Our bodies produce billions of blood cells every day. Stem cells inside our bone marrow produce the blood cells our bodies need: red blood cells, white blood cells and platelets. Each type of cell has a specific function in our bodies. When a person has a myeloproliferative disorder, something goes wrong with blood cell production, resulting in too many or too few blood cells.

The three most common MPDs are:

ET (essential thrombocythaemia) - When a person has ET, the blood contains too many platelets, the cells that cause clotting.

PV (polycythaemia vera) - When someone has PV, his or her blood contains too many red cells, the cells that contain haemoglobin and carry oxygen from the lungs to the rest of the body. People with PV often produce excess white blood cells and platelets as well.

MF (myelofibrosis) - People with MF have scarring or fibrosis in their bone marrow. The bone marrow often produces inadequate numbers of blood cells.

Read more: Essential thrombocythaemia (ET), Polycythaemia Vera (PV)) Myelofibrosis (MF)