The term Myelodysplastic Syndromes (MDS) refers to a group of related conditions that interfere with your body’s ability to make healthy blood cells. It’s a type of blood cancer.

Inside most of your larger bones is a fatty, spongy tissue called bone marrow. It’s here that “blank” stem cells transform into immature blood cells (called blasts).

They’re destined to become either a mature:

This process is called hematopoiesis.

When you have MDS, your bone marrow can still produce stem cells that become immature blood cells. However, many of these cells don’t develop into healthy, mature blood cells.

Some die before they leave your bone marrow. Others that do get into your blood stream may not function normally.

The result is low numbers of one or more types of blood cells (cytopenias) that are abnormally shaped (dysplastic).

The symptoms of MDS depend on the disease stage and the blood cell types that are affected.

MDS is a progressive disease. In its early stages, there are usually no symptoms. In fact, it’s often discovered accidentally when low blood cell counts are found when blood tests are done for another reason.

In later stages, low blood cell levels cause different symptoms depending on the type of cell involved. You may have several types of symptoms if more than one cell type is affected.

Red blood cells (RBCs)

RBCs transport oxygen throughout your body. A low RBC count is called anemia. It’s the most common cause of MDS symptoms, which may include:

White blood cells (WBCs)

WBCs help your body fight infections. Low WBC counts (neutropenia) are associated with symptoms of bacterial infections that vary depending on where the infection occurs. Often you’ll have a fever.

Common sites of infection include:

  • lung (pneumonia): cough and shortness of breath
  • urinary tract: painful urination and blood in your urine
  • sinuses: stuffy nose and pain over the sinuses in your face
  • skin (cellulitis): red warm areas that may drain pus


Platelets help your body form clots and bleeding. Symptoms of low platelet counts (thrombocytopenia) may include:

When blood cell counts get very low, complications can develop. They’re different for each blood cell type. Some examples are:

  • severe anemia: debilitating fatigue, trouble concentrating, confusion, inability to stand due to dizziness
  • severe neutropenia: recurrent and overwhelming life-threatening infections
  • severe thrombocytopenia: nose bleeds that won’t stop, bleeding gums, life-threatening internal bleeding such as from an ulcer that’s difficult to stop

Over time, MDS can transform into another blood cancer called acute myeloid leukemia (AML). According to the American Cancer Society, this happens in about one-third of the people who have MDS.

Often, the cause of MDS isn’t known. However, some things put you at higher risk of getting it including:

Having been exposed to certain chemicals and substances for a long time may also increase your risk. Some of these substances are:

  • tobacco smoke
  • pesticides
  • fertilizers
  • solvents such as benzene
  • heavy metals such as mercury and lead

The World Health Organization Classification of Myelodysplastic Syndromes is based on:

  • kind of blood cells affected
  • percentage of immature cells (blasts)
  • number of dysplastic (abnormally shaped) cells
  • presence of ring sideroblasts (an RBC that has extra iron collected in a ring in its center)
  • changes in chromosomes seen in bone marrow cells

MDS with unilineage dysplasia (MDS-UD)

  • low counts of one type of blood cell in the bloodstream
  • dysplastic cells of that blood cell type in the bone marrow
  • bone marrow contains less than 5 percent blasts

MDS with ring sideroblasts (MDS-RS)

  • low RBC counts in the bloodstream
  • dysplastic RBCs and 15 percent or more ring sideroblasts in the bone marrow
  • bone marrow contains less than 5 percent blasts
  • WBC and platelets are normal in number and shape

MDS with multilineage dysplasia (MDS-MD)

  • low counts of at least one type of blood cell in the bloodstream
  • at least 10 percent of two or more blood cell types are dysplastic in the bone marrow
  • bone marrow contains less than 5 percent blasts

MDS with excess blasts-1 (MDS-EB1)

  • low counts of at least one type of blood cell in the bloodstream
  • dysplastic cells of those blood cell types in the bone marrow
  • bone marrow contains 5 to 9 percent blasts

MDS with excess blasts-2 (MDS-EB2)

  • low counts of at least one type of blood cell in the bloodstream
  • dysplastic cells of those blood cell types and 10 to 19 percent blasts in the bone marrow
  • bloodstream contains 5 to 19 percent blasts

MDS, unclassified (MDS-U)

  • low counts of at least one type of blood cell in the bloodstream
  • less than 10 percent of those cell types are dysplastic in the bone marrow

MDS associated with isolated del(5q)

  • bone marrow cells have a chromosome change called del(5q), which means part of chromosome 5 is deleted
  • low RBC count in the bloodstream
  • platelet counts are normal or high in the bloodstream
  • bone marrow contains less than 5 percent blasts

When the bone marrow has 20 percent or more blasts, the diagnosis changes to AML. Normally, there’s less than 5 percent.

Three types of treatment are used for different reasons.

Supportive care

This is used to make you feel better, improve your symptoms, and help avoid complications from MDS.

  • transfusions: RBCs or platelets are given through your veins to improve very low RBC or platelet counts
  • antibiotics: used to treat or lower the risk for infections that may occur due to low WBC counts
  • growth factors: different growth factors can be given to help your bone marrow make WBCs, RBCs, and platelets more quickly to build up low blood counts

Treatment to slow MDS progression

Low-intensity chemotherapy

These are weaker drugs given at lower doses, which lowers the chance they will cause severe side effects.

  • azacytidine
  • decitabine

High-intensity chemotherapy

These are strong drugs given at high doses, so they’re more toxic. There’s a good chance they will cause severe side effects. These drugs are used to treat MDS that’s transformed into AML or before a stem cell transplant.

  • cytarabine
  • daunorubicin
  • idarubicin


Also called biologic therapy, immunotherapy helps your body’s defense systems fight disease. There are a number of different types.

Treatment for long-term remission

A stem cell transplant (previously called a bone marrow transplant) is the only available option that can cause long-term remission for MDS.

High-dose chemotherapy is given first to destroy the stem cells in your bone marrow. They are then replaced with healthy donor stem cells.

Complicated scoring systems are used to classify someone with MDS into a lower risk or higher risk group based on:

  • MDS subtype
  • number of blood cells types with low counts and their severity
  • percent of blasts in the bone marrow
  • presence of chromosome changes

The groups indicate how MDS might progress in that person if it’s not treated. They don’t tell you how it might respond to treatment.

Lower-risk MDS tends to progress slowly. It may be years before it causes severe symptoms, so it’s not treated aggressively.

Higher-risk MDS tends to progress rapidly and cause severe symptoms sooner. It’s also more likely to transform into AML, so it’s treated more aggressively.

Your healthcare provider will look at your risk group as well as a variety of other factors specific to you and your MDS to determine the treatment options that are best for you.

Several tests are used to diagnose and determine the subtype of MDS.

  • Complete blood count (CBC). This blood test shows the number of each type of blood cell. One or more types will be low if you have MDS.
  • Peripheral blood smear. For this test, a drop of your blood is put on a slide and examined under a microscope. It’s checked to determine the percentage of each type of blood cell and if any cells are dysplastic.
  • Bone marrow aspiration and biopsy. This test involves inserting a hollow needle into the center of your hip or breastbone. Liquid in the bone marrow is sucked out (aspirated) and a sample of the tissue is removed. The sample tissue is analyzed to determine the percentage of each blood cell type, the percentage of blasts, and to see if your bone marrow contains an abnormally high number of cells. A bone marrow biopsy is required to confirm the diagnosis of MDS.
  • Cytogenetic analysis. Theses tests use blood or bone marrow samples to look for changes or deletions in your chromosomes.

MDS is a type of blood cancer in which your bone marrow fails to produce adequate numbers of functioning blood cells. There are several different subtypes, and the condition may progress rapidly or slowly.

Chemotherapy can be used to slow the progression of MDS, but a stem cell transplant is needed to achieve long-term remission.

A variety of treatments are available for supportive care when symptoms such as anemia, bleeding, and recurrent infections occur.