Polycythemia VeraLeukocytosisPolycythemiaThrombocythemia, EssentialJanus Kinase 2Primary MyelofibrosisMyeloproliferative DisordersThrombocytosisPipobromanErythroid Precursor CellsAloeErythropoietinPhlebotomyReceptors, ThrombopoietinErythropoiesisLeukemoid ReactionGranulocytesLeukocyte CountThrombosisHematocritReceptors, ErythropoietinHydroxyureaSplenomegalyBloodlettingPlatelet CountMutationMutation, MissenseHematopoiesis, ExtramedullaryBone MarrowErythroid CellsAmino Acid SubstitutionGPI-Linked ProteinsMegakaryocytesColony-Forming Units AssayBudd-Chiari SyndromeHematopoietic Stem CellsIsoantigensLeukemia, Myeloid, Chronic, Atypical, BCR-ABL NegativeChromosomes, Human, 19-20ThrombopoietinHomozygote