Myelodysplastic syndromes (MDS) are a group of related conditions that interfere with the body’s ability to make healthy blood cells. They are a type of blood cancer.

In the early stages of myelodysplastic syndromes (MDS), there may be no symptoms. But, in time, a person may start to experience fatigue due to anemia, easy bruising and bleeding, and frequent infections.

Often, there is no clear cause, but exposure to certain chemicals — for instance, during chemotherapy or when working with solvents — may increase the risk.

Treatment is with medications or stem cell therapy, and the outlook depends on the type of MDS.

Inside most of the 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 a mature red blood cell (RBC), platelet, or white blood cell (WBC). This process is called hematopoiesis.

If 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 blood cells die before they leave your bone marrow. Others that do get into your bloodstream may not function normally.

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

Types of myelodysplastic syndromes

The types of myelodysplastic syndromes include:

  • MDS with single lineage dysplasia (MDS-SLD)
  • MDS with ring sideroblasts (MDS-RS)
  • MDS with multilinear dysplasia (MDS-MLD)
  • MDS, unclassified (MDS-U)
  • MDS associated with isolated del(5q)
  • MDS with excess blasts-1 (MDS-EB1)
  • MDS with excess blasts-2 (MDS-EB2)

The World Health Organization (WHO)’s Classification of Myelodysplastic Syndromes takes into account:

  • 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

The percentage of blasts in bone marrow and blood differentiates MDS EB1 and EB2.

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

MDS is a progressive disease. In the early stages, you may not experience any symptoms. Medical professionals may detect MDS when noticing low blood cell counts in blood tests they order 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 it affects more than one cell type.

Symptoms of myelodysplastic syndromes can include:

Often, the cause of MDS isn’t clear, but some factors may increase the risk. These include:

  • being over the age of 50 years
  • prior treatment with chemotherapy
  • prior treatment with radiation therapy
  • having other blood conditions, such as:
    • clonal cytopenia of unknown significance (CCUS)
    • clonal haematopoiesis of indeterminate significance (CHIP)
    • idiopathic cytopenia of unknown significance (ICUS)
  • exposure to certain chemicals, such as tobacco smoke

Several tests can help diagnose and determine the subtype of MDS. These include the following:

  • Complete blood count (CBC): A CBC shows the number of each type of blood cell. One or more types will be low if you have MDS.
  • Bone marrow aspiration and biopsy: A bone marrow aspiration and biopsy involves inserting a hollow needle into the center of the hip or breastbone to remove samples from the bone marrow. It can confirm or rule out MDS.
  • Cytogenetic analysis: These tests use blood or bone marrow samples to check for genetic changes.

Treatments can help directly address MDS and manage symptoms.

Possible treatments for MDS include:

  • chemotherapy
  • immunosuppressants
  • stem cell transplant
  • targeted therapy
  • immunotherapy
  • blood transfusions
  • antibiotics for an infection

Your doctor will work with you to create a suitable treatment plan based on individual circumstances.

Over time, MDS can transform into another blood cancer called acute myeloid leukemia (AML).

According to the American Cancer Society, about 1 in 3 people with MDS develop AML.

When blood cell counts get very low, complications can also develop. They’re different for each blood cell type.

Some examples are:

  • Severe anemia: This can lead to severe fatigue, trouble concentrating, confusion, and difficulty standing due to dizziness.
  • Severe neutropenia: This can lead to recurrent infections and a risk of sepsis.
  • Severe thrombocytopenia: This can result in nosebleeds that won’t stop, bleeding gums, and internal bleeding, such as from an ulcer, that’s difficult to stop.

Doctors use a complex scoring system to estimate an individual’s outlook with MDS. This will depend on the type of MDS they have.

The system classifies the person’s condition into a lower-risk or higher-risk group based on:

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

The groups indicate how MDS might progress if the individual doesn’t have treatment. 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 treatment is not aggressive.

Higher-risk MDS tends to progress rapidly, and severe symptoms appear sooner. It’s also more likely to transform into AML, so it needs more aggressive treatment.

A doctor will look at your risk group as well as a variety of other factors to determine the best treatment options for you.

MDS is a group of conditions that are a type of blood cancer. Around one third of people with MDS will develop acute myeloid leukemia (AML).

A stem cell transplant is usually the only potential cure for MDS. It can come with a risk of serious complications, so speak with your doctor about whether this treatment may be an option for you.

If a transplant is not an option, there are other treatments that can prolong a person’s life and help improve their comfort and quality of life.

It’s not clear what the main cause of MDS is, but prior cancer treatment and exposure to certain chemicals may increase the risk. It does not usually run in families.

As the exact causes of MDS are unclear, it may not be possible to completely prevent MDS. However, avoiding risk factors such as cigarette smoke may help to reduce the risk.

Myelodysplastic syndromes (MDS) are a type of blood cancer in which the bone marrow does not produce adequate numbers of functioning blood cells. There are several different subtypes, and the condition may progress rapidly or slowly.

You may not experience symptoms in the beginning. When symptoms do develop, they can include fatigue, pale skin, weakness, frequent infections, easy bruising or bleeding, dizziness, and shortness of breath.

Blood tests and a bone marrow aspiration and biopsy can help diagnose the condition. Chemotherapy can help slow the progression of MDS, but a stem cell transplant can achieve longer-term remission.