CFNS is a rareX-linked disorder caused by mutations in the ephrin-B1 gene (EFNB1).1 CFNS predominantly affects the head,face and limbs and characterized by coronal craniosynostosis, frontal bossing,severe hypertelorism, craniofacial asymmetry, down slant palpebral fissure, broadnasal root, bifid nasal tip, grooved fingernails, curly wiry hair, and abnormalitiesof the thoracic skeleton.1Phenotypic expression varies greatly amongst affected individuals. The gene discussed is EFNB1; the disease is craniosynostosis.