Treacher-Collins syndrome is a condition that affects the development of bones and other tissues of the face. The signs and symptoms of this disorder vary greatly, ranging from almost unnoticeable to severe. Most affected individuals have underdeveloped facial bones, particularly the cheek bones, as well as a very small jaw and chin (micrognathia). Some people with this condition are also born with an opening in the roof of the mouth (cleft palate). In severe cases, underdevelopment of the facial bones may restrict an infant’s airway, resulting in respiratory challenges.