What is the main cause of Polycythemia vera?

Polycythemia vera is primarily caused by a bone marrow disorder that leads to the overproduction of erythrocytes (red blood cells). This condition is classified as a myeloproliferative neoplasm, where there is a mutation in the hematopoietic stem cells, particularly associated with the JAK2 V617F mutation in most cases. This mutation causes the bone marrow to produce excessive amounts of red blood cells independently of erythropoietin, the hormone that normally stimulates red blood cell production in response to low oxygen levels.

Other options, while relevant in a broader hematological context, do not accurately represent the primary cause of polycythemia vera. Chronic hypoxia typically induces erythropoietin production, which stimulates erythrocyte production to compensate for low oxygen. Reduced erythropoietin levels would not lead to an increase in red blood cell mass; instead, it is associated with conditions where red blood cell production is inadequate. Autoimmune destruction of red blood cells pertains more to conditions like autoimmune hemolytic anemia, which is distinct from polycythemia vera's underlying pathology. Thus, the emphasis on bone marrow overproduction of erythrocytes accurately describes the pathophysiological basis of