Primary familial and congenital polycythemia

Other Names: Familial erythrocytosis; Primary congenital erythrocytosis; Familial erythrocytosis type 1; ECYT1; Polycythemia, primary familial and congenital; PFCP; Erythrocytosis autosomal dominant benign; Congenital polycythemia due to erythropoietin receptor mutation; Congenital erythrocytosis due to erythropoietin receptor mutation; Autosomal dominant familial erythrocytosis-1; Familial erythrocytosis 1; Primary familial polycythemia

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.

Cause

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. The EPOR gene provides instructions for making a protein known as the erythropoietin receptor, which is found on the surface of certain blood-forming cells in the bone marrow. Erythropoietin is a hormone that directs the production of new red blood cells. Erythropoietin fits into the receptor like a key into a lock, triggering signaling pathways that lead to the formation of red blood cells. Mutations in the EPOR gene cause the erythropoietin receptor to be turned on for an abnormally long time after attaching to erythropoietin. The overactive receptor signals the production of red blood cells even when they are not needed, which results in an excess of these cells in the bloodstream. When familial erythrocytosis is caused by mutations in the EPOR gene, it is known as ECYT1.

Inheritance

Autosomal dominant pattern, a 50/50 chance.

PFCP is inherited in an autosomal dominant manner, but some people with PFCP have no relatives with the disease.

Signs and symptoms

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. For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed.

80%-99% of people have these symptoms

• Abnormal hemoglobin
• Epistaxis(Bloody nose)
• Fatigue(Tired)
• Headache(Headaches)
• Polycythemia(Increased red blood cells)
• Venous thrombosis(Blood clot in vein
• Vertigo(Dizzy spell)

30%-79% of people have these symptoms

• Abdominal pain(Pain in stomach)
• Arthralgia(Joint pain)
• Pruritus(Itching)

5%-29% of people have these symptoms

• Cough(Coughing)
• Exertional dyspnea
• Thromboembolism

Diagnosis

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).

Treatment

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).

NIH genetic and rare disease info

• NIH info on Primary familial and congenital polycythemia

Primary familial and congenital polycythemia is a rare disease.

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