Japanese reports of anti-MDA5 Ab-positive DM patients demonstrated the following prevalences: CADM, approximately 80%; ILD, approximately 90%; RPILD, approximately 70%; and mortality, approximately 30%–50%,[3,9–13] indicating anti-MDA5 Ab-positive DM patients have poor prognoses. This evidence concerns the gene IFIH1 and clinically amyopathic dermatomyositis.