Mandibulofacial dysostosis (Treacher Collins syndrome) is a rare genetic disorder characterized by craniofacial abnormalities of varying degree, including hypoplastic or absent zygomatic malar complex that results in periocular changes with downward-slanting palpebral fissures. Lower eyelid colobomas may also be present. Mandibular hypoplasia causes micrognathia with the characteristically small chin and lower jaw. Abnormalities of the external and middle ear are also found, manifesting as absent, small, or malformed ears and conductive hearing loss.