Left-Right Axis Determination of the Body and Heterotaxy Syndrome

Abstract

Congenital heart diseases (CHD) result from abnormal development of the cardiovascular system and usually involve defects in specific steps or structural components of the developing heart and vessels. The determination of left-right patterning of our body proceeds as following steps: 1) A number of motile cilia in the node rotate and lead to the unidirectional leftward flow of extra-embryonic fluid in the node cavity, 2) This “Nodal Flow” induces asymmetric expression of Nodal, a member of TGF-β superfamily, only on the left side of the embryo that eventually activates the molecular pathway regulating the left-side specific morphogenesis. Disruption of any of these steps may result in left-right patterning defects or heterotaxy syndrome in human. Discovery of numerous factors involving the components of monocilia in the node and left side specific molecular pathway has provided new insights into not only heterotaxy syndrome but also associated CHD.