IFIH1 and rheumatoid arthritis: Although no significant differences in serum HB-EGF levels were observed among the four groups (HCs, IIM, SSc, and RA) (Figure 1A), serum HB-EGF levels of IIM patients with anti-Mi-2 antibodies were significantly higher compared with those of HCs and IIM patients with anti-MDA-5 antibodies (IIM patients with anti–Mi-2 antibodies: median, 183.7 pg/mL (IQR: 159.9–223.8); HCs: median, 74.8 pg/mL (IQR: 56.8–98.0), p = 0.045; IIM patients with anti-MDA-5 antibody: median, 63.1 pg/mL (IQR: 48.2–81.3); p = 0.021) (Figure 1B).