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

A case of acute promyelocytic leukemia (APL) with cryptic PML-RAR alpha fusion on 17q and add(15p) as a secondary abnormality was characterized using molecular cytogenetic techniques. Spectral karyotyping (SKY) showed that chromosome 11 material was added to 15p, forming a der(15)t(11;15), which was refined to der(15)t(11;15)(q13.2;p13) with information obtained by comparative genomic hybridization (CGH). Interstitial insertion of chromosome 15 material into chromosome 17q was found by fluorescence in situ hybridization (FISH) with whole chromosome painting (WCP) probes. This study illustrates the necessity of a combination of molecular cytogenetics to decipher complex karyotypic abnormalities and cryptic translocations in leukemia.
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PMID:Molecular characterization of der(15)t(11;15) as a secondary cytogenetic abnormality in acute promyelocytic leukemia with cryptic PML-RAR alpha fusion on 17q. 1095 48

A 38-year-old male presented with fever and hepatosplenomegaly. Cells that had infiltrated to the bone marrow were consistent immunophenotypically and genotypically with natural killer (NK) cells. Oligoclonal Epstein-Barr virus infection was detected in the bone marrow cells. The patient was diagnosed as a case of aggressive NK cell leukemia/lymphoma. Combined chemotherapy was not effective and death occurred shortly after presentation. Although the karyotype of this case was too complicated to be accurately identified only by G-banding, spectral karyotyping (SKY) analysis not only identified all chromosomal materials of unknown origin, but also detected the cryptic translocation on the apparently normal chromosome. Moreover, SKY analysis identified der(4)t(4;14)(q12;q11.2). The chromosomal band 14q11.2 is a recurring breakpoint in T-cell non-Hodgkin's lymphoma, and is also the locus of the delta chain of the T-cell receptor. To our knowledge, t(4;14)(q12;q11.2) in T-cell or NK-cell malignancies has not been previously reported.
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PMID:Aggressive natural killer cell leukemia/lymphoma: a comprehensive cytogenetic study by spectral karyotyping. 1104 24

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

We used a recently described molecular cytogenetic method, spectral karyotyping (SKY), to analyze metaphase chromosomes from 30 pediatric patients with acute lymphoblastic leukemia (ALL). This group included 20 patients whose leukemic blast cells lacked chromosomal abnormalities detected by conventional cytogenetics and 10 patients whose blast cells had multiple chromosomal abnormalities that could not be completely identified by G-banding analysis. In two of the 20 patients (10%) with apparently normal karyotypes, SKY identified three cryptic translocations: a t(7;8)(q34-35;q24.1) in one patient and a t(13;17)(q22;q21) and a der(19)t(17;19)(q22;p13) in another. Fluorescence in situ hybridization using subtelomeric probes proved the latter translocation to be a t(17;19). SKY analysis was also successful in defining the nature of the chromosomal abnormalities in four of the 10 patients with marker and derivative chromosomes. The identified abnormalities in the latter group included three novel translocations: a der(X)t(X;5)(p11.4;q31), a der(21)t(X;21)(p11.4;p11.2) and a t(X;9)(p11.4;p13). The presence of the t(X;9) was suggested by conventional cytogenetics. The application of fluorescence in situ hybridization using chromosome-specific painting probes and locus-specific probes complemented the SKY analysis by confirming the nature of the chromosome rearrangements defined by SKY and by identifying the amplification of the AML1/CBFA2 gene in one patient with a duplicated 21q. Our study demonstrates the utility of SKY in identifying novel translocations and in refining the identity of chromosomal abnormalities in leukemias.
Leukemia 2001 Mar
PMID:Multicolor spectral karyotyping identifies novel translocations in childhood acute lymphoblastic leukemia. 1123 73

Three rearrangements in ALL disrupt E2A and create E2A fusion proteins: the t(1;19)(q23;p13) and E2A-PBX1, t(17;19)(q22;p13) and E2A-HLF and a cryptic inv(19)(p13;q13) and E2A-FB1. While E2A is fused to PBX1 in most ALLs with a t(1;19), 5-10% of cases have translocations that appear identical, but do not affect E2A or PBX1. Because more intensive therapy improves the outcome of patients with E2A-PBX1positive (1;19) translocations, it is critical to identify this subset of patients so that appropriate therapy can be administered. In addition, there are balanced and unbalanced variants of the t(1;19) and controversy exists regarding the clinical significance of this distinction. We have developed a two-color fluorescence in situ hybridization assay that accurately detects E2A translocations in metaphase and interphase cells, distinguishes between balanced and unbalanced variants and identifies patients with a t(1;19) who lack E2A-PBX1 fusion. We found that clonal microheterogeneity is common in patients with E2A translocations and most patients have mixtures of cells with balanced and unbalanced translocations, suggesting that this distinction represents two ends of a continuum rather than distinct biological entities. These reagents should have widespread clinical utility and be useful for translational and basic research studies involving E2A translocations and this region of chromosome 19p13.
Leukemia 2001 Jan
PMID:Detection of E2A translocations in leukemias via fluorescence in situ hybridization. 1124 6

The t(4;11) translocation is the cytogenetic hallmark of a subset of acute lymphoblastic leukemias characterized by pro-B immunophenotype and a dismal prognosis. This translocation fuses the MLL gene on chromosome band 11q23 and the AF4 gene on 4q21, resulting in the expression of fusion transcripts from both translocated chromosomes. The MLL-AF4 chimeric transcript is thought to mediate the leukemic transformation. The MLL genomic disruption detected by Southern blot and the RT-PCR for the MLL-AF4 chimeric transcript expression are molecular evidence of this chromosomal translocation. However, similar molecular rearrangements have also been identified in cases without the cytogenetic t(4;11). We report a 30-year-old patient with high risk ALL, a normal karyotype, and molecular evidence of MLL-AF4 fusion. Using a double color FISH assay with MLL specific PAC probes, a cryptic t(4;11) due to insertion of 5' MLL sequences in chromosome 4q21 was demonstrated. Consequently the MLL-AF4 was encoded by der(4). This insertion mechanism precludes the genomic recombination of AF4-MLL and supports the crucial role played by MLL-AF4 in leukemogenesis. The findings of our case, along with others, show the importance of complementing the karyotype with molecular and FISH techniques.
Leukemia 2001 Apr
PMID:Cryptic t(4;11) encoding MLL-AF4 due to insertion of 5' MLL sequences in chromosome 4. 1136 62

The TEL-AML1 fusion which results from a cryptic t(12;21) translocation is the most frequently occurring genetic abnormality in childhood acute lymphoblastic leukemia (ALL) and has been associated with an excellent treatment outcome. In the present study, we examined the FAS/BCL-2 expression profiles and chemosensitivity of primary leukemic cells from children with newly diagnosed t(12;21)TEL-AML1 fusion transcript-positive versus t(12;21)TEL-AML1 fusion transcript-negative standard risk ALL. TEL-AML1(+) ALL cells expressed higher levels of the pro-apoptotic protein Fas and lower levels of the anti-apoptotic protein Bcl2 than TEL-AML1(-) ALL cells, as determined by confocal laser scanning microscopy. TEL-AML1(+) ALL cells were more sensitive to the apoptosis-inducing effects of serum deprivation, dexamethasone and vincristine than TEL-AML1(-) ALL cells. This study provides novel mechanistic insights regarding the chemosensitivity of TEL-AML1(+) ALL cells and provides a cogent explanation for the excellent leukemia-free survival outcome of children with TEL-AML1(+) ALL treated on contemporary chemotherapy programs.
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PMID:Chemosensitivity of TEL-AML1 fusion transcript positive acute lymphoblastic leukemia cells. 1137 79

Chromosomal analysis plays an important role in the diagnosis, treatment and prognosis of human leukemia. Currently, the GTG-banding technique (G-banding) is the most commonly used diagnostic method in clinical cytogenetics. G-banding analysis of subtle chromosomal rearrangements or complex karyotypes with multiple markers can be inadequate because of poor chromosome morphology and/or an insufficient yield of analyzable metaphases. Fluorescence in situ hybridization (FISH) is a highly sensitive and specific method to detect chromosomal alterations. Conventional FISH is used optimally in instances where only one or a few abnormalities are investigated. Spectral karyotyping (SKY), a novel cytogenetic technique, has been developed to unambiguously display and identify all chromosomes at one time using a spectrum of 24 different colors. This report presents the use of SKY for examination of the entire karyotype in specimens with complex chromosomal abnormalities from three leukemia patients. Conventional cytogenetic analysis (G-banding) showed complex hyperdiploid clones with multiple markers in each case. SKY was able to clarify and identify additional cryptic chromosomal translocations [e.g., t(2;10), t(3;10), t(5;7), t(7;18), t(9;17), t(10;12), t(13;16)] insertions [e.g., ins(17;9), ins(20;Y)], duplications [e.g., i(8)(q10), dup(4)(q31q35)] and marker chromosomes in each case. This study demonstrates that the combination of SKY and G-band techniques results in a more complete characterization of the complex chromosomal aberrations seen in leukemia.
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PMID:Spectral karyotyping study of chromosome abnormalities in human leukemia. 1142 54

Lymphoblasts from children with B-progenitor cell acute lymphoblastic leukemia (BpALL) with chromosomal hyperdiploidy and with translocations affecting chromosome 12p11-13, accumulate high and low levels of methotrexate polyglutamates (MTXPGs), respectively. Recently a cryptic translocation, t(12;21) (p13;q22), has been demonstrated by molecular and fluorescence in situ hybridization techniques in this disease. The chimeric TEL-AML1 transcript, which has been associated with this translocation, can be detected in up to 25% of children with BpALL. We detected the TEL-AML1 and/or the AML1-TEL transcript in 30 (33%) of 91 patients studied. Levels of lymphoblast MTXPGs were lower in those with than in those without the TEL-AML1 translocation (P = 0.004). Hyperdiploidy was rare in lymphoblasts with the TEL-AML1 translocation (P = 0.047). Both ploidy (P= 0.0015) and TEL-AML1 status (P= 0.0043) were independently and significantly correlated with the log of the lymphoblast MTXPG level. However, the presence of TEL-AML1 or of hyperdiploidy accounted for only 22% of the variation of this value. Our results imply that each of 1.16 > or = DI and the presence of the TEL-AML1 translocation confers a 50% decrease in lymphoblast MTXPG level. When planning reduction of therapy for either of the two excellent outcome categories of hyperdiploid or TEL-AML1 BpALL, one should consider the difference between these two subgroups in the ability of lymphoblasts to accumulate MTXPGs.
Leukemia 2001 Jul
PMID:The association of the TEL-AML1 chromosomal translocation with the accumulation of methotrexate polyglutamates in lymphoblasts and with ploidy in childhood B-progenitor cell acute lymphoblastic leukemia: a Pediatric Oncology Group study. 1145 77


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