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MicroRNAs (miRNA) are small non-coding RNA molecules that play critical roles in cell differentiation, proliferation and apoptosis and thus regulate haematopoietic stem cells and committed progenitor cells. We analyzed expressions of miRNAs associated with hematopoietic transformation of myeloid, erythroid and megakaryocytic progenitor cells during haematopoiesis (mir155, mir181a, mir221, mir222, mir223, mir451), in patients with primary myelofibrosis (PMF) ( n = 22), polycythemia vera (PV) ( n = 33), essential thrombocythemia (ET) ( n = 49) and in healthy controls ( n = 40) by quantitate/real time polymerase chain reaction. RT-PCR testing was negative for BCR- ABL1 fusion gene in all the patients. Mir155 was expressed in higher levels in all 3 disorders (p < 0.05). Mir221 was higher especially in ET and PMF group (p < 0.05). Mir222 expression was lower in PV patients (p < 0.05) and higher in ET and PMF patients compared to control group. Mir223 expression was higher in ET and PMF group than control group (p > 0.05). Mir451 levels were lower in all three groups compared to control group (p < 0.05). There was no difference in expression levels of mir181a between groups. JAK2V617F positivity, co-morbidities, drugs, and gender did not affect miRNA expressions. This study holds promise for the future application of these molecules for differential diagnosis and as therapeutic targets in Philadelphia chromosome negative myeloproliferative neoplasms. [ABSTRACT FROM AUTHOR]

Most cases of Noonan syndrome (NS) result from mutations in one of the RAS-MAPK signaling genes, including PTPN11, SOS1, KRAS, NRAS, RAF1, BRAF, SHOC2, MEK1 (MAP2K1), and CBL. Cardiovascular diseases of varying severity, such as pulmonary stenosis and hypertrophic cardiomyopathy (HCM), are common in NS patients. RAF1 mutations are most frequent in NS with HCM, while PTPN11 mutations are also well known. Thr73Ile is a gain-of-function mutation of PTPN11, which has been highly associated with juvenile myelomonocytic leukemia and NS/myeloproliferative disease (MPD), but has not previously been reported in HCM. Here, we report a Japanese female infant with NS carrying the PTPN11 T73I mutation with NS/ MPD, complete atrio-ventricular septal defect, and rapidly progressive HCM. No other HCM-related mutations were detected in PTPN11, RAF1, KRAS, BRAF, and SHOC2. This patient provides additional information regarding the genotype-phenotype correlation for PTPN11 T73I mutation in NS. [ABSTRACT FROM AUTHOR]

Rare patients suffering from myeloid neoplasms share clinical and cytological features indistinguishable from chronic myeloid leukemia (CML) but lack the BCR-ABL1 fusion gene. Several studies provide evidence that alterations in genes encoding tyrosine kinase receptors such as the platelet-derived growth factor receptor ( PDGFR) may be involved in the pathogenesis of these disorders. Here we describe a patient with a rare CML-like disease in whom we identified a novel in-frame BCR-PDGFRA rearrangement joining BCR exon 17 to PDGFRA exon 13, resulting in overexpression of PDGFRA. The design of a specific quantitative PCR assay to monitor the molecular response during treatment with imatinib, a multitargeted tyrosine kinase inhibitor (TKI) with activity against ABL, c-Kit, and PDGFRA revealed an outstanding disease control with durably undetectable BCR-PDGFRA transcripts. Multiple TKIs are currently available yet with distinct target profiles; thus, accurate molecular diagnosis and monitoring tools are essential to establish tailored treatments and assess response to therapy in this type of rare hematological malignancy. [ABSTRACT FROM AUTHOR]

CD4+ T cells maintain cancer surveillance and immune tolerance. Chronic inflammation has been proposed as a driver of clonal evolution in myeloproliferative neoplasms ( MPN), suggesting that T cells play an important role in their pathogenesis. Treatment with JAK inhibitors ( JAKi) results in improvements in MPN-associated constitutional symptoms as well as reductions in splenomegaly. However, effects of JAKi on T cells in MPN are not well established and the baseline immune signature remains unclear. We investigated the frequency and function of CD4+ T cell subsets in 50 MPN patients at baseline as well as during treatment with either ruxolitinib or fedratinib in a subset. We show that CD4+ CD127low CD25high FOXP3+ T regulatory cells are reduced in MPN patients compared to healthy controls and that this decrease is even more pronounced following JAKi therapy. Moreover, we show that after 6 months of treatment the number of T helper (Th)-17 cells increased. We also describe a functional 'silencing' of T helper cells both in vivo and in vitro and a blockade of pro-inflammatory cytokines from these cells. This profound effect of JAKi on T cell function may underlay augmented rates of atypical infections that have been reported with use of these drugs. [ABSTRACT FROM AUTHOR]

A subset of Down syndrome (DS) (trisomy 21) neonates is born with a unique erythromegakaryocytic myeloproliferative disorder that spontaneously resolves over the first few months of life (DS-transient abnormal myelopoiesis (DS-TAM); previously called DS-transient myeloproliferative disorder (DS-TMD) and DS-transient leukemia (DS-TL)). These infants are at high risk for developing subsequent acute megakaryoblastic leukemia (myeloid leukemia associated with Down syndrome (ML-DS); previously called DS-acute megakaryoblastic leukemia (DS-AMKL)). The molecular basis for DS-TAM/ML-DS remained mysterious for a long period of time. However, new genetic insights have been gained over the past 12 years that have begun to decipher the pathophysiology of this unusual disorder. [ABSTRACT FROM AUTHOR]

Zebrafish is an established model for the study of vertebrate development, and is especially amenable for investigating hematopoiesis, where there is strong conservation of key lineages, genes, and developmental processes with humans. Over recent years, zebrafish has been increasingly utilized as a model for a range of human hematopoietic diseases, including malignancies. This review provides an overview of zebrafish hematopoiesis and describes its application as a model of leukemia and other hematopoietic disorders. [ABSTRACT FROM AUTHOR]

Background Immunophenotyping has replaced cytochemical staining as the preferred technique for classifying acute leukemia. However, some acute myeloid leukemias ( AML) lack lineage-associated markers. In our experience, alkaline phosphatase ( ALP) is expressed in immature canine monocytes. We hypothesized that ALP is a useful marker for monocytic AML. Objectives The objective was to compare ALP expression in neoplastic cells from dogs with lymphoma, chronic lymphocytic leukemia ( CLL), acute lymphoid leukemia ( ALL), and AML. Methods Alkaline phosphatase results were retrieved from medical records of dogs with acute leukemia. Smears from dogs with lymphoma or leukemia were also prospectively stained for ALP activity. CLL was based on persistent lymphocytosis (10 × 109/L) and acute leukemia on ≥ 20% blasts in blood or bone marrow. ALL was classified based on positive phenotyping for T- or B-lymphocyte antigens, and AML on positive phenotyping for CD11b, CD11c or CD14, or cytochemical staining for chloroacetate esterase, Sudan Black B, or myeloperoxidase. Results There was no ALP activity in all 49 lymphomas and 7 CLLs. Weak ALP activity was seen in 31% of 14 ALL (all T-ALL). ALP activity was seen in all 20 AML ( P < .001 vs ALL) with strong activity in 64% (vs 25% ALL) in most neoplastic cells (median 75% vs 9% ALL, P = .020). Of AML, 80% were CD34+ (vs 39% ALL, P = .027) and 100% were MHCII− (vs 43% ALL, P = .002). Conclusions ALP activity may be useful for AML confirmation in dogs, particularly if neoplastic cells only express CD34+ on immunophenotyping. [ABSTRACT FROM AUTHOR]

A case of granulocytic sarcoma of skin and lymph nodes is reported in a 65-year-old man as an initial presentation of a myeloproliferative disorder, chiefly involving myelofibrosis. The symptoms, physical examination, hematological findings, imunohistochemistry and anatomopathological results and evolution of the disease are described. As this is an unusual case, stress was placed on the diagnostic confusion that may occur.

Essential thrombocythemia is a rare myeloproliferative disorder in pediatrics. This myeloproliferative disorder is charactherized by thrombocytosis and hyperplasia of megakaryocytes in the bone marrow. Other cell lines are not involved.JAK2V617Fmutations has been identified in approximately half the patients with this disorder. We describe a 12-year-old boy with essential throbocythemia. The patient had a persistent thrombocytosis over 600x109 /L and the time of diagnosis, his platelet count ranged between 900x109and 2150x109/L. Megakaryocytes in the bone marrow were increased in number. The chromosomal analysis was normal and bcr/abl rearrangement was negative. He remained asymptomatic throughout the follow-up period.

Introduction: Chronic myeloid leukemia (CML) is a progressive myeloproliferative disorder resulting from forming a chimeric BCR-ABL gene. The proteins derived from this gene can affect some genes from various signaling pathways such as PI3K/AKT/Wnt/catenin/JAK/Stat involved in proliferation, differentiation, cell death, and genes related to autophagy. Imatinib is the first-line treatment for CML patients, with durable and proper responses in Iranian children and adult CML patients. Hence, we aimed to evaluate the mRNA expression of some selected key genes from those pathways in patients with CML before and under treatment., Methods: In the case-control study, the mRNA expression of PTEN, LEF1, JAK3, LC3 and p62 genes were measured in 51 CML patients (6 patients before treatment and 45 patients under treatment with imatinib mesylate) and 40 healthy controls using the Real-time PCR method., Results: The mRNA expression of PTEN and P62 were significantly higher in newly diagnosed patients than in controls (P<0.0001 and P = 0.0183, respectively), while the expression of the LC3 gene was significantly lower in the untreated newly diagnosed group than in control subjects (P = 0.0191). The expression level of PTEN, LEF1, JAK3 and P62 genes were significantly decreased in patients under treatment than in the group before treatment (P = 0.0172, P = 0.0002, P = 0.0047 and P = 0.0038, respectively). A positive correlation was seen between the gene expression of P62 and BCR-ABL in the patients under treatment (r 0529, P = 0.016)., Conclusion: Our findings showed that the changes in expression of these genes were related to the patient's treatment. Due to the key role of these genes in proliferation, differentiation and tumor suppression, it is proposed that these genes may be helpful for follow-up of treatment in CML patients., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Primary familial and congenital polycythaemia ( PFCP) is a disease characterized by increased red blood cell mass, and can be associated with mutations in the intracellular region of the erythropoietin ( EPO) receptor ( EPOR). Here we explore the mechanisms by which EPOR mutations induce PFCP, using an experimental system based on chimeric receptors between epidermal growth factor receptor ( EGFR) and EPOR. The design of the chimeras enabled EPOR signalling to be triggered by EGF binding. Using this system we analysed three novel EPOR mutations discovered in PFCP patients: a deletion mutation (Del1377-1411), a nonsense mutation (C1370A) and a missense mutation (G1445A). Three different chimeras, bearing these mutations in the cytosolic, EPOR region were generated; Hence, the differences in the chimera-related effects are specifically attributed to the mutations. The results show that the different mutations affect various aspects related to the signalling and metabolism of the chimeric receptors. These include slower degradation rate, higher levels of glycan-mature chimeric receptors, increased sensitivity to low levels of EGF (replacing EPO in this system) and extended signalling cascades. This study provides a novel experimental system to study polycythaemia-inducing mutations in the EPOR, and sheds new light on underlying mechanisms of EPOR over-activation in PFCP patients. [ABSTRACT FROM AUTHOR]

Highlights: [•] ADAM10 deficiency leads to the development of a myeloproliferative disorder. [•] Bone marrow transplantation experiments strongly support a non-cell autonomous origin. [•] A central role of ADAM10 for the regulation of granulopoiesis and lymphopoiesis is suggested. [ABSTRACT FROM AUTHOR]

Abstract: Rap proteins (Rap1, Rap2a, b, c) are small molecular weight GTPases of the Ras family. Rap G proteins mediate diverse cellular events such as cell adhesion, proliferation, and gene activation through various signaling pathways. Activation of Rap signal is regulated tightly by several specific regulatory proteins including guanine nucleotide exchange factors and GTPase-activating proteins. Beyond cell biological studies, increasing attempts have been made in the past decade to define the roles of Rap signal in specific functions of normal tissue systems as well as in cancer. In the immune and hematopoietic systems, Rap signal plays crucial roles in the development and function of essentially all lineages of lymphocytes and hematopoietic cells, and importantly, deregulated Rap signal may lead to unique pathological conditions depending on the affected cell types, including various types of leukemia and autoimmunity. The phenotypical studies have unveiled novel, even unexpected functional aspects of Rap signal in cells from a variety of tissues, providing potentially important clues for controlling human diseases, including malignancy. [Copyright &y& Elsevier]

Patients with thrombophilic disorder while undergoing intra-abdominal surgery may develop splanchnic vein thrombosis which can have dire consequences. Here we report a case of a 38-year-old female who developed acute Budd–Chiari syndrome after a laparoscopic cholecystectomy. She had polycythemia vera which was not diagnosed before surgery. In this report we want to highlight presurgical evaluation of routine biochemical tests and ultrasonography suggestive of myeloproliferative disorders were missed which led to the Budd–Chiari syndrome. We recommend a meticulous look at the routine evaluation done prior to cholecystectomy is essential. [ABSTRACT FROM AUTHOR]

This presentation is a clinical narrative and long term follow up (6-16 years) of 21 prospectively studied patients with essential thrombocythaemia (ET) in Kuwait. The median age (55.9 years) is younger than reported by others. Two patients were below the age of 40 years with one of them presenting as post-polycytheamia ET at 16 years of age. Twelve patients (57.1 %) remained asymptomatic throughout the period of follow up. Four patients complained of erythromelalgia, three (19 %) suffered from thrombotic episodes and only one (4.3 %) had excessive bleeding. Four patients presented with splenomegaly. Intensity of thrombocytosis or duration of very high platelet count had no relationship with these complications. Two patients transformed to post-ET myelofibrosis and one patient developed chronic myeloid leukaemia (CML). None transitioned to acute leukaemia. All patients are still alive after follow up for 6-16 years. Janus kinase 2 mutation was positive in eight (38 %) patients. It had no bearing on transition of our ET patients to post-ET myelofibrosis or CML. Platelet aggregation tests were performed in 14 patients. Six (42.9 %) showed defective response to ADP. Only one of these patients suffered from bleeding. All patients were given aspirin (81 mg/day). Cyto-reductive therapy with hydroxyurea was taken by six (42.9 %) subjects. Two patients who were treated with anagrelide and one with alpha-interferon did not continue treatment for long. [ABSTRACT FROM AUTHOR]

Résumé: La découverte d’une thrombocytose est un événement fréquemment rencontré lors de la réalisation d’un hémogramme. Cette anomalie est souvent d’origine secondaire et ne donne alors pas lieu à des complications thrombotiques. Si une cause réactionnelle est éliminée, la thrombocytose est primitive, rarement d’origine héréditaire mais est le plus souvent associée à une hémopathie maligne. Il faut alors savoir reconnaître une éventuelle thrombocytémie essentielle, en éliminant les diagnostics différentiels que sont certains syndromes myélodysplasiques et les autres syndromes myéloprolifératifs. Son traitement repose sur la prévention des risques thrombotiques et l’introduction éventuelle d’un traitement cytoréducteur. L’espérance de vie est sensiblement identique à celle de la population générale et dépend principalement de la survenue d’une myélofibrose ou de la transformation en leucémie aiguë myéloïde. [ABSTRACT FROM AUTHOR]

The discovery of the highly prevalent activating JAK (Janus kinase) 2 V617F mutation in myeloproliferative neoplasms, and of other pseudokinase domain-activating mutations in JAK2, JAK1 and JAK3 in blood cancers, prompted great interest in understanding how pseudokinase domains regulate kinase domains in JAKs. Recent functional and mutagenesis studies identified residues required for the V617F mutation to induce activation. Several X-ray crystal structures of either kinase or pseudokinase domains including the V617F mutant of JAK2 pseudokinase domains are now available, and a picture has emerged whereby the V617F mutation induces a defined conformational change around helix C of JH (JAK homology) 2. Effects of mutations on JAK2 can be extrapolated to JAK1 and TYK2 (tyrosine kinase 2), whereas JAK3 appears to be different. More structural information of the full-length JAK coupled to cytokine receptors might be required in order to define the structural basis of JH1 activation by JH2 mutants and eventually obtain mutant-specific inhibitors. [ABSTRACT FROM AUTHOR]

Acute myeloid leukemia (AML) is an uncommon, but often deadly complication of myeloproliferative neoplasms (MPN). Post-MPN AML usually occurs years after the initial MPN diagnosis with an average age of onset between 64 and 68 years. Chromosome abnormalities are common and many patients have cytogenetic changes that are associated with poor risk features. Post-MPN AML is characterized by acquired somatic gene mutations, but, interestingly, mutations thought to have an etiologic role in the MPN, such as JAK2V617F, are sometimes absent in the AML clone. Conventional AML-style treatment appears to have limited efficacy, although when coupled to allogeneic stem cell transplantation, some patients have long-term survival. Less-intensive therapies such as hypomethylating agents and the JAK inhibitor, ruxolitinib, may be effective in some patients. New treatments have prompted efforts to characterize therapeutic responses better. [ABSTRACT FROM AUTHOR]

A male patient with a persistent, combined erythrocytosis, leukocytosis, and thrombocytosis without representative evidence of reactive increase emerged as having a myeloproliferative disorder. Molecular-biological assessment yielded Janus kinase 2-positive results, and the patient was diagnosed with polycythemia vera. In addition to these findings, further karyotyping accounted for a Robertsonian translocation. Because this rearrangement was a balanced variant, we concluded that this cytogenetic result might not significantly alter the diagnosis of polycythemia vera., (© The Author(s) 2021. Published by Oxford University Press on behalf of American Society for Clinical Pathology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

The classical BCR-ABL negative myeloproliferative neoplasms (MPN) polycythemia vera, essential thrombocythemia, and primary myelofibrosis are clonal hematopoietic disorders characterized by excessive production of terminally differentiated myeloid cells. In MPN patients, the disease can progress to secondary myelofibrosis or acute myeloid leukemia. Clonal hematopoiesis, disease phenotype, and progression are caused by somatically acquired genetic lesions of genes involved in cytokine signaling, RNA splicing, as well as epigenetic regulation. This review provides an overview of point mutations and cytogenetic lesions associated with MPN and addresses the role of these somatic lesions in MPN disease progression. [ABSTRACT FROM AUTHOR]

The JAK2 V617 F somatic mutation is present in the majority of patients with myeloproliferative cancer (polycythaemia vera, essential thrombocytosis, and primary myelofibrosis). However, the diagnostic value of the JAK2 V617 F somatic mutation for myeloproliferative cancer in the general population is unknown. We examined this question in 49 488 individuals from the Copenhagen General Population Study. We also examined the association between JAK2 V617 F somatic mutation, rs10974944 germline genotype, haematological phenotype, any cancer, haematological cancer, myeloproliferative cancer, ischaemic heart disease, and venous thromboembolism. The JAK2 V617 F somatic mutation was present in 0·1% ( n = 68), increasing across rs10974944 germline genotypes ( P-trend = 0·001). JAK2 V617 F somatic mutation positives versus negatives had higher erythrocyte ( P = 2 × 10−5), thrombocyte ( P = 2 × 10−16), and leucocyte ( P = 4 × 10−9) counts, and had 2·7-/2·5-fold risk of cancer (prevalent/incident), 44-/28-fold risk of haematological cancer, 221-/97-fold risk of myeloproliferative cancer, 2·2-/1·2-fold risk of ischaemic heart disease, and 3·1-/1·0-fold risk of venous thromboembolism. By combining conventional haematological parameters with a test for the JAK2 V617 F somatic mutation, myelo;?>proliferative cancer could be identified or ruled out with a sensitivity of 47-100% and a specificity of 98-100%. In conclusion, in the general population the JAK2 V617 F somatic mutation has a high diagnostic value for myeloproliferative cancer when combined with conventional haematological parameters. [ABSTRACT FROM AUTHOR]

Abstract: We treated 37 patients with polycythemia vera with imatinib mesylate (IM). The overall response rate was 49%. Thirty percent had a complete response, and 19%, a partial response. Thirty-one patients were treated for >120days. Frequent side effects included nausea, diarrhea, edema, and skin rash. Whereas IM was effective in controlling erythropoiesis and reducing spleen size it was ineffective in controlling thrombocytosis. Normocellular marrow developed in 4 patients who had a complete response. Progression to overt myelofibrosis occurred in 3. Nevertheless, 6 patients have had a sustained complete response while on IM for >6years. These patients were young, had high phlebotomy requirements, and only slightly elevated platelet counts. Therefore, we believe there may be a role for IM in patients with these characteristics whose disease cannot be controlled by, or as an alternative to, other myelosuppressive treatments. [Copyright &y& Elsevier]

Abstract: The classical myeloproliferative neoplasms (MPNs) feature an overproduction of mature blood elements. Phenotypic conversion, including transformation to myelofibrosis (MF) in those with antecedent ET and PV is a feared complication. Hypereosinophilic syndromes (HESs), especially those with myeloproliferative variants, can display similar features, including organomegaly, marrow fibrosis, clonality, thrombotic tendencies, and acute myeloid leukemia (AML) transformation. However, this group of illnesses is typically clinically and molecularly distinct from the classical MPNs. We report a case of a 59-yr-old woman with complex hypereosinophilia in the setting of post-polycythemic myelofibrosis (post-PVMF), with multi-system end-organ damage characteristic of HES. [Copyright &y& Elsevier]

We analyzed complete blood count (CBC) data obtained from neonates with Down syndrome (DS) in a primarily Hispanic population over a 10-year period to determine the incidence of hematologic abnormalities and the relationship of abnormalities to the presence of circulating blasts (CB). Hematologic values obtained during the first 10 days were analyzed. Definitions were: CB, ≥1% blasts manually counted on peripheral smear; elevated white blood cell count (WBC), >30,000 cells/mm3; thrombocytopenia, platelet count <150,000/mm3; polycythemia, hematocrit >65%. Two hundred thirty-two neonates (88% Hispanic) with DS had 692 CBCs available for analysis. The presence of CB (11.6%) and the incidence of thrombocytopenia (60.2%) were significantly higher in DS neonates than in the reference group. Elevated WBC (33.3%) and thrombocytopenia (84.6%) were more common in DS neonates with CB versus those with no CB. No relationship between thrombocytopenia and polycythemia was observed. Unlike previous reports, we did not observe a male predominance in those DS neonates with CB. Thrombocytopenia occurred frequently in DS neonates and was significantly more likely in those with CB than in those with no CB. CBC screening should be performed routinely in DS neonates. [ABSTRACT FROM AUTHOR]

Abstract: The disruption of Janus kinase 2 (JAK2) signaling regulation by its point mutation, V617F, is involved in various myeloproliferative disorders (MPDs). JAK2 V617F mutant induced constitutive activation of Akt when erythropoietin receptor (EpoR) was coexpressed; however, the physiological role of Akt activation in MPDs has not been elucidated. LY294002, a phosphoinositide 3-kinase (PI3K) inhibitor, inhibited Akt activation and induced apoptotic cell death in cells expressing JAK2 V617F mutant and EpoR. Previously, it has been shown that the phosphorylation at Y479 in EpoR is critical for the interaction with PI3K, an upstream molecule of Akt. Hence, EpoR mutant with a point mutation of Y479F, which fails to activate Akt, is useful for addressing the role of Akt activation in JAK2 V617F mutant-induced tumorigenesis. Interestingly, under the expression of EpoR Y479F mutant, JAK2 V617F mutant failed to exhibit potent anti-apoptotic activity. In addition, JAK2 V617F mutant-induced phosphorylation of CREB and GSK-3β was significantly decreased in cells expressing EpoR Y479F mutant, resulting in the downregulation of Bcl-XL and Mcl-1 expression. Furthermore, compared with when nude mice were inoculated with cells expressing JAK2 V617F mutant and EpoR, the lifespan of nude mice inoculated with cells expressing JAK2 V617F mutant and EpoR Y479F mutant was effectively prolonged. Taken together, it was clarified that PI3K-Akt activation through the phosphorylation of EpoR at Y479 is required for oncogenic signaling of JAK2 V617F mutant and that targeted disruption of this pathway has therapeutic utility. [Copyright &y& Elsevier]

Myeloid neoplasms derive from the pathological clonal expansion of an abnormal stem cell and span a diverse spectrum of phenotypes including acute myeloid leukaemia (AML), myeloproliferative neoplasms (MPN) and myelodysplastic syndromes (MDS). Expansion of myeloid blasts with suppression of normal haematopoiesis is the hallmark of AML, whereas MPN is associated with over-proliferation of one or more lineages that retain the capacity to differentiate, and MDS is characterized by cytopenias and aberrant differentiation. MPD and MDS can progress to AML, which is likely due to the acquisition of cooperative mutations. Juvenile myelomonocytic leukaemia (JMML) is an aggressive myeloid neoplasm of childhood that is clinically characterized by overproduction of monocytic cells that can infiltrate organs, including the spleen, liver, gastrointestinal tract, and lung. JMML is categorized as an overlap MPN/MDS by the World Health Organization and also shares some clinical and molecular features with chronic myelomonocytic leukaemia, a similar disease in adults. While the current standard of care for patients with JMML relies on allogeneic haematopoietic stem cell transplant (HSCT), relapse is the most frequent cause of treatment failure. This review outlines our understanding of the genetic underpinnings of JMML with a recent update on the discovery of novel CBL mutations, as well as a brief review on current therapeutic approaches. [ABSTRACT FROM AUTHOR]

A 9-year-old female spayed mixed breed dog was evaluated at the University of Florida Small Animal Hospital for marked leukocytosis with no associated clinical signs. CBC abnormalities included marked leukocytosis (106,000/μL), marked monocytosis (78,000/μL), and the presence of 13% blast cells (13,832/μL), supporting a diagnosis of leukemia. Cytopenias and dysplastic changes in other cell lines were not present. Microscopic examination of bone marrow showed hypercellular uniparticles with a marginal increase in frequency of unclassified blast cells (2%), but was otherwise unremarkable. Flow cytometric immunophenotyping of blood cells determined that leukemic cells were CD45, CD14, and CD34, and based on side scatter and CD45 reactivity the marrow contained 19% monoblasts. By immunocytochemical staining, the leukemic cells in the bone marrow were CD11b, CD11c, CD11d, MHC-II, MPO, and CD34. Fluorescence in situ hybridization (FISH) analysis of peripheral blood leukocytes documented a chromosomal translocation producing a BCR-ABL gene hybrid, similar to the 'Philadelphia' chromosome abnormality recognized in human chronic myelogenous leukemia, as well as a phosphatase and tensin homolog (PTEN) gene deletion. Hydroxyurea therapy was attempted, but was ineffective; the dog died 7 months after initial presentation. Clinical and laboratory findings and the protracted course supported a diagnosis of chronic monocytic leukemia (CMoL) and, to our knowledge, this is the first case of CMoL with a BCR-ABL chromosomal abnormalitiy described in dogs. This may have clinical implications for treatment of dogs with chronic leukemias associated with particular genetic mutations. However, more case studies are needed to further characterize this disease. [ABSTRACT FROM AUTHOR]

Abstract: Myelofibrosis (MF) is a clonal stem cell disorder with the potential to transform to acute leukemia, referred to as myelofibrosis in blast phase (MF-BP). The outcome of patients with MF-BP is grave with a median survival of only 2.7 months. MF-BP is largely refractory to conventional chemotherapy and intensive induction therapy fails to have a significant impact with a median survival of 3.9 months. Eleven consecutive patients were treated at our institution with MF-BP over a 2-year period. Eligible patients with an available donor received an allogeneic stem cell transplant (ASCT) and those that were not eligible or without a donor were treated with Decitabine (DEC). The median time for follow up for the entire group was 9 months (range 5–21 month). At 9 months (range 5–45 months), 67% of the patients treated with DEC were alive and at 20 months (range 9–23 months), 53% of patients treated with ASCT remain alive. Reduced intensity conditioning allogeneic stem cell transplantation (RIC-ASCT) is a viable option that offers the potential for prolonged survival and the possibility of cure for patients with MF-BP. DEC is a tolerable outpatient chemotherapeutic regimen for MF-BP patients ineligible for transplant and deserves further prospective study. [ABSTRACT FROM AUTHOR]

Constitutive activation of Janus kinase (Jak) 2 is the most prevalent pathogenic event observed in the myeloproliferative disorders (MPD), suggesting that inhibitors of Jak2 may prove valuable in their management. Inhibition of the Aurora kinases has also proven to be an effective therapeutic strategy in a number of haematological malignancies. AT9283 is a multi-targeted kinase inhibitor with potent activity against Jak2 and Aurora kinases A and B, and is currently being evaluated in clinical trials. To investigate the therapeutic potential of AT9283 in the MPD we studied its activity in a number of Jak2-dependent systems. AT9283 potently inhibited proliferation and Jak2-related signalling in Jak2-dependent cell lines as well as inhibiting the formation of erythroid colonies from haematopoietic progenitors isolated from MPD patients with Jak2 mutations. The compound also demonstrated significant therapeutic potential in vivo in an ETV6-JAK2 ( TEL-JAK2) murine leukaemia model. Inhibition of both Jak2 and Aurora B was observed in the model systems used, indicating a dual mechanism of action. Our results suggest that AT9283 may be a valuable therapy in patients with MPD and that the dual inhibition of Jak2 and the Aurora kinases may potentially offer combinatorial efficacy in the treatment of these diseases. [ABSTRACT FROM AUTHOR]

The article presents information on investigation and management of adults and children presenting with a thrombocytosis. It is stated that the most common secondary causes of thrombocytosis are infection, inflammation, iron deficiency, tissue damage, haemolysis, severe exercise, malignancy, hyposplenism and other causes of an acute phase. It is stated that limitation of life expectancy is a major concern for many patients with essential thrombocythaemia (ET)

Managing patients with myelofibrosis (MF)—either those with primary MF or those whose MF has evolved from antecedent polycythemia vera or essential thrombocythemia—presents many challenges to the hematologist. Cure is potentially achievable through allogeneic stem cell transplantation, but this therapy is either inappropriate or not feasible for most patients. MF patients suffer from a range of debilitating disease manifestations (eg, massive splenomegaly, cytopenias, constitutional symptoms, and transformation to a treatment-refractory blast phase). Currently available therapies are palliative but can be of significant value to some MF patients for anemia, splenomegaly, or sometimes both manifestations. New medical therapies for MF revolve around three main themes: immunomodulation (to assist anemia), hypomethylation strategies, and (the most robust pipeline) the use of targeted JAK2 inhibitors. These latter agents have shown the ability to improve MF-associated splenomegaly and MF-associated symptoms but do not improve (and may exacerbate) anemia or thrombocytopenia. Future targeted agents, and perhaps combinations of agents that currently show complementary benefits, are anticipated to further enhance the efficacy of medical therapy for MF. [ABSTRACT FROM AUTHOR]

The article reports on an adult patient who presented with a thrombocytosis with no causes of reactive elevation of platelet counts and no mutation in genetic transcript. MPL gene sequencing led to the discovery of two different MPL heterozygous variants. The K39N variant, also called the Baltimore polymorphism, is linked to thrombocytosis when present in a homozygous state. DNA from the patient showed the heterozygous status and germline origin of both the K39N variant and the MPL mutation.

Abstract: Background: Janus kinase 2 (JAK2) is a tyrosine kinase involved in the cytokine signaling of several growth factors such as erythropoietin and thrombopoietin in normal and neoplastic cells. The G to T exchange at nucleotide 1849 in exon 14 of the JAK2 gene leads to a substitution of valine with phenylalanine at the amino acid position 617 (V617F) of the JAK2 protein. Currently, the occurrence of the JAK2 V617F mutation is well recognized in chronic myeloproliferative disorders (MPDs). Methods: We identified JAK2 V617F missense mutation in patients with MPD by high resolution melting (HRM) analysis. HRM analysis is a new gene scan tool that quickly performs the PCR and identifies sequences alterations without requiring post-PCR treatment. This study included 7 PV patients (41.1%), 6 ET patients (35.3%), and 4 myelofibrosis patients (23.5%). Additionally, our methodology was compared with amplification refractory mutation system (ARMS) assay. Results: Up to 5% of the JAK2 V617F mutation was successfully detected in patients with MPD using HRM analysis. Eleven out of 17 patients (64.7%) were positive for the presence of JAK2 V617F mutation. The prevalence of mutation in the different subtypes of MPDs was 85.7% in PV (6 of 7 patients), 66.7% in ET (4 of 6) and 5.9% in myelofibrosis (1 of 4). The results proved 100% comparable to those obtained by ARMS assay. Conclusions: The HRM analysis is a rapid and effective technique for the detection of JAK2 V617F missense mutation. [Copyright &y& Elsevier]

Abstract: Quality of life (QoL) in patients with myelofibrosis (MF) is severely compromised by severe constitutional symptoms (i.e. fatigue, night sweats, fever, weight loss), pruritus, and symptoms from frequently massive hepatosplenomegaly. Given that no current instrument of patient reported outcomes (PRO) exists that covers the unique spectrum of symptomatology seen in MF patients, we sought to develop a new PRO instrument for MF patients for use in therapeutic clinical trials. Utilizing data from an international Internet-based survey of 458 patients with MF we created a 20-item instrument (MFSAF: Myelofibrosis Symptom Assessment Form) which measures the symptoms reported by >10% of MF patients and includes a measure of QoL. We subsequently validated the MFSAF in a prospective trial of MF patients involving patient and provider feedback, as well as comparison to other validated instruments used in cancer patients. The MFSAF results were highly correlated with other instruments, judged comprehensive and understandable by patients, and should be considered for evaluation of MF symptoms in therapeutic trials. [Copyright &y& Elsevier]

Murine haematopoietic stem cells (HSCs) are contained in the Kit+Sca1+Lin− (KSL) population of bone marrow and are able to repopulate lethally irradiated mice. Myeloproliferative disorders (MPDs) are thought to be clonogenic diseases arising at the level of the HSC. Here, we show that mice expressing low levels of the transcription factor c-Myb, as the result of genetic knockdown, develop a transplantable myeloproliferative phenotype that closely resembles the human disease essential thrombocythaemia (ET). Unlike wild-type cells, the KSL population in c-myb knockdown bone marrow cannot repopulate irradiated mice and does not transfer the disease. Instead, cells positive for Kit and expressing low to medium levels of CD11b acquire self-renewing stem cell properties and are responsible for the perpetuation of the myeloproliferative phenotype. [ABSTRACT FROM AUTHOR]

This study looked for clonal diversity in patients with a myeloproliferative neoplasm associated with more than one acquired genetic lesion. A tyrosine kinase mutation and a cytogenetic lesion were present in the same clone in six of seven patients. By contrast, the genetic lesions were present in separate clones in all six patients with two tyrosine kinase pathway mutations. Moreover, in two patients the clones were genetically unrelated by X-chromosome inactivation studies. These data demonstrated clonal diversity in a subset of patients with early stage haematopoietic malignancy and showed, for the first time, that such clones may arise independently. [ABSTRACT FROM AUTHOR]