A group of disorders caused by blood cells that are poorly formed or don't work right.

Myelodysplastic syndromes result from something wrong in the spongy material inside the bones where blood cells are made, also called bone marrow. Most types have no known cause. Others are caused by cancer treatments or chemical exposure.

Symptoms may include shortness of breath, feeling very tired, easy bruising and a change in skin color.

Treatment may not be needed right away. Blood transfusions and medicines may help treat symptoms. Bone marrow transplants, also called stem cell transplants, and chemotherapy may be used in some people.