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Showing papers on "Ring chromosome published in 1983"


Journal ArticleDOI
TL;DR: It is proposed that monosomy of distal 17p may be the cause of Miller-Dieker syndrome in some patients because of abnormalities of chromosome 17 in two of three unrelated patients with this syndrome.

165 citations


Journal ArticleDOI
TL;DR: Chromosomes with homogeneously staining regions (HSR) were analysed in a subclone of the H4 rat hepatoma cell line, revealing that an HSR on the short arm of chromosome 3 became unstable and changed its position within the chromosome.
Abstract: Chromosomes with homogeneously staining regions (HSR) were analysed in a subclone of the H4 rat hepatoma cell line, where they represent amplification of the ribosomal RNA (rRNA) genes. Detailed G-band analysis of the subclone revealed that an HSR on the short arm of chromosome 3 became unstable and changed its position within the chromosome. The evolution of this marker chromosome was associated with the terminal deletion of the normal long arm of the HSR-bearing chromosome 3 and may have involved ring formation as a result of fusion between the HSR on the short arm and the broken end of the long arm. Evidence was obtained for breakage at different sites within the ring, producing chromosomes with HSRs located terminally on either the long arms or both arms. The terminally located HSR underwent elongation in some cells presumably as a result of a breakage-fusionbridge cycle characteristic of instability due to telomeric loss. It is suggested that terminally located HSRs may generally occur this way.

35 citations


Journal ArticleDOI
TL;DR: A 46,XX or XY,r(22) mosaicism was discovered in five patients of a family with a range of dysplastic features from mild and nonspecific withoutmental retardation to more distinctive with mental retardation.
Abstract: A 46,XX or XY,r(22) mosaicism was discovered in five patients of a family with a range of dysplastic features from mild and nonspecific without mental retardation to more distinctive with mental retardation. The 22 ring chromosome was segregating in three generations.

35 citations


Journal ArticleDOI
TL;DR: Clinically, these cases are quite variable, and a review of ten previously reported cases suggests difficulty of phenotype-karyotype correlation in patients with a ring 6.
Abstract: We present four children with a ring chromosome 6. Clinically, these cases are quite variable. A review of ten previously reported cases also suggests difficulty of phenotype-karyotype correlation in patients with a ring 6.

32 citations


Journal ArticleDOI
TL;DR: Cell populations were relatively homogenous and do not indicate any genetic instability as a result of hybridization between remote plant species, and species-specific multiple molecular forms of esterase and amylase from both parents were present in most cell clones.
Abstract: The genetic constitution of the cell hybrids Atropa belladonna + Nicotiana chinensis, obtained by cloning of individual heteroplasmic protoplast fusion products (Gleba et al. 1982) and cultured in vitro for 12 months, has been studied. The study comprised 11 hybrid cell clones of independent origin and included analysis of a) chromosome number, size, morphology, and relative position in metaphase plates, b) multiple molecular forms of the enzymes esterase and amylase, and c) relative nuclear DNA content. The data obtained permit us to conclude that, after one year of unorganized growth in vitro, the cells of most (8) clones had retained chromosomes of both parents, while species-specific elimination of nearly all Atropa chromosomes had occurred in three clones. About half of the non-segregating clones possess 120–150 chromosomes including 50–70 of Atropa and 50–90 of Nicotiana. Other clones are polyploid and possess 200–250 chromosomes with a predominance of either Atropa or Nicotiana chromosome types. Only a few chromosomal changes (reconstituted chromosomes, ring chromosomes) have been detected. In some metaphase plates, chromosomes of the two parents tend to group separately, indicating non-random arrangement of chromosomes of the two parents within the hybrid nucleus. Cytophotometric studies of the relative nuclear DNA content showed that distribution histograms for cell clones were similar to those of non-hybrid cultured cells. Cell populations were relatively homogenous and do not indicate any genetic instability as a result of hybridization between remote plant species. Biochemical analysis of isoenzyme patterns confirmed that in most cell clones, species-specific multiple molecular forms of esterase and amylase from both parents were present, i.e. genetic material of both parental species was expressed in the cell hybrids.

29 citations


Journal ArticleDOI
TL;DR: The in vivo effects of cis-platinum(II)diamminodichloride (cis-PDD) treatment on the induction of chromosome aberrations in Drosophila melanogaster germ cells are determined and mei-9 excision repair function is involved in the repair of cis -PDD-induced DNA lesions in a manner that provides additional evidence that partial and ring chromosome losses are not completely homologous.
Abstract: The authors have determined the in vivo effects of cis-platinum(II)diamminodichloride (cis-PDD) treatment on the induction of chromosome aberrations in Drosophila melanogaster germ cells. cis-PDD treatment induces significant increases in chromosome breakage in all stages of spermatogenesis in a battery of test systems using ring or rod-X males and repair-proficient or deficient females. Since no increase in nondisjunction was induced by cis-PDD in either male or female germ cells, any aneuploidy inducing effects of this compound should result from its clastogenic action. They also find that mei-9 excision repair function is involved in the repair of cis-PDD-induced DNA lesions in a manner that provides additional evidence that partital and ring chromosome losses are not completely homologous.

24 citations


Journal ArticleDOI
TL;DR: A novel chromosome III rearrangement in heterothallic (marl ho) strains is isolated, which is also produced efficiently in marl HO cells, presumably the consequence of a recombination event between HML and HMR.
Abstract: The mating-type switches in the yeast Saccharomyces cerevisiae occur by unidirectional transposition of replicas of unexpressed genetic information, residing at HML or HMR, into the mating-type locus (MAT). The source loci, HML and HMR, remain unchanged. Interestingly, when the HM cassettes are expressed, as in marl strains, the HML and HMR cassettes can also efficiently switch, apparently by obtaining genetic information from either of the other two cassettes (Klar et al., Cell 25:517-524, 1981). We have isolated a novel chromosome III rearrangement in heterothallic (marl ho) strains, which is also produced efficiently in marl HO cells, presumably the consequence of a recombination event between HML and HMR. The fusion results in the loss of sequences which are located distal to HML and to HMR and produces a ring derivative of chromosome III. Cells containing such a ring chromosome are viable as haploids; apparently, no essential loci are located distal to the HM loci. The fusion cassette behaves as a standard HM locus with respect to both regulation by the MAR/SIR control and its role in switching MAT.

24 citations


Journal ArticleDOI
TL;DR: A splenectomized patient with hairy cell leukemia (HCL) who had received chemotherapy with a low-dose alkylating agent for 2 years developed dysmyelopoietic syndrome (DMPS), the first such case to be described.

23 citations


Journal ArticleDOI
TL;DR: The ring chromosome lacked the short arms of the two translocated chromosomes 15 and was duplicated for a portion of the long arms near the centromere, probably cen leads to q13.
Abstract: We describe a boy with a ring chromosome 15, showing the manifestations characteristic of this condition, ie, growth deficiency and unusual facial appearance with minor anomalies. The ring was derived from a t(15q;15q) chromosome of the mother, who had also had four spontaneous abortions. The respective karyotypes were 45,XX, -15,-15,+t(15q;15q) (mother) and 46,XY,-15,+r(15q;15q)mat (15q13 leads to cen leads to 15q26)(son). The ring chromosome lacked the short arms of the two translocated chromosomes 15 and was duplicated for a portion of the long arms near the centromere, probably cen leads to q13. Data from enzyme assays suggest that this duplicated region carries the alpha-mannosidase gene.

23 citations


Journal ArticleDOI
TL;DR: The clinical course of the present case was short, stormy, and had a poor response to therapy, and the correlation between the clinical course and the presence of a ring chromosome in myelo- and lymphoproliferative blood disorders is discussed.

22 citations


Journal ArticleDOI
TL;DR: If a ring 21, originating from breaks close to the telomere of 21q and anywhere in 21p, replaces a normal 21, it may be associated with an apparently normal phenotype, and an apparentlynormal mother and son were ascertained by a prenatal chromosome study.
Abstract: If a ring 21, originating from breaks close to the telomere of 21q and anywhere in 21p, replaces a normal 21, it may be associated with an apparently normal phenotype. An apparently normal mother and son were ascertained by a prenatal chromosome study. A second mother, with a ring 21 but without gross anomalies, is short of stature, has epilepsy and has a low normal intelligence. He daughter is a mosaic: 46,XX/47,XX,+r(21) and has the Down's syndrome. None of these four persons was found to have mitoses with more than one ring 21 or with rings of double size.

Journal ArticleDOI
TL;DR: A fetus was identified by prenatal cytogenetic diagnosis as having a karyotype 46,XY,r(13) (p11q13).
Abstract: A fetus was identified by prenatal cytogenetic diagnosis as having a karyotype 46,XY,r(13) (p11q13). Termination of the pregnancy yielded a severely malformed fetus. Fetal abnormalities included anencephaly, imperforate anus and urethral meatus, severe talipes, syndactyly, cardiac defects and other anomalies. Confirmatory studies on cultured placental villi cells indicated a second cell line, 46,XY, -13,+13qter leads to cen::13q13 leads to qter. This cell line was not detectable in cells derived from the fetus despite extensive studies. It seems likely that the two cell lines arose simultaneously with selection favouring the 46,XY,r(13) line. How the chromosome rearrangements may have arisen is discussed. We are unaware of other cases where a cell line identifiable by a chromosome abnormality appeared to be confined to placental tissue. However, studies on placental tissue may be helpful in understanding the origin of other unbalanced de novo rearrangements.

Journal ArticleDOI
TL;DR: Cytogenetic analysis by Q banding demonstrated minimal chromosome deletion and the karyotype was considered to be 46,XY,r(11) (p15q25) and high resolution G banding showed no visible loss of chromatin.
Abstract: Two cases of ring chromosome 11 are reported. Both had mental retardation, microcephaly, and short stature. High resolution G banding in case 1 showed no visible loss of chromatin, the karyotype being assessed as 46,XX,r(11) (p15 X 4q2 X 5). In case 2, a Wilm's tumour developed at 8 months and the child died at 18 months. Cytogenetic analysis by Q banding demonstrated minimal chromosome deletion and the karyotype was considered to be 46,XY,r(11) (p15q25).

Journal ArticleDOI
TL;DR: A congenital chromosome abnormality was found in two unrelated children with acute lymphoblastic leukemia (ALL) and could be explained by different mechanisms: amplification of oncogenic determinants by gene duplication, and/or alteration of the effects of wildtype alleles through deletion or changes in position.

Journal Article
TL;DR: In this report two non consanguineous children are presented with strikingly similar phenotypes confirming the existence of a characteristic phenotype due to a ring chromosome 14 formation.
Abstract: In this report two non consanguineous children are presented with strikingly similar phenotypes confirming the existence of a characteristic phenotype due to a ring chromosome 14 formation.

Journal ArticleDOI
TL;DR: Chromosome analyses were carried out in lymphocytes of ten children with ALL, prior to and during combined therapy with antineoplastic drugs and cranial irradiation, finding linear dose-effect relationships for dicentric plus ring chromosomes and for excess acentrics could be demonstrated after correction for the relative amount of irradiated volume.
Abstract: Chromosome analyses were carried out in lymphocytes of ten children with ALL, prior to and during combined therapy with antineoplastic drugs and cranial irradiation. Chromosome preparations from group I (four patients) were analysed by conventional staining. For group II (six patients) the FPG technique (fluorescence plus Giemsa) was applied after BrdU treatment of cultures and cells were scored exclusively in first division. A significant clastogenic effect could not be detected in samples collected during or after chemotherapy for either group. After cranial irradiation of those patients in group II, linear dose-effect relationships for dicentric plus ring chromosomes, and for excess acentrics, could be demonstrated after correction for the relative amount of irradiated volume.

Journal ArticleDOI
TL;DR: It is reported that the double minute chromosomes (DMs) are associated with insect tumor cells, similar to the findings in both murine and human tumor cells.

Journal ArticleDOI
TL;DR: A 2-year-old boy with mental and growth retardation is presented; he has a 46,XY,r(10)(p15q26) chromosome complement.
Abstract: A 2-year-old boy with mental and growth retardation is presented; he has a 46,XY,r(10)(p15q26) chromosome complement. Five previously reported cases of ring chromosome 10 were reviewed and compared with the present case in an attempt to delineate a clinical syndrome. Since the first description, identified by Giemsa banding by Lansky et al, four other r(10) patients have been described. Their common features were mental and growth retardation, low birth weight, microcephaly, stubby nose, hypertelorism, strabismus, wide set nipples, single transverse palmar creases, undescended testes, and hypoplastic scrotum. In some of the cases congenital heart disease was present.

Journal ArticleDOI
TL;DR: Taking in conjunction with a higher rate of induced (partial) loss of the rod-Y chromosome of the male with the repair-deficient females suggests the possibility of a greater likelihood that DEB-induced prebreak lesions in ring chromosomes as opposed to rod chromosomes will be eliminated in the presence of the maternal st mus302 genotype.
Abstract: Evidence is presented demonstrating that diepoxybutane (DEB)-induced ring-X loss in sperm/late spermatids of the Drosophila melanogaster male is substantially lower in matings of ring-X males with repair-deficient st mus302 than ordinary females, but the reverse is obtained when rod-X males are so tested. Taken in conjunction with a higher rate of induced (partial) loss of the rod-Y chromosome of the male with the repair-deficient females suggests the possibility of a greater likelihood that DEB-induced prebreak lesions in ring chromosomes as opposed to rod chromosomes will be eliminated (presumably as a dominant lethals) in the presence of the maternal st mus302 genotype.

Journal ArticleDOI
TL;DR: Ring chromosomes were formed in the root tip cells of Allium sativum and A. cepa var.viviparum after treatment with diethyl sulphate and gamma-rays and the behavior of these chromosomes during different stages of somatic cell division is discussed.
Abstract: Ring chromosomes were formed in the root tip cells ofAllium sativum andA. cepa var.viviparum after treatment with diethyl sulphate and gamma-rays. Both centric and acentric types of ring chromosomes were observed. The behavior of these chromosomes during different stages of somatic cell division is discussed.