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Showing papers on "Ring chromosome published in 1984"


Journal ArticleDOI
01 Feb 1984-Genetics
TL;DR: It is shown that dicentric ring chromosomes exhibit similar behavior: at least half the time they are not broken during meiosis but are broken and healed during mitosis, and the ring/rod diploid can also be used to determine the frequency of sister chromatid exchange (SCE) along an entire yeast ring chromosome.
Abstract: Meiotic recombination between a circular and a linear chromosome in Saccharomyces cerevisiae has been investigated. The circle was a haploid-viable derivative of chromosome III constructed by joining regions near the two chromosome ends via a recombinant DNA construction: (HMR/MAT-URA3-pBR322-MAT/HML) and was also deleted for MAL2 (which therefore uniquely marks a linear chromosome III). Recombination along chromosome III was measured for eight intervals spanning the entire length of the circular derivative. Only 25% of all tetrads from a ring/rod diploid contained four viable spores. These proved to be cases in which there was either no recombination along chromosome III or in which there were two-strand double crossovers or higher order crossovers that would not produce a dicentric chromosome.--At least half of the tetrads with three viable spores included one Ura+ Mal+ spore that was genetically highly unstable. The Ura+ Mal+ spore colonies gave rise to as many as seven genetically distinct, stable ("healed") derivatives, some of which had lost either URA3 or MAL2. Analysis of markers on chromosome III suggests that dicentric chromosomes frequently do not break during meiosis but are inherited intact into a haploid spore. In mitosis, however, the dicentric chromosome is frequently broken, giving rise to a variety of genetically distinct derivatives. We have also shown that dicentric ring chromosomes exhibit similar behavior: at least half the time they are not broken during meiosis but are broken and healed during mitosis.--The ring/rod diploid can also be used to determine the frequency of sister chromatid exchange (SCE) along an entire yeast ring chromosome. We estimate that an unequal number of SCE events occurs in approximately 15% of all cells undergoing meiosis. In contrast, the mitotic instability (and presumably SCE events) of a ring chromosome is low, occurring at a rate of about 1.2 X 10(-3) per cell division.

123 citations


Journal ArticleDOI
TL;DR: The only chromosome feature common to all nine breast carcinomas was the presence of a marker involving the long arm of chromosome #1, the region shared by all being 1qter----1q21.

120 citations


Journal ArticleDOI
TL;DR: The Miller-Dieker syndrome (MDS) consists of lissencephaly, characteristic facies, pre-and postnatal growth retardation, plus various other birth defects as mentioned in this paper.
Abstract: The Miller-Dieker Syndrome (MDS) consists of lissencephaly, characteristic facies, pre- and postnatal growth retardation, plus various other birth defects. Autosomal recessive inheritance has been presumed based on four reported families with two or more affected siblings. We present substantial evidence that monosomy 17p13.3 causes the MDS phenotype. This includes two patients with ring chromosome 17, one patient with a de novo 17p13 deletion, and one patient with monosomy 17p due to an unbalanced 7p; 17p translocation. We report the first prenatal diagnosis of MDS in a 20-week fetus from this latter family. Additionally, we report a balanced translocation between chromosome 17 and different autosomes (8, 12, and 15) in three of the four familial cases of lissencephaly. The finding of a chromosomal basis for this presumed autosomal recessive disorder significantly alters genetic counseling and makes prenatal diagnosis possible in some families.

102 citations


Journal ArticleDOI
TL;DR: Combined data from this study and the three previously published large series of patients with t-ANLL studied with banding suggest a relationship between karyotype and intensity of prior therapy, with abnormalities of chromosomes #5 and #7 occurring more often in the intensively treated patients.

85 citations


Journal ArticleDOI
TL;DR: The different responses of BS and EM9 cells to growth in BrdU suggest that the molecular defects in the two cell types are different, and the types of aberrations present in CHO cells also were increased greatly in number.
Abstract: Bloom's syndrome (BS) and EM9 cells both display elevated frequencies of sister chromatid exchange (SCE) following growth for two rounds of DNA replication in bromodeoxyuridine (BrdU)-containing medium. To learn whether hyperresponsiveness to BrdU itself might play a role in causing the SCE elevation, the effects of BrdU on two other parameters, cellular proliferation and chromosome disruption, were examined, comparing the responses of BS and normal lymphoblastoid cells and of EM9 and CHO cells. BS and normal cells responded similarly with respect to growth for 4 days in BrdU-containing medium (0, 1, 3, and 5 micrograms/ml). Chromosome aberrations were increased only slightly in the BS and normal cells after 2 days in BrdU. CHO cells responded to growth in BrdU-containing medium like BS and normal cells; however, little growth of EM9 was detected at any of the BrdU concentrations employed. CHO and EM9 cells also exhibited strikingly different amounts of chromosome damage following growth in BrdU. After 2 days in 1, 3, and 5 micrograms/ml BrdU 21%, 46%, and 50%, respectively, of the CHO cells had chromosome aberrations in contrast to 92%, 96%, and 98% of the EM9 cells. Most of the aberrations in the BrdU-treated CHO cells consisted of what appeared to be polycentric and ring chromosomes or chromosomes exhibiting telemere association. Acentric fragments were absent from most cells with polycentric and ring chromosomes, indicating either that the abnormal chromosomes were formed during an earlier cell cycle or that the abnormal chromosomes represent a form of association in which the telomeres are apposed so tightly that the juncture between chromosomes cannot be identified microscopically.(ABSTRACT TRUNCATED AT 250 WORDS)

35 citations


Journal ArticleDOI
TL;DR: In this paper, the authors applied high resolution chromosome analysis and bromodeoxyuridine (BrdUrd) incorporation to study patterns of chromosomal replication (inactivation) in two cases of unbalanced X-autosome translocations, seven cases of X and Y chromosome rings or fragments, and five cases of dicentric isochromosomes (Xq).
Abstract: High resolution chromosome analysis and bromodeoxyuridine (BrdUrd) incorporation have been applied to study patterns of chromosomal replication (inactivation) in two cases of unbalanced X-autosome translocations, seven cases of X and Y chromosome rings or fragments, and five cases of dicentric isochromosomes (Xq). Our results indicate the following: (1) In (X-A) translocations, detailed replicational analysis of the translocated autosomal segment is informative. Absence of "spreading effect" and partial-incomplete spreading effect are the most common observations. (2) Sex chromosome derived fragments and rings can be differentiated based on their replicational features. (3) Dicentric isochromosomes (Xq) can be classified based on intercentromeric distances, replicational asynchrony, and centromere inactivation. (4) A correlation between intercentromeric distance and degree of 45,X mosaicism was observed in dicentric "i(Xq)" chromosomes. Evidence for spreading effect based on our results and on the review of the literature has been critically analyzed and general rules in evaluating spreading effects (SE) proposed. The cytologic detection of active regions on the late replicating X chromosome and the inactivation capacity of the juxtacentromeric region of Xp is evaluated. It is proposed that centromere suppression and underreplication are related phenomena. Finally, the analysis of informative replicational stages is emphasized and the application of their analysis in basic and clinical cytogenetics demonstrated.

33 citations


Journal ArticleDOI
01 Aug 1984-Heredity
TL;DR: There were no correlations between repair ability and rates of genetic damage in isofemale lines of a winery population of Drosophila melanogaster from Australia and possible reasons for the absence of correlation are discussed.
Abstract: To measure the possible correlation between genetic damage and repair ability in natural populations of a eukaryote, we compared the spontaneous frequency of sex-linked recessive lethal mutations and male recombination, which is associated with DNA transposable element induced chromosome breakage, with DNA repair efficiency in isofemale lines of a winery population of Drosophila melanogaster from Australia. Repair efficiency was measured by maternal effects on ring-X chromosome loss. Significant amounts of genetic variability for spontaneous rates of genetic change and for repair ability were observed in the isofemale lines collected during periods of low and high population density. However, there were no correlations between repair ability and rates of genetic damage. Possible reasons for the absence of correlation are discussed, along with the observations that: (a) the frequency of lethal mutations and ring-X chromosome losses were significantly higher in the small, resident population; (b) the rates of ring chromosome losses and especially lethal mutations are uniform over periods of time; (c) and inbreeding of isofemale lines leads to a reduction of the high spontaneous mutation rates.

22 citations


Journal ArticleDOI
01 Dec 1984-Genetics
TL;DR: It is shown that ring X chromosomes are lost meiotically in male Drosophila undergoing ribosomal gene magnification as evidenced by the recovery of a lower number of ring-bearing progeny under magnifying conditions compared with nonmagnifying conditions.
Abstract: Tartof showed that ribosomal gene magnification in Drosophila was inhibited in a ring X chromosome. The present studies extend this observation by showing that ring X chromosomes are lost meiotically in male Drosophila undergoing ribosomal gene magnification as evidenced by the recovery of a lower number of ring-bearing progeny under magnifying conditions compared with nonmagnifying conditions. Associated with ring chromosome loss is a highly significant increase in the number of double-sized dicentric ring chromosomes in meiotic cells from magnifying males. These observations explain the failure of ring X chromosomes to magnify and imply that magnification in rod chromosomes occurs via a mechanism of unequal sister chromatid exchange. Our results support the hypothesis that the primary event of magnification is a sister chromatid exchange in the rDNA, that the frequency of sister strand exchanges is increased in magnifying flies, that a significant number of exchanges in magnifying flies occurs meiotically and that some of the exchanges are nonreciprocal. We have also found that autosomal mutations can affect both the frequency of abnormal ring structures and the ability of ring X chromosomes to magnify.

22 citations


Journal ArticleDOI
TL;DR: Cytogenetic findings of a primary renal-cell carcinoma are reported and the following structural chromosomal abnormalities were identified by the G-banding technique: i(1q), t(3;17), 6q-, 7p+, and a ring chromosome of unknown origin.

21 citations


Journal ArticleDOI
TL;DR: An unstable ring chromosome 21 detected through prenatal studies was associated at birth with an apparently normal male phenotype and the effective trisomy present in many cells studies was insufficient to cause the Down syndrome.
Abstract: An unstable ring chromosome 21 detected through prenatal studies was associated at birth with an apparently normal male phenotype. At 14 months of age, examination indicated only minor developmental delay. The majority of cells examined from amniocyte, fibroblast, and lymphocyte cultures contained an asymmetrical dicentric ring 21 chromosome which was larger than a normal chromosome 21. This ring is presumed to be a duplication for most of chromosome 21 and a deletion of part of the terminal regions. The karyotype is described as mos45, XY,-21/46,XY,r(21)(p13q22.3). The child is monosomic for part of the sub-band 21q22.3 in every cell and trisomic for the remainder of the chromosome in most of his cells. The terminal deletion does not appear to have been severely detrimental to the phenotype and the effective trisomy present in many cells studies was insufficient to cause the Down syndrome.

17 citations


Journal ArticleDOI
TL;DR: An account is given of the cytogenetic investigations of a girl with Down's syndrome found to have a dicentric duplication of chromosome 21, which was interpreted as a recombinant derived from a single meiotic crossover between a maternal ring 21 and its normal homologue.
Abstract: An account is given of the cytogenetic investigations of a girl with Down's syndrome found to have a dicentric duplication of chromosome 21. This tandem type of rearrangement was interpreted as a recombinant derived from a single meiotic crossover between a maternal ring 21 and its normal homologue. A population of cells was also found in which breakage of the dicentric resulted in a chromosome 21 with a small terminal deletion. The mother and the proband's younger brother, who was also a ring 21 heterozygote, were both clinically normal.

Journal Article
TL;DR: A phenotypically normal woman with a ring chromosome 21 in her karyotype, who sought genetic counseling because of her previous reproductive failure and whose third, prenatally diagnosed, pregnancy resulted in the delivery of a healthy and karyotypicallynormal boy.
Abstract: In the present paper we report a phenotypically normal woman with a ring chromosome 21 in her karyotype, who sought genetic counseling because of her previous reproductive failure and whose third, prenatally diagnosed, pregnancy resulted in the delivery of a healthy and karyotypically normal boy.

Journal Article
TL;DR: The case of a male child with three cell lines is described: one cell line with ring chromosome 14, another trisomic for 14q, due to a derived metacentric 14q;14q, and a third one with a normal male karyotype, compatible with those of the r(14) syndrome.
Abstract: The case of a male child with three cell lines is described: one cell line with ring chromosome 14, another trisomic for 14q, due to a derived metacentric 14q;14q, and a third one with a normal male karyotype The clinical findings are compatible with those of the r(14) syndrome

Journal ArticleDOI
TL;DR: Synthesis of clinical, enzymatic and cytogenetic findings confirms that the superoxide dismutase A (SOD-A) locus is in sub-band 21q22-1, however, it is not possible to localize precisely the segments responsible for the different clinical features of 21q — syndrome.
Abstract: Three patients with partial monosomy of the long arm of chromosome 21 are reported. Each one presents several features of a 21q—syndrome but in cases 2 and 3, other chromosomes are involved, contributing to the variability of the clinical picture. Synthesis of clinical, enzymatic and cytogenetic findings confirms that the superoxide dismutase A (SOD-A) locus is in sub-band 21q22-1. However, it is not possible to localize precisely the segments responsible for the different clinical features of 21q — syndrome.

Journal ArticleDOI
J. Otto, E. Back1, H. O. Fürste, M. Abel, N. Böhm, W. Pringsheim 
TL;DR: A 20-day-old female neonate was admitted with symptoms caused by a large ventricular septal defect which was subsequently confirmed angiographically and Cytogenetic analysis revealed a ring chromosome 15.
Abstract: A 20-day-old female neonate was admitted with symptoms caused by a large ventricular septal defect which was subsequently confirmed angiographically. Other clinical findings were pre-and postnatal growth retardation, microcephaly, dysmorphism of ears, fingers and feet. Cytogenetic analysis revealed a ring chromosome 15. Despite a palliative banding operation of the pulmonary artery, the infant succumbed to complications of her congenital heart disease in the 4th month of life.


Journal ArticleDOI
TL;DR: The normal serum Ig levels found in the proposita are compatible with the suggestion that the Ig loci are not located on the terminal portion of 14q but more proximally in band 14q32, however, because Gm and Am allotyping was not available mapping was not conclusive.
Abstract: A 2.5-yr-old girl was evaluated for seizurelike episodes and psychomotor and growth retardation. Cytogenetic study showed a ring 14 chromosome in most cells, with some cells having monosomy 14. Rarely, a cell showed a double ring chromosome 14. Both parents had normal chromosomes. Because serum immunoglobulins have been mapped to the distal portion of 14q, we attempted to correlate Ig levels with the deletion involved in the formation of this ring. No decrease in IgG, IgM, IgA, IgE, and IgD serum levels was observed. The normal serum Ig levels found in the proposita are compatible with the suggestion that the Ig loci are not located on the terminal portion of 14q but more proximally in band 14q32. However, because Gm and Am allotyping was not available mapping was not conclusive.

Journal Article
TL;DR: A ring chromosome derived from a no. 14 was observed, without mosaicism, in a 2-month-old male with craniofacial dysmorphism, retarded psychomotor development, seizures and retinal anomalies.
Abstract: A ring chromosome derived from a no. 14 was observed, without mosaicism, in a 2-month-old male with craniofacial dysmorphism, retarded psychomotor development, seizures and retinal anomalies. Serum immunoglobulins concentrations were normal.

Journal ArticleDOI
TL;DR: A girl with the karyotype 46,XX,3,+r(3) (p26q29) had growth and borderline mental retardation, craniofacial anomalies and microcephalus.
Abstract: We will discuss a girl with the karyotype 46,XX,-3,+r(3) (p26q29). She had growth and borderline mental retardation, craniofacial anomalies and microcephalus.

Journal ArticleDOI
TL;DR: The diagnostic x-ray combined with the presence of each contrast medium demonstrated a slight increase in SCE frequency compared to that of the controls, however, it could not identify any specific medium among these contrast media that was conspicuously toxic or clastogenic to chromosomes.
Abstract: On the present in vitro study with or without x-ray exposure, employing the sister chromatid exchange (SCE) analysis as well as the conventional chromosome investigation, we studied the effects of six contrast media, normally used in daily radiodiagnostic procedures, on the peripheral lymphocyte chromosomes. The conventional chromosome analysis demonstrated that the frequency of chromosome-type aberrations such as dicentric and ring chromosomes was not elevated solely by the addition of contrast media at cultivation. The diagnostic x-ray combined with the presence of each contrast medium demonstrated a slight increase in SCE frequency compared to that of the controls. However, we could not identify any specific medium among these contrast media that was conspicuously toxic or clastogenic to chromosomes.

Journal ArticleDOI
TL;DR: The patient was born at 38 weeks' gestation and was very small, with an abnormal face with a sloping forehead, prominent nose, thin lips, and micrognathia and the hands were radially deviated, with absent first metacarpals, and hypoplastic thumbs.
Abstract: The patient was born at 38 weeks' gestation and was very small, weight 1.48 kg (approximately 1 kg below the 3rd centile), length 42 cm (5 cm below the 3rd centile), and head circumference 28 cm (4 cm below the 3rd centile). She had an abnormal face with a sloping forehead, prominent nose, thin lips, and micrognathia. The hands were radially deviated, with absent first metacarpals, and hypoplastic thumbs (fig 1). The right thumb was attached by only a narrow pedicle and the left had no tendinous attachment. Both were biphalangeal. Her subsequent development has been retarded and at a recent assessment at 2 years 3 months she was functioning at a 9 month level. She remained very small, with a weight of 6 kg, length 68 cm, and head circumference 38-5 cm, being respectively 4 kg, 12 cm, and 7 cm below the 3rd centile. G and C banding was done on 72 hour cultured lymphocytes. Most cells had a ring chromosome 1, in which no loss or gain of chromosomal material could be detected (fig 2). In a few cells, variant rings were seen. Some showed a duplication of bands Iq24-44, some had a very long dicentric chromosome, which appeared to be a duplicated and broken ring, and in some cells

Book ChapterDOI
01 Jan 1984
TL;DR: The results show that in this species a wide range of variation can be induced by a dicentric chromosome.
Abstract: M2 M3 and M4 plants of Vicia faba derived from an M1 variegated plant characterized by a dicentric chromosome were analysed by cytologic and phenotypic methods. Genomic structures with dicentric, telocentric, ring and metacentric chromosomes, and triploid plants were found. Mutants for sterility, earliness, plant height and leaf shape were also identified. The results show that in this species a wide range of variation can be induced by a dicentric chromosome.

Journal ArticleDOI
TL;DR: Their features support the idea that ring chromosome X should be considered as a deletion in the genetic sense, affecting both the gonadal and statural determinants, and endocrine data and histologic examination of the gonads are indistinguishable from those of individuals with 45,X or 46XX gonadal dysgenesis.

Journal Article
TL;DR: A case of a female infant with karyotype 46,XX,r(21)/45,XX,-21 is reported and the large variability of the 21q- syndrome is evident.
Abstract: A case of a female infant with karyotype 46,XX,r(21)/45,XX,-21 is reported. From comparison of the phenotypic anomalies with the other similar cases the large variability of the 21q- syndrome is evident.

01 Jan 1984
TL;DR: A mathematical model has been suggested to describe the processes of formation, multiplication and death of the cells with dicentrics and it has been shown that approximately 1/4 of survived acentric structures can diverge to both daughter cells.
Abstract: The regularities of elimination of gamma-ray induced chromosome aberrations in human nonstimulated lymphocytes and the fate of aberrant cells have been studied. The cells at the first, second and third post-irradiation divisions were identified by the technique of differential staining of sister chromatids. A mathematical model has been suggested to describe the processes of formation, multiplication and death of the cells with dicentrics. This model has been shown to be in a good agreement with the experimental data. According to the model, the distribution of dicentrics among cells at the first and second mitoses follows the Poisson distribution. The analysis of the model has shown that the probability of divergence of two chromatids from one dicentric chromosome is equal 1/2, and that the acentric and monocentric types of chromosome aberrations have no influence upon cell survival in vitro. A method for empirical estimation of survival of other types of aberrations has been suggested. According to these estimates, the probabilities of transmission to the next mitosis are equal 2/3, 1 and 1/3 for paired fragments, ring chromosomes and interstitial deletions, respectively. It has been shown that approximately 1/4 of survived acentric structures can diverge to both daughter cells.

Journal Article
TL;DR: The silver staining techniques was used to study two cases of ring chromosomes (ring chromosome 15 and ring chromosome 22) and three cases of small extra chromosomes and provides some information about the origin of smallextra chromosomes.
Abstract: The silver staining techniques was used to study two cases of ring chromosomes (ring chromosome 15 and ring chromosome 22) and two cases of small extra chromosomes. This technique allows identification of the breakpoints and provides some information about the origin of small extra chromosomes.

Journal ArticleDOI
01 Jan 1984
TL;DR: A case of ring chromosome no. 18 (46, XX, r(18) (p11q23)) is presented, and the patient is a 15 year-old-girl, and showed flat nasal base, simianline and mental retardation.
Abstract: A case of ring chromosome no. 18 (46, XX, r(18) (p11q23)) is presented. The patient is a 15 year-old-girl, and showed flat nasal base, simianline and mental retardation.