Acquired mutation of the tyrosine kinase JAK2V617F in Egyptian patients with myeloid disorders

Analysis of JAK2 V617F mutation in Tunisian patients with myeloproliferative neoplasms

We aimed to investigate the prevalence of the JAK2 V617F mutation in Tunisian patients with myeloproliferative neoplasms (MPN) and to look for possible associations with diseases’ presentation. In this context, JAK2 V617F polymorphism was detected by PCR-RFLP and direct sequencing in 213 MPN patients (109 with polycythemia vera (PV), 93 with essential thrombocythemia (ET) and 11 with primary myelofibrosis (PMF)), 77 unclassified patients with thrombosis (UPT) and 95 healthy control subjects. The JAK2 V617F mutant allele was present by either PCR-RFLP or direct sequencing in 158 (74.17%) MPN patients while all UPT and controls were negative. Besides, the JAK2 V617F mutation was significantly more frequent in patients with PV 98 (89.9%) than in ET 54 (58.1%) and PMF 6 (54.5%) groups, p < 0.001. Analytic results in MPN patients showed significant associations between the JAK2 SNP and both hemoglobin levels (16.29 ± 3 vs 13.01 ± 3.65) and hematocrit (52.99 ± 8.34 vs 45.37 ± 10.94), p < 0.001 and p < 0.001, respectively. In addition, in the ET subgroup thrombosis was significantly more frequent in patients carrying the V617F mutation (16, (29.6%) vs 3, (7.7%)), p = 0.01. In ET patients, the V617F mutation seems to be predictive of thrombosis occurrence.

Frequency of Zygosity in Jak-2 Positive Patients with Polycythemia Vera-Pakistan's Perspective

BACKGROUND

Estimation of JAK2V617F mutational load in Polycythemia Vera (PV) helps to determine the severity of the disease phenotype, the risk of thrombotic events, progression to post-PV myelofibrosis and survival. Amplification Refractory Mutation Screening (ARMS) PCR or Allele Specific (AS) PCR is a simple easy method with a reasonable sensitivity for screening of zygosity.The purpose of this study was to see the frequency of disease burden and phenotypic characteristics in Pakistani patients diagnosed with JAK2V617F mutation positive PV.

MATERIALS AND METHODS

A cross-sectional study using non probability consecutive sampling was conducted at Hematology Department, Liaquat National Hospital Karachi from October 2018 to July 2019.Adult newly diagnosed JAK2V617F positive PV patients of either gender were included. Patients' demographics, clinical characteristics and baseline CBC were noted. JAK2V617F zygosity was qualitatively analyzed by ARMS-PCR technique. Age and gender were stratified to see to see the result of qualitative and quantitative effect modifiers on these patients using Chi Square and fisher exact test as appropriate while mean comparison was done by independent t-test and one way ANOVAtest. P value of ≤0.05 was considered as significant.

RESULTS

Fifty one patients were included in the study with an average age of 59.60±14.29years.90.2% of patients had hypertension.All patients tested positive for heterozygous state. Significant association of gender was found with smoking (p=0.001) while age was significantly linked with hypertension (p-0.033).

CONCLUSION

JAK2V617F positive PV patients are mainly heterozygous males showing significant association with smoking and hypertension. ARMS-PCR is a robust technique to determine zygosity which can be used for screening purposes.<br />.

Portal vein thrombosis due to essential thrombocythemia with limited cutaneous systemic sclerosis

Portal vein thrombosis is caused by various diseases, including liver cirrhosis, cancer, abdominal infection, and myeloproliferative disorders. Essential thrombocythemia is one of the myeloproliferative disorders in which the bone marrow produces excessive amount of platelets and can be accompanied by various thrombotic diseases; however, essential thrombocythemia with limited cutaneous systemic sclerosis has not been reported yet. We herein report a case of extensive portal vein thrombosis due to essential thrombocythemia with limited cutaneous systemic sclerosis. A 49-year-old woman was referred to our hospital due to liver dysfunction. Extended portal vein thrombosis, splenomegaly, and thrombocytosis were founded. The examination of Janus kinase 2 V617F mutation in the bone marrow was positive. These findings resulted in the diagnosis of portal vein thrombosis due to essential thrombocythemia. Furthermore, Raynaud's phenomenon, finger's sclerosis, and positive anti-centromere antibody led to limited cutaneous systemic sclerosis. To further analyze the causal relationship between essential thrombocythemia and limited cutaneous systemic sclerosis, platelet-derived growth factor was examined. High level of serum platelet-derived growth factor, possibly caused by high platelet count due to essential thrombocythemia, was observed. As platelet-derived growth factor has been reportedly associated with the occurrence of systemic sclerosis, the present case indicates the possible causal link between essential thrombocythemia and limited cutaneous systemic sclerosis through high platelet-derived growth factor.

MPL W515 L/K mutations in myeloproliferative neoplasms

Background

Myeloproliferative neoplasms (MPNs) describe a group of diseases involving the bone marrow (BM). Classical MPNs are classified into chronic myelogenous leukemia (CML), polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF). This classification is based on the presence of Philadelphia (Ph) chromosome (BCR/ABL1). CML is BCR/ABL1-positive while PV, ET, and PMF are negative. JAK2 p. Val617Phe pathological variant is the most associated mutation in BCR/ABL1-negative MPNs. The frequency of JAK2 p. Val617Phe is 90–95% in PV patients, 50–60% in ET, and 40–50% in patients with PMF. Studies on MPL gene led to the revelation of a gain of function pathological variants in JAK2 p. Val617Phe-negative myeloproliferative neoplasms (MPNs). MPL p. W515 L/K pathological variants are the most common across all mutations in MPL gene. The prevalence of these pathological variants over the Egyptian population is not clear enough. In the present study, we aimed to investigate the prevalence of MPL p. W515 L/K pathological variants in the Philadelphia (Ph)-negative MPNs over the Egyptian population.

Results

We have tested 60 patients with Ph-negative MPNs for MPL p. W515 L/K pathological variants. Median age was 51 (22–73) years. No MPL p. W515 L/K pathological variants were detected among our patients. JAK2 p. Val617Phe in PV and PMF patients showed significantly lower frequency than other studies. Splenomegaly was significantly higher in ET patients compared to other studies.

Conclusion

MPL p. W515 L/K pathological variants are rare across the Egyptian Ph-negative MPNs, and further studies on a large number are recommended. MPN patients in Egypt are younger compared to different ethnic groups.

Polycythaemia Vera among Sudanese Patients with Special Emphasis on JAK2 Mutations

Background: In recent years, a somatic point mutation in the Janus Kinase 2 (JAK2) gene (1849 G→T, V617F) has been reported to occur in over 90% of patients with polycythemia vera (PV). Another JAK2 mutation in exon 12 had been described and shown capable of activating erythropoietin signaling pathways. Objective: In this study, we aimed to determine the frequency of Jak2 mutations (JAK2V617F and JAK2 exon 12) as well as their relationships with hematological parameters in Sudanese patients with myeloproliferative disorders (MPD). A comparison with findings of published studies from other geographic regions was included. Materials and Methods: From each of a total of 83 polycythaemia patients, six milliliters (ml) of venous blood were collected and processed for molecular analysis and measurement of serum erythropoietin level by enzyme-linked immunoassay (ELISA). The JAK2 V617F mutation was determined using an allele-specific competitive blocker (ACB) -PCR assay and High Resolution Melting (HRM) analysis was applied for the JAK2 exon 12 mutation. Results: According to patients’ history and the results for EPO levels, nine (10.7 %) out of 83 patients were found to have secondary polycythaemia and 74 (89.3%) PV. The overall frequency of the 2 JAK2 mutations was 94.6% in our Sudanese PV patients, JAK2V617F being found in 91% and JAK2 exon 12 mutations in 8.1%.Conclusion: In summary JAK2 V617F and JAK2 exon 12 mutations are very common in Sudanese PC cases.

JAK-2 V617F Mutational Analysis in Primary Idiopathic Myelofibrosis: Experience from Southern Pakistan

BACKGROUND

Primary idiopathic myelofibrosis (PMF) is a clonal Ph-chromosome negative myeloproliferative neoplasm characterized by dysregulated kinase signaling and release of abnormal cytokines. In the recent past, following JAK2 V617F mutation invention, important revolution has been made in the molecular diagnostic biology of this disease. The rational of this study was to determine the mutational status of JAK2 V617F in Pakistan patients with PMF.

MATERIALS AND METHODS

In this cross sectional study, 20 patients with PMF were enrolled from January 2011 to December 2014. Diagnosis was based on WHO criteria for PMF. All patients were screened for G-T point mutation (V617F) in the JAK2 gene on chromosome 9 by allele specific PCR.

RESULTS

The mean age was 57.9 ± 16.5 years. The male to female ratio was 3:1. The frequency of JAK2 V617F positivity in our PMF patients was found to be 55%. Positive correlations of JAK2 V617F mutation were established with high TLC count, raised LDH and marked splenomegaly (P<0.05). No correlation of JAK2 V617F could be established with age and gender (P>0.05).

CONCLUSIONS

The JAK2 V617F mutation frequency in our PMF patients was similar to those reported previously. In our hands JAK2 V617F mutated patients expressed an aggressive disease phenotype. Screening for the mutation in all suspected PMF cases could be beneficial in differentiating patients with reactive and clonal marrow fibrosis.

Acquired JAK-2 V617F Mutational Analysis in Pakistani Patients with Essential Thrombocythemia

BACKGROUND

Essential thrombocythemia (ET) is a clonal hemopoietic stem cell myeloproliferative neoplasm characterized by persistent thrombocytosis along with megakaryocytic hyperplasia. In the last decade following the identification of an acquired JAK2 V617F mutation, there has been acceleration in our understanding of this disease. The rational of this study was to determine the mutational profile of JAK2 V617F in Pakistan patients with ET.

MATERIALS AND METHODS

In this retrospective cross sectional study, 21 patients with ET were enrolled from January 2011 to December 2014. Patients were diagnosed based on WHO criteria for essential thrombocythemia. Complete blood count was done on an automated hematology analyzer, while JAK2 V617F expression was evaluated by polymerase chain reaction.

RESULTS

The mean age was 56.7±19.0 years (range 18-87) and the male to female ratio was 1:1.1. The frequency of JAK2 V617F positivity in our ET patients was found to be 61.9%. The mean hemoglobin was 11.7±2.4 g/dl with a total leukocyte count of 13.3±8.1x109/l and a platelet count of 1188±522x109/l. Positive correlations for JAK2 V617F mutation were established with high TLC count and raised LDH (P<0.05). No correlation of JAK2 V617F could be established with age and gender (P>0.05).

CONCLUSIONS

JAK2 V617F mutation frequency in our ET patients was similar to those reported previously. Screening for the mutation in all suspected essential thrombocythemia cases could be beneficial in differentiating patients with reactive and clonal thrombocytosis.

JAK2 V617F mutation prevalence in myeloproliferative neoplasms in Pernambuco, Brazil

BACKGROUND

The JAK2 V617F mutation is associated with three myeloproliferative neoplasms (MPNs): polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF). It generates an unregulated clonal hematopoietic progenitor and leads to abnormal increased proliferation of one or more myeloid lineages. Subjects bearing this mutation may present more frequently with complications such as thrombosis and bleeding, and no specific treatment has yet been developed for BCR-ABL-negative JAK2 V617F-negative MPNs.

AIMS

To determine the prevalence of JAK2 V617F in MPNs in Pernambuco, Brazil, and to compare it with previous studies.

MATERIAL AND METHODS

144 blood samples were collected at the Hospital of Hematology of the HEMOPE Foundation and were genotyped by polymerase chain reaction-restriction fragment length polymorphism with BsaXI enzymatic digestion.

RESULTS AND DISCUSSION

88% (46/52) of the patients with PV, 47% (39/81) with ET, and 77% (8/11) with PMF were positive for JAK2 V617F, while more than 35% of the individuals were JAK2 V617F-negative, confirming a high prevalence of this abnormality in MPNs, more frequently with a low mutated allele burden, similar to what has been reported in other Western countries, despite differences among methods used to detect this mutation. Screening for JAK2 V617F may allow specific management of these diseases with JAK2 inhibitors in the future and highlights the need for further studies on the pathogenesis of BCR-ABL-negative JAK2 V617F-negative MPNs.

Nuclear JAK2: form and function in cancer

The conventional view of Janus kinase 2 (JAK2) is a nonreceptor tyrosine kinase which transmits information to the nucleus via the signal transducer and activator of transcriptions (STATs) without leaving the cytoplasm. However, accumulating data suggest that JAK2 may signal by exporting from cytoplasm to nucleus, where it guides the transcriptional machinery independent of STATs protein. Recent studies demonstrated that JAK2 is a crucial component of signaling pathways operating in the nucleus. Especially the latest landmark discovery confirmed that JAK2 goes into the nucleus and directly interacts with nucleoproteins, such as histone H3 at tyrosine 41 (H3Y41), nuclear factor 1-C2 (NF1-C2) and SWI/SNF-related helicases/ATPases (RUSH)-1α, indicating that JAK2 has a fresh nuclear function. Nuclear JAK2 is linked to a variety of cellular functions, such as cell cycle progression, apoptosis and genetic instability. The balance between these functions is an essential factor in determining whether a cell remains benign or becomes malignant. The aim of this review is intended to summarize the state of our knowledge on nuclear localization of JAK2 and nuclear JAK2 pathways, and to highlight the emerging roles for nuclear JAK2 in carcinogenesis.