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Kuru K, Niranjan M, Tunca Y, Osvank E, Azim T. Biomedical visual data analysis to build an intelligent diagnostic decision support system in medical genetics. Artif Intell Med 2014; 62:105-18. [PMID: 25262492 DOI: 10.1016/j.artmed.2014.08.003] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2013] [Revised: 08/15/2014] [Accepted: 08/16/2014] [Indexed: 11/30/2022]
Abstract
BACKGROUND In general, medical geneticists aim to pre-diagnose underlying syndromes based on facial features before performing cytological or molecular analyses where a genotype-phenotype interrelation is possible. However, determining correct genotype-phenotype interrelationships among many syndromes is tedious and labor-intensive, especially for extremely rare syndromes. Thus, a computer-aided system for pre-diagnosis can facilitate effective and efficient decision support, particularly when few similar cases are available, or in remote rural districts where diagnostic knowledge of syndromes is not readily available. METHODS The proposed methodology, visual diagnostic decision support system (visual diagnostic DSS), employs machine learning (ML) algorithms and digital image processing techniques in a hybrid approach for automated diagnosis in medical genetics. This approach uses facial features in reference images of disorders to identify visual genotype-phenotype interrelationships. Our statistical method describes facial image data as principal component features and diagnoses syndromes using these features. RESULTS The proposed system was trained using a real dataset of previously published face images of subjects with syndromes, which provided accurate diagnostic information. The method was tested using a leave-one-out cross-validation scheme with 15 different syndromes, each of comprised 5-9 cases, i.e., 92 cases in total. An accuracy rate of 83% was achieved using this automated diagnosis technique, which was statistically significant (p<0.01). Furthermore, the sensitivity and specificity values were 0.857 and 0.870, respectively. CONCLUSION Our results show that the accurate classification of syndromes is feasible using ML techniques. Thus, a large number of syndromes with characteristic facial anomaly patterns could be diagnosed with similar diagnostic DSSs to that described in the present study, i.e., visual diagnostic DSS, thereby demonstrating the benefits of using hybrid image processing and ML-based computer-aided diagnostics for identifying facial phenotypes.
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Affiliation(s)
- Kaya Kuru
- Department of Communication, Electronics, and Information Systems, Gülhane Military Medical Academy, Etlik, Ankara 06010, Turkey.
| | - Mahesan Niranjan
- School of Electronics and Computer Science, University of Southampton, Southampton SO17 1BF, UK
| | - Yusuf Tunca
- Department of Medical Genetics, Gülhane Military Medical Academy, Etlik, Ankara 06010, Turkey
| | - Erhan Osvank
- Institute of Informatics, Middle East Technical University, Balgat, Ankara 06531, Turkey
| | - Tayyaba Azim
- School of Electronics and Computer Science, University of Southampton, Southampton SO17 1BF, UK
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152
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Weissman J, Naidu S, Bjornsson HT. Abnormalities of the DNA methylation mark and its machinery: an emerging cause of neurologic dysfunction. Semin Neurol 2014; 34:249-57. [PMID: 25192503 PMCID: PMC4512289 DOI: 10.1055/s-0034-1386763] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Recently, Mendelian disorders of the DNA methylation machinery have been described which demonstrate the complex roles of epigenetics in neurodevelopment and disease. For example, defects of DNMT1, the maintenance methyltransferase, lead to adult-onset progressive neurologic disorders, whereas defects of the de novo methyltransferases DNMT3A and DNMT3B lead to nonprogressive neurodevelopmental conditions. Furthermore, patients with DNMT3A deficiency demonstrate overgrowth, a feature common to disorders of histone machinery and imprinting disorders, highlighting the interconnectedness of the many epigenetic layers. Disorders of the DNA methylation machinery include both the aforementioned "writers" and also the "readers" of the methyl mark, such as MeCP2, the cause of Rett syndrome. Any dosage disruption, either haploinsufficiency or overexpression of DNA methylation machinery leads to widespread gene expression changes in trans, disrupting expression of a subset of target genes that contribute to individual disease phenotypes. In contrast, classical imprinting disorders such as Angelman syndrome have been thought generally to cause epigenetic dysregulation in cis. However, the recent description of multilocus methylation disorders challenges this generalization. Here, in addition to summarizing recent developments in identifying the pathogenesis of these diseases, we highlight clinical considerations and some unexpected therapeutic opportunities, such as topoisomerase inhibitors for classical imprinting disorders.
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Affiliation(s)
- Jacqueline Weissman
- Kennedy Krieger Institute, Baltimore, Maryland
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland
- Department of Pediatrics, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Sakkubai Naidu
- Kennedy Krieger Institute, Baltimore, Maryland
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland
- Department of Pediatrics, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Hans T. Bjornsson
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland
- Department of Pediatrics, Johns Hopkins University School of Medicine, Baltimore, Maryland
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153
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Jang J, Quan Z, Yum YJ, Song HS, Paek S, Kang HC. Induced pluripotent stem cells for modeling of pediatric neurological disorders. Biotechnol J 2014; 9:871-81. [PMID: 24838856 DOI: 10.1002/biot.201400010] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2014] [Revised: 03/29/2014] [Accepted: 05/15/2014] [Indexed: 12/14/2022]
Abstract
The pathophysiological mechanisms underlying childhood neurological disorders have remained obscure due to a lack of suitable disease models reflecting human pathogenesis. Using induced pluripotent stem cell (iPSC) technology, various neurological disorders can now be extensively modeled. Specifically, iPSC technology has aided the study and treatment of early-onset pediatric neurodegenerative diseases such as Rett syndrome, Down syndrome, Angelman syndrome. Prader-Willi syndrome, Friedreich's ataxia, spinal muscular atrophy (SMA), fragile X syndrome, X-linked adrenoleukodystrophy (ALD), and SCN1A gene-related epilepsies. In this paper, we provide an overview of various gene delivery systems for generating iPSCs, the current state of modeling early-onset neurological disorders and the ultimate application of these in vitro models in cell therapy through the correction of disease-specific mutations.
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Affiliation(s)
- Jiho Jang
- Department of Physiology, Yonsei University College of Medicine, Seoul, Korea
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154
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Abstract
"Angelman syndrome" (AS) is a neurodevelopmental disorder whose main features are intellectual disability, lack of speech, seizures, and a characteristic behavioral profile. The behavioral features of AS include a happy demeanor, easily provoked laughter, short attention span, hypermotoric behavior, mouthing of objects, sleep disturbance, and an affinity for water. Microcephaly and subtle dysmorphic features, as well as ataxia and other movement disturbances, are additional features seen in most affected individuals. AS is due to deficient expression of the ubiquitin protein ligase E3A (UBE3A) gene, which displays paternal imprinting. There are four molecular classes of AS, and some genotype-phenotype correlations have emerged. Much remains to be understood regarding how insufficiency of E6-AP, the protein product of UBE3A, results in the observed neurodevelopmental deficits. Studies of mouse models of AS have implicated UBE3A in experience-dependent synaptic remodeling.
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Affiliation(s)
- Lynne M Bird
- Department of Pediatrics, University of California, Division of Genetics, Rady Children’s Hospital, San Diego, California, USA
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155
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Godavarthi SK, Sharma A, Jana NR. Reversal of reduced parvalbumin neurons in hippocampus and amygdala of Angelman syndrome model mice by chronic treatment of fluoxetine. J Neurochem 2014; 130:444-54. [DOI: 10.1111/jnc.12726] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2014] [Revised: 03/20/2014] [Accepted: 03/25/2014] [Indexed: 01/23/2023]
Affiliation(s)
- Swetha K. Godavarthi
- Cellular and Molecular Neuroscience Laboratory; National Brain Research Centre; Manesar Gurgaon India
| | - Ankit Sharma
- Cellular and Molecular Neuroscience Laboratory; National Brain Research Centre; Manesar Gurgaon India
| | - Nihar Ranjan Jana
- Cellular and Molecular Neuroscience Laboratory; National Brain Research Centre; Manesar Gurgaon India
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156
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Coppus AMW. People with intellectual disability: what do we know about adulthood and life expectancy? ACTA ACUST UNITED AC 2014; 18:6-16. [PMID: 23949824 DOI: 10.1002/ddrr.1123] [Citation(s) in RCA: 209] [Impact Index Per Article: 20.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2012] [Revised: 12/03/2012] [Accepted: 12/20/2012] [Indexed: 12/13/2022]
Abstract
Increases in the life expectancy of people with Intellectual Disability have followed similar trends to those found in the general population. With the exception of people with severe and multiple disabilities or Down syndrome, the life expectancy of this group now closely approximates with that of the general population. Middle and old age, which until 30 years ago were not recognized in this population, are now important parts of the life course of these individuals. Older adults with Intellectual Disabilities form a small, but significant and growing proportion of older people in the community. How these persons grow older and how symptoms and complications of the underlying cause of the Intellectual Disability will influence their life expectancy is of the utmost importance.
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Affiliation(s)
- A M W Coppus
- Dichterbij, Center for the Intellectually Disabled, Medical Center, Gennep, The Netherlands.
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157
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Hodge JC, Mitchell E, Pillalamarri V, Toler TL, Bartel F, Kearney HM, Zou YS, Tan WH, Hanscom C, Kirmani S, Hanson RR, Skinner SA, Rogers C, Everman DB, Boyd E, Mullegama SV, Keelean-Fuller D, Powell CM, Elsea SH, Morton CC, Gusella JF, DuPont B, Chaubey A, Lin AE, Talkowski ME, Talkowski ME. Disruption of MBD5 contributes to a spectrum of psychopathology and neurodevelopmental abnormalities. Mol Psychiatry 2014; 19:368-79. [PMID: 23587880 PMCID: PMC4756476 DOI: 10.1038/mp.2013.42] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/22/2012] [Revised: 02/11/2013] [Accepted: 03/06/2013] [Indexed: 01/11/2023]
Abstract
Microdeletions of chromosomal region 2q23.1 that disrupt MBD5 (methyl-CpG-binding domain protein 5) contribute to a spectrum of neurodevelopmental phenotypes; however, the impact of this locus on human psychopathology has not been fully explored. To characterize the structural variation landscape of MBD5 disruptions and the associated human psychopathology, 22 individuals with genomic disruption of MBD5 (translocation, point mutation and deletion) were identified through whole-genome sequencing or cytogenomic microarray at 11 molecular diagnostic centers. The genomic impact ranged from a single base pair to 5.4 Mb. Parents were available for 11 cases, all of which confirmed that the rearrangement arose de novo. Phenotypes were largely indistinguishable between patients with full-segment 2q23.1 deletions and those with intragenic MBD5 rearrangements, including alterations confined entirely to the 5'-untranslated region, confirming the critical impact of non-coding sequence at this locus. We identified heterogeneous, multisystem pathogenic effects of MBD5 disruption and characterized the associated spectrum of psychopathology, including the novel finding of anxiety and bipolar disorder in multiple patients. Importantly, one of the unique features of the oldest known patient was behavioral regression. Analyses also revealed phenotypes that distinguish MBD5 disruptions from seven well-established syndromes with significant diagnostic overlap. This study demonstrates that haploinsufficiency of MBD5 causes diverse phenotypes, yields insight into the spectrum of resulting neurodevelopmental and behavioral psychopathology and provides clinical context for interpretation of MBD5 structural variations. Empirical evidence also indicates that disruption of non-coding MBD5 regulatory regions is sufficient for clinical manifestation, highlighting the limitations of exon-focused assessments. These results suggest an ongoing perturbation of neurological function throughout the lifespan, including risks for neurobehavioral regression.
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Affiliation(s)
- Jennelle C. Hodge
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, USA,Department of Medical Genetics, Mayo Clinic, Rochester, 55905, USA
| | - Elyse Mitchell
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, USA
| | - Vamsee Pillalamarri
- Center for Human Genetic Research, Massachusetts General Hospital, Boston, MA, USA
| | - Tomi L. Toler
- Medical Genetics, MassGeneral Hospital for Children, Boston, MA, USA
| | | | | | - Ying S. Zou
- Clinical Cytogenetics Laboratory, Pathology Associates Medical Laboratories, Spokane, WA, USA
| | - Wen-Hann Tan
- Division of Genetics, Boston Children’s Hospital, Boston, MA, USA,Harvard Medical School, Boston, MA, USA
| | - Carrie Hanscom
- Center for Human Genetic Research, Massachusetts General Hospital, Boston, MA, USA
| | - Salman Kirmani
- Department of Medical Genetics, Mayo Clinic, Rochester, 55905, USA
| | - Rae R. Hanson
- Child Neurology, Department of Neurosciences, Mayo Clinic Health System, Eau Claire, WI, USA
| | | | | | | | - Ellen Boyd
- Fullerton Genetic Center, Mission Health, Asheville, NC, USA
| | - Sureni V. Mullegama
- Department of Human and Molecular Genetics, Virginia Commonwealth University School of Medicine, Richmond, VA, USA
| | - Debra Keelean-Fuller
- Department of Pediatrics and Genetics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Cynthia M. Powell
- Department of Pediatrics and Genetics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Sarah H. Elsea
- Department of Human and Molecular Genetics, Virginia Commonwealth University School of Medicine, Richmond, VA, USA,Department of Pediatrics, Virginia Commonwealth University School of Medicine, Richmond, VA, USA
| | - Cynthia C. Morton
- Harvard Medical School, Boston, MA, USA,Departments of Obstetrics, Gynecology and Reproductive Biology and of Pathology, Brigham and Women’s Hospital, Boston, MA, USA,Program in Medical and Population Genetics, Broad Institute of Harvard and M.I.T., Cambridge, MA, USA
| | - James F. Gusella
- Center for Human Genetic Research, Massachusetts General Hospital, Boston, MA, USA,Program in Medical and Population Genetics, Broad Institute of Harvard and M.I.T., Cambridge, MA, USA,Departments of Genetics and Neurology, Harvard Medical School, Cambridge, MA, USA
| | | | | | - Angela E. Lin
- Center for Human Genetic Research, Massachusetts General Hospital, Boston, MA, USA,Medical Genetics, MassGeneral Hospital for Children, Boston, MA, USA
| | - Michael E. Talkowski
- Center for Human Genetic Research, Massachusetts General Hospital, Boston, MA, USA,Program in Medical and Population Genetics, Broad Institute of Harvard and M.I.T., Cambridge, MA, USA,Departments of Genetics and Neurology, Harvard Medical School, Cambridge, MA, USA
| | - M E Talkowski
- 1] Center for Human Genetic Research, Massachusetts General Hospital, Boston, MA, USA [2] Program in Medical and Population Genetics, Broad Institute of Harvard and MIT, Cambridge, MA, USA [3] Departments of Genetics and Neurology, Harvard Medical School, Cambridge, MA, USA
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158
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Congenital Arthrogryposis: An Extension of the 15q11.2 BP1-BP2 Microdeletion Syndrome? Case Rep Genet 2014; 2014:127258. [PMID: 24778887 PMCID: PMC3978403 DOI: 10.1155/2014/127258] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2013] [Accepted: 12/10/2013] [Indexed: 11/18/2022] Open
Abstract
The proximal 15q11–q13 region contains 5 breakpoints (BP1–BP5). The BP1-BP2 region spans approximately 500 kb and contains four evolutionarily conserved genes. The genes in this region are known to play a role in central nervous system development and/or function. Microdeletions within the 15q11.2 BP1-BP2 region have been reported in patients with neurological dysfunction, developmental delays, behavioral problems, and dysmorphic features. We report two unrelated subjects with the 15q11.2 BP1-BP2 microdeletion and presenting with congenital arthrogryposis, a feature which has not been previously reported as part of this newly recognized microdeletion syndrome. While arthrogryposis seen in these two subjects may be coincidental, we propose that congenital arthrogryposis may result from neurological dysfunction and involvement of the microdeletion of the 15q11.2 BP1-BP2 region, further expanding the phenotype of this microdeletion syndrome. We encourage others to report patients with this chromosome microdeletion and neurological findings to further characterize the clinical phenotype.
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159
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Chang CW, Hsu HK, Kao CC, Huang JY, Kuo PL. Prenatal diagnosis of Prader-Willi syndrome and Angelman syndrome for fetuses with suspicious deletion of chromosomal region 15q11-q13. Int J Gynaecol Obstet 2014; 125:18-21. [DOI: 10.1016/j.ijgo.2013.09.028] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2013] [Revised: 09/11/2013] [Accepted: 12/22/2013] [Indexed: 02/07/2023]
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160
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Meng L, Person RE, Huang W, Zhu PJ, Costa-Mattioli M, Beaudet AL. Truncation of Ube3a-ATS unsilences paternal Ube3a and ameliorates behavioral defects in the Angelman syndrome mouse model. PLoS Genet 2013; 9:e1004039. [PMID: 24385930 PMCID: PMC3873245 DOI: 10.1371/journal.pgen.1004039] [Citation(s) in RCA: 109] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2013] [Accepted: 11/04/2013] [Indexed: 11/18/2022] Open
Abstract
Angelman syndrome (AS) is a severe neurodevelopmental disorder caused by maternal deficiency of the imprinted gene UBE3A. Individuals with AS suffer from intellectual disability, speech impairment, and motor dysfunction. Currently there is no cure for the disease. Here, we evaluated the phenotypic effect of activating the silenced paternal allele of Ube3a by depleting its antisense RNA Ube3a-ATS in mice. Premature termination of Ube3a-ATS by poly(A) cassette insertion activates expression of Ube3a from the paternal chromosome, and ameliorates many disease-related symptoms in the AS mouse model, including motor coordination defects, cognitive deficit, and impaired long-term potentiation. Studies on the imprinting mechanism of Ube3a revealed a pattern of biallelic transcription initiation with suppressed elongation of paternal Ube3a, implicating transcriptional collision between sense and antisense polymerases. These studies demonstrate the feasibility and utility of unsilencing the paternal copy of Ube3a via targeting Ube3a-ATS as a treatment for Angelman syndrome. Angelman syndrome (AS) is a devastating neurodevelopmental disorder diagnosed in young children, currently with no effective treatments. It is characterized by absence of speech, ataxia, intellectual disability, epilepsy, and a characteristic behavior of frequent laughter and smiling. The disease is caused by loss of the maternal allele of UBE3A, which is preferentially silenced on the paternal chromosome and expressed on the maternal chromosome in neurons due to genomic imprinting. It has been long proposed that by activating the originally silenced paternal allele of UBE3A, the disease may be cured. Here in our research, we demonstrated the feasibility of activating paternal Ube3a in mice by terminating the transcription of its antisense RNA Ube3a-ATS genetically. In the AS mouse model who additionally receives the terminated Ube3a-ATS allele from the paternal side, we observed restoration of Ube3a expression, amelioration of behavioral defects and reversal of the impaired long-term potentiation. We further studied the imprinting mechanisms of Ube3a and proposed a novel transcriptional collision model. These results provide solid in vivo evidence for a key regulatory role of Ube3a-ATS in the disease and open up an exciting possibility of a gene-specific treatment for Angelman syndrome.
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Affiliation(s)
- Linyan Meng
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Richard Erwin Person
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Wei Huang
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas, United States of America
| | - Ping Jun Zhu
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas, United States of America
| | - Mauro Costa-Mattioli
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas, United States of America
| | - Arthur L. Beaudet
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
- * E-mail:
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161
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Au PB, Argiropoulos B, Parboosingh JS, Micheil Innes A. Refinement of the critical region of 1q41q42 microdeletion syndrome identifiesFBXO28as a candidate causative gene for intellectual disability and seizures. Am J Med Genet A 2013; 164A:441-8. [DOI: 10.1002/ajmg.a.36320] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2013] [Accepted: 10/06/2013] [Indexed: 12/21/2022]
Affiliation(s)
- P.Y. Billie Au
- Department of Medical Genetics; University of Calgary; Calgary Alberta Canada
| | - Bob Argiropoulos
- Department of Medical Genetics; University of Calgary; Calgary Alberta Canada
- Alberta Children's Hospital Research Institute for Child and Maternal Health; University of Calgary; Calgary Alberta Canada
| | - Jillian S. Parboosingh
- Department of Medical Genetics; University of Calgary; Calgary Alberta Canada
- Alberta Children's Hospital Research Institute for Child and Maternal Health; University of Calgary; Calgary Alberta Canada
| | - A. Micheil Innes
- Department of Medical Genetics; University of Calgary; Calgary Alberta Canada
- Alberta Children's Hospital Research Institute for Child and Maternal Health; University of Calgary; Calgary Alberta Canada
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162
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Sánchez J, Fernández R, Madruga M, Bernabeu-Wittel J, Antiñolo G, Borrego S. Somatic and germ-line mosaicism of deletion 15q11.2-q13 in a mother of dyzigotic twins with Angelman syndrome. Am J Med Genet A 2013; 164A:370-6. [DOI: 10.1002/ajmg.a.36281] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2012] [Accepted: 09/12/2013] [Indexed: 12/15/2022]
Affiliation(s)
- Javier Sánchez
- Department of Genetics; Reproduction and Fetal Medicine; Institute of Biomedicine of Seville (IBIS); University Hospital Virgen del Rocío; CSIC; University of Seville; Seville Spain
| | - Raquel Fernández
- Department of Genetics; Reproduction and Fetal Medicine; Institute of Biomedicine of Seville (IBIS); University Hospital Virgen del Rocío; CSIC; University of Seville; Seville Spain
- Centre of Biomedical Network Research on Rare Diseases (CIBERER); Seville Spain
| | - Marcos Madruga
- Department of Pediatrics; University Hospital Virgen del Rocío; Seville Spain
| | | | - Guillermo Antiñolo
- Department of Genetics; Reproduction and Fetal Medicine; Institute of Biomedicine of Seville (IBIS); University Hospital Virgen del Rocío; CSIC; University of Seville; Seville Spain
- Centre of Biomedical Network Research on Rare Diseases (CIBERER); Seville Spain
| | - Salud Borrego
- Department of Genetics; Reproduction and Fetal Medicine; Institute of Biomedicine of Seville (IBIS); University Hospital Virgen del Rocío; CSIC; University of Seville; Seville Spain
- Centre of Biomedical Network Research on Rare Diseases (CIBERER); Seville Spain
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163
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Caldeira MV, Salazar IL, Curcio M, Canzoniero LMT, Duarte CB. Role of the ubiquitin-proteasome system in brain ischemia: friend or foe? Prog Neurobiol 2013; 112:50-69. [PMID: 24157661 DOI: 10.1016/j.pneurobio.2013.10.003] [Citation(s) in RCA: 94] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2013] [Revised: 10/08/2013] [Accepted: 10/15/2013] [Indexed: 11/26/2022]
Abstract
The ubiquitin-proteasome system (UPS) is a catalytic machinery that targets numerous cellular proteins for degradation, thus being essential to control a wide range of basic cellular processes and cell survival. Degradation of intracellular proteins via the UPS is a tightly regulated process initiated by tagging a target protein with a specific ubiquitin chain. Neurons are particularly vulnerable to any change in protein composition, and therefore the UPS is a key regulator of neuronal physiology. Alterations in UPS activity may induce pathological responses, ultimately leading to neuronal cell death. Brain ischemia triggers a complex series of biochemical and molecular mechanisms, such as an inflammatory response, an exacerbated production of misfolded and oxidized proteins, due to oxidative stress, and the breakdown of cellular integrity mainly mediated by excitotoxic glutamatergic signaling. Brain ischemia also damages protein degradation pathways which, together with the overproduction of damaged proteins and consequent upregulation of ubiquitin-conjugated proteins, contribute to the accumulation of ubiquitin-containing proteinaceous deposits. Despite recent advances, the factors leading to deposition of such aggregates after cerebral ischemic injury remain poorly understood. This review discusses the current knowledge on the role of the UPS in brain function and the molecular mechanisms contributing to UPS dysfunction in brain ischemia with consequent accumulation of ubiquitin-containing proteins. Chemical inhibitors of the proteasome and small molecule inhibitors of deubiquitinating enzymes, which promote the degradation of proteins by the proteasome, were both shown to provide neuroprotection in brain ischemia, and this apparent contradiction is also discussed in this review.
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Affiliation(s)
- Margarida V Caldeira
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, Largo Marquês de Pombal, 3004-517 Coimbra, Portugal; Department of Life Sciences, University of Coimbra, 3004-517 Coimbra, Portugal
| | - Ivan L Salazar
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, Largo Marquês de Pombal, 3004-517 Coimbra, Portugal; Doctoral Programme in Experimental Biology and Biomedicine, Center for Neuroscience and Cell Biology, University of Coimbra, Portugal; Institute for Interdisciplinary Research, University of Coimbra (IIIUC), Portugal
| | - Michele Curcio
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, Largo Marquês de Pombal, 3004-517 Coimbra, Portugal; Department of Science and Technology, University of Sannio, Benevento, Italy
| | | | - Carlos B Duarte
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, Largo Marquês de Pombal, 3004-517 Coimbra, Portugal; Department of Life Sciences, University of Coimbra, 3004-517 Coimbra, Portugal.
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164
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Gilboa T, Gross-Tsur V. Epilepsy in Prader-Willi syndrome: experience of a national referral centre. Dev Med Child Neurol 2013; 55:857-61. [PMID: 23750756 DOI: 10.1111/dmcn.12182] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 03/22/2013] [Indexed: 12/11/2022]
Abstract
AIM The aim of the study was to characterize epilepsy, febrile seizures, electrographic features, and brain abnormalities in a large, national cohort of individuals with Prader-Willi syndrome (PWS). METHOD This was an observational cohort study. Clinic charts of 126 individuals (63 males, 63 females) with genetically confirmed PWS (due to a deletion in 72 cases, to uniparental disomy [UPD] in 51 cases, and to an imprinting centre defect in two cases), aged from 1 month to 48 years (mean age 13y), were reviewed and 119 interviews conducted. Information regarding seizures, medication, imaging studies, and family history of seizures was collected. Ninety-five individuals (aged 1mo-48y) underwent electroencephalography (EEG). RESULTS Five individuals had epilepsy (4.0%), three of whom had major cerebral findings on imaging, and eight others had febrile seizures (6.4%). Of the three genetic abnormalities, deletion was associated with seizures. Focal epileptiform abnormalities were found in 12 out of 94 individuals, and five out of these 12 had a frank electrographic seizure pattern. Epileptogenic EEG abnormalities were associated with young age. INTERPRETATION The risk of epilepsy and febrile seizures in PWS is significantly lower than in Angelman syndrome and is associated with brain abnormalities. Electrographic seizures and focal epileptiform activity were present in 5% of individuals and were associated with young age. The underpinnings of epileptiform abnormalities in PWS and how they differ from those of the Angelman syndrome should be studied further.
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Affiliation(s)
- Tal Gilboa
- Child Neurology Unit, Shaare Zedek Medical Center, Jerusalem, Israel.
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165
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Al-Maawali A, Machado J, Fang P, Dupuis L, Faghfoury H, Mendoza-Londono R. Angelman syndrome due to a termination codon mutation of the UBE3A gene. J Child Neurol 2013; 28:392-5. [PMID: 22566713 DOI: 10.1177/0883073812443591] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Angelman syndrome is a neurodevelopmental disorder characterized by global developmental delay, mental retardation, seizures, microcephaly, and severe speech delay. It may be caused by deletion of chromosome region 15q11.2 of the maternally inherited chromosome, mutations in the UBE3A gene, uniparental disomy, or imprinting defects. Most patients with this diagnosis have a severe phenotype, and a few have a mild form of the disease. We report a patient with a novel mutation in the UBE3A gene that consists of a deletion of the termination codon (c.2556-*+6del GTAAAACAAA) and results in an elongated protein E3 ubiquitin-protein ligase. Our patient has a mild phenotype compared with other patients in general and specifically to patients with UBE3A mutations. He has mild developmental delay, moderate speech delay, and no seizures. Recognition of this genotype-phenotype correlation will allow better genetic counseling to other patients with similar stop codon mutations.
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Affiliation(s)
- Almundher Al-Maawali
- Division of Clinical and Metabolic Genetics, Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
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166
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Faulkner MA, Singh SP. Neurogenetic disorders and treatment of associated seizures. Pharmacotherapy 2013; 33:330-43. [PMID: 23400943 DOI: 10.1002/phar.1201] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Seizures are a frequent complication associated with several neurogenetic disorders. Antiepileptic medications remain the mainstay of treatment in these patients. We summarized the available data associated with various antiepileptic therapies used to treat patients with neurogenetic disorders who experienced recurrent seizures. A MEDLINE search was conducted to identify articles and abstracts describing the use of antiepileptic therapy for the treatment of various neurogenetic syndromes. Of all the neurogenetic syndromes, only autism spectrum disorders, Angelman syndrome, Rett syndrome, Dravet syndrome, and tuberous sclerosis complex were identified as having sufficient published information to evaluate therapy. Some efficacy trends were identified, including frequent successes with valproic acid with clonazepam for epilepsy with Angelman syndrome; valproic acid, stiripentol, and clobazam (triple combination therapy) for epilepsy with Dravet syndrome; and vigabatrin for infantile spasms associated with tuberous sclerosis complex. Due to a paucity of information regarding the mechanisms by which seizures are generated in the various disorders, approach to seizure control is primarily based on clinical experience and a limited amount of study data exploring patient outcomes. Although exposure of the developing brain to antiepileptic medications is of some concern, the control of epileptic activity is an important undertaking in these individuals, as the severity of eventual developmental delay often appears to correlate with the severity of seizures. As such, early aggressive therapy is warranted.
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Affiliation(s)
- Michele A Faulkner
- Departments of Pharmacy Practice and Neurology, Creighton University School of Pharmacy and Health Professions, Omaha, NE68178, USA.
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167
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Bebbington A, Glasson E, Bourke J, de Klerk N, Leonard H. Hospitalisation rates for children with intellectual disability or autism born in Western Australia 1983-1999: a population-based cohort study. BMJ Open 2013; 3:bmjopen-2012-002356. [PMID: 23449747 PMCID: PMC3586131 DOI: 10.1136/bmjopen-2012-002356] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
OBJECTIVES To describe the hospitalisation patterns in children with intellectual disability (ID) and/or autism spectrum disorder (ASD) after the first year of life and compare with those unaffected. DESIGN Prospective cohort study using data linkage between health, ID and hospitalisation population-based datasets. SETTING Western Australia. PARTICIPANTS 416 611 individuals born between 1983 and 1999 involving 1 027 962 hospital admission records. Five case categories were defined (mild/moderate ID, severe ID, biomedically caused ID, ASD with ID and ASD without ID) and compared with the remainder of children and young people. PRIMARY AND SECONDARY OUTCOME MEASURES Time to event analysis was used to compare time hospitalisation and rate of hospitalisation between the different case-groups by estimating HR, accounting for birth year and preterm birth status. RESULTS ID and/or ASD were found to be associated with an increased risk of hospitalisation compared with the remainder of the population. The increase in risk was highest in those with severe ID and no ASD (HR=10.33, 95% CI 8.66 to 12.31). For those with ID of known biomedical cause or mild ID of unknown cause, the risk of hospitalisation was lower (HR=7.36, 95% CI 6.73 to 8.07 and HR=3.08, 95% CI 2.78 to 3.40, respectively). Those with ASDs had slightly increased risk (HR=2.82, 95% CI 2.26 to 3.50 for those with ID and HR=2.09, 95% CI 1.85 to 2.36 for those without ID). CONCLUSIONS Children with an ID or ASD experience an increased risk of hospitalisation after the first year of life which varied from 2 to 10 times that of the rest of the population. Findings can inform service planning or resource allocation for these children with special needs.
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Affiliation(s)
- Ami Bebbington
- Department of Population Sciences, Telethon Institute for Child Health Research, Centre for Child Health Research, The University of Western Australia, West Perth, Western Australia
| | - Emma Glasson
- Department of Population Sciences, Telethon Institute for Child Health Research, Centre for Child Health Research, The University of Western Australia, West Perth, Western Australia
- School of Population Health Research, The University of Western Australia, West Perth, Western Australia
| | - Jenny Bourke
- Department of Population Sciences, Telethon Institute for Child Health Research, Centre for Child Health Research, The University of Western Australia, West Perth, Western Australia
| | - Nicholas de Klerk
- Department of Population Sciences, Telethon Institute for Child Health Research, Centre for Child Health Research, The University of Western Australia, West Perth, Western Australia
| | - Helen Leonard
- Department of Population Sciences, Telethon Institute for Child Health Research, Centre for Child Health Research, The University of Western Australia, West Perth, Western Australia
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168
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Flore LA, Milunsky JM. Updates in the genetic evaluation of the child with global developmental delay or intellectual disability. Semin Pediatr Neurol 2012; 19:173-80. [PMID: 23245550 DOI: 10.1016/j.spen.2012.09.004] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Global developmental delay (GDD) and intellectual disability (ID) occur in up to 3% of the general population and are even more commonly encountered in the setting of the pediatric neurology clinic. New advances in technology and in the understanding of genetic disorders have led to changes in the diagnostic approach to a child with unexplained GDD or ID. Chromosomal microarray has become a first-line test for evaluation of patients in this population and has both significantly increased diagnostic yield and introduced new challenges in the interpretation of copy number variants of uncertain significance. The G-banded karyotype is now frequently utilized as an adjunct to the microarray rather than as a first-line test in individuals with GDD or ID. Fragile X DNA testing continues to be recommended in the initial evaluation of the child with GDD or ID. The presence or absence of certain cardinal features (such as microcephaly or macrocephaly, seizures, autism, abnormal neurologic examination, and facial dysmorphism) can be utilized to direct single-gene molecular testing. The availability of next-generation and massively parallel sequencing technologies has enabled the use of genetic testing panels, in which dozens of genes associated with GDD or ID may be rapidly analyzed. Most recently, the clinical availability of whole-genome and whole-exome sequencing has opened new possibilities for the evaluation of individuals with GDD or ID who have previously eluded a genetic diagnosis. Consultation with a medical geneticist is recommended when progressing beyond first-tier analyses to most efficiently prioritize testing.
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169
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Neubert G, von Au K, Drossel K, Tzschach A, Horn D, Nickel R, Kaindl AM. Angelman syndrome and severe infections in a patient with de novo 15q11.2-q13.1 deletion and maternally inherited 2q21.3 microdeletion. Gene 2012; 512:453-5. [PMID: 23124039 DOI: 10.1016/j.gene.2012.10.061] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2012] [Revised: 10/02/2012] [Accepted: 10/07/2012] [Indexed: 10/27/2022]
Abstract
Angelman syndrome is a neurodevelopmental disorder characterized by mental retardation, severe speech disorder, facial dysmorphism, secondary microcephaly, ataxia, seizures, and abnormal behaviors such as easily provoked laughter. It is most frequently caused by a de novo maternal deletion of chromosome 15q11-q13 (about 70-90%), but can also be caused by paternal uniparental disomy of chromosome 15q11-q13 (3-7%), an imprinting defect (2-4%) or in mutations in the ubiquitin protein ligase E3A gene UBE3A mostly leading to frame shift mutation. In addition, for patients with overlapping clinical features (Angelman-like syndrome), mutations in methyl-CpG binding protein 2 gene MECP2 and cyclin-dependent kinase-like 5 gene CDKL5 as well as a microdeletion of 2q23.1 including the methyl-CpG binding domain protein 5 gene MBD5 have been described. Here, we describe a patient who carries a de novo 5Mb-deletion of chromosome 15q11.2-q13.1 known to be associated with Angelman syndrome and a further, maternally inherited deletion 2q21.3 (~364kb) of unknown significance. In addition to classic features of Angelman syndrome, she presented with severe infections in the first year of life, a symptom that has not been described in patients with Angelman syndrome. The 15q11.2-q13.1 deletion contains genes critical for Prader-Willi syndrome, the Angelman syndrome causing genes UBE3A and ATP10A/C, and several non-imprinted genes: GABRB3 and GABRA5 (both encoding subunits of GABA A receptor), GOLGA6L2, HERC2 and OCA2 (associated with oculocutaneous albinism II). The deletion 2q21.3 includes exons of the genes RAB3GAP1 (associated with Warburg Micro syndrome) and ZRANB3 (not disease-associated). Despite the normal phenotype of the mother, the relevance of the 2q21.3 microdeletion for the phenotype of the patient cannot be excluded, and further case reports will need to address this point.
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Affiliation(s)
- Gerda Neubert
- Department of Pediatric Neurology, Charité, Universitätsmedizin Berlin, Germany
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170
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171
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Xing L, Hoshijima K, Grunwald DJ, Fujimoto E, Quist TS, Sneddon J, Chien CB, Stevenson TJ, Bonkowsky JL. Zebrafish foxP2 zinc finger nuclease mutant has normal axon pathfinding. PLoS One 2012; 7:e43968. [PMID: 22937139 PMCID: PMC3427223 DOI: 10.1371/journal.pone.0043968] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2011] [Accepted: 07/30/2012] [Indexed: 11/18/2022] Open
Abstract
foxP2, a forkhead-domain transcription factor, is critical for speech and language development in humans, but its role in the establishment of CNS connectivity is unclear. While in vitro studies have identified axon guidance molecules as targets of foxP2 regulation, and cell culture assays suggest a role for foxP2 in neurite outgrowth, in vivo studies have been lacking regarding a role for foxP2 in axon pathfinding. We used a modified zinc finger nuclease methodology to generate mutations in the zebrafish foxP2 gene. Using PCR-based high resolution melt curve analysis (HRMA) of G0 founder animals, we screened and identified three mutants carrying nonsense mutations in the 2(nd) coding exon: a 17 base-pair (bp) deletion, an 8bp deletion, and a 4bp insertion. Sequence analysis of cDNA confirmed that these were frameshift mutations with predicted early protein truncations. Homozygous mutant fish were viable and fertile, with unchanged body morphology, and no apparent differences in CNS apoptosis, proliferation, or patterning at embryonic stages. There was a reduction in expression of the known foxP2 target gene cntnap2 that was rescued by injection of wild-type foxP2 transcript. When we examined axon pathfinding using a pan-axonal marker or transgenic lines, including a foxP2-neuron-specific enhancer, we did not observe any axon guidance errors. Our findings suggest that foxP2 is not necessary for axon pathfinding during development.
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Affiliation(s)
- Lingyan Xing
- Division of Pediatric Neurology, Department of Pediatrics, University of Utah School of Medicine, Salt Lake City, Utah, United States of America
- Department of Neurobiology and Anatomy, University of Utah School of Medicine, Salt Lake City, Utah, United States of America
- Interdepartmental Program in Neurosciences, University of Utah School of Medicine, Salt Lake City, Utah, United States of America
| | - Kazuyuki Hoshijima
- Department of Human Genetics, University of Utah School of Medicine, Salt Lake City, Utah, United States of America
| | - David J. Grunwald
- Department of Human Genetics, University of Utah School of Medicine, Salt Lake City, Utah, United States of America
| | - Esther Fujimoto
- Division of Pediatric Neurology, Department of Pediatrics, University of Utah School of Medicine, Salt Lake City, Utah, United States of America
| | - Tyler S. Quist
- Division of Pediatric Neurology, Department of Pediatrics, University of Utah School of Medicine, Salt Lake City, Utah, United States of America
| | - Jacob Sneddon
- Division of Pediatric Neurology, Department of Pediatrics, University of Utah School of Medicine, Salt Lake City, Utah, United States of America
| | - Chi-Bin Chien
- Department of Neurobiology and Anatomy, University of Utah School of Medicine, Salt Lake City, Utah, United States of America
- Interdepartmental Program in Neurosciences, University of Utah School of Medicine, Salt Lake City, Utah, United States of America
| | - Tamara J. Stevenson
- Division of Pediatric Neurology, Department of Pediatrics, University of Utah School of Medicine, Salt Lake City, Utah, United States of America
| | - Joshua L. Bonkowsky
- Division of Pediatric Neurology, Department of Pediatrics, University of Utah School of Medicine, Salt Lake City, Utah, United States of America
- Department of Neurobiology and Anatomy, University of Utah School of Medicine, Salt Lake City, Utah, United States of America
- Interdepartmental Program in Neurosciences, University of Utah School of Medicine, Salt Lake City, Utah, United States of America
- Department of Neurology, University of Utah School of Medicine, Salt Lake City, Utah, United States of America
- * E-mail:
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172
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Martínez-Noël G, Galligan JT, Sowa ME, Arndt V, Overton TM, Harper JW, Howley PM. Identification and proteomic analysis of distinct UBE3A/E6AP protein complexes. Mol Cell Biol 2012; 32:3095-106. [PMID: 22645313 PMCID: PMC3434508 DOI: 10.1128/mcb.00201-12] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2012] [Accepted: 05/21/2012] [Indexed: 02/01/2023] Open
Abstract
The E6AP ubiquitin ligase catalyzes the high-risk human papillomaviruses' E6-mediated ubiquitylation of p53, contributing to the neoplastic progression of cells infected by these viruses. Defects in the activity and the dosage of E6AP are linked to Angelman syndrome and to autism spectrum disorders, respectively, highlighting the need for precise control of the enzyme. With the exception of HERC2, which modulates the ubiquitin ligase activity of E6AP, little is known about the regulation or function of E6AP normally. Using a proteomic approach, we have identified and validated several new E6AP-interacting proteins, including HIF1AN, NEURL4, and mitogen-activated protein kinase 6 (MAPK6). E6AP exists as part of several different protein complexes, including the proteasome and an independent high-molecular-weight complex containing HERC2, NEURL4, and MAPK6. In examining the functional consequence of its interaction with the proteasome, we found that UBE3C (another proteasome-associated ubiquitin ligase), but not E6AP, contributes to proteasomal processivity in mammalian cells. We also found that E6 associates with the HERC2-containing high-molecular-weight complex through its binding to E6AP. These proteomic studies reveal a level of complexity for E6AP that has not been previously appreciated and identify a number of new cellular proteins through which E6AP may be regulated or functioning.
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Affiliation(s)
- Gustavo Martínez-Noël
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, Massachusetts, USA
| | - Jeffrey T. Galligan
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, Massachusetts, USA
| | - Mathew E. Sowa
- Department of Cell Biology, Harvard Medical School, Boston, Massachusetts, USA
| | - Verena Arndt
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, Massachusetts, USA
| | - Thomas M. Overton
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, Massachusetts, USA
| | - J. Wade Harper
- Department of Cell Biology, Harvard Medical School, Boston, Massachusetts, USA
| | - Peter M. Howley
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, Massachusetts, USA
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173
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Induced pluripotent stem cells to model and treat neurogenetic disorders. Neural Plast 2012; 2012:346053. [PMID: 22888453 PMCID: PMC3409544 DOI: 10.1155/2012/346053] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2012] [Accepted: 05/30/2012] [Indexed: 12/12/2022] Open
Abstract
Remarkable advances in cellular reprogramming have made it possible to generate pluripotent stem cells from somatic cells, such as fibroblasts obtained from human skin biopsies. As a result, human diseases can now be investigated in relevant cell populations derived from induced pluripotent stem cells (iPSCs) of patients. The rapid growth of iPSC technology has turned these cells into multipurpose basic and clinical research tools. In this paper, we highlight the roles of iPSC technology that are helping us to understand and potentially treat neurological diseases. Recent studies using iPSCs to model various neurogenetic disorders are summarized, and we discuss the therapeutic implications of iPSCs, including drug screening and cell therapy for neurogenetic disorders. Although iPSCs have been used in animal models with promising results to treat neurogenetic disorders, there are still many issues associated with reprogramming that must be addressed before iPSC technology can be fully exploited with translation to the clinic.
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174
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Chailangkarn T, Acab A, Muotri AR. Modeling neurodevelopmental disorders using human neurons. Curr Opin Neurobiol 2012; 22:785-90. [PMID: 22717528 DOI: 10.1016/j.conb.2012.04.004] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2012] [Revised: 04/10/2012] [Accepted: 04/11/2012] [Indexed: 12/21/2022]
Abstract
The cellular and molecular mechanisms of neurodevelopmental conditions such as autism spectrum disorders have been studied intensively for decades. The unavailability of live patient neurons for research, however, has represented a major obstacle in the elucidation of the disease etiologies. Recently, the development of induced pluripotent stem cell (iPSC) technology allows for the generation of human neurons from somatic cells of patients. We review ongoing studies using iPSCs as an approach to model neurodevelopmental disorders, the promise and caveats of this technique and its potential for drug screening. The reproducible findings of relevant phenotypes in Rett syndrome iPSC-derived neurons suggest that iPSC technology offers a novel and unique opportunity for the understanding of and the development of therapeutics for other autism spectrum disorders.
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Affiliation(s)
- Thanathom Chailangkarn
- University of California San Diego, School of Medicine, Department of Pediatrics/Rady Children's Hospital San Diego, Department of Cellular & Molecular Medicine, Stem Cell Program, La Jolla, CA 92093, USA
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175
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Abstract
Rett syndrome is one of the most common causes of complex disability in girls. It is characterized by early neurological regression that severely affects motor, cognitive and communication skills, by autonomic dysfunction and often a seizure disorder. It is a monogenic X-linked dominant neurodevelopmental disorder related to mutation in MECP2, which encodes the methyl-CpG-binding protein MeCP2. There are several mouse models either based on conditional knocking out of the Mecp2 gene or on a truncating mutation. We discuss the clinical aspects with special emphasis on the behavioral phenotype and we review current perspectives in clinical management alongside with perspectives in altering gene expression.
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Affiliation(s)
- E E J Smeets
- Department of Clinical Genetics, Maastricht University Medical Center, Maastricht, The Netherlands
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176
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Meng L, Person RE, Beaudet AL. Ube3a-ATS is an atypical RNA polymerase II transcript that represses the paternal expression of Ube3a. Hum Mol Genet 2012; 21:3001-12. [PMID: 22493002 DOI: 10.1093/hmg/dds130] [Citation(s) in RCA: 132] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The Angelman syndrome gene, UBE3A, is subject to genomic imprinting controlled by mechanisms that are only partially understood. Its antisense transcript, UBE3A-ATS, is also imprinted and hypothesized to suppress UBE3A in cis. In this research, we showed that the mouse antisense ortholog, Ube3a-ATS, was transcribed by RNA polymerase (RNAP) II. However, unlike typical protein-coding transcripts, Ube3a-ATS was not poly-adenylated and was localized exclusively in the nucleus. It was relatively unstable with a half-life of 4 h, shorter than most protein-coding RNAs tested. To understand the role of Ube3a-ATS in vivo, a mouse model with a 0.9-kb genomic deletion over the paternal Snrpn major promoter was studied. The mice showed partial activation of paternal Ube3a, with decreased expression of Ube3a-ATS but not any imprinting defects in the Prader-Willi syndrome/Angelman syndrome region. A novel cell culture model was also generated with a transcriptional termination cassette inserted downstream of Ube3a on the paternal chromosome to reduce Ube3a-ATS transcription. In neuronally differentiated embryonic stem (ES) cells, paternal Ube3a was found to be expressed at a high level, comparable with that of the maternal allele. To further characterize the antisense RNA, a strand-specific microarray was performed. Ube3a-ATS was detectable across the entire locus of Ube3a and extended beyond the transcriptional start site of Ube3a. In summary, we conclude that Ube3a-ATS is an atypical RNAPII transcript that represses Ube3a on the paternal chromosome. These results suggest that the repression of human UBE3A-ATS may activate the expression of UBE3A from the paternal chromosome, providing a potential therapeutic strategy for patients with Angelman syndrome.
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Affiliation(s)
- Linyan Meng
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
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177
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Vendrame M, Loddenkemper T, Zarowski M, Gregas M, Shuhaiber H, Sarco DP, Morales A, Nespeca M, Sharpe C, Haas K, Barnes G, Glaze D, Kothare SV. Analysis of EEG patterns and genotypes in patients with Angelman syndrome. Epilepsy Behav 2012; 23:261-5. [PMID: 22341959 DOI: 10.1016/j.yebeh.2011.11.027] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/15/2011] [Revised: 11/14/2011] [Accepted: 11/25/2011] [Indexed: 10/28/2022]
Abstract
We prospectively analyzed EEGs from participants in the ongoing NIH Rare Diseases Clinical Research Network Angelman Syndrome Natural History Study. Of the one-hundred-sixty enrolled patients (2006-2010), 115 had complete data (58 boys, median age 3.6 years). Distinct EEG findings were intermittent rhythmic delta waves (83.5%), interictal epileptiform discharges (74.2%), intermittent rhythmic theta waves (43.5%), and posterior rhythm slowing (43.5%). Centro-occipital and centro-temporal delta waves decreased with age (p=0.01, p=0.03). There were no specific correlations between EEG patterns and genotypes. A classification tree allowed the prediction of deletions class-1 (5.9 Mb) in patients with intermittent theta waves in <50% of EEG and interictal epileptiform abnormalities; UPD, UBE3A mutation or imprinting defects in patients with intermittent theta in <50% of EEG without interictal epileptiform abnormalities; deletions class-2 (5.0 Mb) in patients with >50% theta and normal posterior rhythm; atypical deletions in patients with >50% theta but abnormal posterior rhythm. EEG patterns are important biomarkers in Angelman syndrome and may suggest the underlying genetic etiology.
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Affiliation(s)
- Martina Vendrame
- Boston University, Neurology Department, C-3, Boston, MA 02118, USA
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Novy J, Catarino CB, Chinthapalli K, Smith SM, Clayton-Smith J, Hennekam RCM, Hammond P, Sisodiya SM. Another cause of vaccine encephalopathy: a case of Angelman syndrome. Eur J Med Genet 2012; 55:338-41. [PMID: 22342448 DOI: 10.1016/j.ejmg.2012.01.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2011] [Accepted: 01/17/2012] [Indexed: 10/14/2022]
Abstract
Dravet syndrome has been found recently as an important underlying condition in cases of alleged vaccine encephalopathy after pertussis vaccination, where vaccination seemed to have precipitated the occurrence of the disease without modifying the long-term course. We report on a patient diagnosed with Angelman syndrome in her fifth decade, in whom the intellectual disability and epilepsy had been assumed to be caused by a vaccine encephalopathy following smallpox vaccination. Clinical features of Angelman syndrome had faded away. The history of the present patient suggests that genetic conditions other than Dravet syndrome can be associated with an alleged vaccine encephalopathy. A history of vaccine encephalopathy is rare among patients with learning disability and refractory epilepsy (1.4% in our cohort), but it should lead to consideration of a comprehensive genetic work-up if Dravet syndrome is excluded. The early history of the patient, when available, should guide the investigations. Medico-legal aspects are also discussed.
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Affiliation(s)
- Jan Novy
- Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, University College London, Queen Square, London, UK
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180
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Friedman JM. Using genomics for birth defects epidemiology: can epigenetics cut the GxE Gordian knot? ACTA ACUST UNITED AC 2011; 91:986-9. [PMID: 22140073 DOI: 10.1002/bdra.22875] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2011] [Accepted: 10/03/2011] [Indexed: 12/15/2022]
Abstract
Most birth defects are etiologically complex disorders caused by combinations of genetic and environmental factors, but most studies of birth defect etiology have examined only genetic factors or only environmental factors and have not considered interactions among them. Genome-wide epigenetic studies, which use the same genomic technologies that have revolutionized our ability to identify genetic causes of disease, provide an attractive way to study gene-environment interactions. However, finding an association between epigenetic variation and an etiologically complex birth defect without knowledge of the genetic variation and environmental exposures affecting the individuals who were studied usually provides little or no information regarding the cause of the disorder. In order for genome-wide studies of epigenetic variation to contribute to our understanding of the causes of birth defects, these studies must be combined with studies of environmental exposures and studies of genetic variation in the same subjects. Under such circumstances, epigenetic studies may help to establish the molecular basis for gene-environment interactions.
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181
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Abstract
Happy Puppet syndrome is characterised by a partial deficit of paired autosomal chromosome 15. It is a neuro-genetic disorder characterised by intellectual and developmental delay, sleep disturbance, seizures, jerky movements (especially hand-flapping), frequent laughter or smiling and usually a happy demeanour. It is also called as Angelman syndrome (AS). People with AS are sometimes known as 'angels', both because of the syndrome's name and because of their youthful, happy appearance. A 6.5-year-old girl is presented and clinical suspicion of AS was raised at the age of 4 years when she presented with mental retardation and epilepsy, absence of speech, inability to gait and unprovoked episodes of laughter. Fluorescent in situ hybridisation chromosomal analysis revealed micro deletion on the maternally derived allele of 15q chromosome.
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Affiliation(s)
- Priyanka Airen Sarkar
- Department of Pediatric Dentistry, Modern Dental College and Research Centre, Indore, India.
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182
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Henkhaus RS, Kim SJ, Kimonis VE, Gold JA, Dykens EM, Driscoll DJ, Butler MG. Methylation-specific multiplex ligation-dependent probe amplification and identification of deletion genetic subtypes in Prader-Willi syndrome. Genet Test Mol Biomarkers 2011; 16:178-86. [PMID: 21977908 DOI: 10.1089/gtmb.2011.0115] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
PURPOSE Prader-Willi syndrome (PWS) and Angelman syndrome (AS) are complex neurodevelopmental disorders caused by loss of expression of imprinted genes from the 15q11-q13 region depending on the parent of origin. Methylation-specific multiplex ligation-dependent probe amplification (MS-MLPA) kits from MRC-Holland (Amsterdam, The Netherlands) were used to detect PWS and AS deletion subtypes. We report our experience with two versions of the MS-MLPA-PWS/AS kit (original A1 and newer B1) in determining methylation status and deletion subtypes in individuals with PWS. METHODS MS-MLPA analysis was performed on DNA isolated from a large cohort of PWS subjects with the MS-MLPA-PWS/AS-A1 and -B1 probe sets. RESULTS Both MS-MLPA kits will identify deletions in the 15q11-q13 region but the original MS-MLPA-A1 kit has a higher density of probes at the telomeric end of the 15q11-q13 region, which is more useful for identifying individuals with atypical deletions. The newer B1 kit contains more probes in the imprinting center (IC) and adjoining small noncoding RNAs useful in identifying small microdeletions. CONCLUSION The A1 kit identified the typical deletions and smaller atypical deletions, whereas the B1 kit was more informative for identifying microdeletions including the IC and SNORD116 regions. Both kits should be made available for accurate characterization of PWS/AS deletion subtypes as well as evaluating for IC and SNORD116 microdeletions.
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Affiliation(s)
- Rebecca S Henkhaus
- Department of Psychiatry and Behavioral Sciences and Pediatrics, University of Kansas Medical Center, Kansas City, Kansas 66160, USA
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183
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Abstract
Prader-Willi syndrome is characterized by severe infantile hypotonia with poor suck and failure to thrive; hypogonadism causing genital hypoplasia and pubertal insufficiency; characteristic facial features; early-childhood onset obesity and hyperphagia; developmental delay/mild intellectual disability; short stature; and a distinctive behavioral phenotype. Sleep abnormalities and scoliosis are common. Growth hormone insufficiency is frequent, and replacement therapy provides improvement in growth, body composition, and physical attributes. Management is otherwise largely supportive. Consensus clinical diagnostic criteria exist, but diagnosis should be confirmed through genetic testing. Prader-Willi syndrome is due to absence of paternally expressed imprinted genes at 15q11.2-q13 through paternal deletion of this region (65-75% of individuals), maternal uniparental disomy 15 (20-30%), or an imprinting defect (1-3%). Parent-specific DNA methylation analysis will detect >99% of individuals. However, additional genetic studies are necessary to identify the molecular class. There are multiple imprinted genes in this region, the loss of which contribute to the complete phenotype of Prader-Willi syndrome. However, absence of a small nucleolar organizing RNA gene, SNORD116, seems to reproduce many of the clinical features. Sibling recurrence risk is typically <1%, but higher risks may pertain in certain cases. Prenatal diagnosis is available.
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184
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Lemak A, Yee A, Bezsonova I, Dhe-Paganon S, Arrowsmith CH. Zn-binding AZUL domain of human ubiquitin protein ligase Ube3A. JOURNAL OF BIOMOLECULAR NMR 2011; 51:185-190. [PMID: 21947926 DOI: 10.1007/s10858-011-9552-y] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2011] [Accepted: 06/22/2011] [Indexed: 05/31/2023]
Abstract
Ube3A (also referred to as E6AP for E6 Associated Protein) is a E3 ubiquitin-protein ligase implicated in the development of Angelman syndrome by controlling degradation of synaptic protein Arc and oncogenic papilloma virus infection by controlling degradation of p53. This article describe the solution NMR structure of the conserved N-terminal domain of human Ube3A (residues 24-87) that contains two residues (Cys44 and Arg62) found to be mutated in patients with Angelman syndrome. The structure of this domain adopts a novel Zn-binding fold we called AZUL (Amino-terminal Zn-finger of Ube3a Ligase). The AZUL domain has a helix-loop-helix architecture with a Zn ion coordinated by four Cys residues arranged in Cys-X(4)-Cys-X(4)-Cys-X(28)-Cys motif. Three of the Zn-bound residues are located in a 23-residue long and well structured loop that connects two α-helicies.
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Affiliation(s)
- Alexander Lemak
- Ontario Cancer Institute, Campbell Family Cancer Research Institute and Department of Medical Biophysics, University of Toronto, and Northeast Structural Genomics Consortium, 101 College Street, Toronto, ON M5G 1L7, Canada
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185
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Yuen RKC, Manokhina I, Robinson WP. Are we ready for DNA methylation-based prenatal testing? Epigenomics 2011; 3:387-90. [PMID: 22126197 DOI: 10.2217/epi.11.62] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Affiliation(s)
- Ryan KC Yuen
- Department of Medical Genetics, University of British Columbia, Child & Family Research Institute, 950 West 28th Avenue, Vancouver, BC, V5Z 4H4, Canada
| | - Irina Manokhina
- Department of Medical Genetics, University of British Columbia, Child & Family Research Institute, 950 West 28th Avenue, Vancouver, BC, V5Z 4H4, Canada
| | - Wendy P Robinson
- Department of Medical Genetics, University of British Columbia, Child & Family Research Institute, 950 West 28th Avenue, Vancouver, BC, V5Z 4H4, Canada
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186
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Dagli A, Buiting K, Williams CA. Molecular and Clinical Aspects of Angelman Syndrome. Mol Syndromol 2011; 2:100-112. [PMID: 22670133 DOI: 10.1159/000328837] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The Angelman syndrome is caused by disruption of the UBE3A gene and is clinically delineated by the combination of severe mental disability, seizures, absent speech, hypermotoric and ataxic movements, and certain remarkable behaviors. Those with the syndrome have a predisposition toward apparent happiness and paroxysms of laughter, and this finding helps distinguish Angelman syndrome from other conditions involving severe developmental handicap. Accurate diagnosis rests on a combination of clinical criteria and molecular and/or cytogenetic testing. Analysis of parent-specific DNA methylation imprints in the critical 15q11.2-q13 genomic region identifies 75-80% of all individuals with the syndrome, including those with cytogenetic deletions, imprinting center defects and paternal uniparental disomy. In the remaining group, UBE3A sequence analysis identifies an additional percentage of patients, but 5-10% will remain who appear to have the major clinical phenotypic features but do not have any identifiable genetic abnormalities. Genetic counseling for recurrence risk is complicated because multiple genetic mechanisms can disrupt the UBE3A gene, and there is also a unique inheritance pattern associated with UBE3A imprinting. Angelman syndrome is a prototypical developmental syndrome due to its remarkable behavioral phenotype and because UBE3A is so crucial to normal synaptic function and neural plasticity.
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Affiliation(s)
- A Dagli
- Raymond C. Philips Unit, Division of Genetics and Metabolism, Department of Pediatrics, University of Florida, Gainesville, Fla., USA
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187
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Piedrahita JA. The role of imprinted genes in fetal growth abnormalities. ACTA ACUST UNITED AC 2011; 91:682-92. [PMID: 21648055 DOI: 10.1002/bdra.20795] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2010] [Revised: 12/13/2010] [Accepted: 01/26/2011] [Indexed: 12/20/2022]
Abstract
Epigenetics, and in particular imprinted genes, have a critical role in the development and function of the placenta, which in turn has a central role in the regulation of fetal growth and development. A unique characteristic of imprinted genes is their expression from only one allele, maternal or paternal and dependent on parent of origin. This unique expression pattern may have arisen as a mechanism to control the flow of nutrients from the mother to the fetus, with maternally expressed imprinted genes reducing the flow of resources and paternally expressed genes increasing resources to the fetus. As a result, any epigenetic deregulation affecting this balance can result in fetal growth abnormalities. Imprinting-associated disorders in humans, such as Beckwith-Wiedemann and Angelman syndrome, support the role of imprinted genes in fetal growth. Similarly, assisted reproductive technologies in animals have been shown to affect the epigenome of the early embryo and the expression of imprinted genes. Their role in disorders such as intrauterine growth restriction appears to be more complex, in that imprinted gene expression can be seen as both causative and protective of fetal growth restriction. This protective or compensatory effect needs to be explored more fully.
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Affiliation(s)
- Jorge A Piedrahita
- Department of Molecular Biomedical Sciences and Center for Comparative Medicine and Translational Research, North Carolina State University, 4700 Hillsborough Street, Raleigh, NC 27606, USA.
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188
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Establishment of the first WHO international genetic reference panel for Prader Willi and Angelman syndromes. Eur J Hum Genet 2011; 19:857-64. [PMID: 21587322 DOI: 10.1038/ejhg.2011.59] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Prader Willi and Angelman syndromes are clinically distinct genetic disorders both mapping to chromosome region 15q11-q13, which are caused by a loss of function of paternally or maternally inherited genes in the region, respectively. With clinical diagnosis often being difficult, particularly in infancy, confirmatory genetic diagnosis is essential to enable clinical intervention. However, the latter is challenged by the complex genetics behind both disorders and the unmet need for characterised reference materials to aid accurate molecular diagnosis. With this in mind, a panel of six genotyping reference materials for Prader Willi and Angelman syndromes was developed, which should be stable for many years and available to all diagnostic laboratories. The panel comprises three Prader Willi syndrome materials (two with different paternal deletions, and one with maternal uniparental disomy (UPD)) and three Angelman syndrome materials (one with a maternal deletion, one with paternal UPD or an epigenetic imprinting centre defect, and one with a UBE3A point mutation). Genomic DNA was bulk-extracted from Epstein-Barr virus-transformed lymphoblastoid cell lines established from consenting patients, and freeze-dried as aliquots in glass ampoules. In total, 37 laboratories from 26 countries participated in a collaborative study to assess the suitability of the panel. Participants evaluated the blinded, triplicate materials using their routine diagnostic methods against in-house controls or externally sourced uncertified reference materials. The panel was established by the Expert Committee on Biological Standardization of the World Health Organization as the first International Genetic Reference Panel for Prader Willi and Angelman syndromes.
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189
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Gatto CL, Broadie K. Drosophila modeling of heritable neurodevelopmental disorders. Curr Opin Neurobiol 2011; 21:834-41. [PMID: 21596554 DOI: 10.1016/j.conb.2011.04.009] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2011] [Revised: 04/08/2011] [Accepted: 04/25/2011] [Indexed: 11/16/2022]
Abstract
Heritable neurodevelopmental disorders are multifaceted disease conditions encompassing a wide range of symptoms including intellectual disability, cognitive dysfunction, autism and myriad other behavioral impairments. In cases where single, causative genetic defects have been identified, such as Angelman syndrome, Rett syndrome, Neurofibromatosis Type 1 and Fragile X syndrome, the classical Drosophila genetic system has provided fruitful disease models. Recent Drosophila studies have advanced our understanding of UBE3A, MECP2, NF1 and FMR1 function, respectively, in genetic, biochemical, anatomical, physiological and behavioral contexts. Investigations in Drosophila continue to provide the essential mechanistic understanding required to facilitate the conception of rational therapeutic treatments.
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Affiliation(s)
- Cheryl L Gatto
- Departments of Biological Sciences and Cell and Developmental Biology, Kennedy Center for Research on Human Development, Vanderbilt University, Nashville, TN 37232, USA
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190
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Mabb AM, Judson MC, Zylka MJ, Philpot BD. Angelman syndrome: insights into genomic imprinting and neurodevelopmental phenotypes. Trends Neurosci 2011; 34:293-303. [PMID: 21592595 DOI: 10.1016/j.tins.2011.04.001] [Citation(s) in RCA: 183] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2011] [Revised: 03/25/2011] [Accepted: 04/05/2011] [Indexed: 10/24/2022]
Abstract
Angelman syndrome (AS) is a severe genetic disorder caused by mutations or deletions of the maternally inherited UBE3A gene. UBE3A encodes an E3 ubiquitin ligase that is expressed biallelically in most tissues but is maternally expressed in almost all neurons. In this review, we describe recent advances in understanding the expression and function of UBE3A in the brain and the etiology of AS. We highlight current AS model systems, epigenetic mechanisms of UBE3A regulation, and the identification of potential UBE3A substrates in the brain. In the process, we identify major gaps in our knowledge that, if bridged, could move us closer to identifying treatments for this debilitating neurodevelopmental disorder.
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Affiliation(s)
- Angela M Mabb
- Department of Cell and Molecular Physiology, UNC Neuroscience Center, University of North Carolina, Chapel Hill, NC 27599, USA
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191
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Butler MG. Prader-Willi Syndrome: Obesity due to Genomic Imprinting. Curr Genomics 2011; 12:204-15. [PMID: 22043168 PMCID: PMC3137005 DOI: 10.2174/138920211795677877] [Citation(s) in RCA: 174] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2011] [Revised: 03/01/2011] [Accepted: 03/01/2011] [Indexed: 11/22/2022] Open
Abstract
Prader-Willi syndrome (PWS) is a complex neurodevelopmental disorder due to errors in genomic imprinting with loss of imprinted genes that are paternally expressed from the chromosome 15q11-q13 region. Approximately 70% of individuals with PWS have a de novo deletion of the paternally derived 15q11-q13 region in which there are two subtypes (i.e., larger Type I or smaller Type II), maternal disomy 15 (both 15s from the mother) in about 25% of cases, and the remaining subjects have either defects in the imprinting center controlling the activity of imprinted genes or due to other chromosome 15 rearrangements. PWS is characterized by a particular facial appearance, infantile hypotonia, a poor suck and feeding difficulties, hypogonadism and hypogenitalism in both sexes, short stature and small hands and feet due to growth hormone deficiency, mild learning and behavioral problems (e.g., skin picking, temper tantrums) and hyperphagia leading to early childhood obesity. Obesity is a significant health problem, if uncontrolled. PWS is considered the most common known genetic cause of morbid obesity in children. The chromosome 15q11-q13 region contains approximately 100 genes and transcripts in which about 10 are imprinted and paternally expressed. This region can be divided into four groups: 1) a proximal non-imprinted region; 2) a PWS paternal-only expressed region containing protein-coding and non-coding genes; 3) an Angelman syndrome region containing maternally expressed genes and 4) a distal non-imprinted region. This review summarizes the current understanding of the genetic causes, the natural history and clinical presentation of individuals with PWS.
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Affiliation(s)
- Merlin G Butler
- Departments of Psychiatry & Behavioral Sciences and Pediatrics, Kansas University Medical Center, Kansas City, Kansas, USA
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192
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Abstract
Chromosome imbalances are the leading cause of intellectual and developmental disabilities in the population. This paper reviews the current methods used to diagnose chromosome abnormalities in children including karyotyping, fluorescence in situ hybridization and microarray technologies. Advances in molecular cytogenetics, especially with the use of microarrays, have substantially increased the detection of chromosome abnormalities in children with disabilities and congenital anomalies above that achievable with conventional cytogenetic banding and light microscopy.
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193
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Beleza-Meireles A, Cerqueira R, Sousa SB, Palmeiro A, Ramos L. Novel deletion encompassing exons 5-12 of the UBE3A gene in a girl with Angelman syndrome. Eur J Med Genet 2011; 54:348-50. [PMID: 21397058 DOI: 10.1016/j.ejmg.2011.02.010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2010] [Accepted: 02/24/2011] [Indexed: 01/22/2023]
Abstract
Angelman syndrome (AS) is characterised by severe developmental delay, severe speech impairment, gait ataxia and/or limb tremor and a unique behavioural phenotype. The diagnosis of AS is based on a combination of clinical features and molecular genetic testing. Currently, molecular genetic testing (methylation analysis and UBE3A sequence analysis) identifies anomalies in about 90% of individuals. The aetiology of the remaining 10% is still unknown. We report a novel deletion encompassing the exons 5-12 of the UBE3A gene in a girl with AS, identified by MLPA (Multiplex Ligation-dependent Probe Amplification), which was not detected by the conventional diagnostic protocol. We propose that copy number analysis of the UBE3A gene should be considered in individuals whose clinical examination is strongly suggestive of AS, after more common mechanisms have been excluded.
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Affiliation(s)
- Ana Beleza-Meireles
- Department of Clinical Genetics, Coimbra Paediatrics Hospital, Coimbra 3000-076, Portugal.
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194
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Kotulska K, Jóźwiak S. Autism in monogenic disorders. Eur J Paediatr Neurol 2011; 15:177-80. [PMID: 20920867 DOI: 10.1016/j.ejpn.2010.08.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/26/2010] [Accepted: 08/31/2010] [Indexed: 12/15/2022]
Affiliation(s)
- Katarzyna Kotulska
- Department of Neurology and Epileptology, The Children's Memorial Health Institute, Al. Dzieci Polskich 20, 04-730 Warsaw, Poland.
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195
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Allensworth M, Saha A, Reiter LT, Heck DH. Normal social seeking behavior, hypoactivity and reduced exploratory range in a mouse model of Angelman syndrome. BMC Genet 2011; 12:7. [PMID: 21235769 PMCID: PMC3025901 DOI: 10.1186/1471-2156-12-7] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2010] [Accepted: 01/14/2011] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Angelman syndrome (AS) is a neurogenetic disorder characterized by severe developmental delay with mental retardation, a generally happy disposition, ataxia and characteristic behaviors such as inappropriate laughter, social-seeking behavior and hyperactivity. The majority of AS cases are due to loss of the maternal copy of the UBE3A gene. Maternal Ube3a deficiency (Ube3a m-/p+), as well as complete loss of Ube3a expression (Ube3a m-/p-), have been reproduced in the mouse model used here. RESULTS Here we asked if two characteristic AS phenotypes - social-seeking behavior and hyperactivity - are reproduced in the Ube3a deficient mouse model of AS. We quantified social-seeking behavior as time spent in close proximity to a stranger mouse and activity as total time spent moving during exploration, movement speed and total length of the exploratory path. Mice of all three genotypes (Ube3a m+/p+, Ube3a m-/p+, Ube3a m-/p-) were tested and found to spend the same amount of time in close proximity to the stranger, indicating that Ube3a deficiency in mice does not result in increased social seeking behavior or social dis-inhibition. Also, Ube3a deficient mice were hypoactive compared to their wild-type littermates as shown by significantly lower levels of activity, slower movement velocities, shorter exploratory paths and a reduced exploratory range. CONCLUSIONS Although hyperactivity and social-seeking behavior are characteristic phenotypes of Angelman Syndrome in humans, the Ube3a deficient mouse model does not reproduce these phenotypes in comparison to their wild-type littermates. These phenotypic differences may be explained by differences in the size of the genetic defect as ~70% of AS patients have a deletion that includes several other genes surrounding the UBE3A locus.
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Affiliation(s)
- Melody Allensworth
- Department of Anatomy and Neurobiology, University of Tennessee Health Science Center, Memphis, TN 38139, USA
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196
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Philpot BD, Thompson CE, Franco L, Williams CA. Angelman syndrome: advancing the research frontier of neurodevelopmental disorders. J Neurodev Disord 2010; 3:50-6. [PMID: 21484597 PMCID: PMC3163993 DOI: 10.1007/s11689-010-9066-z] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/12/2010] [Accepted: 11/08/2010] [Indexed: 11/25/2022] Open
Abstract
This report is a meeting summary of the 2010 Angelman Syndrome Foundation's scientific symposium on the neuroscience of UBE3A. Angelman syndrome is characterized by loss of speech, severe developmental delay, seizures, and ataxia. These core symptoms are caused by maternal allele disruptions of a single gene-UBE3A. UBE3A encodes an E3 ubiquitin ligase that targets certain proteins for proteasomal degradation. This biology has led to the expectation that the identification of Ube3a protein targets will lead to therapies for Angelman syndrome. The recent discovery of Ube3a substrates such as Arc (activity-regulated cytoskeletal protein) provides new insight into the mechanisms underlying the synaptic function and plasticity deficits caused by the loss of Ube3a. In addition to identifying Ube3a substrates, there have also been recent advances in understanding UBE3A's integrated role in the neuronal repertoire of genes and protein interactions. A developmental picture is now emerging whereby UBE3A gene dosage on chromosome 15 alters synaptic function, with deficiencies leading to Angelman syndrome and overexpression associated with classic autism symptomatology.
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Affiliation(s)
- Benjamin D. Philpot
- Department of Cell and Molecular Physiology, Neuroscience Center, and Carolina Institute for Developmental Disabilities, University of North Carolina, Chapel Hill, NC USA
- Scientific Advisory Committee, Angelman Treatment and Research Institute, Angelman Syndrome Foundation, Aurora, IL USA
| | - Coral E. Thompson
- Scientific Advisory Committee, Angelman Treatment and Research Institute, Angelman Syndrome Foundation, Aurora, IL USA
| | - Lisa Franco
- Scientific Advisory Committee, Angelman Treatment and Research Institute, Angelman Syndrome Foundation, Aurora, IL USA
| | - Charles A. Williams
- Scientific Advisory Committee, Angelman Treatment and Research Institute, Angelman Syndrome Foundation, Aurora, IL USA
- Raymond C. Philips Unit, Division of Genetics and Metabolism, Department of Pediatrics, University of Florida College of Medicine, Gainesville, FL USA
- P.O. Box 100296, HSC, Gainesville, FL 32610 USA
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