Belimumab is an IgG-1λ monoclonal antibody that specifically targets B-lymphocyte activating factor (BAFF), also called B-lymphocyte stimulator (BlyS), inhibiting the maturation and survival of autoantibody-producing B cells, which play a driving role in SLE pathogenesis. This evidence concerns the gene TNFSF13B and systemic lupus erythematosus.