Previous studies have shown that IKZF1 deletion is less frequent in BCP-ALL with recurrent chromosomal abnormalities 11,14–16, which is in agreement with our results showing that the frequency of IKZF1 deletion was lower in the TCF3-PBX1 fusion positive subgroup than in the other subgroups (Table 4). This evidence concerns the gene TCF3 and acute lymphoblastic leukemia.