Due to the severity and rapid progression of the disease, the prognosis of anti-MDA5 Ab+ DM complicated by RPILD is poor, with a 90-day survival rate of 67% in Asia.[6] Although early diagnosis and treatment of anti-MDA5 Ab+ DM are important to improve patient outcomes, it is difficult to distinguish rapidly deteriorating abnormalities such as dyspnea, weakness, elevation of muscle enzymes, and pulmonary involvement associated with anti-MDA5 Ab+ DM from those caused by severe bacterial pneumonia. Here, IFIH1 is linked to dermatomyositis.