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Tamura T, Shimojima Yamamoto K, Imaizumi T, Yamamoto H, Miyamoto Y, Yagasaki H, Morioka I, Kanno H, Yamamoto T. Breakpoint analysis for cytogenetically balanced translocation revealed unexpected complex structural abnormalities and suggested the position effect for MEF2C. Am J Med Genet A 2023; 191:1632-1638. [PMID: 36916329 DOI: 10.1002/ajmg.a.63182] [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: 11/08/2022] [Revised: 01/27/2023] [Accepted: 03/02/2023] [Indexed: 03/15/2023]
Abstract
Many disease-causing genes have been identified by determining the breakpoints of balanced chromosomal translocations. Recent progress in genomic analysis has accelerated the analysis of chromosomal translocation-breakpoints at the nucleotide level. Using a long-read whole-genome sequence, we analyzed the breakpoints of the cytogenetically balanced chromosomal translocation t(5;15)(q21;26.3), which was confirmed to be of de novo origin, in a patient with a neurodevelopmental disorder. The results showed complex rearrangements with seven fragments consisting of five breakpoint-junctions (BJs). Four of the five BJs showed microhomologies of 1-3-bp, and only one BJ displayed a signature of blunt-end ligation, indicating chromothripsis as the underlying mechanism. Although the BJs did not disrupt any disease-causing gene, the clinical features of the patient were compatible with MEF2C haploinsufficiency syndrome. Complex rearrangements were located approximately 2.5-Mb downstream of MEF2C. Therefore, position effects were considered the mechanism of the occurrence of MEF2C haploinsufficiency syndrome.
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Affiliation(s)
- Takeaki Tamura
- Department of Pediatrics and Child Health, Nihon University School of Medicine, Tokyo, Japan.,Division of Gene Medicine, Graduate School of Medical Science, Tokyo Women's Medical University, Tokyo, Japan.,Department of Transfusion Medicine and Cell Processing, Tokyo Women's Medical University, Tokyo, Japan
| | - Keiko Shimojima Yamamoto
- Department of Transfusion Medicine and Cell Processing, Tokyo Women's Medical University, Tokyo, Japan.,Institute of Medical Genetics, Tokyo Women's Medical University, Tokyo, Japan
| | - Taichi Imaizumi
- Department of Pediatrics, St. Marianna University School of Medicine, Kawasaki, Japan
| | - Hisako Yamamoto
- Department of Pediatrics, St. Marianna University School of Medicine, Kawasaki, Japan
| | - Yusaku Miyamoto
- Department of Pediatrics, St. Marianna University School of Medicine, Kawasaki, Japan
| | - Hiroshi Yagasaki
- Department of Pediatrics and Child Health, Nihon University School of Medicine, Tokyo, Japan
| | - Ichiro Morioka
- Department of Pediatrics and Child Health, Nihon University School of Medicine, Tokyo, Japan
| | - Hitoshi Kanno
- Department of Transfusion Medicine and Cell Processing, Tokyo Women's Medical University, Tokyo, Japan.,Institute of Medical Genetics, Tokyo Women's Medical University, Tokyo, Japan
| | - Toshiyuki Yamamoto
- Division of Gene Medicine, Graduate School of Medical Science, Tokyo Women's Medical University, Tokyo, Japan.,Institute of Medical Genetics, Tokyo Women's Medical University, Tokyo, Japan
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Vitrac A, Leblond CS, Rolland T, Cliquet F, Mathieu A, Maruani A, Delorme R, Schön M, Grabrucker AM, van Ravenswaaij-Arts C, Phelan K, Tabet AC, Bourgeron T. Dissecting the 22q13 region to explore the genetic and phenotypic diversity of patients with Phelan-McDermid syndrome. Eur J Med Genet 2023; 66:104732. [PMID: 36822569 DOI: 10.1016/j.ejmg.2023.104732] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2022] [Revised: 02/14/2023] [Accepted: 02/19/2023] [Indexed: 02/25/2023]
Abstract
SHANK3-related Phelan-McDermid syndrome (PMS) is caused by a loss of the distal part of chromosome 22, including SHANK3, or by a pathological SHANK3 variant. There is an important genetic and phenotypic diversity among patients who can present with developmental delay, language impairments, autism, epilepsy, and other symptoms. SHANK3, encoding a synaptic scaffolding protein, is deleted in the majority of patients with PMS and is considered a major gene involved in the neurological impairments of the patients. However, differences in deletion size can influence clinical features, and in some rare cases, deletions at the 22q13 locus in individuals with SHANK3-unrelated PMS do not encompass SHANK3. These individuals with SHANK3-unrelated PMS still display a PMS-like phenotype. This suggests the participation of other 22q13 genes in the pathogenesis of PMS. Here, we review the biological function and potential implication in PMS symptoms of 110 genes located in the 22q13 region, focusing on 35 genes with evidence for association with neurodevelopmental disorders, including 13 genes for epilepsy and 11 genes for microcephaly and/or macrocephaly. Our review is restricted to the 22q13 region, but future large-scale studies using whole genome sequencing and deep-phenotyping are warranted to develop predictive models of clinical trajectories and to target specific medical and educational care for each individual with PMS.
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Affiliation(s)
- Aline Vitrac
- Génétique Humaine et Fonctions Cognitives, Institut Pasteur, UMR3571 CNRS, Université de Paris Cité, IUF, 75015, Paris, France.
| | - Claire S Leblond
- Génétique Humaine et Fonctions Cognitives, Institut Pasteur, UMR3571 CNRS, Université de Paris Cité, IUF, 75015, Paris, France
| | - Thomas Rolland
- Génétique Humaine et Fonctions Cognitives, Institut Pasteur, UMR3571 CNRS, Université de Paris Cité, IUF, 75015, Paris, France
| | - Freddy Cliquet
- Génétique Humaine et Fonctions Cognitives, Institut Pasteur, UMR3571 CNRS, Université de Paris Cité, IUF, 75015, Paris, France
| | - Alexandre Mathieu
- Génétique Humaine et Fonctions Cognitives, Institut Pasteur, UMR3571 CNRS, Université de Paris Cité, IUF, 75015, Paris, France
| | - Anna Maruani
- Department of Child and Adolescent Psychiatry, Hôpital Robert Debré, APHP, Paris, France
| | - Richard Delorme
- Department of Child and Adolescent Psychiatry, Hôpital Robert Debré, APHP, Paris, France
| | - Michael Schön
- Institute for Anatomy and Cell Biology, Ulm University, Ulm, Germany
| | - Andreas M Grabrucker
- Bernal Institute, University of Limerick, Limerick, Ireland; Dept. of Biological Sciences, University of Limerick, Limerick, Ireland; Health Research Institute HRI, University of Limerick, Limerick, Ireland
| | - Conny van Ravenswaaij-Arts
- University of Groningen, University Medical Center Groningen, Department of Genetics, Groningen, Netherlands
| | - Katy Phelan
- Genetics Laboratory, Florida Cancer Specialists & Research Institute, Fort Myers, FL, 33916, USA
| | | | - Thomas Bourgeron
- Génétique Humaine et Fonctions Cognitives, Institut Pasteur, UMR3571 CNRS, Université de Paris Cité, IUF, 75015, Paris, France.
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Wang Y, Zhao Z, Fu X, Li S, Zhang Q, Kong X. Detection of a Cryptic 25 bp Deletion and a 269 Kb Microduplication by Nanopore Sequencing in a Seemingly Balanced Translocation Involving the LMLN and LOC105378102 Genes. Front Genet 2022; 13:883398. [PMID: 36110201 PMCID: PMC9469083 DOI: 10.3389/fgene.2022.883398] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Accepted: 06/07/2022] [Indexed: 12/03/2022] Open
Abstract
Preimplantation genetic testing plays a critical role in enabling a balanced translocation carrier to obtain the normal embryo. Identifying the precise breakpoints for the carriers with phenotypic abnormity, allows us to reveal disrupted genes. In this study, a seemingly balanced translocation 46, XX, t (3; 6) (q29; q26) was first detected using conventional karyotype analysis. To locate the precise breakpoints, whole genomes of DNA were sequenced based on the nanopore GridION platform, and bioinformatic analyses were further confirmed by polymerase-chain-reaction (PCR) and copy number variation (CNV). Nanopore sequencing results were consistent with the karyotype analysis. Meanwhile, two breakpoints were successfully validated using polymerase-chain-reaction and Sanger Sequencing. LOC105378102 and LMLN genes were disrupted at the breakpoint junctions. Notably, observations found that seemingly balanced translocation was unbalanced due to a cryptic 269 kilobases (Kb) microduplication and a 25 bp deletion at the breakpoints of chromosome (chr) 6 and chr 3, respectively. Furthermore, 269 Kb microduplication was also confirmed by copy number variation analyses. In summary, nanopore sequencing was a rapid and direct method for identifying the precise breakpoints of a balanced translocation despite low coverage (3.8×). In addition, cryptic deletion and duplication were able to be detected at the single-nucleotide level.
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Leitão F, Grangeia A, Pinto J, Passas A, Dória S. Clinical Findings on Chromosome 1 Copy Number Variations. Neuropediatrics 2022; 53:265-273. [PMID: 35835157 DOI: 10.1055/s-0042-1754162] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Copy number variants (CNVs) are a major contribution to genome variability, and the presence of CNVs on chromosome 1 is a known cause of morbidity. The main objective of this study was to contribute to chromosome 1 disease map, through the analysis of patients with chromosome 1 CNVs.A cross-sectional study was performed using the array comparative genomic hybridization database of the Genetic Department of the Faculty of Medicine. Patients with pathogenic (P) or likely pathogenic (LP) CNVs on chromosome 1 were selected for the study. Clinical information was collected for all patients. Databases and related literature were used for genotype-phenotype correlation.From a total of 2,516 patients included in the database we identified 24 patients (0.95%) with P (9 patients) or LP (15 patients) CNVs on chromosome 1. These CNVs account for 6.1% (24/392 CNVs) of the total P/LP CNVs in the database. Most common CNVs found were in the 1q21.1-1q21.2 region.This study reinforces the association between chromosome 1 CNV and neurodevelopmental disorders and craniofacial dysmorphisms. Additionally, it also strengthened the idea that CNVs interpretation is not always a linear task due to the broad spectrum of variants that can be identified between benign and clearly pathogenic CNVs.
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Affiliation(s)
- Filipa Leitão
- Department of Pathology, Genetics Service, Faculty of Medicine, University of Porto, Porto, Portugal
| | - Ana Grangeia
- Department of Pathology, Genetics Service, Faculty of Medicine, University of Porto, Porto, Portugal.,Medical Genetics Service, Centro Hospitalar Universitário de São João, Porto, Portugal.,I3S-Instituto de Investigação e Inovação em Saúde, University of Porto, Porto, Portugal
| | - Joel Pinto
- Department of Pathology, Genetics Service, Faculty of Medicine, University of Porto, Porto, Portugal.,I3S-Instituto de Investigação e Inovação em Saúde, University of Porto, Porto, Portugal
| | - Armanda Passas
- Neurodevelopment Unit- UNIA, Centro Hospitalar Vila Nova de Gaia/Espinho - CHVNG, Vila Nova de Gaia, Portugal
| | - Sofia Dória
- Department of Pathology, Genetics Service, Faculty of Medicine, University of Porto, Porto, Portugal.,I3S-Instituto de Investigação e Inovação em Saúde, University of Porto, Porto, Portugal
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