Myelodysplastic syndromes (MDS)

Myelodysplastic syndromes (MDS) are a group of diseases where the production of blood cells by the bone marrow is disrupted.

The myelodysplastic syndromes (MDS) are a group of diseases in which the production of blood cells by the bone marrow is disrupted. The bone marrow in MDS is usually more active than normal but there are fewer blood cells in the circulation. This is because most of the cells being produced in the bone marrow are poor quality (dysplastic) and are destroyed before they leave the bone marrow. This is the distinctive feature of MDS – the combination of overactive marrow with low blood cell counts. In about one third of patients with MDS, the disease transforms into acute myeloid leukaemia (AML) – this can occur within months or up to a few years later. MDS is very rare in children and this information is about adult MDS only.

What causes MDS?

For the vast majority of MDS patients, it is not known what caused the disease. However, there are a number of factors that can increase your chances of developing MDS:

  • Age – MDS can happen at any age, but is less common in children and more than nine out of 10 patients are aged 50 or over. The average age at which people are diagnosed is about 74y.
  • Sex – men are more likely to develop MDS than women.
  • Treatment for a previous cancer – having had some types of chemotherapy or radiation treatment for cancer may increase the risk of MDS. It is important to understand that the benefit of treatment outweighs the risk of MDS.

MDS does not normally run in families but there are rare types of MDS that do.

No evidence exists to suggest that any infection increases the risk of MDS and it cannot be passed to other people.

Signs and symptoms of MDS

About one in five (20%) MDS patients have no signs or symptoms and are often diagnosed by chance as a result of a routine blood test. Low levels of blood cells cause the main symptoms of MDS. These symptoms include:

  • Feeling tired, weak and breathless
  • Frequent infections
  • Bruising and bleeding more easily as a result of reduced platelets
  • Night sweats

You may not experience any of these symptoms at all. It is also worth remembering that these symptoms are often related to other conditions and do not always indicate MDS.

Types of MDS

There are several classification systems for MDS, which are based on the appearance of the bone marrow and the blood cells. The newest classification system was developed by the World Health Organisation (WHO) in 2016.

There are six types of adult MDS in the WHO 2016 system which are:

  1. MDS with single lineage dysplasia
  2. MDS with ring sideroblasts
  3. MDS associated with isolated deletion 5q
  4. MDS with multilineage dysplasia
  5. MDS with excess blasts
  6. MDS Unclassifiable

MDS with single dysplasia

Single lineage means that only the bone marrow cells that are destined to make one type of blood cell (either a red cell, neutrophil or platelet) looks abnormal (dysplasia).

MDS with multilineage dysplasia

Multilineage means that more than one type of bone marrow cell looks abnormal under the microscope (dysplasia). At least one blood cell type has low numbers.

MDS with ring sideroblasts

This is the same as MDS with single lineage or multi lineage dysplasia but there are red blood cells with ring shaped deposits of iron in them. These abnormal red cells are called ring sideroblasts.

MDS with isolated deletion 5q

This is like MDS with single lineage or multilineage dysplasia but there is part of chromosome five missing (deletion) and with no other abnormalities of chromosomes in the affected cells. There is often a raised platelet count. This form is more often seen in female patients.

Refractory anaemia with excess blasts

This is the same as refractory anaemia but there are at least 5% blasts (very immature blood-forming cells) in the marrow but fewer than 20%.

If there are more than 20% blasts then it is classified as acute myeloid leukaemia. There is dysplasia in most cases.

MDS Unclassifiable

There are some features in the blood and bone marrow samples which are seen in MDS but it does not fit any of the above categories.

Prognostic Scoring System

There is an International Prognostic Scoring System (IPSS) which has been developed to help doctors to predict how likely MDS is to progress to acute myeloid leukaemia (AML). The IPSS is used to help doctors decide what treatment to recommend.

The IPSS Score is determined by adding the individual scores for the percentage of blasts in bone marrow and for the cytogenetic and blood test findings, and is used to assess the clinical outcome for the MDS patient.

A newer version is called the Revised IPSS (IPSS-R) and includes five risk groups, which are:

  1. Very Low: IPSS-R score 0 to 1.5
  2. Low: IPSS-R score more than 1.5 to 3
  3. Intermediate: IPSS-R score more than 3 to 4.5
  4. High: IPSS-R score more than 4.5 to 6
  5. Very: IPSS-R score greater than 6

Diagnosis of MDS

MDS is diagnosed from blood tests and bone marrow examinations. The initial step in making a diagnosis of MDS is to have a full blood count (FBC). When the microscopic appearance of the blood cells suggests a diagnosis of MDS the doctor will then take a full clinical history of the patient and will take a sample of bone marrow to confirm the diagnosis. A bone marrow examination can reveal abnormalities in the cells of the marrow and also chromosomal abnormalities, such as missing or extra chromosomes. Molecular tests for gene mutations are now also done in some laboratories but how they are used for routine care is not yet clear. These tests provide additional information that can help in establishing the diagnosis. According to the British Committee for Standards in Haematology (BCSH) guidelines: “the diagnoses and classification of MDS remains dependent on the morphological examination” (how cells appear under the microscope).

Treatment of MDS

Not all patients with MDS will receive active treatment straightaway, but will have regular check-ups. This is referred to as active monitoring or ‘watch and wait’. The treatment that is most appropriate for you will depend on the type of MDS you have, the IPSS-R risk group you’re in, your personal preferences and your general health. Most people with MDS have treatment at some point to control and improve the symptoms caused by low blood counts. This is called supportive treatment. Sometimes this may be the only treatment that is needed if you’re in the low-risk category. The only treatment that is considered to be a cure is a donor stem cell transplant, although only a small minority of patients will be candidates for this type of treatment.

Treatment options

There are many different treatment options available if you have MDS. These include:

  • Transfusions – blood and/or platelet
  • Growth factors
  • Chemotherapy
  • Hypomethylating agents
  • Stem cell transplants
  • Novel treatments – there are several new drugs being developed for treatment of MDS

Questions to ask your medical team about myelodysplastic syndromes

We understand going through a blood cancer journey can be difficult. It may help to talk to a close friend or relative about how you are feeling. Here are a list of questions that may be useful to ask your medical team.

  • How can you tell if I have MDS?
  • What does that mean for me?
  • What tests will I need to have?
  • What will the tests show?
  • How long will the results take?
  • What sort of treatment will I need?
  • How long will my treatment last?
  • What happens if the treatment doesn’t work?
  • Can any treatments cure my MDS?
  • Will I need to be off work/college?
  • What are the chances of my MDS coming back?
  • Where can I get help dealing with my feelings?

Further downloads

We have free patient information available for MDS patients.

You can download our MDS booklet on our information pages here.

Alternatively, you can have the information delivered free of charge by requesting it through our resources page. 

Further support for MDS

MDS-UK is a dedicated support charity for MDS patients. You can find out more information on MDS on their website at