IFIH1 and dermatomyositis: Moreover, serum ferritin (SF) was markedly increased in anti-MDA5+DM group (n = 39) as compared with those in ASS group (n = 20) (916.94 ± 771.48 vs. 258.20 ± 156.77 ng/mL, p = 0.001) (Table 1).