In patients with AITL, the lymphoma associated TET2 and DNMT3A mutations most likely occur at an early stage of haematopoiesis, as they are also observed in several lineages of non‐neoplastic cells including non‐neoplastic B and CD8+ T cells 7, 13, 14, 16, 21, 22. The gene discussed is DNMT3A; the disease is lymphoma.