LATERALITY DISTURBANCES

One of the earliest, and most crucial, steps in cardiac morphogenesis is looping of the primitive heart tube. This process provides the spat ial context for all future steps in heart development, and defects in cardiac loop formation result in complex structural heart disease. Loo p formation is also one of the first visible asymmetries along the lef t-right body axis, and as such is dependent upon the development of th e entire embryonic left-right axis. Formation of the left-right body a xis is a developmental process, that, like the formation of the antero posterior and dorsoventral axes, is programmed by multiple genetic ste ps. It is also a process that is essential and unique to vertebrate de velopment. Therefore, an understanding of the development of left-righ t asymmetry at the genetic and molecular level will greatly aid in the understanding of the etiology of this complex group of congenital hea rt defects.