With regard to disease duration at diagnosis of PM/DM-associated ILD, the median disease duration (IQR) was significantly shorter in anti-MDA5 antibody-positive group: 2 months [1–3], than in anti-ARS antibody-positive group: 3 months (1–8) (P = 0.0002) or double-negative group: 3 months [1–6] (P = 0.0005). This evidence concerns the gene IFIH1 and interstitial lung disease.