TRIM21 and mixed connective tissue disease: In our analysis of the distribution of the intensity of the positive reactions, we found that antibody levels did not differ substantially for the full Ro52 molecule, but they did for fragment 2 (103 ± 38 grayscale units) and for the 200–239-aa peptide (53 ± 49), which displayed a higher antibody level in the MCTD and SjS cohorts (Fig. 2).