1/9. Acral myxoinflammatory fibroblastic sarcoma with unique clonal chromosomal changes.Acral myxoinflammatory fibroblastic sarcoma is a rare tumor of the distal extremities. We present the hitherto unreported karyotypic abnormalities of this new entity. The tumor presented as a mass in the dorsum of the foot in a 53-year-old woman and showed the typical virocyte-like and lipoblast-like cells in a myxoid and inflammatory background. cytogenetic analysis revealed a complex karyotype with a reciprocal translocation t(1;10) (p22;q24) in addition to the loss of chromosomes 3 and 13. fluorescence in situ hybridization with the 769E11YAC and BAC 31L5 and 2H23 probes showed the breakpoint to be located proximally to BCL10 and distally to GOT1 genes on chromosomes 1p22 and 10q24, respectively. The presence of these clonal chromosomal changes supports the neoplastic nature of acral myxoinflammatory fibroblastic sarcoma and underscores that it represents a separate entity.- - - - - - - - - - ranking = 1keywords = hybridization (Clic here for more details about this article) |
2/9. Characterisation of a new rare fragile site easily confused with the fragile X.A new fragile site (FRAXE) in Xq28 is described. It appears to be a typical folate sensitive fragile site. The fragile site is not associated with mental retardation, it does not give abnormal results when subjected to Southern analysis with probe pfxa3 which detects the unstable DNA sequence characteristic of fragile x syndrome. in situ hybridization mapping locates the fragile site between 150 kb and 600 kb distal to FRAXA. The distinction between the two fragile sites is important clinically since cytogenetic detection of FRAXE, without molecular analysis, could result in misdiagnosis of fragile x syndrome.- - - - - - - - - - ranking = 1keywords = hybridization (Clic here for more details about this article) |
3/9. Use of fluorescence in situ hybridization to confirm the interpretation of a balanced complex chromosome rearrangement ascertained through prenatal diagnosis.A balanced complex chromosome rearrangement (BCCR) involving 3 chromosomes with 4 breakpoints, was identified in a 36-yr-old woman who was studied because her fetus was discovered to have an unbalanced reciprocal translocation (7q;10q). Analysis of high resolution bands and the application of fluorescence in situ hybridization has identified the BCCR as der(7)t(7;10)(q21.13;q23.33)ins(21;7)(q21.3;q11.22q21.13), der(10)t(7;10)(q21.13; q23.33), der(21)ins(21;7)(q21.3;q11.22q21.13). Alternate segregation of the BCCR appears to be favoured, and has resulted in two pregnancies with an unbalanced chromosome constitution.- - - - - - - - - - ranking = 5keywords = hybridization (Clic here for more details about this article) |
4/9. fluorescence in situ hybridization provides evidence for two-step rearrangement in a masked Ph chromosome formation.A chronic myelogenous leukemia (CML) patient with a masked Ph chromosome due to the translocation (9;10;22)(q34;q24;q11) is reported. Banding analysis showed a 9q chromosome typical of standard t(9;22)(q34;q11), and fluorescence in situ hybridization studies confirmed the involvement of a chromosome 10 in the masked Ph formation and also the presence of 3' ABL-DNA sequences in the der(22). This complex rearrangement could be explained by two consecutive translocations: the first, a standard t(9;22) (q34;q11), the second, a translocation between a chromosome 10 and the der(22) with a breakpoint in sequences derived from chromosome 9 telomeric to the ABL gene. By reverse transcription polymerase chain reaction (RT-PCR), we studied the BCR/ABL transcript junction: a chimeric m-rna b3-a2, indicating a breakpoint within the major breakpoint cluster region, was found.- - - - - - - - - - ranking = 5keywords = hybridization (Clic here for more details about this article) |
5/9. Fragile site and interstitial telomere repeat sequences at the fusion point of a de novo (Y;13) translocation.We describe a novel fragile site in a rearranged chromosome, associated with the presence of telomeric repeat sequences at the fusion point of a translocation between chromosomes 13 and Y. The case reported in this study shows a de novo (Y;13) translocation, which appears to represent fusion of an apparently intact chromosome Y with a chromosome 13 that has lost only part of its short arm. Ten percent of the cells show a normal karyotype without the (Y;13) translocation. Molecular cytogenetic studies of the derived Y;13 chromosome revealed three hybridization sites of the telomeric probes-one at each end and one at the breakpoint junction. A fragile site is also observed in the intrachromosomic telomeric region. This coincidence suggests that the telomere repeat sequences (TTAGGG)n, when present at an interstitial chromosomal location, can promote the formation of a novel fragile site.- - - - - - - - - - ranking = 1keywords = hybridization (Clic here for more details about this article) |
6/9. Prenatal identification of i(Yp) by molecular cytogenetic analysis.An i(Yp) is a rare marker chromosome. We present a case of de novo 46,X,i(Yp) detected prenatally in an amniotic fluid specimen. fluorescence in situ hybridization (FISH) studies using a panel of Y-specific biotinylated dna probes identified the marker chromosome as i(Yp). comparative genomic hybridization (CGH) studies further confirmed the diagnosis. Upon pregnancy termination, external examination of the fetus revealed a generally well-developed male fetus with slight facial dysmorphism and prominent rocker-bottom feet. The molecular cytogenetic data in this case proved very useful in genetic counselling and served as a good example illustrating the important role of molecular techniques for accurate identification of marker chromosomes.- - - - - - - - - - ranking = 2keywords = hybridization (Clic here for more details about this article) |
7/9. Expression of three rare fragile sites: chromosomal truncation, amplification of distal segment and telomeric renewal.fluorescence in situ hybridization with a telomeric probe was used to monitor telomeric renewal following breakage induced by the rare fragile sites FRA10A, FRA12A and FRA16B. Interstitial telomere-like sequences were detected only at the break sites of FRA10A.- - - - - - - - - - ranking = 1keywords = hybridization (Clic here for more details about this article) |
8/9. Most Jacobsen syndrome deletion breakpoints occur distal to FRA11B.Recent studies have identified a (CCG)n repeat in the 5' untranslated region of the CBL2 protooncogene (11q23.3) and have demonstrated that expansion of this repeat causes expression of the folate-sensitive fragile site FRA11B. It has also been demonstrated that FRA11B is the site of breakage in some cases of Jacobsen syndrome (JS) involving terminal deletions of chromosome 11q. We report on 2 patients with JS and a 46,XX,del(11)(q23.3) karyotype. In both cases, microsatellite and fluorescence in situ hybridization analyses indicated that the deletion breakpoint was approximately 1.5-3 Mb telomeric to FRA11B. There was no evidence of expansion of the CBL2 (CCG)n repeat in the parents of either patient. The deleted chromosome was of paternal origin in both cases, although it was of maternal origin in the cases reported to be caused by FRA11B. These findings and those in previously reported patients suggest that the breakpoint for most 11q deletions in JS patients is telomeric to FRA11B, which raises the possibility that there may be other fragile sites in 11q23.3 in addition to FRA11B. These findings also support previous evidence that there may be a propensity for breakpoints to differ depending on the parental origin of the deleted chromosome.- - - - - - - - - - ranking = 1keywords = hybridization (Clic here for more details about this article) |
9/9. Molecular analysis of 1p36 breakpoints in two Merkel cell carcinomas.Merkel cell carcinoma (MCC) is a rare aggressive neuroendocrine tumor of the skin. Only little information is available on the genetic alterations occurring in this tumor. Cytogenetic studies thus far have not shown recurrent chromosomal changes, although various structural chromosome 1 rearrangements, including deletions, often leading to loss of distal 1p material appear to be frequent. We report on fluorescence in situ hybridization and loss of heterozygosity analyses of an MCC tumor and MCC cell line UISO. The present study has shown that two distinct regions in the most distal band 1p36 on the short arm of chromosome 1 can be implicated in MCC. One region at 1p36.3 was delineated by a distal deletion in the MCC tumor as a result of an unbalanced translocation, resulting in loss of all markers distal to ENO1. This region was previously shown to be deleted in different tumor types including neuroblastoma. In cell line UISO an insertion in 1p36.2 was identified. The insertion breakpoint indicates a second, more proximal, region on 1p involved in MCC. The insertion breakpoint was mapped within a cluster of repetitive tRNA and snRNA genes and thus could coincide with the constitutional 1p36 breakpoint previously reported in a patient with neuroblastoma.- - - - - - - - - - ranking = 1keywords = hybridization (Clic here for more details about this article) |