Rheumatoid Arthritis Causes
The cause of RA is not yet fully understood, although doctors do know that an abnormal response of the immune system plays a leading role in the inflammation and joint damage that occurs. No one knows for sure why the immune system goes awry, but there is scientific evidence that genes, hormones and environmental factors are involved.
Researchers have shown that people with a specific genetic marker called the HLA shared epitope have a fivefold greater chance of developing rheumatoid arthritis than do people without the marker. The HLA genetic site controls immune responses. Other genes connected 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 rheumatoid arthritis. Yet not all people with these genes develop RA and not all people with the condition have these genes.
Researchers continue to investigate other factors that may play a role. These factors include infectious agents such as bacteria or viruses, which may trigger development of the disease in a person whose genes make them more likely to get it; female hormones (70 percent of people with RA are women); obesity; and the body’s response to stressful events such as physical or emotional trauma. Research also has indicated that environmental factors may play a role in one's risk for rheumatoid arthritis. Some include exposure to cigarette smoke, air pollution, insecticides and occupational exposures to mineral oil and silica.