Myelodysplastic syndromes (MDS) are a heterogeneous group of hematological malignancies characterized by cytopenia(s), dysplasia in one or more major myeloid cell lines and progression to acute leukemia. Morphological analysis of peripheral blood (PB) and bone marrow (BM) remains the cornerstone of the diagnosis. Preliminary studies identified Flow Cytometry (FC) markers on red cells, platelets and circulating leukocytes that are expressed differently in MDS and in controls. However, these markers have been evaluated separately. The investigators propose to test in a large cohort of patients these markers, and to combine the most relevant ones in order to define a PB FC-based diagnosis score that would discriminate between MDS and non-clonal hematopoiesis and would avoid useless bone marrow samples in elderly

Inclusion Criteria:

1. Patient who have been orally informed, and given a short written information notice about the study
2. Adult patient>18 years
3. For whom a blood sample analysis is routinely prescribed
4. Presenting cytopenia on at least one lineage according to the 2016 WHO classification (Hemoglobin level<100 g/L and/or platelets <150 G/L and/or Neutrophils<1G/L).
5. For whom a bone marrow analysis for morphology assessment and cytogenetics have to be performed, because of suspicion of MDS.t The results of this bone marrow evaluation will classify the patients in Group 1 (MDS diagnosis) and Group 2 (no MDS according to the 2016 WHO criteria), defining the two populations of this validation cohort for whom the FC score will be calculated.

Exclusion Criteria:

1. Transfused patients (less than 3 months) in RBC or platelets units

MDS