RESUMEN
Congenital cardiovascular malformation is a common birth defect incorporating abnormalities of the outflow tract and aortic arch arteries, and mice deficient in the transcription factor AP-2α (Tcfap2a) present with complex defects affecting these structures. AP-2α is expressed in the pharyngeal surface ectoderm and neural crest at mid-embryogenesis in the mouse, but the precise tissue compartment in which AP-2α is required for cardiovascular development has not been identified. In this study we describe the fully penetrant AP-2α deficient cardiovascular phenotype on a C57Bl/6J genetic background and show that this is associated with increased apoptosis in the pharyngeal ectoderm. Neural crest cell migration into the pharyngeal arches was not affected. Cre-expressing transgenic mice were used in conjunction with an AP-2α conditional allele to examine the effect of deleting AP-2α from the pharyngeal surface ectoderm and the neural crest, either individually or in combination, as well as the second heart field. This, surprisingly, was unable to fully recapitulate the global AP-2α deficient cardiovascular phenotype. The outflow tract and arch artery phenotype was, however, recapitulated through early embryonic Cre-mediated recombination. These findings indicate that AP-2α has a complex influence on cardiovascular development either being required very early in embryogenesis and/or having a redundant function in many tissue layers.
RESUMEN
Interrupted aortic arch is a rare condition with typical presentation within the first few weeks of life, as the circulation is dependent upon patency of the arterial duct. Most cases are associated with intracardiac anomalies, the most common being a ventricular septal defect with some degree of hypoplasia and/or obstruction of the left ventricular outflow tract. Presentation beyond infancy is uncommon, and suggests the presence of well-developed collateral circulation. This case of childhood presentation of interrupted aortic arch and intact ventricular septum highlights the very unusual finding of bilateral collateral arteries consistent with persistent carotid ducts. Cardiac MRI angiography with three-dimensional reconstruction defined not only the site of interruption in the aortic arch but also the entire collateral circulation.