TNFSF13B and systemic lupus erythematosus: Given the recently identified association between serum BAFF levels and autoantibodies against the NR2 subunit of N-methyl-D-aspartate receptor (NMDAR) and motor fatigue in systemic lupus erythematosus (SLE) patients (86), it would be highly interest to test whether anti-NMDAR autoantibodies could contribute to fatigue levels in primary SS patients as well.