With this study, we propose to include anti-HMGCR autoantibody testing in the IIM diagnostic routine, applying to patients with phenotype of polymyositis, dermatomyositis, and, perhaps, some cases of asymptomatic hyper-CK-emia and myalgia (e.g., unclear cases resembling muscle dystrophies). The gene discussed is HMGCR; the disease is dermatomyositis.