Deletion of IKZF1 gene, which codes for IKAROS protein, has been linked to high expression of RAG1 in adult B-ALL, hypothesizing the role of aberrant RAG expression, in absence of IKAROS, as a driver of ALL, whereas RAG1 and RAG2 have been identified as downstream, activating targets of NOTCH1 in T-ALL (20, 21). This evidence concerns the gene IKZF1 and acute lymphoblastic leukemia.