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.

Frequencies of X-ray induced pericentric inversions and centric rings in human blood lymphocytes detected by FISH using chromosome arm specific DNA libraries.

Abstract: Frequencies of intra-chromosomal exchanges (pericentric inversions and centric rings) and inter-chromosomal exchanges (dicentrics and translocations) in X-irradiated (2.5 Gy) human lymphocytes have been estimated. To detect these events we employed FISH (fluorescence in situ hybridization) technique and arm specific painting probes for chromosomes #1 and #3. The ratio between centric rings and pericentric inversions was found to be about 1. For intra-changes to inter-changes, the ratio (F) was between 6 and 9. Based on the total number of colour junctions involving chromosomes #1 and #3 it was found that exchanges between the arms of the same chromosome occur about 8.7 times more than inter-chromosomal exchanges calculated on the basis of the DNA content of the chromosomes and random induction of aberrations in the total genome. Chromosomal organization in interphase nucleus appears to promote the formation of more intra-changes than inter-changes following X-irradiation, most probably due to close proximity of the two arms of a chromosome.

Social, communicational, and behavioral deficits associated with ring X turner syndrome.

Abstract: We describe the cognitive and behavioral characteristics of five individuals with a ring X chromosome. All subjects had a small active (early replicating) ring X chromosome. The X inactive specific transcript (XIST) locus was confirmed by fluorescent in situ hybridisation (FISH) to be present in all ring X chromosomes. Mental retardation was present in four individuals. All patients with or without mental retardation had a characteristic profile of aggression toward self and others, episodes of screaming, attentional problems, and impulsiveness. Autistic-like features were also present in all individuals and included limited communication, obsessive compulsive behavior, and social difficulties. In some cases the obsessive behavior was extreme and incapacitating. This characteristic behavioral profile may aid the diagnosis and future understanding of ring X.

A mosaic 45,X/46,X,r(?) karyotype investigated with X and Y centromere-specific probes using a non-autoradiographic in situ hybridization technique.

Abstract: The sex-chromosomal origin of the ring chromosome in a pre-pubertal non-virilized female patient presenting with a 45,X/46,X,r(?) karyotype could not be resolved by conventional cytogenetic (including G11) methods. Non-autoradiographic in situ hybridization of biotinylated X and Y centromere-specific alphoid repetitive sequence probes unequivocally and rapidly identified the ring to be of X origin.

Duplication of chromosome segment 12q15‐24 is associated with atypical lipomatous tumors. A report of the CHAMP collaborative study group

Abstract: Ordinary lipomas are cytogenetically characterized by a variety of balanced rearrangements involving chromosome segment 12ql3-15, and atypical lipomatous tumors (ALT) by supernumerary ring chromosomes or giant markers known to contain amplified 12q sequences. In a series of 228 cytogenetically analyzed and histopathologically reexamined ordinary lipomas and ALT, 10 tumors showed unbalanced chromosome-12 aberrations. All 4 tumors with loss of segments from 12q were classified as ordinary lipomas, whereas 5 of the 6 tumors showing gain of 12q material were diagnosed as ALT. One or three extra copies of 12q15-q24 were present in all 5 ALT. We conclude that duplication of 12q sequences may be a sufficient level of amplification for development of the microscopic appearance that characterizes ALT.