Myelodysplastic syndromes (MDS) represent a group of closely related diseases arising from impaired hematopoietic stem cells in the bone marrow. These stem cells would otherwise differentiate to form red blood cells, white blood cells or platelets, and patients with MDS may initially present with anemia, neutropenia, thrombocytopenia or other hematological symptoms. Visually, the cells may appear abnormal, or dysplastic.
Etiology of MDS is unknown, but exposure to high doses of radiation or chemotherapy is believed to play a role. According to National Cancer Institute, MDS incidence is about 13,000 per year or 4.4 to 4.6 cases per 100,000 people in the US. Median age at diagnosis is approximately 70, and over 80 percent of patients are over 60 years old. About 50 percent of patients have a cytogenetic abnormality, such as a deletion of all or part of chromosome 5 or 7, or trisomy 8. About 30 percent of MDS cases progress to AML, according to American Cancer Society.