Strikingly, all SLE sera and commercial antibodies recognizing the set of Ro52 bands in IFN-high SLE neutrophils (Figure 1, C–F) were specific for Ro52α and Ro52γ (Figure 3, D–I), demonstrating that the main epitope targeted by antibodies against the Ro52 neutrophil variants is located within a sequence encoded by exon 4 (hereafter Ro52Ex4), which is missing in Ro52β. Here, TRIM21 is linked to systemic lupus erythematosus.