In JMML, methylation in CpG islands was first analyzed in a European cohort of 86 patients, in which 14 candidate genes were selected based on their hypermethylation status in other cancer types (CALCA, CDKN1C, CDKN2B, DAPK1, MGMT, MLH1, RARB, RASSF1, SOCS1, and TP73) or their involvement in RAS signaling (BMP4, PAWR, RASA1, and RECK). The gene discussed is RASSF1; the disease is juvenile myelomonocytic leukemia.