F5 and acquired polycythemia vera: Inherited forms include deficiencies in Protein C or S, Factor V Leiden, and antithrombin, while acquired causes are hematologic conditions like polycythemia vera, antiphospholipid syndrome, and paroxysmal nocturnal hemoglobinuria, as well as non-hematologic conditions such as malignancy, oral contraceptive use, pregnancy, nephrotic syndrome, and hyperhomocysteinemia.