TNNI3 and extrinsic cardiomyopathy: Previous studies have reported several risk factors for DCM (4, 5), including functional variants in target proteins [titin, cardiac troponin I (CTnI), and desmocollin-2]; the perinatal period; alcoholism; secondary cardiomyopathy due to autoimmune diseases [Behçet's disease and systemic lupus erythematosus (SLE)]; metabolic, endocrine, and nutritional diseases (hyperthyroidism and thyrotoxicosis, hypothyroidism, and carnitine metabolic disorder); and cardiomyopathy secondary to other organ diseases (uremia).