Children with Treacher Collins Syndrome (mandibulofacial dysostosis) exhibit severe malar and mandibular hypoplasia. They have charecteristic downward – slanting , palpebral fissures and colobomata of the loweral lip. Severe external , middle, and inner ear malformations can occur with concomittant and conductive hearing loss. Approximately one third of the patient have a cleft palate.
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. Treacher Collins syndrome is found in about one 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.
The presentation of symptoms in people with Treacher Collins syndrome varies. Some individuals may be so mildly affected, they remain undiagnosed; others can have severe facial involvement and life-threatening airway compromise. Most of the features of TCS are bilateral and are already recognisable at birth.
Patients are mostly characterized by these abnormalities:
- Hypoplasia of the facial bones: Most described is an underdeveloped mandibular and zygomatic bone. This leads to a small and malformed jaw. Mandible hypoplasia can result in a malocclusion.
- Ear anomalies: The external ear anomalies consist of small, rotated, or even absent auricles. Also symmetric, bilateral stenosis or atresia of the external auditory canals is described. In most cases, the ossicles and the middle ear cavity were dysmorphic. Inner ear malformations are rarely described. As a result of these abnormalities, a majority of the individuals with TCS have conductive hearing loss.
- Most patients experience eye problems, varying from colobomata of the lower eyelids and aplasia of lid lashes to short, down-slanting palpebral fissures, and missing eyelashes. Vision loss can occur and is associated with strabismus, refractive errors, and anisometropia.
- Cleft palate
- Airway problems, which are often a result of mandibular hypoplasia, can occur.
The presence of an abnormally shaped skull is not distinctive for Treacher Collins syndrome, but brachycephaly with bitemporal narrowing is sometimes observed.
Dental anomalies are seen in 60% of TCS patients. These anomalies consist in tooth agenesis (33%), enamel disformaties (20%), and malplacement of the maxillary first molars (13%). In some cases, dental anomalies in combination with mandible hypoplasia result in a malocclusion. This can lead to problems with food intake and the ability to close the mouth.
Some features related to TCS are seen less frequently:
- Nasal deformity
- High-arched palate
- Coloboma of the upper lid
- Ocular hypertelorism
- Choanal atresia
- Preauricular hair displacement
Facial deformity is still associated by the general public with developmental delay, and lesser intelligence, but intelligence of patients with TCS is usually normal. The psychological and social problems associated with facial deformity may affect quality of life in a number of patients.