Disorders affecting craniofacial development represent a large fraction of birth defects (1 ). The advent of transgenic and gene knockout technology has led to the identification of a variety of genes that have roles in craniofacial development. These technologies, together with the tools of human genetics, are being used to recreate specific human genetic defects in the mouse, providing an understanding of the pathophysiology of craniofacial disorders and laying the foundation for improvements in therapies.
