Erythropoiesis signature in a published cohort of healthy controls, and in patients with sJIA, bacterial infections, PAPA syndrome, and SLE. Gene-expression data published by Allantaz et al.  were retrieved from the Gene Expression Omnibus (GEO) database. Forty-nine probe sets were identical between the Affymetrix U133A (used by Allantaz et al.) and the U133 Plus 2.0 arrays (used by our group) and part of the erythropoiesis signature. The geometric mean of the linear expression values of these 49 probe sets was calculated for the individual samples, and the mean for the corresponding groups was calculated. (a) Comparison of the mean of the modified erythropoiesis indices according to the disease. (b) The mean of the modified erythropoiesis indices comparing sJIA with or without fever and with or without arthritis. (c) The mean of the modified erythropoiesis indices comparing patients with sJIA receiving or not receiving steroids, methotrexate, or infliximab. (d) Comparing the mean of the modified erythropoiesis indices according to disease, subdividing patients with sJIA into those with and those without fever. Horizontal bars indicate P < 0.05 (if comparing only two groups with Student's t test; if comparing more than two groups, ANOVA and post hoc Tukey testing).