RNPC3 and systemic lupus erythematosus: Familial aggregation of anti-Sm/RNP, anti-P, and anti-Ro60 in SLE patient sibling pairs was observed.SLE patients of Simplex-pedigree had a greater positivity of anti-dsDNA (P = 0.0003) and anti-chromatin (P = 0.005) compared to patients with a multiplex SLE pedigree.