Elevated circulating BAFF levels are frequently observed in patients with autoimmune disorders such as systemic lupus erythematosus (SLE), rheumatoid arthritis, Sjögren's syndrome and systemic sclerosis, suggesting that BAFF is a pathogenic factor for autoimmune diseases.1, 11, 12, 13. Here, TNFSF13B is linked to systemic lupus erythematosus.