KMT2A and acute myeloid leukemia: Unlike in AML, where KMT2A fusions and partial tandem duplications (PTD) are frequent, FISH (fluorescence in situ hybridization) and WES analyses in 500 CMML samples identified only a single patient with a MLLT3-KMT2A fusion (Fig. 6B), without any KMT2A mutations or PTD22,23.