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NPM1 mutation is the most common molecular abnormality in patients with acute myeloid leukemia (AML), especially normal karyotype AML (NK-AML), and is associated with a favorable prognosis in the absence of concomitant FLT3-ITD. Like other molecular abnormalities such as FLT3-ITD, C/EBPα and c-Kit mutation, NPM1 mutation normally presents as a recurrent molecular abnormality. The NPM1 mutation is generally used as a molecular marker in the prognosis evaluation of a patient with AML. Here, we report a different case. He was first diagnosed with NPM1 mutation-positive acute monocytic leukemia. However, he achieved no remission, but the NPM1 mutation dramatically became negative after induction chemotherapy. Finally, he achieved complete remission after salvage chemotherapy and the NPM1 mutation was still negative. To our knowledge, this is a rare case according to the worldwide published literature.

Recent studies have shown that Janus tyrosine kinase 2 (JAK2) V617F mutation is found in nearly all patients with polycythemia vera (PV) and underlie the basis of PV molecular pathogenesis. Moreover, JAK2 V617F patients with essential thrombocythemia (ET) have been found to have some clinical features similar to PV. To determine whether the same is true in a different Chinese patient population, we employed Allele-specific polymerase chain reaction in combination with sequence analysis to investigate the point mutation in a series of Chinese patients with hematological malignancies. A total of 99 Chinese myeloproliferative disorder patients and 120 additional patients with acute myeloid leukemia, acute lymphoblastic leukemia and myelodysplastic syndromes were studied. The V617F mutation was detected in genomic DNA of peripheral blood samples of 16 of 23 PV patients (69.6%), 21 of 45 ET patients (46.7%) and 3 of 8 patients with idiopathic myelofibrosis (37.5%). There were striking differences in clinical features such as hemoglobin, hematocrit and neutrophils percentages between V617F positive and negative patients with ET. Hence, our data support the idea that JAK2 V617F mutation divides ET patients into two subtypes, with the V617F positive group showing phenotypic similar to that of PV.

As JAK2 V617F, MPL W515L is a novel acquired mutation that induces constitutive cytokine-independent activation of the JAK-STAT pathway in myeloproliferative disorders (MPD). The discovery of this mutation provides a novel mechanism for activation of signal transduction in hematopoietic malignancies. To investigate its prevalence in Chinese patients with MPD, we introduced allele-specific PCR (AS-PCR) combined with sequence analysis to simultaneously screen MPL W515L and JAK2 V617F mutations in 190 MPD patients. MPL W515L mutation was found to be harbored in only one of 102 patients, who had essential thrombocythemia (ET, 1.0%) and was not detected in patients with polycythemia vera (PV), idiopathic myelofibrosis (IMF), and chronic myelogenous leukemia (CML). Sixty-eight BCR/ABL-negative MPD patients (46.3%) were found harboring JAK2 V617F mutation (PV, 62.5%; ET, 42.1%; IMF 38.1%). Furthermore, MPL W515L and JAK2 V617F mutations were not detected in patients of acute myeloid leukemia, acute lymphoblastic leukemia, myelodysplastic syndromes, and CML. It has been shown that MPL W515L mutations may contribute to the primary molecular pathogenesis of Chinese patients with ET.

Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening disorder occurring as a familial disease (FHL) or secondary to other diseases including infection (IAHS), rheumatologic disease (MAS),...