Left-right axis malformations in man and mouse.

The study of left-right axis malformations in man and mouse has greatly advanced understanding of the mechanisms regulating vertebrate left-right axis formation. Recently, the roles of the TGF-beta family, Sonic hedgehog and fibroblast growth factor signaling, homeobox genes, and cilia in left-right axis determination have been more clearly defined. The identification of genes and environmental factors affecting left-right axis formation has important implications for understanding human laterality defects.