SNRPD1 and systemic lupus erythematosus: We found that the concentration of anti-SmD1 autoantibodies was significantly higher in the SLE group (1630.6 ± 6686.9 U/ml) than in the RDC group (15.3 ± 43.3 U/ml; P = 0.000) or the HC group (25.1 ± 105.7 U/ml; P = 0.000).