In this study we show that loss of Dnmt3a in HSPCs in EμSRα-tTA;Teto-Cre;Dnmt3afl/fl; Rosa26LOXPEGFP/EGFP mice not only results in the development of CLL as we reported previously [16,17] but also in the development of peripheral T cell lymphomas in ~40% of Dnmt3aΔ/Δ mice either alone or in combination with CLL. The gene discussed is DNMT3A; the disease is peripheral T-cell lymphoma, not otherwise specified.