In patients with AITL, the lymphoma‐associated TET2 mutations are frequently seen in haematopoietic progenitor cells and several lineages of non‐neoplastic cells including B and CD8+ T‐cells, which are polyclonal as reported to date 7, 13, 14, 16, 21. The gene discussed is TET2; the disease is angioimmunoblastic T-cell lymphoma.