We thus sequenced genes coding for proteins involved in the RAS signaling pathway and a RAS mutation was found in four cases (~14%), including a codon 146 mutation in KRAS. In a recent study of CMML, mutations of KRAS and NRAS genes were found in 9 patients out of 32 [25]; two of the six KRAS mutations were in codon 146. This evidence concerns the gene KRAS and chronic myelomonocytic leukemia.