The main immunophenotypic features distinguishing low-risk MDS from reactive cytopenias were the increase of CD34+ cells, especially in the presence of normal blast counts in cytology, increase in CD34+/CD117+/CD13+ cells, decrease in B-cell precursors, and aberrant co-expressions in CD34+ cells (CD7 or CD56 or decrease in CD13). This evidence concerns the gene ANPEP and myelodysplastic syndrome.