JAK2 and myeloproliferative disorder: Occurrence of a somatic activating mutation valine to phenylalanine (V617F) in the pseudokinase (JH2) domain of JAK2 has been implicated in myeloproliferative neoplasms including polycythemia vera (PV, 90%), essential thrombocythemia (ET, 50%) and primary myelofibrosis (PMF, 50%) [3, 4, 5, 6].