Craniosynostosis, the premature fusion of one or more sutures of the skull, is a common craniofacial anomaly, with an estimated incidence of 1/2000 to 1/3000 births.^1,2 Characteristic deformities of skull shape occur as a result of different patterns of sutural fusion, while compensatory skull expansion occurs at unaffected sutures to accommodate the growing brain. Premature fusion of the sagittal suture, for example, results in anterior to posterior elongation of the skull known as scaphocephaly.² Sagittal synostosis is the most common type of craniosynostosis, occurring in 40–58% of cases reported in large neurosurgical surveys, and shows a male predominance.^3–6 Most of the cases in these reports are “non-syndromic” instances of sagittal synostosis, while familial cases represent 2–9% of the total. Mental retardation is uncommon in isolated sagittal synostosis, but is more common in cases with associated malformations.^4–6 Over 90 syndromic forms of craniosynostosis have been described. Apert, Crouzon, Pfeiffer, Muenke, and Saethre–Chotzen syndromes are the most common of these, being classified according to the clinical involvement of the cranium, face, hands and feet, and other organs.² In these syndromes, brachycephaly or acrocephaly resulting from coronal synostosis is the predominant cranial deformity, and this is variably associated with mid-face hypoplasia, broad toes, syndactyly, and intellectual deficits. Sagittal synostosis is seen almost exclusively in combination with coronal synostosis,² while macrocephaly in the absence of craniosynostosis occurs infrequently.⁷ Familial scaphocephaly syndromes, which include Berant syndrome, “Philadelphia” type craniosynostosis, and Jones craniosynostosis,² are rare and their molecular aetiology remains unknown.

Mutations in five genes have been shown to cause various craniosynostosis syndromes. These are the transcription factor genes TWIST (Saethre–Chotzen syndrome, MIM 101400) and MSX2 (Boston-type craniosynostosis, MIM 604757), and three fibroblast growth factor receptor genes, FGFR1, FGFR2, and FGFR3 (Pfeiffer syndrome, …