KMT2A and acute myeloid leukemia: <i>Background</i>: Chromosomal rearrangements involving lysine methyltransferase 2A (KMT2A) define a genetically distinct subset of acute myeloid leukemia (AML) in 10% of cases in adult patients; the frequency of <i>KMT2A-r</i> is higher in pediatric AML.