Causes
RA is an autoimmune disease. This means that the body's immune system fails to recognize its own tissue and views it as a foreign invader. In the case of RA, the immune system attacks mostly the joints, but it can affect other organ tissues as well.
It's hard to determine who will develop RA. It is believed that RA may be caused by a combination of factors, including genetic risk and environmental factors. If someone has a close relative that has RA, they have a 2 to 3 times higher risk of having RA.