Rheumatoid arthritis is one of a number of autoimmune diseases, meaning it occurs because the body's natural defense system, which is designed to fight off disease and infection, isn't working properly. In the case of RA, the result is inflammation that shows up mainly in the joints, especially in the fingers and wrists, but also in the knees, hips and feet. It can also affect other systems in your body. The mechanism for the malfunction of the immune system isn't clearly understood, but doctors and researchers have made some progress in identifying who might be most at risk of developing RA.
Risk Factors for Rheumatoid Arthritis
By a 2-to-1 margin, more women than men get rheumatoid arthritis, and many of those women have increased symptoms following a pregnancy. Age is also a factor. While you can get RA at any age, it most commonly strikes people between the ages of 30 and 60. Smoking is another risk factor for RA.
Genes And Rheumatoid Arthritis
Lots of research has been done to determine if rheumatoid arthritis is an inherited condition, somewhat like muscular dystrophy. However, it's not quite so direct for the autoimmune diseases, including rheumatoid arthritis. The genetic marker HLA-DR4 (part of the human leukocyte antigen genetic group, a big contributor to our autoimmune system) is found in upwards of 70 percent of Caucasians with RA, and it is found in more than one generation of many families. Still, having the HLA-DR4 marker isn't considered diagnostic, because not everyone with the disease has the marker, and not everyone with the marker gets the disease. And while RA frequently runs in families, researchers believe it's not actually the disease, but the susceptibility for getting it that's inherited and many different genes are likely involved.
Inheriting the Susceptibility for Rheumatoid Arthritis
Basically, inheriting susceptibility to RA means that you need to have both the genetic predisposition for the disease and an environmental "trigger" that starts the process. Estrogen may be one such trigger. Another strong contender is infection. Indeed, the National Institute of Arthritis and Musculoskeletal and Skin Diseases notes in a report published on its website that "...for a subset of people with RA, an initial bacterial infection could prime the immune system for a later inflammation of normal tissue."
