Crouzon syndrome: a genetic disorder that prevents the skull from growing normally and leads to an abnormal shape of the head and face. Premature fusion of certain skull bones (craniosynostosis) during development causes the abnormality. Signs of Crouzon syndrome include wide-set, bulging eyes, vision problems, shallow eye sockets, eyes that point in different directions (strabismus), a beaked nose, and an underdeveloped upper jaw. Other symptoms can include hearing loss and tooth problems. Mutations in a gene known as FGFR2 cause Crouzon syndrome. The genetic defect is inherited in an autosomal dominant pattern, meaning one copy of the defective gene (from either parent) is sufficient to cause the condition. Also known as craniofacial dysarthrosis, craniofacial dysostosis, Crouzon disease, or Crouzon craniofacial dysostosis.