HLA-C and rheumatoid arthritis: Expression of HLA-C in T cells showed strong causal association with autoimmunity, in particular positive causal effects on psoriasis, SLE, PSC, multiple sclerosis, IBD, and ulcerative colitis; and negative causal effects on juvenile idiopathic arthritis, PBC, and rheumatoid arthritis (Fig. 5, Supplementary Figs. 13, 14).