Myelodysplastic Syndromes (MDS)

Reviewed by health care specialists at UCSF Medical Center.\



Myelodysplastic syndromes (MDS) refer to a group of disorders in which the bone marrow stem cells — the primitive cells that give rise to all the different types of blood cells — are defective, causing an inadequate production of blood cells. Patients with MDS usually suffer from low counts of red blood cells, white blood cells or platelets, or a combination.

MDS was previously mischaracterized as “pre-leukemia” or “smoldering” leukemia because of its tendency to transform into acute myeloid leukemia.

The cause of MDS remains unknown. It occasionally develops after treatment with drugs or radiation for another medical condition, or after exposure to chemicals such as benzene or toluene. MDS occurs in older patients, often age 65 or older, which suggests that age may be the strongest risk factor for developing MDS.

Many kinds of treatments are available for MDS, including new medications and stem cell transplantation.

In myelodysplastic syndromes, the bone marrow is heavily infiltrated with MDS cells, which do a poor job of producing mature blood cells. Signs and symptoms include:

  • Low red blood cells counts, causing fatigue and shortness of breath
  • Abnormal white blood cells called neutrophils, which kill germs poorly, resulting in infection with bacteria, fungi or atypical mycobacteria (relatives of tuberculosis)
  • Low platelet counts, causing bleeding

The typical MDS patient is 60 to 80 years old with mild to modest anemia — low levels of red blood cells — in which iron, vitamin and endocrine gland deficiencies have been ruled out as a cause. The anemia usually progresses and reaches a point where the patient needs red blood cell transfusions.