Which of the following syndromes has mandibular hypoplasia at birth?

Correct answer: A. Pierre Robin sequence

• A. PIERRE ROBIN SEQUENCE is characterized by the triad: (1) MICROGNATHIA (mandibular hypoplasia at birth), (2) glossoptosis (posterior displacement of tongue due to small jaw), and (3) respiratory obstruction. The small mandible causes the tongue to fall back, obstructing the airway. A cleft palate may also be present.
• B. Down syndrome (trisomy 21) features a relatively normal-sized mandible with midface hypoplasia — true mandibular hypoplasia at birth is not the hallmark.
• C. Treacher Collins (mandibulofacial dysostosis) does feature mandibular hypoplasia, but it is more characterized by bilateral, symmetric ear deformities, downward-slanting palpebral fissures, and hearing loss. Pierre Robin more specifically features mandibular hypoplasia as the CAUSE of the other features.
• D. Crouzon syndrome features premature craniosynostosis, midface hypoplasia, and exophthalmos — but the mandible is typically normal in size. The MAXILLA is hypoplastic.