NOTCH1 and acute lymphoblastic leukemia: However, while a hyperactive NOTCH pathway is observed in virtually all T-ALL cases, a subset of patients does not have pathway-activating mutations in NOTCH1 or FBW7, or the TCR: NOTCH1 translocation; despite extensive analyses, no other mutations in the Notch pathway have been linked to T-ALL in human patients [27,28].