TRIM21 and systemic lupus erythematosus: Thus, antibodies to Ro52Nt represent 4.7% (9 of 191) of anti-Ro52 antibodies in the SLE cohort, and this is consistent with a previous study showing that 4% of anti-Ro52–positive SLE sera recognize the N-terminal sequence in Ro52 (amino acid residues 1–127) (28).