Polycythemia VeraPolycythemiaSplenomegalyPrimary MyelofibrosisThrombocythemia, EssentialJanus Kinase 2Myeloproliferative DisordersThrombocytosisPipobromanJanus KinasesErythroid Precursor CellsAloeErythropoietinPyrazolesPhlebotomyReceptors, ThrombopoietinErythropoiesisGranulocytesReceptors, ErythropoietinThrombosisHydroxyureaHematocritBloodlettingHematopoiesis, ExtramedullaryMutation, MissenseJanus Kinase 1Protein Kinase InhibitorsThrombocytopeniaMutationErythroid CellsPlatelet CountAmino Acid SubstitutionGPI-Linked ProteinsMegakaryocytesSplenectomyColony-Forming Units AssayBone MarrowBudd-Chiari SyndromeIsoantigensLeukocytosisLeukemia, Myeloid, Chronic, Atypical, BCR-ABL NegativeChromosomes, Human, 19-20ThrombopoietinHomozygoteHematopoietic Stem Cells