FCGR2B and systemic lupus erythematosus: The lupus-prone murine model FcγRIIB-/-yaa on a C57BL6 (B6)-background was generated and first described in 2002 by Bolland et al. In these mice, lack of inhibitory FcγRIIB on immune cells combined with the Y-chromosome linked autoimmune accelerator (yaa) mutation causes an especially severe variant of glomerulonephritis in male mice [7].