The role of Hox genes during organogenesis in mammals

The Hox gene family of transcription factors plays a critical role in the hierarchy of developmental processes. Gene targeting experiments have clearly demonstrated the importance of Hox genes in the correct patterning of axial and appendicular skeletons. Moreover, Hox genes are involved in several organogenesis processes. Nearly one third of the Hox mutations result. in a lethal phenotype, but in most cases, skeletal transformations cannot account for the lethality. In this article, we review the implication of Hox genes in organogenesis with a particular attention to the Hoxa5 gene.