The Clinical Research About The Relationship Between JAK2,CALR,MPL Gene Mutation And BCR/ABL-Negative Myeloproliferative Neoplasms

Background:Myeloproliferative neoplasms (MPN) is a series of diseases derived from hematopoietic stem cell level, which is characterized by abnormal hematopoietic cell clonal expansion, function abnormalities, splenomegaly, thrombosis and bleeding tendency. Cell proliferation can also occur in the liver, spleen, lymph nodes and other extramedullary tissues. The pathogenesis of BCR-ABL-negative MPN (PV, ET, PMF) has not been fully elucidated. It is reported that about 90% of PV patients and 50% of the ET and PMF patients have JAK2V671F mutations. The mutation of guanine to cytosine, which is located in the JAK2 gene exon 14, makes valine to be replaced by phenylalanine, to allow the kinase activity of tyrosine phosphorylation. However, the correlation between JAK2V671F mutations and clinical manifestations is unclear.With further research, some new MPN associated mutations are found gradually, of which, MPL and CALR mutation are the two most studied types besides JAK2 gene. MPL plays an important role in the differentiation and proliferation of hematopoietic stem cells, which depends on JAK2 signaling to regulate erythropoietin receptor and MPL. Most of JAK2 and MPL double negative essential thrombocythemia and primary myelofibrosis patients hold the somatic mutations of calreticulin (CALR) gene exon 9. Calreticulin is multifunctional protein to ensure proper folding of newly synthesized glycoproteins, regulate the homeostasis of calcium and participate in multiple biological processes including proliferation, differentiation and apoptosis.Object:Statistically analyse the occurrence probability of PV, ET, PMF patients with JAK2, CALR, MPL mutations. Study the correlation between the JAK2V671F mutation and clinical manifestations such as, degree of bone marrow hyperplasia, thrombosis incidence, white blood cell count, hemoglobin level, platelet count.Methods:1. Sample:171 PV, ET, PMF cases diagnosed in Shandong Provincial Hospital, Department of Hematology during 2011 to 2016. The diagnostic criteria is based on 2008 WHO established criteria.2. Statistically analyse the mutation occurrence probability of these cases with JAK2V617F, JAK2 exon 12, MPL exon 10 and CALR exon 9.3. Divide PV, ET, PMF patients into two groups respectively:JAK2V671F mutation positive and negative groups.4. Statistical indicators:(1) General information:age, gender(2) laboratory tests:white blood cell count, hemoglobin level, platelet count, LDH,, degree of bone marrow hyperplasia, with or without bone marrow fibrosis(3) Clinical manifestations:with or without vein thrombosis, skin and mucous membranes and other parts of the digestive tract bleeding, fever, fatigue, night sweats, weight loss, hypersplenotrophy.5. Statistical Methods:Use SPSS 23.0 for statistical analysis, count data were compared using the t test, measurement data using the chi-square test, P<0.05 was considered statistically significant.Result:1. In this group of cases, JAK2V617 mutation positive rate of PV patients is 92.3%, JAK2V617 mutation positive rate of PV patients was 61.6%, JAK2V617 mutation positive rate of PV patients is 60.0%.129 of total 171 patients have JAK2V617 mutation, the positive rate was 75.4%.2. The incidence of MPL exon 10 mutations is lower, and the positive rate was 0 in PV patients,4%in ET patients, and 11% in PMF patients. CALR exon 9 mutation is not detected in PV patients. CALR exon 9 L367fs * 46 mutation is detected in 11 ET patients, and all occurre in JAK2V617F negative patients, CALR mutation positive rate of PMF patients was 22%.3. In the PV patients, age, gender, hemoglobin, and hematocrit difference basophils was not statistically significant between JAK2V617F mutation positive and negative groups, while white blood cell count, platelet count, and serum LDH level difference was statistically significant, P<0.05. There is no difference in thrombotic risk, the degree of bone marrow hyperplasia and bone marrow fibrosis between positive and negative groups.4. In the ET patients, gender, hemoglobin, hematocrit difference was not statistically significant between the two groups, while white blood cell count, platelet count, basophils, eosinophils count was statistically significant, P<0.05. There is no difference in the degree of bone marrow hyperplasia, splenomegaly and thromboembolic events incidence between positive and negative groups.5. In the PMF patients, JAK2V617F mutation positive group had higher white blood cell count. There is no significant differences in other clinical characteristics such as age, gender, hemoglobin, platelet count, bone marrow fibrosis, spleen size, lymph node.Conclusion:1.The incidences of different types mutations in PV, ET and PMF patients are significantly different. JAK2V617F mutation rate is much higher in PV patients than that in ET or PMF. MPL exon 10 mutation rate is low, mainly in the ET and PMF patients. CALR gene mutation is mainly detected in JAK2V617F(-) ET and PMF patients.2. There is a certain correlation between JAK2V617F mutation and the clinical characteristics of MPN patients. In PV patients, mutation positive patients have a higher peripheral WBC, PLT count and serum LDH levels. Mutation-positive ET patients have lower peripheral blood PLT count. In PMF patients, the mutation positive group had higher white blood cell count.