The expression of JAK2 mutation is seen in all conditions, EXCEPT:: (A) Chronic eosinophilic leukemia, (B) Primary myelofibrosis, (C) Polycythemia vera, (D) Essential thrombocytosis
Answer is A. Polycythemia vera (PV), Primary myelofibrosis (PMF) and Essential thrombocytosis (ET) are characterized by expression of a JAK2 mutation, V617F. It causes constitutive activation of tyrosine kinase. PV, PMF, and ET are transformed into acute leukemia very rarely. Ref: Harrison, Edition-18, Page-898