Cases reported "Chromosome Aberrations"

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1/272. Increased sister chromatid exchange in bone marrow and blood cells from Bloom's syndrome.

    Bone-marrow cells from a patient with Bloom's syndrome cultured for 48 h in the presence of BudR exhibited a striking increase in the number of sister chromatid exchanges (SCEs) in comparison to that in the marrow cells of a patient with treated polycythemia vera (PV). Thus, it appears that an increased incidence of SCE in Bloom's syndrome occurs in various differentiated types of cells, not just blood lymphocytes, and constitutes the syndrome's most characteristic cytogenetic feature. In contrast, the incidence of SCE was not increased in marrow cells and lymphocytes of the particular PV patient studied here, whose cells did exhibit increased numbers of chromatid and chromosome gaps and breaks, presumably as result of the patient's earlier treatment. An increased frequency of SCE was demonstrated in Bloom's syndrome lymphocytes using both a technique based on BudR incorporation and one based on labeling with tritated deoxycytidine. This observation constitutes evidence against the increase of SCE being due to an unusual reaction to BudR. By conventional cytogenetic techniques, chromosome instability, including chromatid and chromosome breaks, but no homologous chromatid interchanges were also recognized in Bloom's syndrome bone-marrow cells incubated in vitro (without BudR) for either 1.k or 16 h. This observation points to the existence of chromosome instability in vivo.
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ranking = 1
keywords = instability
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2/272. Familial cerebellar hypoplasia and pancytopenia without chromosomal breakages.

    Two siblings manifested a neuro-haematologic syndrome characterised by low birth weight, failure to thrive, chronic persistent tongue ulceration, severe truncal ataxia and pancytopenia without either telangiectasia or chromosomal instability. One sibling died from sepsis and the cerebellum demonstrated reduced cellularity of the molecular and granular layers with relative preservation of purkinje cells and minimal gliosis. A surviving sibling has shown haematologic progression to a myelodysplastic disorder. There was no evidence of any chromosomal instability following exposure of fibroblasts and lymphocytes to irradiation. monosomy-7 was not present in the surviving sibling. We suspect that these two patients represent another example of the rare Hoyeraal-Hreidarsson syndrome and we are currently engaged in very close monitoring of the surviving sibling for evidence of any karyotypic abnormality.
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ranking = 1
keywords = instability
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3/272. Chromosome instability in lymphocytes from two patients affected by three sequential primary cancers: the role of fragile sites.

    The chromosomal aberration rate and the expression of fragile sites induced by aphidicolin were evaluated in metaphase chromosomes obtained from peripheral blood lymphocytes of two untreated patients with multiple primary cancers. Spontaneous aberrations of chromosome number and structure and chromosome fragility were compared with controls with the use of the same methods. Chromosomal aberration rates and expression frequencies of fragile sites were significantly higher in the patients than in normal control subjects. In the patients, all but one structural chromosome aberration involved at least one fragile site. Our results suggest that fragile sites may be unstable regions of the human genome, which might play an important role in the genetic instability associated with cancer predisposition.
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ranking = 2.5
keywords = instability
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4/272. Mosaic tetrasomy 9p in a girl with multiple congenital anomalies: cytogenetic and molecular-cytogenetic studies.

    We report on a 16-year-old girl with tetrasomy 9p mosaicism. Clinical investigations disclosed a malformation syndrome with craniofacial abnormalities, dysplasia of the right clavicle, short neck with cervical ribs, patella dislocation, Dandy-Walker malformation, mental retardation and blindness. karyotype analysis of blood lymphocytes indicated an additional marker in the size of a C-group chromosome with a large heterochromatic block in 88% of the investigated metaphases. The origin and structure of this additional marker could not be determined by chromosome banding. Application of fluorescence in situ hybridisation and comparative genomic hybridisation identified the origin of the marker chromosome, demonstrating the effectiveness of molecular-cytogenetic investigations in the diagnosis of structural and numerical chromosome abnormalities.
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ranking = 1.229232372322
keywords = genomic
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5/272. Clonal analysis of a case of multifocal oesophageal (Barrett's) adenocarcinoma by comparative genomic hybridization.

    Oesophageal adenocarcinomas arising in Barrett's epithelium occasionally present as multiple lesions. This could be due to either a multifocal presentation of the same tumour, or different neoplasms arising simultaneously in a dysplastic Barrett's oesophagus ('field cancerization'). This is a report of the genetic analysis of multiple neoplastic sites in a Barrett's oesophagus with an extensive area of dysplasia. In addition, the dysplastic Barrett's epithelium was evaluated. For the genetic screening, comparative genomic hybridization (CGH) allowed evaluation of the whole genome of each specimen. Five cancerous regions were selected and subsequently dissected from paraffin-embedded tissue blocks. The use of archival materials enabled a targeted collection of representative tumour locations. Multiple genetic aberrations were detected by CGH in all cancer sites. Losses on 3p, 4, 7q, 18q, and Y, as well as gains on 8q, 9q, 12p, 13q, 17q, 20p and X, were found in each specimen. In four out of the five lesions, simultaneous losses on 9p, 15q, and 16q, with concomitant gains on 5p, 7q, and 10p, were disclosed by CGH. Adjacent high-grade dysplastic Barrett's mucosa shared the losses on 3p, 4, 7q, 9p, 18, and Y, as well as the gains on 5p, 7q, 13q, 17q, and X, thereby confirming its precursor status. Within this single and rare case of multifocal Barrett's adenocarcinoma, a monoclonal genotype was present. This must have been caused by an extensive outgrowth of a single tumour.
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ranking = 6.1461618616101
keywords = genomic
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6/272. Identification of amplified genes in a patient with acute myeloid leukemia and double minute chromosomes.

    A case of acute myeloid leukemia (M2) with double minute chromosomes and complex karyotypic abnormalities was analyzed cytogenetically and molecularly. comparative genomic hybridization (CGH) showed that the 8q24 region that contains the MYC oncogene was not amplified. Instead, amplification of chromosomal regions 11q23-->qter and 9p11-->pter was identified. Southern blot analysis confirmed the CGH findings and showed that the ETS1, FLI1, SRPR, NFRKB, and KCNJ5 genes located at 11q23-->24 were amplified, whereas the MLL at 11q23 was not amplified. Additionally, the IFN beta 1 and CDKN2A genes at 9p were amplified, but to a lesser degree. This is the first example of a case of acute myeloid leukemia with double minute chromosomes that has not involved amplification of either the MYC or the MLL genes.
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ranking = 1.229232372322
keywords = genomic
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7/272. Identification of a novel R642C mutation in Na/Cl cotransporter with Gitelman's syndrome.

    Gitelman's syndrome, a variant of Bartter's syndrome, is an inherited disorder characterized by hypokalemic metabolic alkalosis, hypomagnesemia, and hypocalciuria, and these abnormalities have recently been linked to the thiazide-sensitive Na/Cl cotransporter (TSC) gene. We evaluated three unrelated patients affected with this syndrome whose diagnosis was made based on clinical and biochemical features. The data of clearance studies in these patients were compatible with Gitelman's syndrome. We then investigated possible mutations of the TSC gene. In one patient whose parents are consanguineous, we identified a novel missense mutation in the TSC gene, which causes alteration of arginine to cysteine at codon 642 (R642C mutation) located in the cytoplasmic tail of the product. This mutation results in the loss of an MspI site in exon 15 of the TSC gene. MspI digestion analysis of genomic dna fragments from the family was consistent with the autosomal recessive inheritance of the disorder, and presence of this mutation correlated with the clinical manifestations. Such mutation was not detected in 47 normal healthy subjects. In the second patient, we found another missense mutation in one allele of the TSC gene, which results in alteration of arginine to glutamine at codon 955. In the third patient, no mutation causing amino acid substitution was found in the TSC gene. These results indicate that the R642C mutation in TSC is critically important for impairment of this cotransporter function and also suggest the necessity of further investigations in the genetic background of Gitelman's syndrome.
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ranking = 1.229232372322
keywords = genomic
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8/272. Multipaint FISH: a rapid and reliable way to define cryptic and complex abnormalities.

    We present the use of a multipaint fluorescence in situ hybridisation (FISH) approach for the detection and interpretation of chromosome abnormalities that could not be resolved by conventional cytogenetics alone. In case 1, a de novo add(Xp) was shown to be an unbalanced X;12 translocation; in case 2, a complex rearrangement involving a deletion of 5p was shown to include a previously undetected cryptic 5;6 translocation. In addition, in case 3, this technique defined additional complexities and nine breakpoints in an acquired rearrangement of chromosomes 2, 9, 11, 16 and 22 in a patient with myelodysplasia. The technique allows the simultaneous identification of up to 24 chromosomes on a single slide using FISH with directly labelled whole chromosome paints. This simple and rapid method does not require image enhancement, produces results within 48 h and, therefore, offers an alternative to other recent developments, such as combinatorial multifluor FISH, spectral karyotyping or comparative genomic hybridisation.
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ranking = 1.229232372322
keywords = genomic
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9/272. Multiple chromosomal associations and paracentromeric region instability in a case of acute leukemia.

    A case of acute myelomonocytic leukema is described, which was characterized cytogenetically by the presence of centromeric elongations, somatic crossovers, selective endoreduplication figures, and multiple chromosomal clusters. The demonstration of these phenomena by selective staining techniques for the chromosome bands (Q, C, G and S) and the nucleolar areas (acridine-orange, amido black B 10) raises some biological aspects involved in the proliferation of leukemic cells, such as nucleolar persistance during the metaphase and the non-separation of chromatids in the clusters during the anaphase. These structural abnormalities may represent the background for the explanation of the appearance of subclones in neoplastic disorders.
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ranking = 2
keywords = instability
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10/272. Complex karyotype and N-RAS point mutation in a case of acute megakaryoblastic leukemia (M7) following a myelodysplastic syndrome.

    The development of acute megakaryoblastic leukemia (ANLL-M7) following myelodysplastic syndrome (MDS) has been described only in a few reports, and the mutations necessary for this transformation are still unknown. In this study, we describe a case of ANLL-M7 with a previous history of MDS presenting a complex karyotype 46,XX, t(4;11)(q21;q23),del(5)(q13q33),t(12;13)(p13;q21) and N-RAS point mutation. During MDS, the patient showed a hypercellular myelogram with dysplasia of the three myeloid lineages and the clinical symptoms characteristic of the 5q- syndrome. During the follow-up, we observed the appearance of two additional subclones, one with an isochromosome 17q and another with polyploidy. The presence of an isochromosome 17q in one subclone and polyploidy in another is probably due to the genetic instability generated by the malignant transformation.
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ranking = 0.5
keywords = instability
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