Mandibulofacial Dysostosis is a condition characterized by a number of head and neck defects owing to the malformation of these structures during the developmental stage. It is often referred to as Treacher-Collins syndrome, named after the scientists who discovered it. It is also called as the Franceschetti syndrome. Mandibulofacial Dysostosis is inherited as a dominant familial trait and is a part of a group of syndromes referred to as the "branchial arch syndromes" Branchial arches are developmental structures from which most of the head and neck structures are formed.
During the developmental stage, the embryo undergoes a series of transformations that form a template for the development of organs and processes. A group of such processes are responsible for the development of most of the structures involved in the head and neck the branchial arches. These are 6 in number, but essentially five of them are functional as the fifth arch is rudimentary. The first arch is called the mandibular arch and this is the main focus in Treacher Collins syndrome. Defects in this arch lead to the development of the syndrome in future.
Signs and Symptoms
Mandibulofacial Dysostosis is characterized by a wide variety of clinical features depending on the branchial arches involved in the developmental malformation. The first thing that is apparent on looking at a person affected by the condition is the presence of anti-mongoloid palpebral fissures and the partially absent eyelids. Sometimes the eyelashes are completely absent. There is a deficient growth in facial bones especially that of the mandible or the lower jaw and the malar bones, also called the cheek bones. This results in a narrow facial structure giving the patient a characteristic appearance referred to as the Parrot Beak appearance.