AFF1 and acute lymphoblastic leukemia: Among the 8120 CpG sites identified within the twin samples, 5139 were also differentially methylated with similar effects (i.e., t-test mean differences of at least 30%) and the same directions among the three diagnosis–remission-matched samples (couples A1d–A1r, A2d–A2r, and A3d–A3r) which were derived from three independent (and unrelated) B-ALL infants carrying the KMT2A/AFF1 chromosomal rearrangement (Supplementary Table S2).