Recurrent gene mutations have been identified in nodal T-cell lymphomas, including those in ten-eleven translocation 2 (TET2) in 20–83%, isocitrate dehydrogenase 2 (IDH2) in 0–45%, and ras homolog family member A (RHOA) in 17–71%, depending on the subtypes and DNA methyltransferase 3A (DNMT3A) in approximately 30%, independent of the subtypes.8, 9, 10, 11, 12, 13 Mutations in TET2 encoding a methylcytosine dioxygenase and those in DNMT3A encoding a DNA methyltransferase presumably result in epigenetic abnormalities in nodal T-cell lymphomas. The gene discussed is DNMT3A; the disease is T-cell non-Hodgkin lymphoma.