This information is provided by the National Institutes of Health (NIH) Genetic and Rare Diseases Information Center (GARD).
Primary familial and congenital polycythemia (PFCP) is an inherited blood disease that causes uncontrolled production of red blood cells (erythrocytes). This leads to an increased volume of red blood cells compared to the total blood volume (erythrocytosis). It may also lead to increased total blood volume or increased blood thickness (hyperviscosity), both of which can cause symptoms. The disease is present at birth, but symptoms (if they develop) may arise any time during childhood or adulthood. Possible symptoms may include headaches, dizziness, fatigue, nosebleeds, difficulty breathing after physical activity, muscle pain, a reddish complexion, and altered mental status. Some people develop blood clots that can block various blood vessels, preventing adequate blood flow (thromboembolic events). Most people have mild symptoms, but some people experience life-threatening complications such as heart attack or stroke. The risk of thrombosis and severe complications increases with age.
PFCP is diagnosed by blood tests detecting isolated erythrocytosis and low EPO levels, in the absence of spleen abnormalities and other underlying diseases that can cause erythrocytosis (such as certain blood diseases and blood cancers).
PFCP is inherited in an autosomal dominant manner, but some people with PFCP have no relatives with the disease. In about 12-15% of people with PFCP, it is caused by mutations in the EPOR gene. However in most people, the genetic cause is not yet known.
Most people with PFCP do not need ongoing treatment. Some people with high blood volume need to have blood drawn periodically (phlebotomy) to treat symptoms or to maintain close-to-normal hematocrit levels. Some people with PFCP need medicines to lower blood pressure (antihypertensive therapy).
For more information, visit GARD.