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Yokoyama-Rebollar E, Ruiz-Herrera A, Lieberman-Hernández E, Del Castillo-Ruiz V, Sánchez-Sandoval S, Ávila-Flores SM, Castrillo JL. Angelman Syndrome due to familial translocation: unexpected additional results characterized by Microarray-based Comparative Genomic Hybridization. Mol Cytogenet 2015; 8:27. [PMID: 25901183 PMCID: PMC4404657 DOI: 10.1186/s13039-015-0127-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Accepted: 03/16/2015] [Indexed: 11/10/2022] Open
Abstract
Background The 15q11q13 region is subject to imprinting and is involved in various structural rearrangements. Less than 1% of Angelman Syndrome patients are due to translocations involving 15q11q13. These translocations can arise de novo or result from the segregation of chromosomes involved in a familial balanced translocation. Results A 5-year-old Mexican girl presented with developmental delay, minor dysmorphic features and history of exotropia. G-banding chromosome analysis established the diagnosis of Angelman Syndrome resulting from a familial translocation t(10;15) involving the 15q11.2 region. The available family members were studied using banding and molecular cytogenetic techniques, including Microarray-based Comparative Genomic Hybridization, which revealed additional unexpected results: a coincidental and smaller 15q deletion, asymptomatic duplications in 15q11.2 and Xp22.31 regions. Conclusions This report demonstrates the usefulness of array CGH for a detailed characterization of familial translocations, including the detection of submicroscopic copy number variations, which would otherwise be missed by karyotype analysis alone. Our report also expands two molecularly characterized rare patient cohorts: Angelman Syndrome patients due to familial translocations and patients with 15q11.2 duplications of paternal origin.
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Schneider A, Puechberty J, Ng BL, Coubes C, Gatinois V, Tournaire M, Girard M, Dumont B, Bouret P, Magnetto J, Baghdadli A, Pellestor F, Geneviève D. Identification of disrupted AUTS2 and EPHA6 genes by array painting in a patient carrying a de novo balanced translocation t(3;7) with intellectual disability and neurodevelopment disorder. Am J Med Genet A 2015; 167A:3031-7. [PMID: 26333717 DOI: 10.1002/ajmg.a.37350] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2015] [Accepted: 08/12/2015] [Indexed: 11/09/2022]
Abstract
Intellectual disability (ID) is a frequent feature but is highly clinically and genetically heterogeneous. The establishment of the precise diagnosis in patients with ID is challenging due to this heterogeneity but crucial for genetic counseling and appropriate care for the patients. Among the etiologies of patients with ID, apparently balanced de novo rearrangements represent 0.6%. Several mechanisms explain the ID in patients with apparently balanced de novo rearrangement. Among them, disruption of a disease gene at the breakpoint, is frequently evoked. In this context, technologies recently developed are used to characterize precisely such chromosomal rearrangements. Here, we report the case of a boy with ID, facial features and autistic behavior who is carrying a de novo balanced reciprocal translocation t(3;7)(q11.2;q11.22)dn. Using microarray analysis, array painting (AP) technology combined with molecular study, we have identified the interruption of the autism susceptibility candidate 2 gene (AUTS2) and EPH receptor A6 gene (EPHA6). We consider that the disruption of AUTS2 explains the phenotype of the patient; the exact role of EPHA6 in human pathology is not well defined. Based on the observation of recurrent germinal and somatic translocations involving AUTS2 and the molecular environment content, we put forward the hypothesis that the likely chromosomal mechanism responsible for the translocation could be due either to replicative stress or to recombination-based mechanisms.
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Affiliation(s)
- Anouck Schneider
- Laboratoire de Génétique Chromosomique, Plateforme de puces à ADN, CHRU de Montpellier, France
| | | | - Bee Ling Ng
- Cytometry Core Facility, The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, United Kingdom
| | | | - Vincent Gatinois
- Laboratoire de Génétique Chromosomique, Plateforme de puces à ADN, CHRU de Montpellier, France
| | - Magali Tournaire
- Laboratoire de Génétique Chromosomique, Plateforme de puces à ADN, CHRU de Montpellier, France
| | - Manon Girard
- Laboratoire de Génétique Chromosomique, Plateforme de puces à ADN, CHRU de Montpellier, France
| | - Bruno Dumont
- Laboratoire de Génétique Chromosomique, Plateforme de puces à ADN, CHRU de Montpellier, France
| | - Pauline Bouret
- Laboratoire de Génétique Chromosomique, Plateforme de puces à ADN, CHRU de Montpellier, France
| | - Julia Magnetto
- CRA, Département de Psychiatrie de l'Enfant et de l'Adolescent, Centre de Ressources Autisme, CHRU de Montpellier, France
| | - Amaria Baghdadli
- CRA, Département de Psychiatrie de l'Enfant et de l'Adolescent, Centre de Ressources Autisme, CHRU de Montpellier, France
| | - Franck Pellestor
- Laboratoire de Génétique Chromosomique, Plateforme de puces à ADN, CHRU de Montpellier, France
| | - David Geneviève
- Laboratoire de Génétique Chromosomique, Plateforme de puces à ADN, CHRU de Montpellier, France.,Département de Génétique Médicale, CHRU de Montpellier, France
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3
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Poot M, Haaf T. Mechanisms of Origin, Phenotypic Effects and Diagnostic Implications of Complex Chromosome Rearrangements. Mol Syndromol 2015; 6:110-34. [PMID: 26732513 DOI: 10.1159/000438812] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/23/2015] [Indexed: 01/08/2023] Open
Abstract
Complex chromosome rearrangements (CCRs) are currently defined as structural genome variations that involve more than 2 chromosome breaks and result in exchanges of chromosomal segments. They are thought to be extremely rare, but their detection rate is rising because of improvements in molecular cytogenetic technology. Their population frequency is also underestimated, since many CCRs may not elicit a phenotypic effect. CCRs may be the result of fork stalling and template switching, microhomology-mediated break-induced repair, breakage-fusion-bridge cycles, or chromothripsis. Patients with chromosomal instability syndromes show elevated rates of CCRs due to impaired DNA double-strand break responses during meiosis. Therefore, the putative functions of the proteins encoded by ATM, BLM, WRN, ATR, MRE11, NBS1, and RAD51 in preventing CCRs are discussed. CCRs may exert a pathogenic effect by either (1) gene dosage-dependent mechanisms, e.g. haploinsufficiency, (2) mechanisms based on disruption of the genomic architecture, such that genes, parts of genes or regulatory elements are truncated, fused or relocated and thus their interactions disturbed - these mechanisms will predominantly affect gene expression - or (3) mixed mutation mechanisms in which a CCR on one chromosome is combined with a different type of mutation on the other chromosome. Such inferred mechanisms of pathogenicity need corroboration by mRNA sequencing. Also, future studies with in vitro models, such as inducible pluripotent stem cells from patients with CCRs, and transgenic model organisms should substantiate current inferences regarding putative pathogenic effects of CCRs. The ramifications of the growing body of information on CCRs for clinical and experimental genetics and future treatment modalities are briefly illustrated with 2 cases, one of which suggests KDM4C (JMJD2C) as a novel candidate gene for mental retardation.
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Affiliation(s)
- Martin Poot
- Department of Human Genetics, University of Würzburg, Würzburg, Germany
| | - Thomas Haaf
- Department of Human Genetics, University of Würzburg, Würzburg, Germany
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Seidel MG, Duerr C, Woutsas S, Schwerin-Nagel A, Sadeghi K, Neesen J, Uhrig S, Santos-Valente E, Pickl WF, Schwinger W, Urban C, Boztug K, Förster-Waldl E. A novel immunodeficiency syndrome associated with partial trisomy 19p13. J Med Genet 2014; 51:254-63. [PMID: 24431329 PMCID: PMC3963557 DOI: 10.1136/jmedgenet-2013-102122] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Background Subtelomeric deletions and duplications may cause syndromic disorders that include features of immunodeficiency. To date, no phenotype of immunological pathology has been linked to partial trisomy 19. We report here on two unrelated male patients showing clinical and laboratory signs of immunodeficiency exhibiting a duplication involving Chromosome 19p13. Methods Both patients underwent a detailed clinical examination. Extended laboratory investigations for immune function, FISH and array comparative genome hybridization (CGH) analyses were performed. Results The reported patients were born prematurely with intrauterine growth retardation and share clinical features including neurological impairment, facial dysmorphy and urogenital malformations. Array CGH analyses of both patients showed a largely overlapping terminal duplication affecting Chromosome 19p13. In both affected individuals, the clinical course was marked by recurrent severe infections. Signs of humoral immunodeficiency were detected, including selective antibody deficiency against polysaccharide antigens in patient 1 and reduced IgG1, IgG3 subclass levels and IgM deficiency in patient 2. Class-switched B memory cells were almost absent in both patients. Normal numbers of T cells, B cells and natural killer cells were observed in both boys. Lymphocytic proliferation showed no consistent functional pathology, however, function of granulocytes and monocytes as assessed by oxidative burst test was moderately reduced. Moreover, natural killer cytotoxicity was reduced in both patients. Immunoglobulin substitution resulted in a decreased number and severity of infections and improved thriving in both patients. Conclusions Partial trisomy 19p13 represents a syndromic disorder associating organ malformation and hitherto unrecognised immunodeficiency.
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Affiliation(s)
- Markus G Seidel
- Divison of Pediatric Hematology-Oncology, Department Pediatrics and Adolescent Medicine, Medical University Graz, Graz, Austria
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5
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Madan K. What is a complex chromosome rearrangement? Am J Med Genet A 2013; 161A:1181-4. [PMID: 23532917 DOI: 10.1002/ajmg.a.35834] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2012] [Accepted: 12/06/2012] [Indexed: 11/06/2022]
Affiliation(s)
- Kamlesh Madan
- Department of Clinical Genetics, Leiden University Medical Center, Leiden, The Netherlands.
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6
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Madan K. Balanced complex chromosome rearrangements: Reproductive aspects. A review. Am J Med Genet A 2012; 158A:947-63. [DOI: 10.1002/ajmg.a.35220] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2011] [Accepted: 12/07/2011] [Indexed: 11/05/2022]
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Characterising chromosome rearrangements: recent technical advances in molecular cytogenetics. Heredity (Edinb) 2011; 108:75-85. [PMID: 22086080 PMCID: PMC3238113 DOI: 10.1038/hdy.2011.100] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Genomic rearrangements can result in losses, amplifications, translocations and inversions of DNA fragments thereby modifying genome architecture, and potentially having clinical consequences. Many genomic disorders caused by structural variation have initially been uncovered by early cytogenetic methods. The last decade has seen significant progression in molecular cytogenetic techniques, allowing rapid and precise detection of structural rearrangements on a whole-genome scale. The high resolution attainable with these recently developed techniques has also uncovered the role of structural variants in normal genetic variation alongside single-nucleotide polymorphisms (SNPs). We describe how array-based comparative genomic hybridisation, SNP arrays, array painting and next-generation sequencing analytical methods (read depth, read pair and split read) allow the extensive characterisation of chromosome rearrangements in human genomes.
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Pellestor F, Anahory T, Lefort G, Puechberty J, Liehr T, Hedon B, Sarda P. Complex chromosomal rearrangements: origin and meiotic behavior. Hum Reprod Update 2011; 17:476-94. [DOI: 10.1093/humupd/dmr010] [Citation(s) in RCA: 113] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
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Gruchy N, Barreau M, Kessler K, Gourdier D, Leporrier N. A paternally transmitted complex chromosomal rearrangement (CCR) involving chromosomes 2, 6, and 18 includes eight breakpoints and five insertional translocations (ITs) through three generations. Am J Med Genet A 2010; 152A:185-90. [PMID: 20034065 DOI: 10.1002/ajmg.a.33154] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Complex chromosomal rearrangements (CCRs) are uncommon and mainly occur de novo. We report here on a familial CCR involving chromosomes 2, 6, and 18. The propositus is a boy first referred because of growth delays, hypotonia, and facial anomalies, suggestive of deletion 18q syndrome. However, a cytogenetic family study disclosed a balanced CCR in three generations, which was detailed by FISH using BAC clones, and consisted of eight breakpoints with five insertional translocations (ITs). The propositus had a cryptic 18q deletion and a 6p duplication. Paternal transmission of this CCR was observed through three generations without meiotic recombination. Our investigation allowed us to provide porosities counseling and management of prenatal diagnosis for propositus cousin who carries this particular CCR.
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Affiliation(s)
- Nicolas Gruchy
- Laboratoire de cytogénétique prénatale niveau 3, Centre Hospitalier Universitaire de Caen, Avenue Côte de Nacre, 14033 Caen Cedex, France.
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10
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Gribble SM, Ng BL, Prigmore E, Fitzgerald T, Carter NP. Array painting: a protocol for the rapid analysis of aberrant chromosomes using DNA microarrays. Nat Protoc 2009; 4:1722-36. [PMID: 19893508 PMCID: PMC3330750 DOI: 10.1038/nprot.2009.183] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Array painting is a technique that uses microarray technology to rapidly map chromosome translocation breakpoints. Previous methods to map translocation breakpoints have used fluorescence in situ hybridization (FISH) and have consequently been labor-intensive, time-consuming and restricted to the low breakpoint resolution imposed by the use of metaphase chromosomes. Array painting combines the isolation of derivative chromosomes (chromosomes with translocations) and high-resolution microarray analysis to refine the genomic location of translocation breakpoints in a single experiment. In this protocol, we describe array painting by isolation of derivative chromosomes using a MoFlo flow sorter, amplification of these derivatives using whole-genome amplification and hybridization onto commercially available oligonucleotide microarrays. Although the sorting of derivative chromosomes is a specialized procedure requiring sophisticated equipment, the amplification, labeling and hybridization of DNA is straightforward, robust and can be completed within 1 week. The protocol described produces good quality data; however, array painting is equally achievable using any combination of the available alternative methodologies for chromosome isolation, amplification and hybridization.
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Affiliation(s)
- Susan M Gribble
- Human Genetics, Sulston Laboratories, The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Cambridge, UK.
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11
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Lu X, Shaw CA, Patel A, Li J, Cooper ML, Wells WR, Sullivan CM, Sahoo T, Yatsenko SA, Bacino CA, Stankiewicz P, Ou Z, Chinault AC, Beaudet AL, Lupski JR, Cheung SW, Ward PA. Clinical implementation of chromosomal microarray analysis: summary of 2513 postnatal cases. PLoS One 2007; 2:e327. [PMID: 17389918 PMCID: PMC1828620 DOI: 10.1371/journal.pone.0000327] [Citation(s) in RCA: 178] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2006] [Accepted: 03/05/2007] [Indexed: 11/20/2022] Open
Abstract
BACKGROUND Array Comparative Genomic Hybridization (a-CGH) is a powerful molecular cytogenetic tool to detect genomic imbalances and study disease mechanism and pathogenesis. We report our experience with the clinical implementation of this high resolution human genome analysis, referred to as Chromosomal Microarray Analysis (CMA). METHODS AND FINDINGS CMA was performed clinically on 2513 postnatal samples from patients referred with a variety of clinical phenotypes. The initial 775 samples were studied using CMA array version 4 and the remaining 1738 samples were analyzed with CMA version 5 containing expanded genomic coverage. Overall, CMA identified clinically relevant genomic imbalances in 8.5% of patients: 7.6% using V4 and 8.9% using V5. Among 117 cases referred for additional investigation of a known cytogenetically detectable rearrangement, CMA identified the majority (92.5%) of the genomic imbalances. Importantly, abnormal CMA findings were observed in 5.2% of patients (98/1872) with normal karyotypes/FISH results, and V5, with expanded genomic coverage, enabled a higher detection rate in this category than V4. For cases without cytogenetic results available, 8.0% (42/524) abnormal CMA results were detected; again, V5 demonstrated an increased ability to detect abnormality. Improved diagnostic potential of CMA is illustrated by 90 cases identified with 51 cryptic microdeletions and 39 predicted apparent reciprocal microduplications in 13 specific chromosomal regions associated with 11 known genomic disorders. In addition, CMA identified copy number variations (CNVs) of uncertain significance in 262 probands; however, parental studies usually facilitated clinical interpretation. Of these, 217 were interpreted as familial variants and 11 were determined to be de novo; the remaining 34 await parental studies to resolve the clinical significance. CONCLUSIONS This large set of clinical results demonstrates the significantly improved sensitivity of CMA for the detection of clinically relevant genomic imbalances and highlights the need for comprehensive genetic counseling to facilitate accurate clinical correlation and interpretation.
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Affiliation(s)
- Xinyan Lu
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Chad A. Shaw
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Ankita Patel
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Jiangzhen Li
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - M. Lance Cooper
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - William R. Wells
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Cathy M. Sullivan
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Trilochan Sahoo
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Svetlana A. Yatsenko
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Carlos A. Bacino
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Pawel Stankiewicz
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Zhishu Ou
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - A. Craig Chinault
- Department of Molecular and Human Genetics, 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
| | - James R. Lupski
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Sau W. Cheung
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Patricia A. Ward
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
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12
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Joly-Helas G, de La Rochebrochard C, Mousset-Siméon N, Moirot H, Tiercin C, Romana SP, Le Caignec C, Clavier B, Macé B, Rives N. Complex chromosomal rearrangement and intracytoplasmic sperm injection: a case report. Hum Reprod 2007; 22:1292-7. [PMID: 17283038 DOI: 10.1093/humrep/del507] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Complex chromosomal rearrangements (CCRs) are rare events in human pathology and are usually considered to induce severe reproductive impairment by disturbing the meiotic process and producing unbalanced gametes responsible for high reproductive risk. One-third of all CCRs are familial and tend to implicate fewer breakpoints and fewer chromosomes than de novo cases. CCRs are rarely transmitted through spermatogenesis and are primarily ascertained by male infertility. We report a familial balanced CCR, with seven breakpoints involving three chromosomes, which was detected prenatally in a female fetus conceived after intracytoplasmic sperm injection (ICSI) in a couple initially thought to be a carrier of a paternal reciprocal translocation involving two chromosomal breakpoints. Fluorescent in-situ hybridization (FISH) was used to elucidate the complexity of this CCR. The karyotype of the female CCR carrier was balanced and determined as 46,XX.ish t(1;4)(q42;q32)(WCP1+, D1Z5+, WCP4+, D1S3738-, D4S2930+; WCP4+, D4Z1+, WCP1+, D4S2930-, D1S3738+), ins(1;11)(q41;q23q24)(WCP1+,WCP11+, D11S2071-, MLL+; WCP11+, D11S2071+, WCP1-, MLL-), ins(4;11)(q23;q14q23)(WCP4+,WCP11+; WCP11+,WCP4-). The same balanced CCR was confirmed in her oligozoospermic father. We report, to our knowledge, the first case of ICSI performed in an infertile male with CCR, resulting in a balanced CCR carrier female with a normal clinical follow-up at 4 years of age. This particular case stresses the point of the relevance and feasibility of ICSI procedure in cases of balanced CCRs.
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MESH Headings
- Adult
- Amniocentesis
- Azoospermia/genetics
- Chromosomes, Human, Pair 1/genetics
- Chromosomes, Human, Pair 11/genetics
- Chromosomes, Human, Pair 4/genetics
- Female
- Humans
- In Situ Hybridization, Fluorescence
- Infant, Newborn
- Male
- Pregnancy
- Pregnancy Outcome
- Sperm Injections, Intracytoplasmic
- Translocation, Genetic/genetics
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Affiliation(s)
- G Joly-Helas
- Laboratory of Cytogenetics, Rouen University Hospital, Rouen Cedex, France.
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13
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Carbone L, Vessere GM, ten Hallers BFH, Zhu B, Osoegawa K, Mootnick A, Kofler A, Wienberg J, Rogers J, Humphray S, Scott C, Harris RA, Milosavljevic A, de Jong PJ. A high-resolution map of synteny disruptions in gibbon and human genomes. PLoS Genet 2006; 2:e223. [PMID: 17196042 PMCID: PMC1756914 DOI: 10.1371/journal.pgen.0020223] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2006] [Accepted: 11/13/2006] [Indexed: 12/22/2022] Open
Abstract
Gibbons are part of the same superfamily (Hominoidea) as humans and great apes, but their karyotype has diverged faster from the common hominoid ancestor. At least 24 major chromosome rearrangements are required to convert the presumed ancestral karyotype of gibbons into that of the hominoid ancestor. Up to 28 additional rearrangements distinguish the various living species from the common gibbon ancestor. Using the northern white-cheeked gibbon (2n = 52) (Nomascus leucogenys leucogenys) as a model, we created a high-resolution map of the homologous regions between the gibbon and human. The positions of 100 synteny breakpoints relative to the assembled human genome were determined at a resolution of about 200 kb. Interestingly, 46% of the gibbon–human synteny breakpoints occur in regions that correspond to segmental duplications in the human lineage, indicating a common source of plasticity leading to a different outcome in the two species. Additionally, the full sequences of 11 gibbon BACs spanning evolutionary breakpoints reveal either segmental duplications or interspersed repeats at the exact breakpoint locations. No specific sequence element appears to be common among independent rearrangements. We speculate that the extraordinarily high level of rearrangements seen in gibbons may be due to factors that increase the incidence of chromosome breakage or fixation of the derivative chromosomes in a homozygous state. It is commonly accepted that mammalian chromosomes have undergone a limited number of rearrangements during the course of more than 100 million years of evolution. Surprisingly, some species have experienced a large increase in the incidence of rearrangements, including translocations (exchange between two non-homologous chromosomes), inversions (change of orientation of one chromosomal segment), fissions, and fusions. Within the primate order, gibbons exhibit the most strikingly unstable chromosome pattern. Gibbon chromosomal structure greatly differs from that of their most recent common ancestor with humans from which they diverged over 15 million years ago. The authors are interested in the mechanisms causing this extraordinary instability. In this study, they employed modern techniques to compare the human and white-cheeked gibbon chromosomes and to localize all the regions of disrupted homology between the two species. Their findings indicate that the molecular mechanism of gibbon chromosomal reshuffling is based on the same principles as in other mammalian species. To explain the 10-fold higher incidence of gibbon chromosomal rearrangements, it will be necessary to pursue future studies into other biological factors such as inbreeding and population dynamics.
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Affiliation(s)
- Lucia Carbone
- BACPAC Resources, Children's Hospital of Oakland Research Institute, Oakland, California, United States of America.
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14
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Schwarzbraun T, Ullmann R, Schubert M, Ledinegg M, Ofner L, Windpassinger C, Wagner K, Kroisel PM, Petek E. Characterization of a de novo complex chromosome rearrangement (CCR) involving chromosomes 2 and 12, associated with mental retardation and impaired speech development. Cytogenet Genome Res 2006; 115:84-9. [PMID: 16974087 DOI: 10.1159/000094804] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2005] [Accepted: 03/09/2006] [Indexed: 11/19/2022] Open
Abstract
We report on a currently six-year-old patient with a de novo complex chromosome rearrangement (CCR) involving chromosomes 2 and 12. A translocation 2;12 that appeared to be reciprocal after standard banding turned out to be a complex event with seven breaks after molecular cytogenetic analyses. Array CGH analysis showed no imbalances at the breakpoints but revealed an additional microdeletion of about 80 kb on chromosome 11. The same deletion was also present in the phenotypically normal father. The patient showed relatively mild mental retardation, defined mainly as impaired speech development (orofacial dyspraxia) and psychomotor retardation. In addition, mild dysmorphic facial features like hypertelorism, a prominent philtrum and down-turned corners of the mouth were observed. We narrowed down all breakpoint regions to about 100 kb, using a panel of mapped bacterial artificial chromosome (BAC) clones for fluorescence in situ hybridization (FISH). BACs spanning or flanking all seven breakpoints were identified and no chromosomal imbalances were found consistent with the array CGH results. Our investigations resulted in the following karyotype: 46,XY,t(2;12)(2pter-->2p25.3::2p23.3-->2p25.2::2p23.3-->2p14::2q14.3-->2p14::2q14.3-->2q14.3::12q 12-->12qter;12pter-->12q12::2p25.3-->2p25.2::2q14.3-->2qter).
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Affiliation(s)
- T Schwarzbraun
- Institute of Medical Biology and Human Genetics, Medical University Graz, Austria
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Langer S, Geigl JB, Wagenstaller J, Lederer G, Hempel M, Daumer-Haas C, Leifheit HJ, Speicher MR. Delineation of a 2q deletion in a girl with dysmorphic features and epilepsy. Am J Med Genet A 2006; 140:764-8. [PMID: 16523518 DOI: 10.1002/ajmg.a.31141] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
In recent years, the spectrum of available methods for the characterization of chromosomal aberrations has significantly increased. Micro-array technologies now allow the rapid fine mapping of small genomic imbalances. Here we used various technologies to characterize a de novo translocation t(2;15) in a girl with dysmorphic features, severe developmental delay and frequent seizures. Multiplex-FISH (M-FISH) excluded the involvement of other chromosomes than chromosomes 2 and 15. We used an oligonucleotide array containing more than 10.000 SNPs, that is, the GeneChip Mapping 10K 2.0 SNP Affymetrix array, and readily fine-mapped a deletion in chromosomal region 2q24.1 --> 2q31.1. The extent of this deletion was verified with multicolor BAC-clone hybridizations. The deletion has a size of about 13 Mb and is within a gene rich region containing about 76 genes. Interestingly, several of these genes are ion channel genes or genes involved in neuron differentiation, so that the frequently occurring seizures are probably due to loss or haploinsufficiency of one or more of these genes.
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Affiliation(s)
- Sabine Langer
- Institut für Humangenetik, Technische Universität München, München, Germany
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