OBJECTIVE

To characterize the molecular profile in patients with Ph negative myeloproliferative neoplasms (MPN) by exploring 49 gene mutations.

METHODS

Targeted gene sequencing were performed to analyze 49 MPN-associated genes in 51 patients with Ph negative MPN, of which CARL (exon 9), NPM1 (exon 12) and CEBPA (TAD, BZIP domains) were investigated by using Sanger sequencing simultaneously, while FLT3-ITD was assessed by PCR method.

RESULTS

Mutations were detected in 73.5% (36/49) of genes, and the mutational rates of JAK2-V617F, CALR (exon 9) and MPL were 60.8%(31/51), 7.8%(4/51) and 7.8%(4/51) respectively, whereas the mutational rates of ASXL1, SETBP1, and SF3B1 were around 10%. In addition, 96.1% (49/51) of patients harbored at least one mutation, and more than half of the patients (52.9%, 27/51) possessed 3 or 4 gene mutations. The amount of gene mutations was significantly higher in patients with JAK2-V617F mutation than those without JAK2-V617F or CALR (exon 9) mutation (P<0.05). The last finding was that there was no statistically significant difference in the amount of mutations among four MPN subtypes (PV, ET, PMF, and MPN-U).

CONCLUSIONS

Most patients with Ph negative MPN possesses three or more gene mutations, with various mutational profiles.

Essential thrombocythemia(ET) is one of the Ph chromosome-negative myeloproliferative neoplasms. Some studies discovered that the mutation of JAK2 V617F existed in 50%-70% patients with ET. Recently, many significant advances in researches about pathogenesis of ET, such as mutations of JAK2V617F, MPL, CALR and other related mutation; the epigenetic abnomalities in incidence of ET; the changes of bone marrow microenvironment of ET and the regulation of related cytokines were obtained. In this article, the advances of above mentioned aspects of ET are summarized.

OBJECTIVE

To investigate changes of protein expression profiles between human choriocarcinoma JeG-3 cell line and its floxuridine (FUDR)-resistant sub-line.

METHODS

The differentially expressed proteins were identified by using two dimension difference gel electrophoresis (2-DE) and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) approaches. Gene ontology (GO) analysis and Pathway analysis were used to screen the candidate proteins. The levels of the proteins in chemo-resistant sub-lines were validated by western blot. Ribonucleic acid interference (RNAi) was used to knockdown the expression of calreticulin (CALR) and (or) protein disulfide-isomerase A3 (PDIA3) respectively.

RESULTS

Forty-six proteins spots were found to be significantly different in spot intensity by statistical analysis between chemo-resistance sub-line and parent cell line, of which 31 proteins were identified by MALDI-TOF-MS. Comparing to the parent cell lines, three endoplasmic reticulum (ER) protein folding molecular chaperones: CALR, PDIA3 and 78 000 glucose-regulated protein (GRP78) screened out were increased significantly in floxuridine-resistant sub-line and were verified by western blot. The resistance index decreased by knockdown the CALR and/or PDIA3 expression in FUDR-resistant sub-line 76.3% (36.7 ± 2.0 vs. 8.7 ± 3.1, P < 0.05) and 51.4% (36.7 ± 2.0 vs. 17.8 ± 1.2, P < 0.05) respectively.

CONCLUSIONS

These ER protein folding molecular chaperones, CALR, PDIA3 and GRP78, may involved in the mechanism of FUDR-resistance choriocarcinoma.

The aim of this study was to analyze the mutation rate of JAK2V617F, MPLW515L/K and CALR genes in adult patients with essential thrombocythemia (ET) and the accuracy of the combined detection by the receiver operating curve. Three hundred and forty-two cases with high-platelets (≥300×109/l) were consecutively selected. The patients were analyzed for routine blood examination, bone marrow biopsy and genetic testing. One hundred and fifty-four cases (45.03%) were diagnosed with ET and 188 cases of secondary thrombocythemia according to the hematopoietic and lymphoid tissue tumor classification standards of 2008. It was found that the mutant type of three genes showed three bands, whereas only one band for wild-type. The JAK2V617F and MPL mutations did not cause a change in the open reading frame and the CALR mutation resulted in its change. The mutation rate of JAK2V617F and CALR in ET group was significantly higher than that in the secondary thrombocythemia group (p<0.05). The positive mutation rate of MPL was only 4.55%. JAK2V617F-positive mutation alone was used to diagnose with ET. The area under the curve (AUC) was 0.721. The sensitivity was 72.4%, the specificity was 79.5% and the cut-off value was 0.25. When CALR-positive mutation alone was used to diagnose ET, the AUC, sensitivity, specificity and cut-off value were 0.664, 68.4, 82.4 and 0.09%, respectively. JAK2V617F combined with CALR mutation were used for diagnosis of ET. The AUC was 0.862, the sensitivity was 85.9%, the specificity was 87.8%, and the cut-off values were 0.21 and 0.07. In conclusion, the positive mutation rate of JAK2V617F and CALR in ET was higher, and the sensitivity, specificity and accuracy of the diagnosis of ET were significantly improved using the detection of JAK2V617F and CALR.

The olfactory bulb (OB) is rich in the number and variety of neurotransmitter and neuropeptide containing cells, in particular in the glomerular layer. Several reports suggest that numbers of some periglomerular phenotypes could change depending on age. However, it is unclear whether the different classes of periglomerular interneurons are modified or are maintained stable throughout life. Thus, our first objective was to obtain the absolute number of cells belonging to the different periglomerular phenotypes at adulthood. On the other hand, the olfactory bulb is continously supplied with newly generated periglomerular neurons produced by stem cells located in the subventricular zone (SVZ) and rostral migratory stream. Previously, we demonstrated that the implantation of a physical barrier completely prevents SVZ neuroblast migration towards the OB. Then, another objective of this study was to evaluate whether stopping the continuous supply of SVZ neuroblasts modified the different periglomerular populations throughout time. In summary, we estimated the total number of TH-IR, CalB-IR, CalR-IR and GAD-IR cells in the OB glomerular layer at several time points in control and barrier implanted adult rats. In addition, we estimated the volume of glomerular, granular and complete OB. Our main finding was that the number of the four main periglomerular populations is age-dependent, even after impairment of subventricular neuroblast migration. Furthermore, we established that these changes do not correlate with changes in the volume of glomerular layer.

Calreticulin (CALR) mutations are detected in the majority of JAK2 wild type patients with essential thrombocythemia (ET). Unlike JAK2^V617F and MPL point mutations, CALR mutations are highly heterogeneous, with several types of indels being reported so far. CAL2 is a monoclonal antibody specifically recognizing the C-neoterminal peptide derived from all the frameshift mutations of CALR. We retrospectively analysed 172 ET patients diagnosed at our Institution from 1980 to 2015. In JAK2^V617F- and MPL^W515K/L-wild type patients CALR mutations were searched on peripheral blood and CAL2 immunostaining was performed on bone marrow. In addition, bone marrow biopsies were histologically reviewed for megakaryocytic features. Thirty-one patients (18%) were CALR-mutated. Concordance between molecular and immunohistological detection of CALR mutations was near complete, albeit a single patient was found to be positive by molecular tests only. Two patterns were defined in CAL2-positive bone marrow samples, characterized by staining of almost only megakaryocytes (pattern A: 41%) or staining of megakaryocytes and ≥ 2% small non megakaryocytic elements (pattern B: 59%), at least partially being myeloid precursors. Pattern B biopsies had higher cellularity and number of megakaryocytes compared to pattern A samples. In this series, CAL2 allowed rapid and cost-efficient identification of CALR-mutated ET patients. The biological significance of different staining pattern should be confirmed in wider and independent series.

Mutations in JAK2, MPL, or CALR are detected in more than 80% of myeloproliferative neoplasm (MPN) patients and are thought to play a driver role in MPN pathogenesis via autosomal activation of the JAK-STAT signaling cascade. Mutant CALR binds to MPL, activates downstream MPL signaling cascades, and induces essential thrombocythemia in mice. However, embryonic lethality of Calr-deficient mice precludes determination of a role for CALR in hematopoiesis. To clarify the role of CALR in normal hematopoiesis and MPN pathogenesis, we generated hematopoietic cell-specific Calr-deficient mice. CALR deficiency had little effect on the leukocyte count, hemoglobin levels, or platelet count in peripheral blood. However, Calr-deficient mice showed some hematopoietic properties of MPN, including decreased erythropoiesis and increased myeloid progenitor cells in the bone marrow, and extramedullary hematopoiesis in the spleen. Transplantation experiments revealed that Calr haploinsufficiency promoted the self-renewal capacity of hematopoietic stem cells. We generated CALRdel52 mutant transgenic mice with Calr haploinsufficiency as a model that mimics human MPN patients and found that Calr haploinsufficiency restored the self-renewal capacity of hematopoietic stem cells damaged by CALR mutations. Only recipient mice transplanted with Lineage－Sca1+c-kit+ cells harboring both CALR mutation and Calr haploinsufficiency developed MPN in competitive conditions, showing that CALR haploinsufficiency was required for the onset of CALR-mutated MPNs.

Buccal epithelial cells harbor an MPN-associated CALR mutation in a patient with CALR-mutant essential thrombocytosis, Ph+ CML, and no germ line CALR mutation.

Introduction: The pathogenesis of myeloproliferative neoplasms (MPNs) is closely related to the acquisition of specific molecular alterations in JAK2, MPL, or CALR genes, the presence of which represent major diagnostic criteria in the WHO classification. The CALR exon 9 insertions and deletions are very heterogeneous, and their detection mainly relies on polymerase chain reaction (PCR) fragment length analysis.

Methods: We report on the rare nonclassical profiles that we observed among the 1382 patients analyzed by PCR fragment length analysis. In difficult cases, we tested germline DNA and performed NGS analysis.

Results: We faced some troubling results because of the presence of several unexpected peaks. Our investigations showed that they resulted from a mix of isolated or double somatic mutations combined with germline alterations which could be misleading for a correct diagnosis. The precise interpretation of such difficult cases is mandatory as a misinterpretation could lead to the prescription of cytoreductive drugs to nondiseased persons or to an absence of treatment in true MPN patients.

Conclusion: Our observations showed that every mutation should be verified by direct Sanger sequencing, and we show that sometimes it may be necessary to study germline DNA and to complement with NGS analysis to precisely interpret the molecular alterations.

Keywords: CALR; calreticulin; diagnosis; myeloproliferative neoplasms.

The 2016 WHO-CMP classification proposal defines a broad spectrum of JAK2 V617F mutated MPN phenotypes: normocellular ET, hypercellular ET due to increased erythropoiesis (prodromal PV), hypercellular ET with megakaryocytic-granulocytic myeloproliferation and splenomegaly (EMGM or masked PV), erythrocythemic PV, early and overt classical PV, advanced PV with MF and post-PV MF. ET heterozygous for the JAK2 V617F mutation is associated with low JAK2 mutation load and normal life expectance. PV patients are hetero-homozygous versus homozygous for the JAK2 V617F mutation in their early versus advanced stages with increasing JAK2 mutation load from less than 50% to 100% and increase of MPN disease burden during life long follow-up in terms of symptomatic splenomegaly, constitutional symptoms, bone marrow hypercellularity and secondary MF. Pretreatment bone marrow biopsy in prefibrotic MPNs is of diagnostic and prognostic importance. JAK2 exon 12 mutated MPN is a distinct benign early stage PV. CALR mutated hypercellular thrombocythemia show distinct PMGM bone marrow characteristics of clustered larged immature dysmorphic megakaryocytes with bulky (bulbous) hyperchromatic nuclei, which are not seen in JAK2 mutated ET and PV. MPL mutated normocellular thrombocythemia is featured by clustered giant megakaryocytes with hyperlobulated stag-horn-like nuclei without features of PV in blood and bone marrow. Myeloproliferative disease burden in each of the JAK2, CALR and MPL MPNs is best reflected by the degree of anemia, splenomegaly, mutation allele burden, bone marrow cellularity and myelofibrosis.

Objective: To investigate the clinical characteristics of essential thrombocytopenia (ET) patients with positive mutations including JAK2, CALR, MPL, or negative mutations.

Methods: A total of 66 newly diagnosed ET cases from January 2016 to December 2018 in Department of Hematology, Huaian No.1 People's Hospital affiliated to Nanjing Medical University were analyzed. Statistical analysis data included the patient's sex, age, symptoms, thrombosis and embolism events, spleen omegaly, platelet count (Plt), leukocyte (WBC) count, hemoglobin (Hb), fibrinogen (FIB), thrombus elastic diagram (TEG), serum potassium, blood glucose (GLU), lactate dehydrogenase (LDH), JAK2, CALR and MPL mutations, treatment options, and efficacy.

Results: All the patients were not MPL-positive, and divided in three groups: JAK2 mutation (46 cases, 69.7%), CALR mutation (9 cases, 13.6%) and gene negative mutation (11 cases, 16.7%) group. The average age of patients in the JAK2 mutation group was 63.2 years old, and significantly higher than that in the CALR mutation group (51.8 year) and gene negative group (50.2 year) (P＜0.05). Compared with the JAK2 mutation group and gene negative group, the CALR mutation group had lower WBC count (6.3×10⁹/L vs 13.79×10⁹/L) (P=0.003) (6.3×10⁹/L vs 9.70×10⁹/L) (P=0.009). Also the Hb level of patients in CALR mutation group was lower than the JAK2 mutation group (121.22 g/L vs 136.2 g/L) (P=0.036). However, there was higher tumor burden in the CALR mutation group, compared with the gene negative mutation group (300.11 U/L vs 227.4 U/L) (P=0. 033). There was no significant difference among the three groups, such as the Plt counts, serum potassium level, GLU level and FIB level (P＞0.05). In addition, thrombus and embolism appeared in 30.3% (20/66) cases. 18.2% (12/66) cases were complicated with hyperkalemia, which significantly correlated with Plt counts (r=0.518). TEG was performed in 34 patients, of which 41.2% (14/34) had abnormal TEG and 55.9% (19/34) were accompanied by Plt count ＞ 1 000 ×10⁹/L, but there was no significant correlation between them (r=0.134). After routine clinical treatment, all the 66 cases achieved partial or complete hematological remission, but the disease usually repeated. Until now 4.5% (3/66) cases had been converted to myelofibrosis (MF) all with JAK2 mutation, but without advancing to acute myeloid leukemia.

Conclusion: ET patients with JAK2 mutation have higher incidence, moreover were in older age. However, the patients with CALR mutations display lower WBC count and Hb level, but higher tumor burden. In short, the multiple gene mutations of ET showed different clinical features closely relates with the prognosis, thus providing guidance for the clinical diagnosis and treatment.

题目: 原发性血小板增多症66例临床分析.

目的: 探讨原发性血小板增多症（ET）JAK2、CALR、MPL基因突变及阴性突变患者的临床特点.

方法: 选取2016年01月至2018年12月在南京医科大学附属淮安第一医院血液科住院确诊的66例ET患者，录入患者的性别、年龄、临床症状、有无血栓事件、脾大、血小板数（Plt）、白细胞数（WBC）、血红蛋白（Hb）、纤维蛋白原（FIB）、血栓弹力图（TEG）、血钾、血糖（GLU）、乳酸脱氢酶（LDH）以及JAK2、CALR 和 MPL基因突变，治疗方案及疗效。对以上数据进行统计分析.

结果: 所有患者MPL突变阴性，故根据基因突变分为3组，JAK2突变组（46例，69.7%）、CALR 突变组（9 例，13.6%）和基因阴性组（11例，16.7%）。JAK2突变组患者的平均发病年龄为63.2岁，与CALR突变组（51.8岁）和基因阴性组（50.2岁）相比，具有显著的统计学差异（P＜0.05）。CALR突变组与JAK2突变组、基因阴性组相对比，WBC数低（6.3×10⁹/L vs 13.79×10⁹/L， P=0.003；6.3×10⁹/L vs 9.70×10⁹/L，P=0.009）；Hb水平较JAK2突变组低（121.22 g/L vs 136.2 g/L，P=0.036）； 但CALR突变组的肿瘤负荷较基因阴性组高（300.11 U/L vs 227.4 U/L，P=0.033）；3组之间的Plt数、血钾水平、GLU及FIB水平无统计学差异（P＞0.05）。另外，30.3%（20/66）患者存在血栓及栓塞事件，18.2%（12/66）患者合并高钾血症，且高钾血症与Plt数具有显著的相关性（r=0.518）。34例患者给予TEG检查，其中41.2%（14/34）患者出现TEG异常，55.9%（19/34）同时伴有Plt数＞1000×10⁹/L，但2者之间无显著的相关性（r=0.134）。66例患者采用常规临床治疗方案后均达部分或完全血液学缓解，但有疾病反复，4.5%（3/66）进展为骨髓纤维化（MF），均为具有JAK2突变患者。暂无进展为急性髓系白血病的病例.

结论: 伴有JAK2突变的ET患者发病率更高、且年龄偏大，然而CALR突变阳性患者具有更低的WBC数与Hb水平，却具更高的肿瘤负荷。总之，ET患者多样化的基因突变类型具有不同的临床特征，且与患者预后密切相关，这为临床诊疗工作提供了一定的思路.

Objective: To investigate the difference of clinical characteristics between young patients(age≤40 years old) and middle-older patients(age>40 years old) with the myeloproliferative neoplasms（MPN）.

Methods: The clinical data (gene mutations， peripheral blood routine examinations， imaging examination and past history) of 269 MPN patients was collected and analyzed.

Results: In essential thrombocythemia (ET) group, the proportion of triple-negative type in young patients was higher than that in middle-older group, while the peripheral white blood cell（WBC） and platelets（PLT） counts in the first visit were lower. In polycythemia vera (PV) group, the total detection rate of JAK2V617F (80.65%) was lower than that of other research reports. Young patients with PV showed the lower JAK2V617F rate and lower WBC count, compared with the middle-older aged patients. Both CALR and MPL mutations were not found in PV patients. There was only 1 primary myelofibrosis (PMF) patient aged <40 years old. 91.67% of the patients merged splenomegaly and this rate was higher than that of ET or PV patients. It was found that there were a diagnosed familial MPN family and an undiagnosed family， and the youngest patient was only 8 years old. The second-generation gene sequencing detection for them was not carried out.

Conclusion: Age is an important reference index in the assessment of risks. The MPN patients with different age and types show much difference in gene mutations, peripheral blood cell counts, thrombotic events and sizes of spleen. The onset ages of patients with familial MPN trends to be generational younger.

题目: 年龄分层下269例Ph染色体阴性骨髓增殖性肿瘤患者临床分析.

目的: 探讨按年龄分层的青年组（年龄≤40岁）与中老年组（年龄＞40岁）慢性骨髓增殖性肿瘤（MPN）患者临床特点的差异.

方法: 收集269例于本院就诊的MPN患者的临床资料，包括基因突变情况、初诊时外周血常规、影像学检查、既往病史等.

结果: 在原发性血小板增多症（ET）中，青年组患者三阴性比例高于中老年组患者，且青年组患者初诊时白细胞（WBC）和血小板（PLT）计数相对更低。在真性红细胞增多症（PV）患者中，JAK2V617F表达阳性率（80.65%）总体较国内外其他研究报道偏低。青年组PV患者JAK2V617F阳性率低于中老年组，且初诊时外周血WBC计数低于中老年组。所有PV患者中均未检测到CALR及MPL基因突变。在原发性骨髓纤维化（PMF）患者中，仅1例发病年龄<40岁；91.67%的患者表现有脾脏肿大，比例高于ET和PV患者。随访发现1个确诊家族性MPN家系和1个疑似家族性MPN家系，其中年龄最小的患者仅8岁，目前尚未对其进行二代基因测序检查，处于动态随访中.

结论: 年龄是MPN患者危险分层的重要参考指标。不同年龄和类型的MPN患者在基因突变、初诊时外周血细胞计数、罹患血栓事件、脾脏肿大等方面均存在差异。家族性MPN患者存在发病年龄逐代年轻化趋势.

Myeloproliferative neoplasms (MPNs) arise from hematopoietic stem cells (HSCs) with genetic abnormalities in combination with mutations in JAK2, MPL or CALR, which induce autosomal JAK-STAT pathway activation, and mutations in epigenetic regulator genes such as TET2 or DNMT3A. The prognosis of patients with polycythemia vera (PV) or essential thrombocythemia (ET) is relatively good, and the therapeutic goal in cases with PV or ET is to prevent thrombohemorrhagic complications. PV or ET patients at least 60 years of age or with a history of thrombosis are in a high-risk category, and are managed with low dose aspirin and cytoreductive therapy. Phlebotomy to maintain Ht<0.45 is also used to manage PV patients. The median survival for Japanese primary myelofibrosis (MF) patients is 3.9 years. Several factors including age>65 years, Hb<10 g/dl, the presence of constitutional symptoms, and the presence of blasts in blood were identified as being associated with shorter survival in MF patients. Those patients in the high-risk category are candidates for allogenic HSC transplantation (allo-HSCT), which is potentially curative but is also associated with higher therapy-related mortality. High-risk MF patients without indications for allo-HSCT are treated with JAK inhibitors, which can markedly ameliorate constitutional symptoms and splenomegaly, and might thereby lead to a degree of improvement in survival.

Polycythemia vera (PV) is a Philadelphia chromosome-negative chronic myeloproliferative neoplasm that is associated with a Janus kinase 2 (JAK2) mutation in most cases. The most recent update to the World Health Organization diagnostic criteria for PV was published in 2016. These were the modifications with the greatest effect: (1) lowering the hemoglobin threshold, allowing a diagnosis of PV at 16.5 g/dL in males and at 16.0 g/dL in females and (2) introducing a hematocrit cutoff (49% in males and 48% in females). Patients with PV who are older than 60 years or have had a previous thrombotic event are considered at high risk for thrombosis. Leukocytosis and a high allele burden are additional risk factors for thrombosis and myelofibrosis, respectively. After disease has progressed to post-polycythemia vera myelofibrosis (PPV-MF), survival must be assessed according to the recently developed Myelofibrosis Secondary to PV and ET-Prognostic Model (MYSEC-PM). This model is based on age at diagnosis, a hemoglobin level below 11 g/dL, a platelet count lower than 150 × 109/L, a percentage of circulating blasts of 3% or higher, a CALR-unmutated genotype, and the presence of constitutional symptoms. Therapy is based on phlebotomy to maintain the hematocrit below 45% and (if not contraindicated) aspirin. When a cytoreductive drug is necessary, hydroxyurea or interferon can be used as first-line therapy, although the demonstration of an advantage of interferon over hydroxyurea is still pending. In patients whose disease fails to respond to hydroxyurea, ruxolitinib is a safe and effective choice.

OBJECTIVE

The DNA-binding domain of ToxR protein of Vibrio parahaemolyticus was expressed using the Escherichia coli BL21lambdaDE3 protein expression system, and its DNA-binding activity was characterized.

METHODS

The fragment of DNA-binding domain at N-terminal of ToxR (ToxR-N) was amplified by PCR from V. parahaemolyticus strain RIMD2210633, and then cloned into the BamHI and Hind III sites of the vector pET28a. The recombinant plasmid pET28a was transformed into BL21lambdaDE3. Over-expression of His-ToxR-N in the LB medium was induced by adding 1 mmol/L IPTG (isopropyl-b-D-thiogalactoside). The over-expressed protein was purified under native conditions with nickel loaded HiTrap Chelating Sepharose columns (Amersham), and then the His-tag was removed by using restricted thrombin. The electrophoretic mobility shift assay was used to analyze the DNA-binding activity of ToxR-N to the promoter-proximal DNA regions of calR and VP1687, respectively. The promoter-proximal regions of calR and VP1687 were separately cloned into the pHRP309 vector containing a promoterless lacZ gene. Then, each of the two recombinant LacZ reporter plasmids was transformed into the wide-type strain (WT) and the toxR null mutant strain (DeltatoxR), respectively, to measure the promoter activity (the beta-Galactosidase activity) of the target genes in WT and DeltatoxR by using the beta-Galactosidase Enzyme Assay System.

RESULTS

The purified ToxR-N protein had the ability to bind to the upstream DNA regions of calR but not VP1687. The LacZ fusion results showed that the transcription of calR and VP1687 was positively and negatively regulated by ToxR in V. parahaemolyticus, respectively.

CONCLUSIONS

The recombinant ToxR-N protein could be used for studying the transcriptional regulation mechanism in V. parahaemolyticus. ToxR fulfills a mechanism of negative regulation of T3SS1 genes by activating the expression of calR through protein-proximal promoter DNA association.

Essential thrombocythemia (ET) is characterized by thrombotic and hemorrhagic events. The association of clinical characteristics of Chinese ET patients and additional sex combs like 1 (ASXL1) mutations in these patients has remained to be elucidated. In the present study, 72 newly diagnosed Chinese ET patients were enrolled to determine ASXL1 mutations. Mutations in ASXL1, Janus kinase (JAK)2, calreticulin (CALR) and myeloproliferative leukemia (MPL) genes were detected using Sanger sequencing, and data were statistically analyzed. The frequencies of ASXL1, JAK2 V617F, CALR and MPL W515 mutations in ET patients were 19.4% (14/72), 29.2% (21/72), 31.9% (23/72) and 0% (0/72), respectively. Of note, 28 ET patients (38.9%) were negative for JAK2, CALR and MPL mutations; these patients were classified as triple-negative (TN). The frequency of ASXL1 mutations in patients with JAK2 V617F, CALR and TN mutations was 23.8% (5/21), 21.7% (5/23) and 14.3% (4/28), respectively. ASXL1-mutant patients exhibited significant propensities for thrombotic events compared with the ASXL1 wild-type (wt) cohort (42.9 vs. 12.1%; P=0.021). In addition, JAK2 V617F-mutant patients had a higher mean age compared with CALR-mutant (64.76 vs. 52.96 years; P=0.008) or TN patients (64.76 vs. 51.14 years; P=0.002). Furthermore, more white blood cells in the peripheral blood (PB) were observed in JAK2 V617F-mutant patients compared with those in TN patients (12.40 vs. 8.20×109/l; P=0.02). In addition, CALR-mutant patients exhibited more platelets (PLT) in PB than JAK2 V617F-mutant patients (787.91 vs. 562.17×109/l; P=0.047). TN patients had a significantly lower incidence of clinical symptoms, including dizziness, palpitation and chest congestion compared with CALR- or JAK2 V617F-mutant patients (14.1 vs. 39.1%; P=0.043 and 14.1 vs. 38.1%; P=0.050). No significant difference in progression-free survival was observed between ASXL1-mutant and ASXL1-wt patients (P=0.590). In conclusion, ASXL1-mutant ET patients are prone to experiencing thrombotic events. There was no significant difference in the occurrence of thrombotic events among CARL-mutant, JAK2 V617F-mutant and TN patients. Furthermore, ASXL1-mutant/TN patients exhibited a higher number of PLT than ASXL1/JAK2 V617F-double mutant patients. Therefore, ASXL1 mutations may be a risk factor for the occurrence of thrombotic events in ET patients.

Representative diseases of BCR/ABL-negative myeloproliferative neoplasms (MPN) are polycythemia vera (PV), essential thrombocytosis (ET), and primary myelofibrosis (PMF). It was reported in 2005 that there is a common genetic mutation in Exon 14 of the JAK2 gene in MPN cases. The gene mutation is a point mutation at which the 617th amino acid of the JAK2 protein is substituted from valine to phenylalanine and is referred to as the JAK2 V617F mutation. Subsequently, JAK2 Exon 12 mutation, MPL gene mutation, and CALR gene mutation were detected in 2013, and it was revealed that in almost all cases of BCR/ABL- negative MPN, any gene mutation could be involved as a driver gene mutation. As a result, in the WHO classification 2016, gene mutation analyses of JAK2, MPL, and CALR were incorporated into the diagnostic criteria. Analysis of gene mutation is indispensable for the diagnosis of MPN. Also, its importance as an inspection item is increasing. [Review].

Objective: To analyze the gene mutation spectrum, clinical features, and the factors of disease progression and prognosis in patients with essential thrombocytosis (ET) . Methods: A retrospective analysis was conducted on 178 newly diagnosed ET patients admitted from February 1st, 2009 to November 1st, 2018. Results: Of the 178 patients, 89 were male and 89 female, and the median diagnosis age was 49.5 (3-86) years old. JAK2V617F, CALR and MPL mutations frequencies were 16.45% (1.67%-43.90%) , 40.00% (10.00%-49.15%) and 25.10% (25.00%-40.00%) , respectively. Compared with patients with CALR mutations, patients with JAK2V617F mutation had higher diagnosis age (P=0.035) , higher white blood cell count (P=0.040) , higher hemoglobin concentration (P=0.001) , and lower platelet count (P=0.002) , respectively. Of them, 47 patients (27.01%) developed thrombotic events before diagnosis, and 3 ones (1.72%) experienced thrombotic events after diagnosis. Multivariate analysis revealed age >60 years (P=0.013, OR=4.595, 95%CI 1.382-15.282) and cardiovascular risk factors (CVF) (P<0.001, OR=8.873, 95%CI 2.921-26.955) as risk factors for thrombotic events, CALR mutation (P=0.032, OR=0.126, 95%CI 0.019-0.838) as a protective factor for thrombotic events. Age >60 years (P=0.042, OR=4.045, 95%CI 1.053-15.534) was found to be a risk factor for the overall survival (OS) of ET patients. OS of age ≤60 years and age>60 years were calculated by Kaplan-Meier analysis to be (115.231±1.899) months and (83.291±4.991) months (χ(2)=6.406, P=0.011) , respectively. Conclusion: Age>60 years and CVF were risk factors for thrombotic event. CALR mutation was a protective factor for thrombotic event. Age >60 years was a risk factor for OS in ET patients.