ABL1 and acute lymphoblastic leukemia: At diagnosis around 67% of pediatric Ph+ ALL patients also have Ink4-Arf deletion (Arf−/−) (hereafter called BCR-ABL ALL or BCR-ABL+ ALL) and approximately 80% have IKAROS (IKZF1) alterations, which are considered hallmarks for high-risk B-ALL19,20.