MDS: About MDS

Myelodysplastic syndromes (MDS) are a group of diseases affecting the blood and bone marrow, which is the soft, spongy area at the center of the bones.

The marrow works like a factory, making stem cells that have the potential to create many other cells. This critical function is known as hematopoeisis—from the Greek, hemato meaning “blood,” and poeisis (po-ay-sis), meaning “making”.

Stem cells develop into red blood cells that carry oxygen, platelets that prevent bleeding, and white blood cells that fight infection. 

In MDS, however, stem cells make more than normal number of blood cells. Some of them die prematurely and never make it out of the marrow to blood while others do not mature properly. As a result, the entire blood production process is interrupted and thrown off track.

MDS is generally divided into two types: low risk or high risk. With high-risk MDS, the number of immature white blood cells (known as blasts or dysplastic cells) in the bone marrow can increase, crowding out the healthy cells and eventually leading to acute myeloid leukemia (AML). As a result, MDS is sometimes referred to as a “pre-leukemia” or “smoldering leukemia.” In roughly 30 percent of patients, it progresses to AML.

In both forms of MDS, the number of immature white blood cells (known as blasts or dysplastic cells) increases in the bone marrow, crowding out the healthy cells.

As the number of oxygen-carrying red blood cells decline, patients may develop anemia, appearing pale, tired or short of breath.  A decline in platelets that normally help the blood clot may lead to easy bruising or bleeding. A decline in white blood cells puts patients at increased risk for infections that can sometimes be life-threatening.  

The impact of MDS on a patient’s life varies considerably. For many, it can turn into a full-blown leukemia or cancer of the blood. For others, this diseases progresses fairly slowly.