ABSTRACT
The myelodysplastic syndromes (MDS) encompass a group of clonal stem cell disorders characterized by both bone marrow failure and a predilection to develop acute myeloid leukemia (AML). While the majority of patients with MDS are initially diagnosed with lower-grade disease, nearly two-thirds will ultimately succumb to complications of peripheral cytopenias or of progression to AML. The World Health Organization (WHO) classification (1) and the International Prognostic Scoring System (IPSS) (2) provide a useful framework for classification and risk stratification of individual patients, but these systems do not take into account the considerable clinical heterogeneity of MDS and their diverse biology. MDS per se represent many different conditions, probably not just a single disease. A marked variability exists among patients even within the same subtype or IPSS risk group.
