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Darwish M, Hattori S, Nishizono H, Miyakawa T, Yachie N, Takao K. Comprehensive behavioral analyses of mice with a glycine receptor alpha 4 deficiency. Mol Brain 2023; 16:44. [PMID: 37217969 DOI: 10.1186/s13041-023-01033-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Accepted: 05/04/2023] [Indexed: 05/24/2023] Open
Abstract
Glycine receptors (GlyRs) are ligand-gated chloride channels comprising alpha (α1-4) and β subunits. The GlyR subunits play major roles in the mammalian central nervous system, ranging from regulating simple sensory information to modulating higher-order brain function. Unlike the other GlyR subunits, GlyR α4 receives relatively little attention because the human ortholog lacks a transmembrane domain and is thus considered a pseudogene. A recent genetic study reported that the GLRA4 pseudogene locus on the X chromosome is potentially involved in cognitive impairment, motor delay and craniofacial anomalies in humans. The physiologic roles of GlyR α4 in mammal behavior and its involvement in disease, however, are not known. Here we examined the temporal and spatial expression profile of GlyR α4 in the mouse brain and subjected Glra4 mutant mice to a comprehensive behavioral analysis to elucidate the role of GlyR α4 in behavior. The GlyR α4 subunit was mainly enriched in the hindbrain and midbrain, and had relatively lower expression in the thalamus, cerebellum, hypothalamus, and olfactory bulb. In addition, expression of the GlyR α4 subunit gradually increased during brain development. Glra4 mutant mice exhibited a decreased amplitude and delayed onset of the startle response compared with wild-type littermates, and increased social interaction in the home cage during the dark period. Glra4 mutants also had a low percentage of entries into open arms in the elevated plus-maze test. Although mice with GlyR α4 deficiency did not show motor and learning abnormalities reported to be associated in human genomics studies, they exhibited behavioral changes in startle response and social and anxiety-like behavior. Our data clarify the spatiotemporal expression pattern of the GlyR α4 subunit and suggest that glycinergic signaling modulates social, startle, and anxiety-like behaviors in mice.
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Affiliation(s)
- Mohamed Darwish
- Department of Behavioral Physiology, Graduate School of Innovative Life Science, University of Toyama, Toyama, Japan
- Department of Biochemistry, Faculty of Pharmacy, Cairo University, Cairo, Egypt
- Synthetic Biology Division, Research Center for Advanced Science and Technology, The University of Tokyo, Tokyo, Japan
| | - Satoko Hattori
- Division of Systems Medical Science, Center for Comprehensive Medical Science, Fujita Health University, Aichi, Toyoake, Japan
| | - Hirofumi Nishizono
- Medical Research Institute, Kanazawa Medical University, Kahoku, Ishikawa, Japan
| | - Tsuyoshi Miyakawa
- Division of Systems Medical Science, Center for Comprehensive Medical Science, Fujita Health University, Aichi, Toyoake, Japan
| | - Nozomu Yachie
- Synthetic Biology Division, Research Center for Advanced Science and Technology, The University of Tokyo, Tokyo, Japan
- School of Biomedical Engineering, The University of British Columbia, Vancouver, Canada
| | - Keizo Takao
- Department of Behavioral Physiology, Graduate School of Innovative Life Science, University of Toyama, Toyama, Japan.
- Department of Behavioral Physiology, Faculty of Medicine, University of Toyama, Toyama, Japan.
- Research Center for Idling Brain Science, University of Toyama, Toyama, Japan.
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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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Fonseca ACS, Bonaldi A, Costa SS, Freitas MR, Kok F, Vianna-Morgante AM. PLP1 duplication at the breakpoint regions of an apparently balanced t(X;22) translocation causes Pelizaeus-Merzbacher disease in a girl. Clin Genet 2012; 83:169-74. [PMID: 22320281 DOI: 10.1111/j.1399-0004.2012.01854.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
PLP1 (proteolipid protein1 gene) mutations cause Pelizaeus-Merzbacher disease (PMD), characterized by hypomyelination of the central nervous system, and affecting almost exclusively males. We report on a girl with classical PMD who carries an apparently balanced translocation t(X;22)(q22;q13). By applying array-based comparative genomic hybridization (a-CGH), we detected duplications at 22q13 and Xq22, encompassing 487-546 kb and 543-611 kb, respectively. The additional copies were mapped by fluorescent in situ hybridization to the breakpoint regions, on the derivative X chromosome (22q13 duplicated segment) and on the derivative 22 chromosome (Xq22 duplicated segment). One of the 14 duplicated X-chromosome genes was PLP1.The normal X chromosome was the inactive one in the majority of peripheral blood leukocytes, a pattern of inactivation that makes cells functionally balanced for the translocated segments. However, a copy of the PLP1 gene on the derivative chromosome 22, in addition to those on the X and der(X) chromosomes, resulted in two active copies of the gene, irrespective of the X-inactivation pattern, thus causing PMD. This t(X;22) is the first constitutional human apparently balanced translocation with duplications from both involved chromosomes detected at the breakpoint regions.
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Affiliation(s)
- A C S Fonseca
- Departamento de Genética e Biologia Evolutiva, Instituto de Biociências, Universidade de São Paulo, São Paulo, Brazil
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Abstract
Structural variation, whether it is caused by copy number variants or present in a balanced form, such as reciprocal translocations and inversions, can have a profound and dramatic effect on the expression of genes mapping within and close to the rearrangement, as well as affecting others genome wide. These effects can be caused by altering the copy number of one or more genes or regulatory elements (dosage effect) or from physical disruption of links between regulatory elements and their associated gene or genes, resulting in perturbation of expression. Similarly, large-scale structural variants can result in genome-wide expression changes by altering the positions that chromosomes occupy within the nucleus, potentially disrupting not only local cis interactions, but also trans interactions that occur throughout the genome. Structural variation is, therefore, a significant factor in the study of gene expression and is discussed here in more detail.
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Affiliation(s)
- Louise Harewood
- The Center for Integrative Genomics, University of Lausanne, Lausanne, Switzerland
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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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Abstract
Recent genetic epidemiology studies have been dominated by genome-wide association (GWA) studies using single nucleotide polymorphisms (SNPs). However, a form of structural genomic variation, termed copy number variation (CNV), is also widespread throughout the human genome, and can be highly polymorphic between individuals. Such variation has long been shown, through candidate gene studies using low-throughput molecular biology techniques, to have direct consequences on human health and variation. Many studies have now sought to extensively characterise this variation on a genome-wide scale and, increasingly, attempts are being made to identify associations between CNV and human disease. Although many of the study design issues that have been described for SNP GWA studies are also relevant for CNV GWA studies, CNV studies also present their own unique set of challenges and considerations. New microarray-based technologies are enabling more accurate mapping of CNVs, and CNV maps of the human genome are being regularly refined with increasing resolution. The study of CNV and its effects on human health and disease therefore present a dynamic and exciting challenge for researchers in the field of genetic epidemiology.
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Affiliation(s)
- Louise V Wain
- Department of Health Sciences, University of Leicester, Leicester, UK.
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Miller E, Widjaja E, Nilsson D, Yoon G, Banwell B, Blaser S. Magnetic resonance imaging of a unique mutation in a family with Pelizaeus-Merzbacher disease. Am J Med Genet A 2010; 152A:748-52. [DOI: 10.1002/ajmg.a.33305] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Kleinjan DJ, Coutinho P. Cis-ruption mechanisms: disruption of cis-regulatory control as a cause of human genetic disease. BRIEFINGS IN FUNCTIONAL GENOMICS AND PROTEOMICS 2009; 8:317-32. [PMID: 19596743 DOI: 10.1093/bfgp/elp022] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The spatiotemporally and quantitatively correct activity of a gene requires the presence of intact coding sequence as well as properly functioning regulatory control. One of the great challenges of the post-genome era is to gain a better understanding of the mechanisms of gene control. Proper gene regulation depends not only on the required transcription factors and associated complexes being present (in the correct dosage), but also on the integrity, chromatin conformation and nuclear positioning of the gene's chromosomal segment. Thus, when either the cis-trans regulatory system of a gene or the normal context of its chromatin structure are disrupted, gene expression may be adversely affected, potentially leading to disease. As transcriptional regulation is a highly complex process depending on many factors, there are many different mechanisms that can cause aberrant gene expression. Traditionally, the term 'position effect' was used to refer to situations where the level of expression of a gene is deleteriously affected by an alteration in its chromosomal environment, while maintaining an intact transcription unit. Over the past years, an ever increasing number of such disease-related position effect cases have come to light, and detailed studies have revealed insight into the variety of causes, which can be categorized into a number of different mechanistic groups. We suggest replacing the outdated term of 'position effect disease' with the new generic name of 'cis-ruption disorder' to describe genetic disease cases that are caused by disruption of the normal cis-regulatory architecture of the disease gene locus. Here, we review these various cis-ruption mechanisms and discuss how their studies have contributed to our understanding of long- range gene regulation.
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Affiliation(s)
- Dirk-Jan Kleinjan
- Institute of Genetics and Molecular Medicine, Western General Hospital, Edinburgh, EH4 2XU, UK.
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Henrichsen CN, Chaignat E, Reymond A. Copy number variants, diseases and gene expression. Hum Mol Genet 2009; 18:R1-8. [PMID: 19297395 DOI: 10.1093/hmg/ddp011] [Citation(s) in RCA: 292] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Copy number variation (CNV) has recently gained considerable interest as a source of genetic variation likely to play a role in phenotypic diversity and evolution. Much effort has been put into the identification and mapping of regions that vary in copy number among seemingly normal individuals in humans and a number of model organisms, using bioinformatics or hybridization-based methods. These have allowed uncovering associations between copy number changes and complex diseases in whole-genome association studies, as well as identify new genomic disorders. At the genome-wide scale, however, the functional impact of CNV remains poorly studied. Here we review the current catalogs of CNVs, their association with diseases and how they link genotype and phenotype. We describe initial evidence which revealed that genes in CNV regions are expressed at lower and more variable levels than genes mapping elsewhere, and also that CNV not only affects the expression of genes varying in copy number, but also have a global influence on the transcriptome. Further studies are warranted for complete cataloguing and fine mapping of CNVs, as well as to elucidate the different mechanisms by which they influence gene expression.
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Affiliation(s)
- Charlotte N Henrichsen
- The Center for Integrative Genomics, Genopode Building, University of Lausanne, Lausanne, Switzerland
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Henrichsen CN, Vinckenbosch N, Zöllner S, Chaignat E, Pradervand S, Schütz F, Ruedi M, Kaessmann H, Reymond A. Segmental copy number variation shapes tissue transcriptomes. Nat Genet 2009; 41:424-9. [PMID: 19270705 DOI: 10.1038/ng.345] [Citation(s) in RCA: 241] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2008] [Accepted: 01/05/2009] [Indexed: 01/08/2023]
Abstract
Copy number variation (CNV) is a key source of genetic diversity, but a comprehensive understanding of its phenotypic effect is only beginning to emerge. We have generated a CNV map in wild mice and classical inbred strains. Genome-wide expression data from six major organs show not only that expression of genes within CNVs tend to correlate with copy number changes, but also that CNVs influence the expression of genes in their vicinity, an effect that extends up to half a megabase. Genes within CNVs show lower expression and more specific spatial expression patterns than genes mapping elsewhere. Our analyses reveal differential constraint on copy number changes of genes expressed in different tissues. Dosage alterations of brain-expressed genes are less frequent than those of other genes and are buffered by tighter transcriptional regulation. Our study provides initial evidence that CNVs shape tissue transcriptomes on a global scale.
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Abstract
Pelizaeus-Merzbacher disease (PMD) is a recessive X-linked dysmyelinating disorder of the central nervous system (CNS). The most frequent cause of PMD is a genomic duplication of chromosome Xq22 including the region encoding the dosage-sensitive proteolipid protein 1 (PLP1) gene. The PLP1 duplications are heterogeneous in size, unlike duplications causing many other genomic disorders, and arise by a distinct molecular mechanism. Other causes of PMD include PLP1 deletions, triplications and point mutations. Mutations in the PLP1 gene can also give rise to spastic paraplegia type 2 (SPG2), an allelic form of the disease. Thus, there is a spectrum of CNS disorder from mild SPG2 to severe connatal PMD. PLP1 encodes a major protein in CNS myelin and is abundantly expressed in oligodendrocytes, the myelinating cells of the CNS. Significant advances in our understanding of PMD have been achieved by investigating mutant PLP1 in PMD patients, animal models and in vitro studies. How the different PLP1 mutations and dosage effects give rise to PMD is being revealed. Interestingly, the underlying causes of pathogenesis are distinct for each of the different genetic abnormalities. This article reviews the genetics of PMD and summarises the current knowledge of causative molecular and cellular mechanisms.
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Kleinjan DA, Lettice LA. Long-range gene control and genetic disease. ADVANCES IN GENETICS 2008; 61:339-88. [PMID: 18282513 DOI: 10.1016/s0065-2660(07)00013-2] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The past two decades have seen great progress in the elucidation of the genetic basis of human genetic disease. Many clinical phenotypes have been linked with mutations or deletions in specific causative genes. However, it is often less recognized that in addition to the integrity of the protein-coding sequences, human health critically also depends on the spatially, temporally, and quantitatively correct expression of those genes. Genetic disease can therefore equally be caused by disruption of the regulatory mechanisms that ensure proper gene expression. The term "position effect" is used in those situations where the expression level of a gene is deleteriously affected by an alteration in its chromosomal environment, while maintaining an intact transcription unit. Here, we review recent advances in our understanding of the possible mechanisms of a number of "position effect" disease cases and discuss the findings with respect to current models for genome organization and long-range control of gene expression.
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Affiliation(s)
- Dirk A Kleinjan
- MRC Human Genetics Unit, Western General Hospital, Edinburgh EH4 2XU, United Kingdom
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Reymond A, Henrichsen CN, Harewood L, Merla G. Side effects of genome structural changes. Curr Opin Genet Dev 2007; 17:381-6. [PMID: 17913489 DOI: 10.1016/j.gde.2007.08.009] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2007] [Accepted: 08/17/2007] [Indexed: 12/13/2022]
Abstract
The first extensive catalog of structural human variation was recently released. It showed that large stretches of genomic DNA that vary considerably in copy number were extremely abundant. Thus it is conceivable that they play a major role in functional variation. Consistently, genomic insertions and deletions were shown to contribute to phenotypic differences by modifying not only the expression levels of genes within the aneuploid segments but also of normal copy-number neighboring genes. In this report, we review the possible mechanisms behind this latter effect.
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Affiliation(s)
- Alexandre Reymond
- Center for Integrative Genomics, Genopode Building, University of Lausanne, CH-1015 Lausanne, Switzerland.
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Lee JA, Lupski JR. Genomic rearrangements and gene copy-number alterations as a cause of nervous system disorders. Neuron 2006; 52:103-21. [PMID: 17015230 DOI: 10.1016/j.neuron.2006.09.027] [Citation(s) in RCA: 199] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Genomic disorders are a group of human genetic diseases caused by genomic rearrangements resulting in copy-number variation (CNV) affecting a dosage-sensitive gene or genes critical for normal development or maintenance. These disorders represent a wide range of clinically distinct entities but include many diseases affecting nervous system function. Herein, we review selected neurodevelopmental, neurodegenerative, and psychiatric disorders either known or suggested to be caused by genomic rearrangement and CNV. Further, we emphasize the cause-and-effect relationship between gene CNV and complex disease traits. We also discuss the prevalence and heritability of CNV, the correlation between CNV and higher-order genome architecture, and the heritability of personality, behavioral, and psychiatric traits. We speculate that CNV could underlie a significant proportion of normal human variation including differences in cognitive, behavioral, and psychological features.
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Affiliation(s)
- Jennifer A Lee
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, 77030, USA
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Feuk L, Marshall CR, Wintle RF, Scherer SW. Structural variants: changing the landscape of chromosomes and design of disease studies. Hum Mol Genet 2006; 15 Spec No 1:R57-66. [PMID: 16651370 DOI: 10.1093/hmg/ddl057] [Citation(s) in RCA: 167] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The near completeness of human chromosome sequences is facilitating accurate characterization and assessment of all classes of genomic variation. Particularly, using the DNA reference sequence as a guide, genome scanning technologies, such as microarray-based comparative genomic hybridization (array CGH) and genome-wide single nucleotide polymorphism (SNP) platforms, have now enabled the detection of a previously unrecognized degree of larger-sized (non-SNP) variability in all genomes. This heterogeneity can include copy number variations (CNVs), inversions, insertions, deletions and other complex rearrangements, most of which are not detected by standard cytogenetics or DNA sequencing. Although these genomic alterations (collectively termed structural variants or polymorphisms) have been described previously, mainly through locus-specific studies, they are now known to be more global in occurrence. Moreover, as just one example, CNVs can contain entire genes and their number can correlate with the level of gene expression. It is also plausible that structural variants may commonly influence nearby genes through chromosomal positional or domain effects. Here, we discuss what is known of the prevalence of structural variants in the human genome and how they might influence phenotype, including the continuum of etiologic events underlying monogenic to complex diseases. Particularly, we highlight the newest studies and some classic examples of how structural variants might have adverse genetic consequences. We also discuss why analysis of structural variants should become a vital step in any genetic study going forward. All these progresses have set the stage for a golden era of combined microscopic and sub-microscopic (cytogenomic)-based research of chromosomes leading to a more complete understanding of the human genome.
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Affiliation(s)
- Lars Feuk
- The Centre for Applied Genomics and Program in Genetics and Genomic Biology, The Hospital for Sick Children, Department of Molecular and Medical Genetics, University of Toronto, Ontario, Canada.
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Lee JA, Madrid RE, Sperle K, Ritterson CM, Hobson GM, Garbern J, Lupski JR, Inoue K. Spastic paraplegia type 2 associated with axonal neuropathy and apparent PLP1 position effect. Ann Neurol 2006; 59:398-403. [PMID: 16374829 DOI: 10.1002/ana.20732] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECTIVE To report an association between spastic paraplegia type 2 with axonal peripheral neuropathy and apparent proteolipid protein gene (PLP1) silencing in a family. METHODS Pulsed-field gel electrophoresis, custom array comparative genomic hybridization, and semi-quantitative multiplex polymerase chain reaction analyses were used to examine the PLP1 genomic region. RESULTS Electrodiagnostic studies and a sural nerve biopsy showed features of a dystrophic axonal neuropathy. Molecular studies identified a small duplication downstream of PLP1. INTERPRETATION We propose the duplication to result in PLP1 gene silencing by virtue of a position effect. Our observations suggest that genomic rearrangements that do not include PLP1 coding sequences should be considered as yet another potential mutational mechanism underlying PLP1-related dysmyelinating disorders.
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Affiliation(s)
- Jennifer A Lee
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
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