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Showing papers on "Ring chromosome published in 1982"


Journal ArticleDOI
TL;DR: Somatic chromosomes derived from lymphocytes of 23 Hiroshima A-bomb survivors were analyzed to determine the type and frequency of radiation-induced chromosome aberrations, using both the ordinary staining method (0-method) and the trypsin G-banding method (G-method).
Abstract: Somatic chromosomes derived from lymphocytes of 23 Hiroshima A-bomb survivors were analyzed to determine the type and frequency of radiation-induced chromosome aberrations, using both the ordinary staining method (0-method) and the trypsin G-banding method (G-method). Of 896 cells examined, 342 had aberrations, including 31 unidentifiable cells even by the G-method. The number of aberrations detected was 376 in 311 cells. The majority of them were intra or inter-chromosomal symmetric exchanges, while only 24 were found to be asymmetric exchanges (dicentrics, rings and interstitial deletions). Further, 28 aberrations included acentric fragments and terminal deletions, and the remaining 36 were complex intraand inter-chromosomal exchanges showing insertions and double translocations. An analysis of the same metaphases examined by sequential 0 and G-methods was carried out independently on 361 aberrations. It was found that 78 were detectable only by the Gmethod; among these were 14 paracentric inversions, 48 reciprocal interchanges of chromosome segments with either equal or unequal length, 14 minor deletions and 2 complex rearrangements, all of which were judged as the normal variation by the O-method. In contrast, 25 aberrations detected by the 0-method were found to show normal banding patterns by the G-method.

30 citations


Journal ArticleDOI
TL;DR: The most characteristic findings in subjects with a ring chromosome 6 are mental retardation and eye and ear abnormalities, none of which were present in the authors' patient.
Abstract: A ring chromosome 6 was identified in an apparently healthy girl with short stature and microcephaly. Of 100 peripheral lymphocyte metaphases analyzed, chromosome 6 was replaced in 73% by a monocentric ring chromosome, in 10% by a dicentric, in 1% by a tricentric, and 3% by two rings. Thirteen other cells were 45,XX, −6, which may represent 46,XX,r(6)/45,XX, −6 mosaicism. The breakpoints were located on bands p24 or p25 and q26 or q27. Eight other patients with a ring chromosome 6 have been reported. The most characteristic findings in subjects with a ring chromosome 6 are mental retardation and eye and ear abonormalities, none of which were present in our patient.

29 citations


Journal ArticleDOI
TL;DR: Analysis of three new unrelated cases of the ring chromosome 13 syndrome indicates that the syndrome forms a continuous spectrum, and no further taxonomic subdivision is possible at this stage of knowledge.
Abstract: A study of the ring chromosome 13 syndrome is presented with detailed clinical and cytogenetic features of three new unrelated cases. The clinical limits of this syndrome can now be defined. An analysis of these cases together with those in the literature indicates that the syndrome forms a continuous spectrum, and no further taxonomic subdivision is possible at this stage of knowledge. The chromosome breakpoints in the first two cases are 13p11 and 13q32 and in the third case 13p11 and 13q33 or 13q34. All described cases of the ring 13 syndrome have breakpoints within the region bounded by bands 13q21 to 13q34. All rings are negative for silver banding. Peripheral blood cultures showed an average of 88% of metaphases to be 46.XX,r(13), with the remaining 12% manifesting either random loss or ring duplication. The rings vary in size and show a variable number of centromeres. An estimate of the birth incidence of this condition in the Anglo-Saxon population is 1 in 58,000. Parents of affected children are clincally and cytogenetically normal, the rings in affected offspring being meiotic in origin.

28 citations


Journal ArticleDOI
TL;DR: A new case of ring chromosome 2 is described and compared with the five cases hitherto reported, with a severe pre- and postnatal growth failure, microcephaly, psychomotor retardation, and some minor dysmorphic features.
Abstract: A new case of ring chromosome 2 is described and compared with the five cases hitherto reported. The clinical picture includes a severe pre- and postnatal growth failure, microcephaly, psychomotor retardation, and some minor dysmorphic features. Cytogenetic studies revealed a ring 2 structure and aneuploidy. Banding analysis failed to demonstrate a substantial loss of chromosomal material. Enzymologic studies revealed a decrease of red cell acid phosphatase activity suggesting the localization of its gene in the 2p25→2pter region.

18 citations


Journal ArticleDOI
TL;DR: A young, mentally retarded man with seizures was discovered to have a ring chromosome 17 and the patient's deletion and genotype allowed us to reduce further the chromosome location of the acid alpha-glucosidase gene.
Abstract: A young, mentally retarded man with seizures was discovered to have a ring chromosome 17. He had no major anomalies. The phenotype associated with r(17) probably is variable. The patient's deletion and genotype allowed us to reduce further the chromosome location of the acid alpha-glucosidase gene.

17 citations


Journal ArticleDOI
TL;DR: A male child with mental retardation and poor growth was found to have a 46,XY,r3 (p26 leads to q29) karyotype in 92% of his peripheral lymphocytes and 90%" of his cultured fibroblasts.
Abstract: A male child with mental retardation and poor growth was found to have a 46,XY,r3 (p26 leads to q29) karyotype in 92% of his peripheral lymphocytes and 90% of his cultured fibroblasts. Comparison of this patient's dysmorphic features with previously reported cases of ring 3 or deletion 3p suggests a clinical syndrome derived mainly from deletion of 3p26 leads to pter. The syndrome consists of mental retardation, pre- and postnatal growth retardation, microcephaly, hypertonia, digital anomalies, and a characteristic facies with ptosis, epicanthal folds, broad nasal root, down-turned corners of the mouth, and dysplastic ears.

14 citations


Journal Article
TL;DR: A ring chromosome 14 with breakpoints at 14p11 and 14q31 and positive C- and Ag NOR-banding is reported in a 12.5 years old deeply mentally retarded female with minor dysmorphic syndrome.
Abstract: A ring chromosome 14 with breakpoints at 14p11 and 14q31 and positive C- and Ag NOR-banding is reported in a 12.5 years old deeply mentally retarded female with minor dysmorphic syndrome.

11 citations


Journal Article
TL;DR: Two cases of t(21q21q)/r[t(21Q21q)] mosaic in unrelated infants, 17 and 14 months old respectively are reported and the origin of this unusual mosaicism as well as the significance of the difference in the proportions of the ring chromosome in the two have been discussed.
Abstract: Two cases of t(21q21q)/r[t(21q21q)] mosaic in unrelated infants, 17 and 14 months old respectively are reported. The proportion of cells with the ring chromosome was 45% in the former, 80% in the latter. Both cases had mild manifestations of the Down's syndrome. The origin of this unusual mosaicism as well as the significance of the difference in the proportions of the ring chromosome in the two have been discussed.

9 citations


Journal ArticleDOI
01 Oct 1982-Genetics
TL;DR: Experiments described here have unveiled a diverse class of genes that exert a maternal effect on the behavior during cleavage of these "filicidal" ring chromosomes.
Abstract: Ring-Y chromosomes are recovered infrequently from crosses of ring-Y-bearing males to females of certain strains (Oster 1964). Experiments described here have unveiled a diverse class of genes that exert a maternal effect on the behavior during cleavage of these "filicidal" ring chromosomes. Cytological observations of inviable embryos have revealed that the ring-Y chromosome causes gross disorganization of the cleavage nuclei. This inviability may be equivalent to the "dominant lethality" attributed to unstable ring-X chromosomes (Hinton 1955; Pasztor 1971). Mapping studies indicate that no single region of the normal Y is solely responsible for the unusual behavior of ring-Y chromosomes.

6 citations


Journal Article
TL;DR: A teenage girl with growth and mental retardation, urinary tract and eye abnormalities was found to have an r(10)(p15q26) in blood cells and quantitative evaluation of seven red cell enzymes gave normal values.
Abstract: A teenage girl with growth and mental retardation, urinary tract and eye abnormalities was found to have an r(10)(p15q26) in blood cells. Quantitative evaluation of seven red cell enzymes including three (HK1, TGOS, PGAMA) known to be on chromosome 10, gave normal values.

5 citations


Journal ArticleDOI
TL;DR: Daily feeding of the common food color Orange II to mice in doses of up to 3.0 g/kg b.wt for 180 days had deleterious effects on somatic and spermatogonial chromosomes.
Abstract: Daily feeding of the common food color Orange II to mice in doses of up to 3.0 g/kg b.wt for 180 days had deleterious effects on somatic and spermatogonial chromosomes. The chromosomal abnormalities induced were breaks, gaps, constrictions, centric fusion, fragments of unknown origin, translocation, deletion, stickiness, ring chromosomes, pyknosis and other bizarre configurations.




Journal ArticleDOI
TL;DR: In this paper, a child with malformation syndrome of microcephaly, asymmetrical radius aplasia, and cleft of lip and palate, who was mosaic for a chromosome marker and/or ring of unknown origin was reported.
Abstract: We report a child with malformation syndrome of microcephaly, asymmetrical radius aplasia, and cleft of lip and palate, who was mosaic for a chromosome marker and/or ring of unknown origin. In view of the reported cases of limb deficiency with chromosome abnormalities and the unlikelihood that the patient has a recognized genetic syndrome, the cause of the patient's syndrome may well be the extra chromosomal material.

01 Dec 1982
TL;DR: A child with malformation syndrome of microcephaly, asymmetrical radius aplasia, and cleft of lip and palate, who was mosaic for a chromosome marker and/or ring of unknown origin is reported.