Prevalence of overt myeloproliferative neoplasms and JAK2 V617F mutation in Korean patients with splanchnic vein thrombosis

The molecular landscape of myeloproliferative neoplasms associated with splanchnic vein thrombosis: Current perspective

BCR::ABL1-negative myeloproliferative neoplasms (MPNs) are classically represented by polycythemia vera, essential thrombocythemia, and primary myelofibrosis. BCR::ABL1-negative MPNs are significantly associated with morbidity and mortality related to an increased risk of thrombo-hemorrhagic events. They show a consistent association with splanchnic vein thrombosis (SVT), either represented by the portal, mesenteric or splenic vein thrombosis, or Budd-Chiari Syndrome. SVT is also a frequent presenting manifestation of MPN. MPNs associated with SVT show a predilection for younger women, high association with JAK2V617F mutation, low JAK2V617F variant allele frequency (generally <10 %), and low rates of CALR, MPL, or JAK2 exon 12 mutations. Next-Generation Sequencing techniques have contributed to deepening our knowledge of the molecular landscape of such cases, with potential diagnostic and prognostic implications. In this narrative review, we analyze the current perspective on the molecular background of MPN associated with SVT, pointing as well future directions in this field.

Impact of JAK2V617F Mutation Burden on Disease Phenotype in Chinese Patients with JAK2V617F-positive Polycythemia Vera (PV) and Essential thrombocythemia (ET)

Most patients with polycythemia vera (PV) and half of essential thrombocythemia (ET) possess an activating JAK2V617F mutation. The objective of this study was to better define the effect of JAK2V617F mutant allele burden on clinical phenotypes in Chinese patients, especially thrombosis. By real-time polymerase chain reaction (RT-PCR), the JAK2V617F mutation burden was detected in 170 JAK2V617F-positive patients, including 54 PV and 116 ET. The results showed that JAK2V617F allele burden was higher in PV than in ET (P< 0.001). Higher percentage of patients had JAK2V617F allele burden over 20% in PV than in ET (68.5% VS 26.7%) (P< 0.001). In PV patients, higher JAK2V617F allele burden was observed in female (P< 0.05) and leukocytosis patients (WBC above 10 × 10(9)/L) (P< 0.001). Meanwhile, ET patients showed increased JAK2V617F allele burden in the group with higher hemoglobin (HGB above 150 g/L) (P< 0.05), leukocytosis (WBC above 10 × 10(9)/L) (P< 0.001), splenomegaly (P< 0.05) and thrombosis (P< 0.05). In conclusion, the JAK2V617F mutation allele burden is higher in Chinese patients with PV than ET. In PV patients, JAK2V617F mutation burden had influence on WBC counts. And the clinical characteristics of ET patients, such as WBC counts, hemoglobin level, splenomegaly and thrombosis, were influenced by JAK2V617F mutation burden. Male, high hemoglobin (HGB above 150 g/L), and increased JAK2V617F mutation burden (JAK2V617F allele burden ≥ 16.5%) were risks of thrombosis (P< 0.05) for ET patients by Logistic Regression.