Systemic JIA (sJIA) is distinct from other forms of chronic inflammatory arthritis in childhood due to its prominent systemic symptoms at disease onset, including fevers, rashes, and strikingly elevated inflammatory markers. Patients with sJIA may develop chronic debilitating arthritis, life threatening macrophage activation syndrome (MAS), and/or progressive lung disease (LD). The underlying biology and genetic risk factors that drive disease differences in sJIA is poorly understood. The STARS project will collect biosamples from children with sJIA to help us identify genetic variations that causes or contributes to the disease. In addition, we look to estimate the association between genetic variants and incidence of lung disease and test if this association is modified by medication use.