Created on: 01/04/08 - Email to friend - Print Page

Frequently Asked Questions About Rheumatoid Arthritis

About Rheumatoid Arthritis

What is rheumatoid arthritis?

Rheumatoid arthritis (rue-ma-TOYD arth-write-tis) is a chronic inflammatory disease of the joints that affects an estimated 1.3 million Americans. The disease occurs when the body’s immune system – which normally protects from us from infection – mistakenly attacks the synovium, the thin membrane that lines the joints. The result can be joint damage, ongoing pain, inflammation, loss of function and disability.

The joints most commonly affected by RA are those of the hands, feet, wrists, knees, elbows, knees and ankles. Joint involvement is usually symmetrical, meaning if one joint is affected, the same joint on the opposite side of the body is affected as well. The disease can also affect many organs, including the skin, heart, blood vessels and lungs.

Although RA is a chronic disease, its symptoms can come and go. Periods of mild disease activity can be punctuated by flares, or periods or more intense disease activity and symptoms. In some cases, with appropriate treatment, the disease may become inactive and symptoms may go away completely.

What is an autoimmune disease?

An autoimmune disease is one that results when the body’s immune system – its natural system of defense against intruders such as viruses, bacteria and fungi – mistakenly turns its attack on the body’s own cells and tissues.

There are many different autoimmune diseases, including lupus, multiple sclerosis and type 1 diabetes, affecting many different tissues of the body.

In rheumatoid arthritis, the primary site of the attack is the synovium, the thin layer of tissue lining the joints. But the immune system may also attack other tissues, such as the lungs and the lining of the heart.

What causes rheumatoid arthritis?

Despite extensive research, the cause of rheumatoid arthritis remains unknown. However, most doctors agree that a combination of genetic and environmental factors is responsible.

Over the past 20 years, and especially in the past year or two, progress has been made toward identifying genes linked to an increased risk of rheumatoid arthritis. One such factor found on the surface of white blood cells, or lymphocytes, is known as major histocompatability antigen, or human leukocyte antigen (HLA). The HLA genetic site, or locus, controls immune responses.

Researchers have shown that people with a specific genetic marker called the HLA shared epitope have a fivefold greater probability of developing RA than do people without the marker. Other more recently identified genes with a connection to RA include: STAT4, a gene that plays important roles in the regulation and activation of the immune system; TRAF1 and C5, two genes relevant to chronic inflammation; and PTPN22, a gene associated with both the development and progression of RA.

Yet not all people with these genes develop RA and not all people with RA have these genes, so researchers are investigating other factors that may play a role. Suspects include infectious agents such as bacteria or viruses, which may trigger development of the disease in someone who has the genetic propensity for it; female hormones (70 percent of people with RA are women) and the body’s response to stressful events such as physical or emotional trauma.