Anti-MDA5 was originally characterized in Japan in DM patients with hallmark cutaneous features and no proximal muscle weakness and termed clinically amyopathic DM (CADM).
Anti-MDA5 were originally identified in a clinically-defined subset of DM patients whose disease was expressed predominately in the skin for unusually long periods of time without accompanying muscle weakness [i.e., "clinically-amyopathic DM" (CADM)] and were at risk for acute, rapidly-progressive form of interstitial lung disease (ILD).