The AFF root symbol is derived from AF4/AF-4, standing for “ALL1-fused gene from chromosome 4” (ALL-1 is an alias for the KMT2A gene—also known as MLL1—because “AF4”, now approved as AFF1, was recurringly found in chromosomal translocations with KMT2A in acute lymphoid leukaemia [11]), combined with the F from FMR2. The gene discussed is KMT2A; the disease is acute lymphoblastic leukemia.