EZH2 and leukemia: Consistent with the broad overexpression pattern of HOXA9 in many leukemia cases, a wide variety of genetic alterations in leukemia contribute to HOXA9 dysregulation including MLL gene rearrangements (MLLr), NPM1 mutations, NUP98-fusions, EZH2 loss-of-function mutations, ASXL1 mutations, MOZ fusions and other chromosome alterations (Collins and Hess, 2016a; Jambon et al., 2019; De Braekeleer et al., 2014; Collins and Hess, 2016b).