Topic
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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TL;DR: Cytogenetic analysis of cultured umbilical cord tissue after termination confirmed the finding of ring chromosome 18/monosomy 18 mosaicism and the karyotype was 46,XY,r(18), while short‐term and long‐term cultured chorionic villi showed a normal male karyotypes of 46, XY.
Abstract: A case of complete karyotype discrepancy between cultured chorionic villi and amniotic in addition to fetal cells is reported. Ring chromosome 18 and monosomy 18 mosaicism was detected after amniocentesis. The pregnancy was terminated in the 23rd gestational week. Cytogenetic analysis of cultured umbilical cord tissue after termination confirmed the finding of ring chromosome 18/monosomy 18 mosaicism. In cultured umbilical blood lymphocytes monosomic cells 45,-18 were not detected and the karyotype was 46,XY,r(18). In contrast, short-term and long-term cultured chorionic villi showed a normal male karyotype of 46,XY. Ultrasonographic examination revealed amniotic band syndrome and scoliosis in the caudal region of the spine.
12 citations
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TL;DR: An unstable Ring-X chromosome, DDC+ -Ring-X carrying a cloned Dopa decarboxylase (Ddc) encoding segment was constructed andalyses of Ddc mosaics revealed that while there was no absolute requirement for the Ddc+ expression in either the epidermis or the nervous system, very large mutant clones did affect the viability of the mosaic.
Abstract: An unstable Ring-X chromosome, Ddc+ -Ring-X carrying a cloned Dopa decarboxylase (Ddc) encoding segment was constructed. The construction involved a double recombination event between the unstable Ring-X, R(1)wvC and a Rod-X chromosome which contained a P-element mediated Ddc+ insert. The resulting Ddc+ -Ring-X chromosome behaves similarly to the parent chromosome with respect to somatic instability. The Ddc+ -Ring-X chromosome was used to generate Ddc mosaics. Analyses of Ddc mosaics revealed that while there was no absolute requirement for the Ddc+ expression in either the epidermis or the nervous system, very large mutant clones did affect the viability of the mosaic.
12 citations
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TL;DR: This is the first report of a partial tetrasomy to hexasomy due to a ring chromosome 7, and the ring evolution could be reconstructed according to the FISH‐results.
Abstract: We report on a girl with mosaicism (65%) of a de novo supernumerary ring chromosome 7. The main clinical features were delayed psychomotor development, congenital heart defect, facial dysmorphisms, and long hands, fingers, feet and toes. Molecular cytogenetic analysis revealed that the ring chromosome was duplicated in 20% of the analyzed metaphases with marker chromosome and quadruplicated in 5% thereof. Uniparental disomy (UPD) of the two normal sister chromosomes 7 was excluded. This is, to our knowledge, the first report of a partial tetrasomy to hexasomy due to a ring chromosome 7. Additionally, the ring evolution could be reconstructed according to the FISH-results.
12 citations
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TL;DR: Since the child lacks the classical phenotype of Down syndrome, further studies of the DNA distal to the breakpoint on the long arm of chromosome 21 may help to elucidate "genes" important to the phenotype of down syndrome.
Abstract: We have presented studies of an unusual child with an r21 chromosome who lacks the phenotype of Down syndrome. We have sequenced the region of the breakpoint in the normal DNA fragment and have isolated the abnormal breakpoint fragment as a 7.5-kb EcoRI fragment. We have preliminary evidence localizing the breakpoint to a few hundred base pairs of 21q DNA. Since the child lacks the classical phenotype of Down syndrome, further studies of the DNA distal to the breakpoint on the long arm of chromosome 21 may help us to elucidate "genes" important to the phenotype of Down syndrome.
12 citations
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TL;DR: A 4-year-old child with a ring 20 chromosome mosaicism, low grade developmental delay, and seizures is described.
Abstract: A 4-year-old child with a ring 20 chromosome mosaicism, low grade developmental delay, and seizures is described.
12 citations