PEDF and Chemerin plasma values were similar in ERA patients at diagnosis (PEDF: 13.1 ± 3.9 μg/ml, Chemerin: 108.6 ± 52.2 ng/ml) and controls (PEDF: 13.7 ± 2.4 μg/ml; p = ns; Chemerin: 95.2 ± 34.1 ng/ml; p = ns), while IL-6 plasma values were significantly higher in ERA patients than in controls (20.3 ± 34.5 pg/ml vs. 1.6 ± 3.8 pg/ml; p < 0.001). Here, RARRES2 is linked to enthesitis-related juvenile idiopathic arthritis.