While there was no significant difference in RA development between Irg1+/+ and Irg1−/− mice, Irg1−/−/TNF-Tg mice exhibited an earlier onset of arthritis, with visible ankle swelling by 6 weeks when compared to their Irg1+/+/TNF-Tg counterparts (Fig. S5b). The gene discussed is TNF; the disease is arthritic joint disease.