Autoimmune diseases are caused by your immune system targeting and attacking cells in your body. This can result in a number of different problems: joint pain (rheumatoid arthritis), scaly, thick skin (psoriasis), hypothyroidism (Hashimoto’s), and more.
CTLA4 keeps the immune response under control and not attacking your own cells.
Variants in CTLA4 increase the risk of a number of autoimmune diseases.