Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0026986 (myelodysplastic syndrome)
 14,926 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Mutations in the genes of hematopoietic growth factor receptors as a cause of congenital cytopenia, such as congenital amegakaryocytic thrombocytopenia (CAMT) or severe congenital neutropenia (CN), are discussed. There are striking differences in the relevance of receptor mutations in these diseases. CAMT is a rare disease characterized by severe hypomegakaryocytic thrombocytopenia during the first years of life that develops into pancytopenia in later childhood. In patients with CAMT, we found inherited mutations in c-mpl, the gene coding for the thrombopoietin receptor, in 8 out of 8 cases. The type of mutation seems to correlate with the clinical course seen in the patients. Functional studies demonstrated defective thrombopoietin (TPO) reactivity in hematopoietic progenitor cells and platelets in CAMT patients. CN is a group of hematopoietic disorders characterized by profound, absolute neutropenia due to a maturation arrest of myeloid progenitor cells. About 10% of all patients develop secondary MDS/leukemia. The malignant progression is associated with acquired nonsense mutations within the G-CSF receptor gene that lead to the truncation of the carboxy-terminal cytoplasmic domain of the receptor protein involved in maturation of myeloid progenitor cells. This seems to be one important step in leukemogenesis in CN patients. CAMT is caused by inherited mutations in c-mpl, the gene for the thrombopoietin receptor, which lead to reduced or absent reactivity to TPO. In contrast, mutations in the G-CSF receptor in CN are acquired and are most probably connected with progression of the neutropenia into MDS/leukemia as a result of a loss of differentiation signaling.
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PMID:Implications of mutations in hematopoietic growth factor receptor genes in congenital cytopenias. 1145 19

Hematopoietic colony-stimulating factors have been introduced into clinical practice as additional supportive measures to reduce infectious complications associated with congenital or acquired neutropenia. Over the past decade, we have begun to appreciate the subtler aspects of the proper use of G-CSF and GM-CSF, identifying appropriate indications and contraindications. In the course of evaluating the corpus of studies, a set of formal recommendations have been propagated for the judicious use of these expensive growth factors. To prevent serious infection, the use of G-CSF or GM-CSF is recommended in a subset of pediatric cancer patients shortly after having received chemotherapy or a form of a marrow transplant. Children with highly intensive chemotherapy (e.g., children with high risk ALL or NHL) seem to benefit from hematopoietic growth factors whereas this is still unclear for children undergoing therapy for solid tumors. An exciting development is the use of G-CSF and GM-CSF to mobilize peripheral-blood progenitor cells for autologous or allogeneic transplantation. In pediatric patients with hematological diseases, there are only few data on the use of hematopoietic growth factors in children with myelodysplastic syndrome. Experts recommend the early administration of G-CSF in children with very severe aplastic anemia. The use of G-CSF is also recommended in children with severe chronic neutropenia, but these patients have to be monitored regularly for cytogenetic abnormalities. No larger study has shown a clinical benefit of hematopoietic growth factor in preterm or term infants. Future studies in pediatric patients are clearly warranted to address several issues. Prospective clinical trials are still needed to define specific treatment groups who can benefit from growth factor support. In this regard, efforts must be directed at better defining the endpoints and in particular assigning value to reduction in treatment of possible infectious complications, such as days in hospital, antibiotic usage and costs. In addition, randomized studies are required to evaluate the proper dosage and duration of therapy, which most likely will vary between groups of patients. In addition, combinations of different growth factors have to be tested, particularly if ex vivo expansion and the storage of hematopoietic stem cells are to be utilized in a wider spectrum of patients.
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PMID:[Hematopoietic growth factors in prophylaxis and therapy of infections complications in children with neutropenia]. 1152 56

The myelodysplastic syndromes (MDS) are clonal hematological disorders characterized by ineffective hematopoiesis manifested by anemia, neutropenia, thrombocytopenia or a combination. Correction of these cytopenia is a priority in MDS without excess of blasts. Treatment of anemia depends mainly on erythrocyte transfusions. However with the ability of recombinant human hematopoietic growth factor many trials have been promoted. In vitro, erythroid progenitors from MDS patients are able to differentiate but they require much higher concentrations of erythropoietin than normal progenitors. Trials using rHu-Epo alone are disappointing. Combining rHu-Epo and rHu-G-CSF induces more encouraging results showing a synergistic effect particularly clear in sideroblastic anemia. Patients with low endogenous Epo level and low transfusion need are more likely to respond. Clinician should be able in the future to identify MDS patients with a chance of reversal of anemia or transfusion dependency.
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PMID:[The place of growth factors in the treatment of myelodysplastic syndromes]. 1208 72

Anemia resulting from cancer or its treatment is an important clinical problem increasingly treated with the recombinant hematopoietic growth factor erythropoietin. To address uncertainties regarding indications and efficacy, the American Society of Clinical Oncology and the American Society of Hematology developed an evidence-based clinical practice guideline for the use of epoetin in patients with cancer. The guideline panel found good evidence to recommend use of epoetin as a treatment option for patients with chemotherapy-associated anemia with a hemoglobin (Hgb) concentration below 10 g/dL. Use of epoetin for patients with less severe anemia (Hgb level below 12 g/dL but never below 10 g/dL) should be determined by clinical circumstances. Good evidence from clinical trials supports the use of subcutaneous epoetin thrice weekly (150 U/kg) for a minimum of 4 weeks. Less strong evidence supports an alternative weekly (40 000 U/wk) dosing regimen, based on common clinical practice. With either administration schedule, dose escalation should be considered for those not responding to the initial dose. In the absence of response, continuing epoetin beyond 6-8 weeks does not appear to be beneficial. Epoetin should be titrated once the hemoglobin concentration reaches 12 g/dL. Evidence from one randomized controlled trial supports use of epoetin for patients with anemia associated with low-risk myelodysplasia not receiving chemotherapy; however, there are no published high-quality studies to support its use for anemia in other hematologic malignancies in the absence of chemotherapy. Therefore, for anemic patients with hematologic malignancies it is recommended that physicians initiate conventional therapy and observe hematologic response before considering use of epoetin.
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PMID:Use of epoetin in patients with cancer: evidence-based clinical practice guidelines of the American Society of Clinical Oncology and the American Society of Hematology. 1223 38

Anemia resulting from cancer, or its treatment, is an important clinical problem increasingly treated with the recombinant hematopoietic growth factor erythropoietin. To address uncertainties regarding indications and efficacy, the American Society of Clinical Oncology and the American Society of Hematology developed an evidence-based clinical practice guideline for the use of epoetin in patients with cancer. The guideline panel found good evidence to recommend use of epoetin as a treatment option for patients with chemotherapy-associated anemia with a hemoglobin level less than 10 g/dL. Use of epoetin for patients with less severe anemia (hemoglobin < 12 g/dL but never below 10 g/dL) should be determined by clinical circumstances. Good evidence from clinical trials supports the use of subcutaneous epoetin thrice weekly (150 U/kg tiw) for a minimum of 4 weeks. Less strong evidence supports an alternative weekly (40,000 U/wk) dosing regimen, based on common clinical practice. With either administration schedule, dose escalation should be considered for those not responding to the initial dose. In the absence of response, continuing epoetin beyond 6 to 8 weeks does not appear to be beneficial. Epoetin should be titrated once the hemoglobin concentration reaches 12 g/dL. Evidence from one randomized controlled trial supports use of epoetin for patients with anemia associated with low-risk myelodysplasia not receiving chemotherapy; however, there are no published high-quality studies to support its use for anemia in other hematologic malignancies in the absence of chemotherapy. Therefore, for anemic patients with hematologic malignancies, it is recommended that physicians initiate conventional therapy and observe hematologic response before considering use of epoetin.
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PMID:Use of epoetin in patients with cancer: evidence-based clinical practice guidelines of the American Society of Clinical Oncology and the American Society of Hematology. 1277 54

CCAAT enhancer binding protein-alpha (C/EBPalpha) inhibits proliferation in multiple cell types; therefore, we evaluated whether C/EBPalpha-deficient hematopoietic progenitor cells (HPCs) have an increased proliferative potential in vitro and in vivo. In this study we demonstrate that C/EBPalpha(-/-) fetal liver (FL) progenitors are hyperproliferative, show decreased differentiation potential, and show increased self-renewal capacity in response to hematopoietic growth factors (HGFs). There are fewer committed bipotential progenitors in C/EBPalpha(-/-) FL, whereas multipotential progenitors are unaffected. HGF-dependent progenitor cell lines can be derived by directly culturing C/EBPalpha(-/-) FL cells in vitro Hyperproliferative spleen colonies and myelodysplastic syndrome (MDS) are observed in mice reconstituted with C/EBPalpha(-/-) FL cells, indicating progenitor hyperproliferation in vitro and in vivo. C/EBPalpha(-/-) FL lacked macrophage progenitors in vitro and had impaired ability to generate macrophages in vivo. These findings show that C/EBPalpha deficiency results in hyperproliferation of HPCs and a block in the ability of multipotential progenitors to differentiate into bipotential granulocyte/macrophage progenitors and their progeny.
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PMID:C/EBPalpha deficiency results in hyperproliferation of hematopoietic progenitor cells and disrupts macrophage development in vitro and in vivo. 1507 37

Selecting the most appropriate treatment for patients with myelodysplastic syndromes (MDS) requires careful consideration of several factors. Most patients with MDS are in the 7th or later decade of life and often have comorbid health problems influencing treatment tolerance. Poor-prognosis MDS, as indicated by unfavorable cytogenetics or an increased percentage of myeloblasts, warrants more aggressive interventions than more indolent forms, which might remain stable for many years without treatment. The only curative treatment for MDS is allogeneic stem cell transplantation; however, only a small percentage of patients are candidates for this aggressive treatment. Traditional management for most patients with MDS is supportive care with red blood cell and platelet transfusions or hematopoietic growth factor support and antibiotics for infections. More detailed scrutiny of the processes involved in the MDS phenotype has stimulated investigation into identifying alternate therapeutic options that are effective and better tolerated. Herein, we summarize an array of novel treatments in development for the management of MDS.
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PMID:Alternative treatments for myelodysplastic syndromes. 1601 3

In early 2005, several groups of investigators studying myeloid malignancies described a novel somatic point mutation (V617F) in the conserved autoinhibitory pseudokinase domain of the Janus kinase 2 (JAK2) protein, which plays an important role in normal hematopoietic growth factor signaling. The V617F mutation is present in blood and marrow from a large proportion of patients with classic BCR/ABL-negative chronic myeloproliferative disorders and of a few patients with other clonal hematological diseases such as myelodysplastic syndrome, atypical myeloproliferative disorders, and acute myeloid leukemia. The JAK2 V617F mutation causes constitutive activation of the kinase, with deregulated intracellular signaling that mimics continuous hematopoietic growth factor stimulation. Within 7 months of the first electronic publication describing this new mutation, clinical molecular diagnostic laboratories in the United States and Europe began offering JAK2 mutation testing on a fee-for-service basis. Here, I review the various techniques used by research groups and clinical laboratories to detect the genetic mutation underlying JAK2 V617F, including fluorescent dye chemistry sequencing, allele-specific polymerase chain reaction (PCR), real-time PCR, DNA-melting curve analysis, pyrosequencing, and others. I also discuss diagnostic sensitivity, performance, and other practical concerns relevant to the clinical laboratorian in addition to the potential diagnostic utility of JAK2 mutation tests.
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PMID:JAK2 V617F in myeloid disorders: molecular diagnostic techniques and their clinical utility: a paper from the 2005 William Beaumont Hospital Symposium on Molecular Pathology. 1693 78

The myelodysplastic syndromes (MDS) remain challenging to the clinician in terms of diagnosis and management. The diagnosis is essentially one of exclusion in first ruling out other disorders that can also cause peripheral blood/bone marrow cell dysplasia and cytopenias. Recent studies implicate extensive apoptosis as the explanation of the paradoxical observation of marrow hyperplasia, but peripheral blood cytopenia. The clonal nature of MDS places it also at continual risk for transformation to acute leukemia. Predicting overall survival as well as the risk of acute myeloid leukaemia (AML) transformation has been improved by the development of the International Prognostic Scoring System (IPSS). Management of MDS can now be based on the patients respective prognostic subgrouping. Low-risk patients should be considered for hematopoietic growth factor singly or in combination, while high-risk patients should be offered AML-induction therapy or novel therapeutic agents. Common complications are neutropenias with recurrent infections and red cell transfusion dependence. Future advances upon understanding the molecular details of the MDS clone should ultimately improve the care of patients with MDS.
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PMID:The role of apoptosis and current therapeutic challenges in myelodysplastic syndromes. 1958 90

Reduced-intensity conditioning (RIC) umbilical cord blood (UCB) transplantation is increasingly used in hematopoietic stem cell transplantation (HCT) for older and medically unfit patients. Data on the efficacy of HCT after RIC relative to myeloablative conditioning (MAC) are limited. We compared the outcomes of acute myeloid leukemia (AML) patients >18 yrs who received UCB grafts after either RIC or MAC. One hundred nineteen adult patients with AML in complete remission (CR) underwent an UCB transplant after RIC (n =74, 62%) or MAC (n = 45, 38%) between January 2001 and December 2009. Conditioning was either reduced intensity and consisted of cyclophosphamide 50 mg/kg, fludarabine 200 mg/m(2), and total-body irradiation (TBI) 200 cGy or myelablative and consisted for cyclophosphamide 120 mg/kg, fludarabine 75 mg/m(2), and TBI 1200-1320 cGy. All patients received cyclosporine (day -3 to day +180) and mycophenolate mofetil (day -3 to day +45) post-HCT immunosuppression and hematopoietic growth factor. Use of RIC was reserved for patients >45 years (n = 66, 89%) or preexisting severe comorbidities (n = 8, 11%). The 2 groups were similar except for preceding myelodysplastic syndrome (RIC = 28% versus MAC = 4%, P < .01) and age that was dictated by the treatment protocols (median, RIC = 55 years versus MAC = 33years; P < .01). The incidence of neutrophil recovery at day +42 was higher with RIC (94% versus MAC = 82%, P < .1), whereas platelet recovery at the sixth month was similar (RIC = 68% versus MAC = 67%, P = .30). Incidence of grade II-IV acute graft-versus-host disease (aGVHD) (RIC = 47% versus MAC = 67%, P < .01) was decreased with similar incidence of chronic GVHD (cGVHD) (RIC = 30% versus MAC = 34%, P = .43). Median follow-up for survivors was 3.8 and 4.5 years for RIC and MAC, respectively (P = .4). Using RIC, 3-year leukemia-free survival (LFS) was decreased (31% versus MAC = 55%, P = .02) and 3-year relapse incidence was increased (43% versus MAC = 9%, P < .01). Two-year transplant-related mortality (TRM) was similar (RIC = 19% versus MAC = 27%; P = .55). In multivariate analysis, RIC recipients and those in CR2 with CR1 duration <1 year had higher risk of relapse and poorer LFS with no independent predictors of TRM. UCB with RIC extends the use of allogeneic HCT for older and frail patients without excessive TRM with greater benefit for patients in CR1 and CR2 with longer CR1.
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PMID:Effect of conditioning regimen intensity on acute myeloid leukemia outcomes after umbilical cord blood transplantation. 2123 21


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