In humans, mutations in FcγRIIB have been associated with systemic lupus erythematosus (SLE) [3, 4], and memory B cells and PCs in individuals with SLE express lower levels of FcγRIIB as compared to memory B cells and PCs in healthy individuals [5], a factor that is suggested to contribute to disease [6]. Here, FCGR2B is linked to systemic lupus erythematosus.