In the last century, autoantibodies [Immune-Mediated Necrotizing Myopathy (IMNM) and Dermatomyositis (DM)] and CD8+ T cell-induced cytotoxicity [Polymyositis (PM) and Inclusion Body Myositis (IBM)] were the primarily the only two recognized etiopathologies used to classify myopathies [1–3]. This evidence concerns the gene CD8A and inclusion body myositis.