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