinical and genetic characterization of these families with WS elucidated high heterogeneity in Chinese patients with WS. This study expands the database of PAX3, SOX10, and MITF mutations and improves our understanding of the causes of WS.
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Affiliation(s)
- Sen Zhang
- School of Basic Medical Sciences, Zhengzhou University, Zhengzhou, China
| | - Hongen Xu
- Precision Medicine Center, Academy of Medical Science, Zhengzhou University, Zhengzhou, China.,The Second Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Yongan Tian
- BGI College, Zhengzhou University, Zhengzhou, China
| | - Danhua Liu
- The Second Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Xinyue Hou
- School of Basic Medical Sciences, Zhengzhou University, Zhengzhou, China
| | - Beiping Zeng
- BGI College, Zhengzhou University, Zhengzhou, China
| | - Bei Chen
- Department of Otology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Huanfei Liu
- Precision Medicine Center, Academy of Medical Science, Zhengzhou University, Zhengzhou, China
| | - Ruijun Li
- Precision Medicine Center, Academy of Medical Science, Zhengzhou University, Zhengzhou, China
| | - Xiaohua Li
- Department of Otology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Bin Zuo
- Department of Otology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Ryan Tang
- Johns Hopkins University, Maryland, MD, United States
| | - Wenxue Tang
- Precision Medicine Center, Academy of Medical Science, Zhengzhou University, Zhengzhou, China.,The Second Affiliated Hospital of Zhengzhou University, Zhengzhou, China.,Henan Institute of Medical and Pharmaceutical Sciences, Zhengzhou University, Zhengzhou, China
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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: 13] [Impact Index Per Article: 3.3] [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.
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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
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Chanchani SR, Xie H, Sekhon G, Melikishvili AM, Moyer Harasink S, Pall H, Giampietro PF. A male infant with Xq22.2q22.3 duplication containing PLP1 and MID2. Mol Genet Genomic Med 2020; 8:e1078. [PMID: 31951325 PMCID: PMC7057127 DOI: 10.1002/mgg3.1078] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Revised: 10/26/2019] [Accepted: 11/11/2019] [Indexed: 12/24/2022] Open
Abstract
Background The Xq22.2 q23 is a complex genomic region which includes the genes MID2 and PLP1 associated with FG syndrome 5 and Pelizaeus–Merzbacher disease, respectively. There is limited information regarding the clinical outcomes observed in patients with deletions within this region. Methods We report on a male infant with intrauterine growth retardation (IUGR) who developed head titubation and spasticity during his postnatal hospital course. Results Chromosome microarray revealed a 6.7 Mb interstitial duplication of Xq22.2q22.3. Fluorescence in situ hybridization showed that the patient's mother also possessed the identical duplication in the Xq22.3q22.3 region. Among the 34 OMIM genes in this interval, the duplication of the PLP1 (OMIM# 300401) and MID2 (OMIM# 300204) appears to be the most significant contributors to the patient's clinical features. Mutations and duplications of PLP1 are associated with X‐linked recessive Pelizaeus–Merzbacher disease (PMD). A single case of a Xq22.3 duplication including the MID2 has been reported in boy with features of FG syndrome. However, our patient's clinical features are not consistent with the FG syndrome phenotype. Conclusion Our patient's clinical features appear to be influenced by the PLP1 duplication but the clinical effect of other dosage sensitive genes influencing brain development cannot be ruled out.
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Affiliation(s)
- Swati R Chanchani
- Department of Pediatrics St. Christopher's Hospital for Children, Drexel University College of Medicine, Philadelphia, PA, USA
| | - Hongyan Xie
- Tricore Reference Laboratory, Albuquerque, NM, USA
| | | | | | - Sue Moyer Harasink
- Department of Pediatrics St. Christopher's Hospital for Children, Drexel University College of Medicine, Philadelphia, PA, USA
| | - Harpreet Pall
- Department of Pediatrics St. Christopher's Hospital for Children, Drexel University College of Medicine, Philadelphia, PA, USA
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Distinct patterns of complex rearrangements and a mutational signature of microhomeology are frequently observed in PLP1 copy number gain structural variants. Genome Med 2019; 11:80. [PMID: 31818324 PMCID: PMC6902434 DOI: 10.1186/s13073-019-0676-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2019] [Accepted: 10/10/2019] [Indexed: 01/05/2023] Open
Abstract
BACKGROUND We investigated the features of the genomic rearrangements in a cohort of 50 male individuals with proteolipid protein 1 (PLP1) copy number gain events who were ascertained with Pelizaeus-Merzbacher disease (PMD; MIM: 312080). We then compared our new data to previous structural variant mutagenesis studies involving the Xq22 region of the human genome. The aggregate data from 159 sequenced join-points (discontinuous sequences in the reference genome that are joined during the rearrangement process) were studied. Analysis of these data from 150 individuals enabled the spectrum and relative distribution of the underlying genomic mutational signatures to be delineated. METHODS Genomic rearrangements in PMD individuals with PLP1 copy number gain events were investigated by high-density customized array or clinical chromosomal microarray analysis and breakpoint junction sequence analysis. RESULTS High-density customized array showed that the majority of cases (33/50; ~ 66%) present with single duplications, although complex genomic rearrangements (CGRs) are also frequent (17/50; ~ 34%). Breakpoint mapping to nucleotide resolution revealed further previously unknown structural and sequence complexities, even in single duplications. Meta-analysis of all studied rearrangements that occur at the PLP1 locus showed that single duplications were found in ~ 54% of individuals and that, among all CGR cases, triplication flanked by duplications is the most frequent CGR array CGH pattern observed. Importantly, in ~ 32% of join-points, there is evidence for a mutational signature of microhomeology (highly similar yet imperfect sequence matches). CONCLUSIONS These data reveal a high frequency of CGRs at the PLP1 locus and support the assertion that replication-based mechanisms are prominent contributors to the formation of CGRs at Xq22. We propose that microhomeology can facilitate template switching, by stabilizing strand annealing of the primer using W-C base complementarity, and is a mutational signature for replicative repair.
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Hijazi H, Coelho FS, Gonzaga-Jauregui C, Bernardini L, Mar SS, Manning MA, Hanson-Kahn A, Naidu S, Srivastava S, Lee JA, Jones JR, Friez MJ, Alberico T, Torres B, Fang P, Cheung SW, Song X, Davis-Williams A, Jornlin C, Wight PA, Patyal P, Taube J, Poretti A, Inoue K, Zhang F, Pehlivan D, Carvalho CMB, Hobson GM, Lupski JR. Xq22 deletions and correlation with distinct neurological disease traits in females: Further evidence for a contiguous gene syndrome. Hum Mutat 2019; 41:150-168. [PMID: 31448840 DOI: 10.1002/humu.23902] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Revised: 08/14/2019] [Accepted: 08/22/2019] [Indexed: 01/24/2023]
Abstract
Xq22 deletions that encompass PLP1 (Xq22-PLP1-DEL) are notable for variable expressivity of neurological disease traits in females ranging from a mild late-onset form of spastic paraplegia type 2 (MIM# 312920), sometimes associated with skewed X-inactivation, to an early-onset neurological disease trait (EONDT) of severe developmental delay, intellectual disability, and behavioral abnormalities. Size and gene content of Xq22-PLP1-DEL vary and were proposed as potential molecular etiologies underlying variable expressivity in carrier females where two smallest regions of overlap (SROs) were suggested to influence disease. We ascertained a cohort of eight unrelated patients harboring Xq22-PLP1-DEL and performed high-density array comparative genomic hybridization and breakpoint-junction sequencing. Molecular characterization of Xq22-PLP1-DEL from 17 cases (eight herein and nine published) revealed an overrepresentation of breakpoints that reside within repeats (11/17, ~65%) and the clustering of ~47% of proximal breakpoints in a genomic instability hotspot with characteristic non-B DNA density. These findings implicate a potential role for genomic architecture in stimulating the formation of Xq22-PLP1-DEL. The correlation of Xq22-PLP1-DEL gene content with neurological disease trait in female cases enabled refinement of the associated SROs to a single genomic interval containing six genes. Our data support the hypothesis that genes contiguous to PLP1 contribute to EONDT.
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Affiliation(s)
- Hadia Hijazi
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas
| | - Fernanda S Coelho
- Programa de Pós-Graduação em Genética Departmento de Biologia Geral, UFMG, Belo Horizonte, Minas Gerais, Brazil.,Instituto René Rachou, FIOCRUZ, Belo Horizonte, Minas Gerais, Brazil
| | | | - Laura Bernardini
- Medical Genetics Division, IRCCS "Casa Sollievo della Sofferenza" Foundation, San Giovanni Rotondo (FG), Italy
| | - Soe S Mar
- Department of Neurology, Washington University School of Medicine, St. Louis, Missouri
| | - Melanie A Manning
- Division of Medical Genetics, Department of Pediatrics, Stanford University School of Medicine, Palo Alto, California.,Department of Pathology, Stanford University School of Medicine, Palo Alto, California
| | - Andrea Hanson-Kahn
- Division of Medical Genetics, Department of Pediatrics, Stanford University School of Medicine, Palo Alto, California.,Department of Genetics, Stanford University School of Medicine, Palo Alto, California
| | - SakkuBai Naidu
- Departments of Neurology and Pediatrics, Johns Hopkins University School of Medicine, Baltimore, Maryland.,Department of Neurogenetics, Kennedy Krieger Institute, Baltimore, Maryland
| | | | - Jennifer A Lee
- Molecular Diagnostic Laboratory, Greenwood Genetic Center, Greenwood, South Carolina
| | - Julie R Jones
- Molecular Diagnostic Laboratory, Greenwood Genetic Center, Greenwood, South Carolina
| | - Michael J Friez
- Molecular Diagnostic Laboratory, Greenwood Genetic Center, Greenwood, South Carolina
| | - Thomas Alberico
- Nemours Biomedical Research, Nemours/Alfred I. duPont Hospital for Children, Wilmington, Delaware
| | - Barbara Torres
- Medical Genetics Division, IRCCS "Casa Sollievo della Sofferenza" Foundation, San Giovanni Rotondo (FG), Italy
| | - Ping Fang
- Clinical Genomics, WuXi NextCODE, Cambridge, Massachusetts
| | - Sau Wai Cheung
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas
| | - Xiaofei Song
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas
| | - Angelique Davis-Williams
- Nemours Biomedical Research, Nemours/Alfred I. duPont Hospital for Children, Wilmington, Delaware
| | - Carly Jornlin
- Nemours Biomedical Research, Nemours/Alfred I. duPont Hospital for Children, Wilmington, Delaware
| | - Patricia A Wight
- Department of Physiology and Biophysics, College of Medicine, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Pankaj Patyal
- Department of Physiology and Biophysics, College of Medicine, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Jennifer Taube
- Nemours Biomedical Research, Nemours/Alfred I. duPont Hospital for Children, Wilmington, Delaware
| | - Andrea Poretti
- Departments of Neurology and Pediatrics, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Ken Inoue
- Department of Mental Retardation and Birth Defect Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Kodaira, Japan
| | - Feng Zhang
- State Key Laboratory of Genetic Engineering at School of Life Sciences, Obstetrics and Gynecology Hospital, Institute of Reproduction and Development, Fudan University, Shanghai, China
| | - Davut Pehlivan
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas.,Section of Neurology, Department of Pediatrics, Baylor College of Medicine, Houston, Texas
| | - Claudia M B Carvalho
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas
| | - Grace M Hobson
- Nemours Biomedical Research, Nemours/Alfred I. duPont Hospital for Children, Wilmington, Delaware
| | - James R Lupski
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas.,Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas.,Department of Pediatrics, Baylor College of Medicine, Houston, Texas.,Texas Children's Hospital, Houston, Texas
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11
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Pang D, Shang X, Cai D, Zhu F, Cheng Y, Zhong J, Yi S, Zhang Q, Xu X. Thalassaemia intermedia caused by coinheritance of a β‐thalassaemia mutation and a
de novo
duplication of α‐globin genes in the paternal allele. Br J Haematol 2019; 186:620-624. [DOI: 10.1111/bjh.15958] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2019] [Accepted: 03/05/2019] [Indexed: 12/11/2022]
Affiliation(s)
- Dejian Pang
- Department of Medical Genetics School of Basic Medical Sciences Southern Medical UniversityGuangzhou Guangdong China
| | - Xuan Shang
- Department of Medical Genetics School of Basic Medical Sciences Southern Medical UniversityGuangzhou Guangdong China
- Guangdong Genetics Testing Engineering Research CentreGuangzhou Guangdong China
- Guangdong Provincial Key Laboratory of Single Cell Technology and Application Guangzhou GuangdongChina
| | - Decheng Cai
- Department of Medical Genetics School of Basic Medical Sciences Southern Medical UniversityGuangzhou Guangdong China
| | - Fei Zhu
- Department of Medical Genetics School of Basic Medical Sciences Southern Medical UniversityGuangzhou Guangdong China
| | - Yi Cheng
- Department of Medical Genetics School of Basic Medical Sciences Southern Medical UniversityGuangzhou Guangdong China
| | - Jianmei Zhong
- Department of Medical Genetics School of Basic Medical Sciences Southern Medical UniversityGuangzhou Guangdong China
| | - Sheng Yi
- Prenatal Diagnostic Centre Guangxi Zhuang Autonomous Region Women and Children Care Hospital Nanning Guangxi China
| | - Qianqian Zhang
- Department of Medical Genetics School of Basic Medical Sciences Southern Medical UniversityGuangzhou Guangdong China
| | - Xiangmin Xu
- Department of Medical Genetics School of Basic Medical Sciences Southern Medical UniversityGuangzhou Guangdong China
- Guangdong Genetics Testing Engineering Research CentreGuangzhou Guangdong China
- Guangdong Provincial Key Laboratory of Single Cell Technology and Application Guangzhou GuangdongChina
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12
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Xie X, Chen C, Liang Q, Wu X, Wang X, Wu W, Ding Q. Characterization of two large duplications of
F9
associated with mild and severe haemophilia B, respectively. Haemophilia 2019; 25:475-483. [PMID: 30866119 DOI: 10.1111/hae.13704] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Revised: 09/06/2018] [Accepted: 01/23/2019] [Indexed: 02/01/2023]
Affiliation(s)
- Xiaoling Xie
- State Key Laboratory of Medical Genomics, Shanghai Institute of Hematology, Ruijin Hospital Shanghai Jiaotong University School of Medicine Shanghai China
| | - Changming Chen
- Department of Laboratory Medicine, Ruijin Hospital Shanghai Jiaotong University School of Medicine Shanghai China
| | - Qian Liang
- Department of Laboratory Medicine, Ruijin Hospital Shanghai Jiaotong University School of Medicine Shanghai China
| | - Xi Wu
- Department of Laboratory Medicine, Ruijin Hospital Shanghai Jiaotong University School of Medicine Shanghai China
| | - Xuefeng Wang
- Department of Laboratory Medicine, Ruijin Hospital Shanghai Jiaotong University School of Medicine Shanghai China
- Collaborative Innovation Center of Hematology Shanghai Jiaotong University School of Medicine Shanghai China
| | - Wenman Wu
- Collaborative Innovation Center of Hematology Shanghai Jiaotong University School of Medicine Shanghai China
- Faculty of Medical Laboratory Science, Ruijin Hospital Shanghai Jiaotong University School of Medicine Shanghai China
| | - Qiulan Ding
- Department of Laboratory Medicine, Ruijin Hospital Shanghai Jiaotong University School of Medicine Shanghai China
- Collaborative Innovation Center of Hematology Shanghai Jiaotong University School of Medicine Shanghai China
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13
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Auditory function in Pelizaeus–Merzbacher disease. J Neurol 2018; 265:1580-1589. [DOI: 10.1007/s00415-018-8884-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Revised: 04/23/2018] [Accepted: 04/24/2018] [Indexed: 10/17/2022]
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14
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Osório MJ, Goldman SA. Neurogenetics of Pelizaeus-Merzbacher disease. HANDBOOK OF CLINICAL NEUROLOGY 2018; 148:701-722. [PMID: 29478609 DOI: 10.1016/b978-0-444-64076-5.00045-4] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Pelizaeus-Merzbacher disease (PMD) is an X-linked disorder caused by mutations in the PLP1 gene, which encodes the proteolipid protein of myelinating oligodendroglia. PMD exhibits phenotypic variability that reflects its considerable genotypic heterogeneity, but all forms of the disease result in central hypomyelination associated with early neurologic dysfunction, progressive deterioration, and ultimately death. PMD has been classified into three major subtypes, according to the age of presentation: connatal PMD, classic PMD, and transitional PMD, combining features of both connatal and classic forms. Two other less severe phenotypes were subsequently described, including the spastic paraplegia syndrome and PLP1-null disease. These disorders may be associated with duplications, as well as with point, missense, and null mutations within the PLP1 gene. A number of clinically similar Pelizaeus-Merzbacher-like disorders (PMLD) are considered in the differential diagnosis of PMD, the most prominent of which is PMLD-1, caused by misexpression of the GJC2 gene encoding connexin-47. No effective therapy for PMD exists. Yet, as a relatively pure central nervous system hypomyelinating disorder, with limited involvement of the peripheral nervous system and little attendant neuronal pathology, PMD is an attractive therapeutic target for neural stem cell and glial progenitor cell transplantation, efforts at which are now underway in a number of centers internationally.
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Affiliation(s)
- M Joana Osório
- Center for Translational Neuromedicine and Department of Neurology, University of Rochester Medical Center, Rochester, NY, United States; Center for Translational Neuromedicine, University of Copenhagen Faculty of Health and Medical Sciences, Copenhagen, Denmark
| | - Steven A Goldman
- Center for Translational Neuromedicine and Department of Neurology, University of Rochester Medical Center, Rochester, NY, United States; Center for Translational Neuromedicine, University of Copenhagen Faculty of Health and Medical Sciences, Copenhagen, Denmark.
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15
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Xu Y, Wang H, Xiao B, Wei W, Liu Y, Ye H, Ying X, Chen Y, Liu X, Ji X, Sun Y. Novel noncontiguous duplications identified with a comprehensive mutation analysis in the DMD gene by DMD gene-targeted sequencing. Gene 2017; 645:113-118. [PMID: 29273555 DOI: 10.1016/j.gene.2017.12.037] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Revised: 12/01/2017] [Accepted: 12/18/2017] [Indexed: 12/14/2022]
Abstract
Genomic rearrangements, such as intragenic deletions and duplications, are the most prevalent types of mutation in the DMD gene, and DMD mutations underlie Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD). Using multiplex ligation dependent probe amplification (MLPA) and DMD gene-targeted sequencing, we performed a molecular characterization of two cases of complex noncontiguous duplication rearrangements that involved inverted duplications. The breakpoint sequences were analyzed to investigate the mechanisms of the rearrangement. The two cases shared the same duplication events (Dup-nml-Dup/inv), and both involved microhomology and small insertions at the breakpoints. Additionally, in case 1, SNP sequencing results indicated that the de novo duplication mutation arose in the allele that originated from the grandfather. This study has identified a novel type of DMD complex rearrangement and provides insight into the molecular basis of this genomic rearrangement.
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Affiliation(s)
- Yan Xu
- Center for Clinical Genetics, Xinhua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China; Department of Genetics, Shanghai Institute of Pediatric Research, Shanghai, China
| | - Huanhuan Wang
- Center for Clinical Genetics, Xinhua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China; Department of Genetics, Shanghai Institute of Pediatric Research, Shanghai, China
| | - Bing Xiao
- Center for Clinical Genetics, Xinhua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China; Department of Genetics, Shanghai Institute of Pediatric Research, Shanghai, China
| | - Wei Wei
- Center for Clinical Genetics, Xinhua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China; Department of Genetics, Shanghai Institute of Pediatric Research, Shanghai, China
| | - Yu Liu
- Center for Clinical Genetics, Xinhua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China; Department of Genetics, Shanghai Institute of Pediatric Research, Shanghai, China
| | - Hui Ye
- Center for Clinical Genetics, Xinhua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China; Department of Genetics, Shanghai Institute of Pediatric Research, Shanghai, China
| | - Xiaomin Ying
- Center for Clinical Genetics, Xinhua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China; Department of Genetics, Shanghai Institute of Pediatric Research, Shanghai, China
| | - Yingwei Chen
- Center for Clinical Genetics, Xinhua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Xiaoqing Liu
- Department of Genetics, Shanghai Institute of Pediatric Research, Shanghai, China; Department of Pediatric Neurology, Xinhua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Xing Ji
- Center for Clinical Genetics, Xinhua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China; Department of Genetics, Shanghai Institute of Pediatric Research, Shanghai, China.
| | - Yu Sun
- Center for Clinical Genetics, Xinhua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China; Department of Genetics, Shanghai Institute of Pediatric Research, Shanghai, China.
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16
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Zhang L, Wang J, Zhang C, Li D, Carvalho CM, Ji H, Xiao J, Wu Y, Zhou W, Wang H, Jin L, Luo Y, Wu X, Lupski JR, Zhang F, Jiang Y. Efficient CNV breakpoint analysis reveals unexpected structural complexity and correlation of dosage-sensitive genes with clinical severity in genomic disorders. Hum Mol Genet 2017; 26:1927-1941. [PMID: 28334874 PMCID: PMC6075079 DOI: 10.1093/hmg/ddx102] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2017] [Revised: 03/08/2017] [Accepted: 03/10/2017] [Indexed: 01/13/2023] Open
Abstract
Genomic disorders are the clinical conditions manifested by submicroscopic genomic rearrangements including copy number variants (CNVs). The CNVs can be identified by array-based comparative genomic hybridization (aCGH), the most commonly used technology for molecular diagnostics of genomic disorders. However, clinical aCGH only informs CNVs in the probe-interrogated regions. Neither orientational information nor the resulting genomic rearrangement structure is provided, which is a key to uncovering mutational and pathogenic mechanisms underlying genomic disorders. Long-range polymerase chain reaction (PCR) is a traditional approach to obtain CNV breakpoint junction, but this method is inefficient when challenged by structural complexity such as often found at the PLP1 locus in association with Pelizaeus-Merzbacher disease (PMD). Here we introduced 'capture and single-molecule real-time sequencing' (cap-SMRT-seq) and newly developed 'asymmetry linker-mediated nested PCR walking' (ALN-walking) for CNV breakpoint sequencing in 49 subjects with PMD-associated CNVs. Remarkably, 29 (94%) of the 31 CNV breakpoint junctions unobtainable by conventional long-range PCR were resolved by cap-SMRT-seq and ALN-walking. Notably, unexpected CNV complexities, including inter-chromosomal rearrangements that cannot be resolved by aCGH, were revealed by efficient breakpoint sequencing. These sequence-based structures of PMD-associated CNVs further support the role of DNA replicative mechanisms in CNV mutagenesis, and facilitate genotype-phenotype correlation studies. Intriguingly, the lengths of gained segments by CNVs are strongly correlated with clinical severity in PMD, potentially reflecting the functional contribution of other dosage-sensitive genes besides PLP1. Our study provides new efficient experimental approaches (especially ALN-walking) for CNV breakpoint sequencing and highlights their importance in uncovering CNV mutagenesis and pathogenesis in genomic disorders.
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Affiliation(s)
- Ling Zhang
- Obstetrics and Gynecology Hospital, State Key Laboratory of Genetic Engineering at School of Life Sciences, Institute of Reproduction and Development, Fudan University, Shanghai 200011, China
- Key Laboratory of Reproduction Regulation of NPFPC, Collaborative Innovation Center of Genetics and Development, Fudan University, Shanghai 200032, China
- Shanghai Key Laboratory of Female Reproductive Endocrine Related Diseases, Shanghai 200011, China
| | - Jingmin Wang
- Department of Pediatrics, Peking University First Hospital, Beijing 100034, China
| | - Cheng Zhang
- Obstetrics and Gynecology Hospital, State Key Laboratory of Genetic Engineering at School of Life Sciences, Institute of Reproduction and Development, Fudan University, Shanghai 200011, China
| | - Dongxiao Li
- Department of Pediatrics, Peking University First Hospital, Beijing 100034, China
| | - Claudia M.B. Carvalho
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Haoran Ji
- Department of Pediatrics, Peking University First Hospital, Beijing 100034, China
| | - Jianqiu Xiao
- Obstetrics and Gynecology Hospital, State Key Laboratory of Genetic Engineering at School of Life Sciences, Institute of Reproduction and Development, Fudan University, Shanghai 200011, China
| | - Ye Wu
- Department of Pediatrics, Peking University First Hospital, Beijing 100034, China
| | - Weichen Zhou
- Obstetrics and Gynecology Hospital, State Key Laboratory of Genetic Engineering at School of Life Sciences, Institute of Reproduction and Development, Fudan University, Shanghai 200011, China
| | - Hongyan Wang
- Obstetrics and Gynecology Hospital, State Key Laboratory of Genetic Engineering at School of Life Sciences, Institute of Reproduction and Development, Fudan University, Shanghai 200011, China
- Key Laboratory of Reproduction Regulation of NPFPC, Collaborative Innovation Center of Genetics and Development, Fudan University, Shanghai 200032, China
- Shanghai Key Laboratory of Female Reproductive Endocrine Related Diseases, Shanghai 200011, China
| | - Li Jin
- Obstetrics and Gynecology Hospital, State Key Laboratory of Genetic Engineering at School of Life Sciences, Institute of Reproduction and Development, Fudan University, Shanghai 200011, China
- Key Laboratory of Reproduction Regulation of NPFPC, Collaborative Innovation Center of Genetics and Development, Fudan University, Shanghai 200032, China
| | - Yang Luo
- MOE Key Laboratory of Medical Cell Biology, The Research Center for Medical Genomics, College of Basic Medical Science, China Medical University, Shenyang 110001, China
| | - Xiru Wu
- Department of Pediatrics, Peking University First Hospital, Beijing 100034, China
| | - James R. Lupski
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
- Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030, USA
- Texas Children’s Hospital, Houston, TX 77030, USA
| | - Feng Zhang
- Obstetrics and Gynecology Hospital, State Key Laboratory of Genetic Engineering at School of Life Sciences, Institute of Reproduction and Development, Fudan University, Shanghai 200011, China
- Key Laboratory of Reproduction Regulation of NPFPC, Collaborative Innovation Center of Genetics and Development, Fudan University, Shanghai 200032, China
- Shanghai Key Laboratory of Female Reproductive Endocrine Related Diseases, Shanghai 200011, China
| | - Yuwu Jiang
- Department of Pediatrics, Peking University First Hospital, Beijing 100034, China
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17
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Rebuzzini P, Zuccotti M, Redi CA, Garagna S. Achilles' heel of pluripotent stem cells: genetic, genomic and epigenetic variations during prolonged culture. Cell Mol Life Sci 2016; 73:2453-66. [PMID: 26961132 PMCID: PMC11108315 DOI: 10.1007/s00018-016-2171-8] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Revised: 01/28/2016] [Accepted: 02/25/2016] [Indexed: 12/12/2022]
Abstract
Pluripotent stem cells differentiate into almost any specialized adult cell type of an organism. PSCs can be derived either from the inner cell mass of a blastocyst-giving rise to embryonic stem cells-or after reprogramming of somatic terminally differentiated cells to obtain ES-like cells, named induced pluripotent stem cells. The potential use of these cells in the clinic, for investigating in vitro early embryonic development or for screening the effects of new drugs or xenobiotics, depends on capability to maintain their genome integrity during prolonged culture and differentiation. Both human and mouse PSCs are prone to genomic and (epi)genetic instability during in vitro culture, a feature that seriously limits their real potential use. Culture-induced variations of specific chromosomes or genes, are almost all unpredictable and, as a whole, differ among independent cell lines. They may arise at different culture passages, suggesting the absence of a safe passage number maintaining genome integrity and rendering the control of genomic stability mandatory since the very early culture passages. The present review highlights the urgency for further studies on the mechanisms involved in determining (epi)genetic and chromosome instability, exploiting the knowledge acquired earlier on other cell types.
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Affiliation(s)
- Paola Rebuzzini
- Laboratorio di Biologia dello Sviluppo, Dipartimento di Biologia e Biotecnologie 'Lazzaro Spallanzani', Università degli Studi di Pavia, Via Ferrata 9, 27100, Pavia, Italy.
- Center for Health Technologies (C.H.T.), Università degli Studi di Pavia, Via Ferrata 1, Pavia, Italy.
| | - Maurizio Zuccotti
- Unita' di Anatomia, Istologia ed Embriologia, Dipartimento di Scienze Biomediche, Biotecnologiche e Traslazionali (S.BI.BI.T.), Università degli Studi di Parma, Via Volturno 39, 43100, Parma, Italy.
| | - Carlo Alberto Redi
- Laboratorio di Biologia dello Sviluppo, Dipartimento di Biologia e Biotecnologie 'Lazzaro Spallanzani', Università degli Studi di Pavia, Via Ferrata 9, 27100, Pavia, Italy
- Center for Health Technologies (C.H.T.), Università degli Studi di Pavia, Via Ferrata 1, Pavia, Italy
- Fondazione I.R.C.C.S. Policlinico San Matteo, Piazzale Golgi, 19, 27100, Pavia, Italy
| | - Silvia Garagna
- Laboratorio di Biologia dello Sviluppo, Dipartimento di Biologia e Biotecnologie 'Lazzaro Spallanzani', Università degli Studi di Pavia, Via Ferrata 9, 27100, Pavia, Italy.
- Center for Health Technologies (C.H.T.), Università degli Studi di Pavia, Via Ferrata 1, Pavia, Italy.
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18
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Carvalho CMB, Lupski JR. Mechanisms underlying structural variant formation in genomic disorders. Nat Rev Genet 2016; 17:224-38. [PMID: 26924765 DOI: 10.1038/nrg.2015.25] [Citation(s) in RCA: 414] [Impact Index Per Article: 51.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
With the recent burst of technological developments in genomics, and the clinical implementation of genome-wide assays, our understanding of the molecular basis of genomic disorders, specifically the contribution of structural variation to disease burden, is evolving quickly. Ongoing studies have revealed a ubiquitous role for genome architecture in the formation of structural variants at a given locus, both in DNA recombination-based processes and in replication-based processes. These reports showcase the influence of repeat sequences on genomic stability and structural variant complexity and also highlight the tremendous plasticity and dynamic nature of our genome in evolution, health and disease susceptibility.
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Affiliation(s)
- Claudia M B Carvalho
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77030, USA.,Centro de Pesquisas René Rachou - FIOCRUZ, Belo Horizonte, MG 30190-002, Brazil
| | - James R Lupski
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77030, USA.,Department of Pediatrics, Baylor College of Medicine, Houston, Texas 77030, USA.,Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas 77030, USA.,Texas Children's Hospital, Houston, Texas 77030, USA
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19
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Kraus A, Michalak M. Endoplasmic reticulum quality control and dysmyelination. Biomol Concepts 2015; 2:261-74. [PMID: 25962034 DOI: 10.1515/bmc.2011.028] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Dysmyelination contributes to several human diseases including multiple sclerosis, Charcot-Marie-Tooth, leukodystrophies, and schizophrenia and can result in serious neurological disability. Properly formed, compacted myelin sheaths are required for appropriate nerve conduction velocities and the health and survival of neurons. Many different molecular mechanisms contribute to dysmyelination and many of these mechanisms originate at the level of the endoplasmic reticulum. The endoplasmic reticulum is a critical organelle for myelin biosynthesis and maintenance as the site of myelin protein folding quality control, Ca2+ homeostasis, cholesterol biosynthesis, and modulation of cellular stress. This review paper highlights the role of the endoplasmic reticulum and its resident molecules as an upstream and dynamic contributor to myelin and myelin pathologies.
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20
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Ambroziak W, Koziorowski D, Duszyc K, Górka-Skoczylas P, Potulska-Chromik A, Sławek J, Hoffman-Zacharska D. Genomic instability in the PARK2 locus is associated with Parkinson's disease. J Appl Genet 2015; 56:451-461. [PMID: 25833766 PMCID: PMC4617850 DOI: 10.1007/s13353-015-0282-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2014] [Revised: 03/05/2015] [Accepted: 03/05/2015] [Indexed: 12/01/2022]
Abstract
Parkinson’s disease (PD) is a common neurodegenerative disorder affecting mostly elderly people, although there is a group of patients developing so-called early-onset PD (EOPD). Mutations in the PARK2 gene are a common cause of autosomal recessive EOPD. PARK2 belongs to the family of extremely large human genes which are often localised in genomic common fragile sites (CFSs) and exhibit gross instability. PARK2 is located in the centre of FRA6E, the third most mutation-susceptible CFS of the human genome. The gene encompasses a region of 1.3 Mbp and, among its mutations, large rearrangements of single or multiple exons account for around 50 %. We performed an analysis of the PARK2 gene in a group of 344 PD patients with EOPD and classical form of the disease. Copy number changes were first identified using multiplex ligation probe amplification (MLPA), with their ranges characterised by array comparative genomic hybridisation (aCGH). Exact breakpoints were mapped using direct sequencing. Rearrangements were found in eight subjects, including five deletions and three duplications. Rearrangements were mostly non-recurrent and no repetitive sequences or extended homologies were identified in the regions flanking breakpoint junctions. However, in most cases, 1–3 bp microhomologies were present, strongly suggesting that microhomology-mediated mechanisms, specifically non-homologous end joining (NHEJ) and fork stalling and template switching (FoSTeS)/microhomology-mediated break-induced replication (MMBIR), are predominantly involved in the rearrangement processes in this genomic region.
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Affiliation(s)
- Wojciech Ambroziak
- Department of Medical Genetics, Institute of Mother and Child, Kasprzaka 17A, 01-211, Warsaw, Poland.,Institute of Genetics and Biotechnology, Faculty of Biology, University of Warsaw, Pawińskiego 5a, 02-106, Warsaw, Poland
| | - Dariusz Koziorowski
- Department of Neurology, Faculty of Heath Science, Medical University of Warsaw, Kondratowicza 8, 03-242, Warsaw, Poland
| | - Kinga Duszyc
- Department of Medical Genetics, Institute of Mother and Child, Kasprzaka 17A, 01-211, Warsaw, Poland.,Institute of Genetics and Biotechnology, Faculty of Biology, University of Warsaw, Pawińskiego 5a, 02-106, Warsaw, Poland
| | - Paulina Górka-Skoczylas
- Institute of Genetics and Biotechnology, Faculty of Biology, University of Warsaw, Pawińskiego 5a, 02-106, Warsaw, Poland
| | - Anna Potulska-Chromik
- Department of Neurology, Medical University of Warsaw, Banacha 1, 02-097, Warsaw, Poland
| | - Jarosław Sławek
- Department of Neurological and Psychiatric Nursing, Medical University of Gdańsk, Dębinki 7, 80-952, Gdańsk, Poland
| | - Dorota Hoffman-Zacharska
- Department of Medical Genetics, Institute of Mother and Child, Kasprzaka 17A, 01-211, Warsaw, Poland. .,Institute of Genetics and Biotechnology, Faculty of Biology, University of Warsaw, Pawińskiego 5a, 02-106, Warsaw, Poland.
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21
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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: 52] [Impact Index Per Article: 5.8] [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.
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22
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Next-generation sequencing of duplication CNVs reveals that most are tandem and some create fusion genes at breakpoints. Am J Hum Genet 2015; 96:208-20. [PMID: 25640679 DOI: 10.1016/j.ajhg.2014.12.017] [Citation(s) in RCA: 112] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Accepted: 12/15/2014] [Indexed: 11/23/2022] Open
Abstract
Interpreting the genomic and phenotypic consequences of copy-number variation (CNV) is essential to understanding the etiology of genetic disorders. Whereas deletion CNVs lead obviously to haploinsufficiency, duplications might cause disease through triplosensitivity, gene disruption, or gene fusion at breakpoints. The mutational spectrum of duplications has been studied at certain loci, and in some cases these copy-number gains are complex chromosome rearrangements involving triplications and/or inversions. However, the organization of clinically relevant duplications throughout the genome has yet to be investigated on a large scale. Here we fine-mapped 184 germline duplications (14.7 kb-25.3 Mb; median 532 kb) ascertained from individuals referred for diagnostic cytogenetics testing. We performed next-generation sequencing (NGS) and whole-genome sequencing (WGS) to sequence 130 breakpoints from 112 subjects with 119 CNVs and found that most (83%) were tandem duplications in direct orientation. The remainder were triplications embedded within duplications (8.4%), adjacent duplications (4.2%), insertional translocations (2.5%), or other complex rearrangements (1.7%). Moreover, we predicted six in-frame fusion genes at sequenced duplication breakpoints; four gene fusions were formed by tandem duplications, one by two interconnected duplications, and one by duplication inserted at another locus. These unique fusion genes could be related to clinical phenotypes and warrant further study. Although most duplications are positioned head-to-tail adjacent to the original locus, those that are inverted, triplicated, or inserted can disrupt or fuse genes in a manner that might not be predicted by conventional copy-number assays. Therefore, interpreting the genetic consequences of duplication CNVs requires breakpoint-level analysis.
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23
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Rodriguez E, Sakowski L, Hobson GM, Armani MH, Kreiger PA, Zhu Y, Waldman SA, Shaffer TH. Plp1 gene duplication inhibits airway responsiveness and induces lung inflammation. Pulm Pharmacol Ther 2015; 30:22-31. [PMID: 25445931 PMCID: PMC6874309 DOI: 10.1016/j.pupt.2014.10.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Revised: 09/26/2014] [Accepted: 10/25/2014] [Indexed: 11/25/2022]
Abstract
Mice with Plp1 gene duplication model the most common form of Pelizaeus-Merzbacher disease (PMD), a CNS disease in which patients may suffer respiratory complications. We hypothesized that affected mice would lack airway responsiveness compared to wild-type and carrier mice during methacholine challenge. Wild-type (n = 10), carrier female (n = 6) and affected male (n = 8) mice were anesthetized-paralyzed, tracheostomized and ventilated. Respiratory mechanics were recorded at baseline and during escalating doses of nebulized methacholine followed by albuterol. Lung resistance (RL) was the primary endpoint. Lung tissues were assayed for inflammatory and histological differences. At baseline, phase angles were higher in carrier and affected mice than wild-type. Dose-response RL curves in affected and carrier mice indicated a lack of methacholine response. Albuterol reduced RL in wild-type and carrier, but not affected mice. Affected mice exhibited lower interleukin (IL)-6 tissue levels and alveolar inflammatory infiltrates. Affected and carrier mice, compared to wild-type, lacked airway reactivity during methacholine challenge, but only affected mice exhibited decreased lung tissue levels of IL-6 and inflammation.
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Affiliation(s)
- Elena Rodriguez
- Alfred I. duPont Hospital for Children, Nemours Lung Center, Wilmington, DE 19803, USA; Alfred I. duPont Hospital for Children, Nemours Biomedical Research, Wilmington, DE 19803, USA; Thomas Jefferson University, Division of Clinical Pharmacology, Dept. of Pharmacology and Experimental Therapeutics, Philadelphia, PA 19107, USA.
| | - Lauren Sakowski
- Center for Applied Clinical Genomics, Nemours Biomedical Research, Wilmington, DE 19803, USA; University of Delaware, Department of Biological Sciences, Newark, DE 19716, USA
| | - Grace M Hobson
- Alfred I. duPont Hospital for Children, Nemours Biomedical Research, Wilmington, DE 19803, USA; Center for Applied Clinical Genomics, Nemours Biomedical Research, Wilmington, DE 19803, USA; University of Delaware, Department of Biological Sciences, Newark, DE 19716, USA; Thomas Jefferson University, Department of Pediatrics, Philadelphia, PA 19107, USA
| | - Milena Hirata Armani
- Alfred I. duPont Hospital for Children, Nemours Lung Center, Wilmington, DE 19803, USA
| | - Portia A Kreiger
- Nemours Alfred I. duPont Hospital for Children, Department of Pathology, Wilmington, DE 19803, USA
| | - Yan Zhu
- Alfred I. duPont Hospital for Children, Nemours Lung Center, Wilmington, DE 19803, USA; Alfred I. duPont Hospital for Children, Nemours Biomedical Research, Wilmington, DE 19803, USA
| | - Scott A Waldman
- Thomas Jefferson University, Division of Clinical Pharmacology, Dept. of Pharmacology and Experimental Therapeutics, Philadelphia, PA 19107, USA
| | - Thomas H Shaffer
- Alfred I. duPont Hospital for Children, Nemours Lung Center, Wilmington, DE 19803, USA; Alfred I. duPont Hospital for Children, Nemours Biomedical Research, Wilmington, DE 19803, USA
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Appikatla S, Bessert D, Lee I, Hüttemann M, Mullins C, Somayajulu-Nitu M, Yao F, Skoff RP. Insertion of proteolipid protein into oligodendrocyte mitochondria regulates extracellular pH and adenosine triphosphate. Glia 2013; 62:356-73. [PMID: 24382809 DOI: 10.1002/glia.22591] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2013] [Revised: 10/04/2013] [Accepted: 10/07/2013] [Indexed: 11/08/2022]
Abstract
Proteolipid protein (PLP) and DM20, the most abundant myelin proteins, are coded by the human PLP1 and non-human Plp1 PLP gene. Mutations in the PLP1 gene cause Pelizaeus-Merzbacher disease (PMD) with duplications of the native PLP1 gene accounting for 70% of PLP1 mutations. Humans with PLP1 duplications and mice with extra Plp1 copies have extensive neuronal degeneration. The mechanism that causes neuronal degeneration is unknown. We show that native PLP traffics to mitochondria when the gene is duplicated in mice and in humans. This report is the first demonstration of a specific cellular defect in brains of PMD patients; it validates rodent models as ideal models to study PMD. Insertion of nuclear-encoded mitochondrial proteins requires specific import pathways; we show that specific cysteine motifs, part of the Mia40/Erv1 mitochondrial import pathway, are present in PLP and are required for its insertion into mitochondria. Insertion of native PLP into mitochondria of transfected cells acidifies media, partially due to increased lactate; it also increases adenosine triphosphate (ATP) in the media. The same abnormalities are found in the extracellular space of mouse brains with extra copies of Plp1. These physiological abnormalities are preventable by mutations in PLP cysteine motifs, a hallmark of the Mia40/Erv1 pathway. Increased extracellular ATP and acidosis lead to neuronal degeneration. Our findings may be the mechanism by which microglia are activated and proinflammatory molecules are upregulated in Plp1 transgenic mice (Tatar et al. (2010) ASN Neuro 2:art:e00043). Manipulation of this metabolic pathway may restore normal metabolism and provide therapy for PMD patients.
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Affiliation(s)
- Sunita Appikatla
- Department of Anatomy and Cell Biology, Wayne State University School of Medicine, Detroit, Michigan
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25
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Livnat A. Interaction-based evolution: how natural selection and nonrandom mutation work together. Biol Direct 2013; 8:24. [PMID: 24139515 PMCID: PMC4231362 DOI: 10.1186/1745-6150-8-24] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2013] [Accepted: 09/26/2013] [Indexed: 12/30/2022] Open
Abstract
BACKGROUND The modern evolutionary synthesis leaves unresolved some of the most fundamental, long-standing questions in evolutionary biology: What is the role of sex in evolution? How does complex adaptation evolve? How can selection operate effectively on genetic interactions? More recently, the molecular biology and genomics revolutions have raised a host of critical new questions, through empirical findings that the modern synthesis fails to explain: for example, the discovery of de novo genes; the immense constructive role of transposable elements in evolution; genetic variance and biochemical activity that go far beyond what traditional natural selection can maintain; perplexing cases of molecular parallelism; and more. PRESENTATION OF THE HYPOTHESIS Here I address these questions from a unified perspective, by means of a new mechanistic view of evolution that offers a novel connection between selection on the phenotype and genetic evolutionary change (while relying, like the traditional theory, on natural selection as the only source of feedback on the fit between an organism and its environment). I hypothesize that the mutation that is of relevance for the evolution of complex adaptation-while not Lamarckian, or "directed" to increase fitness-is not random, but is instead the outcome of a complex and continually evolving biological process that combines information from multiple loci into one. This allows selection on a fleeting combination of interacting alleles at different loci to have a hereditary effect according to the combination's fitness. TESTING AND IMPLICATIONS OF THE HYPOTHESIS This proposed mechanism addresses the problem of how beneficial genetic interactions can evolve under selection, and also offers an intuitive explanation for the role of sex in evolution, which focuses on sex as the generator of genetic combinations. Importantly, it also implies that genetic variation that has appeared neutral through the lens of traditional theory can actually experience selection on interactions and thus has a much greater adaptive potential than previously considered. Empirical evidence for the proposed mechanism from both molecular evolution and evolution at the organismal level is discussed, and multiple predictions are offered by which it may be tested. REVIEWERS This article was reviewed by Nigel Goldenfeld (nominated by Eugene V. Koonin), Jürgen Brosius and W. Ford Doolittle.
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Affiliation(s)
- Adi Livnat
- Department of Biological Sciences, Virginia Tech, Blacksburg, VA, 24061,
USA
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26
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Gait abnormalities and progressive myelin degeneration in a new murine model of Pelizaeus-Merzbacher disease with tandem genomic duplication. J Neurosci 2013; 33:11788-99. [PMID: 23864668 DOI: 10.1523/jneurosci.1336-13.2013] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Pelizaeus-Merzbacher disease (PMD) is a hypomyelinating leukodystrophy caused by mutations of the proteolipid protein 1 gene (PLP1), which is located on the X chromosome and encodes the most abundant protein of myelin in the central nervous sytem. Approximately 60% of PMD cases result from genomic duplications of a region of the X chromosome that includes the entire PLP1 gene. The duplications are typically in a head-to-tail arrangement, and they vary in size and gene content. Although rodent models with extra copies of Plp1 have been developed, none contains an actual genomic rearrangement that resembles those found in PMD patients. We used mutagenic insertion chromosome engineering resources to generate the Plp1dup mouse model by introducing an X chromosome duplication in the mouse genome that contains Plp1 and five neighboring genes that are also commonly duplicated in PMD patients. The Plp1dup mice display progressive gait abnormalities compared with wild-type littermates. The single duplication leads to increased transcript levels of Plp1 and four of the five other duplicated genes over wild-type levels in the brain beginning the second postnatal week. The Plp1dup mice also display altered transcript levels of other important myelin proteins leading to a progressive degeneration of myelin. Our results show that a single duplication of the Plp1 gene leads to a phenotype similar to the pattern seen in human PMD patients with duplications.
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27
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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.
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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
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28
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Martínez-Montero P, Muñoz-Calero M, Vallespín E, Campistol J, Martorell L, Ruiz-Falcó MJ, Santana A, Pons R, Dinopoulos A, Sierra C, Nevado J, Molano J. PLP1gene analysis in 88 patients with leukodystrophy. Clin Genet 2013; 84:566-71. [DOI: 10.1111/cge.12103] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2012] [Revised: 01/16/2013] [Accepted: 01/16/2013] [Indexed: 01/11/2023]
Affiliation(s)
| | - M Muñoz-Calero
- INGEMM, IdIPAZ, CIBERER; Hospital Universitario La Paz; Madrid Spain
| | - E Vallespín
- INGEMM, IdIPAZ, CIBERER; Hospital Universitario La Paz; Madrid Spain
| | | | - L Martorell
- Molecular Genetics Unit; Hospital Sant Joan de Deu; Barcelona Spain
| | - MJ Ruiz-Falcó
- Neurology Service; Hospital Infantil Universitario Niño Jesús; Madrid Spain
| | - A Santana
- Genetics Unit; C. U. Insular Materno Infantil; Las Palmas de Gran Canaria Spain
| | - R Pons
- Paediatric Neurology Service; University of Athens; "Attiko" University Hospital Athens; Athens Greece
| | - A Dinopoulos
- Paediatric Neurology Service; University of Athens; "Attiko" University Hospital Athens; Athens Greece
| | - C Sierra
- Paediatric Neurology Service; Complejo Hospitalario de Jaén; Jaén Spain
| | - J Nevado
- INGEMM, IdIPAZ, CIBERER; Hospital Universitario La Paz; Madrid Spain
| | - J Molano
- INGEMM, IdIPAZ, CIBERER; Hospital Universitario La Paz; Madrid Spain
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29
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Yamamoto T, Shimojima K. Pelizaeus-Merzbacher disease as a chromosomal disorder. Congenit Anom (Kyoto) 2013; 53:3-8. [PMID: 23480352 DOI: 10.1111/cga.12005] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/21/2012] [Accepted: 11/04/2012] [Indexed: 12/29/2022]
Abstract
Pelizaeus-Merzbacher disease (PMD) is a congenital hypomyelination disorder caused by alterations affecting the proteolipid protein 1 gene (PLP1) located on Xq22.2. Generally, patients with PLP1 missense mutations show the most severe form of PMD (connatal form); however, two-thirds of patients with PMD carry PLP1 duplications and present typical manifestations of the disorder, recognized as the classical form. Other rare PLP1 abnormalities have been also identified, including X-chromosome translocations, triplications, and a partial duplication, all involving PLP1. The genomic structure of the distal end of the PLP1 locus, characterized by repeated genomic segments, contributes to the chromosomal rearrangements around PLP1 and the manifestation of PMD. Thus, PMD is recognized as a chromosomal disorder.
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Affiliation(s)
- Toshiyuki Yamamoto
- Institute for Integrated Medical Sciences, Tokyo Women's Medical University, Tokyo, Japan.
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30
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Sun Z, Liu P, Jia X, Withers MA, Jin L, Lupski JR, Zhang F. Replicative mechanisms of CNV formation preferentially occur as intrachromosomal events: evidence from Potocki-Lupski duplication syndrome. Hum Mol Genet 2012; 22:749-56. [PMID: 23161748 DOI: 10.1093/hmg/dds482] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Copy number variations (CNVs) in the human genome contribute significantly to disease. De novo CNV mutations arise via genomic rearrangements, which can occur in 'trans', i.e. via interchromosomal events, or in 'cis', i.e. via intrachromosomal events. However, what molecular mechanisms occur between chromosomes versus between or within chromatids has not been systematically investigated. We hypothesized that distinct CNV mutational mechanisms, based on their intrinsic properties, may occur in a biased intrachromosomal versus interchromosomal manner. Here, we studied 62 genomic duplications observed in association with sporadic Potocki-Lupski syndrome (PTLS), in which multiple mutational mechanisms appear to be operative. Intriguingly, more interchromosomal than intrachromosomal events were identified in recurrent PTLS duplications mediated by non-allelic homologous recombination, whereas the reciprocal distribution was found for replicative mechanisms and non-homologous end-joining, likely reflecting the differences in spacial proximity of homologous chromosomes during different mutational processes.
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Affiliation(s)
- Zhe Sun
- State Key Laboratory of Genetic Engineering and MOE Key Laboratory of Contemporary Anthropology, School of Life Sciences, Fudan University, Shanghai 200433, China
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31
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Arlt MF, Rajendran S, Birkeland SR, Wilson TE, Glover TW. De novo CNV formation in mouse embryonic stem cells occurs in the absence of Xrcc4-dependent nonhomologous end joining. PLoS Genet 2012; 8:e1002981. [PMID: 23028374 PMCID: PMC3447954 DOI: 10.1371/journal.pgen.1002981] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2012] [Accepted: 08/01/2012] [Indexed: 11/20/2022] Open
Abstract
Spontaneous copy number variant (CNV) mutations are an important factor in genomic structural variation, genomic disorders, and cancer. A major class of CNVs, termed nonrecurrent CNVs, is thought to arise by nonhomologous DNA repair mechanisms due to the presence of short microhomologies, blunt ends, or short insertions at junctions of normal and de novo pathogenic CNVs, features recapitulated in experimental systems in which CNVs are induced by exogenous replication stress. To test whether the canonical nonhomologous end joining (NHEJ) pathway of double-strand break (DSB) repair is involved in the formation of this class of CNVs, chromosome integrity was monitored in NHEJ–deficient Xrcc4−/− mouse embryonic stem (ES) cells following treatment with low doses of aphidicolin, a DNA replicative polymerase inhibitor. Mouse ES cells exhibited replication stress-induced CNV formation in the same manner as human fibroblasts, including the existence of syntenic hotspot regions, such as in the Auts2 and Wwox loci. The frequency and location of spontaneous and aphidicolin-induced CNV formation were not altered by loss of Xrcc4, as would be expected if canonical NHEJ were the predominant pathway of CNV formation. Moreover, de novo CNV junctions displayed a typical pattern of microhomology and blunt end use that did not change in the absence of Xrcc4. A number of complex CNVs were detected in both wild-type and Xrcc4−/− cells, including an example of a catastrophic, chromothripsis event. These results establish that nonrecurrent CNVs can be, and frequently are, formed by mechanisms other than Xrcc4-dependent NHEJ. Copy number variants (CNVs) are a major factor in genetic variation and are a common and important class of mutation in genomic disorders, yet there is limited understanding of how many CNVs arise and the risk factors involved. One DNA damage response pathway implicated in CNV formation is nonhomologous end joining (NHEJ), which repairs broken DNA ends by Xrcc4-dependent direct ligation. We examined the effects of loss of Xrcc4 and NHEJ on CNV formation following replication stress in mouse cells. Cells lacking NHEJ displayed unaltered CNV frequencies, locations, and breakpoint structures compared to normal cells. These results establish that CNV mutations in a cell model system, and likely in vivo, arise by a mutagenic mechanism other than canonical NHEJ, a pattern similar to that reported for model translocation events. Potential roles of alternative end joining and template switching are discussed.
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Affiliation(s)
- Martin F. Arlt
- Department of Human Genetics, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Sountharia Rajendran
- Department of Human Genetics, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Shanda R. Birkeland
- Department of Pathology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Thomas E. Wilson
- Department of Human Genetics, University of Michigan, Ann Arbor, Michigan, United States of America
- Department of Pathology, University of Michigan, Ann Arbor, Michigan, United States of America
- * E-mail: (TEW); (TWG)
| | - Thomas W. Glover
- Department of Human Genetics, University of Michigan, Ann Arbor, Michigan, United States of America
- * E-mail: (TEW); (TWG)
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Anesi L, de Gemmis P, Galla D, Hladnik U. Two new large deletions of the AVPR2 gene causing nephrogenic diabetes insipidus and a review of previously published deletions. Nephrol Dial Transplant 2012; 27:3705-12. [PMID: 22879391 DOI: 10.1093/ndt/gfs359] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND In this paper, we report two new original deletions and present an extended review of the previously characterized AVPR2 gene deletions to better understand the underlying deletion mechanisms. METHODS The two novel deletions were defined using polymerase chain reaction mapping and junction fragment sequencing. Bioinformatic analysis was performed on both the previously mapped deletions and the novel ones through several web tools. RESULTS In our two patients with nephrogenic diabetes insipidus, we found a 23 755 bp deletion and a 9264 bp deletion both comprising the entire AVPR2 gene and part of the ARHGAP4 gene. Through bioinformatic studies, the smallest overlapping region as well as several motifs and repeats that are known to promote rearrangements were confirmed. CONCLUSIONS Through this study, it was determined that the deletion mechanisms in the AVPR2 region do not follow the rules of non-allelic homologous recombination. Two of the 13 deletions can be attributed to the fork stalling and template switching (FoSTeS) mechanism, whereas the remaining 11 deletions could be caused either by non-homologous end joining or by the FoSTeS mechanism. Although no recurrence was found, several groupings of deletion breakpoints were identified.
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Shimojima K, Inoue T, Imai Y, Arai Y, Komoike Y, Sugawara M, Fujita T, Ideguchi H, Yasumoto S, Kanno H, Hirose S, Yamamoto T. Reduced PLP1 expression in induced pluripotent stem cells derived from a Pelizaeus-Merzbacher disease patient with a partial PLP1 duplication. J Hum Genet 2012; 57:580-6. [PMID: 22695888 DOI: 10.1038/jhg.2012.71] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Pelizaeus-Merzbacher disease (PMD) is an X-linked recessive disorder characterized by dysmyelination of the central nervous system (CNS). We identified a rare partial duplication of the proteolipid protein 1 gene (PLP1) in a patient with PMD. To assess the underlying effect of this duplication, we examined PLP1 expression in induced pluripotent stem (iPS) cells generated from the patient's fibroblasts. Disease-specific iPS cells were generated from skin fibroblasts obtained from the indicated PMD patient and two other PMD patients having a 637-kb chromosomal duplication including entire PLP1 and a novel missense mutation (W212C) of PLP1, by transfections of OCT3/4, C-MYC, KLF4 and SOX2 using retro-virus vectors. PLP1 expressions in the generated iPS cells were examined by northern blot analysis. Although PLP1 expression was confirmed in iPS cells generated from two patients with the entire PLP1 duplication and the missense mutation of PLP1, iPS cells generated from the patient with the partial PLP1 duplication manifesting a milder form of PMD showed null expression. This indicated that the underlying effect of the partial PLP1 duplication identified in this study was different from other PLP1 alterations including a typical duplication and a missense mutation.
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Affiliation(s)
- Keiko Shimojima
- Precursory Research for Embryonic Science and Technology, Japan Science and Technology Agency, Kawaguchi, Japan
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Simmons AD, Carvalho CMB, Lupski JR. What have studies of genomic disorders taught us about our genome? Methods Mol Biol 2012; 838:1-27. [PMID: 22228005 DOI: 10.1007/978-1-61779-507-7_1] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The elucidation of genomic disorders began with molecular technologies that enabled detection of genomic changes which were (a) smaller than those resolved by traditional cytogenetics (less than 5 Mb) and (b) larger than what could be determined by conventional gel electrophoresis. Methods such as pulsed field gel electrophoresis (PFGE) and fluorescent in situ hybridization (FISH) could resolve such changes but were limited to locus-specific studies. The study of genomic disorders has rapidly advanced with the development of array-based techniques. These enabled examination of the entire human genome at a higher level of resolution, thus allowing elucidation of the basis of many new disorders, mechanisms that result in genomic changes that can result in copy number variation (CNV), and most importantly, a deeper understanding of the characteristics, features, and plasticity of our genome. In this chapter, we focus on the structural and architectural features of the genome, which can potentially result in genomic instability, delineate how mechanisms, such as NAHR, NHEJ, and FoSTeS/MMBIR lead to disease-causing rearrangements, and briefly describe the relationship between the leading methods presently used in studying genomic disorders. We end with a discussion on our new understanding about our genome including: the contribution of new mutation CNV to disease, the abundance of mosaicism, the extent of subtelomeric rearrangements, the frequency of de novo rearrangements associated with sporadic birth defects, the occurrence of balanced and unbalanced translocations, the increasing discovery of insertional translocations, the exploration of complex rearrangements and exonic CNVs. In the postgenomic era, our understanding of the genome has advanced very rapidly as the level of technical resolution has become higher. This leads to a greater understanding of the effects of rearrangements present both in healthy subjects and individuals with clinically relevant phenotypes.
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Mechanisms for recurrent and complex human genomic rearrangements. Curr Opin Genet Dev 2012; 22:211-20. [PMID: 22440479 DOI: 10.1016/j.gde.2012.02.012] [Citation(s) in RCA: 245] [Impact Index Per Article: 20.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2011] [Revised: 02/20/2012] [Accepted: 02/21/2012] [Indexed: 01/07/2023]
Abstract
During the last two decades, the importance of human genome copy number variation (CNV) in disease has become widely recognized. However, much is not understood about underlying mechanisms. We show how, although model organism research guides molecular understanding, important insights are gained from study of the wealth of information available in the clinic. We describe progress in explaining nonallelic homologous recombination (NAHR), a major cause of copy number change occurring when control of allelic recombination fails, highlight the growing importance of replicative mechanisms to explain complex events, and describe progress in understanding extreme chromosome reorganization (chromothripsis). Both nonhomologous end-joining and aberrant replication have significant roles in chromothripsis. As we study CNV, the processes underlying human genome evolution are revealed.
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Fusco F, Paciolla M, Napolitano F, Pescatore A, D'Addario I, Bal E, Lioi MB, Smahi A, Miano MG, Ursini MV. Genomic architecture at the Incontinentia Pigmenti locus favours de novo pathological alleles through different mechanisms. Hum Mol Genet 2011; 21:1260-71. [PMID: 22121116 DOI: 10.1093/hmg/ddr556] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
IKBKG/NEMO gene mutations cause an X-linked, dominant neuroectodermal disorder named Incontinentia Pigmenti (IP). Located at Xq28, IKBKG/NEMO has a unique genomic organization, as it is part of a segmental duplication or low copy repeat (LCR1-LCR2, >99% identical) containing the gene and its pseudogene copy (IKBKGP). In the opposite direction and outside LCR1, IKBKG/NEMO partially overlaps G6PD, whose mutations cause a common X-linked human enzymopathy. The two LCRs in the IKBKG/NEMO locus are able to recombine through non-allelic homologous recombination producing either a pathological recurrent exon 4-10 IKBKG/NEMO deletion (IKBKGdel) or benign small copy number variations. We here report that the local high frequency of micro/macro-homologies, tandem repeats and repeat/repetitive sequences make the IKBKG/NEMO locus susceptible to novel pathological IP alterations. Indeed, we describe the first two independent instances of inter-locus gene conversion, occurring between the two LCRs, that copies the IKBKGP pseudogene variants into the functional IKBKG/NEMO, causing the de novo occurrence of p.Glu390ArgfsX61 and the IKBKGdel mutations, respectively. Subsequently, by investigating a group of 20 molecularly unsolved IP subjects using a high-density quantitative polymerase chain reaction assay, we have identified seven unique de novo deletions varying from 4.8 to ∼115 kb in length. Each deletion removes partially or completely both IKBKG/NEMO and the overlapping G6PD, thereby uncovering the first deletions disrupting the G6PD gene which were found in patients with IP. Interestingly, the 4.8 kb deletion removes the conserved bidirectional promoterB, shared by the two overlapping IKBKG/NEMO and G6PD genes, leaving intact the alternative IKBKG/NEMO unidirectional promoterA. This promoter, although active in the keratinocytes of the basal dermal layer, is down-regulated during late differentiation. Genomic analysis at the breakpoint sites indicated that other mutational forces, such as non-homologous end joining, Alu-Alu-mediated recombination and replication-based events, might enhance the vulnerability of the IP locus to produce de novo pathological IP alleles.
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Affiliation(s)
- Francesca Fusco
- Institute of Genetics and Biophysics Adriano Buzzati-Traverso, IGB-CNR, Naples 80131, Italy
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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.
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Affiliation(s)
- C M B Carvalho
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
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38
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Grossi S, Regis S, Biancheri R, Mort M, Lualdi S, Bertini E, Uziel G, Boespflug-Tanguy O, Simonati A, Corsolini F, Demir E, Marchiani V, Percesepe A, Stanzial F, Rossi A, Vaurs-Barrière C, Cooper DN, Filocamo M. Molecular genetic analysis of the PLP1 gene in 38 families with PLP1-related disorders: identification and functional characterization of 11 novel PLP1 mutations. Orphanet J Rare Dis 2011; 6:40. [PMID: 21679407 PMCID: PMC3125326 DOI: 10.1186/1750-1172-6-40] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2011] [Accepted: 06/16/2011] [Indexed: 12/18/2022] Open
Abstract
Background The breadth of the clinical spectrum underlying Pelizaeus-Merzbacher disease and spastic paraplegia type 2 is due to the extensive allelic heterogeneity in the X-linked PLP1 gene encoding myelin proteolipid protein (PLP). PLP1 mutations range from gene duplications of variable size found in 60-70% of patients to intragenic lesions present in 15-20% of patients. Methods Forty-eight male patients from 38 unrelated families with a PLP1-related disorder were studied. All DNA samples were screened for PLP1 gene duplications using real-time PCR. PLP1 gene sequencing analysis was performed on patients negative for the duplication. The mutational status of all 14 potential carrier mothers of the familial PLP1 gene mutation was determined as well as 15/24 potential carrier mothers of the PLP1 duplication. Results and Conclusions PLP1 gene duplications were identified in 24 of the unrelated patients whereas a variety of intragenic PLP1 mutations were found in the remaining 14 patients. Of the 14 different intragenic lesions, 11 were novel; these included one nonsense and 7 missense mutations, a 657-bp deletion, a microdeletion and a microduplication. The functional significance of the novel PLP1 missense mutations, all occurring at evolutionarily conserved residues, was analysed by the MutPred tool whereas their potential effect on splicing was ascertained using the Skippy algorithm and a neural network. Although MutPred predicted that all 7 novel missense mutations would be likely to be deleterious, in silico analysis indicated that four of them (p.Leu146Val, p.Leu159Pro, p.Thr230Ile, p.Ala247Asp) might cause exon skipping by altering exonic splicing elements. These predictions were then investigated in vitro for both p.Leu146Val and p.Thr230Ile by means of RNA or minigene studies and were subsequently confirmed in the case of p.Leu146Val. Peripheral neuropathy was noted in four patients harbouring intragenic mutations that altered RNA processing, but was absent from all PLP1-duplication patients. Unprecedentedly, family studies revealed the de novo occurrence of the PLP1 duplication at a frequency of 20%.
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Affiliation(s)
- Serena Grossi
- SSD Lab, Diagnosi Pre-Postnatale Malattie Metaboliche, IRCCS G, Gaslini, Genova, Italy
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Karim SA, Barrie JA, McCulloch MC, Montague P, Edgar JM, Iden DL, Anderson TJ, Nave KA, Griffiths IR, McLaughlin M. PLP/DM20 expression and turnover in a transgenic mouse model of Pelizaeus-Merzbacher disease. Glia 2011; 58:1727-38. [PMID: 20629189 DOI: 10.1002/glia.21043] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The most common cause of Pelizaeus-Merzbacher (PMD) is due to duplication of the PLP1 gene but it is unclear how increased gene dosage affects PLP turnover and causes dysmyelination. We have studied the dynamics of PLP/DM20 in a transgenic mouse model of PMD with increased gene dosage of the proteolipid protein gene (Plp1). The turnover of PLP/DM20 were investigated using an ex-vivo brain slice system and cultured oligodendrocytes. Homozygous mice have reduced PLP translation, markedly enhanced PLP degradation, and markedly reduced incorporation of PLP into myelin. Proteasome inhibition (MG132) prevented the enhanced degradation. Numerous autophagic vesicles are present in homozygous transgenic mice that may influence protein dynamics. Surprisingly, promoting autophagy with rapamycin decreases the degradation of nascent PLP suggesting autophagic vacuoles serve as a cellular storage compartment. We suggest that there are multiple subcellular fates of PLP/DM20 when overexpressed: the vast majority being degraded by the proteasome, a proportion sequestered into autophagic vacuoles, probably fused with endolysosomes, and only a small proportion entering the myelin sheath, where its association with lipid rafts is perturbed. Transgenic oligodendrocytes have fewer membrane sheets and this phenotype is improved with siRNA-mediated knockdown of PLP expression that promotes the formation of MBP+ myelin-like sheets. This finding suggests that RNAi technology is in principle applicable to improve CNS myelination when compromised by PLP/DM20 overexpression.
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Affiliation(s)
- Saadia A Karim
- The Beatson Institute for Cancer Research, Garscube Estate, Switchback Road, Bearsden, Glasgow, G61 1BD, Scotland
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Oshima J, Lee JA, Breman AM, Fernandes PH, Babovic-Vuksanovic D, Ward PA, Wolfe LA, Eng CM, Del Gaudio D. LCR-initiated rearrangements at the IDS locus, completed with Alu-mediated recombination or non-homologous end joining. J Hum Genet 2011; 56:516-23. [PMID: 21593745 DOI: 10.1038/jhg.2011.51] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Mucopolysaccharidosis type II (MPS II) is caused by mutations in the IDS gene, which encodes the lysosomal enzyme iduronate-2-sulfatase. In ∼20% of MPS II patients the disorder is caused by gross IDS structural rearrangements. We identified two male cases harboring complex rearrangements involving the IDS gene and the nearby pseudogene, IDSP1, which has been annotated as a low-copy repeat (LCR). In both cases the rearrangement included a partial deletion of IDS and an inverted insertion of the neighboring region. In silico analyses revealed the presence of repetitive elements as well as LCRs at the junctions of rearrangements. Our models illustrate two alternative consequences of rearrangements initiated by non-allelic homologous recombination of LCRs: resolution by a second recombination event (that is, Alu-mediated recombination), or resolution by non-homologous end joining repair. These complex rearrangements have the potential to be recurrent and may be present among those MSP II cases with previously uncharacterized aberrations involving IDS.
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Affiliation(s)
- Junko Oshima
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
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Carvalho CMB, Zhang F, Lupski JR. Structural variation of the human genome: mechanisms, assays, and role in male infertility. Syst Biol Reprod Med 2011; 57:3-16. [PMID: 21210740 DOI: 10.3109/19396368.2010.527427] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Genomic disorders are defined as diseases caused by rearrangements of the genome incited by a genomic architecture that conveys instability. Y-chromosome related dysfunctions such as male infertility are frequently associated with gross DNA rearrangements resulting from its peculiar genomic architecture. The Y-chromosome has evolved into a highly specialized chromosome to perform male functions, mainly spermatogenesis. Direct and inverted repeats, some of them palindromes with highly identical nucleotide sequences that can form DNA cruciform structures, characterize the genomic structure of the Y-chromosome long arm. Some particular Y chromosome genomic deletions can cause spermatogenic failure likely because of removal of one or more transcriptional units with a potential role in spermatogenesis. We describe mechanisms underlying the formation of human genomic rearrangements on autosomes and review Y-chromosome deletions associated with male infertility.
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Affiliation(s)
- Claudia M B Carvalho
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030-3498, USA
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Sankaranarayanan K, Nikjoo H. Ionising radiation and genetic risks. XVI. A genome-based framework for risk estimation in the light of recent advances in genome research. Int J Radiat Biol 2010; 87:161-78. [DOI: 10.3109/09553002.2010.518214] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Schrider DR, Hahn MW. Lower linkage disequilibrium at CNVs is due to both recurrent mutation and transposing duplications. Mol Biol Evol 2010; 27:103-11. [PMID: 19745000 DOI: 10.1093/molbev/msp210] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Copy number variants (CNVs) within humans can have both adaptive and deleterious effects. Because of their phenotypic significance, researchers have attempted to find single nucleotide polymorphisms (SNPs) in high linkage disequilibrium (LD) with CNVs to use in genomewide association studies. However, studies have found that CNVs are less likely to be in strong LD with flanking markers. We hypothesized that this "taggability gap" can be explained by duplication events that place paralogous sequences far apart. In support of our hypothesis, we find that duplications are significantly less likely than deletions to have a "tag" SNP, even after controlling for CNV length, allele frequency, and availability of appropriate flanking SNPs. Using a novel likelihood method, we are able to show that many complex CNVs--those due to multiple duplication or deletion polymorphisms--are made up of two loci with little LD between them. Additionally, we find that many polymorphic duplications detected in a recent clone-based study are located far from their parental loci. We also examine two other common hypotheses for the taggability gap, and find that recurrent mutation of both deletions and duplications appears to have an effect on LD, but that lower SNP density around CNVs has no effect. Overall, our results suggest that a substantial fraction of CNVs caused by duplication cannot be tagged by markers flanking the parental locus because they have changed genomic location.
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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.
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Padiath QS, Fu YH. Autosomal dominant leukodystrophy caused by lamin B1 duplications a clinical and molecular case study of altered nuclear function and disease. Methods Cell Biol 2010; 98:337-57. [PMID: 20816241 DOI: 10.1016/s0091-679x(10)98014-x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Autosomal dominant leukodystrophy (ADLD) is an adult-onset demyelinating disorder that has recently shown to be caused by duplications of the nuclear lamina gene, lamin B1. This chapter attempts to collate and summarize the current knowledge about the disease and the clinical, pathological, and radiological presentations of the different ADLD families described till date. It also provides an overview of the molecular genetics underlying the disease and the mechanisms that may cause the duplication mutation event. ADLD is the first disease that has ever been linked to lamin B1 mutations and it expands the pathological role of the nuclear lamia to include disorders of the brain. The chapter also speculates on the different mechanisms that may link an important and ubiquitous structure like the nuclear lamina with the complex and cell-specific functions of myelin formation and maintenance. Understanding these mechanisms may not only prove helpful in understanding ADLD pathology but can also help in identifying new pathways that may be involved in myelin biology that can have implications for common demyelinating diseases like multiple sclerosis.
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Affiliation(s)
- Quasar Saleem Padiath
- Department of Neurology, University of California, San Francisco, San Francisco, California 94158, USA
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Cohn DM, Pagon RA, Hudgins L, Schwartz CE, Stevenson RE, Friez MJ. Partial ATRX gene duplication causes ATR-X syndrome. Am J Med Genet A 2009; 149A:2317-20. [PMID: 19764021 DOI: 10.1002/ajmg.a.33006] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Dianne M Cohn
- Greenwood Genetic Center, Greenwood, South Carolina 29646, USA
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Abstract
Variation in gene copy number is increasingly recognized as a common, heritable source of inter-individual differences in genomic sequence. The role of copy number variation is well established in the pathogenesis of rare genomic disorders. More recently, germline and somatic copy number variation have been shown to be important pathogenic factors in a range of common diseases, including infectious, autoimmune and neuropsychiatric diseases and cancer. In this review, we describe the range of methods available for measuring copy number variants (CNVs) in individuals and populations, including the limitations of presently available assays, and highlight some key examples of common diseases in which CNVs have been shown clearly to have a pathogenic role. Although there has been major progress in this field in the last 5 years, understanding the full contribution of CNVs to the genetic basis of common diseases will require further studies, with more accurate CNV assays and larger cohorts than have presently been completed.
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Affiliation(s)
- M Fanciulli
- Imperial College London, Hammersmith Hospital, London, W12 0NN, UK
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48
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Dosage-dependent severity of the phenotype in patients with mental retardation due to a recurrent copy-number gain at Xq28 mediated by an unusual recombination. Am J Hum Genet 2009; 85:809-22. [PMID: 20004760 DOI: 10.1016/j.ajhg.2009.10.019] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2009] [Revised: 10/19/2009] [Accepted: 10/22/2009] [Indexed: 12/22/2022] Open
Abstract
We report on the identification of a 0.3 Mb inherited recurrent but variable copy-number gain at Xq28 in affected males of four unrelated families with X-linked mental retardation (MR). All aberrations segregate with the disease in the families, and the carrier mothers show nonrandom X chromosome inactivation. Tiling Xq28-region-specific oligo array revealed that all aberrations start at the beginning of the low copy repeat LCR-K1, at position 153.20 Mb, and end just distal to LCR-L2, at 153.54 Mb. The copy-number gain always includes 18 annotated genes, of which RPL10, ATP6AP1 and GDI1 are highly expressed in brain. From these, GDI1 is the most likely candidate gene. Its copy number correlates with the severity of clinical features, because it is duplicated in one family with nonsyndromic moderate MR, is triplicated in males from two families with mild MR and additional features, and is present in five copies in a fourth family with a severe syndromic form of MR. Moreover, expression analysis revealed copy-number-dependent increased mRNA levels in affected patients compared to control individuals. Interestingly, analysis of the breakpoint regions suggests a recombination mechanism that involves two adjacent but different sets of low copy repeats. Taken together, our data strongly suggest that an increased expression of GDI1 results in impaired cognition in a dosage-dependent manner. Moreover, these data also imply that a copy-number gain of an individual gene present in the larger genomic aberration that leads to the severe MECP2 duplication syndrome can of itself result in a clinical phenotype as well.
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Hobson GM, Gibson CW, Aragon M, Yuan ZA, Davis-Williams A, Banser L, Kirkham J, Brook AH. A large X-chromosomal deletion is associated with microphthalmia with linear skin defects (MLS) and amelogenesis imperfecta (XAI). Am J Med Genet A 2009; 149A:1698-705. [PMID: 19610109 PMCID: PMC2760392 DOI: 10.1002/ajmg.a.32968] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
A female patient is described with clinical symptoms of both microphthalmia with linear skin defects (MLS or MIDAS) and dental enamel defects, having an appearance compatible with X-linked amelogenesis imperfecta (XAI). Genomic DNA was purified from the patient's blood and semiquantitative multiplex PCR revealed a deletion encompassing the amelogenin gene (AMELX). Because MLS is also localized to Xp22, genomic DNA was subjected to array comparative genomic hybridization, and a large heterozygous deletion was identified. Histopathology of one primary and one permanent molar tooth showed abnormalities in the dental enamel layer, and a third tooth had unusually high microhardness measurements, possibly due to its ultrastructural anomalies as seen by scanning electron microscopy. This is the first report of a patient with both of these rare conditions, and the first description of the phenotype resulting from a deletion encompassing the entire AMELX gene. More than 50 additional genes were monosomic in this patient.
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Affiliation(s)
- Grace M. Hobson
- Nemours Biomedical Research, Alfred I. duPont Hospital for Children, Wilmington, DE, USA
| | - Carolyn W. Gibson
- Department of Anatomy and Cell Biology, University of Pennsylvania School of Dental Medicine, Philadelphia, PA, USA
| | - Melissa Aragon
- Department of Anatomy and Cell Biology, University of Pennsylvania School of Dental Medicine, Philadelphia, PA, USA
| | - Zhi-an Yuan
- Department of Anatomy and Cell Biology, University of Pennsylvania School of Dental Medicine, Philadelphia, PA, USA
| | | | - Linda Banser
- Nemours Biomedical Research, Alfred I. duPont Hospital for Children, Wilmington, DE, USA
| | | | - Alan H. Brook
- International Collaborating Centre in Oro-facial Genetics and Development, University of Liverpool, Liverpool, UK
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50
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Kemppainen E, Fernández-Ayala DJM, Galbraith LCA, O'Dell KMC, Jacobs HT. Phenotypic suppression of the Drosophila mitochondrial disease-like mutant tko(25t) by duplication of the mutant gene in its natural chromosomal context. Mitochondrion 2009; 9:353-63. [PMID: 19616644 DOI: 10.1016/j.mito.2009.07.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2009] [Revised: 06/24/2009] [Accepted: 07/13/2009] [Indexed: 10/20/2022]
Abstract
A mutation in the Drosophila gene technical knockout (tko(25t)), encoding mitoribosomal protein S12, phenocopies human mitochondrial disease. We isolated three spontaneous X-dominant suppressors of tko(25t) (designated Weeble), exhibiting almost wild-type phenotype and containing overlapping segmental duplications including the mutant allele, plus a second mitoribosomal protein gene, mRpL14. Ectopic, expressed copies of tko(25t) and mRpL14 conferred no phenotypic suppression. When placed over a null allele of tko, Weeble retained the mutant phenotype, even in the presence of additional transgenic copies of tko(25t). Increased mutant gene dosage can thus compensate the mutant phenotype, but only when located in its normal chromosomal context.
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Affiliation(s)
- Esko Kemppainen
- Institute of Medical Technology and Tampere University Hospital, FI-33014 University of Tampere, Finland
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