A Favorable Outcome In Children with Juvenile Myelomonocytic Leukemia (JMML) with RAS Mutations

Abstract Abstract 2909 Introduction: Juvenile myelomonocytic leukemia (JMML) is a rare clonal myeloproliferative disorder that affects young children. It is characterized by a specific hypersensitivity of JMML cells to granulocyte-macrophage colony-stimulating factor (GM-CSF) in vitro. The pathogenesis of JMML involves disruption of GM-CSF signal transduction resulting from mutations of the components of the RAS signaling pathway, including NF1, PTPN11, NRAS, and KRAS. Somatic point mutations of the RAS genes at codons 12, 13, and 61 are found in approximately 20% of patients. Although most patients with JMML die due to progressive disease within 12 months unless treated with hematopoietic stem cell transplantation (HSCT), Matsuda et al reported that JMML patients with NRAS or KRAS glycine to serine substitution improved spontaneously. Other groups in Europe did not confirm this observation, and treatment for patients with JMML and RAS mutations is controversial. Therefore, in the present study, we analyze the association between the mutational status of RAS and prognoses of patients with JMML. Patients and Methods: Eighty children diagnosed with JMML between 1988 and 2010 were studied retrospectively. We performed a mutational analysis of NRAS, KRAS, PTPN11, and C-CBL genes. Results: Seventeen patients (21%) had RAS mutations [NRAS (n = 13) and KRAS (n = 4)], while PTPN11 and C-CBL mutations were found in 28 patients (35%) and 5 patients (6.3%), respectively (Four patients were included in the previous report; Matsuda et al, Blood, 2007). Five children had clinical evidence of NF1 mutations. Among NRAS mutations, G12D and G13D were the most common (n = 6 and n = 5, respectively). Only one patient carried a G12S substitution, which was reported as a favorable mutation. Three patients with KRAS mutations had G13D substitutions. Compared to patients with other mutations or without any aberrations, patients with RAS mutations were significantly younger at diagnosis (median age: 12 months vs. 24 months, p = 0.011), while other known predictive factors such as HbF level and platelet count were not significantly different at diagnosis (median HbF level: 9.1 % vs. 22.2 %, p = 0.295; median platelet count: 27.5 × 109/L vs. 49.0 × 109/L, p = 0.390). Monosomy 7 was observed in seven patients without RAS mutations, and all patients with RAS mutations had normal karyotypes. Among untransplanted patients with RAS mutations, three achieved long-term survival (20, 84, and 209 months after diagnosis). The probability of 5-year overall survival estimated by the Kaplan-Meier method was significantly higher for patients with RAS mutations than for those without (85.7% vs. 30.4%, p = 0.033). Conclusion: These results suggest that JMML patients with RAS mutations may be a distinct subgroup with favorable outcomes in spite of other than G12S. Disclosures: No relevant conflicts of interest to declare.

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C-Cbl but Not TET2 Mutations Are Present in Patients with Juvenile Myelomonocytic Leukemia.

Blood ◽

10.1182/blood.v114.22.420.420 ◽

2009 ◽

Vol 114 (22) ◽

pp. 420-420 ◽

Cited By ~ 1

Author(s):

Hideki Muramatsu ◽

Hideki Makishima ◽

Anna Malgorzata Jankowska ◽

Heather Cazzolli ◽

Christine O'Keefe ◽

...

Keyword(s):

Copy Number ◽

Significant Proportion ◽

High Density ◽

Juvenile Myelomonocytic Leukemia ◽

Kras Mutations ◽

Hemoglobin F ◽

Hematopoietic Stem ◽

Monosomy 7 ◽

Gm Csf ◽

Myelomonocytic Leukemia

Abstract Abstract 420 Juvenile myelomonocytic leukemia (JMML) is a distinct subtype of myelodysplastic syndrome/myeloproliferative disorder (MDS/MPD) which, in analogy to chronic myelomonocytic leukemia (CMML), is characterized by excessive proliferation of myelomonocytic cells, but unlike CMML it occurs in young children and shows characteristic hypersensitivity to granulocyte-macrophage colony-stimulating factor (GM-CSF). Chromosomal defect are present in 22% of patients in particular involving del7/7q. Mutations of genes involved in GM-CSF signal transduction, including RAS and PTPN11, can be identified in a majority of children with JMML, constitutional mutations of NF1 can be found in another 10% of patients with JMML, but in significant proportion of patients no molecular lesions were identified. To further clarify the molecular pathogenesis of JMML we have applied a high density SNP array-based karyptyping and screened for associated mutations including established defected in RAS, PTPN11 and NF1 but also c-Cbl and TET genes, recently identified in patients with CMML and MDS/MPD. We studied 49 children with JMML diagnosed between 1988 and 2008 in 28 institutions throughout Japan. The median age at diagnosis was 28 months (range, 1-75 months). Karyotypic abnormalities were detected in 11 patients, including 7 patients with monosomy 7. Two children had clinical evidence of NF1 mutations. Out of 49 patients, 32 received hematopoietic stem cell transplantation (HSCT). We performed mutational analysis of the genes known to be affected by mutations in JMML. PTPN11 mutations were found in 26/49 (53%) while NRAS and KRAS mutations were found in 2/49 (4%) and 1/49 (2%), respectively. None of the patients screened showed the presence of TET2 mutations, previously shown to be present in a significant proportion of patients with MDS/MPD, including CMML. High-density Affymetrix 250K single nucleotide polymorphism array (SNP-A) were applied as a karyotyping platform to identify LOH and submicroscopic copy number changes. Signal intensity was analyzed and SNP calls determined using Gene Chip Genotyping Analysis Software Version 4.0 (GTYPE). Copy number and areas of UPD were investigated using Hidden Markov Model and CNAG v3.0 software. Compared to the results of conventional metaphase cytogenetics (MC), SNP-A identified significantly more genetic abnormalities (25% vs 49%; p=.02). In 1 patient UPD17q was present ivolving NF1 locus. In 4 patients UPD11q involving c-cbl locus (11q23.1) was found. Sequencing of c-Cbl gene family revealed mutations of c-Cbl in 5/49 (10%), and no Cbl-b mutations. All but 1 mutations were homozygous and were located in the RFD (exon 8 and intron 8). C-Cbl mutations were mutually exclusive with PTPN11, NRAS, and KRAS mutations or had clinical diagnosis of NF1. Unlike in CMML, no UPD4q24 or homo- or heterozygous TET2 mutations were found. Histomorphologic analysis did not reveal any distinct c-Cbl mutation-associated features or differences in count between patients grouped based on the presence of specific mutations. Similarly, there were no differences in gender, or the presence of cytogenetic abnormalities and the probability of 2 year overall survival of c-Cbl mutant cases between patients grouped according to mutational status. All patients with c-Cbl mutations displayed GM-CSF hypersensitivity at initial presentation but did not differ in this feature from the remaining JMML patients. However, mutant c-Cbl cases showed earlier presentation (median age 12 months vs. 29 months, p = .037) and lower median hemoglobin F fraction (3.5 % vs. 25%, p=.02). In sum, c-Cbl mutations constitute a novel important pathogenic lesion in JMML. While their presence suggests functional similarity to CMML, absence of TET2 mutation in JMML and rarity of PTPN11 mutations in CMML constitute important distinctive features of both diseases. Disclosures: No relevant conflicts of interest to declare.

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Correlation of Clinical Features with the Mutational Status of GM-CSF Signaling Pathway-Related Genes in Children with Juvenile Myelomonocytic Leukemia

Blood ◽

10.1182/blood.v110.11.1528.1528 ◽

2007 ◽

Vol 110 (11) ◽

pp. 1528-1528 ◽

Cited By ~ 1

Author(s):

Nao Yoshida ◽

Hiroshi Yagasaki ◽

Ayami Yoshimi ◽

Yoshiyuki Takahashi ◽

Yinyan Xu ◽

...

Keyword(s):

Prognostic Factors ◽

Clinical Outcome ◽

Clinical Features ◽

Juvenile Myelomonocytic Leukemia ◽

Gm Csf ◽

Ptpn11 Mutation ◽

Mutational Status ◽

Hbf Level ◽

Mutation Age ◽

Myelomonocytic Leukemia

Abstract Juvenile myelomonocytic leukemia (JMML) is a rare clonal myeloproliferative disorder that affects young children. It is characterized by specific hypersensitivity to granulocyte-macrophage colony-stimulating factor (GM-CSF) in vitro. Mutations in RAS, NF1, or PTPN11 positioned in the GM-CSF signal pathway, are thought to be involved in the pathogenesis of JMML. However, no information is available on the relationship between these mutations and clinical features of JMML. The impacts of these mutations on clinical outcome also remain unclear. We tested 49 Japanese children with JMML for N-RAS, K-RAS, and PTPN11 mutations and evaluated their clinical significance. We also assessed correlations between mutational status and clinical and laboratory findings, including age at diagnosis, fetal hemoglobin (HbF), platelet count, and cytogenetic abnormality, all which have been proposed as prognostic factors for JMML. Of the 49 JMML patients, cytogenetic abnormalities were detected in 13, including 8 with monosomy 7. For 2 patients, a clinical diagnosis of neurofibromatosis type 1 (NF1) was confirmed. PTPN11 and N-/K-RAS mutations were found in 22 (45%) and 8 (16%) patients, respectively. Neither PTPN11 nor RAS mutations nor NF1 were present in 17 (35%) patients, and no simultaneous aberrations in these genes were found. In patients with the PTPN11 mutation, age at diagnosis was older (35 vs 11 months; P=0.001, or 12 months; P<0.01) and HbF level was higher (31 vs 10%; P=0.03, or 16%; P<0.01) than for patients with the RAS mutation or without any aberration, suggesting that the clinical outcome for patients with the PTPN11 mutation might be poorer, because a higher HbF level and older age have been reported to be poor prognostic factors. In fact, overall survival (OS) at 5 years was lower for patients with the PTPN11 mutation than for those without (20±9% vs 58±9%; P=0.02). In addition to PTPN11 mutation, age older than 24 months (P<0.01) and abnormal karyotype (P=0.02) were also associated with poor prognosis for OS. Of the 49 patients, 33 received stem cell transplantation (SCT). OS probabilities for patients with and without a mutation in PTPN11 at 5 years after SCT were 25±10% and 64±12%, respectively (P=0.04). More importantly, mutation in PTPN11 was the only unfavorable factor for relapse after SCT (P<0.01). Seven patients died owing to relapse and 12 from complications. All patients who died after relapse had a PTPN11 mutation. In summary, our results suggest that PTPN11-mutated JMML might be a distinct subgroup with specific clinical characteristics and a poor outcome.

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Somatic mosaicism for oncogenic NRAS mutations in juvenile myelomonocytic leukemia

Blood ◽

10.1182/blood-2012-02-406090 ◽

2012 ◽

Vol 120 (7) ◽

pp. 1485-1488 ◽

Cited By ~ 17

Author(s):

Sayoko Doisaki ◽

Hideki Muramatsu ◽

Akira Shimada ◽

Yoshiyuki Takahashi ◽

Makiko Mori-Ezaki ◽

...

Keyword(s):

Clinical Symptoms ◽

Somatic Mosaicism ◽

Juvenile Myelomonocytic Leukemia ◽

Hematopoietic Stem ◽

Gm Csf ◽

Mild Disease ◽

Myeloid Neoplasm ◽

Buccal Smear ◽

Spontaneous Improvement ◽

Myelomonocytic Leukemia

Abstract Juvenile myelomonocytic leukemia (JMML) is a rare pediatric myeloid neoplasm characterized by excessive proliferation of myelomonocytic cells. Somatic mutations in genes involved in GM-CSF signal transduction, such as NRAS, KRAS, PTPN11, NF1, and CBL, have been identified in more than 70% of children with JMML. In the present study, we report 2 patients with somatic mosaicism for oncogenic NRAS mutations (G12D and G12S) associated with the development of JMML. The mutated allele frequencies quantified by pyrosequencing were various and ranged from 3%-50% in BM and other somatic cells (ie, buccal smear cells, hair bulbs, or nails). Both patients experienced spontaneous improvement of clinical symptoms and leukocytosis due to JMML without hematopoietic stem cell transplantation. These patients are the first reported to have somatic mosaicism for oncogenic NRAS mutations. The clinical course of these patients suggests that NRAS mosaicism may be associated with a mild disease phenotype in JMML.

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How I treat juvenile myelomonocytic leukemia

Blood ◽

10.1182/blood-2014-08-550483 ◽

2015 ◽

Vol 125 (7) ◽

pp. 1083-1090 ◽

Cited By ~ 94

Author(s):

Franco Locatelli ◽

Charlotte M. Niemeyer

Keyword(s):

Disease Recurrence ◽

Mitogen Activated Protein Kinase ◽

Leukemic Cells ◽

Juvenile Myelomonocytic Leukemia ◽

Hematopoietic Stem ◽

Ras Mutations ◽

Mitogen Activated Protein ◽

Myelomonocytic Leukemia ◽

Kinase Pathway ◽

Excessive Proliferation

Abstract Juvenile myelomonocytic leukemia (JMML) is a unique, aggressive hematopoietic disorder of infancy/early childhood caused by excessive proliferation of cells of monocytic and granulocytic lineages. Approximately 90% of patients carry either somatic or germline mutations of PTPN-11, K-RAS, N-RAS, CBL, or NF1 in their leukemic cells. These genetic aberrations are largely mutually exclusive and activate the Ras/mitogen-activated protein kinase pathway. Allogeneic hematopoietic stem cell transplantation (HSCT) remains the therapy of choice for most patients with JMML, curing more than 50% of affected children. We recommend that this option be promptly offered to any child with PTPN-11-, K-RAS-, or NF1-mutated JMML and to the majority of those with N-RAS mutations. Because children with CBL mutations and few of those with N-RAS mutations may have spontaneous resolution of hematologic abnormalities, the decision to proceed to transplantation in these patients must be weighed carefully. Disease recurrence remains the main cause of treatment failure after HSCT. A second allograft is recommended if overt JMML relapse occurs after transplantation. Recently, azacytidine, a hypomethylating agent, was reported to induce hematologic/molecular remissions in some children with JMML, and its role in both reducing leukemia burden before HSCT and in nontransplant settings requires further studies.

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A Pediatric Case of Systemic Lupus Erythematosus Developed 10 Years after Cord Blood Transplantation for Juvenile Myelomonocytic Leukemia

Case Reports in Transplantation ◽

10.1155/2012/619126 ◽

2012 ◽

Vol 2012 ◽

pp. 1-4

Author(s):

Masayuki Nagasawa ◽

Yuki Aoki

Keyword(s):

Cord Blood ◽

Lupus Erythematosus ◽

Cord Blood Transplantation ◽

Juvenile Myelomonocytic Leukemia ◽

Systemic Lupus ◽

Hematopoietic Stem ◽

Monosomy 7 ◽

Blood Transplantation ◽

The Impact ◽

Myelomonocytic Leukemia

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is a most powerful immunotherapy for hematological malignancies. However, the impact of immunological disturbances as a result of allo-HSCT is not understood well. We experienced an 11-year-old boy who presented with systemic lupus erythemathosus (SLE) 10 years after unrelated cord blood transplantation of male origin for juvenile myelomonocytic leukemia (JMML) with monosomy 7. Bone marrow examination showed complete remission without monosomy 7. Genetic analysis of peripheral blood revealed mixed chimera with recipient cells consisting of <5% of T cells, 50–60% of B cells, 60–75% of NK cells, 70–80% of macrophages, and 50–60% of granulocytes. Significance of persistent mixed chimera as a cause of SLE is discussed.

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The JAK2 V617F Mutation Is Uncommon in Patients with Juvenile Myelomonocytic Leukemia.

Blood ◽

10.1182/blood.v106.11.4942.4942 ◽

2005 ◽

Vol 106 (11) ◽

pp. 4942-4942

Author(s):

Nao Yoshida ◽

Hiroshi Yagasaki ◽

Yinyan Xu ◽

Tomoko Yamamoto ◽

Kazuko Kudo ◽

...

Keyword(s):

Signal Transduction ◽

Mutational Analysis ◽

Jak2 V617f ◽

Jak2 V617f Mutation ◽

Juvenile Myelomonocytic Leukemia ◽

Ras Mutations ◽

Gm Csf ◽

V617f Mutation ◽

Signaling Components ◽

Myelomonocytic Leukemia

Abstract Juvenile myelomonocytic leukemia (JMML) is a rare, clonal myeloproliferative disorder afflicting young children and is characterized by specific hypersensitivity of JMML cells to GM-CSF in vitro. The pathogenesis of JMML seems to arise from dysregulation of GM-CSF signal transduction. Approximately, 75% of patients with JMML exhibit dysregulation due to mutations in RAS, NF1 or PTPN11, all of which are positioned in the GM-CSF pathway. Potential causative mutations in remaining patients are anticipated to be in signaling components downstream of the GM-CSF receptor. Recently, a somatic point mutation (JAK2 V617F) in the JAK2 gene, which plays a major role in the development of hematopoietic cells by transducing signals from growth factor receptors including GM-CSF receptor, was found commonly in polycythemia vera, essential thrombocythemia and idiopathic myelofibrosis. All these myeloproliferative disorders are also characterized by hypersensitivity of hematopoietic progenitor cells to several growth factors and cytokines. Because the frequency of JAK2 V617F mutation in JMML remains unknown, we performed mutational analysis of JAK2 in 39 Japanese children (aged 1 to 69 months) with JMML to assess the pathogenetic relevance of this mutation in JMML, in addition to mutational analysis of PTPN11 and N-RAS. Genomic DNA were prepared from bone marrow or peripheral blood samples taken at initial diagnosis. Mutations of JAK2 (exon 12), PTPN11 (exon 3 and 13) and N-RAS (exon 1 and 2) were screened by direct sequencing. PTPN11 or N-RAS mutations were found in 19 (49%) or 3 (8%) patients respectively, and this is compatible with previous reports. In this study, no JAK2 V617F mutations were detected in any of the 39 JMML patients. In conclusion, we confirmed the presence of PTPN11 and N-RAS mutations in JMML. However, the JAK2 V617F mutation appears to be uncommon in patients with JMML, while it is extraordinarily common in classic MPD. Future investigation should focus on other signaling components in the same signaling pathway as JAK2, or on other parallel signal transduction cascades of the GM-CSF receptor.

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Engraftment of NOD/SCIDγcnull Mice with Multilineage Neoplastic Cells from Patients with Juvenile Myelomonocytic Leukemia.

Blood ◽

10.1182/blood.v104.11.3422.3422 ◽

2004 ◽

Vol 104 (11) ◽

pp. 3422-3422

Author(s):

Tomoko Yamamoto ◽

Yoichi Nakamura ◽

Masafumi Ito ◽

Yinyan Xu ◽

Hiroshi Yagasaki ◽

...

Keyword(s):

Stem Cells ◽

T Cell ◽

T Lymphocyte ◽

B Lymphocyte ◽

Juvenile Myelomonocytic Leukemia ◽

Fish Analysis ◽

Hematopoietic Stem ◽

Monosomy 7 ◽

Murine Bone Marrow ◽

Myelomonocytic Leukemia

Abstract Jevenile myelomonocytic leukemia (JMML) is a rare myeloproferative disorder of early childhood, arising from pluripotent stem cells. Previous studies indicate the clonal nature of JMML, involving myeloid, erythroid, megakaryocyte and B-lymphoid lineage. However, it is unclear whether T lymphocyte lineage is involved or not. In one previous report, a patient with JMML and cytogenetic evidence of monosomy 7, a combination of fluorescence activated cell sorting and fluorescence in situ hybridization (FISH) analysis confirmed no T cell lineage involvement. One explanation of sparing T cell lymphocyte involvement in JMML is that the majority of T-lymphocytes are long-lived and borne before the occurrence of the disease. We demonstrated that cells from six patients of JMML repopurate in NOD/SCIDγcnull mice and differenciate into granulocyte, monocyte, erythroid, B-lymphocyte, T-lymphocyte and natural killer(NK) cells. The diagnosis of JMML was based on the internationally accepted criteria. 0.01 to 1×107mononuclear cells were injected through the tail vein of five week old NOD/SCIDγcnull mice. 12 week after transplantation mice were sacrificed and the cells are collected from the femoral bone and spleen and subjected to flow cytometry. The percentage of human CD45 antigen positive cells ranged from 41 to 73%. To examine the involvement of lymphocyte subpopulations, we purified human CD3+,CD19+and CD56+ cells from a murine bone marrow and spleen cells transplanted from a patient with monosomy 7. The purity of cells were more than 95%. The percentage of monosomy 7 cells determined by FISH analysis ranged from 96 to 100% in purified CD3+, CD19+and CD56+ cells. These findings support the concept that JMML originate in transplantable multilineage hematopoietic stem cells. This novel murine xenotransplant model should be useful to investigate the nature of stem cells and test new therapies for patients with JMML.

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Correlation of Clinical Features with Mutational Status in Children with Juvenile Myelomonocytic Leukemia.

Blood ◽

10.1182/blood.v108.11.2687.2687 ◽

2006 ◽

Vol 108 (11) ◽

pp. 2687-2687 ◽

Cited By ~ 1

Author(s):

Nao Yoshida ◽

Hiroshi Yagasaki ◽

Yinyan Xu ◽

Makito Tanaka ◽

Nobuhiro Nishio ◽

...

Keyword(s):

Prognostic Factors ◽

Cell Differentiation ◽

Clinical Features ◽

Novel Mutation ◽

Juvenile Myelomonocytic Leukemia ◽

Cytogenetic Abnormalities ◽

Ras Mutations ◽

Gm Csf ◽

Mutational Status ◽

Myelomonocytic Leukemia

Abstract Juvenile myelomonocytic leukemia (JMML) is a rare clonal myeloproliferative disorder that affects young children. It is characterized by specific hypersensitivity to granulocyte-macrophage colony-stimulating factor (GM-CSF) in vitro. Mutations in RAS, NF1, or PTPN11 positioned in the GM-CSF signal transduction pathway, which contribute to myeloid proliferation, have been recognized in the pathogenesis of JMML. Recently a multi-step model for leukemogenesis has been proposed. In this model, the pathogenesis of leukemia requires at least two classes of mutations:primary mutations of genes implicated in cell differentiation such as AML1 and PU.1 andadditional mutations of genes contributing to myeloid proliferation such as FLT3, RAS, and PTPN11. We hypothesized that in patients with JMML, in addition to known mutations of genes in the GM-CSF pathway involved in myeloid proliferation, potential causative mutations of other classes might be acquired. AML1 encodes a transcription factor that is essential for definitive hematopoiesis, and its mutations have recently been found in adults with acute myeloid leukemia and myelodysplastic syndrome. However, no information is available on the profiles of mutations in these genes and the relationship between these mutations and clinical features of JMML in children. We analyzed mutations of N-RAS, K-RAS, and PTPN11 in 50, and of AML1 in 30 Japanese children with JMML by direct sequencing. Correlation between the mutational status and clinical and laboratory findings, including age at diagnosis, sex, fetal hemoglobin (HbF), platelets count, cytogenetic abnormalities, and hepatomegaly, all which are suggested prognostic factors for JMML, were also assessed. Of the 50 patients with JMML, cytogenetic abnormalities were detected in 14, including 8 with monosomy 7. PTPN11 and N-/K-RAS mutations were found in 24 (48%) and 7 (14%) patients, respectively, and a novel mutation in AML1 was identified in one patient. No simultaneous mutations in these genes were found. Age at diagnosis was older (median 36 vs 11 months, p=0.0005) and HbF level was higher (31.0% vs 5.1%, p=0.033) in patients with the PTPN11 mutation than those with the RAS mutation. No difference was observed between patients with PTPN11 and RAS mutations in sex ratio, white blood cell count, platelets count, and the incidence of cytogenetic abnormalities and hepatomegaly. Our results suggest that the clinical outcome of patients with PTPN11 might differ from those with RAS mutations because a higher level of HbF and older age have been reported to be poor prognostic factors. In one patient with JMML, we identified a novel mutation in the AML1 gene that belongs to the class of genes contributing to cell differentiation instead of the class of genes in the GM-CSF pathway involved in myeloid proliferation.

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