
<ArticleTitle>Classification of left-right patterning defects in zebrafish, mice, and humans.</ArticleTitle>
<AbstractText>Numerous genes and developmental processes have been implicated in the establishment of the vertebrate left-right axis. Although the mechanisms that initiate left-right patterning may be distinct in different classes of vertebrates, it is clear that the asymmetric gene expression patterns of <prot>nodal</prot>, <prot>lefty</prot>, and <prot>pitx2</prot> in the left lateral plate mesoderm are conserved and that left-right development of the brain, heart, and gut is tightly linked to the development of the embryonic midline. This review categorizes left-right patterning defects based on asymmetric gene expression patterns, midline phenotypes, and situs phenotypes. In so doing, we hope to provide a framework to assess the genetic bases of laterality defects in humans and other vertebrates.</AbstractText>
