1
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Borjas-Gutierrez C, Gonzalez-Garcia JR. Philadelphia chromosome duplication as a ring-shaped chromosome. Mol Cytogenet 2016; 9:83. [PMID: 27895712 PMCID: PMC5117599 DOI: 10.1186/s13039-016-0292-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2016] [Accepted: 11/08/2016] [Indexed: 12/04/2022] Open
Abstract
The gain of a second copy of the Philadelphia chromosome is one of the main secondary chromosomal changes related to the clonal evolution of cells with t(9;22) in chronic myelogenous leukemia. This gain causes the acquisition of another copy of the BCR/ABL1 fusion gene. Isochromosomes of the der(22) chromosome or double minute chromosomes are well known to lead an increased copy number of BCR/ABL1 gene. There is no antecedent of Philadelphia chromosome duplication as a ring chromosome. A recent published report contains evidence that strongly suggests that the Philadelphia chromosome was duplicated as a ring chromosome, observation that was overlooked by the authors. The instability inherent to the ring chromosome increases the risk of emergence of clones containing more and more BCR/ABL1 gene copies, which would produce increased fitness for clonal selection, resulting in worsening of the patient’s prognosis.
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Affiliation(s)
- Cesar Borjas-Gutierrez
- Division de Genetica. Centro de Investigacion Biomedica de Occidente, Instituto Mexicano del Seguro Social, Sierra Mojada # 800. Colonia Independencia, CP 44340 Guadalajara, Jalisco Mexico ; Doctorado en Genetica Humana, CUCS-Universidad de Guadalajara, Guadalajara, Jalisco Mexico
| | - Juan Ramon Gonzalez-Garcia
- Division de Genetica. Centro de Investigacion Biomedica de Occidente, Instituto Mexicano del Seguro Social, Sierra Mojada # 800. Colonia Independencia, CP 44340 Guadalajara, Jalisco Mexico
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2
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Carella M, Spreafico F, Palumbo O, Storlazzi CT, Tabano S, Miozzo M, Miglionico L, Calvano S, Sindici G, Gamba B, Impera L, Collini P, Zelante L, Radice P, Perotti D. Constitutional ring chromosome 11 mosaicism in a Wilms tumor patient: Cytogenetic, molecular and clinico-pathological studies. Am J Med Genet A 2010; 152A:1756-63. [DOI: 10.1002/ajmg.a.33420] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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3
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Sodré CP, Guilherme RS, Meloni VFA, Brunoni D, Juliano Y, Andrade JAD, Belangero SIN, Christofolini DM, Kulikowski LD, Melaragno MI. Ring chromosome instability evaluation in six patients with autosomal rings. GENETICS AND MOLECULAR RESEARCH 2010; 9:134-43. [PMID: 20198569 DOI: 10.4238/vol9-1gmr707] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Ring chromosomes are often associated with abnormal phenotypes due to loss of genomic material and also because of ring instability at mitosis after sister chromatid exchange events. We investigated ring chromosome instability in six patients with ring chromosomes 4, 14, 15, and 18 by examining 48- and 72-h lymphocyte cultures at the first, second and subsequent cell divisions after bromodeoxyuridine incorporation. Although most cells from all patients showed only one monocentric ring chromosome, ring chromosome loss and secondary aberrations were observed both in 48- and 72-h lymphocyte cultures and in metaphase cells of the different cell generations. We found no clear-cut correlation between ring size and ring instability; we also did not find differences between apparently complete rings and rings with genetic material loss. The cytogenetic findings revealed secondary aberrations in all ring chromosome patients. We concluded that cells with ring chromosome instability can multiply and survive in vivo, and that they can influence the patient's phenotype.
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Affiliation(s)
- C P Sodré
- Departamento de Morfologia e Genética da Universidade Federal de São Paulo, São Paulo, SP, Brasil
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4
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Rivera H, Domínguez MG. Variegated aneuploidy and ring chromosome syndromes overlap. Am J Med Genet A 2009; 152A:228-9. [PMID: 20034077 DOI: 10.1002/ajmg.a.33195] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Horacio Rivera
- División de Genética, CIBO, Instituto Mexicano del Seguro Social, Ap. Postal 1-3838, Guadalajara, Mexico.
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5
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Purandare SM, Lee J, Hassed S, Steele MI, Blackett PR, Mulvihill JJ, Li S. Ring chromosome 9 [r(9)(p24q34)]: a report of two cases. Am J Med Genet A 2008; 138A:229-35. [PMID: 16158426 DOI: 10.1002/ajmg.a.30382] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
We report clinical and molecular cytogenetic studies in two patients with ring chromosome 9. Cytogenetics and fluorescent in situ hybridization (FISH) analysis using the p16 gene probe on 9p21, the ABL gene on 9q34, chromosome 9 alpha satellite-centromeric probes, and TelVision 9p and 9q probes which identify subtelomere-specific sequences on chromosome 9p and 9q, revealed 46,XX,r(9)(p24q34).ish r(9)(305J7-T7-,p16+,ABL+, D9S325-) and 46XY,r(9)(p24q34).ish r(9)(305J7-T7-,p16+,ABL+, D9S325-). Based on FISH analysis at least 115 kb was deleted on terminal 9p, and at least 95 kb from terminal 9q. In comparison with other reports of r(9), deletion 9p, and deletion 9q, both patients had clinical characteristics of ring 9 and additional features of deletion 9q or deletion 9p syndrome. The variability between the two cases with r(9) despite similar breakpoints identified by GTG-banding and FISH may be explained by submicroscopic differences between deletion breakpoints, ring instability, interaction of other genes on the phenotype, and variation in fetal environmental conditions.
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Affiliation(s)
- Smita M Purandare
- Department of Pediatrics, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
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6
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Park YM, Nho HN, Kim SZ, Ahn YM. Cytogenetic evaluation of a patient with ring chromosome 9 presenting failure to thrive and developmental delay. KOREAN JOURNAL OF PEDIATRICS 2008. [DOI: 10.3345/kjp.2008.51.4.426] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Yun Mi Park
- Department of Laboratory Medicine, Eulji University School of Medicine, Seoul, Korea
| | - Han Nae Nho
- Department of Pediatrics, Eulji University School of Medicine, Korea
| | - Sook Za Kim
- Department of Korea Genetics Research Center, Seoul, Korea
| | - Young Min Ahn
- Department of Pediatrics, Eulji University School of Medicine, Korea
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7
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Association of microcephaly and caf??-au-lait spots in a patient with ring chromosome 12 syndrome. Clin Dysmorphol 2005. [DOI: 10.1097/00019605-200507000-00007] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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8
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Le Caignec C, Boceno M, Jacquemont S, Nguyen The Tich S, Rival JM, David A. Inherited ring chromosome 8 without loss of subtelomeric sequences. ACTA ACUST UNITED AC 2004; 47:289-96. [PMID: 15337475 DOI: 10.1016/j.anngen.2003.10.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2003] [Accepted: 10/16/2003] [Indexed: 11/15/2022]
Abstract
We report the first case of inherited ring chromosome 8 syndrome without loss of subtelomeric sequences. The proband is a 6 1/2-year-old boy with short stature, microcephaly, mild mental retardation, and behavioral problems including hyperactivity and attention deficit. His mother presented the same physical features but intelligence was normal. Family history also revealed an uncle and a grandmother, with short stature and microcephaly. Moderate mental retardation was reported in the uncle. Karyotypes and fluorescence in situ hybridization (FISH) analyses were performed on peripheral blood lymphocytes for both child and mother. The child's karyotype was reported as 46,XY,r(8)(p23q24.3)[24]/45,XY,-8[2] and the mother's karyotype 46,XX,r(8)(p23q24.3)[22]/45,XX,-8[2]/47,XX,r(8)(p23q24.3), +r(8)(p23q24.3)[1]. FISH studies showed no deletion of subtelomeric sequences for both child and mother indicating that no or little chromosomal euchromatic material has been deleted. These findings indicate that ring chromosome 8 without loss of subtelomeric sequences can be inherited and that carriers in a same family present with cognitive function ranging from mild mental retardation to normal intelligence.
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Affiliation(s)
- Cedric Le Caignec
- Service de Génétique Médicale, Plateau Technique, Centre Hospitalo-Universitaire, 9, quai Moncousu, 44093 Nantes cedex, France.
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9
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Shashi V, White JR, Pettenati MJ, Root SK, Bell WL. Ring chromosome 17: phenotype variation by deletion size. Clin Genet 2003; 64:361-5. [PMID: 12974742 DOI: 10.1034/j.1399-0004.2003.00146.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Ring chromosome 17 is a rare cytogenetic abnormality, with 12 previous reports in the literature. Some have a relatively mild phenotype characterized by seizures, mental retardation, skin changes and short stature. Other patients have Miller-Dieker syndrome (MDS), which includes lissencephaly, multiple dysmorphic features, severe mental retardation and shortened life expectancy. We describe two new cases of ring chromosome 17 and review the literature. Our cases and the other reports of patients without a deletion encompassing the Miller-Dieker region, delineate a fairly distinctive subgroup of individuals with ring 17, whose phenotype consists of growth and mental retardation, seizures, minor dysmorphic features, café-au-lait spots and retinal flecks. This classification of ring 17 into two distinct groups based on the size of the deletion and the phenotypic manifestations should facilitate clinical suspicion of this rare chromosomal abnormality.
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Affiliation(s)
- V Shashi
- Department of Pediatrics/Medical Genetics, Wake Forest University School of Medicine, Winston-Salem, NC 27157, USA.
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10
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Speevak MD, Smart C, Unwin L, Bell M, Farrell SA. Molecular characterization of an inherited ring (19) demonstrating ring opening. Am J Med Genet A 2003; 121A:141-5. [PMID: 12910493 DOI: 10.1002/ajmg.a.20184] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Ring chromosomes arise following breakage in both chromosome arms and rejoining of the centric segment at the broken ends or by end-to-end fusion of the telomeres. The phenotype of ring carriers is unpredictable, and developmental abnormalities may occur even when the ring appears to be structurally balanced. This is believed to be due to mitotic instability from abnormal segregation and sister chromatid exchange in somatic cells. Although ring chromosomes usually arise as de novo events, transmittal from mosaic carriers to offspring sometimes occurs. In such cases, offspring with ring mosaicism in combination with a normal cell line remain unexplained. In this report, we used detailed molecular and cytogenetic analyses of a prenatally detected, inherited ring (19) to observe the behavior of the ring chromosome in culture, and to investigate the mechanism of inherited ring chromosome mosaicism.
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Affiliation(s)
- Marsha D Speevak
- Division of Genetics, Department of Laboratory Medicine, The Credit Valley Hospital, Mississauga, Ontario, Canada.
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11
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Parmar RC, Muranjan MN, Kotvaliwale S, Sharma S, Bharucha BA. Ring chromosome 12 with variable phenotypic features: clinical report and review of the literature. Am J Med Genet A 2003; 117A:275-7. [PMID: 12599192 DOI: 10.1002/ajmg.a.10044] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
A ring chromosome 12 (p13; q24.33) was observed in all cells analyzed from peripheral blood lymphocytes of a 15-year-old female referred for academic difficulties and growth delay. In addition to clinical manifestations generally observed with ring chromosome 12 such as growth retardation, mental deficiency, microcephaly, the patient had bilateral pseudocamptodactyly of little fingers, mild hirsutism, exaggerated lumbar lordosis, and ostium secundum atrial septal defect (ASD). The clinical features of reported cases are analyzed. The only consistent features were growth retardation and mental deficiency. Breakpoint in all the cases has been at the telomeric region with minimal deletion of chromosomal material. An account of complex changes at mitosis and meiosis in ring chromosome has been given. Examination of 200 metaphases demonstrated 2% cell line was showing 45,XX, -12. Serum lactate dehydrogenase (LDH) level was normal ruling out overlapping monosomy 12 syndrome.
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Affiliation(s)
- Ramesh C Parmar
- The Genetics Division, Department of Pediatrics, Seth G. S. Medical College and K. E. M. Hospital, Parel, Mumbai 400 055, India.
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12
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Doray B, Becmeur F, Girard-Lemaire F, Schluth C, Flori E. Esophageal and duodenal atresia in a girl with a 12q24.3-qter deletion. Clin Genet 2002; 61:468-71. [PMID: 12121357 DOI: 10.1034/j.1399-0004.2002.610613.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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13
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Mohamed AN, Ebrahim SA, Aatre R, Qureshi F, Jacques SM, Evans MI. Prenatal diagnosis of a de novo ring chromosome 11. AMERICAN JOURNAL OF MEDICAL GENETICS 2001; 102:368-71. [PMID: 11503165 DOI: 10.1002/ajmg.1492] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Ring chromosomes are uncommon findings in prenatal diagnosis. Growth retardation is the most significant manifestation, in particular among patients with rings of larger chromosomes. A 30-year-old gravida 1, para 0 white woman was referred for genetic counseling because of maternal anxiety. Cytogenetic analysis of amniotic fluid cells at 16 weeks gestation revealed an abnormal mosaic female chromosome complement; 46,XX,r(11)(p15q25)[14]/45,XX,-11[7]. The ring 11 showed no detectable loss of chromosomal material at 450 band level. Both parents had a normal karyotype. Fluorescence in situ hybridization demonstrated intact subtelomeric regions in the ring chromosome. A targeted ultrasound evaluation at the time of consultation suggested no significant abnormalities. The parents were counseled and subsequently decided to terminate the pregnancy. The autopsy revealed an immature female fetus with abnormal craniofacial features including brachycephaly, low-set ears and hypertelorism, bicornuate uterus, and calcifications in the renal tubules. The abnormal phenotypes could be a consequence of the ring instability, submicroscopic deletion, and/or alteration of genetic material at the site of fusion.
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Affiliation(s)
- A N Mohamed
- Department of Pathology/Cytogenetics Laboratory, Wayne State University, 4727 St. Antoine Blvd., Detroit, MI 48301, USA.
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14
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Sigurdardottir S, Goodman BK, Rutberg J, Thomas GH, Jabs EW, Geraghty MT. Clinical, cytogenetic, and fluorescence in situ hybridization findings in two cases of "complete ring" syndrome. AMERICAN JOURNAL OF MEDICAL GENETICS 1999; 87:384-90. [PMID: 10594875 DOI: 10.1002/(sici)1096-8628(19991222)87:5<384::aid-ajmg3>3.0.co;2-r] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The term "ring syndrome" was proposed to describe a phenotype of growth failure without major malformations due to a ring autosome. The growth failure is thought to be caused by instability of the ring chromosome leading to aneusomy and cell death. Most previous studies of ring chromosomes were based on standard cytogenetic banding techniques and were limited to microscopically detectable deletions in the ring chromosomes. We report on two patients with complete ring (4) and ring (9) chromosomes, respectively. The first was a 15-month-old girl and the second was a 16-month-old boy. They both presented with severe, symmetrical growth failure and normal psychomotor development in the absence of malformations. Their parents had a normal phenotype. The first case had a whorled pattern of hyperpigmentation and hypopigmentation on part of the face and chest, and the second case had a patchy hyperpigmented rash on the trunk. Peripheral blood karyotype of the first patient was 46,XX, r(4)(p16.3q35.2) and of the second 45,XY,-9/46,XY,r(9)(p24q34.3). G-band analysis suggested no loss of material in the ring chromosomes. These findings were confirmed by fluorescence in situ hybridization (FISH) analysis using chromosome-specific subtelomeric probes. The common human telomeric sequences were intact in the first patient but absent in the second patient. The cytogenetic and FISH data in our two cases provide further evidence for the existence of a "complete ring" phenotype independent of the autosome involved. Pigmentary skin changes are a useful clinical sign of mosaicism caused by the ring instability.
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Affiliation(s)
- S Sigurdardottir
- Kennedy Krieger Institute, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21287-4922, USA
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15
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Abstract
Côté et al. [1981: Ann Genet 24:231-235] suggested that ring chromosomes without a preceding deletion share a common pattern of phenotypic anomalies, independent of what chromosome is involved. The phenotype of such a "general ring syndrome" consists of growth failure without malformations, few or no minor anomalies, and mild-to-moderate mental retardation. We report on a patient with a ring 2 chromosome with features suggestive of Silver-Russell syndrome at birth and striking postnatal growth retardation with minor intellectual involvement supporting Côté's suggestion. This would be the ninth case of ring 2 chromosome published; the patient is the longest reported survivor, with a 10-year follow-up.
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Affiliation(s)
- Y Lacassie
- Department of Pediatrics, Louisiana State University Medical Center, New Orleans 70112-2822, USA.
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16
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Sathya P, Tomkins DJ, Freeman V, Paes B, Nowaczyk MJ. De novo deletion 12q: report of a patient with 12q24.31q24.33 deletion. AMERICAN JOURNAL OF MEDICAL GENETICS 1999; 84:116-9. [PMID: 10323735 DOI: 10.1002/(sici)1096-8628(19990521)84:2<116::aid-ajmg6>3.0.co;2-3] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
We report on a patient with de novo interstitial deletion of the long arm of chromosome 12: 46,XY,del(12)(q24.31q24.33). To our knowledge this is the first patient with this chromosomal abnormality reported. He was born with minor anomalies, ambiguous genitalia, tracheomalacia, and he was developmentally delayed at age 9 months. The phenotype associated with this deletion may be characteristic. However, because of the absence of reported cases of other patients with loss of this chromosomal region, we cannot delineate the specific phenotype further. Ambiguous genitalia or hypogonadism has been reported in other patients with chromosomal rearrangements involving 12q24.
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Affiliation(s)
- P Sathya
- Department of Pediatrics, Hamilton Health Sciences, Corporation and McMaster University, Ontario, Canada
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17
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Canevini MP, Sgro V, Zuffardi O, Canger R, Carrozzo R, Rossi E, Ledbetter D, Minicucci F, Vignoli A, Piazzini A, Guidolin L, Saltarelli A, dalla Bernardina B. Chromosome 20 ring: a chromosomal disorder associated with a particular electroclinical pattern. Epilepsia 1998; 39:942-51. [PMID: 9738673 DOI: 10.1111/j.1528-1157.1998.tb01443.x] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
PURPOSE The chromosome 20 ring [r(20)] is a rare chromosomal disorder without clear phenotypical markers. We describe the electroclinical pattern in a group of patients with r(20). METHODS We observed 3 patients (a boy, patient 1; his mother, patient 2; and an unrelated man, patient 3), performing prolonged video-EEG and cytogenetic studies and fluorescent in situ hybridization (FISH) with chromosome-specific telomeric probes. RESULTS All 3 patients had a very similar abnormal electroclinical pattern characterized by long bursts or trains of rhythmic theta waves, which were sharply contoured or had a notched appearance (with no detectable clinical correlate), and generalized spike waves (SW) associated with seizures of probable frontotemporal origin (SFT). In all 3 patients, the cytogenetic analysis of T lymphocytes showed mosaicism with a normal cell line and a second cell line with a chromosome 20, although the latter was little represented in patients 2 and 3. A few cells with a single chromosome 20 were also found. The same cytogenetic findings were confirmed in the lymphoblastoid cell line of patient 1 and in the fibroblasts of patient 3. FISH with chromosome-specific telomeric probes and TTAGGG sequences demonstrated the integrity of the ring chromosomes. CONCLUSIONS The clinical picture of these patients appears to be related to the instability of the r(20)-generating cells monosomic for chromosome 20 and is thus haploinsufficient for a gene. In these patients, the electroclinical pattern of theta waves (probably unrelated to epilepsy) and the SW and SFT, even with mild mental retardation (MR) or no MR and without dysmorphic features, suggest that the r(20) syndrome may be present.
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Affiliation(s)
- M P Canevini
- Centro Regionale Epilessia, Ospedale San Paolo, Università degli Studi, Milan, Italy
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18
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Page SL, Shaffer LG. Chromosome stability is maintained by short intercentromeric distance in functionally dicentric human Robertsonian translocations. Chromosome Res 1998; 6:115-22. [PMID: 9543014 DOI: 10.1023/a:1009286929145] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
While the formation of a dicentric chromosome often leads to chromosome instability, human dicentric Robertsonian translocations usually remain stable. To investigate the basis for this stability, we have examined the centromeres of 15 structurally dicentric rob(13q14q) Robertsonian translocations using immunofluorescence and fluorescence in situ hybridization (FISH). The immunofluorescence detection of centromere protein C (CENP-C) was used as a marker for centromere function as CENP-C seems to play an essential role in kinetochore structure and stability and was previously shown to be absent from inactive centromeres. In all 15 translocation-containing cell lines, CENP-C was confined to only one of the centromeres of the translocation in a fraction of the cells analyzed. This suggests that centromere inactivation commonly occurs on dicentric Robertsonian translocations and may serve as one mechanism allowing for their stability. However, in the majority of the translocations (12 out of 15), a portion of the cells analyzed displayed CENP-C immunofluorescence at both centromeres, suggesting that both centromeres were active and that the translocation was functionally dicentric. The percentage of cells with CENP-C at both centromeres ranged from 2% to 82%. These results support the hypothesis that the close proximity of two functional centromeres on Robertsonian translocations allows them to remain stable.
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Affiliation(s)
- S L Page
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
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19
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Conte RA, Kleyman SM, Kharode C, Verma RS. Delineation of a ring chromosome 16 by the FISH-technique: a case report with review. Clin Genet 1997; 51:196-9. [PMID: 9137886 DOI: 10.1111/j.1399-0004.1997.tb02452.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
We report on a new case with ring chromosome 16. Initially, the cytogenetic findings with GTG-banding revealed a 46,XY,r(16)(::p13.3-->q24::)/46,XY karyotype. This is the first case of r(16) co-existing with a normal cell line with minimal clinical consequences. The ring appeared to be monocentric and stable. A ring chromosome can result in a loss of varied segments of one or both chromosome arms or may involve telomere-telomere fusion without loss of genetic material. Thus it was imperative to use the latest molecular cytogenetic techniques for evaluation of this ring chromosome. It is believed that the ring chromosome retained specific telomeric sequences unique to 16q and that there was no loss of genetic material during the ring formation. Apparently, either a 16p telomere-16q telomere fusion or a fusion between the 16q telomere and a distal segment of the 16p13 band may explain the mechanism of ring formation. In either case, loss of genetic material is assumed to be negligible. A more descriptive karyotype of the proband was determined to be: 46,XY,r(16)(::pter or ::p13.3-->qter::)/46,XY. The fluorescent in-situ hybridization technique using various DNA probes provided this finer characterization.
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Affiliation(s)
- R A Conte
- Division of Genetics, Stanley S. Lamm Institute for Child Neurology and Developmental Medicine, Long Island College Hospital-SUNY Health Science Center, at Brooklyn, USA
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20
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Abstract
A new case of ring chromosome 9 in a 36-month-old child is presented. In addition to the pathognomonic features of this rare disorder (only 21 cases reported), our patient presents some peculiarities, such as corpus callosum hypoplasia and epileptic seizures (infantile periodic spasms). We also observed a reduced level of leukocyte interferon alpha whose synthesis is controlled by a gene on chromosome 9 and which could be responsible for the recurrent respiratory tract infections, typical and sometimes fatal in these patients.
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Affiliation(s)
- G Lanzi
- Department of Child Neuropsychiatry, C. Mondino Foundation, Neurological Institute IRCCS, University of Pavia, Italy
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21
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Casati A, Riboni R, Caprioli J, Nuzzo F, Mondello C. Condensation anomalies and exclusion in micronuclei of rearranged chromosomes in human fibroblasts cultured in vitro. Chromosoma 1995; 104:137-42. [PMID: 8585991 DOI: 10.1007/bf00347696] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Anomalies of chromatin condensation, such as fragmentation, uncoiling and pulverization, were observed in XP9UV25, a xeroderma pigmentosum fibroblast clone in which a high proportion of cells carried an end-to-end dicentric chromosome, dic (5;16) (p15.2;q24), that gives rise during propagation in culture to a variety of dicentric and monocentric derivatives. The coiling anomaly affected exclusively part of a rearranged chromosome, in particular the region previously involved in breakage events. The heterochromatic 16q region, which is a preferential breakpoint in the formation of dicentric and monocentric derivatives, was consistently the limit of the uncoiled or pulverized regions. This observation suggests that the anomalous chromatin behavior could derive from alteration of a region relevant for the correct condensation of the chromosome. In XP9UV25 the frequency of nuclei with associated micronuclei increased with time in culture, in parallel with that of mitoses with dicentric chromosomes. In situ hybridization with DNA probes specific for chromosomes 5 and 16 revealed hybridization signals in about 40% of micronuclei. Since the frequency of micronuclei is about ten times less than that of dicentrics, it is probable that only the rearranged chromosomes undergoing coiling anomalies are excluded in micronuclei.
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Affiliation(s)
- A Casati
- Istituto di Genetica Biochimica ed Evoluzionistica del C.N.R., via Abbiategrasso 207, I-27100 Pavia, Italy
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22
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Sullivan BA, Wolff DJ, Schwartz S. Analysis of centromeric activity in Robertsonian translocations: implications for a functional acrocentric hierarchy. Chromosoma 1994; 103:459-67. [PMID: 7720412 DOI: 10.1007/bf00337384] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Approximately 90% of human Robertsonian translocations occur between nonhomologous acrocentric chromosomes, producing dicentric elements which are stable in meiosis and mitosis, implying that one centromere is functionally inactivated or suppressed. To determine if this suppression is random, centromeric activity in 48 human dicentric Robertsonian translocations was assigned by assessment of the primary constrictions using dual color fluorescence in situ hybridization (FISH). Preferential activity/constriction of one centromere was observed in all except three different rearrangements. The activity is meiotically stable since intrafamilial consistency of a preferentially active centromere existed in members of six families. These results support evidence for nonrandom centromeric activity in humans and, more importantly, suggest a functional hierarchy in Robertsonian translocations with the chromosome 14 centromere most often active and the chromosome 15 centromere least often active.
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MESH Headings
- Amniocentesis
- Cells, Cultured
- Centromere/metabolism
- Centromere/ultrastructure
- Child
- Chorionic Villi Sampling
- Chromosome Aberrations/diagnosis
- Chromosome Aberrations/embryology
- Chromosome Aberrations/genetics
- Chromosome Disorders
- Chromosomes, Human/metabolism
- Chromosomes, Human/ultrastructure
- Chromosomes, Human, Pair 14/metabolism
- Chromosomes, Human, Pair 14/ultrastructure
- Chromosomes, Human, Pair 15/metabolism
- Chromosomes, Human, Pair 15/ultrastructure
- Female
- Humans
- In Situ Hybridization, Fluorescence
- Lymphocytes/ultrastructure
- Meiosis
- Pregnancy
- Single-Blind Method
- Translocation, Genetic
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Affiliation(s)
- B A Sullivan
- Department of Genetics, Case Western Reserve University and University Hospitals, Cleveland, OH 44106
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23
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Migliori MV, Cherubini V, Bartolotta E, Pettinari A, Pecora R. Ring chromosome 5 associated with severe growth retardation as the sole major physical abnormality. AMERICAN JOURNAL OF MEDICAL GENETICS 1994; 49:108-10. [PMID: 8172236 DOI: 10.1002/ajmg.1320490121] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
We report on a case of ring chromosome 5 in a 36-month-old girl with severe growth retardation, clinodactyly, mild psychological abnormalities, and normal facial appearance. Endocrine tests showed partial growth hormone deficiency. Cytogenetic investigation failed to demonstrate any apparent microscopic deletion of either short or long arm of chromosome 5 as consequence of ring formation. In 12% of cells examined, the ring was either absent or present in multiple copies. Only 3 previous cases of ring chromosome 5 have been reported in association with short stature of prenatal onset and minor anomalies, without mental retardation.
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Affiliation(s)
- M V Migliori
- Laboratorio di Citogenetica, Ospedale Salesi, Ancona, Italy
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24
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Pezzolo A, Gimelli G, Cohen A, Lavaggetto A, Romano C, Fogu G, Zuffardi O. Presence of telomeric and subtelomeric sequences at the fusion points of ring chromosomes indicates that the ring syndrome is caused by ring instability. Hum Genet 1993; 92:23-7. [PMID: 8365723 DOI: 10.1007/bf00216140] [Citation(s) in RCA: 59] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
In situ hybridization of a telomeric (TTA-GGG)n sequence to metaphases from three cases of ring chromosome, involving respectively chromosomes 4, 16, and 20, showed the presence of the cognate sequences in all three rings. To investigate whether these ring chromosomes originated by telomere-telomere fusion, we determined, by in situ hybridization, whether telomere-associated sequences and/or specific distal sequences were still present in the ring chromosomes. The finding that these sequences were preserved in all the ring chromosomes strongly indicates that they originated by telomere-telomere fusion. All three subjects carrying the ring chromosomes are affected by the so-called ring syndrome, with failure to thrive, minor dysmorphic signs and no major anomalies. The r(4) patient has the ring in mosaic form with a normal cell line and has normal intelligence. The r(16) and the r(20) patients have moderate mental retardation and suffer from seizures. We conclude that the ring syndrome, even in its more severe manifestation, is caused by ring chromosome instability.
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Affiliation(s)
- A Pezzolo
- Laboratorio di Citogenetica-Istituto G. Gaslini, Genova, Italy
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25
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Abstract
We report on an 8-year-old boy exhibiting microcephaly, clinodactyly and growth retardation. Chromosome analysis showed a ring chromosome 4 in 97% of the cells and a high number of hyperploid cells with various ring formations. The breakpoints are presumed to be close to or in the telomeric regions of both arms. The patients reported with ring chromosome 4 and breakpoints close to the telomeres of both arms showed unspecific, mild clinical findings with normal or retarded mental development. These signs are probably related to the continuous generation of aneuploid cells.
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Affiliation(s)
- G Freyberger
- Department of Human Genetics, University of Wuerzburg, Federal Republic of Germany
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26
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Rivera H, Zuffardi O, Gargantini L. Nonreciprocal and jumping translocations of 15q1----qter in Prader-Willi syndrome. AMERICAN JOURNAL OF MEDICAL GENETICS 1990; 37:311-7. [PMID: 2260556 DOI: 10.1002/ajmg.1320370304] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
We analyzed 33 cases of Prader-Willi syndrome (PWS) (including 2 personal observations) with translocations of 15q1----qter onto the terminals of different, apparently whole chromosomes. In all but one of the 23 informative cases the translocations was de novo. Thirty of the patients were unbalanced and 27 had a 45-chromosome constitution compatible with a 3:1 segregation. One balanced and 2 unbalanced translocations were jumping ones. The possible existence of actual non-reciprocal translocations in man is indicated by the following considerations about these and other PWS-associated rearrangements: 1) The observed excess of de novo translocations; 2) the relatively frequent familial occurrence of reciprocal 15q translocations; 3) the concurrence in 3 terminal translocation cases of an idic (15); 4) the visualization of jumping terminal translocations as simple transpositions rather than as successive reciprocal exchanges; 5) the predominance of true isodicentrics in PWS patients with extra inv dup(15) chromosomes; and 6) the rarity of extra derivatives resulting in 15q proximal tertiary trisomy. Additional findings in the present series were normal parental age in the de novo 45-chromosome cases, an apparently random distribution of telomeric breakpoints, and the occurrence of different breakpoints within the 15q1 region.
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Affiliation(s)
- H Rivera
- Istituto di Biologia Generale e Genetica Medica, Università di Pavia, Italy
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27
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Baroncini A, Avellini C, Neri C, Forabosco A. Distal 12p deletion in a stillborn infant. AMERICAN JOURNAL OF MEDICAL GENETICS 1990; 36:358-60. [PMID: 2363438 DOI: 10.1002/ajmg.1320360324] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
A stillborn female with a "de novo" deletion of band 12p13 is described. Her main clinical manifestations are intrauterine growth retardation, unilateral cleft lip, protruding tongue, and small, low set, and posteriorly angulated ears. Comparison of this case with 4 previous reported patients with an isolated distal del(12p) fails to show significant common phenotypic characteristics.
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Affiliation(s)
- A Baroncini
- Chair of Histology and General Embryology, University of Modena, Italy
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28
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Abstract
Ring (20) chromosomal mosaicism defined by two cell lines (one normal and the other with the ring) has been demonstrated in lymphocyte and fibroblast cultures from three members of a family through two generations. Two carriers of the ring chromosome were affected and showed the typical signs of r(20) syndrome including mental retardation, microcephaly, behavioral disorders, and epilepsy. The epilepsy is characterized by complex partial seizures sometimes evolving secondarily into generalized tonic-clonic seizures and is poorly controlled by or resistant to medical treatment. The mother of the two patients, also a carrier of ring (20) chromosomal mosaicism, was clinically and phenotypically normal and did not exhibit any signs of epilepsy. Lymphocyte and fibroblast cultures from the most severely affected sib, the proband, contained the highest percentage of cells with ring (20) chromosome and revealed the greatest instability of the ring. Though it is assumed that the ring (20) chromosome arose from terminal breakage and reunion in both arms, no loss of genetic material could be documented cytogenetically. Yet the question arises of how ring chromosomal mosaicism can be passed on. One explanation might be that a chromosome 20 predisposed to terminal lesions or breaks is transmitted from the mother to her offspring. Inherited instability of this type might lead to de novo formation of the ring.
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Affiliation(s)
- E Back
- Institut für Humangenetik und Anthropologie Universität, Freiburg, Federal Republic of Germany
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29
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Park JP, Graham JM, Andrews PA, Wurster-Hill DH. Ring chromosome 12. AMERICAN JOURNAL OF MEDICAL GENETICS 1988; 29:437-40. [PMID: 3354616 DOI: 10.1002/ajmg.1320290228] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
A ring chromosome 12 (p13.3q24.3) was observed in all cells analyzed from skin fibroblasts and the peripheral blood of a 19-year-old man initially referred for developmental delay with expressive language deficiency. Other phenotypic anomalies included growth deficiency, multiple café-au-lait spots, mild pectus excavatum, glandular hypospadias, left esotropia, clinodactyly of the fifth fingers, and hypothyroidism with elevated antithyroid antibodies. The four previously reported cases of r(12) support the theory of a general ring phenotype which is manifested independently of the specific autosome involved and which is characterized by growth failure, moderate mental retardation, and lack of other major phenotypic anomalies. Breakpoints in all cases of r(12) have been assigned to the telomeric regions, suggesting minimal deletion of chromosome material.
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Affiliation(s)
- J P Park
- Department of Pathology, Dartmouth-Hitchcock Medical Center, Hanover, New Hampshire
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30
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Kosztolányi G. Decreased cell viability of fibroblasts from two patients with a ring chromosome: an in vitro reflection of growth failure? AMERICAN JOURNAL OF MEDICAL GENETICS 1987; 28:181-4. [PMID: 3674110 DOI: 10.1002/ajmg.1320280125] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
We found decreased cell viability in fibroblast cultures from two patients, one with ring chromosome 4, the other with ring chromosome 15, who had severe somatic retardation. Cell viability was studied with the trypan blue exclusion assay, and in comparison with matched control cells was found to be 72.0 vs. 93.1%, and 79.8 vs 90.2%, respectively. Cloning efficiency of fibroblasts from the patient with ring chromosome 15 was also decreased (12.3 vs. 25.7%). It is suggested that the decreased cell viability is due to a continuous production of hypomodal cells, a process related to the ring structure per se, and perhaps responsible for the severe somatic retardation frequently observed in patients with a ring chromosome.
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Affiliation(s)
- G Kosztolányi
- Department of Pediatrics, University Medical School, Pécs, Hungary
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31
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Kosztolányi G. Does "ring syndrome" exist? An analysis of 207 case reports on patients with a ring autosome. Hum Genet 1987; 75:174-9. [PMID: 3817812 DOI: 10.1007/bf00591082] [Citation(s) in RCA: 174] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Analysis of 207 case reports on patients with ring autosome showed that: Forty patients, a fifth of the total, had extreme growth failure together with an otherwise almost-normal appearance, viz. no major malformation, no specific deletion syndrome, no or only a few unspecific minor anomalies. This phenotype may be regarded as the "ring syndrome", a term proposed by Cote et al. (1981) since it is independent of what chromosome is involved. Severe growth failure, the sole major physical abnormality in the "ring syndrome", was seen significantly more often among patients with ring of larger chromosomes than among patients with a smaller ring, indicating that the greater the chromosome involved in ring formation, the higher is the probability of severe growth failure. Larger ring chromosomes showed significantly more often instability than smaller rings, suggesting that there may be a correlation between ring instability and the size of the chromosome involved. Growth failure was present in significantly more patients with a "labile" ring than with a "stable" ring, indicating that a correlation may exist between ring instability and growth failure. It is suggested that the "ring syndrome" observed in many cases with ring autosome may result from end-to-end fusion of chromosome ends, an event not involving deletion in the genetic sense. It is also suggested that the "ring syndrome" is caused by a continuous generation of secondary aneuploid cells with increased mortality, i.e. structural ring instability which seems to be a function of the size of the chromosome involved. Thus, formation of a ring chromosome in certain cases might be regarded as a "structural mutation", i.e. an alteration in the structure of the genetic material per se, rather than a loss or gain of genetic dosages.
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32
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Orye E, Craen M, Laureys G, van Coster R, van Mele B. Extra Yq and partial monosomy 12p due to a Y;12 translocation in a boy with features of the 12p deletion syndrome. J Med Genet 1985; 22:222-4. [PMID: 4009644 PMCID: PMC1049428 DOI: 10.1136/jmg.22.3.222] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
A Y;12 translocation, resulting in extra Yq material and partial monosomy 12p, was found in a 7 1/2 year old boy. He showed growth and mental retardation and several of the congenital anomalies seen in the 12p deletion syndrome. LDHB activity, the gene for which is located at 12p12, was normal in serum, in accordance with the suspected 12p13 deletion in the patient.
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33
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Kitatani M, Takahashi H, Yasuda J, Chen CC, Ida F, Shike S. A case of ring chromosome 3, 46,XX,-3,+r(3)(p26q29). JINRUI IDENGAKU ZASSHI. THE JAPANESE JOURNAL OF HUMAN GENETICS 1984; 29:157-62. [PMID: 6513151 DOI: 10.1007/bf01873537] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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34
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Vig BK. Sequence of centromere separation: orderly separation of multicentric chromosomes in mouse L cells. Chromosoma 1984; 90:39-45. [PMID: 6205831 DOI: 10.1007/bf00352276] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Mouse L cells have many dicentric chromosomes and one with eight centromeres. All eight centromeres behave similarly until midmetaphase when most centromeres split into two units each in apparently quick succession but out-of-phase. This premature separation leaves one or perhaps two closely located centromeres intact, which separate at late metaphase-anaphase, drawing the two chromatids to opposite poles. Such dominance of one centromere over all others, though unexplained, ensures the lack of any mitotic abnormality such as bridges or fragments. These observations show that all the centromeres are retained as functional primary constrictions except for a change in functional regulation when more than one centromere are located on a chromosome.
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35
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Vig BK. Sequence of centromere separation another mechanism for the origin of nondisjunction. Hum Genet 1984; 66:239-43. [PMID: 6232200 DOI: 10.1007/bf00286609] [Citation(s) in RCA: 33] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The most commonly accepted view about the origin of aneuploidy is that it is due to errors in meiotic division. However, its rare occurrence makes it difficult to explain recurrent births of trisomic children to some parents. This problem causes more serious concern when one accepts that an abnormal (n + 1 or n - 1) sperm would enter fertilization by overriding thousands, or even millions, of normal haploid sperms. Also, the failure of aneuploidy to be induced in the offspring of mammals treated with mutagens raises questions about the effectiveness of the accepted mode of origin of errors. Current concepts also do not explain why one observes more errors of meiotic I, than of meiotic II, origin. It is known that most chromosomes separating at meta-anaphase junction in mitosis follow a nonrandom, genetically controlled sequence of separation. The present proposal makes use of out-of-phase separation of a rare chromosome, like premature separation in mitosis of the X in elderly humans or of an 18 in parents of trisomy 18 children. The suggestion is made that such out-of-phase separation results in aneuploid cell lines by total failure of the centromere to separate or by it separating too early, before the spindle is formed. The prematurely separating centromeres, it appears, do not attach to spindle fibers and hence cause nondisjunction. Such nondisjunction in embryonic stages will produce apparently normal individuals with mosaicism in somatic and/or gametic tissue. An individual carrying mosaicism in gonadal tissue will produce a large number of abnormal gametes, one of which may have a reasonable chance of entering fertilization. This mode of origin of aneuploidy takes care of all questions raised above and finds support in the data available in the literature. Several of the suggestions made in the hypothesis are easily testable.
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36
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Schwartz S, Palmer CG, Weaver DD, Priest J. Dicentric chromosome 13 and centromere inactivation. Hum Genet 1983; 63:332-7. [PMID: 6862437 DOI: 10.1007/bf00274757] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The karyotype of a child with dysmorphic findings suggestive of both trisomy 13 and the 13q--syndrome was found to have cells with one of two different dicentric chromosomes: one bearing a duplication of chromosome 13q [46,XX,-13, + psu dic (13)t(13;13)(pter leads to cen leads to q34::q34 leads to pter)] and the other a deletion of 13q [46,XX,-13, + psu dic (13)t(13;13)(pter leads to cen leads to q22::q11 leads to pter]. Longitudinal cytogenetic studies in leukocytes demonstrated a loss of those cells possessing the small dicentric [psu dic(13)(q22;q11)], whereas fibroblasts from two separate skin biopsies contained only this marker. Q-band polymorphisms indicated that both dicentrics were of paternal origin, with the smaller dicentric derived from the larger via the bridge-breakage-fusion cycle. The presence of two active centromeres could not be confirmed in either dicentric.
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37
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Abstract
A study of the ring chromosome 13 syndrome is presented with detailed clinical and cytogenetic features of three new unrelated cases. The clinical limits of this syndrome can now be defined. An analysis of these cases together with those in the literature indicates that the syndrome forms a continuous spectrum, and no further taxonomic subdivision is possible at this stage of knowledge. The chromosome breakpoints in the first two cases are 13p11 and 13q32 and in the third case 13p11 and 13q33 or 13q34. All described cases of the ring 13 syndrome have breakpoints within the region bounded by bands 13q21 to 13q34. All rings are negative for silver banding. Peripheral blood cultures showed an average of 88% of metaphases to be 46,XX,r(13), with the remaining 12% manifesting either random loss or ring duplication. The rings vary in size and show a variable number of centromeres. An estimate of the birth incidence of this condition in the Anglo-Saxon population is 1 in 58,000. Parents of affected children are clinically and cytogenetically normal, the rings in affected offspring being meiotic in origin.
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38
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Pasquali F, Panarello C, Bernasconi P, Casalone R. The isochromosome (17q) in chronic myelocytic leukaemia: mechanism of origin, centromeric function and clonal evolution. Hum Genet 1982; 62:89-90. [PMID: 6961099 DOI: 10.1007/bf00295610] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
An isochromosome (17q) may be observed in myelo- and lymphoproliferative disorders, as well as in solid tumours and it is very frequent in Ph1-positive chronic myelocytic leukaemia (CML) during the blastic phase. A study on the mechanism of origin and on the centromeric function of the i(17q)s was performed by means of the C- and Cd-staining techniques in four CML patients. In all these cases, as well as in four others reported in the literature, the i(17q) is dicentric thus indicating that its origin is due to a break on the short arms followed by joining of the two chromatids containing the centromere. The Cd-technique indicates that one of the two centromeres is inactive: this result is consistent with the fact that the i(17q) in CML is a step in the clonal evolution towards the acute phase.
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