IFIH1 and polymyositis: Rapidly progressive ILD was found in 17 % of the patients in this study.3 In a study of 76 Italian patients with dermatomyositis/polymyositis, anti MDA5 antibody was detected in 5 patients by immunoprecipitation and all 5 patients had clinically amyopathic dermatomyositis with typical dermatomyositis skin lesions.