Sox9 function in craniofacial development and disease

The Sox family of transcriptional regulators has been implicated in the control of a broad array of developmental processes. One member of this family SOX9 was first identified as a candidate gene for campomelic dysplasia (CD), a human syndrome affecting skeletal, and testis development. In these patients most endochondral bones of the face fail to develop resulting in multiple defects such as micrognathia, cleft palate, and facial dysmorphia. In this review we describe Sox9 expression during embryonic development and summarize loss of function experiments in frog, fish, and mouse embryos highlighting the role of Sox9 in regulating morphogenesis of the face. We also discuss the mutations in and around SOX9 responsible for craniofacial defects in CD patients.