Besides activating alterations, including mutations, deletions and gene rearrangements that affect IL7R, SH2B3, JAK1, JAK2, JAK3, TYK2, IL2RB, EPOR or TYK2, also CRLF2-overexpressing ALL show aberrancies on the JAK/STAT pathway [109]. The gene discussed is TYK2; the disease is acute lymphoblastic leukemia.