Myelodysplastic syndromes (MDS) are a group of blood disorders that occur when the bone marrow does not produce enough healthy blood cells. This can lead to anemia, leukopenia or thrombocytopenia, and is often caused by damage to the DNA in the stem cells responsible for producing blood cells. MDS can be classified into different types based on the severity of the condition and the number of affected blood cell lines. Treatment options may include chemotherapy, radiation therapy or a bone marrow transplant depending on the stage and progression of the disease.