There is also emerging data on the multi-step tumourigenesis of AITL, where TET2 and DNMT3A mutations have been found in multiple morphologically normal cell lineages as well as in the tumour tissue of AITL patients, suggesting that AITL may originate from TET2 and DNMT3A mutated premalignant clones [25,26,27]. The gene discussed is TET2; the disease is angioimmunoblastic T-cell lymphoma.