As SLE risk alleles for FCGR2B diminish the functionality of FcγRIIB, patients with SLE with a risk allele for FCGR2B may have a greater impairment of MZ B cells and may have the highest levels of MZ-derived autoantibodies and the largest fluctuation in autoantibody titers. Here, FCGR2B is linked to systemic lupus erythematosus.