[Epidemiology and genetics of congenital heart diseases and cardiomyopathies in children].

The incidence of congenital heart defects (CHD) is close to 1% of live birth. A high proportion of CHD is associated with chromosomal anomalies. A precise assessment of the phenotype is necessary to determine which type of chromosomal anomaly has to be identified: trisomy 21 in atrio-ventricular septal defect, deletion of chromosome 22q in conotruncal defects. Genetic heterogeneity of CHD has been proven for a wide range of defects. Phenotype-genotype correlations have been established and may be helpful to orient molecular investigations. In isolated CHD, very genes have been identified so far and the risk of recurrence in a family relies mainly on a statistical approach rather than on a molecular diagnosis. Cardiomyopathies (CM) in children are mostly secondary to CHD, myocardial ischemia, drug toxicity, viral infections, and rhythm disturbances. CM associated with genetic anomalies are seen in syndromes such as the Noonan's syndrome, in dominant familial forms and in metabolic diseases. For these latter, extensive investigations are necessary as they are responsible for 15% of CM in children younger than 2 years. They are mainly represented by lysosomal storage diseases and defects in fatty acid oxidation or respiratory chain.