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Quinonez SC, Gelehrter TD, Uhlmann WR. A Marfan syndrome-like phenotype caused by a neocentromeric supernumerary ring chromosome 15. Am J Med Genet A 2016; 173:268-273. [PMID: 27739187 DOI: 10.1002/ajmg.a.38000] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Accepted: 09/26/2016] [Indexed: 11/10/2022]
Abstract
Small supernumerary marker chromosomes (sSMC) are abnormal chromosomes that cannot be characterized by standard banding cytogenetic techniques. A minority of sSMC contain a neocentromere, which is an ectopic centromere lacking the characteristic alpha-satellite DNA. The phenotypic manifestations of sSMC and neocentromeric sSMC are variable and range from severe intellectual disability and multiple congenital anomalies to a normal phenotype. Here we report a patient with a diagnosis of Marfan syndrome and infertility found to have an abnormal karyotype consisting of a chromosome 15 deletion and a ring-type sSMC likely stabilized by a neocentromere derived via a mechanism initially described by Barbara McClintock in 1938. Analysis of the sSMC identified that it contained the deleted chromosome 15 material and also one copy of FBN1, the gene responsible for Marfan syndrome. We propose that the patient's diagnosis arose from disruption of the FBN1 allele on the sSMC. To date, a total of 29 patients have been reported with an sSMC derived from a chromosomal deletion. We review these cases with a specific focus on the resultant phenotypes and note significant difference between this class of sSMC and other types of sSMC. Through this review we also identified a patient with a clinical diagnosis of neurofibromatosis type 1 who lacked a family history of the condition but was found to have a chromosome 17-derived sSMC that likely contained NF1 and caused the patient's disorder. We also review the genetic counseling implications and recommendations for a patient or family harboring an sSMC. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Shane C Quinonez
- Department of Pediatrics and Communicable Diseases, University of Michigan Medical School, Ann Arbor, Michigan.,Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan
| | - Thomas D Gelehrter
- Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan.,Department of Human Genetics, University of Michigan, Ann Arbor, Michigan
| | - Wendy R Uhlmann
- Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan.,Department of Human Genetics, University of Michigan, Ann Arbor, Michigan
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Desch L, Marle N, Mosca-Boidron AL, Faivre L, Eliade M, Payet M, Ragon C, Thevenon J, Aral B, Ragot S, Ardalan A, Dhouibi N, Bensignor C, Thauvin-Robinet C, El Chehadeh S, Callier P. 6q16.3q23.3 duplication associated with Prader-Willi-like syndrome. Mol Cytogenet 2015; 8:42. [PMID: 26110021 PMCID: PMC4479069 DOI: 10.1186/s13039-015-0151-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2015] [Accepted: 06/10/2015] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Prader-Willi syndrome (PWS) is characterized by hypotonia, delayed neuropsychomotor development, overeating, obesity and mental deficiency. This phenotype is encountered in other conditions, defining Prader-Willi-like syndrome (PWLS). CASE PRESENTATION We report a 14-year-old boy with a complex small supernumerary marker chromosome (sSMC) associated with PWLS. The propositus presents clinical features commonly found in patients with PWLS, including growth hormone deficit. Banding karyotype analysis and fluorescence in situ hybridization (FISH) revealed a marker derived from chromosome 6 and a neocentromere as suspected, but array-CGH enabled us to characterize this marker as a der(10)t(6;10)(6qter → 6q23.3::10p11.1 → 10p11.21)dn. As far as we know, this is the first diagnosed case of PWLS associated with a complex sSMC, involving a 30.9 Mb gain in the 6q16.3q23.3 region and a 3.5 Mb gain in the 10p11.21p11.1 region. Several genes have been mapped to the 6q region including the TCBA1 gene, which is associated with developmental delay and recurrent infections, the ENPP1 gene, associated with insulin resistance and susceptibility to obesity and the BMIQ3 gene, associated with body mass index (BMI). No OMIM gene was found in the smallest 10p11.21p11.1 region. CONCLUSIONS We suggest that the duplicated chromosome segment 6q16.3q23.3 may be responsible for the phenotype of our case and may also be a candidate locus of PWLS.
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Affiliation(s)
- Laurent Desch
- />Laboratoire de Cytogénétique, Plateau Technique de Biologie, CHU de Dijon, Dijon, France
| | - Nathalie Marle
- />Laboratoire de Cytogénétique, Plateau Technique de Biologie, CHU de Dijon, Dijon, France
| | | | - Laurence Faivre
- />Centre de référence maladies rares « anomalies du développement et syndromes malformatifs » de l’Est, Centre de Génétique, CHU de Dijon, Dijon, France
| | - Marie Eliade
- />Laboratoire de Cytogénétique, Plateau Technique de Biologie, CHU de Dijon, Dijon, France
| | - Muriel Payet
- />Laboratoire de Cytogénétique, Plateau Technique de Biologie, CHU de Dijon, Dijon, France
| | - Clemence Ragon
- />Laboratoire de Cytogénétique, Plateau Technique de Biologie, CHU de Dijon, Dijon, France
| | - Julien Thevenon
- />Laboratoire de Cytogénétique, Plateau Technique de Biologie, CHU de Dijon, Dijon, France
| | - Bernard Aral
- />Laboratoire de Cytogénétique, Plateau Technique de Biologie, CHU de Dijon, Dijon, France
| | - Sylviane Ragot
- />Laboratoire de Cytogénétique, Plateau Technique de Biologie, CHU de Dijon, Dijon, France
| | | | | | | | - Christel Thauvin-Robinet
- />Centre de référence maladies rares « anomalies du développement et syndromes malformatifs » de l’Est, Centre de Génétique, CHU de Dijon, Dijon, France
| | - Salima El Chehadeh
- />Centre de référence maladies rares « anomalies du développement et syndromes malformatifs » de l’Est, Centre de Génétique, CHU de Dijon, Dijon, France
| | - Patrick Callier
- />Laboratoire de Cytogénétique, Plateau Technique de Biologie, CHU de Dijon, Dijon, France
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Neira VA, Romero-Espinoza P, Rojas-Martínez A, Ortiz-López R, Córdova-Fletes C, Plaja A, Barros-Núñez P. De novo MECP2 disomy in a Mexican male carrying a supernumerary marker chromosome and no typical Lubs syndrome features. Gene 2013; 524:381-5. [PMID: 23639959 DOI: 10.1016/j.gene.2013.04.029] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2012] [Revised: 04/02/2013] [Accepted: 04/03/2013] [Indexed: 10/26/2022]
Abstract
Xq28 duplication, including the MECP2 gene, is among the most frequently identified Xq subtelomeric rearrangements. The resulting clinical phenotype is named Lubs syndrome and mainly consists of intellectual disability, congenital hypotonia, absent speech, recurrent infections, and seizures. Here we report a Mexican male patient carrying a supernumerary marker chromosome with de novo Xq28 gain. By MLPA, duplication of MECP2, GDI1, and SLC6A8 was found and a subsequent a-CGH analysis demonstrated that the gain spanned ~2.1Mb. Despite gain of the MECP2 gene, the features of this patient do not evoke Lubs syndrome. Probably the mosaicism of the supernumerary marker chromosome is modifying the phenotype in this patient.
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Affiliation(s)
- Vivian Alejandra Neira
- División de Genética, Centro de Investigación Biomédica de Occidente, CMNO-IMSS, Guadalajara, Jalisco, Mexico
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Vagnarelli P, Ribeiro SA, Earnshaw WC. Centromeres: old tales and new tools. FEBS Lett 2008; 582:1950-9. [PMID: 18435926 DOI: 10.1016/j.febslet.2008.04.014] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2008] [Accepted: 04/11/2008] [Indexed: 01/07/2023]
Abstract
The centromere is a specialised region of the eukaryotic chromosome that directs the equal segregation of sister chromatids into two daughter cells during mitosis. In mitosis, the kinetochores mediate (1) microtubule capture and chromosome alignment at a metaphase plate; (2) the correction of improper microtubule attachments; (3) the maintenance of an active checkpoint until bi-orientation is achieved by the whole complement of chromosomes; (4) the establishment of tension within the centromere which, in turn, contributes to silencing of the spindle checkpoint and triggers the onset of anaphase. In this review, we will analyse how centromeres are organised with respect to chromatin types and arrangements.
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Affiliation(s)
- P Vagnarelli
- Wellcome Trust Centre for Cell Biology, Institute of Cell and Molecular Biology, University of Edinburgh, Swann Building, King's Buildings, Mayfield Road, Edinburgh EH9 3JR, UK.
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