IKZF1 and leukemia: The deletion of exons 4–7, lacking the ability to bind DNA, was a negative domain and thus led to leukemia (Mullighan et al., 2008; Iacobucci et al., 2009; Chiaretti et al., 2016), which was the most common deletion pattern of IKZF1 in our cohort (36%), consistent with results in Germany, Japan, Sweden and the US and different from results in Mexico, where the deletion of exon 1 (85%) occurred most frequently (Ayon-Perez et al., 2019).