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About myelodysplastic syndromes (MDS)

Find out about myelodysplastic syndromes, the signs and symptoms and how they are diagnosed. 

What myelodysplastic syndromes are

Myelodysplastic syndromes are also called myelodysplasia or MDS for short. This group of conditions causes a drop in numbers of normal blood cells. 

MDS blood cells have changes in them that make them develop abnormal cells. They might not need treatment for many years, but some go on to develop into acute myeloid leukaemia (AML). This means that they are cancer but how they progress will depend on the type that you have and the risk of them going on to develop into AML.

Myelodysplastic syndromes get their name from myelo, meaning bone marrow, and dysplasia, meaning abnormal growth.

The bone marrow is the soft inner part of our bones that makes blood cells. All blood cells start from the same type of cell called a stem cell. The stem cell makes immature blood cells. The immature cells go through various stages of development before they are released into the blood as fully developed blood cells.

These include:

  • red blood cells to carry oxygen around our bodies
  • white blood cells to fight infection
  • platelets to help the blood clot
Diagram showing how blood cells are made
The diagram shows how the various different types of cells develop from a single blood stem cell.

With myelodysplastic syndromes the bone marrow doesn't make enough normal blood cells. The blood cells it does make are not fully developed and not able to work normally.

These abnormal blood cells then either stay in the bone marrow or are destroyed before they get into the bloodstream. As the condition develops, the bone marrow becomes full. The immature blood cells then spill out into the bloodstream.

The low numbers of normal blood cells in the bloodstream eventually cause symptoms. The symptoms may be difficult to control.

Myelodysplastic syndromes are most common in people between the ages of 65 to 70. Only 1 in 5 people (20%) with MDS are younger than 50.

Causes of MDS

We don't know what causes most cases of MDS. You may hear this called primary MDS.

We do know of some risk factors that makes the risk of developing MDS more likely.

One of these is exposure to the chemical benzene. People are most likely to come into contact with benzene through their work. It is used in the rubber industry and is one of the chemicals in petrol. There is also benzene in traffic pollution, although levels are too low to make this a likely risk factor. It is also in cigarette smoke.

More rarely MDS is caused by radiotherapy or chemotherapy treatment for cancer. This is called secondary or treatment related MDS.

Signs and symptoms of MDS

Some people with a myelodysplastic syndrome don’t have any symptoms at all. Their MDS is picked up on a routine blood test for something else.

For most people, symptoms tend to be mild at first and get worse slowly. The symptoms are caused by a drop in the number of blood cells and could include:

  • tiredness and sometimes breathlessness because of a low red blood cell count (anaemia)
  • frequent infections because of a low white blood cell count
  • bleeding (such as nosebleeds) or bruising easily because of a low platelet count

Diagnosis of MDS

To diagnose MDS, you have blood tests and bone marrow tests.

The blood tests show how many normal blood cells and how many abnormal or immature cells you have.

For a bone marrow test, a doctor or specialist nurse removes a sample of bone marrow to examine it closely. This is usually taken from your hip. Bone marrow is the soft area at the centre of some of our bones. You usually have the test in the outpatient department of the hospital. 

As well as looking at the bone marrow cells, your doctor tests for abnormalities in your chromosomes. Chromosomes contain the genetic material inside the cells. These tests are called cytogenetics (pronounced sigh-toe gen-et-ics).


There are many different types of myelodysplastic syndromes

Last reviewed: 
07 Sep 2017
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