MLLT1 and acute myeloid leukemia: To confirm our results showing differences in MLLGA and MLLGB in independent datasets (Supplementary Dataset 3), we collected publicly available mRNA expression data in a cohort of 42 young patients (aged <18 years) with KMT2Ar-AML from Pigazzi et al.30 We considered cases with rearrangements involving MLLT4 and MLLT10 cytogenetically to be similar to our MLLGA and patients with rearrangements involving ELL, MLLT1 and SEPTIN6 similar to our MLLGB.