The teratogenic effects of a bis(dichloroacetyl)diamine on hamster embryos. Aortic arch anomalies and the pathogenesis of the DiGeorge syndrome.

A study of the teratogenic effects of Fertilysin, a bis(dichloroacetyl)diamine, on hamster embryos was undertaken for a comparison of Fertilysin-induced malformations with the DiGeorge syndrome of human patients, a rare birth defect characterized by thymic and parathyroid gland agenesis, abnormal facies, and aortic arch malformations. In treated hamsters, malformations of the aortic arches were found to be consistently produced, and many of these anomalies could not be explained by conventional methods of analysis. A pathogenetic scheme to classify malformations of the aortic arch and great vessels is offered, including a revision of Celoria and Patton's classification of interrupted aortic arches. It is suggested that the DiGeorge syndrome is a syndrome of truncated pharyngeal arch development with two general forms: 1) agenesis of or incomplete development of the sixth pharyngeal arch with pulmonic circulation through the fifth arch; 2) agenesis of or incomplete development of the fifth and sixth pharyngeal arches with pulmonic circulation through the fourth arch. The third aortic arch may descend into the thorax under these circumstances.