We analyzed aberrant DNA methylation at the BMP4 promoter in leukemic cells from 111 JMML patients and nine children without hematological malignancy as controls, building on previous investigations which had demonstrated a robust correlation between clinical parameters indicative of poor prognosis in JMML and global DNA hypermethylation across numerous CpG sites [8–10, 12]. Here, BMP4 is linked to juvenile myelomonocytic leukemia.