We did detect low-frequency TP53 mutations at diagnosis, including the TP53R248Q (n = 2) which has been shown to be enriched at relapse in ALL.41 The 2 patients with diagnostic TP53R248Q relapsed, P22 had a testis relapse from which we had no material, but in the other patient (P3) the TP53R248Q was lost at relapse and instead a clone with NRASG13D expanded (Figure 3A). Here, TP53 is linked to acute lymphoblastic leukemia.