KMT2A and myelodysplastic syndrome: With rearrangements found in ~40% of therapy-related acute leukemia/myelodsyplastic syndrome (t-AL/MDS), MLL is the most frequently rearranged gene in t-AL (Shivakumar et al., 2008; Pullarkat et al., 2009; Shim et al., 2010; Abdulwahab et al., 2012; Cowell and Austin, 2012).