HLA class I expression was normally expressed in CD34+ blasts and during myeloid differentiation in MDS patients; however, the copy-neutral loss of heterozygosity in the HLA region appeared to favor MDS progression to AML and selective downregulation of HLA class I enhanced KIR AA protection against different leukemia types [18–21]. This evidence concerns the gene KIR3DL1 and myelodysplastic syndrome.