KMT2A and acute myeloid leukemia: While the incidence and cellular origin of some ALL PFGs were examined relatively well [6,7,8,9,10,14], the most frequent AML PFGs, such as RUNX1-RUNX1T1, PML-RARα, and KMT2A-MLLT3, were only investigated sporadically, resulting in a wide range of variability, which was likely dependent on several factors including age, ethnicity and methodological issues [5].