Bone marrow is the tissue inside the bones where blood cells are made.
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.