Using this model, we previously showed that a long-term Dnmt3a-defficiency resulted in the development of a chronic lymphocytic leukemia (CLL) in 68% of mice, CD8-positive mature T cell lymphomas (PTCL) in 14% mice and mixed CLL/PTCL in 18% cases within one year of age9, 11. The gene discussed is CD8A; the disease is T-cell non-Hodgkin lymphoma.