In our study, we demonstrate in a representative JSLE cohort (JSLE is up to 10 times rarer than adult-onset SLE) that there is a reduction in cytotoxic CD8+ T cells within the peripheral blood of JSLE patients compared to controls, irrespective of disease activity or treatment, which is due to a numerical defect in EM CD8+ T cells. This evidence concerns the gene CD8A and systemic lupus erythematosus.