TRIM21 and mixed connective tissue disease: Although their coexistence or isolated positivity may reflect distinct immunopathological mechanisms, research has predominantly focused on anti-Ro52 due to its association with interstitial lung disease (ILD) in connective tissue diseases (CTDs), particularly in antisynthetase syndrome (ASS) (7), systemic sclerosis (SSc) (8, 9), Sjögren’s disease (SjD) (10, 11), and mixed connective tissue disease (MCTD) (12).