Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0023473 (chronic myeloid leukemia)
 18,916 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The recently described JAK2 V617F mutation, present in a substantial proportion of nonchronic myelogenous leukemia chronic myeloproliferative disorders (non-CML CMPDs), is changing the way we conceptualize and diagnose these diseases. We hypothesized that the activation of this tyrosine kinase might result in activation of downstream mediators such as STAT5, which would be detectable in bone marrow biopsies. We examined the expression of activated STAT5 (nuclear phospho-STAT5) in 73 bone marrow biopsies from patients with CMPDs [20 essential thrombocythemia (ET), 26 chronic idiopathic myelofibrosis (CIMF), and 27 polycythemia vera] and 39 controls. We compared the results with the JAK2 mutational status and clinical parameters. The frequency of the JAK2 V617F was 73% (85% in PV, 65% in ET, and 65% in CIMF). All patients with the JAK2 V617F showed abnormal nuclear megakaryocytic phospho-STAT5 (nMEG pSTAT5) expression. In the JAK2 wild-type group, nMEG pSTAT5 was observed in 2/7 ET, and 3/9 CIMF patients. nMEG pSTAT5 staining was 100% sensitive and 88% specific for JAK2 V617F. Clinically, nMEG pSTAT5+ patients seemed to require cytoreductive therapy more often than those without nMEG p-STAT expression. pSTAT5 immunohistochemistry is a useful diagnostic test in bone marrow biopsies from suspected non-CML CMPD patients. It identifies most of the patients with the JAK2 V617F but also other JAK2 wild-type CMPD patients. The presence of nMEG pSTAT5 in a subset of CMPD patients lacking the mutation suggests that alternate tyrosine kinase/phosphatase pathways may be involved and warrant further investigation. Phosphoprotein detection represents a new area for diagnostic pathology that exploits specific functional characteristics of cells within the context of a tissue section.
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PMID:Bone marrow phospho-STAT5 expression in non-CML chronic myeloproliferative disorders correlates with JAK2 V617F mutation and provides evidence of in vivo JAK2 activation. 1725 68

Philadelphia chromosome-negative chronic myeloproliferative disorders (Ph(-) CMPD) comprise a group of heterogenous haematological stem cell disorders. These diseases harbour a pathological bone marrow stem cell which overwhelms normal stem cells due to sustained and uncontrolled proliferation. By clonal evolution, acute leukaemia or bone marrow fibrosis evolve in a proportion of cases with as yet unknown underlying mechanisms. Previously, groundbreaking investigations in Ph(-) CMPD detected an acquired mutation in the Janus kinase 2 (JAK2) in the majority of patients with polycythaemia vera (PV) and in up to 50% of patients with essential thrombocythaemia (ET) and chronic idiopathic myelofibrosis (CIMF). Unlike the stem cell defect in Philadelphia chromosome-positive chronic myeloid leukaemia only a subfraction of clonally proliferating haematopoiesis may be affected by the JAK2 mutation. More recently, another mutation in the juxtamembrane domain of the thrombopoietin receptor Mpl was discovered in about 5% of patients with CIMF and ET. In accordance with the uncontrolled Abl kinase activity in Ph(+) chronic myloid leukaemia these mutations in Ph(-) CMPD apparently represent a key to unlock some of the as yet unknown basic molecular defects and this raises hope for an upcoming efficient targeted therapy. However, neither the JAK2(V617F) nor the Mpl(W515L/K) provide the initiating molecular events. Moreover, apart from distinction between reactive and neoplastic lesions, detection of these mutations does not allow a clear-cut discrimination between the particular subtypes. This review will focus on previous and recent findings in the field of molecular defects in Ph(-) CMPD.
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PMID:Stem cell defects in Philadelphia chromosome negative chronic myeloproliferative disorders: a phenotypic and molecular puzzle? 1822 Sep 9

BACKGROUND Essential thrombocythemia (ET) is one of the BCR-ABL gene fusion negative chronic myeloproliferative disorders (MPDs), which also include polycythemia vera (PV), and myelofibrosis. Few clinical cases have reported the progression of ET to chronic myelogenous leukemia (CML) with the expression of the BCR-ABL gene. This report describes such a case and includes a review of other reported cases of CML co-occurring with BCR-ABL-negative chronic MPDs. CASE REPORT A 49-year-old woman was diagnosed with ET in 2007. Cytogenetic testing was negative for expression of the JAK2 or BCR-ABL1 genes. Eight years later, in January 2015, she presented with excessive fatigue, poor appetite, unintentional weight loss, a white blood cell (WBC) count of 24,700 per mL, hemoglobin of 9.9 g/dl, and a platelet count of 557,000 per mL, with blasts and basophils in the blood film. Cytogenetic analysis with fluorescent in situ hybridization (FISH) confirmed a 9: 22 chromosomal translocation (Philadelphia chromosome), and quantitative reverse transcription polymerase chain reaction (qRT-PCR) detected the expression of the BCR-ABL gene, confirming a diagnosis of CML. In February 2015, first-line therapy commenced with nilotinib, which was changed to imatinib after three months. During the following nine months, qRT-PCR confirmed a trend to deep molecular remission (MR5). However, she developed early myelofibrosis, and myelosuppressive therapy was resumed. CONCLUSIONS This rare case highlights the importance of cytogenetic testing in cases of CMPD that transform to CML, not only to confirm the diagnosis but to plan treatment, as Philadelphia chromosome-positive and -negative cases differ in their management.
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PMID:A Case of Chronic Myelogenous Leukemia Occurring in a Patient Treated for Essential Thrombocythemia. 3060 17


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