Moreover, RA patients develop calpastatin autoantibodies, and their incidence is higher than in other patients with systemic autoimmune diseases, such as systemic lupus erythematosus (SLE, 27%), polymyositis/dermatomyositis (24%), systemic sclerosis (38%), and overlap syndrome (29%) [295,296]. This evidence concerns the gene CAST and systemic lupus erythematosus.