Human Craniofacial Syndromes

Abstract

There are many syndromes which include craniofacial abnormalities. The defects may be restricted to specific regions of the head, for example the skull as occurs in craniosynostosis or specific regions of the face such as the first branchial arch as occurs in Treacher-Collins syndrome. In addition, as the heart and circulatory system also require cranial neural crest cells, the craniofacial abnormalities may be linked to cardiac and aortic arch defects reflecting the common origin of these structures as seen in DiGeorge syndrome. As neural and head development are interdependent, these syndromes may also be linked to neural defects. The most striking examples of these are exencephaly and holoprosencephaly, which were discussed in Sects. 2.1 and 2.2. In Table 5 we have summarised the human syndromes where the gene mutations responsible have been identified. In the following sections we describe three syndromes—Riegers, Treacher-Collins, and DiGeorge—where there has been a large advance of knowledge over the past few years in both the molecular and tissue bases of the syndrome.