Polycythemia VeraPolycythemiaThrombocythemia, EssentialJanus Kinase 2Primary MyelofibrosisMyeloproliferative DisordersPipobromanThrombocytosisErythroid Precursor CellsAloeErythropoietinPhlebotomyReceptors, ThrombopoietinErythropoiesisGranulocytesReceptors, ErythropoietinThrombosisHydroxyureaBloodlettingHematocritMutation, MissenseMutationHematopoiesis, ExtramedullaryAmino Acid SubstitutionErythroid CellsGPI-Linked ProteinsPlatelet CountMegakaryocytesJanus KinasesColony-Forming Units AssayBudd-Chiari SyndromeIsoantigensLeukemia, Myeloid, Chronic, Atypical, BCR-ABL NegativeThrombopoietinChromosomes, Human, 19-20Bone MarrowHematopoietic Stem CellsHomozygoteSplenomegalySTAT5 Transcription FactorProtein-Tyrosine Kinases