FGFR1 and craniosynostosis: The importance of FGF signaling in human skull development has been revealed by the identification of gain-of-function mutations in the FGFR1, FGFR2, and FGFR3 genes in a number of craniosynostosis syndromes, such as Apert, Crouzon, Pfeiffer, and Muenke syndromes and Thanatophoric dysplasia17.