JAK2 and acquired polycythemia vera: Abnormally increased or prolonged activation of the three pathways is implicated in deregulated erythropoiesis and overproduction of red blood cells in polycythemia vera and congenital erythrocytosis [59], wherein inherited mutations in the EPOR itself (ECYT1), and acquired mutations in JAK2 (PV) are already well known genetic causes [1,63].