Association of gene mutation in the RAS pathway with poor therapeutic outcome in childhood ALL is controversial.32, 33, 34, 35 However, gene mutation in the RAS pathway is frequently observed in patients’ samples of t(17;19)‐ALL.17 Thus, we sequenced four RAS pathway genes (KRAS, NRAS, PTPN11, and NF1) in t(17;19)‐ALL and t(1;19)‐ALL cell lines using a next generation sequencer (Table 4, Figure 6A). The gene discussed is PTPN11; the disease is acute lymphoblastic leukemia.