Monarch Disease Ontology identifier MONDO_0002457 (Treacher-Collins syndrome) is a congenital disorder of craniofacial development characterized by bilateral symmetrical oto-mandibular dysplasia without abnormalities of the extremities, and associated with several head and neck defects. Also known as: Franceschetti syndrome, Franceschetti-Klein syndrome, Treacher Collins Syndrome, Treacher Collins syndrome, mandibulofacial dysostosis without limb anomalies.