Belimumab—a recombinant monoclonal IgG1λ antibody that antagonizes circulating BAFF—was approved as add-on therapy in adults with active, auto-antibody positive SLE with a high degree of disease activity despite standard therapy, after the results of two pivotal phase 3 clinical trials and a subsequent trial for LN [29–31]. The gene discussed is TNFSF13B; the disease is systemic lupus erythematosus.