In PTCL, particularly AITL, mutations in RHOA, DNMT3A, and IDH2 genes are also common, and TET2 mutations often co-exist with these mutations [97,98,99,100], consistent with a notion that TET2 mutations may cause preleukemic conditions and require additional mutations to drive full-blown diseases. The gene discussed is TET2; the disease is angioimmunoblastic T-cell lymphoma.