AFF1 and acute lymphoblastic leukemia: We analyzed 50 BCP-ALL patient trios, initial diagnosis (ID), complete remission (CR) and relapse (REL), including 26 pediatric and 24 adult patients lacking recurrent cytogenetic rearrangements as assessed by the conventional diagnostic workup (BCR-ABL1, KMT2A-AFF1, ETV6-RUNX1, TCF3-PBX1).