In the Ueda et al. report (2017), 3 out of 34 NS patients (9%) and 6 out of 18 CFC patients (33%) had craniosynostosis, and craniosynostosis affected all patients with mutations in KRAS. This strong genotype-phenotype association suggests specific mechanisms of pathology, worthy of investigation. This evidence concerns the gene KRAS and cardiofaciocutaneous syndrome.