Finally, the relapse-specific mutations in phosphoribosyl pyrophosphate synthetase 1 gene (PRPS1), a rate-limiting purine biosynthesis enzyme that confers significant drug resistance to combination chemotherapy in acute lymphoblastic leukemia (Wang et al., 2018), suggest that these genes shared could indicate a core of early genes, given that they are also found in NAG, a non-cancerous lesion. Here, PRPS1 is linked to acute lymphoblastic leukemia.