In our research work, we found that the JDM patients with anti-MDA5 antibodies have an earlier onset age than those without anti-MDA5 (6.78 ± 3.49y vs. 8.19 ± 3.28y, p = 0.017).The patients with anti-MDA5 showed higher rates of fever (55.3% vs. 32.5%, p = 0.012), alopecia (10.5% vs. 1.8%, p = 0.017), periungual telangiectasia (44.7% vs. 21.1%, p = 0.005), Gottron’s sign (92.1% vs. 74.6%, p = 0.022), ILD (78.9% vs. 34.2%, p< 0.00001), and arthritis (59.7% vs. 28.9%, p = 0.001). This evidence concerns the gene IFIH1 and Arthritis.