HLA-DRB1 and juvenile idiopathic arthritis: Systemic JIA is considered an autoinflammatory disease with little genetic overlap with the other JIA subtypes.49 However, it has been shown that systemic JIA has strong genetic signals from the HLA class II molecule encoded by HLA-DRB1*11, confirming the role of the adaptive immune system.50 To test this, we statistically imputed HLA-DRB1*11 risk alleles using HIBAG V.1.2051 52 in the three cohorts, tested the predictive power of these genotypes, and compared them with our systemic JIA GRS in CHOP and CLARITY (online supplementary table S6).