Myelodysplastic syndromes (MDS) are a group of diseases which all affect, to a greater or lesser extent, the production of normal blood cells in the bone marrow. MDS is also sometimes referred to as myelodysplasia.
In MDS, abnormal bone marrow stem cells produce increased numbers of abnormal blood cells. These cells do not grow properly and often die prematurely. This results in lower numbers of normal red blood cells, white blood cells and platelets being produced. The blood cells that do survive are often of poor quality, are abnormal in appearance (dysplastic) and unable to function properly.
The release of these abnormal cells from the bone marrow into the blood stream is also defective. This means that 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 bruise more easily.
In approximately 15 per cent of cases, people with MDS have very low numbers of cells in their bone marrow. This is referred to as hypoplastic myelodysplasia. 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. People with mild disease are often found to have only anaemia, or they might have a lower than normal white blood cell or platelet count. In many cases they have few, if any, troubling symptoms from their disorder. In more severe cases, the lack of circulating blood cells is more pronounced, causing more symptoms. Some cases of MDS, approximately 30 per cent overall, have the potential to progress to acute myeloid leukaemia, and MDS is therefore a pre-leukaemic disease.