So far, five genes have been found that are linked to the risk of developing rheumatoid arthritis. Scientists hope these genes can lead to effective treatments for rheumatoid arthritis patients.

Why do some people get rheumatoid arthritis, an autoimmune disease that affects the joints, and others do not? Why do some patients respond to certain treatments, while other rheumatoid arthritis patients get no relief from the same treatments?

Scientists hope that the answers to these questions can be found in genetics.

Rheumatoid Arthritis: The Genetic Component

To date, at least five genes have been identified that are specific to the risk for developing rheumatoid arthritis. Genetic factors also play a role in determining how severe rheumatoid arthritis, often called RA, will get.

“Essentially all persons with RA are born with genetic susceptibility factors which, once identified, will allow for better profiling with regard to [outcome] and appropriate therapeutic combinations for that individual patient,” says Joseph Huston, MD, a rheumatologist at Vanderbilt University Medical Center in Nashville, Tenn.

“RA, like nearly all other autoimmune diseases, requires genetic susceptibility and an environmental trigger,” says Dr. Huston. “If the triggering agents can ever be identified, it should then be possible to construct a strategy to keep the susceptible individuals protected” from the triggering agent, for example, by having a vaccine against a virus.

Huston adds: “The susceptible individual would be recognized by their genetic profile, as many susceptibility factors have already been identified and more will surely follow.”

Rheumatoid Arthritis Research: Possible Trigger

Perhaps smoking is one of those triggers.

New research shows that people with a particular gene that puts them at risk of developing rheumatoid arthritis double their chances of getting rheumatoid arthritis if they smoke. The researchers found more protein markers in these people, markers that are usually found in those with rheumatoid arthritis. In people who didn’t smoke but still had the particular gene, their risk was half that of those who did smoke.

Rheumatoid Arthritis Research: Gene Therapy

Also in new, but early, research, researchers at Harvard Medical School found that gene therapy helped, at least temporarily, to relieve pain and swelling in two patients. These two patients received interleukin-1 receptor antagonist, which is used in treating rheumatoid arthritis. The researchers measured pain, the circumference of a joint in the hand, and looked at the lining of the joint, called the synovium, to check results.

Neither patient had any problems with the treatment; one patient had much less pain during the study’s duration of four weeks. Also, the joints receiving the treatment had no flares. And the synovium showed that it had started reproducing its own interleukin-1 receptor antagonist, also known as IL-1Ra.

Rheumatoid Arthritis Research: Factors and Treatment

Genetic factors can also help determine the appropriate drug treatment for patients with rheumatoid arthritis, since how a person’s body breaks down RA drugs is genetically determined to some extent.

“An individual’s genetic makeup does influence how they metabolize and excrete various medications,” says Huston.

John H. Klippel, MD, president and CEO of the Arthritis Foundation in Atlanta, agrees that genetics will some day be used in prescribing RA treatments. “Responses to drug therapy are influenced by genetics,” says Dr. Klippel. “Serious side effects of drugs are also genetically determined.”

Indeed, one of the primary goals of current genetic research involving rheumatoid arthritis is developing an individualized drug therapy that would be safer and more effective. Huston says if this goal is reached, more effective treatments could be given at the start of treatment, “rather then having to rely on a trial-and-error approach that rotates through various options.”

Knowing the genetic makeup of an RA patient could help prevent exposure to potentially dangerous drugs. And a tailored drug regimen could save money, as the trial-and-error approach would be eliminated.

Says Klippel: “Genetics is definitely an exciting area for RA doctors and their patients.”