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.

Ring 17 chromosome detected by amniocentesis.

Abstract: A fetus with a 46,XX,r(17) karyotype identified initially by amniocentesis and confirmed by banding studies is described. No significant phenotypic abnormalities were identified despite isolation of the ring chromosome from multiple fetal tissues. This paucity of abnormal features of gross development is consistent with findings in 3 previously reported patients with ring 17 chromosomes.

Ring chromosome 21 in a boy and a derivative chromosome 21 in the mother: implication for ring chromosome formation.

Abstract: We report on r(21) chromosome in a boy and a der(21) chromosome in his mother. Cytogenetic studies revealed a mosaic 45,XY[4]/46,XY,r(21)[96] karyotype in the boy and a 46,XX,der(21)[100] karyotype in the mother. Fluorescence in situ hybridization analysis for D21Z1 at the centromere, AML1 at 21q22.1, LSI21 at 21q22.2, and 21qtel at the telomere region showed that the r(21) chromosome retained single copies of D21Z1, AML1, and LSI21 and lacked the 21qtel, whereas the der(21) chromosome had two copies of the 21qtel on both of its ends and single copies of D21Z1, AML1, and LSI21, with a paracentric inversion of AML1 and LSI21 (21qtel–D21Z1–LSI21–AML1–21qtel). Microsatellite analysis for nine loci on 21q22.3 indicated that the r(21) chromosome was missing a distal 21q22.3 region involving D21S1890, D21S1411, and D21S1903 with no maternally derived alleles, and that the der(21) chromosome was associated with duplication of a distal 21q22.3 region encompassing D21S1890 and D21S1446. The results suggest that a U-type exchange occurred between the homologous distal 21q regions duplicated on the der(21) chromosome, leading to the r(21) formation. This is a novel mechanism put forward for the formation of a monocentric ring chromosome. © 2002 Wiley-Liss, Inc.

Microdissection and reverse painting reveals a microdeletion 6(q26qter) in a de novo r(6) chromosome.

Abstract: Ring chromosomes 6 are rare constitutional abnormalities with inconsistent phenotypic and clinical features. One of the reasons for this variability is the cytogenetically undetectable loss of chromosomal material from the telomeric segments at 6p or 6q. We have therefore used fluorescence in situ hybridization (FISH) to analyse a ring chromosome 6 that was detected in a newborn boy with dysmorphic features. Reverse painting of the microdissected ring chromosome onto normal metaphase spreads revealed a small deletion of the terminal region of the long arm, 6(q26qter). Moreover, the simple all-telomeric sequence (TTAGG)n was lost, whereas the p-specific subtelomeric sequence was still present. Our findings confirm that microdeletions occur during the formation of r(6) chromosomes and, therefore, are an important determinator of the associated phenotype.

Kabuki Make-up (Niikawa-Kuroki) Syndrome with Mosaicism Ring Chromosome X and Incomplete XIST Gene Expression

Abstract: Kabuki make-up syndrome (Niikawa-Kuroki syndrome) is a rare congenital disorder of unknown etiology characterized by a dysmorphic face, postnatal growth retardation, skeletal abnormalities, mental retardation, and unusual dermatologic patterns. The latter include long palpebral fissures, broad eye brows sparse in the lateral half, prominent eyelashes, lower lateral palpebral ertropia, and depressed nasal tips. We describe a 13-year-old girl with short stature, delayed puberty, mental retardation, and typical face characteristics of Kabuki make-up syndrome. High-resolution banding chromosome analysis revealed a mos 45,X/46,X,r(X) karyotype. Fluorescence in situ hybridization detected a positive XIST gene signal. XIST expression was demonstrated by reverse transcription polymerase chain reaction using primers spanning exons 2, 3, 4, 5 in RNA prepared from lymphocytes. To our knowledge, this is the first description of Kabuki syndrome manifestation with r(X) and XIST expression in Taiwan.

Two forms of ring 13 in a child with rhabdomyosarcoma.

Abstract: Mosaicism for two forms of ring 13 was found in a child with embryonal rhabdomyo-sarcoma of the bladder, minor anomalies, and developmental delay. Her chromosome constitution was 46, XX, r(13)(p11q34)/46, XX, r del(13)(p11q14). Both cell lines were present in lymphocytes and fibroblasts. The cell line with the smaller ring chromosome predominated in both tissues. The child's manifestations reflect the presence of both cell lines.