Genetic Factors Play Small Role in Rheumatoid Arthritis.




British Medical Journal

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Current medical thinking views rheumatoid arthritis as an "autoimmune disease." In autoimmune diseases, for reasons that are not completely understood, the immune system attacks the body's own tissue as though it were a foreign invader. People with rheumatoid arthritis produce an immunity-related substance called "rheumatoid factor" that targets the synovial membrane. The consequences are severe pain and inflammation, joint disfigurement, and loss of joint movement and function.

As if the destruction rheumatoid arthritis inflicts on joints was not bad enough, other parts of the body suffer as well. The disease can cause a host of other potentially serious conditions including eye inflammation, neurological problems, inflamed blood vessels, disorders of the lymph system, and even heart trouble. One distinguishing feature of RA is the appearance of prominent bony lumps called "nodules" over joints.

The symptoms of RA usually develop gradually over several weeks to months. Initial symptoms include fatigue, weakness, low-grade fever, loss of appetite, and joint pain. The hands, feet, and wrists are the most common places where RA joint pain is felt, although the elbows, shoulders, hips, knees, and ankles may also be involved. Joint pain and stiffness often precede any noticeable swelling. Joint stiffness is typically worse in the morning.

A recent study published in the February issue of British Medical Journal investigated the importance of genetics in the prevalence of rheumatoid arthritis (RA). These cohort studies used a twin registry and the Danish discharge and death registries as well. Over 37,000 twins were sent a questionnaire regarding rheumatic diseases. Medical records and a medical examination verified those whom reported RA. Over 84% of the twins responded to the questionnaire. RA was confirmed in 13 pairs of identical twins and 36 pairs of fraternal twins. These results portrayed little significance of genetics. This study concluded that genetic factors play a small role in the incidence of rheumatoid arthritis.1


1. Svendsen AJ. Relative importance of genetic effects in rheumatoid arthritis: historical cohort study of Danish nationwide twin population. BMJ. Feb 2002;324:264.