Showing papers on "Ring chromosome published in 1976"

Chromosomal breakage in systemic sclerosis and related disorders.

Abstract: Chromosome aberrations such as gaps and breaks of one or both chromatids, acentric fragments, dicentrics, ring chromosomes and other abnormal chromosomes are observed in lymphocyte and fibroblast cultures as well as in direct bone marrow preparations from patients with systemic sclerosis. A serum factor producing chromosome breaks in mitoses from healthy donors was observed in 37 of 42 scleroderma patients. The biochemical nature of this breakage factor is still undefined. Increased breakage is also noted in a high percentage of healthy family members of scleroderma patients. It is also a common feature of related disorders such as lupus erythematosus, dermatomyositis, periarteritis nodosa and rheumatoid arthritis. An increase in chromosome breaks and rearrangements is also present in NZB mice developing spontaneously an autoimmune disorder that has been extensively studied by workers interested in lupus erythematosus. The similarity of the cytogenetic findings provides the opportunity to use these mice as an experimental model to investigate relationships between immunological perturbations and chromosomal aberrations.

Mental Retardation and Congenital Malformations Associated with a Ring Chromosome 9

Abstract: A 46,XY,r(9)(p24q34) complement was observed in a 35-month-old boy with multiple congenital anomalies. The main clinical features included intrauterine growth retardation, dwarfism, microcephaly, peculiar face, undescended testes, seizures and severe psychomotor retadation.

Ring chromosome 15 in child with a minor dysmorphism of phenotype.

Abstract: The analysis of a karyotype of a girl with slight mental retardation, without significant dysmorphism, showed the presence of a ring chromosome in group 13–15. By the application of G technique it was discovered that in this case it was an aberrant chromosome 15.

Fifty-three month persistence of ring chromosome in noninvasive bladder carcinoma.

Abstract: In a recurrent noninvasive papillary carcinoma of the bladder cytogenetic analysis by the direct technique was carried out on cystoscopic biopsies obtained at 53 month intervals. Persistent similar karyotypic abnormalities including aneuploidy, and ring and other marker chromosomes, the hallmarks of invasive cancer, were present in both specimens. In the 1973 specimen, DNA banding was identified in 35 per cent of the metaphases and in 56 per cent of the karyotypes. The continuing abnormal chromosomal silhouette of this tumor supports the stemline cell concept for malignancies, even when applied to such relatively benign neoplasms as this noninvasive carcinoma of the bladder.

21 ring chromosome in a girl with stigmata of Down's and G deletion I syndromes.

Abstract: An 11-year-old girl with severe psychomotor retardation and other congenital anomalies characteristic of Down's and G deletion I syndromes, was confirmed to be a chromosome 21 ring carrier by R- and G-banding techniques. The dynamics of the ring evolution resulting in a population of complex unstable rings, as in our index case, and the effects of the consequent ring mosaicism are briefly discussed.

Parental origin of a ring 13 chromosome in a female with multiple anomalies.

Abstract: A ring chromosome No 13 was found in a 21-year-old female with multiple anomalies suggestive of 13q-syndrome Chromosomes of the girl and her parents, studied by quinacrine staining, revealed the ring to be of paternal origin Detailed study of the quinacrine banding pattern of the ring indicated loss of the most distal band of the long arm (13q34) and possible partial loss of the next adjacent long arm band (13q33) The short arm (13q11) was present but the stalk (13p12) and satellite (13p13) regions appeared to be missing

A case of ring chromosome.

Abstract: A girl with a G22 ring chromosome is described. There are few physical abnormalities, performance quotient is in the low normal range but verbal skills are much retarded.

D13 ring chromosome syndrome.

Abstract: A case of ring D13 chromosome, confirmed by trypsin banding, is described. Reviewing 21 cases from published reports, the most common features of this syndrome are microcephaly and associated mental retardation, poor uterine growth, deformed auricles, hypertelorism, epicanthus, broad nasal bridge, and genital defects in males.

On the continuity of chromosomal subunits: an analysis of induced ring chromosomes in Vicia faba

Abstract: The proposition that subunits of a chromatid are continuous in a directional sense has been tested by observing the behaviour of induced ring chromosomes in Vicia faba. On the simplest hypothesis, that the subunits are the uninterrupted complementary strands of the DNA molecule, the polarity of rejoining should result in free separation of rings following replication in successive cell cycles. Centric and acentric ring chromosomes were separately assessed in both diploid and colchicine-accumulated tetraploid metaphase cells of primary root tips. Contrary to expectation large numbers of single and interlocked rings were observed in both cell cycles. Spontaneous sister chromatid exchanges and other breakage-reunion events can produce the configurations seen; with the postulated level of sister chromatid exchange equating that determined autoradiographically in rod chromosomes of V. faba. Unless the replication of ring chromosomes produces conditions unusual in rod chromosome replication, spontaneous breakage is probably common in replicating or post replication Vicia chromosomes. — A fundamental difference exists between the behaviour of centric and acentric ring chromosomes. Acentric ring chromosomes behave as if the chromatid arm were one DNA molecule, or a number of DNA molecules with identical directional sense. However, centric ring chromosomes behave as if there were a difference at the centromere in at least one (probably the metacentric) chromosome of the Vicia complement. That is, the two “duplication-segregation” subunits which extend the length of the chromosome, may contain a change in polarity at the centromere.