The lysine methyltransferase family 2 (KMT2) family, commonly known as MLL (Mixed Lineage Leukemia), comprises a highly conserved group of histone methyltransferases that are responsible for mono-, di-, and tri-methylation at histone three lysine 4 (H3K4me1/2/3, respectively) through their conserved SET domain (Su(var)3–9, Enhancer of zester and Trithorax) (2, 3, 4). Here, KMT2A is linked to leukemia.