In a group of familial TGA not associated with heterotaxy, we screened some genes that are known to be related to a subset of laterality defects and participate or cooperate in the Nodal signaling pathway, including Zic3, Acvr2B, LeftyA, CFC1, Nodal, Nkx2.5, and Creld1. We also screened the GATA4, which was previously found mutated in cases of dextrocardia [178], GDF1 [179] and FOXH1 [180], two genes linked to human CHDs, including TGA. Here, ZIC3 is linked to transposition of the great arteries.