Myelodysplastic syndromes (MDS) are chronic myeloid hemopathies characterized by ineffective hematopoiesis (with peripheral cytopenias) and which contrast with a marrow of normal richness. MDS is considered one of the four most common blood diseases. The incidence is estimated at 4,059 cases / year in 2012 with an average age of 78 years in men and 81 years in women (INCA report, Cancers in France in 2015). The incidence increases with lengthening of the lifespan. The main risk of MDS is transformation to acute leukemia in 30 to 40% of cases. Treatment options depend on clinical, hematologic and chromosomal abnormalities. The prognosis is considered to be at low or high risk of developing acute leukemia. This distinction will therefore have an impact on the therapeutic solution (s). MDS exhibit clinical, morphological and genetic heterogeneity. It is therefore necessary to form subgroups of patients to better understand the physiopathogenesis of this pathology. The constitution of a biocollection will make it possible to search for clinical and biological prognostic markers in order to identify patients progressing to acute myeloid leukemia.