SNRPD1 and systemic lupus erythematosus: Positivity for anti-Sm only was 8.0% in the naive SLE group, which was higher than 1.2% in non-naive SLE (χ2 = 6.36, P = 0.012), which indicates the positivity of anti-Sm was affected more readily by treatment than was the presence of anti-SmD1.