Thus, Ftx−/− females progressively develop a splenomegaly during aging, which is accompanied by multiple markers of SLE, including high levels of spontaneous lymphocyte activation, increased percentages of ABC-like and GC B cells, overproduction of immunoglobulins (IgM and IgG), including IgG autoantibodies to NA and RNP-Sm, and a predominance of atypical Ly6Clo monocytes in the circulation. The gene discussed is XK; the disease is Splenomegaly.