Myelodysplastic syndrome

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What is myelodysplastic syndrome (MDS)?

Myelodysplastic syndrome (MDS) is a rare type of blood cancer whereby the bone marrow does not produce enough healthy blood cells, sometimes also referred to as myelodysplasia or bone marrow failure.

The bone marrow is the spongy material inside the bones where new blood cells are produced. The normal process of blood cell production starts with a stem cell, which is an immature cell that can develop into all types of blood cell. When the stem cell divides, it can either produce more stem cells or produce immature blast cells with the potential to further develop and mature.

The immature blast cells can mature and develop in the bone marrow to become the three types of blood cells: red blood cells, white blood cells, or platelets. All blood cells have an important function.

  • Red blood cells (also called erythrocytes) – carry oxygen around the body to organs and tissues
  • White blood cells (also called leukocytes) – protect against illness & disease by fighting infections
  • Platelets (also called thrombocytes) – help blood clot to prevent bruising and bleeding.

Myelodysplastic syndrome symptoms 

Symptoms of myelodysplastic syndrome are likely to vary and be dependent on the type of MDS. The most common symptoms of MDS* can include: 

  • Bruising and bleeding easily, which are caused by a low level of platelets 
  • Frequent infections, which are caused by a low level of white blood cells  
  • Fatigue and breathlessness, which can be caused by a low level of red blood cells 

Some people may have no symptoms of MDS. Patients are most likely to find out their diagnosis through a blood test.  

If you have any concerns about symptoms of MDS, make sure to talk to your doctor, who will be able to provide more information.

Myelodysplastic syndrome facts

  • Dysplasia is the terminology to describe cells in the bone marrow that look abnormal and have a different shape compared to normal.
  • MDS is most commonly diagnosed in adults over the age of 70, but younger people can be affected.
  • Approximately 30% of patients with MDS can develop acute myeloid leukaemia (AML).
  • MDS is slightly more common in men than women.


In MDS, the bone marrow fails to produce healthy blood cells and instead makes abnormal cells that are unable to function normally. There are many different types of MDS classified based upon the type or types of blood cell affected and the extent of immature non-functioning blood cells present.

All types of blood cell may be affected which can cause a range of symptoms depending upon the cells affected. The severity of symptoms may vary depending on the type of MDS, from no symptoms to severe symptoms. For many patients, symptoms may be mild at first but may worsen over time.

There are a number of types of MDS, which are based on genetics and morphology (how the calls appear).

How does MDS develop?

MDS develops when something goes wrong with the normal process of healthy blood cell production in the bone marrow. All blood cells start off as stem cells which, in response to the need for more blood cells, develop and mature into healthy fully functioning blood cells which then migrate into the blood stream.

MDS occurs when stem cells die in the bone marrow, or do not divide or the blast cells do not mature and remain in the bone marrow. The result is that the immature cells may crowd out the bone marrow leaving less room for the production of new healthy blood cells. The result is fewer healthy functioning blood cells.

Failure to produce sufficient health blood cells may result in low blood cell counts often referred to as cytopenias. Cytopenias are a hallmark feature of MDS and are responsible for many of the symptoms that MDS patients experience such as repeated infections, anaemia, spontaneous bleeding, or easy bruising. In addition to reduced numbers of blood cells, any mature blood cells circulating in the blood may not function properly. Reduced blood count and non-functioning blood cells can have a significant effect upon the health of a person diagnosed with MDS.

The bone marrow’s failure to produce healthy blood cells may be a gradual process and therefore MDS may not be a life-threatening disease. There are many different types of MDS, some types can remain mild for years and others may be more serious.

Does MDS progress into acute myeloid leukaemia (AML)?

Many people diagnosed with MDS will have a mild form of the disease which may remain mild for many years. However, some people with MDS may go on to develop acute myeloid leukaemia (AML), which is a cancer of the white blood cells. This is often known as transformation; it can take months or several years before transformation can take place.

The risk of MDS developing into AML depends on the type of MDS and the extent of the disease e.g., the number of normal versus abnormal blood cells. In MDS, the bone marrow may have many immature abnormal cells called blasts. In some MDS patients the number of blasts may increase with time, AML is defined as having more than 20% blast cells.

Treatment for myelodysplastic syndrome

Treatment* will be dependent on the type of MDS and if the patient is at risk of developing AML or other health conditions. MDS treatment is aimed at getting the number and type of blood cells in the bloodstream back to a safe level. 

Your doctor will assess which treatments are best for you, which could include: 

  • No treatment but regular check ups to assess levels of blood cells. This usually takes place when the type of MDS is classified as low risk 
  • Antibiotics to treat infections 
  • Growth factors to encourage the bone marrow to make more blood cells 
  • Blood transfusions to regulate red blood cells or platelets 
  • A stem cell transplant 
  • Immunosuppression treatment 
  • Chemotherapy  

If you have any concerns about what MDS treatment is right for you, make sure to talk to your doctor who will be able to provide more information and resources. 

Acute myeloid leukaemia (AML)

Acute myeloid leukaemia

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