TRIM21 and lupus nephritis: The recurring association between specific autoantibodies and organ-specific damage illustrates their precision: anti-MDA5 predicts rapidly progressive interstitial lung disease (RP-ILD) in dermatomyositis with 70–90% positive predictive value [12]; anti-RNA polymerase III identifies scleroderma renal crisis risk and paraneoplastic disease [13]; anti-Ro (anti-SSA/TRIM21) signals systemic involvement and elevated lymphoma risk in Sjögren’s disease (SjD) [14]; anti-C1q correlates with lupus nephritis flares [15].