Our objective was to evaluate the prevalence and clinical manifestations of anti-MDA5-positive patients in a large cohort of DM patients from a single center in Barcelona, and to determine the feasibility of detecting this autoantibody with the use of more widely available techniques (ELISA and immunoblotting) with commercially available recombinant MDA5 as the antigen. This evidence concerns the gene IFIH1 and dermatomyositis.