FCGR2A and rheumatoid arthritis: In rheumatoid arthritis (RA),9 systemic vasculitis,10 neuromyelitis optic spectrum disorder (NMOSD),11 and systemic lupus erythematosus(SLE),12 both clinical parameters (such as disease severity, age at onset, age at RTX start, and gender) and biomarkers (including the titer of antibodies, the frequency of memory B cells, single‐nucleotide polymorphism(SNP) in BAFF, FCGR3A, FCGR2A, and IL‐12/21) have been shown to be related to treatment response.