Introduction

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. 

Developmental Background

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. The external ear, the middle ear and the internal ear are deformed to some extent. In some situations, these structures are completely absent. Cleft palate can also occur if the palatal shelves have not fused Cleft lip is also a common feature. A patient of Mandibulofacial Dysostosis has a high palatal arch-giving rise to speech difficulties. The teeth are abnormally positioned and do not always relate to those in the opposing arch/bone resulting in malocclusion. Another striking feature of the disease is the presence of blind fistulas* between the angle of the mouth and the ears. There is unusual growth of hair converging towards the cheeks. This gives a fish like appearance to the face. 

It is theorized that Mandibulofacial Dysostosis occurs due to the failure of the maxillary mesoderm to develop beyond what is called the 50 mm stage of the embryo. This means that the trigger that spurs the development of the head and neck region is either faulty or completely absent. This theory is supported by evidence of teeth formation by the sixth week of fetal life. The teeth in the upper jaw are especially affected in this condition and are place in quite unusual positions. Sometimes they fail to erupt and are embedded in the bone itself. Patients with Mandibulofacial Dysostosis are prone to fracture quite easily because of the fragile nature of facial bones. Even a push could bruise the face quite easily. Because of the malformation of the ears, patients can also suffer from hearing loss. 

A syndrome called as the Goldenhar syndrome has similar features as the Mandibulofacial Dysostosis. It is also called as hemifacial microsomia, but occurs less frequently than MD. In Goldenhar syndrome, the defects are unilateral in distribution as against the bilateral features in MD and is postulated to occur due to the interruption in blood supply to the face. 

Diagnosis

A diagnosis of Mandibulofacial Dysostosis is made on clinical grounds and is confirmed by X-ray, which typically demonstrate the thin bones especially in the facial region. 

Treatment

There is no known treatment for Mandibulofacial Dysostosis. Any treatment is symptomatic and cosmetic and patients are known to live an otherwise normal life well into adulthood. Malocclusion and teeth problems would need dental correction.

FAQs

Which doctor should I consult for Mandibulofacial Dysostosis?
An oral surgeon is the best person to deal with this problem. Later on the services of a speech therapist and a cosmetic surgeon could also be required. 

Is MD hereditary? 
Yes, Mandibulofacial Dysostosis is inherited as a familial trait though the gene responsible which is yet to be identified. 

Is Mandibulofacial Dysostosis fatal? 
No, the disease is usually present in a mild form. Sometimes there is a complete absence of the eyelashes, which could be cosmetically uncomfortable.

Can Mandibulofacial Dysostosis be prevented?
If there is a family history of Mandibulofacial Dysostosis, genetic counseling before conception would prove useful.

What are the complications of Mandibulofacial Dysostosis?
There can be difficulty in speaking, chewing food, feeding. Visual problems and hearing loss are other complications. Breathing difficulties can occur in rare conditions when the nasal bones are small and underdeveloped.

(Do calcium supplements help in Mandibulofacial Dysostosis?
There is no evidence to indicate that calcium restores normal function although it has been tried in several forms.)