is the second most common type of arthritis and the most severe. It affects 5 to 8 million Americans. may begin at any age, but is most common to strike people in their 30’s and 40’s. When it affects children, it is termed Juvenile . It affects women three times more often then men. The cause of is unknown, but it is clear that the immune system is linked. The immune system normally protects against foreign invaders and disease. Instead, in , it attacks the joints, especially the synovium (joint lining), which results inflammation. I ....