TRIM21 and systemic lupus erythematosus: Disease activity was assessed using the systemic lupus erythematosus disease activity index-2000 (SLEDAI-2K) score, with organ involvement categorized based on predefined criteria detailed elsewhere.[6] Anti-α-fodrin IgA and IgG antibodies (cut-off ≥10 U/mL), as well as anti-Ro and an-ti-Ro52 antibodies (≥25 U/mL) (Orgentec; Mainz, Germany), were measured by Enzyme linked immunosorbent assay (ELISA).