Patient with downslanted palpebral fissures, eyelid coloboma, and underdeveloped zygoma/mandible u2014 diagnosis:

Treacher Collins syndrome (mandibulofacial dysostosis) features downslanted palpebral fissures, eyelid coloboma, microtia, and underdeveloped zygoma, maxilla, and mandible u2014 due to inadequate neural crest cell migration to pharyngeal arches 1 and 2. Down syndrome has UPslanted fissures.