[Dilated cardiomyopathy: etiology, clinical criteria for diagnosis and screening of the familial form].

: Dilated cardiomyopathy (DCM) is a heart muscle disease characterized by impaired contractility and dilation of the left ventricle or both ventricles. In a large proportion of patients, the cause of the disease is unknown and DCM is considered to be the final common phenotype of a heterogeneous group of disorders. Molecular studies carried out in specific DCMs have identified several metabolic and structural defects leading to a common phenotype of myocardial damage. Viral infection and autoimmune disorder can cause DCM. However, a familial trait is present up to 50% of cases, indicating a major role of genetic factors. The analysis of the phenotype, the pattern of genetic transmission, and molecular genetic findings have allowed the characterization of different forms of familial DCM, suggesting genetic heterogeneity. Furthermore, the risk of disease has been estimated as high as 20% in relatives of familial DCM patients, which is significantly higher than the normal population. Taking into account that DCM can be clinically not evident due to its low penetrance (in particular in the young population), a reproducible and reliable method for the diagnosis of familial forms is critical in the management of the disease. To address this issue, consensus guidelines for the diagnosis and screening of familial DCM have been developed. The screening method for familial DCM is based on physical exam, electrocardiogram, and echocardiogram of first-degree relatives of affected subjects. The family screening should be followed-up every 2 to 3 years, in particular in unaffected relatives (in the absence of a molecular diagnosis), to exclude a late onset of the disease.