New insights into the genetic basis of rheumatoid arthritis are reported in two papers published online this week in Nature Genetics.

Rheumatoid arthritis (RA) is an acquired, chronic autoimmune disease, characterized by inflammation of the lining of multiple joints. RA is the most common inflammatory form of arthritis and is influenced by both genetic and environmental factors.

Karin Lundberg and colleagues explore the susceptibility to RA and the interaction of established genetic, environmental and autoimmune factors. These factors include several previously studied genes, environmental factors such as smoking, and a particular immune system antibody. The scientists find that the interaction between the different factors depends on a specific protein, which may mediate the autoimmune response underlying this gene-environment interaction.

In a second paper, Soumya Raychaudhuri and colleagues report three genetic variants found to be associated with RA. They began with a unique approach of analyzing genome-wide association study datasets, using a computational method called GRAIL that predicts functional relationships between genes, and then replicated their findings in an independent set of nearly 8000 RA cases.