PTPN22 and juvenile idiopathic arthritis: The use of the Immunochip has helped to refine peaks of association identified in previous GWAS and increase sensitivity in discovering new risk loci; in a well-powered study of ~2,000 patients with either oligoarticular or rheumatoid factor (RF)-negative polyarticular JIA, three known JIA risk loci (the HLA region, PTPN22, and PTPN2) and 14 novel loci reaching genome-wide significance (p < 1 × 10−6) were uncovered for the first time (14).