What are MPNs?
Myeloproliferative Neoplasms (MPNs) are a group of rare conditions that affect the blood. In MPNs, something goes wrong with the normal production of blood cells, the bone marrow may produce too many of one or more particular types of blood cell or in some cases too few blood cells.
The bone marrow is the spongy material inside the bones where new blood cells are produced. The normal process of blood cell production starts with a stem cell, which is an immature cell that can develop into all types of blood cell. When the stem cell divides, it can either produce more stem cells or produce immature blast cells with the potential to further develop and mature.
The immature blast cells can mature and develop in the bone marrow to become the three types of blood cells: red blood cells, white blood cells, or platelets. All blood cells have an important function.
- Red blood cells (also called erythrocytes) – carry oxygen around the body to organs and tissues.
- White blood cells (also called leukocytes) – protection against illness & disease by fighting infections.
- Platelets (also called thrombocytes) – help blood clot to prevent bruising and bleeding.
Myeloproliferative Neoplasms facts
- Approximately, 4,180 are diagnosed with MPN in the UK each year.
- Polycythaemia vera (PV) is rarely diagnosed before the age of 40 years and more common in men than women.
- Essential thrombocythaemia (ET) is most commonly diagnosed in people over 60 years.
- Myelofibrosis can affect anyone but it is most common in people over 50 years.
The World Health Organisation (WHO) classifies MPNs as a type of blood cancer because the bone marrow produces blood cells in an uncontrolled way.
The three common types of MPNs are separated into different disorders as each of them affect levels of blood cell in a different way. The three most frequently diagnosed types of MPN are:
- Polycythaemia vera (PV)
- Essential thrombocythaemia (ET)
- Myelofibrosis (MF)
Polycythaemia vera (PV)
In 30% of people with PV, the excess number of red blood cells may cause blood clots to form more easily making the person more susceptible to a stroke or heart attack.
Essential thrombocythaemia (ET)
In people diagnosed with ET, the blood becomes thicker than normal, and the excess number of platelets may cause blood clots to form more easily. Clots may block blood flow through veins and arteries, potentially leading to heart attacks or strokes. ET is also associated with an increased risk of bleeding complications.
There are two main types of MF: