The heart in selected congenital malformations. A lesson in pathogenetic relationships.

The application of new knowledge on the pathogenesis of congenital heart defects has increased our understanding of associated, non-cardiac malformations seen in certain syndromes. Defects in the proliferation and migration of neural crest cells are thought to contribute to conotruncal defects. These are seen in association with conditions such as DiGeorge syndrome. CHARGE association, hemifacial microsomia, and Shprintzen syndrome. They also form part of the isotretinoin and thalidomide embryopathies. Their association with conotruncal defects suggests that abnormal migration of neural crest cells may play a role in the pathogenesis of these syndromes.