Whereas, fusions involving KMT2A, CBFA2T3, or MNX1 are molecular hallmarks of AML affecting infants and early childhood (<3 years), those affecting the core binding factor (RUNX1 and CBFB) or the retinoid acid receptor (RARA) occur at any age but peak in children (3–14 years) or even in young adults (15–39 years). The gene discussed is MNX1; the disease is acute myeloid leukemia.