Idiopathic dilated cardiomyopathy. An immunologic, genetic, or infectious disease, or all of the above?

Third New International Dictio- nary defines "idiopathic" as "arising spontaneously or from an obscure or un- known cause." Medical diagnostic terminology has included this adjective for many years,' and its mys- terious nature has survived into the current era of sophisticated technology and molecular analyses. Id- iopathic dilated cardiomyopathy (IDC) is character- ized by increased left ventricular intracavitary dimen- sions, reduced systolic function, and, commonly, a congestive heart failure syndrome, but IDC is with- out a clear-cut etiology. Within the context of idiopathy, attempts have been made to associate IDC with various medical entities frequently connected to ill- nesses of obscure origin; for example, with autoim- munity and undiagnosable viral infections. In fact, numerous results indicating multiple immunologic defects have been generated from patients with IDC.