Showing papers on "Ring chromosome published in 1989"
TL;DR: This procedure provides a novel approach for scoring these complex chromosome aberrations, particularly damage induced by radiation or radiomimetic agents, such as dicentrics and multicentrics.
56 citations
TL;DR: The structural rearrangements of a chromosome 21 that led to the de novo formation of a human ring chromosome 21 were characterized and molecular cloning and chromosomal localization of the DNA regions flanking the ring junction provide evidence for a long arm to long arm fusion in formation of the r(21).
Abstract: We have characterized the structural rearrangements of a chromosome 21 that led to the de novo formation of a human ring chromosome 21 [r(21)]. Molecular cloning and chromosomal localization of the DNA regions flanking the ring junction provide evidence for a long arm to long arm fusion in formation of the r(21). In addition, the centromere and proximal long arm region of a maternal chromosome 21 are duplicated in the r(21). Therefore, the mechanism in formation of the r(21) was complex involving two sequential chromosomal rearrangements. (i) Duplication of the centromere and long arm of one maternal chromosome 21 occurred forming a rearranged intermediate. (ii) Chromosomal breaks in both the proximal and telomeric long arm regions on opposite arms of this rearranged chromosome occurred with subsequent reunion producing the r(21).
44 citations
TL;DR: A stillborn male infant with a ring chromosome 15 and some features compatible with Fryns' syndrome is presented and neither diagnosis is common and the overlap may be of significance.
Abstract: A stillborn male infant with a ring chromosome 15 and some features compatible with Fryns' syndrome is presented. Neither diagnosis is common and the overlap may be of significance.
40 citations
TL;DR: 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 and the question arises of how ring chromosomal mosaicism can be passed on.
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.
39 citations
TL;DR: This is the first cytogenetic description, with banding techniques, of a malignant meningioma, from a patient submitted to two surgeries separated by 1 year, and it is reported that there was a recurrent trisomy of chromosome 3.
38 citations
TL;DR: The three-dimensional organization of polytene chromosomes within nuclei containing rearranged X chromosomes was examined in male Drosophila melanogaster, finding that for both genotypes the three- dimensional behavior at each euchromatic locus is independent of the orientation of the chromosome on which it resides.
Abstract: The three-dimensional organization of polytene chromosomes within nuclei containing rearranged X chromosomes was examined in male Drosophila melanogaster. Salivary glands of third instar larvae containing either an inverted X chromosome (YSX.YL, In(1)EN/O) or a ring X chromosome (R(1) 2/BSYy+) were fixed, embedded, and serially sectioned. The nuclei in contiguous groups of cells were modeled and analyzed. We find that for both genotypes the three-dimensional behavior at each euchromatic locus is independent of the orientation of the chromosome on which it resides, independent of the behavior of loci not closely linked to it, and not similar in neighboring cells. The preference for right-handed chromosome coiling noted in previous studies is shown to be independent of homologous pairing. However, a relation between the extent of chromosome curvature and the handedness of chromosome coiling is present only in homologously paired chromosomes. The attached-XY chromosome has two previously undescribed behaviors: a nearly invariant association of the euchromatic side of the proximal heterochromatin/euchromatin junction with the nucleolus and a frequent failure of this site to attach to the chromocenter. The relative chromosome arm positions are often similar in several neighboring cells. The size of these patches of cells, assuming that they represent clones, indicates that such arrangements are at best quasi-stable: they may be maintained over at least one, but less than four, cell divisions. The observed nuclear organization in salivary glands is inconsistent with the idea that position in the polytene nucleus plays a major role in the normal genetic regulation of euchromatic loci.
29 citations
TL;DR: A female child with a terminal deletion on the long arm of chromosome 14, 46,XX,del(14)(q31.1), presented with microcephaly, narrow palate, gingival hypertrophy, protuberant ears, and a small haemangioma on the back.
Abstract: A female child with a terminal deletion on the long arm of chromosome 14, 46,XX,del(14)(q31.1), presented with microcephaly, narrow palate, gingival hypertrophy, protuberant ears, and a small haemangioma on the back. She was mildly mentally retarded. Only a few patients with a partial deletion of 14q (14q-) have been reported without consistent clinical findings. Although a clinical syndrome associated with ring chromosome 14, r(14), has been established, no distinct pattern has been so far reported in 14q-.
27 citations
TL;DR: Comparative investigations suggest that more polyploidy occurs in callus cultures than in suspension cell cultures, and the presence of cytokinin (kinetin) in the culture medium may reduce the extent of karyotype change.
Abstract: Investigations have been carried out on karyotype change in both callus and suspension cell cultures of Haplopappus gracilis (2n=4). It has been found that polyploidization arises directly in culture to give up to six times the normal diploid chromosome number in some cultures. In polyploid cultures, both chromosome loss and chromosome rearrangements occur to give rise to aneuploid karyotypes displaying chromosomes which differ in morphology from the diploid set. Whole or partial chromosome loss has been observed in the form of lagging chromosomes and chromosome bridges at anaphase, and micronuclei, ring chromosomes and chromosome fragments at other stages in mitosis. C-banded preparations have confirmed the occurrence of chromosomal rearrangements. Comparative investigations suggest that (i) more polyploidy occurs in callus cultures than in suspension cell cultures, and (ii) the presence of cytokinin (kinetin) in the culture medium may reduce the extent of karyotype change.
20 citations
Journal Article•
TL;DR: A 4-year-old child with a ring 20 chromosome mosaicism, low grade developmental delay, and seizures is described.
Abstract: A 4-year-old child with a ring 20 chromosome mosaicism, low grade developmental delay, and seizures is described.
12 citations
TL;DR: Cytogenetic analysis was carried out in 100 tissue specimens from 88 patients with bladder cancer, finding various chromosomal abnormalities, numerical as well as structural, found.
8 citations
Journal Article•
TL;DR: The study shows that the 11q aberrations represent frequent structural chromosome rearrangements in MDS and is associated more frequently with 11q deletions as the sole abnormality.
Abstract: In a series of 121 consecutive patients with a myelodysplastic syndrome (MDS), studied in two laboratories, of which 87 (719%) had abnormal karyotypes, twelve had a structural abnormality of the long arm of chromosome 11 (138%) There were six deletions, one ring chromosome and five reciprocal translocations, all involving a chromosome band 11q23 Of these twelve patients, five had a refractory anemia (RA) and seven a refractory anemia with excess of blasts (RAEB) RA was associated more frequently with 11q deletions as the sole abnormality, while translocations or multiple chromosome abnormalities were commonly associated with RAEB The study shows that the 11q aberrations represent frequent structural chromosome rearrangements in MDS
TL;DR: Three patients with MEN IIA S belonging to the same family, which has five affected subjects in two generations, have been studied, and an extra ring chromosome in 3% of the cells in one of the affected subjects is identified.
Journal Article•
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TL;DR: The prenatal amniotic fluid of a 38-year-old woman asking genetic advice, primarily because of a cystic fibrosis burdening her first pregnancy, discovered this chromosomal anomaly and made the karyotype of both parents which showed that mother was a carrier of the same anomaly as observed in her unborn child.
Abstract: A case of a rare anomaly of the human karyotype--ring chromosome 21--is presented. By analysing the prenatal amniotic fluid of a 38-year-old woman asking genetic advice, primarily because of a cystic fibrosis burdening her first pregnancy, the authors discovered this chromosomal anomaly and made the karyotype of both parents which showed that mother was a carrier of the same anomaly as observed in her unborn child. The karyotyping of her second 7-year-old child also revealed ring chromosome 21, identical with that in its mother and unborn sister.
TL;DR: Results show that the order of these chromosome 14 markers is cen-PI-D14S1-IGH, in keeping with multipoint linkage data, and further molecular characterization of ring 14 chromosomes should lead to a detailed understanding of the molecular events and clinical consequences of the gene deletion associated with such chromosomal aberrations.
Abstract: Molecular characterization of a ring chromosome 14 was carried out in a patient with the 46,XX,r(14) karyotype. The breakpoints shown by chromosome banding were within bands p11 and q32. Using molecular probes for the immunoglobulin heavy chain (IGH), D14S1 and PI loci located at 14q32, we showed that the IGH and D14S1 loci, located at 14q32.2 and 14q32.2, respectively, were deleted on the ring chromosome 14, but that the PI locus was not. Therefore, the chromosomal break lies between PI and D14S1. These results show that the order of these chromosome 14 markers is cen-PI-D14S1-IGH, in keeping with multipoint linkage data. Further molecular characterization of ring 14 chromosomes should lead to a detailed understanding of the molecular events and clinical consequences of the gene deletion associated with such chromosomal aberrations.
TL;DR: ICR-170 (2methoxy-6-chloro-9-(3-(ethyl-2-2 chloro ethyl)-aminopropyl amino) acridine 2HCl)-a synthetic antitumor drug was assayed for HGPRT gene locus mutation, chromosomal aberrations and sister chromatid exchanges in V79 cells system as discussed by the authors.
Abstract: ICR-170(2-methoxy-6-chloro-9-(3-(ethyl-2-2 chloro ethyl)-aminopropyl amino) acridine 2HCl)-a synthetic antitumor drug was assayed for HGPRT gene locus mutation, chromosomal aberrations and sister chromatid exchanges in V79 cells system. The tested concentrations (0.1, 0.3, 1.0 and 3.0μg/ml) showed dose dependent effect. Chromosomal abnormalities were gap, break, fragment, ring chromosome, dicentric chromosome, exchange figures and endoreduplication. The present study suggests that ICR-170 is strong mutagenic, chromotoxic and supposed to be potentially carcinogenic compound.
Metz1
TL;DR: A proximal 19q duplication was observed in lymphocytes of a young boy with mental retardation, dysmorphism, but without visceral malformation.
Abstract: A proximal 19q duplication was observed in lymphocytes of a young boy with mental retardation, dysmorphism (weight excess, macrocephaly, downward slanted palpebral fissures, hypertelorism, broad nose, typical mouth), without visceral malformation. His mother had an interstitial deletion and ring chromosome derived from 19q.
TL;DR: In this article, two mutant alleles of the meiotic locus, mei-9, have been examined for their effect on magnification of a rod Xbb chromosome and transmission of a ring Xbb chromosomes under magnifying conditions.
Abstract: Two mutant alleles of the meiotic locus, mei-9, have been examined for their effect on magnification of a rod Xbb chromosome and transmission of a ring Xbb chromosome under magnifying conditions. Our results indicate that the effects of these two mutations are allele-specific: mei-9a strongly inhibits both rod chromosome magnification and ring chromosome loss under magnifying conditions, while mei-9b has a smaller inhibitory effect on rod chromosome magnification and on the transmission of ring chromosomes under magnifying conditions. These observations can be explained by a difference in leakiness between the two alleles. Our results demonstrate that mutants defective in excision repair and repair replication inhibit ribosomal gene magnification. This suggests that a component of the excision repair pathway is involved in the process of magnification.
Journal Article•
TL;DR: A chromosomal study was carried out on 10 cases of cat cry syndrome from 5,870 cases submitted to the Laboratory of Cytogenetics, National Taiwan University Hospital from Nov. 1968 through Apr. 1988, finding that laryngomalacia or underdevelopment of the larynx may be a factor causing the cat-like cry.