We describe here a protein microarray chip for the parallel detection of autoantibodies in the serum of patients withautoimmune diseases, including systemic lupus erythmatosus (SLE), mixed connective tissue disease (MCTD), Sjögren's syndrome (SS), Sjögren's syndrome A (SSA), Sjögren's syndrome B(SSB), Smith (Sm), Ribonucleoprotein (RNP), Scleroderma (Scl), systemic sclerosis (SSc), dermotomyositis (DM), double-stranded DNA(dsDNA), Phosphate-Buffered Saline Tween-20(PBST), and polymyositis (PM). The gene discussed is RNPC3; the disease is systemic sclerosis.