Rotation and asymmetric development of the zebrafish heart requires directed migration of cardiac progenitor cells.A Nodal-independent and tissue-intrinsic mechanism controls heart-looping chiralityDominant-negative ALK2 allele associates with congenital heart defects.Bmp and nodal independently regulate lefty1 expression to maintain unilateral nodal activity during left-right axis specification in zebrafishBmp signaling exerts opposite effects on cardiac differentiationALK2 mutation in a patient with Down's syndrome and a congenital heart defectTransmembrane protein 2 (Tmem2) is required to regionally restrict atrioventricular canal boundary and endocardial cushion developmentGenes in congenital heart disease: atrioventricular valve formation.