Anti-melanoma differentiation-associated gene 5 antibody (anti-MDA5 Ab) was identified as an autoantigen associated with DM in 2009.[1] Anti-MDA5 Ab-positive (+) DM patients frequently exhibit clinically amyopathic dermatomyositis (CADM) and develop rapidly progressive interstitial lung disease (RPILD). The gene discussed is IFIH1; the disease is clinically amyopathic dermatomyositis.