Cause
The cause of
rheumatoid arthritis (RA) is not fully understood.
Genes play a role in rheumatoid arthritis, but experts
do not know exactly what that role is. For most people with RA, the disease
does not run in their families and they do not pass it along to their children.
One or more genes may make it more likely that the body's
immune system will attack the tissues of the
joints. This immune response may also be triggered by
bacteria, a virus, or some other foreign substance.
The abnormal immune response causes ongoing
inflammation of the tissues lining the joint, a
breakdown of
cartilage, and loosening of the ligaments and tendons
supporting the joint. Ongoing inflammation also causes the membrane that lines
the joint (synovium) to grow into a thick, abnormal tissue called pannus. These
processes result in destruction of the cartilage, the underlying bone
surrounding the joint,
ligaments, and
tendons and can eventually lead to deformed
joints.