SNRPD1 and systemic lupus erythematosus: In this study, we applied a SmD1 (Peptide aa 83–119) polypeptide-based enzyme-linked immunosorbent assay (ELISA) to detect anti-SmD1 antibodies in patients with SLE, patients with other autoimmune diseases, and healthy volunteers to explore the positivity and specificity of anti-SmD1 antibodies in naive SLE patients (those not previously treated with steroids or immunesuppressants at the inception of the study) and non-naive SLE patients as well as the associations between anti-SmD1 antibodies and clinical features of SLE.