Since fecal IgA levels were higher in lupus-prone SNF1 mice compared to B6 mice and in SNF1 females compared to male counterparts, we determined if the fecal IgA antibodies from SNF1 mice recognize nuclear antigens such as dsDNA and nucleohistones, and this feature correlates with systemic autoimmunity and disease incidence. The gene discussed is CD79A; the disease is systemic lupus erythematosus.