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Query: UMLS:C0026986 (myelodysplastic syndrome)
 14,926 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Chromosomal rearrangements of the MLL gene are uncommon in myelodysplastic syndromes (MDSs), and few studies of their molecular structures and oncogenic mechanisms exist. Here, we present a case of de novo MDS with a normal karyotype at initial diagnosis and a mild clinical course. Five years after the initial diagnosis, investigators identified a complex rearrangement of the MLL gene without progression to acute leukemia. The 5' part of the MLL gene is fused out of frame with the LOC100131626 gene, and the 3' part of the MLL gene out of frame with the TCF12 gene. Rapid amplification of complementary DNA 3' ends yielded two main fusion transcripts, which is in concordance with the two described isoforms of the LOC100131626 gene. For both isoform-fusion transcripts, the open reading frame terminates shortly after the breakpoint that is predicted to form two de facto truncated MLL proteins and disrupts the open reading frame of the LOC100131626, TCF12, and UBE4A genes. Neither dimerization nor a transcriptional activation domain, each of which is causally linked to MLL protein-mediated transformation, is present. This and other unusual MLL rearrangements probably represent a subclass of MLL gene abnormalities that have intrinsically no ability or only a weak ability to transform hematopoeitic cells and are identified only in the context of other hematopoetic malignancies.
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PMID:A complex MLL rearrangement identified five years after initial MDS diagnosis results in out-of-frame fusions without progression to acute leukemia. 2213 86

One mechanism for disrupting the MLL gene in myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML) is through partial tandem duplication (MLL-PTD); however, the mechanism by which MLL-PTD contributes to MDS and AML development and maintenance is currently unknown. Herein, we investigated hematopoietic stem/progenitor cell (HSPC) phenotypes of Mll-PTD knock-in mice. Although HSPCs (Lin(-)Sca1(+)Kit(+) (LSK)/SLAM(+) and LSK) in Mll(PTD/WT) mice are reduced in absolute number in steady state because of increased apoptosis, they have a proliferative advantage in colony replating assays, CFU-spleen assays, and competitive transplantation assays over wild-type HSPCs. The Mll(PTD/WT)-derived phenotypic short-term (ST)-HSCs/multipotent progenitors and granulocyte/macrophage progenitors have self-renewal capability, rescuing hematopoiesis by giving rise to long-term repopulating cells in recipient mice with an unexpected myeloid differentiation blockade and lymphoid-lineage bias. However, Mll(PTD/WT) HSPCs never develop leukemia in primary or recipient mice, suggesting that additional genetic and/or epigenetic defects are necessary for full leukemogenic transformation. Thus, the Mll-PTD aberrantly alters HSPCs, enhances self-renewal, causes lineage bias, and blocks myeloid differentiation. These findings provide a framework by which we can ascertain the underlying pathogenic role of MLL-PTD in the clonal evolution of human leukemia, which should facilitate improved therapies and patient outcomes.
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PMID:Stress hematopoiesis reveals abnormal control of self-renewal, lineage bias, and myeloid differentiation in Mll partial tandem duplication (Mll-PTD) hematopoietic stem/progenitor cells. 2274 Apr 49

This study was aimed to investigate the clinical value of multiplex nested reverse transcription PCR (RT-PCR) in detecting MLL-related fusion genes in myelodysplastic syndrome (MDS). Ten MLL-related genes (dupMLL, MLL-ELL, MLL-ENL, MLL-AF6, MLL-AF9, MLL-AF10, MLL-AF17, MLL-CBP, MLL-AF1P, MLL-AF1Q) in 221 MDS cases were detected by multiplex nested RT-PCR. The results indicated that 20 patients were detected with positive result among 221 patients and the positive rate was 9.05%. The number of the positive cases and positive rates of the above mentioned 10 fusion genes were in order: 7 (3.16%), 2 (0.9%), 1 (0.45%), 1 (0.45%), 2 (0.9%), 2 (0.9%), 1 (0.45%), 2 (0.9%), 1 (0.45%), 1 (10.45%). It is concluded that the multiplex nested RT-PCR has been confirmed to be able to detect 10 fusion genes in MDS patients, which can provide important evidences for assessing diagnosis and treatment, and give related necessary information about minimal residual disease and its prognosis.
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PMID:[Application of multiplex nested RT-PCR to detecting 10 fusion genes related with MLL gene in myelodysplastic syndrome]. 2293 58

Improvements in chemotherapy and medical support of patients treated with chemotherapy and radiation have led to an ever-increasing number of cancer survivors. Unfortunately, a small fraction of these patients develop secondary hematologic malignancies as a consequence of their exposure to genotoxic anti-cancer regimens. Most of these are myeloid malignancies, therapy-related acute myeloid leukemia (t-AML) or myelodysplasia (t-MDS); however, a small but growing body of literature exists, which describes therapy-related acute lymphoblastic leukemias (t-ALL). Nearly all these cases are reportedly associated with translocations involving chromosome 11q23, the site of the MLL gene. We herein report two cases of ALL occurring after chemotherapy for other malignancies that showed complex karyotypic abnormalities and distinct MLL amplification by fluorescence in situ hybridization analysis. Immunophenotypic analysis showed that both cases expressed a pro-B cell (CD10-) phenotype with aberrant myeloid antigen expression. Although MLL amplification has been reported in therapy-related myeloid disease, to our knowledge this is the first report of MLL amplification occurring in therapy-related B cell ALL.
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PMID:Therapy-related pro-B cell acute lymphoblastic leukemia: report of two patients with MLL amplification. 2323 85

RUNX1 is generally considered a tumor suppressor in myeloid neoplasms. Inactivating RUNX1 mutations have frequently been found in patients with myelodysplastic syndrome (MDS) and cytogenetically normal acute myeloid leukemia (AML). However, no somatic RUNX1 alteration was found in AMLs with leukemogenic fusion proteins, such as core-binding factor (CBF) leukemia and MLL fusion leukemia, raising the possibility that RUNX1 could actually promote the growth of these leukemia cells. Using normal human cord blood cells and those expressing leukemogenic fusion proteins, we discovered a dual role of RUNX1 in myeloid leukemogenesis. RUNX1 overexpression inhibited the growth of normal cord blood cells by inducing myeloid differentiation, whereas a certain level of RUNX1 activity was required for the growth of AML1-ETO and MLL-AF9 cells. Using a mouse genetic model, we also showed that the combined loss of Runx1/Cbfb inhibited leukemia development induced by MLL-AF9. RUNX2 could compensate for the loss of RUNX1. The survival effect of RUNX1 was mediated by BCL2 in MLL fusion leukemia. Our study unveiled an unexpected prosurvival role for RUNX1 in myeloid leukemogenesis. Inhibiting RUNX1 activity rather than enhancing it could be a promising therapeutic strategy for AMLs with leukemogenic fusion proteins.
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PMID:Transcription factor RUNX1 promotes survival of acute myeloid leukemia cells. 2397 64

Gene amplification (amp) is one of the basic mechanisms connected with overexpression of oncogenes. The c-MYC (located in 8q24) and MLL (located in 11q23) are the most often over represented genes that lead to a rapid proliferation of the affected cell clone in patients with myeloid neoplasms. Assessment of the level of amp c-MYC or amp MLL in the cases with trisomy 8 (+8) or trisomy 11 (+11) and myeloid malignances is necessary for a more precise estimation of the disease progression. A total of 26 patients with acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS) were included in the study: 18 with +8, six with +11 and two with complex karyotypes suspected of the partial trisomy. Routine cytogenetic analysis and fluorescent in situ hybridization (FISH) were applied to indicate the chromosome alterations and genes amp in the bone marrow cells. Amp c-MYC was observed in 12 from 18 (66.7%) patients with +8. All the patients with +11 demonstrated a different level of amp MLL. In most of the cases with MDS (9/10), the coincidence of the +8 or +11 with amp c-MYC or amp MLL, respectively, leads to transformation to AML and/or short overall survival. Our data suggest that amp c-MYC and amp MLL develop in conformity with +8 and +11, especially in cases with progressive deviations in the karyotype as an aggressive expansion of an aberrant cell clone and appearance of additional chromosome anomalies.
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PMID:Amplification of c-MYC and MLL Genes as a Marker of Clonal Cell Progression in Patients with Myeloid Malignancy and Trisomy of Chromosomes 8 or 11. 2405 8

The aim of this study was to investigate the clinical characteristics and prognosis of acute erythroleukemia (AEL, AML-M6). The clinical features and results of morphologic, immunophenotypic, cytogenetic and molecular biologic detections were retrospectively analyzed in 13 cases of AEL from 305 acute leukemia patients hospitalized between October 2007 and October 2012. The results showed that the expression of erythroid and non-erythroid cells increased at the same time. The myeloid antigens mainly expressed CD13/CD33/CD117/CD34, while the erythroid antigens expressed Gly and CD71. The karyotypic detection indicated that there were 1 case with normal karyotype, 3 cases with simple karyotypic abnormality and 2 cases with complex karyotypic abnormality, the other cases were not detected. The molecular biological detection found that the poor prognosis gene existed in 5 cases [38.5% (5/13)], including 3 cases with MLL-MLL fusion gene, 1 case with MLL mutation, and 1 cases with NRAS gene mutation, the abnormal genes were not detected in remainder 8 cases. After chemotherapy with decitabine, the complete remission (CR) rate achieved 53.5% (7/13), partial remission (DR) rate achieved 15.4% (2/13). Finally, 8 patients received allo-HSCT, the median overall survival (OS) was 20.7 months, 3 year survival rate was 79%, 3 year disease-free survival rate was 78%. It is concluded that the acute erythroleukemia is a rare subtype of AML, which is transformed from MDS and has harmful genes and poor prognosis. Allo-HSCT and treatment with decitabine may enhance the survival rate of AEL.
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PMID:[Analysis of clinical characteristics and prognosis of 13 cases of acute erythroleukemia]. 2415 22

Rearrangements of the MLL gene located at chromosome 11q23 are common chromosomal abnormalities associated with acute leukemias. In vast majority of cases with MLL gene rearrangements, only one chromosome 11 or a single MLL allele got involved. We report two very unusual cases of myeloid neoplasms with homozygous inv(11)(q21q23) and biallelic MLL rearrangement. Both patients, a 12-year old boy and a 29-year old woman, presented initially with T lymphoblastic leukemia/lymphoma (T-ALL), achieved complete remission with intensive chemotherapy, then recurred as acute myeloid leukemia in one patient and therapy-related myelodysplastic syndromes in the other patient, 24 and 15 months after initial T-ALL diagnosis, respectively. In both cases, biallelic MLL gene rearrangements were confirmed by fluorescence in situ hybridization. Mastermind like 2 gene was identified as MLL partner gene in one case. To our knowledge, homozygous inv(11)(q21q23) with two MLL genes rearrangement are extremely rare; it is likely a result of acquired uniparental disomy.
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PMID:Homozygous inv(11)(q21q23) and MLL gene rearrangement in two patients with myeloid neoplasms. 2503 40

MLL gene rearrangements are well-recognized aberrations in acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS). In contrast, MLL gene amplification in AML/MDS remains poorly characterized. Here, we report a series of 21 patients with myeloid neoplasms associated with MLL gene amplification from 1 institution. This series included 13 men and 8 women, with a median age of 64 years. Eleven patients presented as AML with myelodysplasia-related changes, 6 as therapy-related AML, and 4 as therapy-related MDS. All patients had a highly complex karyotype, including frequent -5/del(5q), -18, and -17/del(17p) abnormalities; 16 patients were hypodiploid. TP53 mutations were detected in all 12 patients tested, and 3 patients showed TP53 mutation before MLL amplification. Morphologically, the leukemic cells frequently showed cytoplasmic vacuoles, bilobed nuclei, and were associated with background dyspoiesis. Immunophenotypically, 15 patients had a myeloid and 4 had myelomonocytic immunophenotype. Laboratory coagulopathies were common; 7 patients developed disseminated intravascular coagulopathy, and 3 died of intracranial bleeding. All patients were refractory to therapy; the median overall survival was 1 month, after MLL gene amplification was detected. We concluded that AML/MDS with MLL gene amplification is likely a subset of therapy-related AML/MDS or AML with myelodysplasia-related changes, associated with distinct clinicopathological features, frequent disseminated intravascular coagulopathy, a highly complex karyotype, TP53 deletion/mutation, and an aggressive clinical course.
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PMID:MLL gene amplification in acute myeloid leukemia and myelodysplastic syndromes is associated with characteristic clinicopathological findings and TP53 gene mutation. 2538 13

The aim of our study was 1) to define if the amplification of c-MYC, MLL and RUNX1 genes is related to the progressive changes of the karyotype in patients with AML and MDS with trisomy 8, 11 and 21 (+8, +11 and +21) in bone marrow and 2) can that amplification be accepted as part of the clonal evolution (CE). Karyotype analysis was performed in 179 patients with AML or MDS with the different chromosomal aberrations (CA) aged 16-81. The findings were distributed as follow: initiating balanced CA (n = 60), aneuploidia (n = 55), unbalanced CA (n = 64). Amplification of c-MYC, MLL and RUNX1 genes by means of fluorescence in situ hybridization (FISH) was found in 35% (7 out of 20) of AML and MDS patients with +8, +11 u +21 as single CA in their karyotype; in 63.6% of pts (7 out of 11)--with additional numerical or structural CA and in 75% (9 out of 12)--with complex karyotype. We assume that the amplification of the respective chromosomal regions in patients with +8, +11 and +21 is related to CE. Considering the amplification as a factor of CE, we established 3 patterns of karyotype development depending on the type of the initiating CA in it. Significant statistical differences were found between the three patterns regarding the karyotype distribution in the different stages of progression (p < 0.001).
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PMID:IS THE AMPLIFICATION OF c-MYC, MLL AND RUNX1 GENES IN AML AND MDS PATIENTS WITH TRISOMY 8, 11 AND 21 A FACTOR FOR A CLONAL EVOLUTION IN THEIR KARYOTYPE? 2621 2


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