Rheumatoid arthritis is one of several "autoimmune" diseases, so-called because a person's immune system attacks his or her own body tissues.
Scientists still do not know exactly what causes this to happen.
Genetic Factors : Scientists have found that certain genes that play a role in the immune system are associated with a tendency to develop rheumatoid arthritis.
At the same time, some people with rheumatoid arthritis do not have these particular genes, and other people have these genes but never develop the disease.
This suggests that a person's genetic makeup is an important part of the story but not the whole answer.
It is clear, however, that more than one gene is involved in determining whether a person develops rheumatoid arthritis and, if so, how severe the disease will become.
Other Factors : Some scientists also think that a variety of hormonal factors may be involved.
These hormones, or possibly deficiencies or changes in certain hormones, may promote the development of rheumatoid arthritis in a genetically susceptible person who has been exposed to a triggering agent from the environment.
Rheumatoid arthritis develops as a result of an interaction of many factors.
Environmental Factors : Many scientists think that something must occur to trigger the disease process in people whose genetic makeup makes them susceptible to rheumatoid arthritis.
An infectious agent such as a virus or bacterium appears likely, but the exact agent is not yet known.
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