What is MDS?
Myelodysplastic syndromes (MDS) are a group of blood cancers which affect the production of normal blood cells in the bone marrow. MDS is sometimes referred to as myelodysplasia.
In MDS, the bone marrow makes unhealthy ‘dysplastic’ blood stem cells . This means they are abnormally formed and don’t grow or work as they should. Many of these abnormal blood cells die in the bone marrow or when they get to the bloodstream, but this results in lower numbers of functioning red blood cells, white blood cells and platelets.
People with MDS often have a very active bone marrow but a low number of circulating blood cells. Without enough red blood cells, white blood cells and platelets you can become fatigued, more susceptible to infections, and can bleed and/or bruise more easily.
There are different types of MDS and the disease can vary in its severity and in the degree to which normal blood cell production is affected.
There is a small group of people with MDS (10-15%) who have very low numbers of blood cells in their bone marrow. This is called hypodysplastic syndrome (MDS-h) or hypoplastic myelodysplasia.
About 30% of people with MDS progress to acute myeloid leukaemia (AML). This is diagnosed by the percentage of immature blood stem cells (blast cells) they have in the bone marrow. Someone with a healthy bone marrow would have between 2-5% of blast cells in their bone marrow. Someone with MDS will have more than 5% and someone with AML will have more than 20% of blast cells in their bone marrow.
