When studying the PADI4 rs2240336 polymorphic locus, a borderline significance level tendency was observed for the increase of the proportion of the PADI4 rs2240336*GA genotype and the decrease of the proportion of the PADI4 rs2240336*GG genotype in JIA patients with the absence of the response to methotrexate (*GA: pcor = 0.053 and *GG: pcor = 0.053, respectively). Here, PADI4 is linked to juvenile idiopathic arthritis.