[Genetic diagnosis of familial dilated cardiomyopathy].

The definition of familial dilated cardiomyopathy (DCM) is clinically based on the presence, in the same family, of at least two members proven as affected. The prevalence of familial forms is about 25-30%. The approach to define the prevalence of familial diseases and to identify asymptomatic subjects is based on a clinical, non-invasive screening of family members of consecutive index patients. Familial DCM is commonly inherited as autosomal dominant trait; less frequently it is autosomal recessive, X-linked or matrilinear. The disease is clinically and genetically heterogeneous. Genes causally linked to this phenotype include dystrophin, dystrophin-associated glycoproteins, actin, desmin, beta-miosin heavy chain, cardiac troponin T, and mitochondrial DNA genes, mostly transfer RNAs. A peculiar phenotype is DCM associated with atrioventricular block, an autosomal dominant disorder that is causally linked to lamin A/C gene defects in a high proportion of cases. Although the knowledge on molecular genetics of DCM is progressively increasing, at present, the number of molecular diagnoses that can be provided to patients is limited to a few X-linked, autosomal dominant and matrilinear DCMs (overall, about 10% of DCMs). The new clinical approach to familial DCM studies, based on the screening of family members, will bring to the cardiologist's attention both patients and relatives, with extension of the clinical evaluation to subjects who are still healthy. On the other hand, molecular genetists will face a complex molecular field, for both high heterogeneity and poor phenotypical specificity. Therefore, interdisciplinary clinical and research projects are especially needed, hopefully coordinated by scientific societies.