Panel A: gene-gene interaction network of 7 SNPs associated with susceptibility to active arthritis. Significant GxG interactions (FDR<0.05) are connected by line, and the strength of interaction is labeled with pOR. A larger pOR indicates a stronger interaction (thicker line) while a smaller pOR value indicates a relatively milder interaction (thinner lines). Panel B: ROC curve for risk scores derived from 82 significant two-locus interactions pooled from 34 SNPs. The risk score is significantly higher in patients with a poor response to MTX (active arthritis; inset).