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Query: UMLS:C0023418 (leukemia)
 93,477 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cytogenetic and fluorescence in situ hybridization studies have shown the presence of telomeric repeats in translocation present in three patients with hematopoietic malignancies. One had jumping translocations, involving 1q12 and 2q, 16p, and 19q. These sequences were detected by FISH only in derivative chromosomes t(1;16) and t(1;19) in the first patient, and t(1;7) in the second. They were not seen in derivative t(1;2) and t(7;8), respectively. Interstitial telomeric sequences were observed in der(2)t(1;2) in about half of the metaphases in the third patient. The instability of interstitial telomeric DNA repeats in translocations is shown by the present findings. Moreover it supports the hypothesis that the presence of interstitial telomere repeats is not sufficient to make it functional.
Leukemia 2000 Sep
PMID:Interstitial telomere repeats in translocations of hematopoietic disorders. 1099 10

Cytogenetic study of a young child with acute megakaryocytic leukaemia (AML-M7) has shown a karyotype with 49-50 chromosomes with one and two acquired extra chromosomes 21. Fluorescence in situ hybridization detected a minor clone with translocation t(1;21) and loss of a part of chromosome band 1p36. Trisomy and polysomy 21 are not uncommon in AML-M7. A more systematic search for chromosome 21 rearrangements in AML-M7 using FISH techniques is proposed.
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PMID:Acute megakaryocytic leukaemia with acquired polysomy 21 and translocation t(1;21). 1099 52

The AML1 gene, situated in 21q22, is often rearranged in acute leukemias through t(8;21) translocation, t(12;21) translocation, or less often t(3;21) translocation. Recently, point mutations in the Runt domain of the AML1 gene have also been reported in leukemia patients. Observations for mutations of the Runt domain of the AML1 gene in bone marrow cells were made in 300 patients, including 131 with acute myeloid leukemia (AML), 94 with myelodysplastic syndrome (MDS), 28 with blast crisis chronic myeloid leukemia (CML), 3 with atypical CML, 41 with acute lymphoblastic leukemia (ALL), and 3 with essential thrombocythemia (ET). Forty-one of the patients had chromosome 21 abnormalities, including t(8;21) in 6 of the patients with AML, t(12;21) in 8 patients with ALL, acquired trisomy 21 in 17 patients, tetrasomy 21 in 7 patients, and constitutional trisomy 21 (Down syndrome) in 3 patients. A point mutation was found in 14 cases (4.7%), including 9 (22%) of the 41 patients with AML of the Mo type (MoAML) (none of them had detectable chromosome 21 rearrangement) and 5 (38%) of the 13 myeloid malignancies with acquired trisomy 21 (1 M1AML, 2 M2AML, 1 ET, and 1 atypical CML). In at least 8 of 9 mutated cases of MoAML, both AML alleles were mutated: 3 patients had different stop codon mutations of the 2 AML1 alleles, and 5 patients had the same missense or stop codon mutation in both AML1 alleles, which resulted in at least 3 of the patients having duplication of the mutated allele and deletion of the normal residual allele, as shown by FISH analysis and by comparing microsatellite analyses of several chromosome 21 markers on diagnosis and remission samples. In the remaining mutated cases, with acquired trisomy 21, a missense mutation of AML1, which involved 2 of the 3 copies of the AML1 gene, was found. Four of the 7 mutated cases could be reanalyzed in complete remission, and no AML1 mutation was found, showing that mutations were acquired in the leukemic clone. In conclusion, these findings confirm the possibility of mutations of the Runt domain of the AML1 gene in leukemias, mainly in MoAML and in myeloid malignancies with acquired trisomy 21. AML1 mutations, in MoAML, involved both alleles and probably lead to nonfunctional AML1 protein. As AML1 protein regulates the expression of the myeloperoxidase gene, the relationship between AML1 mutations and Mo phenotype in AML will have to be further explored. (Blood. 2000;96:2862-2869)
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PMID:High incidence of biallelic point mutations in the Runt domain of the AML1/PEBP2 alpha B gene in Mo acute myeloid leukemia and in myeloid malignancies with acquired trisomy 21. 1102 23

In childhood acute lymphoblastic leukaemia (ALL) a number of genetic changes have been identified which provide diagnostic and prognostic information with a direct impact on patient management. The most significant abnormalities include the translocation, t(12;21)(p13;q22), giving rise to the ETV6/AML1 gene fusion; BCR/ABL arising from t(9;22)(q34;q11); re-arrangements of the MLL gene; the E2A/PBX1 from the t(1;19)(q23;p13); re-arrangements of MYC with the immunoglobulin genes and re-arrangements of the T cell receptor genes. Chromosomal deletions, particularly those of the short arms of chromosomes 9 and 12 and the long arm of chromosome 6, have been postulated to be the sites of tumour suppressor genes (TSG). Numerical chromosomal abnormalities are of particular importance in relation to prognosis. High hyperdiploidy (50-65 chromosomes) is associated with a good risk, whereas the outlook for patients with near haploidy (23-29 chromosomes) is extremely poor. In view of the introduction of risk-adjusted therapy into the UK childhood ALL treatment trials, an interphase FISH screening programme has been developed to reveal chromosomal abnormalities with prognostic significance in childhood ALL.
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PMID:The genetics of childhood acute lymphoblastic leukaemia. 1103 43

Hairy cell leukemia (HCL) is a chronic B-lymphocyte leukemia. Due to the proliferative inertia of the malignant cells, HCL-derived cell lines are an important tool for studies on this disease. We have elaborated the karyotypes of three HCL-derived cell lines, ESKOL, JOK-1, and Hair-M, by combining a range of molecular cytogenetic techniques, including multiplex (multicolor) fluorescence in situ hybridization (M-FISH), comparative genomic hybridization (CGH), conventional FISH, primed in situ labeling (PRINS), and dideoxyPRINS. We found ESKOL to be monoclonal with a single chromosome aberration, der(7)t(3;7)(q26.3;q31). JOK-1 also appeared to be monoclonal, having the karyotype 48,XY,der(4) t(1;4)(1pter-->p32::4qter-->pter), der(6)(6qter-->p22::q12--> qter), +der(7)t(7;11)(7pter-->q21::11p15-->pter),der(8)t(5;8;12) (5pter-->p14::12p11.2-->p12::8q12-->q21::8?cen-->-->24 .?2), der(14)t(8;14)(8qter-->q24.?2::14q32.3-->pter),+20. These karyotypes differ from the original descriptions of ESKOL and JOK-1. The Hair-M cells analyzed by us were found to be peritetraploid with numerous chromosomal rearrangements. The cell line was also found to be multiclonal. On this basis, we do not regard the Hair-M cell line to be suitable for HCL studies.
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PMID:Characterization of three hairy cell leukemia- derived cell lines (ESKOL, JOK-1, and hair-M) by multiplex-FISH, comparative genomic hybridization, FISH, PRINS, and dideoxyPRINS. 1106 Apr 41

The ETV6 gene is rearranged as a result of translocations involving a wide variety of chromosomal partners. To date, 12 partner genes for ETV6 have been cloned, and a further 23 chromosomal regions have been described. We previously identified a cryptic t(7;12) with ETV6 involvement in two cases of infant leukemia. The finding of a third case of t(7;12), also in an infant, prompted a more focussed search based on the common features found in these patients and those reported in the literature. The selection criteria were age at diagnosis < 20 months and the presence of +19 and/or +8 in the karyotype; cases with abnormalities of 7q and/or 12p were also considered. FISH studies using whole chromosome paints and probes for the ETV6 gene revealed a t(7;12) in 10 out of 23 cases studied. Seven of these had evidence of ETV6 rearrangement. Of those with ETV6 involvement, six had a 7q36 and one a 7q22 breakpoint. Importantly, in three cases the 7q36 breakpoint was within the same PAC, suggesting the existence of a new nonrandom translocation. However, in at least one patient the 7q36 breakpoint was different. The identification of the 7q partner genes will determine whether it is the disruption of ETV6 alone, or the formation of fusion genes, that is important for leukemogenesis in these patients. As both 7q36 and 7q22 are critical regions of gene loss in del(7q) leukemias, the identification of partner genes from these regions may also be important in understanding the pathogenesis of these diseases.
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PMID:t(7;12)(q36;p13), a new recurrent translocation involving ETV6 in infant leukemia. 1106 76

We report a case of childhood acute lymphoblastic leukemia with the simultaneous occurrence of a t(2;8)(p12;q24) typically associated with mature B cell or Burkitt leukemia, and a t(12;21)(p13;q22) exclusively associated with pre-B cell ALL. The lymphoblasts were characterized as L2 morphology by the French-American-British classification. However, there were atypical morphologic findings for L2 ALL, including vacuolization in some cells. The lymphoblasts were periodic acid-Schiff positive and myeloperoxidase negative. Immunophenotypic analysis revealed that the majority of lymphoblasts were TdT+, CD10+, CD19+, CD20-, and cytoplasmic mu+. These features were consistent with an immature pre-B cell leukemia phenotype with some characteristics of a mature B-cell leukemia. A t(2;8)(p12;q24)(p12;q24), characteristic of mature B-cell leukemia or Burkitt type leukemia, was detected by conventional cytogenetics with no other cytogenetic abnormalities. However, diagnostic peripheral blood and bone marrow specimens demonstrated simultaneous occurrence of a cryptic t(12;21)(p13;q22) by both FISH and RT-PCR. The simultaneous occurrence of these translocations in a pediatric patient have implications for the pathogenesis of leukemias with t(2;8)(p12;q24) as well as t(12;21)(p12;q22). Analysis of additional cases of leukemia with translocations involving the MYC locus on 8q24 will be required to determine the frequency of association with the cryptic t(12;21)(p13;22), and the prognostic significance of the simultaneous occurrence of the translocations.
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PMID:Translocation (2;8)(p12;q24) associated with a cryptic t(12;21)(p13;q22) TEL/AML1 gene rearrangement in a child with acute lymphoblastic leukemia. 1110 15

The information obtained by conventional cytogenetics (CC) in human leukemias is sometimes limited, in particular by complex karyotypes with many marker chromosomes. While CC is restricted to metaphases with a good quality, interphase fluorescence in situ hybridization (I-FISH) is also capable of analyzing specific anomalies in the interphase nuclei. Comparative genomic hybridization (CGH) gives additional information about the imbalanced karyotype changes in the whole genome. The aim of this study was to assess the contribution of CGH to the unraveling of complex GTG karyotypes, which are difficult to evaluate by banding analysis, and to compare these results with those by CC and FISH. Thirteen bone marrow samples and one sample obtained from peripheral blood of 13 leukemia patients were examined by CC, FISH and CGH. The GTG banding analysis showed complex karyotypes with many marker chromosomes. The most frequent abnormalities were numerical and structural aberrations on chromosomes 5 and 7. In 12 of the 14 samples, the CGH analysis was able to detect chromosomal imbalances with losses of material on chromosome 5 and 7 as the most frequent aberrations. In all 14 samples, additional FISH analyses were performed. For most of the studied neoplasias, a close correlation between CC, FISH and CGH data was observed. CGH was considerably helpful in adding additional information to classical karyotyping, if the low quality or number of metaphases was insufficient for a reliable CC analysis. Even in cases where whole chromosome painting could be applied, it added information on the breakpoints of the observed rearrangements. In only 2 of the studied 14 samples, neither CGH nor I-FISH could improve the result of karyotyping. CGH, nevertheless, can be regarded as a powerful additional technique in leukemias with unsuccessful CC, incomplete, or complex karyotypes with many marker chromosomes. A systematic analysis by three techniques such as CC, FISH and CGH guarantees an optimal genetic characterization of the neoplasias.
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PMID:Comparative genomic hybridization-aided unraveling of complex karyotypes in human hematopoietic neoplasias. 1116 14

One possible explanation for the competitive advantage that malignant cells in patients with acute myelogenous leukemia (AML) appear to have over normal hematopoietic elements is that leukemic progenitors proliferate more rapidly than their normal progenitor cell counterparts. To test this hypothesis, an overnight 3H-thymidine (3H-Tdr) suicide assay was used to analyze the proliferative status of malignant progenitors detected in both colony-forming cell (CFC) and long-term culture initiating cell (LTC-IC) assays from the peripheral blood of nine patients with newly diagnosed AML. Culture of AML cells in serum-free medium with 100 ng/ml Steel factor (SF), 20 ng/ml interleukin 3 (IL-3) and 20 ng/ml granulocyte colony-stimulating factor (G-CSF) for 16-24 h maintained the number of AML-CFC and LTC-IC at near input values (mean % input +/- s.d. for CFC and LTC-IC were 78 +/- 33 and 126 +/- 53, respectively). The addition of 20 muCi/ml high specific activity 3H-Tdr to these cultures reduced the numbers of both progenitor cell types from most of the patient samples substantially: mean % kill +/- s.d. for AML-CFC and LTC-IC were 64 +/- 27 and 82 +/- 16, respectively, indicating that a large proportion of both progenitor populations were actively cycling. FISH analysis of colonies from CFC and LTC-IC assays confirmed that most cytogenetically abnormal CFC and LTC-IC were actively cycling (mean % kill +/- s.d.: 68 +/- 26 and 85 +/- 13, respectively). Interestingly, in six patient samples where a significant number of cytogenetically normal LTC-ICs were detected, the % kill of these cells (74 +/- 20) was similar to that of the abnormal progenitors. These data contrast with the predominantly quiescent cell cycle status of CFC and LTC-IC previously observed in steady-state peripheral blood from normal individuals but also provide evidence that a significant proportion of primitive malignant progenitors from AML patients are quiescent and therefore may be resistant to standard chemotherapeutic regimens.
Leukemia 2000 Dec
PMID:Proliferative status of primitive hematopoietic progenitors from patients with acute myelogenous leukemia (AML). 1118 3

It has been proposed that adoptive immunotherapy, for the treatment of relapsed AML, with cytotoxic T lymphocytes which show a relative specificity for the leukemic cells may have the advantage of maximizing the beneficial anti-leukemic effect whilst minimizing the probability of graft-versus-host disease. In this study we differentiated peripheral blood AML cells in vitro into functional dendritic cells (DCs), as demonstrated by cell morphology, immunophenotype and functional activity, in the presence of GM-CSF, IL-4, TNF-alpha and FLT3 ligand. Such DCs could be differentiated from 77% of AML patients, irrespective of their FAB classification and clinical status and, in all cases tested, the DCs were shown to derive from the leukemic clone by FISH analysis. Importantly, from >60% of AML patients, autologous T lymphocytes stimulated with these in vitro generated leukemic DCs displayed specific cytotoxic activity against AML blasts but low reactivity against autologous non-leukemic targets and HLA-matched normal PBMNCs therefore suggesting that the CTLs were AML-specific. The use of FLT3 ligand in our system resulted in a significantly higher number of leukemic DCs as compared to cultures from which FLT3 ligand was omitted which is obviously advantageous if large numbers of specific CTLs are to be generated in the shortest possible time.
Leukemia 2001 Feb
PMID:Leukemic dendritic cells generated in the presence of FLT3 ligand have the capacity to stimulate an autologous leukemia-specific cytotoxic T cell response from patients with acute myeloid leukemia. 1123 40


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