| 1. |
- Gisselsson Nord, David, et al.
(författare)
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Hibernomas are characterized by homozygous deletions in the multiple endocrine neoplasia type I region. Metaphase fluorescence in situ hybridization reveals complex rearrangements not detected by conventional cytogenetics
- 1999
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Ingår i: American Journal of Pathology. - 1525-2191. ; 155:1, s. 61-66
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Tidskriftsartikel (refereegranskat)abstract
- Hibernomas are benign tumors of brown fat, frequently characterized by aberrations of chromosome band 11q13. In this study, the chromosome 11 changes in five hibernomas were analyzed in detail by metaphase fluorescence in situ hybridization. In all cases, complex rearrangements leading to loss of chromosome 11 material were found. Deletions were present not only in those chromosomes that were shown to be rearranged by G-banding, but in four cases also in the ostensibly normal homologues, resulting in homozygous loss of several loci. Among these, the gene for multiple endocrine neoplasia type I (MEN1) was most frequently deleted. In addition to the MEN1 deletions, heterozygous loss of a second region, approximately 3 Mb distal to MEN1, was found in all five cases, adding to previous evidence for a second tumor suppressor locus in 11q13.
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| 2. |
- Gisselsson Nord, David, et al.
(författare)
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The structure and dynamics of ring chromosomes in human neoplastic and non-neoplastic cells
- 1999
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Ingår i: Human Genetics. - : Springer Science and Business Media LLC. - 1432-1203 .- 0340-6717. ; 104:4, s. 315-325
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Tidskriftsartikel (refereegranskat)abstract
- Acquired ring chromosomes have been found in most types of human neoplasia, with a frequency approaching 10% in malignant mesenchymal tumours. In this study, the composition and dynamics of ring chromosomes were analysed in eight cases of acute myelogenous leukaemia, 17 solid tumours, and five cases with constitutional rings. Chromosomal banding and fluorescence in situ hybridisation were performed to determine the content and the structural heterogeneity of the rings. Telomeric repeats were detected using peptide nucleic acid probes or primed in situ labelling, whereas centromeric activity was evaluated by detection of kinetochore proteins. Mitotic instability was assessed by the frequency of anaphase bridges. The results suggest that human ring chromosomes can be structurally and functionally divided into two categories. In the first of these, size variation is minimal and rearrangement at cell division is uncommon. The majority of such rings contain subtelomeric sequences. Constitutional ring chromosomes and most rings in leukaemias belong to this group, whereas only a few mesenchymal tumours exhibit rings of this type. The second category consists of rings with amplified sequences, primarily from chromosome 12, characteristically occurring in atypical lipomatous tumours and other subtypes of low or borderline malignant mesenchymal neoplasms. Variation in size and number is extensive, and breakage-fusion-bridge events occur at a high frequency. Abnormalities in pericentromeric sequences are common and, in some cases, kinetochores assemble in the absence of alphoid DNA. We conclude that it is not only the ring structure per se or the neoplastic nature of the host cell that determines ring instability, but probably also the functional role of the genes carried in the ring.
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