The ring nature of a tiny supernumerary chromosome fragment

Hoo, Joe J.; Drummond, Margaret; Parslow, M. I.; Chambers, Diana; Kaya, Celia I.

doi:10.1002/ajmg.1320050403

Cited by 9 publications

(4 citation statements)

References 5 publications

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“…A good prognosis in conjunction with a small supernumerary chromosome of 1, 9, or 16 origin was reported in three cases by Callen et al [1990] in which supernumerary ring chromosomes with large amounts of heterochromatin were interpreted as not clinically active. However, the two cases reported by Hoo et al [1974, 1980], which showed heterochromatic regions within the small ring chromosomes, were considered accountable in the presentation of mild mental retardation, although a chance association cannot be excluded.…”

Section: Discussionmentioning

confidence: 99%

Mosaic trisomy of a small r(1) with an abnormal phenotype

et al. 2001

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Cytogenetic studies of a mildly dysmorphic 10-year-old male with mild developmental delay and learning difficulties revealed mosaicism for a supernumerary ring chromosome in approximately half of the cells. The karyotype of this patient was established as 47,XY,+r[15]/46,XY[15].ish r(1)(D1Z7+,wcp1-). Although the presence of euchromatic material was shown by C banding, the lack of hybridization with the whole chromosome paint 1 (wcp1) probe suggests that few unique sequences are contained in the ring and that these sequences likely explain the child's dysmorphic features and developmental delay. A review of the literature, including the present case, suggests that the significance of euchromatin in supernumerary r(1) as determined by both C banding and fluorescence in situ hybridization (FISH) with chromosome 1 painting probes can be used as a prognostic indicator for potential severity of the clinical phenotype.

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Section: Discussionmentioning

confidence: 99%

Mosaic trisomy of a small r(1) with an abnormal phenotype

et al. 2001

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“…Many of these characteristics are present in our patient, whose cytogenetic situation also shows a remarkable stability. Considering her age of nearly 30 years, there seems to have been very little tendency to the euploidization, observed in other cases [Hoo et al, 1980;Benn and Hsu, 19841. The hypothesis of the rings is also supported by the likely exclusion that the supernumerary chromosomes are small bisatellited markers.…”

Section: Djscussjonmentioning

confidence: 99%

“…Occasionally, the accessory chromosomes have been identified as rings [Hoo et al, 1974a[Hoo et al, , 1980Ventruto et al, 1977;Kaffe et al, 1977;Zamboni et al, 1980;Fryns et al, 354 Tozzietal. 198 1, 198% Copeland et al, 19851. As to their clinical significance, the statement can be made that, in general, presence of euchromatin in the mar and de novo appearance in the proband are accompanied by mental retardation, whereas heterochromatic, inherited mar's are in most cases associated with a normal phenotype.…”

Section: Introductionmentioning

confidence: 99%

Multiple “marker” chromosomes: A novel cytogenetic finding in a patient with mental retardation and congenital anomalies

Tozzi¹,

Calvieri²,

Alesi³

et al. 1988

Am. J. Med. Genet.

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A patient with mental retardation and clinical manifestations suggestive of Noonan syndrome was found to have in her peripheral lymphocytes multiple small accessory marker chromosomes, varying in number from one to five per cell and in size from about half the size of the q arm of a G group chromosome to less than a centromere. Occasionally, in the more elongated markers, a G-positive or a C-positive band could be identified, or the marker had the appearance of a ring. The origin and significance of these marker chromosomes are discussed.

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“…Ring chromosomes have long been recognized in classical cytogenetics on the basis of their shape and properties (Hoo et al 1980). A ring chromosome can lead to clinical symptoms due to partial deletion (mohosomy) of that certain chromosome.…”

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confidence: 99%

Supernumerary ring chromosome 20 characterized by fluorescence in situ hybridization

Langen

Otter²,

Aronson³

et al. 1996

Clinical Genetics

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We report on a boy with mild dysmorphic features and developmental delay, in whom karyotyping showed an additional minute ring chromosome in 60% of metaphases. Fluorescence in situ hybridization (FISH) with a centromere specific probe demonstrated that the ring chromosome contained the centromeric region of chromosome 20. The ring was highlighted completely using a chromosome 20 painting probe. A cosmid probe for 20p12‐13 gave a positive signal and hybridization with an all‐telomere probe showed one signal, suggesting a breakpoint in the 20p telomere. The results suggested that only a small part of 20q was involved in this ring. The ring was also detected in 18% of nuclei of a buccal smear. The phenotypic similarities of symptoms in the proband to patients with a (partial) trisomy 20p and the dissimilarities to symptoms in patients with (partial) trisomy 20q were in agreement with the FISH results.

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The ring nature of a tiny supernumerary chromosome fragment

Cited by 9 publications

References 5 publications

Mosaic trisomy of a small r(1) with an abnormal phenotype

Mosaic trisomy of a small r(1) with an abnormal phenotype

Multiple “marker” chromosomes: A novel cytogenetic finding in a patient with mental retardation and congenital anomalies

Supernumerary ring chromosome 20 characterized by fluorescence in situ hybridization

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