HLA-DRB1 and polyarticular arthritis: HLA-DRB1*04 is associated with Rheumathoid Factor (RF)-positive polyarthritis in children and RF-positive RA in adults, whereas HLA-DRB1*08, HLA-DRB1*11, and HLA-DRB1*13 are strongest associated with RF-negative polyarthritis and oligoarticular JIA (42, 43).