This study identified a genetic variant that makes a person susceptible to rheumatoid arthritis. It drew a link between the disease and a variant of gene PTPN22. This variant is present in about 28 percent of white people with rheumatoid arthritis, but only about 17 percent of the general white population. This variant recently was implicated in type 1 diabetes, suggesting there are common genetic variants that can raise an individual's risk for autoimmune diseases.

In the first phase of this study, researchers scanned the genome of 475 people with rheumatoid arthritis and compared them with 475 healthy controls to identify variants more common in people with the disease.

Everybody in the study was white and had developed the disease between the ages of 18 and 68. Special attention was given to 87 genetic variants that were considered to be potentially associated with the disease.

To confirm that the variants identified in the first phase were indeed associated with rheumatoid arthritis, the study was replicated in a second group of 463 people with rheumatoid arthritis, each also having at least one sibling with the disease, as well as a control group of 926 people.

More: To read an abstract of this paper on PubMed, a medical database, click here.