Notably, Late-Pro patients showed good prognosis despite frequent single-copy losses or mutations in IKZF1 (n = 14/22, 64%), suggesting single-copy alterations in IKZF1 are not responsible for the high-risk nature of BCR-ABL1 lymphoblastic leukemia (Supplementary Figs. 20 and 21). Here, ABL1 is linked to acute lymphoblastic leukemia.