IKZF1 and acute lymphoblastic leukemia: The most common IKZF1 alteration associated with Ph-like (and JAK2r) ALL is a deletion of IKZF1 exons 3-6, encoding the dominant negative IK6 isoform of IKAROS, which lacks the N-terminal DNA binding domain (Roberts et al., 2014a; Tran et al., 2018; Shiraz et al., 2020).