RNPC3 and mixed connective tissue disease: As controls, sera from 70 patients with other connective tissue diseases were included: systemic lupus erythematosus [SLE] being positive for antibodies to double stranded DNA, SSA/Ro or Sm: n=21; mixed connective tissue disease [MCTD] being anti-RNP positive: n=25, primary Sjoegren syndrome [pSS] positive for anti-SSA/Ro: n=24.