Is Rheumatoid Arthritis A Genetic Disease?

Rheumatoid arthritis is affected by genes, but this disease is not controlled by a single gene. As a result, RA generally does not run in families. Instead, scientists believe that RA develops as a result of a complex interaction of genetic and environmental factors. Each person is born with a unique genetic code and has unique environmental exposures.Therefore, even if one of your family members has this disease, your own chances of developing RA are still quite low.

Examining studies of RA development in twins may help to illustrate this point. In some studies of twins, concordance was found—that is, both twins developed RA. If the twins were identical and one twin developed RA, then the chance that the other twin would develop RA was 30%. If the twins were fraternal (not identical) and one of them developed RA, then the chance that the other twin would develop RA was only 5%. From these studies, we can see that while genes have some influence on the chance of developing RA, the risk is still small.

Human leukocyte antigens (HLAs) are proteins on the surface of white blood cells that are associated with the body's immune system. These markers serve as a sort of genetic fingerprint, helping the body recognize infections or tissue transplants that are considered “foreign.” Some HLA markers, such as HLA-DR4, are associated with more severe RA or with complications of RA such as vasculitis (an inflammation of the blood vessels).

Antigen

A foreign protein or carbohydrate complex that causes an immune response.

Vasculitis

Inflammation of blood vessels.

Because many people with RA don't have these markers in their blood, and because many people without RA do have these markers in their blood, HLA-based tests do not provide conclusive proof that someone has RA. Therefore doctors don't typically order this type of test; rather, the tests are generally used for research purposes. HLA-DR4 is one of the best-known genetic associations with RA, but other, less common associations have been identified as well.

Many people know that their parents had arthritis, but a reliable diagnosis of the parent's condition is not available. Your chances of“inheriting” RA from your parents are small, but if you have questions, consult your doctor.

I have a fraternal twin brother who had the same RA and was on the identical medication. He didn't follow the doctor's advice and died of a massive heart attack in 1999. (This was a man on a fool's errand.)