Separate analyses of APRIL levels in SLE patients with NPSLE and patients without CNS disease revealed that NPSLE patients had 1.5 times higher APRIL levels in CSF compared with SLE patients without overt CNS disease (13,677 ± 9,725 versus 8,672 ± 9,725 pg/mL; Figure 2a). The gene discussed is TNFSF13; the disease is systemic lupus erythematosus.