An unstable giant satellite associated with chromosomes 21 and 22 in the same individual.
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The short arms of the acrocentric chromosomes are among the most common sites in which to find human chromosomal heteromorphisms. Heteromorphic chromosomes are noted for their variability between individuals and populations; however, they generally are consistent within an individual. Contrary to this general rule, a normal female was found to have a giant satellite on the short arm of a chromosome 22 in most lymphocytes and fibroblasts, but in other cells, it was attached to a chromosome 21. Furthermore, in some cells, it was found on multiple chromosomes, that is, on both 22's or on a 21 and a 22. The familial nature of this heteromorphism was established when it was found in the woman's mother, where it was confined exclusively to chromosome 22. These results suggest an unstable giant satellite associated with both G-group chromosomes of a normal individual. Results are discussed in the light of the patient's occupational exposure to insecticides at a mushroom farm. (+info)
bcr Rearrangement without juxtaposition of c-abl in chronic myelocytic leukemia.
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Southern blot analysis detected a bcr gene rearrangement within leukemic cells of a Philadelphia chromosome-negative chronic myelocytic leukemia (CML) patient that led to transcription of a novel 7.3 kb bcr RNA species. Participation of the c-abl oncogene in this genomic recombination could be ruled out by in situ hybridization studies and Northern blot analysis. (+info)
Increased expression of a novel c-abl-related RNA in K562 cells.
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The c-abl locus is translocated from chromosome 9 to chromosome 22 in chronic myelogenous leukemia (CML), creating the Philadelphia chromosome (22q-, Ph1), one of the most consistent chromosomal abnormalities found in human hematologic malignancy. The K562 cell line is a human cell line originally derived from a patient with CML. We have isolated cloned human c-abl probes to analyze the organization and expression of abl genes in patients with CML and in K562 cells. With these probes, we confirm the amplification of abl genes in K562 cells. In addition, we demonstrate the presence of increased amounts of a novel RNA species hybridizing to a c-abl probe in K562 cells. This same large RNA species is present in addition to two normal transcripts in the leukemic cells of patients with CML. These results provide evidence that the c-abl locus is abnormally expressed in CML. (+info)
Preferentially expressed genes in chronic myelogenous leukemia.
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The predominant circulating cells in chronic myelogenous leukemia (CML) morphologically resemble normal myeloid precursors; however, certain characteristics indicate the two are not identical. Approximately 88% of the patients with clinically typical CML present with a cytogenetic abnormality known as the Philadelphia chromosome (Ph1). Additionally, the leukocyte alkaline phosphatase (LAP) value is decreased in CML. To investigate if there are selected genes expressed in the CML cell population, poly(A+)RNA from a chronic-phase, Ph1-positive CML patient was used for construction of a complementary DNA (cDNA) library. Recombinant clones representing moderately to abundantly transcribed sequences were selected by annealing [32P]-cDNA transcribed from homologous RNA to the library sequences and assessing radioactivity in the hybrids. From an initial 729 colonies, 417 (57.2%) displayed a hybridization signal more intense than controls, indicating these recombinant plasmids contained sequences homologous to moderately or highly expressed RNAs from this particular patient. Screening of the 417 clones--utilizing 32P-cDNAs derived from normal human placenta, an acute myelomonocytic leukemia (AMML), and two other CML samples--was used to select clones likely to represent sequences preferentially expressed in CML. Sixteen recombinants were initially selected that repeatedly failed to display hybridization with the placenta and AMML-derived probes. Further analysis of eight of these clones indicated that six contain sequences preferentially expressed in CML. One clone, C-A3, has been studied with 63 different RNA samples. This sequence is found to be highly expressed in peripheral blood cells from the chronic phase of both Ph1-positive and Ph1-negative CML as well as in a Ph1-positive acute myelogenous leukemia (AML). Expression is reduced in lymphoblastic crisis of CML (L BC-CML) and essentially absent in myeloblastic crisis of CML (M BC-CML). While preliminary, the results suggest that this probe may be useful as an aid in diagnosing Ph1-negative CML and in distinguishing M BC-CML from L BC-CML and Ph1-positive AML. (+info)
Ph1-positive acute lymphocytic leukemia with chromosome 7 abnormalities.
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A 56-yr-old woman with acute lymphocytic leukemia showed the presence of a Philadelphia chromosome in 90% of the bone marrow metaphases and in 10% of the peripheral blood metaphases. Part of the long arm of a G22 chromsome was translocated to the long arm of a C9 chromosome. A second cytogenetic abnormality was found in chromosome 7. Monosomy 7 was found in 60% of the marrow and in 20% of the peripheral blood metaphases. Chromosome 7q- was also found in a small percentage of the metaphases examined. Three months later, when the patient was in partial remission, only 10% of the marrow cells showed chromosome 7 monosomy and a Ph1 chromosome. During complete remission, no chromosomal abnormalities were found, except for a high breakage rate. The finding of a Ph1 chromosome in acute lymphocytic leukemia indicates that different precursors, both granulocytic and lymphocytic, may be involved in the Ph1 process. (+info)
Myelomonocytic leukaemia with a preleukaemic syndrome and Ph1 chromosome in monozygotic twins.
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A case of monozygotic twins with a preleukaemic phase of 3 1/2 years is reported. The final haematological picture was that of myelomonocytic leukaemia. The karyotype investigated in one twin during the final period of the disease showed a Ph1 chromosome. (+info)
The Philadelphia chromosome in human macrophages.
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Three patients with chronic myelocytic leukemia in different phases of the natural history of the disease were studied. Their bone marrow cells were cultured under conditions favoring macrophage proliferation, and parallel cytogenetic and cytochemical studies were performed. All cell metaphases examined contained the Ph1 chromosome at a time when more than 80% of these metaphases were in identifiable macrophages. We conclude that the mononuclear phagocyte cell line contains the abnormal chromosome in Ph1-positive chronic myelocytic leukemia. (+info)
Characteristics of blast crisis in chronic granulocytic leukemia.
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The terminal phase of most patients with Ph1-positive chronic granulocytic leukemia (i.e., blast crisis) resembles acute leukemia. The clinical and hematologic features of blast crisis in 73 patients with chronic granulocytic leukemia have been reviewed. Two major morphological subgroups, lymphoblastic and myeloblastic, were identified. The lymphoblastic group in general had more profound thrombocytopenia and a greater number of blasts, while the myeloblastic group had more severa anemia. Extramedullary leukemia was documented in 27 patients. In 12 patients extramedullary leukemia preceded or occurred simultaneously with blast crisis in the bone marrow and peripheral blood. On the basis of this study we present hematologic criteria for the diagnosis of blast crisis and emphasize the importance of extramedullary leukemia in heralding the onset of blast crisis. (+info)