Familial dilated cardiomyopathy. Clinical and genetic characteristics.

Familial dilated cardiomyopathy (F-DCM) describes a clinically and genetically heterogeneous group of diseases, mostly inherited as autosomal dominant traits, having idiopathic left ventricular dilatation and dysfunction as a common phenotype. The age of onset, rate of progression, disease complications, as well as overall prognosis and outcome vary both amongst and within families. Clinical traits, both cardiac and extracardiac, may recur in association with the DCM phenotype. The former include conduction defects, structural abnormalities such as left ventricular noncompaction, of right ventricular involvement, and recurrence of atrial or ventricular arrhythmias; the latter commonly affect the musculoskeletal (myopathies/dystrophies, both clinically overt and subclinical), ocular, auditory, nervous, and integument systems. These traits may help guide genetic testing. In parallel to the clinical heterogeneity, F-DCM also shows genetic heterogeneity: more than 40 genes have been causally linked to F-DCM, with mutations recurring more commonly in a few known genes, and less frequently in rare, less commonly known genes. Based on the known prevalence of mutations in disease genes, more than 50% of F-DCM cases can be regarded as still genetically orphan, implying that further disease genes have to be discovered. Family screening and genetic testing are now established as the gold standard for diagnosis, care, and prevention in F-DCM. Diagnostic tests are performed using Sanger-based sequencing. Furthermore, new biotechnology tools, based on next-generation sequencing, are now being implemented in the research setting and will dramatically modify the future of the nosology of F-DCM.