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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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Journal ArticleDOI
TL;DR: Production and repair of chromosome damage were studied in interphase xrs-5 cells by means of premature chromosome condensation (PCC) and the results obtained were compared with those previously reported for CHO cells.
Abstract: SummaryProduction and repair of chromosome damage were studied in interphase xrs-5 cells by means of premature chromosome condensation (PCC). The results obtained were compared with those previously reported for CHO cells. Production of chromosome damage per unit of absorbed radiation dose was in xrs-5 cells larger by a factor of 2·6 than in CHO cells (5·2 breaks per cell per Gy). Changes in chromatin structure, associated with the radiation-sensitive phenotype of xrs-5 cells, that increase the probability of conversion of a DNA double-strand break (dsb) to a chromosome break are invoked to explain this effect. Repair of chromosome breaks as measured in plateau-phase G1 cells was deficient in xrs-5 cells and the number of residual chromosome breaks was practically identical to the number of lethal lesions calculated from survival data. This observation suggests that non-repaired chromosome breaks are likely to be manifestations of lethal events in the cell. The yield of ring chromosomes scored after a few...

61 citations

Journal ArticleDOI
TL;DR: The presence, distribution and copy number level of extra COAS sequences were investigated in 48 bone and soft tissue tumor (BSTT) samples using metaphase FISH analysis, and the role of the frequent coamplification of COAS, or some other yet unknown gene in the 1q21–23 region, and MDM2 remains to be elucidated.
Abstract: Amplifications and gains involving 1q are common abnormalities in solid tumors. Recently, an amplicon originating from 1q21-23, containing the candidate oncogenes COAS1, COAS2 and COAS3 (Chromosome One Amplified Sequence) was identified. The presence, distribution and copy number level of extra COAS sequences were investigated in 48 bone and soft tissue tumor (BSTT) samples using metaphase FISH analysis. Amplification was seen in 27/48 (56%) samples. With few exceptions, all 3 genes were involved, but on average COAS2 exhibited higher copy numbers. The presence of extra COAS signals, irrespective of copy numbers, was found at similar frequencies in different histologic tumor subtypes. However, medium or high level amplification was common in lipomatous tumors but rare in other, nonlipomatous tumors (9/21 vs. 2/27 samples). The most common localization of extra COAS signals in lipomatous tumors was in supernumerary ring and giant marker chromosomes. Among nonlipomatous tumors, the distribution of extra COAS genes was more disperse, being located in various unidentified chromosomal structures, including double minutes, and only rarely in ring chromosomes. Because MDM2 is known to be amplified frequently in BSTTs, and in particular in atypical lipomatous tumors, cases with extra copies of COAS were studied also with an MDM2 probe. Twelve out of 18 lipomatous tumors had extra copies of both COAS and MDM2, and the 2 genes were found to be coamplified and interspersed exclusively in ring and giant marker chromosomes. Also 12 out of 18 nonlipomatous tumors exhibited simultaneous gain of COAS and MDM2, but colocalization in the same chromosome was less frequent. The role of the frequent coamplification of COAS, or some other yet unknown gene in the 1q21-23 region, and MDM2 remains to be elucidated.

61 citations

Journal ArticleDOI
TL;DR: These patients are the first recognized examples of dysgammaglobulinemia associated with a chromosomal deletion of the long arm of the same chromosome.
Abstract: IN CONTRAST to the X chromosome, little is known about the autosomal loci for various genetic traits. Recently Gerald et al1 and Bloom et al 2 have presented suggestive evidence that the controlling formation of locus the α-chain of haptoglobin is situated on one end of a No. 13 chromosome. We have studied two patients with chromosome defects and dysgammaglobulinemia. One had a No. 18 ring chromosome, which is formed by breakage in both arms with reunion of the broken ends and loss of a variable amount of material distal to each break. The other had a partial deletion of the long arm of the same chromosome. In both patients IgA was not detectable, and, in one, the level of IgG was very low. These patients are the first recognized examples of dysgammaglobulinemia associated with a chromosomal deletion. Report of Cases Case 1.—A 3-year-old white boy was first admitted to

61 citations

Journal ArticleDOI
TL;DR: Sequence analysis of breakpoint junctions reveals a normal-copy disomic spacer between inverted and non-inverted copies of the duplication, which supports a mechanism of inverted duplication formation whereby a chromosome with a double-strand break intrastrand pairs with itself to form a “fold-back” intermediate that, after DNA replication, produces a dicentric inverted chromosomes with a disomicSpacer corresponding to the site of the fold-back loop.
Abstract: Inverted duplications are a common type of copy number variation (CNV) in germline and somatic genomes. Large duplications that include many genes can lead to both neurodevelopmental phenotypes in children and gene amplifications in tumors. There are several models for inverted duplication formation, most of which include a dicentric chromosome intermediate followed by breakage-fusion-bridge (BFB) cycles, but the mechanisms that give rise to the inverted dicentric chromosome in most inverted duplications remain unknown. Here we have combined high-resolution array CGH, custom sequence capture, next-generation sequencing, and long-range PCR to analyze the breakpoints of 50 nonrecurrent inverted duplications in patients with intellectual disability, autism, and congenital anomalies. For half of the rearrangements in our study, we sequenced at least one breakpoint junction. Sequence analysis of breakpoint junctions reveals a normal-copy disomic spacer between inverted and non-inverted copies of the duplication. Further, short inverted sequences are present at the boundary of the disomic spacer and the inverted duplication. These data support a mechanism of inverted duplication formation whereby a chromosome with a double-strand break intrastrand pairs with itself to form a “fold-back” intermediate that, after DNA replication, produces a dicentric inverted chromosome with a disomic spacer corresponding to the site of the fold-back loop. This process can lead to inverted duplications adjacent to terminal deletions, inverted duplications juxtaposed to translocations, and inverted duplication ring chromosomes.

61 citations

Journal ArticleDOI
TL;DR: Structural rearrangements of 11q13‐21 were revealed in 9 lipogenic tumors—4 hibernomas, 4 typical lipomas and I mixed myxoid and well‐differentiated liposarcoma, indicating that this segment of chromosome 11 harbors one or more genes of importance in hibernoma development.
Abstract: Cytogenetic analysis revealed structural rearrangements of 11q13-21 in 9 lipogenic tumors--4 hibernomas, 4 typical lipomas and 1 mixed myxoid and well-differentiated liposarcoma. Two hibernomas and all lipomas simultaneously showed aberrations attributable to previously recognized cytogenetic subgroups among benign adipose tissue tumors, i.e., supernumerary ring chromosomes or rearrangements of 6p, 12q13-15, or 13q. The sole anomaly in the liposarcoma was a 4-way translocation t(9;11;22;12)(q21;q13;q11;q13), an aberration that has not previously been detected in either myxoid or well-differentiated liposarcomas. Together with our 4 cases, a total of 7 cytogenetically aberrant hibernomas have been reported. Five tumors have shown rearrangements of 11q13 and 2 of 11q21, indicating that this segment of chromosome 11 harbors one or more genes of importance in hibernoma development. Rearrangements of 11q13-21 also appear to be frequent in typical lipomas; a total of 8 typical lipomas with 11q13-21 changes have been described, including those in our series. In all but 1 however, breakpoints were also found in 6p, 12q13-15, or 13q.

60 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202310
202221
202123
202019
201919
201836