DNMT3A and chronic graft versus host disease: The TBI dose was subsequently reduced to 9 Gy in order to mitigate early mortality and provide the opportunity to study the effect of DNMT3a activity in an established model of chronic GVHD; as previously described, reducing the TBI dose in certain strain combinations can result in a chronic GVHD phenotype by modifying the synergistic effect of TBI and T cell dose on induction of alloreactivity (29, 31, 32).