Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0023418 (leukemia)
 93,477 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The splice donor and acceptor sequences for the subgenomic envelope messenger RNA of feline leukemia virus (FeLV) were determined. The splice junction was characterized for viral mRNA from a prototype subgroup A FelV and an immunodeficiency-inducing FeLV variant. Thirty-seven of 38 partial envelope cDNAs, cloned after PCR amplification from T cells infected with either virus, utilized the same splice donor and acceptor sites to generate a mRNA that would be predicted to encode envelope protein. One novel cDNA, which could also code for envelope protein, was generated from a cryptic splice acceptor 109 nucleotides downstream of the normal junction. No additional subgenomic FeLV gene products were detected using reverse transcription and polymerase chain reaction amplification of FeLV sequences from chronically infected cells.
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PMID:Nucleotide sequence of the splice junction of feline leukemia virus envelope mRNA. 839 48

We have analysed DNA and RNA from 36 T-cell lymphomas induced in Fischer rats by Moloney murine leukemia virus for alterations affecting the structure or expression of the lck gene. At least five primary tumors (14%) have a proviral insertion upstream of lck. In at least four of the tumors, proviral insertion increases lck mRNA levels an average of eight-fold. Overexpression of lck results from transcription initiating in the viral promoter and extending into lck sequences. Three different structures of hybrid transcript were detected. In all three, the hybrid RNAs are spliced to a normal lck splice acceptor in the first exon of lck, resulting in removal of three out of frame ATG codons which would be expected to increase the translation efficiency of the hybrid message. In one tumor, the viral splice donor is used, in one tumor, proviral insertion generates a splice donor sequence one base pair downstream of the long terminal repeat boundary, and in two tumors, a cryptic splice donor in the upstream lck sequences is used. The significance of these unusual splicing patterns and of the higher frequency of proviral insertions adjacent to lck in rats relative to mice is discussed.
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PMID:Frequent activation of the lck gene by promoter insertion and aberrant splicing in murine leukemia virus-induced rat lymphomas. 842 92

Tissue factor (TF) exists in a cryptic form [i.e. without procoagulant activity (PCA)] in peripheral blood monocytes and quiescent tissue macrophages but is expressed constitutively in most human tumor cells. Induction and cell surface expression of TF in these cells in vivo is associated with activation of intravascular and extravascular coagulation in patients with a variety of inflammatory or malignant diseases. The regulation of TF synthesis in cells is complex and new information from transfection studies suggests that changes in cellular glycosylation pathways impair cell surface expression of functional TF. Such dysregulation may also characterize the lineage-unfaithful expression of TF in leukemic cells and perhaps explain some of the thrombohemorrhagic complications in patients with acute progranulocytic leukemia. The importance of carbohydrate modification of TF is reviewed.
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PMID:Tissue factor expression in human leukocytes and tumor cells. 857 92

The t(12;21)(p13;q22) is identified by routine cytogenetics in less than 0.05% of pediatric acute lymphoblastic leukemia (ALL) patients. This translocation encodes a TEL/AML-1 chimeric product comprising the helix-loop-helix domain of TEL, a member of the ETS-like family of transcription factors, fused to AML-1, the DNA-binding subunit of the AML-1/CBF beta transcription factor complex. Both TEL and AML-1 are involved in several myeloid leukemia-associated translocations with AML-1/CBF beta being altered in 20-30% of de novo acute myeloid leukemia (AML) cases. We now demonstrate that a TEL/AML1 chimeric transcript encoded by a cryptic t(12;21) is observed in 22% of pediatric ALL, making it the most common genetic lesion in these patients. Moreover, TEL/AML1 expression defined a distinct subgroup of patients characterized by an age between 1 and 10 years, B lineage immunophenotype, non-hyperdiploid DNA content and an excellent prognosis. These data demonstrate that molecular diagnostic approaches are invaluable in identifying clinically distinct subgroups, and that the AML1/CBF beta transcription complex is the most frequent target of chromosomal rearrangements in human leukemia.
Leukemia 1995 Dec
PMID:TEL/AML1 fusion resulting from a cryptic t(12;21) is the most common genetic lesion in pediatric ALL and defines a subgroup of patients with an excellent prognosis. 860 6

Monosomy 7 (-7) and deletion of the long arm of chromosome 7, del(7q), are frequent non-random findings in the myelodysplastic syndromes (MDS) and acute myeloid leukaemia (AML), particularly associated with therapy-related disease (t-MDS and t-AML). The cytogenetic breakpoints of 7q deletions are variable, with both terminal and interstitial deletions reported. It is now believed that most deletions are interstitial, and that the variability in reported breakpoints may be due to the difficulty in determining whether the terminal, pale staining G band is present. It has also been suggested that some reported deletions of 7q may be cryptic translocations. To address these questions, we carried out fluorescence in situ hybridization (FISH) studies on leukaemic cells from a large series of patients using a chromosome 7-specific paint and a 7q telomere-specific probe. Of the 26 cases studied, seven were 'pure' deletions (ie without the involvement of other chromosomes); four were interstitial and two terminal. One further patient had two clones each with a different deletion: one with a terminal del(7)(q22) and the second with an interstitial del(7)(q32-qter). A further nine cases had unbalanced translocations with deletion of 7q terminal sequences. The remaining 10 cases were translocations and complex rearrangements, some involving interstitial deletions of 7q. In two cases in which del(7q) was reported as the sole cytogenetic abnormality by G-banding, FISH revealed cryptic translocations involving 7q.
Leukemia 1996 Apr
PMID:Classification of deletions and identification of cryptic translocations involving 7q by fluorescence in situ hybridization (FISH). 861 41

Moloney murine leukemia virus (MLV) having the gag coding region alone, G3.6, produced a low level of mRNA (1/10 of the wild-type level). Ligation of 441 nucleotides (nt) containing a splice acceptor (SA) site to the downstream portion of the remaining gag region restored the level of the unspliced message, simultaneously activating a cryptic splice donor (SD) site in the middle of the p30 coding region (between nt 1596 and 1597). Ligation of the 441 nt in the same site in the inverted orientation also increased the level of the unspliced message, activating the same SD site (between nt 1596 and 1597) and a new SA site just in front of the inserted 441 nt (between nt 4770 and 4771). Deletion or inversion of the 441-nt SA sequence from the wild-type MLV or from int in-frame deletion or int frameshift mutant MLVs of nearly full size resulted in the loss of spliced mRNA and concomitantly in a severe reduction of the unspliced mRNA, particularly at 37 degrees C. Deletion of the 5' SD site did not result in the reduction of the unspliced-mRNA level. When the gag region in G3.6 was replaced with a Neo(r) coding region, the level of expression was high. The data taken together suggest that the presence of an SA signal is necessary for high-level expression of unspliced mRNA encoding Gag or Gag-Pol.
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PMID:Possible role of splice acceptor site in expression of unspliced gag-containing message of Moloney murine leukemia virus. 864 55

Recently, a new recurrent t(12;21)(pl3;q22) has been identified in a B-cell lineage childhood acute lymphoblastic leukemia (ALL). The translocation results in a fusion of two known genes, ETV6/TEL (12p13) and AML1 (21q22), previously shown to be involved in the pathogenesis of myeloid disorders. We report results of cytogenetic fluorescence in situ hybridization and molecular studies of a B-cell childhood common ALL with a cryptic 12;21 translocation. Aberrations identified in this case involve both chromosomes 12 and include not only the ETV6-AML1 gene fusion and two different microdeletions of ETV6 but also the hemizygous loss of CDKN1B, D12S119, and KRAS2 loci and a putative rearrangement of the second CDKN1B allele as a result of an inv(12)(p13q24). Moreover, it was shown that the AML1-ETV6 reciprocal chimeric transcript was not present in the malignant cells, and hence may not play a major role in leukemogenesis. In addition, the putative loss of wild-type function of CDKN1B and ETV6 could indicate a synergistic effect of both genes in the pathogenesis of this leukemia case.
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PMID:Biallelic alterations of both ETV6 and CDKN1B genes in a t(12;21) childhood acute lymphoblastic leukemia case. 865 12

Despite its rarity by routine karyotypic analysis, cryptic t(12;21)(p12-13;q22) translocation leading to TEL/AML1 fusion has been recognized as the most frequent genetic rearrangement in childhood acute lymphoblastic leukemia (ALL) in two recent studies, one from France and the other from the United States. To estimate the frequency of this abnormality in the Chinese population, we studied 41 children with ALL and 17 with acute myeloid leukemia (AML) in two medical centers in Taiwan, using the reverse transcriptase polymerase chain reaction (RT-PCR) assay. Results of this analysis demonstrated a 17% frequency of this translocation in the ALL population overall and 19% in patients with B-lineage ALL, similar to previous findings in Caucasian children. None of the patients with AML had TEL/AML1 fusion transcripts. In addition to its association with the B-lineage immunophenotype, TEL/AML1 was also correlated with a low presenting leukocyte count and favorable age (1-10 years). These findings, combined with earlier reports, indicate that TEL/AML1 fusion is the most frequent genetic abnormality in childhood ALL, regardless of race. Molecular diagnosis of t(12;21)-positive ALL may identify a subgroup of patients who do not require intensive treatment for cure.
Leukemia 1996 Jun
PMID:High incidence of TEL/AML1 fusion resulting from a cryptic t(12;21) in childhood B-lineage acute lymphoblastic leukemia in Taiwan. 866 57

Detection of the t(15;17) or its molecular consequence, the PML-RAR alpha rearrangement, is critical for meaningful analysis of clinical trials involving patients with suspected acute promyelocytic leukaemia (APL). Its presence remains the best predictor of a favourable response to retinoids, such as ATRA, which in combination with chemotherapy confer significant improvements in disease-free survival. We have evaluated the relative efficacy of RT-PCR, cytogenetics and PML immunofluorescence staining to identify the existence of the translocation in 100 patients entered into the Medical Research Council (M.R.C.) ATRA trial. RT-PCR successfully identified PML-RAR alpha rearrangements in 93/100 patients, including 65 where only peripheral blood or post-induction marrow samples were available for analysis and in 12 patients in whom cytogenetic assessment failed to demonstrate t(15;17) due to poor-quality metaphases (10/12) or as a reflection of cryptic PML-RAR alpha rearrangements (2/12). Parallel employment of the RAR alpha-PML assay confirmed expression of del(17q)-derived transcripts in 81% and permitted determination of the PML breakpoint (a potential independent prognostic variable) in all 93 cases. Sequencing of RT-PCR products derived from 50 patients with 3' PML breakpoints revealed five bcr 2 cases, including a novel exon 5 breakpoint. 35/81 (43%) patients with cytogenetic evidence of t(15;17) possessed additional karyotypic abnormalities. In four patients with available buffy coat smears, lack of cytogenetic or molecular evidence of the t(15;17) was confirmed by a wild-type PML immunofluorescence nuclear staining pattern, in contrast to the characteristic microparticulate distribution detected in 14 patients with RT-PCR evidence of the rearrangement. However, although PML immunofluorescence staining is suitable for rapid determination of patients likely to benefit from ATRA, this approach does not obviate the need for cytogenetic and RT-PCR analysis of all patients entered into APL clinical trials, because both techniques provide additional information which may prove to be of independent prognostic significance.
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PMID:Establishing the presence of the t(15;17) in suspected acute promyelocytic leukaemia: cytogenetic, molecular and PML immunofluorescence assessment of patients entered into the M.R.C. ATRA trial. M.R.C. Adult Leukaemia Working Party. 879 Jan 59

Restriction endonuclease (RE) in situ digestion (REISD) of human metaphase chromosomes and interphase nuclei may uncover cryptic polymorphisms. This technique can be applied to identify the individual origin of cells and thus analyze the hemopoietic chimerism that eventually results in leukemic patients after allogeneic bone marrow transplantation (BMT). In the current study, results of REISD with different REs are shown. In particular, the use of Sau 3A reveals a polymorphism for constitutive heterochromatin of chromosome 3 and may differentiate BMT donor (D) and recipient (R) cells. Once pre-BMT characterization shows a different Sau 3A digestion pattern of D and R cells, it is possible to monitor the development of hematopoietic cell populations in the R bone marrow after BMT. A panel of 24 patients who underwent BMT and their Ds were analyzed. The method presented here allowed cells from D and R to be distinguished, and therefore to quantify the post-BMT hemopoletic chimerism, in 6 (25%) of the cases. This quantitative and sex-independent genetic approach to the study of hemopoietic chimerism has already shown itself to be useful in patients with leukemia who require a BMT, but could also be extended to other transplant situations.
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PMID:Restriction endonuclease in situ digestion (REISD): a novel quantitative sex-independent method to analyze chimerism after bone marrow transplantation. 886 45


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