A placebo-controlled trial of folic acid and betaine in identical twins with Angelman syndrome

Abstract Background Angelman syndrome (AS) is a neurodevelopmental disorder that is caused by maternal genetic deficiency of a gene that encodes E6-AP ubiquitin-protein ligase (gene symbol UBE3A) mapping to chromosome 15q11-q13. AS leads to stiff and jerky gait, excess laughter, seizures, and severe intellectual disability. In some parts of the brain, the paternally inherited UBE3A gene is subject to genomic imprinting by the action of the UBE3A-antisense transcript (UBE3A-ATS) on the paternally inherited allele. Consequently, only the maternally inherited UBE3A gene is expressed in mature neurons. AS occurs due to deletions of the maternal 15q11 − 13 region, paternal uniparental disomy (UPD), imprinting center defects, mutations in the maternal UBE3A gene, or other unknown genetic malfunctions that result in a silenced maternal UBE3A gene in the specific imprinted regions of the brain. Results A potential treatment strategy for AS is to increase methylation of UBE3A-ATS to promote expression of the paternal UBE3A gene and thus ameliorate the clinical phenotypes of AS. We treated two sets of male identical twins with class I deletions with a 1 year treatment trial of either betaine and folic acid versus placebo. We found no statistically significant changes in the clinical parameters tested at the end of the 1 year trial, nor did we find any significant adverse events. Conclusions This study tested the hypothesis that by increasing the methylation of the UBE3A-antisense transcript in Angelman syndrome to promote expression of the silenced paternal UBE3A gene we may ameliorate the clinical phenotypes of AS. We treated two sets of identical twins with placebo versus betaine and folic acid. Although this study represented a novel approach to treating Angelman syndrome, the differences in the developmental testing results was not significant. This paper also discusses the value of monozygotic twin studies in minimizing confounding variables and its utility in conducting small treatment studies. Trial registration NCT00348933. Registered 6 July 2006.

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BIOLOGICAL SCIENCES: Genetics

10.1101/404061 ◽

2018 ◽

Author(s):

Jack S. Hsiao ◽

Noelle D. Germain ◽

Andrea Wilderman ◽

Christopher Stoddard ◽

Luke A. Wojenski ◽

...

Keyword(s):

Boundary Element ◽

Angelman Syndrome ◽

Antisense Transcript ◽

Neurodevelopmental Disorder ◽

Boundary Function ◽

Paternal Allele ◽

Loss Of Function ◽

Maternal Allele ◽

Specific Expression ◽

Human Neurons

ABSTRACTAngelman syndrome (AS) is a severe neurodevelopmental disorder caused by the loss of function from the maternal allele of UBE3A, a gene encoding an E3 ubiquitin ligase. UBE3A is only expressed from the maternally-inherited allele in mature human neurons due to tissue-specific genomic imprinting. Imprinted expression of UBE3A is restricted to neurons by expression of UBE3A antisense transcript (UBE3A-ATS) from the paternally-inherited allele, which silences the paternal allele of UBE3A in cis. However, the mechanism restricting UBE3A-ATS expression and UBE3A imprinting to neurons is not understood. We used CRISPR/Cas9-mediated genome editing to functionally define a bipartite boundary element critical for neuron-specific expression of UBE3A-ATS in humans. Removal of this element led to upregulation of UBE3A-ATS without repressing paternal UBE3A. However, increasing expression of UBE3A-ATS in the absence of the boundary element resulted in full repression of paternal UBE3A, demonstrating that UBE3A imprinting requires both the loss of function from the boundary element as well as upregulation of UBE3A-ATS. These results suggest that manipulation of the competition between UBE3A-ATS and UBE3A may provide a potential therapeutic approach for AS.SIGNIFICANCE STATEMENTAngelman syndrome is a neurodevelopmental disorder caused by loss of function from the maternal allele of UBE3A, an imprinted gene. The paternal allele of UBE3A is silenced by a long, non-coding antisense transcript in mature neurons. We have identified a boundary element that stops the transcription of the antisense transcript in human pluripotent stem cells, and thus restricts UBE3A imprinted expression to neurons. We further determined that UBE3A imprinting requires both the loss of the boundary function and sufficient expression of the antisense transcript to silence paternal UBE3A. These findings provide essential details about the mechanisms of UBE3A imprinting that may suggest additional therapeutic approaches for Angelman syndrome.

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Angelman Syndrome: A Rare Case Report

UNIVERSITY JOURNAL OF DENTAL SCIENCES ◽

10.21276/ujds.2020.6.2.8 ◽

2020 ◽

Vol 6 (2) ◽

pp. 79-82

Author(s):

Balkrishn Gaur ◽

Gopa Kumar R. Nair ◽

Vinay Mohan ◽

Suneel Kumar Gupta

Keyword(s):

Angelman Syndrome ◽

Neurodevelopmental Disorder ◽

Brain Magnetic Resonance Imaging ◽

Screening Tests ◽

Speech Delay ◽

Resonance Imaging ◽

Severe Intellectual Disability ◽

Rare Case Report ◽

Metabolic Screening ◽

Magnetic Resonance Imaging Mri

Angelman syndrome (AS) is a rare neurodevelopmental disorder characterized by severe intellectual disability, speech delay, dysmorphic features, cognitive impairment, seizures as well as a unique behaviour with an inappropriate happy demeanor. This article discuss the case of an eight year old male patient with the chief complain of dental pain but presented with the signs of AS. He appeared hyperactive and easily excitable with an unusual laughing facial expression. His speech was impaired and showed unusual fascination towards water. Metabolic screening tests and brain Magnetic Resonance Imaging (MRI) revealed no abnormality. Genetic analysis is pathognomonic for Angelman Syndrome.

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Imprinting effects of UBE3A loss on synaptic gene networks and Wnt signaling pathways

10.1101/649491 ◽

2019 ◽

Author(s):

S. Jesse Lopez ◽

Benjamin I. Laufer ◽

Ulrika Beitnere ◽

Elizabeth L. Berg ◽

Jill L. Silverman ◽

...

Keyword(s):

Systems Biology ◽

Wnt Signaling ◽

Mouse Models ◽

Rat Model ◽

Angelman Syndrome ◽

Gene Networks ◽

Neurodevelopmental Disorder ◽

Postnatal Brain ◽

Parent Of Origin ◽

The Brain

AbstractThe genomically imprinted UBE3A gene encodes a E3 ubiquitin ligase whose loss from the maternal allele leads to the neurodevelopmental disorder Angelman syndrome. However, the mechanisms by which loss of maternal UBE3A contribute to severe neurodevelopmental phenotypes are poorly understood. Previous studies of UBE3A function have focused on mouse models or single targets, but these approaches do not accurately reflect the complexity of imprinted gene networks in the brain nor the systems-level cognitive dysfunctions in Angelman syndrome. We therefore utilized a systems biology approach to better elucidate how UBE3A loss impacts the early postnatal brain in a novel CRISPR/Cas9 engineered rat Angelman model of a complete Ube3a deletion. Strand-specific transcriptome analysis of offspring derived from maternally or paternally inherited Ube3a deletions revealed the expected parental expression patterns of Ube3a sense and antisense transcripts by postnatal day 2 (P2) in hypothalamus and day 9 (P9) in cortex, when compared to wild-type sex-matched littermates. The dependency of genome-wide effects on parent-of-origin, Ube3a genotype, and time (P2, P9) was investigated through transcriptome (RNA-seq of cortex and hypothalamus) and methylome (whole genome bisulfite sequencing of hypothalamus). Weighted gene co-expression and co-methylation network analyses identified co-regulated networks in maternally inherited Ube3a deletion offspring correlated with postnatal age that were enriched in developmental processes including Wnt signaling, synaptic regulation, neuronal and glial functions, epigenetic regulation, ubiquitin, circadian entrainment, and splicing. Furthermore, using this novel rat model, we showed that loss of the paternally expressed Ube3a antisense transcript resulted inboth unique and overlapping dysregulated gene pathways, predominantly at the level of differential methylation, when compared to loss of maternal Ube3a. Together, these results provide the most holistic examination to date of the molecular impacts of UBE3A loss in brain, supporting the existence of interactive epigenetic networks between maternal and paternal transcripts at the Ube3a locus.Author SummaryThe neurodevelopmental disorder Angelman syndrome is caused by loss of UBE3A from the maternal chromosome. UBE3A is a genomically imprinted gene, which results in parent-of-origin specific expression of a protein from the mother and a noncoding RNA from the father. While mouse models have been useful in investigating diverse roles for UBE3A, their partial mutations are of limited utility for investigating parental imprinting effects or identifying a complete list of downstream differences in gene pathways relevant to developing therapies for Angelman syndrome. To address this limitation, we utilized a novel rat model with a CRISPR/Cas9 engineered full UBE3A deletion and systems biology approaches to better understand how UBE3A loss affects early postnatal brain development. We discovered that UBE3A loss has widespread effects on many important neuronal and cellular pathways and uncovered interesting interactions between maternal and paternal genes that were not previously considered. Taken together, our findings provide the most comprehensive view of UBE3A’s influences in the brain, which are relevant to the understanding and development of treatments for Angelman syndrome and related neurodevelopmental disorders.

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Angelman Syndrome-Affected Individual with a Numerically Normal Karyotype and Isodisomic Paternal Uniparental Disomy of Chromosome 15 due to Maternal Robertsonian Translocation (14;15) by Monosomy Rescue

Cytogenetic and Genome Research ◽

10.1159/000490838 ◽

2018 ◽

Vol 156 (1) ◽

pp. 9-13 ◽

Cited By ~ 1

Author(s):

Nuria C. Bramswig ◽

Karin Buiting ◽

Natalie Bechtel ◽

Bernhard Horsthemke ◽

Kevin Rostasy ◽

...

Keyword(s):

Angelman Syndrome ◽

Robertsonian Translocation ◽

Chromosome Region ◽

Neurodevelopmental Disorder ◽

Uniparental Disomy ◽

Normal Karyotype ◽

Early Embryo ◽

Affected Individual ◽

Chromosome 15 ◽

Paternal Uniparental Disomy

Angelman syndrome (AS) is a neurodevelopmental disorder caused by deletion of the maternally inherited 15q11q13 region, paternal uniparental disomy 15 [upd(15)pat], an imprinting defect of the maternal chromosome region 15q11q13, or a pathogenic mutation of the maternal UBE3A allele. Predisposing factors for upd(15)pat, such as nonhomologous robertsonian translocation involving chromosome 15, have been discussed, but no evidence for this predisposition has been published. In the present study, chromosomal analysis was performed in a child with AS, both parents, and the maternal grandparents. Methylation-specific multiplex ligation-dependent probe amplification (MS-MLPA) was employed on DNA of the index individual, and microsatellite analysis was carried out on DNA of the index individual and his parents. The cytogenetic analysis showed that the mother and maternal grandfather are carriers of a rob(14;15). The index individual has a numerically normal karyotype, but MS-MLPA and microsatellite analyses confirmed the clinical diagnosis of AS and revealed a pattern highly suggestive of isodisomic upd(15)pat. This is the first report of an AS-affected individual with isodisomic upd(15)pat and a numerically normal karyotype that most likely results from a rob(14;15)-associated meiotic error in the maternal germline followed by monosomy 15 rescue in the early embryo.

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Genotype–Phenotype Correlations in Angelman Syndrome

Genes ◽

10.3390/genes12070987 ◽

2021 ◽

Vol 12 (7) ◽

pp. 987

Author(s):

Lili Yang ◽

Xiaoli Shu ◽

Shujiong Mao ◽

Yi Wang ◽

Xiaonan Du ◽

...

Keyword(s):

Angelman Syndrome ◽

Cognitive Skills ◽

Molecular Mechanisms ◽

Uniparental Disomy ◽

Treatment Modalities ◽

Global Developmental Delay ◽

Loss Of Function ◽

Neurodevelopmental Disease ◽

Severe Intellectual Disability ◽

New Treatment

Angelman syndrome (AS) is a rare neurodevelopmental disease that is caused by the loss of function of the maternal copy of ubiquitin–protein ligase E3A (UBE3A) on the chromosome 15q11–13 region. AS is characterized by global developmental delay, severe intellectual disability, lack of speech, happy disposition, ataxia, epilepsy, and distinct behavioral profile. There are four molecular mechanisms of etiology: maternal deletion of chromosome 15q11–q13, paternal uniparental disomy of chromosome 15q11–q13, imprinting defects, and maternally inherited UBE3A mutations. Different genetic types may show different phenotypes in performance, seizure, behavior, sleep, and other aspects. AS caused by maternal deletion of 15q11–13 appears to have worse development, cognitive skills, albinism, ataxia, and more autistic features than those of other genotypes. Children with a UBE3A mutation have less severe phenotypes and a nearly normal development quotient. In this review, we proposed to review genotype–phenotype correlations based on different genotypes. Understanding the pathophysiology of the different genotypes and the genotype–phenotype correlations will offer an opportunity for individualized treatment and genetic counseling. Genotype–phenotype correlations based on larger data should be carried out for identifying new treatment modalities.

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Molecular-Genetic Diagnostics of Angelman Syndrome – The Bulgarian Experience

Acta Medica Bulgarica ◽

10.2478/amb-2020-0002 ◽

2020 ◽

Vol 47 (1) ◽

pp. 9-16

Author(s):

B. Georgieva ◽

S. Atemin ◽

A. Todorova ◽

T. Todorov ◽

A. Miteva ◽

...

Keyword(s):

Clinical Diagnosis ◽

Angelman Syndrome ◽

Molecular Mechanisms ◽

Neurodevelopmental Disorder ◽

Molecular Genetic ◽

Regulatory Region ◽

Uniparental Disomy ◽

Pcr Multiplex ◽

Ube3a Gene ◽

Mechanisms Of Mutagenesis

AbstractObjective: The aim of the study was to determine the molecular mechanisms of mutagenesis in Bulgarian patients with Angelman syndrome (AS). AS is a severe neurodevelopmental disorder caused by loss of expression in brain of the maternally inherited UBE3A gene as a result of various 15q11.2-q13 alterations.Material and Methods: In total 24 patients (11 boys, 13 girls) from 22 unrelated families with suspected clinical diagnosis AS were analysed. We used methylation specific PCR, multiplex ligation-dependent probe amplification, methylation sensitive MLPA, and direct sequencing of the UBE3A gene.Results: In 9 families (41%) pathogenic mutations were detected, which confirmed the clinical diagnosis on а molecular-genetic level. In 4 (44%) of these families we found 15q11-q13 region deletion with breakpoints BP1-BP3 or BP2-BP3. In 1 (11%) of the families we found imprinting defect: deletion of the AS-SRO regulatory region (part of the PWS-AS imprinting center). In 1 (11%) of the families we detected a rare finding – paternal uniparental disomy of chromosome 15. In 3 (33%) of the families diff erent point mutations in the UBE3A gene were detected: two novel missence mutations c.488T > C; p.Leu163Ser and c.1832A > T; p.Gln611Leu, and one known frameshift mutation c.2576_2579delAAGA; p.Lys859Argfs*4.Conclusion: The obtained results helped us to develop a systematic diagnostic algorithm in order to provide proper diagnosis for the patients with AS. Combining excellent knowledge of the molecular mechanisms of mutagenesis and proper molecular-genetic testing approaches is a cornerstone in the management of AS patients, ensuring AS families would receive both adequate genetic counseling and prophylaxis of the disease in the future.

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