Furthermore, taking into account the sample size limitation of whole-exome sequencing, we also decided to include nine additional genes in our analyses: PAX5, CDKN2A/B, IKZF1/IKAROS, VPREB1, EBF1, TCF3/E2A, NR3C1 and ETV6. In recent studies using genome-wide copy number analyses, expression arrays, and methylation analyses, mutations within each of these genes were identified in relapsed ALL child patients following chemotherapy [10–17]. This evidence concerns the gene IKZF1 and acute lymphoblastic leukemia.