No correlation was observed between RAG1 or RAG2 expression and ESC copy numbers (Extended Data Fig. 4c) and even in BCP-ALL samples in which RAG1 expression was very similar, increased ESC copy numbers were observed in patients who later relapsed but not in those who did not (Fig. 2c; P = 0.0156). The gene discussed is RAG1; the disease is acute lymphoblastic leukemia.