TNFSF13B and systemic lupus erythematosus: Compared to healthy controls (HC), patients suffering from SLE harbour significantly higher serum BAFF levels.2 Serum BAFF has also been reported to be associated with disease activity and autoantibody levels in some studies.2 The efficacy of a BAFF‐targeting therapy, belimumab,5, 6 gives weight to the fact that BAFF plays a critical pathogenic role in SLE.