B-cell activating factor (BAFF) and APRIL pathways, both members of the tumor necrosis factor (TNF) superfamily, play a critical role in the activation, survival, and maturation of B-cells, and are involved in many disorders like transplantation/graft versus host diseases (GVHD) and autoimmune diseases (35). The gene discussed is TNFSF13B; the disease is graft versus host disease.