Immature bone marrow cells called blasts normally develop into several types of blood cells that serve different purposes. In MDS, the bone marrow produces too many identical, abnormal blasts. The body destroys the abnormal cells, and not enough normal red or white blood cells or platelets are made. Too few red blood cells, which carry oxygen from the lungs to the tissues, result in anemia. White blood cells help fight infection.
Platelets are necessary for blood clotting.
MDS is sometimes called sideroblastic anemia. MDS used to be called preleukemia because it can worsen and become a type of leukemia, a cancer of the blood that is usually fatal. Myelodysplastic syndromes are grouped together into five types, based on how the bone marrow cells or blood cells look. It can change from one type to another. In most of these cases, the condition is so mild it does not require treatment.