Our results suggest that deficiency of Bank1 limits lupus endo-phenotypes by reducing the production of type I IFN by B cells, disturbed B lymphoid and myeloid lineage development, the production of IgG antibodies, and the production of pro-inflammatory cytokines such as IL-6, all constantly under enhanced pressure by the excessive expression of Tlr7 found in the Yaa locus. Here, TLR7 is linked to systemic lupus erythematosus.