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Myelodysplastic Syndrome

< Blood and Bone Disease

Myelodysplastic Syndrome

About Myelodysplastic Syndrome

Myelodysplastic syndromes are a group of cancers in which immature blood cells in the bone marrow do not mature or become healthy blood cells.

In a healthy person, the bone marrow makes blood stem cells (immature cells) that become mature blood cells over time.

A blood stem cell may become a lymphoid stem cell or a myeloid stem cell. A lymphoid stem cell becomes a white blood cell. A myeloid stem cell becomes one of three types of mature blood cells:

  • Red blood cells that carry oxygen and other substances to all tissues of the body.
  • Platelets that form blood clots to stop bleeding.
  • White blood cells that fight infection and disease.

In a patient with a myelodysplastic syndrome, the blood stem cells (immature cells) do not become mature red blood cells, white blood cells, or platelets in the bone marrow. These immature blood cells, called blasts, do not work the way they should and either die in the bone marrow or soon after they go into the blood. This leaves less room for healthy white blood cells, red blood cells, and platelets to form in the bone marrow. When there are fewer healthy blood cells, infection, anemia, or easy bleeding may occur.


Signs and symptoms of a myelodysplastic syndrome include shortness of breath and feeling tired.

Myelodysplastic syndromes often do not cause early signs or symptoms. They may be found during a routine blood test. Signs and symptoms may be caused by myelodysplastic syndromes or by other conditions. Check with your doctor if you have any of the following:

  • Shortness of breath.
  • Weakness or feeling tired.
  • Having skin that is paler than usual.
  • Easy bruising or bleeding.
  • Petechiae (flat, pinpoint spots under the skin caused by bleeding).

Risk Factors

Age and past treatment with chemotherapy or radiation therapy affect the risk of a myelodysplastic syndrome. Risk factors for myelodysplastic syndromes include the following:

  • Past treatment with chemotherapy or radiation therapy for cancer.
  • Being exposed to certain chemicals, including tobacco smoke, pesticides, fertilizers, and solvents such as benzene.
  • Being exposed to heavy metals, such as mercury or lead.