Which finding is characteristic of Crouzon syndrome?

Correct answer: A. Midface deficiency

• A. CORRECT. Crouzon syndrome is a craniosynostosis caused by FGFR2 mutation. Premature fusion of the cranial and facial sutures arrests forward growth of the maxilla, producing MIDFACE DEFICIENCY (maxillary hypoplasia) with the associated exophthalmos from shallow orbits, hypertelorism, a beaked nose, and a relative mandibular prognathism that gives a Class III skeletal pattern with a concave profile. Anterior open bite and severe maxillary crowding are common dental findings.
• B. Macroglossia is seen in Beckwith-Wiedemann syndrome, Down syndrome (relative), hypothyroidism and amyloidosis.
• C. Micrognathia (a small mandible) is the hallmark of Pierre Robin sequence and Treacher Collins syndrome, not Crouzon. In Crouzon the mandible is normal but appears prognathic because the maxilla is deficient.
• D. Cleft palate is characteristic of Pierre Robin sequence, van der Woude and Stickler syndromes. It is not a defining feature of Crouzon, though a high arched or occasionally cleft palate can occur.

Note: Compare with Apert syndrome — also FGFR2, also midface deficiency, but distinguished by syndactyly of the hands and feet.