The aim of our study is to compare the dental arch dimensions of patients with Muenke syndrome and Saethre-Chotzen syndrome or TCF12-related craniosynostosis patients to those of a control group of healthy Dutch children, to investigate whether their jaw sizes are systematically smaller and whether the intermaxillary relationships of patients with Muenke and Saethre-Chotzen syndromes or TCF12-related craniosynostosis differ compared to those of the Dutch controls. This evidence concerns the gene TCF12 and Muenke syndrome.