Update on myelodysplastic syndromes (MDS)

The myelodysplastic syndrome (SMD) represents a heterogeneous group of acquired and clonal hematologic disorders which affect the hemocytopoietic Stem Cell. They are characterized morphologically and clinically by ineffective hematopoiesis, progressive peripheral cytopenia, dysplasia in one or more cellular lineages, hypercellular and dysplasic bone marrow with variable percentage of blasts, in most cases; and evolutionary trend to acuted leukaemia. The transformation process in MDS is a multistep process causing the accumulation of genetic lesions involving genes that govern the mechanisms of proliferation and differentiation of hematopoietic precursors. In 1982, the French-American-British Hematology group (FAB) classified the SMD according to morphologic criteria in peripheral blood and bone marrow. Controversies and disagreements forced the WHO in 1999 to review the classification and to propose a new one. The WHO classification system introduces the importance not only of the morphologic characteristics, but also the relevance of clinical and cytogenetic evaluation, and the use of the inmunophenotype and the biological information to be able to define the different entities. The WHO classification correlates better with the prognosis, the therapeutic response, and the progression than the FAB classification. The International Prognostic Scoring System (IPSS) provides an improved method for evaluating prognosis in MDS. This classification system should prove useful for more precise design and analysis of therapeutic trials in this disease. With regard to treatment, present-day hope is placed in gene therapy. The development of new drugs directed against specific targets is the hope for the future.