Noncoding lesions unite initial diagnostic and late relapse leukemias. (A) Schematic representation of LMO2 intron 1 duplications identified in 3 cases. (B) Order of acquisition of mutations in initial diagnostic and relapse cases, demonstrating the initiating noncoding lesion that unites the 2 leukemias. (C) Agarose gel of polymerase chain reaction products confirming presence of the noncoding LMO2 duplication in the neonatal blood spot sample from patient P049. Polymerase chain reaction product was confirmed on Sanger sequencing. Lane M, 100-bp molecular weight ladder; lane 1, P049 presentation sample DNA; lane 2, P049 neonatal blood spot DNA; lane 3, no template (water) control. dup, duplication; HomDel, homozygous deletion; L, ladder; Leuk, leukemia; NBS, neonatal blood spot; NTC, nontemplate control.