The fact, that administration of cit-fibrinogen to wild-type C57BL/6 mice and immunization of DR4 Tg mice with native fibrinogen failed to induce arthritis and citrulline-specific reactivity, underscores the critical role of both SE-containing HLA-DR molecules and antigen citrullination in the development of RA (149). The gene discussed is TNFRSF10A; the disease is rheumatoid arthritis.