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Tokunaga M, Imamura T. Emerging concepts involving inhibitory and activating RNA functionalization towards the understanding of microcephaly phenotypes and brain diseases in humans. Front Cell Dev Biol 2023; 11:1168072. [PMID: 37408531 PMCID: PMC10318543 DOI: 10.3389/fcell.2023.1168072] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Accepted: 06/12/2023] [Indexed: 07/07/2023] Open
Abstract
Microcephaly is characterized as a small head circumference, and is often accompanied by developmental disorders. Several candidate risk genes for this disease have been described, and mutations in non-coding regions are occasionally found in patients with microcephaly. Various non-coding RNAs (ncRNAs), such as microRNAs (miRNAs), SINEUPs, telomerase RNA component (TERC), and promoter-associated lncRNAs (pancRNAs) are now being characterized. These ncRNAs regulate gene expression, enzyme activity, telomere length, and chromatin structure through RNA binding proteins (RBPs)-RNA interaction. Elucidating the potential roles of ncRNA-protein coordination in microcephaly pathogenesis might contribute to its prevention or recovery. Here, we introduce several syndromes whose clinical features include microcephaly. In particular, we focus on syndromes for which ncRNAs or genes that interact with ncRNAs may play roles. We discuss the possibility that the huge ncRNA field will provide possible new therapeutic approaches for microcephaly and also reveal clues about the factors enabling the evolutionary acquisition of the human-specific "large brain."
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Fujimoto M, Nakamura Y, Iwaki T, Sato E, Ieda D, Hattori A, Shiraki A, Mizuno S, Saitoh S. Angelman syndrome with mosaic paternal uniparental disomy suggestive of mitotic nondisjunction. J Hum Genet 2023; 68:87-90. [PMID: 36224263 DOI: 10.1038/s10038-022-01088-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Revised: 09/15/2022] [Accepted: 09/27/2022] [Indexed: 01/27/2023]
Abstract
Angelman syndrome (AS) is caused by the functional absence of the maternal ubiquitin-protein ligase E3A (UBE3A) gene. Approximately 5% of AS is caused by paternal uniparental disomy of chromosome 15 (UPD(15)pat), most of which is considered to result from monosomy rescue. However, little attention has focused on how UPD(15)pat occurs. We suggest the mitotic nondisjunction mechanism as a cause of UPD(15)pat in a six-year-old patient presenting with distinctive characteristics in line with AS. DNA methylation screening of 15q11-q13 showed a paternal band and a faint maternal band, suggestive of mosaic status. By trio-based microsatellite analysis, we confirmed a large proportion of UPD(15)pat cells and a small proportion of cells of biparental origin. Single nucleotide polymorphism (SNP) microarray revealed isodisomy of the entire chromosome 15. These results suggest that the UPD(15)pat of the patient resulted from mitotic nondisjunction, which may also be the cause of other cases of AS with UPD(15)pat.
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Affiliation(s)
- Masanori Fujimoto
- Department of Pediatrics and Neonatology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
| | - Yuji Nakamura
- Department of Pediatrics and Neonatology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
| | - Toshihiko Iwaki
- Department of Pediatrics and Neonatology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
| | - Emi Sato
- Department of Pediatrics and Neonatology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
| | - Daisuke Ieda
- Department of Pediatrics and Neonatology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
| | - Ayako Hattori
- Department of Pediatrics and Neonatology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
| | - Anna Shiraki
- Department of Child Neurology, Toyota Municipal Child Development Center Nozomi Clinic, Toyota, Japan.,Department of Pediatrics, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Seiji Mizuno
- Department of Pediatrics, Central Hospital, Aichi Developmental Disability Center, Aichi, Japan
| | - Shinji Saitoh
- Department of Pediatrics and Neonatology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan.
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Hnoonual A, Kor-Anantakul P, Charalsawadi C, Worachotekamjorn J, Limprasert P. Case Report: An Atypical Angelman Syndrome Case With Obesity and Fulfilled Autism Spectrum Disorder Identified by Microarray. Front Genet 2021; 12:755605. [PMID: 34630535 PMCID: PMC8494305 DOI: 10.3389/fgene.2021.755605] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Accepted: 09/07/2021] [Indexed: 11/26/2022] Open
Abstract
Autism spectrum disorder (ASD) is a group of neurodevelopmental disorders which are etiologically heterogeneous. Chromosomal microarray is now recommended as the first-tier clinical diagnostic test for ASD. We performed chromosomal microarray in 16 Thai patients with ASD using an Illumina HumanCytoSNP-12 v2.1 array and found one case with uniparental disomy (UPD) of chromosome 15. Methylation-specific PCR showed abnormal methylation of the maternal SNRPN allele. Haplotype analysis revealed that the patient had received both chromosomes 15 from his father. These results were consistent with Angelman syndrome. However, his clinical features had no clinical significance for classic Angelman syndrome. He had first presented at the pediatric clinic with no speech, poor social interaction skills and repetitive behaviors consistent with ASD based on the DSM-IV criteria at 2 years of age and later confirmed by ADOS at 5 years of age. He was strikingly overweight but had no dysmorphic facies, seizures nor ataxia and was diagnosed as non-syndromic ASD, a diagnosis which was believed until at 10 years of age, his DNA was included for analysis in this current cohort study. Our findings suggest that ASD patients with unknown etiology should be considered for methylation-specific PCR testing for Angelman syndrome where chromosomal microarray is not available. In the study, we also review the clinical features of Angelman syndrome caused by UPD and the frequency of ASD in individuals with Angelman syndrome.
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Affiliation(s)
- Areerat Hnoonual
- Department of Pathology, Faculty of Medicine, Prince of Songkla University, Songkhla, Thailand
| | - Phawin Kor-Anantakul
- Center of Excellence for Medical Genomics, Medical Genomics Cluster, Department of Pediatrics, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand.,Excellence Center for Genomics and Precision Medicine, King Chulalongkorn Memorial Hospital, Thai Red Cross Society, Bangkok, Thailand
| | - Chariyawan Charalsawadi
- Department of Pathology, Faculty of Medicine, Prince of Songkla University, Songkhla, Thailand
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Takahashi Y, Hosoki K, Matsushita M, Funatsuka M, Saito K, Kanazawa H, Goto YI, Saitoh S. A loss-of-function mutation in the SLC9A6 gene causes X-linked mental retardation resembling Angelman syndrome. Am J Med Genet B Neuropsychiatr Genet 2011; 156B:799-807. [PMID: 21812100 DOI: 10.1002/ajmg.b.31221] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/29/2010] [Accepted: 07/06/2011] [Indexed: 02/06/2023]
Abstract
SLC9A6 mutations have been reported in families in whom X-linked mental retardation (XMR) mimics Angelman syndrome (AS). However, the relative importance of SLC9A6 mutations in patients with an AS-like phenotype or XMR has not been fully investigated. Here, the involvement of SLC9A6 mutations in 22 males initially suspected to have AS but found on genetic testing not to have AS (AS-like cohort), and 104 male patients with XMR (XMR cohort), was investigated. A novel SLC9A6 mutation (c.441delG, p.S147fs) was identified in one patient in the AS-like cohort, but no mutation was identified in XMR cohort, suggesting mutations in SLC9A6 are not a major cause of the AS-like phenotype or XMR. The patient with the SLC9A6 mutation showed the typical AS phenotype, further demonstrating the similarity between patients with AS and those with SLC9A6 mutations. To clarify the effect of the SLC9A6 mutation, we performed RT-PCR and Western blot analysis on lymphoblastoid cells from the patient. Expression of the mutated transcript was significantly reduced, but was restored by cycloheximide treatment, indicating the presence of nonsense mediated mRNA decay. Western blot analysis demonstrated absence of the normal NHE6 protein encoded for by SLC9A6. Taken together, these findings indicate a loss-of-function mutation in SLC9A6 caused the phenotype in our patient.
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Affiliation(s)
- Yumi Takahashi
- Department of Pediatrics, Hokkaido University Graduate School of Medicine, Sapporo, Japan
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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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Abstract
Angelman syndrome is characterized by severe developmental delay, speech impairment, gait ataxia and/or tremulousness of the limbs, and a unique behavioral phenotype that includes happy demeanor and excessive laughter. Microcephaly and seizures are common. Developmental delays are first noted at 3 to 6 months age, but the unique clinical features of the syndrome do not become manifest until after age 1 year. Management includes treatment of gastrointestinal symptoms, use of antiepileptic drugs for seizures, and provision of physical, occupational, and speech therapy with an emphasis on nonverbal methods of communication. The diagnosis rests on a combination of clinical criteria and molecular and/or cytogenetic testing. Analysis of parent-specific DNA methylation imprints in the 15q11.2-q13 chromosome region detects approximately 78% of individuals with lack of maternal contribution. Less than 1% of individuals have a visible chromosome rearrangement. UBE3A sequence analysis detects mutations in an additional 11% of individuals. The remaining 10% of individuals with classic phenotypic features of Angelman syndrome have a presently unidentified genetic mechanism and thus are not amenable to diagnostic testing. The risk to sibs of a proband depends on the genetic mechanism of the loss of the maternally contributed Angelman syndrome/Prader-Willi syndrome region: typically <1% for probands with a deletion or uniparental disomy; as high as 50% for probands with an imprinting defect or a mutation of UBE3A. Members of the mother's extended family are also at increased risk when an imprinting defect or a UBE3A mutation is present. Chromosome rearrangements may be inherited or de novo. Prenatal testing is possible for certain genetic mechanisms.
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Abstract
Human imprinting disorders can provide critical insights into the role of imprinted genes in human development and health, and the molecular mechanisms that regulate genomic imprinting. To illustrate these concepts we review the clinical and molecular features of several human imprinting syndromes including Beckwith–Wiedemann syndrome, Silver–Russell syndrome, Angelman syndrome, Prader–Willi syndrome, pseudohypoparathyroidism, transient neonatal diabetes, familial complete hydatidiform moles and chromosome 14q32 imprinting domain disorders.
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Affiliation(s)
- Derek HK Lim
- Birmingham Women’s Hospital, Birmingham UK
- Department of Medical & Molecular Genetics, School of Clinical and Experimental Medicine, University of Birmingham College of Medical and Dental Sciences, Edgbaston, Birmingham, B15 2TT, UK
| | - Eamonn R Maher
- Birmingham Women’s Hospital, Birmingham UK
- Department of Medical & Molecular Genetics, School of Clinical and Experimental Medicine, University of Birmingham College of Medical and Dental Sciences, Edgbaston, Birmingham, B15 2TT, UK
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Asahina N, Shiga T, Egawa K, Shiraishi H, Kohsaka S, Saitoh S. [(11)C]flumazenil positron emission tomography analyses of brain gamma-aminobutyric acid type A receptors in Angelman syndrome. J Pediatr 2008; 152:546-9, 549.e1-3. [PMID: 18346513 DOI: 10.1016/j.jpeds.2007.08.038] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/25/2007] [Revised: 08/03/2007] [Accepted: 08/23/2007] [Indexed: 11/19/2022]
Abstract
OBJECTIVE To evaluate the role of the gamma-aminobutyric acid type A (GABA(A)) receptor in Angelman syndrome (AS). STUDY DESIGN We performed [(11)C]flumazenil positron emission tomography (PET) and examined GABA(A) receptor expression in 7 patients with AS of various genotypes (5 with the deletion, 1 with an imprinting defect [ID], and 1 with a UBE3A mutation) and 4 normal control healthy volunteers. RESULTS Relative to the control subjects, the [(11)C]flumazenil binding potentials (BPs) were significantly higher in the cerebral cortex and cerebellum in the 5 patients with the deletion and in the 1 patient with a UBE3A mutation, and were less frequently or barely increased in adult patients with the deletion and in the patient with IDs. CONCLUSIONS Total GABA(A) receptor expression was increased in patients with AS with various genotypes. We suggest that a developmental dysregulation of the GABA(A) receptor subunits occurs in patients with AS.
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Affiliation(s)
- Naoko Asahina
- Department of Pediatrics, Hokkaido University Graduate School of Medicine, Sapporo, Japan
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