History of myeloproliferative disorder.
 History of polycythemia vera
(ROOT (NP (NP (NP (NN History)) (PP (IN of) (NP (JJ myeloproliferative) (NN disorder)))) (. .)))
(ROOT (NP (NP (NN History)) (PP (IN of) (NP (NN polycythemia) (NN vera)))))
( ( History ( of ( myeloproliferative disorder ) ) ) . )
( History ( of ( polycythemia vera ) ) )