what causes ra
About RA. Rheumatoid arthritis (RA) is a disease that causes pain, swelling, and stiffness in the joints. In some people, it can also cause the joints to become damaged and deformed.bout RA. Rheumatoid arthritis (RA) is a disease that causes pain, swelling, and stiffness in the joints. In some people, it can also cause the joints to become damaged and deformed.