In MDS, the bone marrow can't produce normal and healthy blood cells - red blood cell, white blood cell, Platelets. At the beginning people may feel no symptom at all. Later, they will feel constant tiredness(being lack of enough healthy red blood cell), unusual bleeding(being lack of enough healthy Platelets), bruises or red marks under the skin (again Platelets), short of breath(red blood cell). There are medications to improve the symptoms, but the only proven way to cure MDS is stem cell transplant.