JAK2 and polycythemia: The current publications that studied polycythemia among different Saudi populations who live at different types of topography concluded that living in high altitudes, smoking, post-transplant erythrocytosis, the Janus kinase 2 (JAK2) mutation, and neonatal polycythemia are some of the most reported causes of different types of polycythemias in the kingdom.[7,8] PV, which is caused by an autonomous hyperproduction of red blood cells secondary to myeloproliferative neoplasm, is linked to a genetic mutation in (JAK2).