Detection of the P2RY8-CRLF2 in neonatal blood spots. Amplification plots of the qRT-PCR of genomic P2RY8-CRLF2 using whole genome–amplified genomic Guthrie card DNA of 6 ALL cases: 400 (A), 737 (B), 802 (C), 833 (D), 841 (E), and 887 (F). Standard curves showing a quantitative range of 1 × 10^-5 (blue) and PCR products of Guthrie card DNA from 4 aliquots in triplicates (red). PCR products for P2RY8-CRLF2 with a newly identified genomic breakpoint of case 873. (G) Amplification of the genomic breakpoint. Dilution series of genomic leukemia DNA. (Left) First round. (Right) Second round. The fusion can be detected at the single cell level at 1 × 10^-5 (lane 5). Lane 1, size marker; lane 2, H₂O; lane 3, DNA mix from peripheral blood MNCs of healthy donors; and lanes 4 to 9, 10-log dilutions from 1 × 10^-6 to 1 × 10^-1. Amplification of P2RY8-CRLF2 in native (H) and whole genome–amplified Guthrie card (I) DNA. Lane 1, size marker; lane 2, H₂O; lane 3, control DNA mix; and lanes 4 to 10, Guthrie cards DNA from a newborn who did not develop ALL later. a to i, PCR products from aliquots of the patients' Guthrie card DNA.