The recent advances in molecular biology and genetic engineering are producing relevant results in cardiology, in particular in the field of cardiomyopathies. Molecular genetics has been used for the detection of viral genomes persisting in myocardial tissue of patients with idiopathic dilated cardiomyopathy (IDC). Very recent data, based on highly sensitive and specific technologies, suggest, however, that enterovirus persistence is not a major cause of the disease. Another application of molecular genetics is the study of the familial form of IDC, using linkage analysis as a tool for the identification of the disease gene. According to this method, the X-linked form of familial IDC has been mapped within the dystrophin gene in a series of families, and preliminary reports suggest that the mutation (or mutations) concerns the muscle-promoter region. Linkage studies on the autosomal dominant form of IDC are in progress. A possible approach is the identification of linkage between the disease and an array of "candidate genes". Preliminary data have ruled out the involvement of a series of relevant candidates genes, among which the cardiac beta-myosin heavy chain gene. An alternative approach for linkage studies is to perform a random screening of the genome, in which a large number of anonymous markers are selected and tested. In conclusion, molecular genetics is starting to provide fundamental data about the pathogenetic mechanisms of IDC. The relevance of these findings is also crucial for clinical and therapeutic implications.
