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