Treacher Collins syndrome (TCS), also known as Treacher Collins–Franceschetti syndrome or mandibulofacial dysostosis is a rare autosomal dominant congenital disorder characterized by craniofacial deformities, such as absent cheekbones.:577 Treacher Collins syndrome is found in about 1 in 50,000 births. The typical physical features include downward slanting eyes, micrognathia (a small lower jaw), conductive hearing loss, underdeveloped zygoma, drooping part of the lateral lower eyelids, and malformed or absent ears.
