Interrelationship of Cranial Suture Fusion, Basicranial Development, and Resynostosis Following Suturectomy in Twist1^+/− Mice, a Murine Model of Saethre-Chotzen Syndrome

The interrelationships among suture fusion, basicranial development, and subsequent resynostosis in syndromic craniosynostosis have yet to be examined. The objectives of this study were to determine the potential relationship between suture fusion and cranial base development in a model of syndromic craniosynostosis and to assess the effects of the syndrome on resynostosis following suturectomy. To do this, posterior frontal and coronal suture fusion, postnatal development of sphenooccipital synchondrosis, and resynostosis in Twist1^+/+ (WT) and Twist1^+/− litter-matched mice (a model for Saethre-Chotzen syndrome) were quantified by evaluating μCT images with advanced image-processing algorithms. The coronal suture in Twist^+/− mice developed, fused, and mineralized at a faster rate than that in normal littermates at postnatal days 6–30. Moreover, premature fusion of the coronal suture in Twist1^+/− mice preceded alterations in cranial base development. Analysis of synchondrosis showed faster mineralization in Twist^+/− mice at postnatal days 25–30. In a rapid resynostosis model, there was an inability to fuse both the midline posterior frontal suture and craniotomy defects in 21-day-old Twist^+/− mice, despite having accelerated mineralization in the posterior frontal suture and defects. This study showed that dissimilarities between Twist1^+/+ and Twist1^+/− mice are not limited to a fused coronal suture but include differences in fusion of other sutures, the regenerative capacity of the cranial vault, and the development of the cranial base.