ABSTRACT
The myelodysplastic syndromes (MDS) comprise a heterogenous group of clonal hematopoietic stem cell disorders characterized by progressive cytopenia and qualitative abnormalities in the erythroid, granulocytic, and megakaryocytic series, and are associated with frequent evolution to acute myeloid leukemia (AML). Augmented apoptosis, leading to ineffective hematopoiesis and peripheral cytopenias, has been observed (1), but the precise nature of the genetic lesions that lead to clonal hematopoiesis and leukemic transformation is unknown. The clonality of MDS has been confirmed by the high number of nonrandom cytogenetic abnormalities (2) and by X-chromosome inactivation analysis (3). Numerous therapeutic modalities have been instituted to eliminate the dysplastic clone or induce clonal differentiation. The identification of risk factors for disease progression and the establishment of prognostic indicators for individual patients has been invaluable in the approach to patient management.
