Treacher Collins syndrome (mandibulofacial dysostosis) results from abnormal development of which pharyngeal arch?
- A Second pharyngeal arch (Reichert's cartilage)
- B Third pharyngeal arch giving rise to greater cornua of hyoid
- C First pharyngeal arch (Meckel's cartilage) and associated neural crest cells ✓
- D Fourth and sixth pharyngeal arches forming the laryngeal cartilages
Explanation
Treacher Collins syndrome (TCOF1 mutation in treacle protein) is a neural crest disorder specifically affecting migration and development of first pharyngeal arch neural crest cells, which form the mandible (Meckel's cartilage derivatives), zygomatic complex, temporal bone, and middle ear ossicles. The resulting phenotype includes malar hypoplasia, micrognathia, downslanting palpebral fissures, colobomata of lower eyelids, and malformed external ears. Second arch derivatives (stapes superstructure, styloid, lesser cornua of hyoid) and their associated nerves (CN VII) may also be affected in more severe forms.
Reference: BD Chaurasia's Human Anatomy, 8th ed.
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Written and medically reviewed by the StethoPrep medical team.