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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: It is reported that Bednar tumor and dermatofibrosarcoma protuberans are characterized by the same chromosomal features, and this is the first report that the ring chromosome inBednar tumor is composed of amplified material from chromosomes 17 and 22.
Abstract: Cytogenetic analysis of Bednar tumor (pigmented dermatofibrosarcoma protuberans) has not been reported previously. Here, we report the identification of a supernumerary ring chromosome in a Bednar tumor by chromosome painting with fluorescence in situ hybridization (FISH) and comparative genomic hybridization (CGH). Chromosome painting with FISH demonstrated that the supernumerary ring chromosome was composed of discontinuous, interwoven sequences from chromosomes 17 and 22. Amplification of chromosomes 17 and 22 sequences was confirmed by CGH. These results indicate that Bednar tumor and dermatofibrosarcoma protuberans are characterized by the same chromosomal features. To our knowledge, this is the first report that the ring chromosome in Bednar tumor is composed of amplified material from chromosomes 17 and 22.

40 citations

Journal Article
TL;DR: It is clearly demonstrates that the small ring in this patient originates from three discontinuous regions of chromosome 4: 4p13 or 14, the centromere, and 4q31, and there are at least two mechanisms for the formation of small ring chromosomes.
Abstract: Molecular cloning of a microdissected small accessary ring chromosome 4 from a moderately retarded and dysmorphic patient has been performed to identify the origin of the ring chromosome. FISH was performed with cosmids identified with the cloned, microdissected products and with other markers from chromosome 4. The present study clearly demonstrates that the small ring in this patient originates from three discontinuous regions of chromosome 4: 4p13 or 14, the centromere, and 4q31. It is suggested that the origin of the ring chromosome is a ring involving the entire chromosome 4, which has then been involved in breakage and fusion events, as a consequence of DNA replication generating interlocked rings. A second severely retarded and dysmorphic patient also had a small accessary ring derived from chromosome 4. FISH studies of this ring are consistent with an origin from a contiguous region including the centromere to band 4q12. It is apparent that there are at least two mechanisms for the formation of small ring chromosomes. This adds a further complication in any attempt to ascertain common phenotypes between patients known to have morphologically similar markers derived from the same chromosome.

40 citations

Journal ArticleDOI
TL;DR: The findings in this patient support the hypothesis that lack of X-inactivation of the ring X chromosome in the 46,X,+r(X) cells causes mental retardation, syndactyly, minor facial anomalies, and a congenital heart defect.
Abstract: We present a patient with 45,X/46,X, + r(X) mosaicism and lack of inactivation of either the normal or the ring X in the 46,X, + r(X) cells. The patient has mental retardation, syndactyly, minor facial anomalies, and a congenital heart defect. Although most patients with 45,X/46,X, + r(X) have the Ullrich-Turner syndrome, 2 previously described patients with this karyotype also had a distinct phenotype consisting of severe mental retardation, syndactyly, and abnormal face. The unusually severe phenotype in these patients was thought to be due to lack of X-inactivation of the ring X chromosome. The findings in our patient support this hypothesis.

40 citations

Journal ArticleDOI
TL;DR: A stable ring chromosome 21 was found in an azoospermic man with an otherwise normal phenotype, and eight healthy females with r(21) were fertile, however, they were at risk for Down syndrome and spontaneous abortions.
Abstract: A stable ring chromosome 21 was found in an azoospermic man with an otherwise normal phenotype. Meiotic studies in another known azoospermic male with r(21) had indicated that breakdown of spermatogenesis resulted from pairing failure of chromosome 21, followed by degenerative changes in the chromosomes, before the cells had completed the first meiotic division. While primary sterility was a constant feature in the three adult males, eight healthy females with r(21) were fertile. However, they were at risk for Down syndrome and spontaneous abortions.

40 citations

Journal ArticleDOI
TL;DR: Re reassessment of all 57 reported cases has revealed that the mosaicism ratio is significantly associated with age at seizure onset, intelligence quotient, and malformation, but not with the response of epilepsy to drug treatment.
Abstract: Ring chromosome 20 [r(20)] syndrome is a rare chromosomal disorder characterized by epilepsy, mild to moderate mental impairment, and malformation. Patients generally show mosaicism in 1-100% of lymphocytes with r(20). We report here a patient with r(20) syndrome who exhibited mild phenotype with the small ratio of mosaicism (13%) with r(20). Although previous small-scale studies concluded that the mosaicism ratio was unrelated to clinical phenotype, our reassessment of all 57 reported cases has revealed that the ratio is significantly associated with age at seizure onset, intelligence quotient, and malformation, but not with the response of epilepsy to drug treatment. Our results provide important clinical information and prediction for r(20) syndrome.

40 citations


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