Polycythemia VeraPolycythemiaThrombocythemia, EssentialJanus Kinase 2Primary MyelofibrosisMyeloproliferative DisordersThrombocytosisPipobromanErythroid Precursor CellsErythropoietinPhlebotomyReceptors, ThrombopoietinErythropoiesisAloeReceptors, ErythropoietinGranulocytesHematocritBloodlettingThrombosisHydroxyureaHematopoiesis, ExtramedullaryMutation, MissenseMutationGPI-Linked ProteinsErythroid CellsAmino Acid SubstitutionPlatelet CountColony-Forming Units AssayMegakaryocytesHomozygoteIsoantigensVon Hippel-Lindau Tumor Suppressor ProteinBudd-Chiari SyndromeBone MarrowLeukemia, Myeloid, Chronic, Atypical, BCR-ABL NegativeChromosomes, Human, 19-20ThrombopoietinHematopoietic Stem CellsErythrocyte VolumeSplenomegalyLeukocytosis