Polycythemia VeraPolycythemiaThrombocythemia, EssentialJanus Kinase 2Primary MyelofibrosisMyeloproliferative DisordersThrombocytosisPipobromanErythroid Precursor CellsErythropoietinPhlebotomyReceptors, ThrombopoietinErythropoiesisAloeReceptors, ErythropoietinGranulocytesHematocritBloodlettingThrombosisHydroxyureaHematopoiesis, ExtramedullaryMutation, MissenseMutationGPI-Linked ProteinsErythroid CellsAmino Acid SubstitutionPlatelet Count