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