Relier Pairs polycythemia veraVersion en ligne information about thus blood cancer par Kennedy Ellis 1 drawing blood 2 enlarged spleen 3 the mutation in which gene causes this blood cancer 4 what does polycythemia cause? 5 polycythemai vera 6 what do you experience? janus kinase 2 (JAK2) helps fight infection and filter unwanted material and gets bigger when there is too much RBCs heart attack or stroke increased number of red blood cells helps reduce # of RBCs itchiness, headches, dizziness, bleeding/bruising, weakness, fatigue