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Zhang W, Tariq M, Roy B, Shen J, Khan A, Altaf Malik N, He S, Baig SM, Fang X, Zhang J. Whole exome sequencing identified a homozygous novel variant in DOP1A gene in the Pakistan family with neurodevelopmental disabilities: case report and literature review. Front Genet 2024; 15:1351710. [PMID: 38818041 PMCID: PMC11137318 DOI: 10.3389/fgene.2024.1351710] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2023] [Accepted: 04/11/2024] [Indexed: 06/01/2024] Open
Abstract
Background Hereditary neurodevelopmental disorders (NDDs) are prevalent in poorly prognostic pediatric diseases, but the pathogenesis of NDDs is still unclear. Irregular myelination could be one of the possible causes of NDDs. Case presentation Here, whole exome sequencing was carried out for a consanguineous Pakistani family with NDDs to identify disease-associated variants. The co-segregation of candidate variants in the family was validated using Sanger sequencing. The potential impact of the gene on NDDs has been supported by conservation analysis, protein prediction, and expression analysis. A novel homozygous variant DOP1A(NM_001385863.1):c.2561A>G was identified. It was concluded that the missense variant might affect the protein-protein binding sites of the critical MEC interaction region of DOP1A, and DOP1A-MON2 may cause stability deficits in Golgi-endosome protein traffic. Proteolipid protein (PLP) and myelin-associate glycoprotein (MAG) could be targets of the DOP1A-MON2 Golgi-endosome traffic complex, especially during the fetal stage and the early developmental stages. This further supports the perspective that disorganized myelinogenesis due to congenital DOP1A deficiency might cause neurodevelopmental disorders (NDDs). Conclusion Our case study revealed the potential pathway of myelinogenesis-relevant NDDs and identified DOP1A as a potential NDDs-relevant gene in humans.
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Affiliation(s)
- Wei Zhang
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
- BGI Genomics, Shenzhen, China
| | - Muhammad Tariq
- National Institute for Biotechnology and Genetic Engineering College, Pakistan Institute of Engineering and Applied Sciences (NIBGE-C PIEAS), Faisalabad, Pakistan
| | - Bhaskar Roy
- Hangzhou Institute of Medicine (HIM), Chinese Academy of Sciences, Hangzhou, Zhejiang, China
| | - Juan Shen
- Hangzhou Institute of Medicine (HIM), Chinese Academy of Sciences, Hangzhou, Zhejiang, China
- China National GeneBank, BGI-Shenzhen, Shenzhen, China
| | - Ayaz Khan
- National Institute for Biotechnology and Genetic Engineering College, Pakistan Institute of Engineering and Applied Sciences (NIBGE-C PIEAS), Faisalabad, Pakistan
| | - Naveed Altaf Malik
- National Institute for Biotechnology and Genetic Engineering College, Pakistan Institute of Engineering and Applied Sciences (NIBGE-C PIEAS), Faisalabad, Pakistan
| | - Sijie He
- Hebei Industrial Technology Research Institute of Genomics in Maternal and Child Health, Shijiazhuang, China
- Clin Lab, BGI Genomics, Shijiazhuang, China
| | - Shahid Mahmood Baig
- National Institute for Biotechnology and Genetic Engineering College, Pakistan Institute of Engineering and Applied Sciences (NIBGE-C PIEAS), Faisalabad, Pakistan
| | - Xiaodong Fang
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
- Hangzhou Institute of Medicine (HIM), Chinese Academy of Sciences, Hangzhou, Zhejiang, China
- China National GeneBank, BGI-Shenzhen, Shenzhen, China
| | - Jianguo Zhang
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
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Hasina Z, Wang N, Wang CC. Developmental Neuropathology and Neurodegeneration of Down Syndrome: Current Knowledge in Humans. Front Cell Dev Biol 2022; 10:877711. [PMID: 35676933 PMCID: PMC9168127 DOI: 10.3389/fcell.2022.877711] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Accepted: 04/18/2022] [Indexed: 12/25/2022] Open
Abstract
Individuals with Down syndrome (DS) suffer from developmental delay, intellectual disability, and an early-onset of neurodegeneration, Alzheimer’s-like disease, or precocious dementia due to an extra chromosome 21. Studying the changes in anatomical, cellular, and molecular levels involved may help to understand the pathogenesis and develop target treatments, not just medical, but also surgical, cell and gene therapy, etc., for individuals with DS. Here we aim to identify key neurodevelopmental manifestations, locate knowledge gaps, and try to build molecular networks to better understand the mechanisms and clinical importance. We summarize current information about the neuropathology and neurodegeneration of the brain from conception to adulthood of foetuses and individuals with DS at anatomical, cellular, and molecular levels in humans. Understanding the alterations and characteristics of developing Down syndrome will help target treatment to improve the clinical outcomes. Early targeted intervention/therapy for the manifestations associated with DS in either the prenatal or postnatal period may be useful to rescue the neuropathology and neurodegeneration in DS.
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Affiliation(s)
- Zinnat Hasina
- Department of Obstetrics & Gynaecology, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China
| | - Nicole Wang
- School of Veterinary Medicine, Glasgow University, Glasgow, United Kingdom
| | - Chi Chiu Wang
- Department of Obstetrics & Gynaecology, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China
- Li Ka Shing Institute of Health Sciences, School of Biomedical Sciences, Chinese University of Hong Kong -Sichuan University Joint Laboratory in Reproductive Medicine, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China
- *Correspondence: Chi Chiu Wang,
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Identifying Patients with Atrioventricular Septal Defect in Down Syndrome Populations by Using Self-Normalizing Neural Networks and Feature Selection. Genes (Basel) 2018; 9:genes9040208. [PMID: 29649131 PMCID: PMC5924550 DOI: 10.3390/genes9040208] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Revised: 03/28/2018] [Accepted: 04/03/2018] [Indexed: 02/06/2023] Open
Abstract
Atrioventricular septal defect (AVSD) is a clinically significant subtype of congenital heart disease (CHD) that severely influences the health of babies during birth and is associated with Down syndrome (DS). Thus, exploring the differences in functional genes in DS samples with and without AVSD is a critical way to investigate the complex association between AVSD and DS. In this study, we present a computational method to distinguish DS patients with AVSD from those without AVSD using the newly proposed self-normalizing neural network (SNN). First, each patient was encoded by using the copy number of probes on chromosome 21. The encoded features were ranked by the reliable Monte Carlo feature selection (MCFS) method to obtain a ranked feature list. Based on this feature list, we used a two-stage incremental feature selection to construct two series of feature subsets and applied SNNs to build classifiers to identify optimal features. Results show that 2737 optimal features were obtained, and the corresponding optimal SNN classifier constructed on optimal features yielded a Matthew’s correlation coefficient (MCC) value of 0.748. For comparison, random forest was also used to build classifiers and uncover optimal features. This method received an optimal MCC value of 0.582 when top 132 features were utilized. Finally, we analyzed some key features derived from the optimal features in SNNs found in literature support to further reveal their essential roles.
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Swaminathan S, Huentelman MJ, Corneveaux JJ, Myers AJ, Faber KM, Foroud T, Mayeux R, Shen L, Kim S, Turk M, Hardy J, Reiman EM, Saykin AJ. Analysis of copy number variation in Alzheimer's disease in a cohort of clinically characterized and neuropathologically verified individuals. PLoS One 2012; 7:e50640. [PMID: 23227193 PMCID: PMC3515604 DOI: 10.1371/journal.pone.0050640] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2012] [Accepted: 10/23/2012] [Indexed: 11/22/2022] Open
Abstract
Copy number variations (CNVs) are genomic regions that have added (duplications) or deleted (deletions) genetic material. They may overlap genes affecting their function and have been shown to be associated with disease. We previously investigated the role of CNVs in late-onset Alzheimer's disease (AD) and mild cognitive impairment using Alzheimer's Disease Neuroimaging Initiative (ADNI) and National Institute of Aging-Late Onset AD/National Cell Repository for AD (NIA-LOAD/NCRAD) Family Study participants, and identified a number of genes overlapped by CNV calls. To confirm the findings and identify other potential candidate regions, we analyzed array data from a unique cohort of 1617 Caucasian participants (1022 AD cases and 595 controls) who were clinically characterized and whose diagnosis was neuropathologically verified. All DNA samples were extracted from brain tissue. CNV calls were generated and subjected to quality control (QC). 728 cases and 438 controls who passed all QC measures were included in case/control association analyses including candidate gene and genome-wide approaches. Rates of deletions and duplications did not significantly differ between cases and controls. Case-control association identified a number of previously reported regions (CHRFAM7A, RELN and DOPEY2) as well as a new gene (HLA-DRA). Meta-analysis of CHRFAM7A indicated a significant association of the gene with AD and/or MCI risk (P = 0.006, odds ratio = 3.986 (95% confidence interval 1.490-10.667)). A novel APP gene duplication was observed in one case sample. Further investigation of the identified genes in independent and larger samples is warranted.
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Affiliation(s)
- Shanker Swaminathan
- Center for Neuroimaging, Department of Radiology and Imaging Sciences, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
| | - Matthew J. Huentelman
- Neurogenomics Division, The Translational Genomics Research Institute (TGen), Phoenix, Arizona, United States of America
- The Arizona Alzheimer's Consortium, Phoenix, Arizona, United States of America
| | - Jason J. Corneveaux
- Neurogenomics Division, The Translational Genomics Research Institute (TGen), Phoenix, Arizona, United States of America
- The Arizona Alzheimer's Consortium, Phoenix, Arizona, United States of America
| | - Amanda J. Myers
- Departments of Psychiatry and Behavioral Sciences, and Human Genetics and Genomics, University of Miami, Miller School of Medicine, Miami, Florida, United States of America
- Johnnie B. Byrd Sr. Alzheimer's Center and Research Institute, Tampa, Florida, United States of America
| | - Kelley M. Faber
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
| | - Tatiana Foroud
- Center for Neuroimaging, Department of Radiology and Imaging Sciences, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
- Center for Computational Biology and Bioinformatics, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
| | - Richard Mayeux
- The Gertrude H. Sergievsky Center, The Taub Institute for Research on Alzheimer's Disease and the Aging Brain, and the Department of Neurology, Columbia University College of Physicians and Surgeons, New York, New York, United States of America
| | - Li Shen
- Center for Neuroimaging, Department of Radiology and Imaging Sciences, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
- Center for Computational Biology and Bioinformatics, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
| | - Sungeun Kim
- Center for Neuroimaging, Department of Radiology and Imaging Sciences, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
- Center for Computational Biology and Bioinformatics, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
| | - Mari Turk
- Neurogenomics Division, The Translational Genomics Research Institute (TGen), Phoenix, Arizona, United States of America
- The Arizona Alzheimer's Consortium, Phoenix, Arizona, United States of America
| | - John Hardy
- Department of Molecular Neuroscience and Reta Lila Research Laboratories, University College London Institute of Neurology, London, United Kingdom
| | - Eric M. Reiman
- Neurogenomics Division, The Translational Genomics Research Institute (TGen), Phoenix, Arizona, United States of America
- The Arizona Alzheimer's Consortium, Phoenix, Arizona, United States of America
- Banner Alzheimer’s Institute, Phoenix, Arizona, United States of America
| | - Andrew J. Saykin
- Center for Neuroimaging, Department of Radiology and Imaging Sciences, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
- Center for Computational Biology and Bioinformatics, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
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Wiseman FK, Sheppard O, Linehan JM, Brandner S, Tybulewicz VLJ, Fisher EMC. Generation of a panel of antibodies against proteins encoded on human chromosome 21. J Negat Results Biomed 2010; 9:7. [PMID: 20727138 PMCID: PMC2936279 DOI: 10.1186/1477-5751-9-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2010] [Accepted: 08/20/2010] [Indexed: 11/17/2022] Open
Abstract
BACKGROUND Down syndrome (DS) is caused by trisomy of all or part of chromosome 21. To further understanding of DS we are working with a mouse model, the Tc1 mouse, which carries most of human chromosome 21 in addition to the normal mouse chromosome complement. This mouse is a model for human DS and recapitulates many of the features of the human syndrome such as specific heart defects, and cerebellar neuronal loss. The Tc1 mouse is mosaic for the human chromosome such that not all cells in the model carry it. Thus to help our investigations we aimed to develop a method to identify cells that carry human chromosome 21 in the Tc1 mouse. To this end, we have generated a panel of antibodies raised against proteins encoded by genes on human chromosome 21 that are known to be expressed in the adult brain of Tc1 mice RESULTS We attempted to generate human specific antibodies against proteins encoded by human chromosome 21. We selected proteins that are expressed in the adult brain of Tc1 mice and contain regions of moderate/low homology with the mouse ortholog. We produced antibodies to seven human chromosome 21 encoded proteins. Of these, we successfully generated three antibodies that preferentially recognise human compared with mouse SOD1 and RRP1 proteins on western blots. However, these antibodies did not specifically label cells which carry a freely segregating copy of Hsa21 in the brains of our Tc1 mouse model of DS. CONCLUSIONS Although we have successfully isolated new antibodies to SOD1 and RRP1 for use on western blots, in our hands these antibodies have not been successfully used for immunohistochemistry studies. These antibodies are freely available to other researchers. Our data high-light the technical difficulty of producing species-specific antibodies for both western blotting and immunohistochemistry.
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Affiliation(s)
- Frances K Wiseman
- Department of Neurodegenerative Disease, UCL Institute of Neurology, Queen Square, London WC1N 3BG, UK
| | - Olivia Sheppard
- Department of Neurodegenerative Disease, UCL Institute of Neurology, Queen Square, London WC1N 3BG, UK
| | - Jacqueline M Linehan
- Department of Neurodegenerative Disease, UCL Institute of Neurology, Queen Square, London WC1N 3BG, UK
| | - Sebastian Brandner
- Department of Neurodegenerative Disease, UCL Institute of Neurology, Queen Square, London WC1N 3BG, UK
| | - Victor LJ Tybulewicz
- MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, UK
| | - Elizabeth MC Fisher
- Department of Neurodegenerative Disease, UCL Institute of Neurology, Queen Square, London WC1N 3BG, UK
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Rachidi M, Lopes C. Molecular and cellular mechanisms elucidating neurocognitive basis of functional impairments associated with intellectual disability in Down syndrome. AMERICAN JOURNAL ON INTELLECTUAL AND DEVELOPMENTAL DISABILITIES 2010; 115:83-112. [PMID: 20441388 DOI: 10.1352/1944-7558-115.2.83] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2008] [Accepted: 11/05/2009] [Indexed: 05/29/2023]
Abstract
Down syndrome, the most common genetic cause of intellectual disability, is associated with brain disorders due to chromosome 21 gene overdosage. Molecular and cellular mechanisms involved in the neuromorphological alterations and cognitive impairments are reported herein in a global model. Recent advances in Down syndrome research have lead to the identification of altered molecular pathways involved in intellectual disability, such as Calcineurin/NFATs pathways, that are of crucial importance in understanding the molecular basis of intellectual disability pathogenesis in this syndrome. Potential treatments in mouse models of Down syndrome, including antagonists of NMDA or GABA(A) receptors, and microRNAs provide new avenues to develop treatments of intellectual disability. Nevertheless, understanding the links between molecular pathways and treatment strategies in human beings requires further research.
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Affiliation(s)
- Mohammed Rachidi
- University of Paris, Denis Diderot Laboratory of Genetic Dysregulation Models: Trisomy 21 and Hyperhomocysteinemia. Tour 54, Paris, France.
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Moldrich RX, Dauphinot L, Laffaire J, Vitalis T, Hérault Y, Beart PM, Rossier J, Vivien D, Gehrig C, Antonarakis SE, Lyle R, Potier MC. Proliferation deficits and gene expression dysregulation in Down's syndrome (Ts1Cje) neural progenitor cells cultured from neurospheres. J Neurosci Res 2009; 87:3143-52. [PMID: 19472221 DOI: 10.1002/jnr.22131] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Down's syndrome neurophenotypes are characterized by mental retardation and a decreased brain volume. To identify whether deficits in proliferation could be responsible for this phenotype, neural progenitor cells were isolated from the developing E14 neocortex of Down's syndrome partial trisomy Ts1Cje mice and euploid (WT) littermates and grown as neurospheres. Ts1Cje neural progenitors proliferated at a slower rate, because of a longer cell cycle, and a greater number of cells were positive for glial fibrillary acidic protein. An increase in cell death was also noted. Gene expression profiles of neural progenitor cells from Ts1Cje and WT showed that 54% of triploid genes had expression ratios (Ts1Cje/WT) significantly greater than the expected diploid gene ratio of 1.0. Some diploid genes associated with proliferation, differentiation, and glial function were dysregulated. Interestingly, proliferation and gene expression dysregulation detected in the Ts1Cje mice did not require overexpression of the chromosome 21 genes amyloid precursor protein (App) and soluble superoxide dismutase 1 (Sod1).
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Affiliation(s)
- Randal X Moldrich
- Laboratoire de Neurobiologie et Diversité Cellulaire, CNRS UMR7637, ESPCI, Paris, France
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Demirtas H. AgNOR status in Down's syndrome infants and a plausible phenotype formation hypothesis. Micron 2009; 40:511-8. [PMID: 19339189 DOI: 10.1016/j.micron.2009.02.014] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2008] [Revised: 02/25/2009] [Accepted: 02/25/2009] [Indexed: 10/21/2022]
Abstract
Down's syndrome (DS) or trisomy 21 is the most frequent genetic birth defect associated with mental retardation. Although DS has been known for more than a 100 years and its chromosomal basis recognized for half a century (1959), the underlying patho-mechanisms for the phenotype formation remain elusive and cannot be fully explained by simple gene dosage effect. The general consensus is that the extra chromosome 21 genes perturb the global metabolism of the body cells. Our experiments show that the most prominent metabolic perturbation occurs during ribosome biogenesis in the cells of DS babies/infants. In humans, ribosomal RNA (rRNA) gene families or nucleolar organizer regions (NORs) are localized at the secondary constriction (on the satellite stalks) of five pairs of acrocentric chromosomes (13, 14, 15, 21 and 22) and their activities are evaluated specifically either in metaphase or interphase through a procedure known as AgNOR or silver staining. Our successive AgNOR studies, supported by RNA and nuclear protein measurement, show that cells from DS infants produce more ribosomes than expected, accounting for the extra set of active rRNA gene family (1/6-1/11) situated on the extra chromosome 21. Thus, the presence of an extra chromosome 21 stimulates a global increase in ribosome biogenesis in cooperation with other NOR-bearing chromosomes, causing unnecessary rRNA and ribosomal proteins synthesis compared to controls. Following the description of NORs, AgNOR, AgNOR-proteins, AgNOR measurement and our experimental results, we propose that the extra RNA and protein synthesis can cause a fundamental handicap to DS infants, contributing to the formation of DS phenotypes, due to the wasted energy in producing unnecessary macromolecules, including energy (GTP)-dependent transport of the excessive ribosomes from the nucleus to the cytoplasm.
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Affiliation(s)
- Halil Demirtas
- Erciyes University, Medical Faculty, Medical Biology Department 38039 Kayseri, Turkey.
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Yilmaz SI, Demirtas H. AgNOR increase in buccal epithelial cells of trisomy 21 infants. Micron 2008; 39:1262-5. [DOI: 10.1016/j.micron.2008.03.014] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2008] [Revised: 03/27/2008] [Accepted: 03/28/2008] [Indexed: 12/11/2022]
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Mental retardation and associated neurological dysfunctions in Down syndrome: a consequence of dysregulation in critical chromosome 21 genes and associated molecular pathways. Eur J Paediatr Neurol 2008; 12:168-82. [PMID: 17933568 DOI: 10.1016/j.ejpn.2007.08.010] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/01/2007] [Revised: 08/19/2007] [Accepted: 08/21/2007] [Indexed: 12/11/2022]
Abstract
Down syndrome (DS), affecting 1/700 live births, is the major genetic cause of mental retardation (MR), a cognitive disorder with hard impact on public health. DS brain is characterized by a reduced cerebellar volume and number of granular cells, defective cortical lamination and reduced cortical neurons, malformed dendritic trees and spines, and abnormal synapses. These neurological alterations, also found in trisomic mouse models, result from gene-dosage effects of Human Chromosome 21 (HC21) on the expression of critical developmental genes. HC21 sequencing, mouse ortholog gene identification and DS mouse model generation lead to determine HC21 gene functions and the effects of protein-dosage alterations in neurodevelopmental and metabolic pathways in DS individuals. Trisomic brain transcriptome of DS patients and trisomic mouse models identified some molecular changes determined by gene-overdosage and associated dysregulation of some disomic gene expression in DS brains. These transcriptional variations cause developmental alterations in neural patterning and signal transduction pathways that may lead to defective neuronal circuits responsible for the pathogenesis of MR in DS. Recently, the first altered molecular pathway responsible of some DS phenotypes, including neurological and cognitive disorders has been identified. In this pathway, two critical HC21 genes (DYRK1A and DSCR1) act synergistically to control the phosphorylation levels of NFATc and NFATc-regulated gene expression. Interestingly, the NFATc mice show neurological dysfunctions similar to those seen in DS patients and trisomic mouse models. Treatment of DS mouse model Ts65Dn with GABA(A) antagonists allowed post-drug rescue of cognitive defects, indicating a hopeful direction in clinical therapies for MR in children with DS.
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Greene AK, Kim S, Rogers GF, Fishman SJ, Olsen BR, Mulliken JB. Risk of vascular anomalies with Down syndrome. Pediatrics 2008; 121:e135-40. [PMID: 18166531 DOI: 10.1542/peds.2007-1316] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
OBJECTIVE Patients with Down syndrome have a reduced risk of developing solid tumors. This protective effect has been attributed to increased gene dosage from an additional copy of chromosome 21, and elevated expression of endostatin has been implicated. We hypothesized that vascular anomalies, including infantile hemangioma, an angiogenesis-dependent vascular tumor, and vascular malformations might be similarly inhibited in patients with Down syndrome. PATIENTS AND METHODS The Children's Hospital Boston Vascular Anomalies Center database was searched for patients with Down syndrome between 1999 and 2007. In addition, the records of patients with Down syndrome treated at Children's Hospital Boston and the National Birth Defects Center between 1985 and 2007 were reviewed to find concurrent vascular anomalies. Two-sided exact binomial tests were used to evaluate whether patients with vascular anomalies are at reduced risk for Down syndrome or if patients with Down syndrome are at less risk for vascular anomalies compared with the general population. Ninety-five-percent confidence intervals were calculated on the basis of the risk of Down syndrome (1 in 800) and vascular anomalies (1 in 22) in the general population. RESULTS Two of the 7354 patients evaluated in our vascular anomalies unit had Down syndrome. Both patients had a lymphatic malformation: one in the orbit and the other in the lower extremity. Six of the 633 patients with Down syndrome had a vascular anomaly (infantile hemangioma [n = 4] or lymphatic malformation [n = 2]). The risk of concurrent Down syndrome and vascular anomalies was different from the corresponding risk in the general population. CONCLUSIONS Patients with Down syndrome have a reduced risk of vascular anomalies compared with the general population. Elevated expression of antiangiogenic proteins may protect these patients from developing vascular anomalies, as well as solid tumors.
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Affiliation(s)
- Arin K Greene
- Vascular Anomalies Center and Department of Plastic Surgery, Children's Hospital Boston, Harvard Medical School, Boston, Massachusetts 02115, USA.
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Rachidi M, Lopes C. Mental retardation in Down syndrome: From gene dosage imbalance to molecular and cellular mechanisms. Neurosci Res 2007; 59:349-69. [PMID: 17897742 DOI: 10.1016/j.neures.2007.08.007] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2007] [Revised: 08/02/2007] [Accepted: 08/10/2007] [Indexed: 11/25/2022]
Abstract
Down syndrome (DS), the most frequent genetic disorder leading to mental retardation (MR), is caused by three copies of human chromosome 21 (HC21). Trisomic and transgenic mouse models for DS allow genetic dissection of DS neurological and cognitive disorders in view to identify genes responsible for these phenotypes. The effects of the gene dosage imbalance on DS phenotypes are explained by two hypotheses: the "gene dosage effect" hypothesis claims that a DS critical region, containing a subset of dosage-sensitive genes, determines DS phenotypes, and the "amplified developmental instability" hypothesis holds that HC21 trisomy determines general alteration in developmental homeostasis. Transcriptome and expression studies showed different up- or down-expression levels of genes located on HC21 and the other disomic chromosomes. HC21 genes, characterized by their overexpression in brain regions affected in DS patients and by their contribution to neurological and cognitive defects when overexpressed in mouse models, are proposed herein as good candidates for MR. In this article, we propose a new molecular and cellular mechanism explaining MR pathogenesis in DS. In this model, gene dosage imbalance effects on transcriptional variations are described considering the nature of gene products and their functional relationships. These transcriptional variations may affect different aspects of neuronal differentiation and metabolism and finally, determine the brain neuropathologies and mental retardation in DS.
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New cerebellar phenotypes in YAC transgenic mouse in vivo library of human Down syndrome critical region-1. Biochem Biophys Res Commun 2007; 364:488-94. [PMID: 17963726 DOI: 10.1016/j.bbrc.2007.10.035] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2007] [Accepted: 10/06/2007] [Indexed: 11/22/2022]
Abstract
Down syndrome (DS) is the most frequent genetic cause of mental retardation (MR) associated with neurological alterations. To allow a genetic dissection of DS phenotype, we studied eight transgenic mouse lines carrying YACs containing human DNA fragments covering DS critical region (DCR-1), as an in vivo library. Herein, we found an increased brain size in the 152F7-mice containing DYRK1A gene. We also identified a new cerebellar alteration in two independent lines carrying 230E8-YAC. These mice showed significant elongation of the cerebellar antero-posterior axis (p<0.001), determined by increased length of rostral folia of the vermis (lobule II-V, p<0.0001; lobule VI, p<0.001). In addition, we identified a major neurological defect in culmen and declivus lobules in the 230E8-mice. We analyzed P30, P12, and P9 stages and detected high significant increased lengths of anterior lobules (II-VI) of 230E8-mice at P30 and P12 (lobule II-V, p<0.0001; lobule VI, p<0.05), but not at P9, indicating that this new phenotype appears between P9 and P12. Interestingly, 230E8-mice also present increased cortical cell density and mild learning defects. 230E8-YAC contains seven genes, some of which could be potentially responsible for this phenotype. Between them, we proposed DOPEY2 as potential candidate gene for these cerebellar alterations considering its high expression in the brain and that its homologous genes in yeast, Caenorhabditis elegans and Drosophila are involved in morphogenesis, suggesting a conserved role of DOPEY2 as a patterning gene.
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