The developmental background of common arterial trunk still remains to be elucidated. In this anomaly both the coronary, systemic and pulmonary circulation arise from a common arterial stem with a common orifice. The contribution of the embryonic ectomesenchymal neural crest seems to be essential for a normal separation of the aorta, pulmonary trunk and the adjoining myocardium lined outflow tract. Experimental neural crest ablation studies in chicken have proved that there is a role for neural crest cells. Several molecular biological studies, however, have shown that we are not solely dealing with the influence of neural crest. Many genes and gene cascades have been manipulated in mice and have shown that e.g. the endothelin cascade, Foxc1 and Foxc2, and more recently Sema3C and neuropilin-1 are factors, that if disturbed, can lead to common arterial trunk often in combination with aortic arch anomalies such as interruption type B. In humans common arterial trunk is one of the characteristics of the 22q11 deletion syndrome. In the mouse several of these genes, located on the syntenic chromosome 16 have been studied for this effect, but most result in an embryolethal phenotype. Neural crest tracing studies in both chicken-quail chimeras and transgenic neural crest reporter mice have revealed that there is a difference in neural crest contribution to the aortic and pulmonary truncal wall. The orifice of the common arterial trunk reflects this finding in that the often abnormally high positioned coronary orifices reside in the aortic part of the orifice. Combining current data the common denominator for common arterial trunk seems to be a defective interaction of neural crest, endothelial cells and the surrounding mesenchyme. Disturbances of genes in any of the three cell types can lead to the malformation.

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Progress in Pediatric Cardiology
Department of Cardio-Thoracic Surgery

Gittenberger-de Groot, A.C, Bartelings, M.M, Bogers, A.J.J.C, Boot, M.J, & Poelmann, R.E. (2002). The embryology of the common arterial trunk. Progress in Pediatric Cardiology, 15(1), 1–8. doi:10.1016/S1058-9813(02)00002-4