These include mutations in genes known to cooperate with CBF-rearrangements [e.g. NRAS (n = 6), KRAS (n = 4), FLT3 (n = 2), KIT (n = 3), ZBTB7A (n = 2)] as well as in genes, which have not been described to be mutated in CBF leukemia so far (e.g. ZFHX4, NFE2, HERC1). This evidence concerns the gene NRAS and leukemia.