Topic
Ring chromosome
About: Ring chromosome is a research topic. Over the lifetime, 1546 publications have been published within this topic receiving 31061 citations. The topic is also known as: supernumerary circular chromosome.
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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
35 citations
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
TL;DR: Cytogenetic analysis of short-term cultures from ten giant cell tumors of bone revealed clonal and nonclonal chromosome abnormalities in three tumors and nonClonal changes only in seven and telomeric associations were found in five tumors.
34 citations
Journal Article•
TL;DR: The cytogenetic findings in 478 patients with Turner syndrome diagnosed in Leuven in the period 1965-1989 are presented and compared with previous reported surveys on subject.
Abstract: In this report, we present the cytogenetic findings in 478 patients with Turner syndrome diagnosed in Leuven in the period 1965-1989. The karyotypic anomalies are classified into seven groups: 1) classic, 45,X karyotype (52.1%); 2) mosaic 45,X/46,XX (10.9%); 3) mosaic 45,X/47,XXX and other "super-female" cell lines (4.6%); 4) isochromosomes i(Xq) and i(Xp) (16.1%); 5) ring chromosomes r(X) (4.4%); 6) other structural aberrations of the X chromosome (7.7%); and finally 7) mosaic 45,X/46,XY patients (4%). The most pertinent chromosomal findings are briefly discussed and compared with previous reported surveys on subject.
34 citations