In T-ALL, different subtypes are characterized by sequence mutations or copy number alterations in, e.g., NOTCH1 or FBXW7 as well as subtypes showing deregulated expression of genes encoding specific transcription factors (e.g., TAL1, LMO1, LMO2, TLX3 and MYC), generally due to chromosomal deletions [200]. The gene discussed is NOTCH1; the disease is acute lymphoblastic leukemia.