TET2 and mature T-cell and NK-cell non-Hodgkin lymphoma: Particularly, TET2 mutations are highly recurrent events in peripheral T-cell lymphoma (PTCL) such as angioimmunoblastic T cell lymphoma (AITL; 33~63%) and PTCL, not otherwise specified (PTCL-NOS; 20~36%) [95,96,97].