NOTCH1 and acute lymphoblastic leukemia: NOCTH1 role in leukemogenesis was initially identified in the rare chromosomal translocation t(7;9)(q34;q34.3) that fuses the intracellular form of NOTCH1 to the TCR beta and leads to the expression of TAN1, a truncated and constitutively activated form of NOTCH1; subsequently, activating or loss of function mutations has been identified in more than 50 % of T-ALL cases, representing the most common alteration in T-ALL.