Congenital heart disease in patients with Down's syndrome: anatomic and genetic aspects.

The frequency of congenital heart disease in children with Down's Syndrome is high and ranges between 40 and 50% of cases. It was evident for many years that patients with trisomy 21 present certain congenital heart defects (atrioventricular canal, ventricular septal defect, tetralogy of Fallot) and seem to be "protected" from others (situs inversus and situs ambiguus, ventricular inversion, transposition of the great arteries). Recent observations also suggest that left-sided obstructive lesions and the muscular ventricular septal defect are very rare. The role of a suspected "increased adhesivanes of trisomy 21 cells" and of the anomalies of neutral crest needs to be investigated. The interaction between studies of clinicians and basic research will improve the knowledge of these genetically determined heart defects.