Q: My neighbor just had the most adorable baby, and she was diagnosed with Treacher Collins syndrome. What is that?A: Treacher Collins syndrome (TCS) is a genetic disorder that affects about one in every 25,000 to 50,000 births in the United States. It affects males and females, and all races, essentially equally.TCS, also called mandibulofacial dysostosis, is a disorder that affects the development of the bones and other tissues of the face and head.