BTG3 and systemic lupus erythematosus: To further delineate the phenotypic diversity among late-onset SLE patients, we performed two-step cluster analysis on 12 autoantibodies: ANA, anti-dsDNA, anti-nucleosome, anti-histone, anti-Sm, anti-SSA/Ro52, anti-SSA/Ro60, anti-SSB/La, anti-snRNP, anti-RPP, anti-β2 GPI, ACA.