Clinical features of Crouzon's syndrome patients with and without a positive family history of Crouzon's syndrome.

Crouzon's syndrome occurs in 1 in 25,000 live births and follows an autosomal dominant mode of transmission. However, 30 to 60% of cases are sporadic and represent fresh mutations. Previous reports involving large series of Crouzon's syndrome patients mixed sporadic and familial cases. In this article, the clinical features of 17 familial cases of Crouzon's syndrome were compared with another 27 sporadic cases. Furthermore, familial cases were studied to document (1) expressivity in members of the same family; (2) the skull base angle in unoperated members of the same family, and (3) the presence of germinal mosaicism. In familial cases of Crouzon's syndrome, craniosynostosis and proptosis were seen in 76% and 88% of patients, respectively. On the other hand, these two features were observed in 100% of sporadic cases. Variability of expression in members of the same family was a common finding. The cranial base angle was also variable in the affected members of the same family. In the series, germinal mosaicism was suspected in one family. Possible explanations for our findings are discussed as well as the implications of genetic mapping in Crouzon's syndrome.