As a first attempt to address this knowledge gap, we have performed a genome-scale comparison of CD4+ T cell DNA methylation at over 27,000 CpG sites associated with over 14,000 genes in 14 children with active JIA (10 oligoarticular and 4 polyarticular) and 14 age- and sex-matched healthy control children. The gene discussed is CD4; the disease is juvenile idiopathic arthritis.