Myelodysplastic syndromes (MDS) causes

MDS is caused by changes (mutations) in DNA within blood cells. For most people these changes are not inherited. Instead, they happen during a person’s lifetime.

We don’t know exactly why these genetic changes happen to some people and not to others. But we do know that there are some things that make people more likely to develop MDS. These are called risk factors.

While these things do slightly increase the risk of developing MDS, it can happen to anyone and it's not because of anything you have done.

For most people with MDS, no specific trigger or cause can be found.

MDS can be diagnosed at any age, but it’s more common as you get older. The typical age that people develop MDS is around 75 years old. About 9 in 10 people diagnosed with MDS are over 50. MDS is very rare in children and young adults.

People who are born male are twice as likely to develop MDS as people who are born female. We don’t know why.

Previous chemotherapy or radiotherapy treatment may damage the bone marrow and possibly cause MDS. This is called secondary or therapy-related MDS.

Very rarely, MDS can be inherited or may develop from another rare genetic disorder. If your doctor thinks your MDS may be inherited, they will refer you to a genetics service to discuss the chances of other family members having it. However, for most people, MDS is not passed down to children and is not an inherited genetic disease.

There are some related blood conditions which can increase the risk of developing MDS. These conditions include:

• clonal haematopoiesis of indeterminate significance (CHIP) – where you have genetic changes in otherwise healthy blood cells.
• idiopathic cytopenia of unknown significance (ICUS) – where you have low numbers of one or more types of blood cell for no obvious reason.
• clonal cytopenia of unknown significance (CCUS) – where you have genetic changes in your blood cells and low numbers of one or more types of blood cell for no obvious reason.

These conditions are not harmful and are not considered to be disorders or diseases. They are unlikely to make you feel unwell and don’t need any treatment. However, some people with these conditions do go on to develop MDS.

If you have CHIP, ICUS or CCUS your doctor may recommend regular blood tests to check if it is developing into MDS.

Long-term exposure to certain chemicals may increase the risk of MDS. One of these chemicals is benzene, which is found in tobacco smoke. It’s also used in some types of manufacturing, although there are now rules to stop people working with benzene being exposed to unsafe levels.