RA: Rheumatoid arthritis (RA) is an autoimmune disease. It causes joint problems, such as:

Symptoms: pain,swelling,stiffness,loss of function

Who Gets Rheumatoid Arthritis?: Anyone can get RA. It affects about 1% of Americans. The disease is two to three times more common in women than in men, but men tend to have more severe symptoms. It usually starts in middle age. But young children and the elderly also can get it.

What Causes It?: Doctors don't know the exact cause. Something seems to trigger the immune system to attack the joints and sometimes other organs. Some experts think that a virus or bacteria may change the immune system, causing it to attack the joints. Other theories suggest that in some people, smoking may lead to rheumatoid arthritis