Zeroing In on 3 Autoimmune Diseases

Genetic Link May Help Explain Diseases From Psoriasis to Lupus

By Jennifer Warner
WebMD Health News

Reviewed by Brunilda Nazario, MD

Nov. 10, 2003 -- New discoveries about a set of genes may help unlock the mystery behind who can get an entire family of diseases from rheumatoid arthritis to lupus.

Researchers have long suspected that people with a group of diseases of the immune system known as autoimmune diseases may share a set of genes that put them at risk for these disorders.

But new research takes them a step closer to identifying which genes might be responsible for at least three of these diseases: rheumatoid arthritis, lupus, and psoriasis.

Although the causes of most autoimmune diseases are unknown, researchers suspect that a combination of genetic susceptibility and environmental factors may contribute to a person's risk of developing these diseases.

Genetic Links for Psoriasis, Rheumatoid Arthritis, and Lupus

In the first study, researchers identified a gene that increases a person's susceptibility to psoriasis, an inflammatory skin disorder that affects about 2% of the population. The gene is one that turns switches to the immune system on and off, and a defective version of this gene has been found in a significant number of people with psoriasis.

In the second, researchers found a genetic defect that may increase the risk of rheumatoid arthritis. Rheumatoid arthritis is a progressive disease that causes the lining of the joints to become inflamed, swollen, and painful.

Researchers say the genetic influence on rheumatoid arthritis risk seems especially strong. Siblings of people with the disease have a 2 to 17 times higher risk of developing rheumatoid arthritis themselves compared with the general population.

A third study showed that a rare genetic variant may play a role in the susceptibility for the development of lupus, a complex disease of the immune system that affects virtually all tissues of the body. It commonly affects women and for most is a mild disorder, but it can cause life-threatening damage to many organs in others.

Researchers say that these findings build on previous research suggesting that these diseases may share a common genetic bond, and these studies provide new clues about how these genes interact to trigger development of autoimmune diseases.

If further studies confirm these results, researchers may eventually be able to develop genetic screening tests for certain autoimmune diseases or develop more effective treatments.

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