IKZF1 and acute lymphoblastic leukemia: In contrast, the BCR-ABL1 t(9;22) (q34;q11.2) ALL subtype with IKZF1 del and mut, CDKN2A/B del, has a prevalence of about 5% in children, while it is higher in adults (40–50%), and this is associated with a historically poor prognosis, which is improved with TKI [142,143,144].