TRIM21 and arthritic joint disease: Indeed, these three chronic diseases have in common demographic distribution (the most affected individuals are women), some signs and symptoms (arthritis, lung and vascular disease), serological elements (ANA and anti-Ro52/TRIM21 antibodies), immunological components (type I interferon signature and complex abnormalities in CD4C T lymphocyte function, in particular Th17 and Treg cell subsets), and genetic similarities (e.g., MHC class II alleles, IRF5, STAT4, PTPN22 loci) [38–44].