title: Position effect modifying gene expression in a patient with ring chromosome 14.
abstract: The clinical phenotype of patients with ring chromosomes usually reflects the loss of genomic material during ring formation. However, phenotypic alterations can also be found in the presence of complete ring chromosomes, in which the breakage and rejoining in terminal regions of both chromosome arms result in no gene loss. Here, we present a patient with a ring chromosome 14 that lost nothing but the telomeres. Since he and other patients with a similar chromosome abnormality present certain abnormal characteristics, we investigated the gene expression of eight chromosome 14 genes to find out whether the configuration of the ring had changed it, possibly producing some of these clinical features. The expression of these eight genes was studied by quantitative real-time polymerase chain reaction (qPCR) in the patient and in seven controls matched for gender and age. Two of them were found to be downregulated in the patient compared to the controls, indicating that his phenotype might be related to alterations in the expression of genes located in the abnormal chromosome, even when the copy number is normal. Thus, the phenotypic alterations found in the presence of complete ring chromosomes may be related to changes in the chromatin architecture, bringing about a change of expression by position effect. These results may explain some of the characteristics presented by our patient.
authors: Department of Morphology and Genetics, Universidade Federal de São Paulo, Rua Botucatu, 740, 04023-900, São Paulo, Brazil.
authors: Roberta Santos
authors: RS
authors: Guilherme
authors: Department of Morphology and Genetics, Universidade Federal de São Paulo, Rua Botucatu, 740, 04023-900, São Paulo, Brazil.
authors: Mariana
authors: M
authors: Moysés-Oliveira
authors: Department of Morphology and Genetics, Universidade Federal de São Paulo, Rua Botucatu, 740, 04023-900, São Paulo, Brazil.
authors: Anelisa Gollo
authors: AG
authors: Dantas
authors: Department of Morphology and Genetics, Universidade Federal de São Paulo, Rua Botucatu, 740, 04023-900, São Paulo, Brazil.
authors: Vera Ayres
authors: VA
authors: Meloni
authors: Department of Morphology and Genetics, Universidade Federal de São Paulo, Rua Botucatu, 740, 04023-900, São Paulo, Brazil.
authors: Mileny Esbravatti
authors: ME
authors: Colovati
authors: Department of Pathology, Laboratório de Citogenômica, Universidade de São Paulo, Avenida Dr. Eneas Carvalho de Aguiar 647, 05403-000, São Paulo, Brazil.
authors: Leslie Domenici
authors: LD
authors: Kulikowski
authors: Department of Morphology and Genetics, Universidade Federal de São Paulo, Rua Botucatu, 740, 04023-900, São Paulo, Brazil. melaragno.maria@unifesp.br.
authors: Maria Isabel
authors: MI
authors: Melaragno
mesh_terms: D000328:Adult; D002874:Chromosome Mapping; D002883:Chromosomes, Human, Pair 14 / Q000235:genetics; D015870:Gene Expression; D006801:Humans; D008297:Male; D010641:Phenotype; D060888:Real-Time Polymerase Chain Reaction; D012303:Ring Chromosomes; D016615:Telomere / Q000235:genetics*
keywords: Gene expression; Ring chromosome; qPCR and clinical phenotype