However, in contrast with the finding in SSc or PM/DM, frequent coexistence of disease-specific autoantibodies has been reported in SLE [32]; many patients have more than one of anti-Sm, anti-dsDNA, and anti-ribosomal P. The present study suggests that anti-RPA-positive patients may form a unique group of SLE without other autoantibodies commonly found in SLE. This evidence concerns the gene RPA1 and systemic sclerosis.