[Myelodysplastic syndromes--clinical and biological features].

The myelodysplastic syndromes comprise a heterogeneous group of hematopoietic disorders characterized by peripheral cytopenia, and ineffective and dysplastic hematopoiesis. Patients are predominantly aged, and often develop acute non-lymphocytic leukemia. Bone marrow failure, notably infection and bleeding, is the most common cause of death. Our understanding of the biology of the myelodysplastic syndromes is limited and thus reduces the efficacy and specificity of therapeutic intervention. Available evidence, however, suggests that the myelodysplastic syndromes arise from hematopoietic stem cells. The emergence and progression of the myelodysplastic clone have been reviewed in the light of the multistep theory of human carcinogenesis.