Retrospective analyses (by nested PCR) at the time point, when bone marrow sampled in the third week of life was MLL-rearrangement-negative by FISH, showed that the MLL-AF10 fusion transcript was already detectable back then, 4 months prior to the definitive diagnosis of AML in the bone marrow (Table 1). This evidence concerns the gene KMT2A and acute myeloid leukemia.