Risk Factors and Causes of RA
The cause for RA is unknown; however, the immune system plays a very important role in disease development. Rheumatoid arthritis occurs as a result of an abnormal immune system response, but the cause for this abnormal response has not been identified.
Approximately 70–80 percent of patients who have RA also have high levels of an antibody called rheumatoid factor, which may indicate an immune system abnormality. An antibody is a protein that is produced in response to antigens (cell markers). Not all people who have high levels of rheumatoid factor have RA, and not all patients who have RA have elevated levels of rheumatoid factor.
Risk factors for rheumatoid arthritis include gender (the disease is 2 to 3 times more common in women) and genetics (heredity). Because RA often is affected by pregnancy—symptoms improve before the infant is born and then worsen after delivery—it may be that hormones in the body influence disease development and progression.
Several genes have been identified that increase the risk for developing rheumatoid arthritis. For example, the genetic marker HLA-DR4 has been identified in as many as 66 percent of patients with disease. This marker, which is present in white blood cells, plays a role in helping the immune system to distinguish between foreign cells (e.g., germs) and the body's own cells.