The syndromic craniosynostoses, usually involving multiple sutures, are hereditary forms of craniosynostosis associated with extracranial phenotypes such as limb, cardiac, CNS and tracheal malformations. The genetic etiology of syndromic craniosynostosis in humans is only partially understood. Syndromic synostosis has been found to be associated with mutations of the fibroblast growth factor receptor family (FGFR1, -R2, -R3), TWIST1, MSX2, and EFNB1. Apert, Pfeiffer, Crouzon, and Jackson-Weiss syndromes are due to gain-of-function mutations of FGFR2 in either the Ig II-III linker region (Apert) or Ig III domain. Loss of function mutations of TWIST1 and gain-of-function mutations of MSX2 lead to Saethre-Chotzen and Boston-type syndromes, respectively. The mutations in Pfeiffer (FGFR1), Muenke (FGFR3), and Apert syndrome (FGFR2) are caused by the same amino acid substitution in a highly conserved region of the Ig II-III linker region of these proteins, which suggests that these receptor tyrosine kinases have an overlapping function in suture biology. In this review we will discuss the historical descriptions, current phenotypes and molecular causes of the more common forms of syndromic craniosynostosis.

Robinow syndrome (RS) is a rare genetic condition with two inheritance forms, autosomal dominant RS (DRS) and autosomal recessive RS (RRS). The characteristic features of this syndrome overlap in both inheritance forms, which make the clinical differential diagnosis difficult, especially in isolated cases. The objective of this study was to identify differences in the craniofacial and intraoral phenotype of patients with DRS and RRS. The characteristics and frequency of 13 facial and 13 intraoral clinical features associated with both DRS and RRS were assessed by direct dysmorphology examination and using a digital photographic analysis in 12 affected subjects. Although the phenotypic presentation varied and overlapped in the two forms of the syndrome, there were differences in the severity of the craniofacial and intraoral features. The craniofacial dysmorphology of RS was more severe in RRS. Nasal anomalies were the most frequent craniofacial features in both DRS and RRS. In contrast, intraoral features such as wide retromolar ridge, alveolar ridge deformation, malocclusion, dental crowding and hypodontia were more severe in patients with DRS. Overall, facial characteristics appeared less pronounced in adult subjects compared to younger subjects. Craniofacial and intraoral findings are highly variable in RS, with abnormalities of the intraoral structures being more prominent in the DRS form. We propose that the difference in the alveolar ridge deformation pattern and severity of other intraoral characteristics could enhance the differential diagnosis of the two forms of this syndrome.