In humans, CTLA4 and PD-1 polymorphisms were associated with various ADs, including Grave’s disease, autoimmune hypothyroidism, systemic lupus erythematosus, mild glomerulonephritis, cardiomyopathy, ankylosing spondylitis, rheumatoid arthritis (RA), type 1 diabetes, and CD [41,42,43,44,45,46]. Here, CTLA4 is linked to rheumatoid arthritis.