At the other end, there are (i) the E2A-PBX1 PFG generated by the t(1;19) chromosome translocation, which might arise in most cases postnatally in B-cell precursors as most neonatal blood spots were tested negative for E2A-PBX1 sequences [6], and (ii) the T-cell precursor ALL initiating oncogenic mutations and clone-specific molecular markers seem to be generated after birth as suggested by a study in which the positivity was found only in 1/16 of Guthrie cards, despite using PCR approaches with a sensitivity level up to 10-5 [7]. This evidence concerns the gene PBX1 and acute lymphoblastic leukemia.