ABL1 and precursor B-cell acute lymphoblastic leukemia: Five of 26 (19.2%) adult and two of 75 (2.7%) pediatric B-ALL cases without canonical B-ALL alterations (5/38 (13.2%) adult and 2/122 (1.6%) pediatric BCR-ABL1-negative B-ALL cases) were positive for either ABL-class or JAK-STAT pathway fusions (AJS-positive group) (Table 3).