What is (are) Polycythemia vera ?
Polycythemia vera (PV) is a condition characterized by an increased number of red blood cells in the bloodstream. Affected people may also have excess white blood cells and platelets. These extra cells cause the blood to be thicker than normal, increasing the risk for blood clots that can block blood flow in arteries and veins. People with PV have an increased risk of deep vein thrombosis which can cause a pulmonary embolism, heart attack, and stroke. Most cases of PV are not inherited and are acquired during a person's lifetime. In rare cases, the risk for PV runs in families and may be inherited in an autosomal dominant manner. The condition has been associated with mutations in the JAK2 and TET2 genes.