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