Clinical and laboratory features compared between JAK2 exon12 and JAK2 V617F mutated polycythemia vera / 中华血液学杂志

Objective: To compare clinical and laboratory features between JAK2 exon12 and JAK2 V617F mutated polycythemia vera (PV) . Method: We collected data from 570 consecutive newly-diagnosed subjects with PV and JAK2 mutation, and compared clinical and laboratory features between patients with JAK2 exon12 and JAK2 V617F mutation. Results: 543 (95.3%) subjects harboured JAK2 V617F mutation (JAK2 V617F cohort) , 24 (4.2%) harboured JAK2 exon12 mutations (JAK2 exon12 cohort) , and 3 (0.5%) harboured JAK2 exon12 and JAK2 V617F mutations. The mutations in JAK2 exon12 including deletion (n=10, 37.0%) , deletion accompanied insertion (n=10, 37.0%) , and missense mutations (n=7, 25.9%) . Comparing with JAK2 V617F cohort, subjects in JAK2 exon12 cohort were younger [median age 50 (20-73) years versus 59 (25-91) years, P=0.040], had higher RBC counts [8.19 (5.88-10.94) ×10(12)/L versus 7.14 (4.11-10.64) ×10(12)/L, P<0.001] and hematocrit [64.1% (53.7-79.0%) versus 59.6% (47.2%-77.1%) , P=0.001], but lower WBC counts [8.29 (3.2-18.99) ×10(9)/L versus 12.91 (3.24-38.3) ×10(9)/L, P<0.001], platelet counts [313 (83-1433) ×10(9)/L versus 470 (61-2169) ×10(9)/L, P<0.001] and epoetin [0.70 (0.06-3.27) versus 1.14 (0.01-10.16) IU/L, P=0.002] levels. We reviewed bone marrow histology at diagnosis in 20 subjects with each type of mutation matched for age and sex. Subjects with JAK2 exon12 mutations had fewer loose megakaryocyte cluster (40% versus 80%, P=0.022) compared with subjects with JAK2 V617F. The median follow-ups were 30 months (range 4-83) and 37 months (range 1-84) for cohorts with JAK2 V617F and JAK2 exon12, respectively. There was no difference in overall survival (P=0.422) and thrombosis-free survival (P=0.900) . Conclusions: Compared with patients with JAK2 V617F mutation, patients with JAK2 exon12 mutation were younger, and had more obvious erythrocytosis and less loose cluster of megakaryocytes.

Clinical significances of JAK2 mutation in patients with polycythemia vera / 中国肿瘤临床

Polycythemia vera (PV) is a myeloproliferative neoplasm (MPN) characterized by overproduction of red blood cells. The pathogenesis of PV is not completely understood. However, studies report that it may be associated with the gain-of-function somatic mutation of JAK2 and that the JAK2 mutation provides a molecular diagnostic standard for PV. JAK2 mutation and allele mutation bur-den are useful for predicting clinical features and courses. The discovery of JAK2 mutation has promoted the development of molecu-lar-targeted therapy, such as the JAK2 inhibitor, ruxolitinib, a drug with superior therapeutic effect and safety that is used in clinical practice. The JAK2 allele mutation burden is closely associated with leukocytosis and progression to myelofibrosis (MF). A high JAK2 al-lele mutation burden may be a risk factor for poor prognosis. This article briefly reviews the clinical significance of the JAK2 mutation in patients with PV.

Nucleophosmin mutation analysis in acute myeloid leukaemia: Immunohistochemistry as a surrogate for molecular techniques.

Background & objectives: Mutation of nucleophosmin (NPM1) gene in the absence of FLT3-ITD (FMS related tyrosine kinase 3 - internal tandem duplications) mutation carries a good prognosis in cytogenetically normal acute myeloid leukaemia (AML). NPM1, a multifunctional nucleolar phosphoprotein that shuttles between nucleus and cytoplasm, gets trapped in the cytoplasm when mutated. Immunohistochemical (IHC) demonstration of its aberrant cytoplasmic location (NPMc+) has been suggested as a simple substitute for the standard screening molecular method. This study was aimed to assess the diagnostic utility of IHC on formalin fixed bone marrow biopsies in comparison with the reference molecular method (allele specific oligonucleotide - polymerase chain reaction; ASO-PCR) to predict NPM1 mutation status in AML patients. Methods: NPM protein IHC was performed using mouse anti-NPM monoclonal antibody on 35 paraffin-embedded bone marrow biopsies of patients with primary AML of any French-American-British (FAB) subtype. Results of IHC were compared with those of ASO-PCR. Results: Of the 35 AML patients, 21 (60%) were positive for NPM1 exon 12 gene mutation by ASO-PCR, 19 (90.47%) of these 21 were NPMc+. Thirteen of the 35 patients were negative by both the methods. One NPMc+ patient was not detected by ASO-PCR. IHC had a sensitivity and specificity of 90 and 93 per cent, respectively, compared to the molecular screening gold standard. Interpretation & conclusions: Mutation of NPM1 determined by the widely available and inexpensive IHC agrees closely with results of the standard molecular methods. Thus, technically and financially not well endowed laboratories can provide the prognostically and potentially therapeutically important information on NPM1 mutation using IHC.

Correlation of Genomic Characteristic with Disease Progression in Polycythemia Vera / 天津医药

Objective To screen mutations in genes including ASXL1, TET2, IDH1, IDH2, SETBP1, MPL515, JAK2 exon 12 and JAK2V617 in 135 polycythemia vera (PV) patients. To assess progreasson and genomics characteristics post polycythemic myelofibrosis. Methods DNA sequencing of ASXL1(Exon12),TET2 (Exons 3-11),IDH1(Exon4),IDH2(Ex-on4),SEPBP1(Exon4),JAK2 exon 12 and MPL515 (Exon 10) genes were carried out using Sanger method. JAK2V617 muta-tion was detected by allele-specific PCR in patients with PV. In the mean time, the mutation load of JAK2V617F allele (V617F%) was evaluated by real-time PCR using Tagman MGB probe. Then, the significant of gene mutations and clinical outcomes of post-PV Myelofibrosis(PPMF)was analyzed. To study risk factors of PPMF, logistic regression were employed. Results ASXL1, TET2, IDH1, IDH2 were mutated in 7.69%(8/104), 5.26%(1/19) , 0.08%(1/120) and 0.08%(1/121) of all PV patient respectively. JAK2 was mutated in 82.22%(111/135) of PV patients with mutation rate of exon12 of 2.96%(4/135) and there were no mutation of MPL515 and SETBP1 in PV patients. ASXL1 mutation was found in 31.82%(7/22) PPMF patients. Spearman analysis showed that ASXL1 is correlated with JAK2V617F (V617F%) (rs=0.298,P=0.002). The hemo-globin was lower in patients with ASXL1 mutation than patient without mutation (wild type). Leukocyte count, V617F%>50%rate, thrombosis and PPMF were higher in patients with ASXL1 mutation than that of ASXL1 wild type(P＜0.05). ASXL1 mu-tation, V617F%>50% rate and splenomegaly were all risk factors of PPMF. Conclusion ASXL1 mutation is the risk-fac-tor of PPMF and may promote V617F%by some mechanism.

JAK2 V617F and Exon 12 Genetic Variations in Korean Patients with BCR/ABL1-negative Myeloproliferative Neoplasms / 대한진단검사의학회지

BACKGROUND: JAK2 genetic variations have been described in a high proportion of patients with BCR/ABL1-negative myeloproliferative neoplasms (MPN). This study was designed to analyze the frequencies of JAK2 V617F and exon 12 variations, and their correlations with clinical characteristics of Korean patients with BCR/ABL1-negative MPN. METHODS: We examined a total of 154 patients with BCR/ABL1-negative MPN that included 24, 26, 89, and 15 patients with polycythemia vera (PV), primary myelofibrosis (PMF), essential thrombocythemia (ET), and unclassified myeloproliferative neoplasms (MPNU), respectively. We performed allele-specific PCR to detect V617F in all BCR/ABL1-negative patients, and performed direct sequencing to detect exon 12 variations in 47 V617F-negative MPN patients. JAK2 c.1641+179_183del5 variation was detected by restriction fragment length polymorphism assay in 176 healthy subjects. RESULTS: JAK2 V617F was detected in 91 patients (59.1%): PV (91.6%), PMF (46.2%), ET (52.8%), and MPNU (66.7%). In V617F-negative MPN patients, no mutations were found in exon 12. The c.1641+179_183del5 was detected in 68.1% of V617F-negative MPN patients and 45.4% of healthy subjects (P=0.008). JAK2 V617F was closely correlated with age and leukocytosis in BCR/ABL1-negative MPN patients (P<0.05). However, c.1641+179_183del5 was not related to age, sex, or complete blood cell count parameters in V617F-negative MPN patients and healthy subjects. The c.1641+179_183del5 was associated with an increased odds ratio for MPN (odds ratio, 2.6; 95% confidences interval, 1.3-5.1; P=0.007). CONCLUSIONS: Frequencies of V617F are similar to reported results. JAK2 exon 12 mutations may be rare and c.1641+179_183del5 may influence the occurrence of MPN in Korean patients with V6 17F-negative MPN.