Mandibulofacial Dysostosis

Excerpt

Treacher Collins syndrome (also called mandibulofacial dysostosis) is a rare congenital disorder of craniofacial development that has variable phenotypic expression. Greater than 50% of cases are sporadic mutations, though familial cases are well-known. In familial Treacher Collins syndrome, the most common mode of inheritance is autosomal dominant, and TCOF1, POLR1C, and POLR1D gene mutations are the most commonly implicated.

The most common clinical manifestations include downward-slanting palpebral fissures, mandibular hypoplasia, and malar hypoplasia (and can manifest as Tessier clefts 6, 7, 8), coloboma of the lower eyelids, malformation of the auricular pinna (microtia), and middle ear deformities and associated conductive hearing loss. These clinical features are usually symmetrical and bilateral. Mouse studies utilizing teratogenic cis- or trans-retinoic acid have attributed Treacher Collins syndrome to abnormal development of the first and second branchial arches.

The syndrome was described by Berry (1889), Treacher Collins (1900), and Franceschetti and Klein (1949) ergo the names Berry’s syndrome and Franceschetti-Zwahlen-Klein syndrome are also used in older literature. Treacher Collins syndrome (TCS) is the more preferred modern eponym, as he definitively described the essential components of the condition. Franceschetti and Klein used the term mandibulofacial dysostosis to describe the clinical features, and as the modern literature eschews eponyms whenever possible, this has become a frequent descriptor.

The craniofacial anomalies in these patients can lead to airway obstruction, speech impairment, hearing loss, and feeding difficulties. These patients are best treated via an interprofessional team to coordinate the many facets of their care.