These cells, present at substantially higher numbers in MDS patients than controls, exhibited a DNA promoter CpG hypermethylation phenotype across four genes frequently hypermethylated in MDS blood cells (CDKN2B, DAPK1, CDH1, and SOCS1); none were methylated in ECFCs from any of 14 healthy individuals. Here, DAPK1 is linked to myelodysplastic syndrome.