IL1B and systemic-onset juvenile idiopathic arthritis: In this study we have utilised a large cohort of JIA cases and identified associations between UK JIA and polymorphisms in three genes: MVK, TNFRSF1A, and IL1A. These findings follow on from work performed by our group, showing associations between psoriatic JIA and other HPF syndrome genes, and work previously showing associations between SoJIA and the IL1 ligand and IL1 receptor gene clusters [7,18].