Presence of telomeric and subtelomeric sequences at the fusion points of ring chromosomes indicates that the ring syndrome is caused by ring instability

摘要: In situ hybridization of a telomeric (TTA-GGG)n sequence to metaphases from three cases ring chromosome, involving respectively chromosomes 4, 16, and 20, showed the presence cognate sequences in all rings. To investigate whether these originated by telomere-telomere fusion, we determined, hybridization, telomere-associated and/or specific distal were still present chromosomes. The finding that preserved strongly indicates they fusion. All subjects carrying are affected so-called syndrome, with failure thrive, minor dysmorphic signs no major anomalies. r(4) patient has mosaic form normal cell line intelligence. r(16) r(20) patients have moderate mental retardation suffer seizures. We conclude even its more severe manifestation, is caused chromosome instability.