Rheumatoid arthritis is a common autoimmune disease. An individual’s own immune system attacks the lining of the joints, causing stiffness and muscle aches. Like other autoimmune diseases, development of rheumatoid arthritis is likely caused by a complex combination of genetic and environmental factors. Research into the genetics of the disease has identified many of the genetic factors. Studies continue to implicate additional variants that may influence risk.
Genetic Associations
A pair of such studies published in Nature Genetics found several genetic variants associated with rheumatoid arthritis.
In Japan, a team led by Yuta Kochi and Kazuhiko Yamamoto from the RIKEN Center for Genomic Medicine identified a variant, associated with rheumatoid arthritis risk. The study included over 2,000 Japanese individuals with the disease and 3,400 individuals free of the disease.
The second study, headed by Eli Stahl and Robert Plenge at Brigham and Women’s Hospital in Boston, confirmed the same association. This second study was done in over 10,000 people of European ancestry with rheumatoid arthritis.
Immune System
One of the variants is in an area of the genome associated with a risk for Crohn’s disease. That region contains a gene called CCR6 that is known to be involved in the immune system.
In follow-up experiments, the RIKEN team demonstrated that the different versions of the variant affect the behavior of CCR6. This provides a potential biological explanation for the variant’s contribution to rheumatoid arthritis risk.
Stahl and his colleagues also found several other genomic regions associated with rheumatoid arthritis in people with European ancestry, some of which had not yet been linked to autoimmune disease.