Myelodysplastic syndromes (MDS) are a group of cancer conditions caused by abnormal blood cells forming in the bone marrow.
In MDS, the bone marrow has trouble making new blood cells. Many of the cells are defective, and they die earlier or are eliminated by the body's immune system. This can leave the body without enough normal blood cells.
Early stages of MDS are often without symptoms, but over time, a person with MDS may experience: