UMLS:C0023467 - FACTA Search

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Query: UMLS:C0023467 (acute myeloid leukemia)
35,200 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The nonrandom chromosomal translocation t(8;21)(q22;q22) can be found frequently in acute myelogenous leukemia with maturation (AML-M2). The breakpoint of this translocation has been cloned and characterized, and fusion transcript AML1/ETO has been identified. Reverse transcription polymerase chain reaction (RT-PCR) can be used to amplify the breakpoint site of AML1/ETO in t(8;21)-positive AML-M2 patients. The chimeric transcript can be detected in all 16 (100%) t(8;21)-positive AML-M2 patients. In all samples, the size of the amplified DNA fragments and pattern of restriction digest were identical, indicating that the t(8;21) translocation breakpoint occurs within a single intron of the AML1 and ETO genes. Interestingly, this fusion transcript was also detected in one of 13 AML-M2 patients without the t(8;21) translocation, indicating that a masked translocation involving chromosomes 8 and 21, exists in AML. Minimal residual disease was detected by semi-nested RT-PCR in all four patients tested, who had been in complete remission for 12, 15, 34, and 52 months, respectively. These results indicate that RT-PCR amplification of the AML1/ETO fusion transcript is a powerful tool for diagnosing and monitoring minimal residual disease in AML-M2 patients.
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PMID:Detection of AML1/ETO fusion transcript as a tool for diagnosing t(8;21) positive acute myelogenous leukemia. 750 93

The chromosomal translocation t(8;21)(q22;q22) in acute myeloid leukemia (AML) can be detected by a reverse transcription-polymerase chain reaction (RT-PCR) for the chimeric AML1/ETO transcript. We have evaluated the clinical relevance of this method for monitoring and detection of minimal residual disease (MRD) in seven patients who reached a complete hematological remission (CHR) after chemotherapy or autologous bone marrow transplantation (ABMT). Peripheral blood (PB) samples of five patients in first continuous complete remission (CCR) were still PCR-positive at a frequency of 1 in 10(5) cells after 7, 8, 8, 10 or 66 months. Chemotherapy led to a reduction from first- to second-step PCR-positivity in three serially monitored patients. AML1/ETO mRNA was also detected in the PB of two patients in CCR, 10 or 12 months after ABMT. PB and bone marrow (BM) showed identical results in all samples tested simultaneously. AML1/ETO fusion transcripts were neither found in the PB and BM of a healthy individual, nor in the PB of a patient after allogeneic BMT for cytogenetically proven t(8;21)-leukemia. Our results indicate the presence of cells carrying the AML1/ETO rearrangement in the PB and BM of all patients in CHR after chemotherapy or ABMT for t(8;21)-positive AML. While this finding raises interesting questions about the biology of acute leukemia, it limits the value of the AML/ETO RT-PCR for the prediction of impending relapse.
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PMID:AML1/ETO fusion mRNA can be detected in remission blood samples of all patients with t(8;21) acute myeloid leukemia after chemotherapy or autologous bone marrow transplantation. 751 42

The 8;21 chromosomal translocation involves the AML1 gene on chromosome 21 and the ETO gene on chromosome 8 and results in the transcription of a chimeric message. This translocation is most often associated with acute myelogenous leukemia with maturation (AML-M2). The leukemic cells of patients carrying t(8;21) often exhibit several characteristic morphologic features. We identified four cases in which the morphology led us to suspect a t(8;21), but in which this translocation was not observed by cytogenetic analysis. In two of the four cases, an AML1/ETO chimeric fragment was detected by reverse transcription and polymerase chain reaction (RT-PCR), and its sequence was found to be identical to that from patients with a cytogenetically proved t(8;21). Marrow specimens of the four patients lacking the t(8;21) cytogenetically were reviewed retrospectively with regard to seven morphologic features commonly reported to be associated with this translocation, and the results were compared to 13 morphologic controls with the t(8;21). Although none of the 13 controls had all of the characteristic morphologic features, all had at least six, as did the two t(8;21)-negative but RT-PCR-positive patients. The two patients who lacked the t(8;21) and who were RT-PCR-negative showed only three and four of these morphologic features, respectively. Both of the RT-PCR-positive patients had deletions of the long arm of chromosome 9, a common change associated with a t(8;21), supporting our assessment of these patients as having a cytogenetically undetected t(8;21).
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PMID:Correlation between cell morphology and expression of the AML1/ETO chimeric transcript in patients with acute myeloid leukemia without the t(8;21). 752 91

Patients with acute myeloid leukaemia with maturation (AML-M2) that carried the t(8;21) were tested for the presence of chimeric AML1/ETO mRNA. After RT-PCR, an expected band of 208 bp was observed on gel, as well as some slower migrating bands. The base composition of one of the additional products was determined and was found to contain a new 68-bp ETO sequence present at the fusion of AML1 and ETO genes. The derived protein sequence results in a truncated AML1 gene still containing the putative DNA binding domain. Molecular diversity in the AML1-ETO transcripts will have consequences for the detection of minimal residual disease and antisense studies.
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PMID:Molecular diversity in AML1/ETO fusion transcripts in patients with t(8;21) positive acute myeloid leukaemia. 752 1

The t(3;21)(q26;q22) is associated with chronic myelogenous leukemia in blast crisis (CML-BC), leukemia evolving from (therapy-related) myelodysplasia, and with leukemia following other hematopoietic proliferative diseases. Molecular cytogenetic analysis and cloning of a few t(3;21) cases indicate that the breakpoints are quite heterogeneous even within a specific clinical phenotype. Interestingly some of the (3;21) breakpoints involve the AML1 gene previously found rearranged in the t(8;21) associated with acute myelogenous leukemia. AML1 is related to the Drosophila gene runt and is the human counterpart of the gene for the alpha subunit of the nuclear polyoma enhancer binding protein (PEBP2) also known as the core binding factor (CBF). In the t(3;21) AML1 was found rearranged with EAP, a gene on chromosome 3 encoding a small ribosomal protein, as well as with EV11, another gene on chromosome 3. Here we report our study of six cases of t(3;21). By using fluorescence in situ hybridization (FISH) analysis and AML1 probes we could conclude that at least in two CML-BC cases the breakpoint occurred in the AML1 intron that is disrupted by the t(8;21). An AML1/EAP fusion transcript, different from the one described in a therapy-related myelodysplasia, was detected in both CML-BC cases. This transcript is expected to result in a predicted protein containing the AML1 nuclear binding domain with an attached stretch of 17 amino acids unrelated to the EAP small ribosomal protein. In the other t(3;21) patients we could not detect an AML1/EAP transcript or an AML1/EV11 transcript. This result suggests heterogeneity of the t(3;21) at the molecular level. The AML1 chimeric transcripts identified so far, both in the t(3;21) and in the t(8;21), diverge from the normal transcripts either after exon 5 or exon 6. Here we show that in normal AML1 transcripts different splicing events are seen to occur after AML1 exon 5 as well as exon 6.
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PMID:AML1 fusion transcripts in t(3;21) positive leukemia: evidence of molecular heterogeneity and usage of splicing sites frequently involved in the generation of normal AML1 transcripts. 753 26

The t(8;21) reciprocal chromosomal translocation is frequently associated with M2b type of acute myeloid leukemia (AML). Recently, two genes, MTG8 on chromosome 8 and AML1 on chromosome 21, were found. The t(8;21) translocation resulted in rearrangements of the two genes and formation of AML1/MTG8 fusion gene. To clarify the molecular characteristics of AML-M2b, we studied 41 patients with AML-M2b. By Southern blot and hybridization, the rearrangements of AML1 and MTG8 genes were detected in 24 of 30 and 22 of 28 patients, respectively. By means of reverse transcription and polymerase chain reaction (RT-PCR), the AML1/MTG8 chimeric transcript was found in all 37 patients. In 4 patients with AML-M2b of normal karyotype, AML1/MTG8 fusion mRNA and/or rearrangements of AML1 and MTG8 genes were detected. However, among 31 patients with other types of AML, these abnormalities were found in only one patient with AML-M6. These results suggest that rearrangements of AML1, MTG8 genes and/or AML1/MTG8 fusion gene could be regarded as gene marker of AML-M2b that can be applied in the diagnosis and monitoring of therapy and minimal residual disease.
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PMID:[Rearrangements and fusion gene of AML1 and MTG8 in acute myeloid leukemia M2b]. 755 57

There is compelling evidence that leukemia arises via a multistep process. Molecular analysis of human leukemias, which are typically clonal, commonly shows multiple genetic lesions in a single leukemia including chromosomal translocations, gene amplification, and point mutations, and in several cases the mutational activation of an oncogene and the loss of a tumor suppressor gene have been found in the same leukemic cell. Accumulative evidences suggest that a number of oncogenes and tumor suppressor genes are involved in the hematopoietic tumorigenesis. These mutations can be utilized for molecular diagnosis of human hematopoietic tumors. Among them, detection of chimeric gene generated by chromosomal translocation is especially useful for molecular diagnosis. The t(3;21) (q26;q22) translocation is found usually in blastic crisis of CML and leukemias developed from MDS or hematopoietic proliferative diseases, but never in de novo acute myelocytic leukemia. This raises the possibility that the molecular event underlying the t(3;21) translocation has a critical role in progression from a preleukemic state to a leukemic state. The generation of AML1/EVI-1 chimeric gene has been demonstrated to be consistent in t(3;21)-carrying leukemias. Although target genes remain to be elucidated for both AML1 and EVI-1 as transcription factors, the AML1/EVI-1 fusion protein could work on different set of genes critical to the process of proliferation and differentiation of hematopoietic cells.
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PMID:[Diagnosis of hematological disorders by mutational analysis of oncogenes]. 760 95

PEBP2/CBF is a heterodimeric transcription factor composed of alpha and beta subunits. Previously, we reported two distinct mouse genes, PEBP2 alpha A and PEBP2 alpha B, which encode the alpha subunit. PEBP2 alpha B is the homologue of human AML1, encoding the acute myeloid leukemia 1 protein. AML1 and human PEBP2/CBF beta were detected independently at the breakpoints of two characteristic chromosome translocations observed frequently in two subtypes of acute myeloid leukemia. The PEBP2 alpha proteins contain a 128-amino-acid (aa) region highly homologous to the Drosophila melanogaster segmentation gene runt. The evolutionarily conserved region, named the Runt domain, harbors DNA-binding and heterodimerizing activities. In this study, we identified the third Runt-domain-encoding gene, PEBP2 alpha C, which maps to 1p36.11-p36.13 in the human chromosome and encodes a 415-aa protein. PEBP2 alpha C forms a heterodimer with PEBP2 beta, binds to the PEBP2 site and transactivates transcription, similar to PEBP2 alpha A and PEBP2 alpha B.
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PMID:Cloning, mapping and expression of PEBP2 alpha C, a third gene encoding the mammalian Runt domain. 762 58

The t(8;21) is a frequent chromosome abnormality in acute myeloid leukemia (AML), particularly associated with M2 of the French-American-British (FAB) classification, but also found in a few patients with myelodysplastic syndrome (MDS). The two genes involved in the t(8;21) have been recently isolated and the cDNA of the AML1/ETO fusion gene identified. We have investigated a series of AML and MDS patients by a reverse transcriptase-polymerase chain reaction (RT-PCR) and analyzed the clinical and laboratory features of leukemia with t(8;21). The t(8;21) was only found in a subset of M2, which had the clinical and hematological features distinct from those M2 without t(8;21). M2 with t(8;21) was associated with a significantly higher myeloid differentiation and with a good response to chemotherapy. Moreover, among the patients with refractory anemia with excess of blasts in transformation (RAEB-T) the t(8;21) was also significantly associated with a higher myeloid differentiation and a good response to chemotherapy. M2 patients with t(8;21) could be distinguished on a number of hematological parameters, eg white blood cell count and percentage of bone marrow myeloblasts and promyelocytes, from RAEB-T carrying the t(8;21). Based on these findings we suggest that leukemia patients carrying t(8;21) can be grouped into two types; overt acute myeloid leukemia (M2) and smoldering or slowly evolving myeloid leukemia.
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PMID:High degree of myeloid differentiation and granulocytosis is associated with t(8;21) smoldering leukemia. 763 Jan 88

The WT 1 gene has been isolated as a tumor suppressor gene of Wilms' tumor. Using reverse transcriptase-polymerase chain reaction (RT-PCR), relative levels of the WT 1 gene expression was examined in 87 patients with acute leukemia, 25 with chronic myelogenous leukemia (CML), and 24 with non-Hodgkin's lymphoma (NHL). Significant levels of the WT 1 gene were expressed in all leukemia patients, and for CML the levels increased as the clinical phase progressed. No point mutations were found in the WT 1 gene when samples from 15 acute leukemia patients were subjected to PCR single-strand conformation polymorphism analysis. In striking contrast to acute leukemia, the levels of WT1 gene expression for NHL were significantly low or even undetectable. The levels of WT 1 gene expression inversely correlated with the prognosis of acute leukemia. The quantification of the WT 1 gene expression made it possible to detect minimal residual disease (MRD) in acute leukemia regardless of the presence of absence of tumor-specific DNA markers. Simultaneous monitoring of MRD by RT-PCR using primers for specific DNA markers in four patients (two AML-M3 with PML/RAR-alpha, one AML-M2 with AML1/ETO, and one CML with bcr/abl) detected MRD comparable to that obtained from quantitation of WT 1 gene expression. In a patient with acute promyelocytic leukemia, the limits of leukemic cell detection by RT-PCR using either WT 1 or PML/RAR-alpha gene primers were 10(-3)-10(-4) and 10(-4) for bone marrow, and 10(-5) and 10(-4) for peripheral blood, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[WT 1 and leukemia]. 764 50

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