[The role of driver and subclonal mutations in pathogenesis of primary myelofibrosis]. / A driver és szubklonális mutációk szerepe a primer mielofibrózis patogenezisében.

Primary myelofibrosis (PMF) is a Philadelphia chromosome negative, clonal myeloproliferative neoplasm characterised by a progressive nature. Morphologically, the bone marrow biopsy shows features of abnormal proliferation of terminally differentiated megakaryocytes and subsequent bone marrow fibrosis. The molecular landscape of PMF includes phenotypic driver mutations (JAK2 V617F, CALR and MPL) which represent major diagnostic criteria, and subclonal mutations that also occur in several other myeloid diseases, but have a prognostic value in disease progression of MF. The most important subclonal mutations affect the genes ASXL1, TET2, IDH1/2, EZH2 and TP53. Triple negative genotype and the high molecular risk genotype and CALR-/ASXL1+ are associated with adverse survival with the latest indicating stem cell transplantation independently of the DIPSS-plus score.

Calreticulin mutation specific CAL2 immunohistochemistry accurately identifies rare calreticulin mutations in myeloproliferative neoplasms.

Mutations of the multifunctional protein calreticulin (CALR) are recognised as one of the main driver alterations involved in the pathogenesis of Philadelphia negative myeloproliferative neoplasms (Ph- MPN) and also represent a major diagnostic criterion in the most recent World Health Organization classification of myeloid neoplasms. Nowadays, quantitative assessment of the driver mutations is gaining importance, as recent studies demonstrated the clinical relevance of the mutation load reflecting the size of the mutant clone. Here, we performed for the first time a manual and automated quantitative assessment of the CALR mutation load at protein level using CAL2, a recently developed CALR mutation specific monoclonal antibody, on a cohort of 117 patients with essential thrombocythemia (ET) or primary myelofibrosis (PMF) and compared the CALR protein mutation loads with the CALR mutation load values established by a molecular assay. Eighteen different CALR mutations were detected in the cohort of the 91 CALR mutant cases. Mutation loads of the CALR mutations were between 13% and 94% with mean value in PMF cases significantly higher than ET cases (49.94 vs 41.09; t-test, p=0.004). Cases without CALR mutation (n=26) showed no or only minimal labelling with the CAL2 antibody, while all 18 different types of CALR mutations were associated with CAL2 labelling. The CALR mutation load showed a significant correlation (p=0.03) with the occurrence of major thrombotic events, with higher mutation load in patients presenting with these complications. We report a 100% concordance between the mutation status determined by immunohistochemistry and the CALR molecular assay, and we extend the applicability of this approach to 16 rare CALR mutations previously not analysed at protein level.

Detection of high-risk thrombophilia with an automated, global test: the Coagulation Inhibitor Potential assay.

: The diagnosis of thrombophilia is a cost-consuming and time-consuming process, as each defect should be separately investigated. The Coagulation Inhibitor Potential (CIP) assay is a promising new global test, sensitive for most of the hereditary thrombophilias, developed for manual methodology. We adapt the original method to an optical coagulation analyser. By this automation, the test will be easier, faster and more precise, and it also allows carrying out 18 measurements simultaneously. The CIP assay was performed in 126 healthy subjects and 193 patients with different types of hereditary thrombophilia conditions. Detected with conventional laboratory tests high-risk thrombophilia was present in 70 patients: deficiencies of antithrombin (AT) (n = 12), protein C (PC) (n = 14), protein S (PS) (n = 6), homozygous factor V Leiden (FVL) mutation (n = 9) and combined types (n = 29). Low-risk thrombophilia was present in 123 patients: heterozygous FVL (n = 115) and FII G2010A mutation (n = 8). Significantly lower median CIP values were found for AT-,PC-, PS deficiencies, homozygous and heterozygous FVL mutations and combined thrombophilias (P < 0.01) as compared with healthy controls. There was no significant difference between the heterozygous FIIG20210A (P = 0.669) thrombophilia group and the healthy controls. The best performance of the test was achieved at the cut-off value of 90.0 U (area: 0.981) with 96% sensitivity and 92% specificity in the high-risk thrombophilia group estimated by receiver operating characteristic analysis. The new method seems to be appropriate and reliable for the detection of AT-, PC- and PS deficiencies, homozygous FVL mutation and also for combined deficiencies. The automated CIP test is insensitive to FII G2010A mutation.

Quantitative assessment of JAK2 V617F and CALR mutations in Philadelphia negative myeloproliferative neoplasms.

BACKGROUND: Philadelphia negative myeloproliferative neoplasms (MPNs) are characterized by frequent mutations of driver genes including JAK2, CALR and MPL. While the influence of JAK2 V617F mutant allele burden on the clinical phenotype of MPN patients is well-described, the impact of CALR mutant allele burden on clinical features needs further investigation. PATIENTS AND METHODS: Quantitative assessment of JAK2 and CALR mutations was performed on diagnostic DNA samples from 425 essential thrombocythemia (ET) and 227 primary myelofibrosis patients using real-time quantitative PCR and fragment length analysis. Characterization of CALR mutations and detection of MPL mutations were performed by Sanger sequencing. RESULTS: Twelve novel CALR mutations have been identified. ET patients with CALRmut load exceeding the median value exhibited lower hemoglobin values (12.0 vs. 13.6 g/dL), higher LDH levels (510 vs. 351 IU/L) and higher rate of myelofibrotic transformation (19% vs. 5%). The CALRmut load was higher among ET patients presenting with splenomegaly compared to those without splenomegaly (50.0% vs. 43.5%). CONCLUSION: Our study confirms the clinical significance of driver mutational status and JAK2mut load in MPNs; in addition, unravels a novel clinical association between high CALRmut load and a more proliferative phenotype in ET.

Challenges in the evaluation of D-dimer and fibrinogen levels in pregnant women.

INTRODUCTION: Normal pregnancy is associated with hypercoagulable state. Elevated markers of coagulation and fibrinolytic system activation indicate increased thrombin activity and increased fibrinolysis following fibrin formation throughout pregnancy. These changes exceed the biological variability in most cases. Haemostatic reference intervals are generally based on samples from non-pregnant women. Thus, they may not be relevant to pregnant women, a problem that may hinder accurate diagnosis and treatment of haemostatic disorders during pregnancy. The aim of the study was to follow the changes of haemostatic parameters and to establish gestational age-specific reference intervals during normal pregnancy. MATERIALS AND METHODS: Blood samples of 83 pregnant women were collected at gestational weeks 16, 26 and 36. Fibrinogen, D-dimer, and C-Reactive Protein (CRP) were examined. Reference intervals were calculated for fibrinogen, D-dimer tests with two different methods (mean±2 SD or median and 2.5th and 97.5th percentiles with 90% confidence intervals). RESULTS: fibrinogen and D-dimer increased progressively throughout pregnancy. Mean fibrinogen levels were higher than the maximum of the conventional reference interval, already in the 16th week of pregnancy. D-dimer levels were at or above the conventional cutoff point (250ng/mL) throughout the pregnancy in 42% of pregnant women, while in the 36th week 98% of them displayed elevated D-dimer levels. CRP did not increase in normal pregnancy. CONCLUSIONS: There seems to be an emerging need to reconsider fibrinogen and D-dimer values from a different aspect in pregnancy compared to non-pregnant reference intervals. New reference ranges are suggested to be established in pregnancy.