Consistent with the monocyte fraction changes analyzed according to MSA types (Supplementary Figure S2), the fraction of broad monocytes increased in the PBMCs of anti-MDA5+ (23.36% ± 13.11% vs. 15.82% ± 4.43%, p = 0.0009), anti-Jo-1+ (29.79% ± 9.82% vs. 15.82% ± 4.43%, p = 0.0089), and MSA- (21.17% ± 5.08% vs. 15.82% ± 4.43%, p = 0.0018) IIM patients (Supplementary Figures S2A–D). Here, IFIH1 is linked to acquired idiopathic inflammatory myopathy.