The constitutively active Janus kinase 2 mutant Jak2-V617F is responsible for cytokine-independent growth of hematopoietic cells and the development of myeloproliferative neoplasms, such as polycythaemia vera and essential thrombocythaemia.
One of the major genetic insights into the pathogenesis of polycythaemia vera included the identification of the somatic point gain-of-function mutations in Janus kinase 2 gene-first <i>JAK2V617F</i> on exon 14, present in 95%-97% of the cases, and later on exon 12.
The World Health Organization classification system recognizes 4 variants of JAK2 mutation-enriched myeloproliferative neoplasms (for expansion of gene symbols, use search tool at www.genenames.org): essential thrombocythemia (ET), polycythemia vera (PV), primary myelofibrosis (PMF), and prefibrotic PMF.
We retrospectively examined the clinical and biological characteristics of 13 patients with concomitant CLL and MPN--eight primary myelofibrosis (PMF), three essential thrombocytosis (ET), and two polycythemia vera (PV)--who presented to our institution between 1998 and 2014, and tested all patients for MPN-specific aberrations, such as JAK2, MPL and CALR mutations.
Polycythemia vera (PV), essential thrombocythemia (ET) and primary myelofibrosis (PMF) are classical myeloproliferative neoplasms (MPN), characterized by specific somatic mutations in JAK2, CALR or MPL genes.
Two additional SNPs, rs2736100 (TERT) and rs9376092 (HBS1L/MYB), achieve genome-wide significance when including JAK2(V617F)-positive cases. rs9376092 has a stronger effect in JAK2(V617F)-negative cases with CALR and/or MPL mutations (Breslow-Day P=4.5 × 10(-7)), whereas in JAK2(V617F)-positive cases rs9376092 associates with essential thrombocythemia (ET) rather than polycythemia vera (allelic χ(2) P=7.3 × 10(-7)).
The etiology of myeloproliferative neoplasms (MPN) (polycythemia vera; essential thrombocythemia; primary myelofibrosis) is unknown, however they are associated with a somatic mutation--JAK2V617F--suggesting a potential role for environmental mutagens.
We studied samples from 1088 persons with myeloproliferative neoplasms (MPNs) including 421 JAK2(V617F) negative subjects with ET, PMF, polycythemia vera (PV), chronic myeloid leukemia (CML) and hyper-eosinophilic syndrome (HES).
Five patients had long-standing ET (three were calreticulin (CALR)-positive, one janus kinase 2 (JAK2)-positive, and one JAK2-negative and CALR-negative), and one had long-standing JAK2-positive PV prior to starting Peg-IFN.
Since the discovery of the JAK2V617F mutation in the majority of the myeloproliferative neoplasms (MPN) of polycythemia vera, essential thrombocythemia and primary myelofibrosis ten years ago, further MPN-specific mutational events, notably in JAK2 exon 12, MPL exon 10 and CALR exon 9 have been identified.