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Jalaiei A, Asadi MR, Daneshmandpour Y, Rezazadeh M, Ghafouri-Fard S. Clinical, molecular, physiologic, and therapeutic feature of patients with CHRNA4 and CHRNB2 deficiency: A systematic review. J Neurochem 2024. [PMID: 39193833 DOI: 10.1111/jnc.16200] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2024] [Revised: 07/03/2024] [Accepted: 07/26/2024] [Indexed: 08/29/2024]
Abstract
The α4β2 nAChRs are crucial ion channels that control neurotransmitter release and play a role in various physiologic and pathologic processes. CHRNA4 encodes the α4-nAChRs, while CHRNB2 encodes the β2-nAChRs. Recent studies have found different variants of α4β2-nAChRs in individuals with conditions such as AD, ADHD, ALS, PD, and brain abnormalities. We conducted a scoping review following a six-stage methodology structure and adhering to PRISMA guidelines. We systematically reviewed articles using relevant keywords up to October 2, 2023. In this summary, we cover the clinical symptoms reported, the genes and protein structure of CHRNA4 and CHRNB2, mutations in these genes, inheritance patterns, the functional impact of mutations and polymorphisms in CHRNA4 and CHRNB2, and the epidemiology of these diseases. Recent research indicates that nAChRs may play a significant role in neurodegenerative disorders, possibly impacting neuronal function through yet undiscovered regulatory pathways. Studying how nAChRs interact with disease-related aggregates in neurodegenerative conditions may lead to new treatment options for these disorders.
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Affiliation(s)
- Abbas Jalaiei
- Department of Medical Genetics, Faculty of Medicine, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Mohammad Reza Asadi
- Department of Medical Genetics, Faculty of Medicine, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Yousef Daneshmandpour
- Department of Medical Genetics, Faculty of Medicine, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Maryam Rezazadeh
- Department of Medical Genetics, Faculty of Medicine, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Soudeh Ghafouri-Fard
- Department of Medical Genetics, Faculty of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
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Zhuang J, Zhang N, Wang J, Jiang Y, Zhang H, Chen C. Initial clinical and molecular investigation of 20q13.33 microdeletion with 17q25.3/14q32.31q32.33 microduplication in Chinese pediatric patients. Mol Genet Genomic Med 2024; 12:e2429. [PMID: 38553934 PMCID: PMC10980884 DOI: 10.1002/mgg3.2429] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2023] [Revised: 03/01/2024] [Accepted: 03/19/2024] [Indexed: 04/02/2024] Open
Abstract
BACKGROUND Limited research has been conducted regarding the elucidation of genotype-phenotype correlations within the 20q13.33 region. The genotype-phenotype association of 20q13.33 microdeletion remains inadequately understood. In the present study, two novel cases of 20q13.33 microdeletion were introduced, with the objective of enhancing understanding of the genotype-phenotype relationship. METHODS Two unrelated patients with various abnormal clinical phenotypes from Fujian province Southeast China were enrolled in the present study. Karyotype analysis and chromosomal microarray analysis (CMA) were performed to investigate chromosomal abnormalities and copy number variants. RESULTS The results of high-resolution G-banding karyotype analysis elicited a 46,XY,der(20)add(20)(q13.3) in Patient 1. This patient exhibited various clinical manifestations, such as global developmental delay, intellectual disability, seizures, and other congenital diseases. Subsequently, a 1.0-Mb deletion was identified in the 20q13.33 region alongside a 5.2-Mb duplication in the 14q32.31q32.33 region. In Patient 2, CMA results revealed a 1.8-Mb deletion in the 20q13.33 region with a 4.8-Mb duplication of 17q25.3. The patient exhibited additional abnormal clinical features, including micropenis, congenital heart disease, and a distinctive crying pattern characterized by a crooked mouth. CONCLUSION In the present study, for the first time, an investigation was conducted into two novel cases of 20q13.33 microdeletion with microduplications in the 17q25.3 and 14q32.31q32.33 regions in the Chinese population. The presence of micropenis may be attributed to the 20q13.33 microdeletion, potentially expanding the phenotypic spectrum associated with this deletion.
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Affiliation(s)
- Jianlong Zhuang
- Prenatal Diagnosis Center, Quanzhou Women's and Children's HospitalQuanzhouChina
| | - Na Zhang
- Prenatal Diagnosis Center, Quanzhou Women's and Children's HospitalQuanzhouChina
| | - Junyu Wang
- Prenatal Diagnosis Center, Quanzhou Women's and Children's HospitalQuanzhouChina
| | - Yuying Jiang
- Prenatal Diagnosis Center, Quanzhou Women's and Children's HospitalQuanzhouChina
| | - Hegan Zhang
- Department of GynecologyQuanzhou Women's and Children's HospitalQuanzhouChina
| | - Chunnuan Chen
- Department of NeurologyThe Second Affiliated Hospital of Fujian Medical UniversityQuanzhouChina
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Ürel-Demir G, Akgün-Doğan Ö, Oğuz S, Güleray-Lafcı N, Şimşek-Kiper PÖ, Eda Utine G, Alikaşifoğlu M, Boduroğlu K. Further Phenotypic Delineation of Partial Trisomy 17q and Partial Monosomy 20q due to Rare t(17;20). Mol Syndromol 2020; 11:38-42. [PMID: 32256300 PMCID: PMC7109379 DOI: 10.1159/000505141] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/22/2019] [Indexed: 11/19/2022] Open
Abstract
Copy number variations in subtelomeric regions of chromosomes 17 and 20 are associated with intellectual disability and various systemic manifestations. Microarray analysis allows identification of submicroscopic chromosomal abnormalities and is applicable to elucidate the etiology of cognitive impairment in approximately one-fifth of the cases. In the present study, we report on 3 male children from 2 sisters, who suffered from intellectual disability, facial dysmorphism, and epilepsy. Despite the initial suggestion of an X-linked inheritance, the condition was associated with 17q25.3 duplication and concomitant 20q13.33 deletion, as detected by microarray analysis. Coexistence of a deletion and a duplication suggests unbalanced segregation of a parental balanced translocation. Further investigations revealed maternal balanced translocations, which resulted in copy number aberrations in the children following unbalanced segregations. The work-up underlined the importance of genomic screening using microarrays as the first-tier diagnostic tool in intellectual disability, despite an apparent X-linked segregation in the pedigree.
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Affiliation(s)
- Gizem Ürel-Demir
- Department of Pediatric Genetics, Faculty of Medicine, Hacettepe University Ankara, Turkey
| | - Özlem Akgün-Doğan
- Department of Pediatric Genetics, Faculty of Medicine, Hacettepe University Ankara, Turkey
| | - Sümeyra Oğuz
- Department of Medical Genetics, Faculty of Medicine, Hacettepe University, Ankara, Turkey
| | - Naz Güleray-Lafcı
- Department of Medical Genetics, Faculty of Medicine, Hacettepe University, Ankara, Turkey
| | | | - Gülen Eda Utine
- Department of Pediatric Genetics, Faculty of Medicine, Hacettepe University Ankara, Turkey
| | - Mehmet Alikaşifoğlu
- Department of Medical Genetics, Faculty of Medicine, Hacettepe University, Ankara, Turkey
| | - Koray Boduroğlu
- Department of Pediatric Genetics, Faculty of Medicine, Hacettepe University Ankara, Turkey
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Corrêa T, Venâncio AC, Galera MF, Riegel M. Candidate Genes Associated with Delayed Neuropsychomotor Development and Seizures in a Patient with Ring Chromosome 20. Case Rep Genet 2020; 2020:5957415. [PMID: 32082653 PMCID: PMC6995492 DOI: 10.1155/2020/5957415] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2019] [Accepted: 12/17/2019] [Indexed: 11/25/2022] Open
Abstract
Ring chromosome 20 (r20) is characterized by intellectual impairment, behavioral disorders, and refractory epilepsy. We report a patient presenting nonmosaic ring chromosome 20 followed by duplication and deletion in 20q13.33 with seizures, delayed neuropsychomotor development and language, mild hypotonia, low weight gain, and cognitive deficit. Chromosomal microarray analysis (CMA) enabled us to restrict a chromosomal segment and thus integrate clinical and molecular data with systems biology. With this approach, we were able to identify candidate genes that may help to explain the consequences of deletions in 20q13.33. In our analysis, we observed five hubs (ARFGAP1, HELZ2, COL9A3, PTK6, and EEF1A2), seven bottlenecks (CHRNA4, ARFRP1, GID8, COL9A3, PTK6, ZBTB46, and SRMS), and two H-B nodes (PTK6 and COL9A3). The candidate genes may play an important role in the developmental delay and seizures observed in r20 patients. Gene ontology included microtubule-based movement, nucleosome assembly, DNA repair, and cholinergic synaptic transmission. Defects in these bioprocesses are associated with the development of neurological diseases, intellectual disability, neuropathies, and seizures. Therefore, in this study, we can explore molecular cytogenetic data, identify proteins through network analysis of protein-protein interactions, and identify new candidate genes associated with the main clinical findings in patients with 20q13.33 deletions.
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Affiliation(s)
- Thiago Corrêa
- Genetics Department, Post-Graduate Program in Genetics and Molecular Biology, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS, Brazil
| | - Amanda Cristina Venâncio
- Post-Graduate Program in Health Sciences, Universidade Federal do Mato Grosso (UFMT), Cuiabá, MT, Brazil
| | - Marcial Francis Galera
- Department of Pediatrics, Universidade Federal do Mato Grosso (UFMT), Cuiabá, MT, Brazil
| | - Mariluce Riegel
- Genetics Department, Post-Graduate Program in Genetics and Molecular Biology, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS, Brazil
- Medical Genetics Service, Hospital de Clínicas, Porto Alegre, RS, Brazil
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Peycheva V, Ivanova N, Kamenarova K, Tsekova I, Aleksandrova I, Bozhinova V, Bozhidarova M, Litvinenko I, Hristova D, Mitev V, Kaneva R, Jordanova A. Impact of KCNQ2 mutations in Bulgarian patients with electroclinical syndromes with onset in the first year of life. BIOTECHNOL BIOTEC EQ 2017. [DOI: 10.1080/13102818.2016.1259017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
Affiliation(s)
- Valentina Peycheva
- Department of Medical Chemistry and Biochemistry, Molecular Medicine Center, Medical University of Sofia, Sofia, Bulgaria
| | - Neviana Ivanova
- Department of Medical Chemistry and Biochemistry, Molecular Medicine Center, Medical University of Sofia, Sofia, Bulgaria
| | - Kunka Kamenarova
- Department of Medical Chemistry and Biochemistry, Molecular Medicine Center, Medical University of Sofia, Sofia, Bulgaria
| | - Irina Tsekova
- Department of Medical Chemistry and Biochemistry, Molecular Medicine Center, Medical University of Sofia, Sofia, Bulgaria
| | - Iliyana Aleksandrova
- Department of Neurology, Clinic of Child Neurology, University Hospital of Neurology and Psychiatry “St' Naum”, Medical University of Sofia, Sofia, Bulgaria
| | - Veneta Bozhinova
- Department of Neurology, Clinic of Child Neurology, University Hospital of Neurology and Psychiatry “St' Naum”, Medical University of Sofia, Sofia, Bulgaria
| | - Maria Bozhidarova
- Department of Pediatric Neurology, University Pediatrics Hospital, Medical University of Sofia, Sofia, Bulgaria
| | - Ivan Litvinenko
- Department of Pediatric Neurology, University Pediatrics Hospital, Medical University of Sofia, Sofia, Bulgaria
| | - Dimitrina Hristova
- Children Neurology Unit, Pediatrics Clinic, Tokuda Hospital, Sofia, Bulgaria
| | - Vanyo Mitev
- Department of Medical Chemistry and Biochemistry, Molecular Medicine Center, Medical University of Sofia, Sofia, Bulgaria
| | - Radka Kaneva
- Department of Medical Chemistry and Biochemistry, Molecular Medicine Center, Medical University of Sofia, Sofia, Bulgaria
| | - Albena Jordanova
- Department of Medical Chemistry and Biochemistry, Molecular Medicine Center, Medical University of Sofia, Sofia, Bulgaria
- VIB Department of Molecular Genetics, Molecular Neurogenomics Group, University of Antwerp, Antwerp, Belgium
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Dido mutations trigger perinatal death and generate brain abnormalities and behavioral alterations in surviving adult mice. Proc Natl Acad Sci U S A 2015; 112:4803-8. [PMID: 25825751 DOI: 10.1073/pnas.1419300112] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Nearly all vertebrate cells have a single cilium protruding from their surface. This threadlike organelle, once considered vestigial, is now seen as a pivotal element for detection of extracellular signals that trigger crucial morphogenetic pathways. We recently proposed a role for Dido3, the main product of the death inducer-obliterator (dido) gene, in histone deacetylase 6 delivery to the primary cilium [Sánchez de Diego A, et al. (2014) Nat Commun 5:3500]. Here we used mice that express truncated forms of Dido proteins to determine the link with cilium-associated disorders. We describe dido mutant mice with high incidence of perinatal lethality and distinct neurodevelopmental, morphogenetic, and metabolic alterations. The anatomical abnormalities were related to brain and orofacial development, consistent with the known roles of primary cilia in brain patterning, hydrocephalus incidence, and cleft palate. Mutant mice that reached adulthood showed reduced life expectancy, brain malformations including hippocampus hypoplasia and agenesis of corpus callosum, as well as neuromuscular and behavioral alterations. These mice can be considered a model for the study of ciliopathies and provide information for assessing diagnosis and therapy of genetic disorders linked to the deregulation of primary cilia.
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A novel de novo 20q13.32-q13.33 deletion in a 2-year-old child with poor growth, feeding difficulties and low bone mass. J Hum Genet 2015; 60:313-7. [PMID: 25761574 DOI: 10.1038/jhg.2015.22] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2015] [Revised: 01/30/2015] [Accepted: 02/04/2015] [Indexed: 11/08/2022]
Abstract
Interstitial deletions of the long arm of chromosome 20 are rarely reported in the literature. We report a 2-year-old child with a 2.6 Mb deletion of 20q13.32-q13.33, detected by microarray-based comparative genomic hybridization, who presented with poor growth, feeding difficulties, abnormal subcutaneous fat distribution with the lack of adipose tissue on clinical examination, facial dysmorphism and low bone mass. This report adds to rare publications describing constitutional aberrations of chromosome 20q, and adds further evidence to the fact that deletion of the GNAS complex may not always be associated with an Albright's hereditary osteodystrophy phenotype as described previously.
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Allen NM, Mannion M, Conroy J, Lynch SA, Shahwan A, Lynch B, King MD. The variable phenotypes of KCNQ-related epilepsy. Epilepsia 2014; 55:e99-105. [DOI: 10.1111/epi.12715] [Citation(s) in RCA: 90] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/02/2014] [Indexed: 11/28/2022]
Affiliation(s)
- Nicholas M. Allen
- Department of Paediatric Neurology & Clinical Neurophysiology; Children's University Hospital; Dublin Ireland
| | - Maria Mannion
- Department of Paediatric Neurology & Clinical Neurophysiology; Children's University Hospital; Dublin Ireland
| | - Judith Conroy
- Academic Centre on Rare Diseases; School of Medicine and Medical Science; University College; Dublin Ireland
| | - Sally A. Lynch
- Academic Centre on Rare Diseases; School of Medicine and Medical Science; University College; Dublin Ireland
- Department of Clinical Genetics; Children's University Hospital; Temple St. Dublin Ireland
| | - Amre Shahwan
- Department of Paediatric Neurology & Clinical Neurophysiology; Children's University Hospital; Dublin Ireland
| | - Bryan Lynch
- Department of Paediatric Neurology & Clinical Neurophysiology; Children's University Hospital; Dublin Ireland
| | - Mary D. King
- Department of Paediatric Neurology & Clinical Neurophysiology; Children's University Hospital; Dublin Ireland
- Academic Centre on Rare Diseases; School of Medicine and Medical Science; University College; Dublin Ireland
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Mosca-Boidron AL, Valduga M, Thauvin-Robinet C, Lagarde N, Marle N, Henry C, Pinoit JM, Huet F, Béri-Deixheimer M, Ragon C, Gueneau L, Payet M, Callier P, Mugneret F, Jonveaux P, Faivre L. Additional evidence to support the role of the 20q13.33 region in susceptibility to autism. Am J Med Genet A 2013; 161A:1505-7. [PMID: 23613186 DOI: 10.1002/ajmg.a.35878] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2012] [Accepted: 12/19/2012] [Indexed: 11/10/2022]
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10
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Mefford HC, Cook J, Gospe SM. Epilepsy due to 20q13.33 subtelomere deletion masquerading as pyridoxine-dependent epilepsy. Am J Med Genet A 2012; 158A:3190-5. [DOI: 10.1002/ajmg.a.35633] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2012] [Accepted: 07/30/2012] [Indexed: 02/03/2023]
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12
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Traylor RN, Bruno DL, Burgess T, Wildin R, Spencer A, Ganesamoorthy D, Amor DJ, Hunter M, Caplan M, Rosenfeld JA, Theisen A, Torchia BS, Shaffer LG, Ballif BC, Slater HR. A genotype-first approach for the molecular and clinical characterization of uncommon de novo microdeletion of 20q13.33. PLoS One 2010; 5:e12462. [PMID: 20805988 PMCID: PMC2929201 DOI: 10.1371/journal.pone.0012462] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2010] [Accepted: 06/16/2010] [Indexed: 11/21/2022] Open
Abstract
Background Subtelomeric deletions of the long arm of chromosome 20 are rare, with only 11 described in the literature. Clinical features of individuals with these microdeletions include severe limb malformations, skeletal abnormalities, growth retardation, developmental and speech delay, mental retardation, seizures and mild, non-specific dysmorphic features. Methodology/Principal Findings We characterized microdeletions at 20q13.33 in six individuals referred for genetic evaluation of developmental delay, mental retardation, and/or congenital anomalies. A comparison to previously reported cases of 20q13.33 microdeletion shows phenotypic overlap, with clinical features that include mental retardation, developmental delay, speech and language deficits, seizures, and behavior problems such as autistic spectrum disorder. There does not appear to be a clinically recognizable constellation of dysmorphic features among individuals with subtelomeric 20q microdeletions. Conclusions/Significance Based on genotype-phenotype correlation among individuals in this and previous studies, we discuss several possible candidate genes for specific clinical features, including ARFGAP1, CHRNA4 and KCNQ2 and neurodevelopmental deficits. Deletion of this region may play an important role in cognitive development.
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Affiliation(s)
- Ryan N Traylor
- Signature Genomic Laboratories, Spokane, Washington, United States of America
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Wang BT, Hemmat M, Jayakar P, Boyar F, Chan P, El Naggar M, Anguiano A. Paternal mosaic inv(20) resulting in a recombinant chromosome 20 in two siblings. Pediatr Int 2010; 52:492-5. [PMID: 20723126 DOI: 10.1111/j.1442-200x.2010.03041.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Bao-Tyan Wang
- Cytogenetics Department, Quest Diagnostics Nichols Institute, San Juan Capistrano, California, USA
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Descipio C, Morrissette JD, Conlin LK, Clark D, Kaur M, Coplan J, Riethman H, Spinner NB, Krantz ID. Two siblings with alternate unbalanced recombinants derived from a large cryptic maternal pericentric inversion of chromosome 20. Am J Med Genet A 2010; 152A:373-82. [PMID: 20101690 DOI: 10.1002/ajmg.a.33219] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Two brothers, with dissimilar clinical features, were each found to have different abnormalities of chromosome 20 by subtelomere fluorescence in situ hybridization (FISH). The proband had deletion of 20p subtelomere and duplication of 20q subtelomere, while his brother was found to have a duplication of 20p subtelomere and deletion of 20q subtelomere. Parental cytogenetic studies were initially thought to be normal, both by G-banding and by subtelomere FISH analysis. Since chromosome 20 is a metacentric chromosome and an inversion was suspected, we used anchored FISH to assist in identifying a possible inversion. This approach employed concomitant hybridization of a FISH probe to the short (p) arm of chromosome 20 with the 20q subtelomere probe. We identified a cytogenetically non-visible, mosaic pericentric inversion of one of the maternal chromosome 20 homologs, providing a mechanistic explanation for the chromosomal abnormalities present in these brothers. Array comparative genomic hybridization (CGH) with both a custom-made BAC and cosmid-based subtelomere specific array (TEL array) and a commercially available SNP-based array confirmed and further characterized these rearrangements, identifying this as the largest pericentric inversion of chromosome 20 described to date. TEL array data indicate that the 20p breakpoint is defined by BAC RP11-978M13, approximately 900 kb from the pter; SNP array data reveal this breakpoint to occur within BAC RP11-978M13. The 20q breakpoint is defined by BAC RP11-93B14, approximately 1.7 Mb from the qter, by TEL array; SNP array data refine this breakpoint to within a gap between BACs on the TEL array (i.e., between RP11-93B14 and proximal BAC RP11-765G16).
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Affiliation(s)
- Cheryl Descipio
- Division of Human Genetics, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania 19104, USA
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Schluth-Bolard C, Till M, Edery P, Sanlaville D. [New chromosomal syndromes]. ACTA ACUST UNITED AC 2008; 56:380-7. [PMID: 18467039 DOI: 10.1016/j.patbio.2008.03.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2008] [Accepted: 03/14/2008] [Indexed: 10/22/2022]
Abstract
Mental retardation occurs in 2-3% of the general population either in isolation or in combination with facial dysmorphism and/or malformations. Chromosomal abnormalities are a most common etiology. Karyotype displays chromosome aberrations in about 10% of patients but it has a limited resolution (5 Mb). Recently, the development of new molecular cytogenetic tools, especially array CGH, allowed to detect smaller abnormalities and increased the diagnosis capability of 15-20%. Among these newly detected rearrangements, some of them are recurrent and define new recognized syndromes. We will first briefly explain the non-allelic homologous recombination (NAHR) mechanism that underlines the origin of recurrent microdeletions and microduplications. Then we will describe eight new syndromes, four microdeletions (del 17q21.31, del 3q29, del 15q24, del 2q32.3q33) and four microduplications (dup 22q11.2, dup 7q11.23, dup 17p11.2, duplication of MECP2). A better knowledge of these new recurrent chromosomal syndromes will allow to improve care for patients, to develop targeted chromosomal diagnosis and to identify genes involved in neurocognitive functions.
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Affiliation(s)
- C Schluth-Bolard
- Service de cytogénétique constitutionnelle, hospices civils de Lyon, centre de biologie et de pathologie Est, 59, boulevard Pinel, 69677 Bron, cedex, France
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