SLE patients carrying the BAFF-var allele exhibited increased disease activity at study entry, as determined by the physician’s global assessment (PGA: p = 0.002; OR, 4.8; 95% CI, 1.54–14.93) and the SLE Disease Activity Index (p = 0.012; OR, 3.5; 95% CI, 1.12–11.18). Here, TNFSF13B is linked to systemic lupus erythematosus.