Thus, by inhibiting natural antibody secretion (IgM and IgA) and favoring adaptive antibody responses, TNFRSF13B diversity establishes varying susceptibility to infection (9, 38), autoimmunity (39, 40), immunodeficiency (15, 21, 41–43), and excessive inflammatory reactions to transplantation and perhaps to pathogens as well. The gene discussed is TNFRSF13B; the disease is Immunodeficiency.