Although T-ALL shares abnormalities with B-ALL, such as the rearrangement of t(v;11q23) (MLL) or the deletion of CDKN2A/B [20], there are specific gene deregulations in this subtype, such as (1p32) (TAL1), (11p13) (LMO2), (10q24) (TLX1/HOX11), (5q35) (TLX3/HOX11L2) [21], fusion (9q34) (NUP214-ABL1) [22], mutations of (9q34.3) (NOTCH1) [23], and loss of (4q31.3) (FBXW7) and (10q23) (PTEN) [24]. The gene discussed is NOTCH1; the disease is acute lymphoblastic leukemia.