Treacher Collins syndrome
Also known as: Mandibulofacial Dysostosis; Treacher Collins–Franceschetti syndrome
Treacher Collins syndrome is a genetic condition that affects the development of bones and other tissues in the face. The severity of the syndrome varies widely amongst affected individuals.
Last reviewed October 2019 by Professor M Dixon, Professor of Dental Genetics, University of Manchester, Manchester, UK.
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Treacher Collins syndrome is characterised by a combination of the following features:
- eyes that slant down at the outer corners
- colobomas (notched lower eyelids)
- micrognathia (small lower jaw)
- cleft palate (see entry Cleft Lip and/or Palate)
- middle ear defects – the middle ear contains three small bones that transmit sound to the inner ear
- microtia (under-developed, malformed or missing ears)
- under-developed or missing cheekbones and side wall/floor of the eye socket
- small or obstructed nasal passages
- unusual hairline, with hair growing across the cheek like a sideburn.
Most children with the syndrome usually have some degree of hearing loss and those severely affected may have respiratory problems. Eye abnormalities may lead to an increased risk of eye infection and dental abnormalities may also occur. People with Treacher Collins syndrome usually have normal intelligence.
Mutations in the TCOF1 gene cause the condition. This gene makes a protein called treacle, which is believed to play a role in the development of bones and other tissues in the face of a developing baby. Mutations in POLR1C and POLR1D have been identified but these are thought to account for only a small proportion of cases of Treacher Collins syndrome.
A diagnosis will usually be made on the clinical features observed. X-rays may be needed to determine the extent of facial bone abnormality. Molecular testing of the genes implicated in Treacher Collins syndrome can confirm the diagnosis
There is no cure for Treacher Collins syndrome, treatment is designed to alleviate the symptoms a person with the syndrome will experience. It is important that hearing loss is identified early on as it can affect learning. Children will need a full audiological (hearing) assessment and may need to wear a conductive hearing aid or have implanted hearing aids. Speech and language therapy may be needed if speech development is slowing due to hearing difficulties.
For those children that have difficulty breathing, a tracheostomy (a hole into the trachea through the front of the neck) may be necessary. Corrective surgery may be needed for a cleft palate. Reconstructive surgery may also be offered to build up the cheekbones, correct the nose or an underdeveloped jaw or reconstruct the outer ear. Overcrowded teeth or malocclusion of the bite (where teeth don’t meet each other as they should) may require dental work.
In Treacher Collins syndrome, inheritance is autosomal dominant with variable expression. A very small portion (about 1%) is inherited in an autosomal recessive manner. Over half of cases are sporadic mutations (they arise without either of the parents being affected.)
Prenatal diagnosis can sometimes be performed by molecular (DNA) testing if the mutation in a family is known. For pregnancies known to be at risk of Treacher Collins syndrome, detailed ultrasound scanning may detect some of the condition’s features.
Treacher Collins Family Support Group
The Group is a Registered Charity in England and Wales No. 1006300. It provides information and support to families affected by first and second arch syndromes, atresia of the ear, and any other condition combining conductive deafness with facial or head malformation. The Group holds an annual family conference.
Group details last reviewed October 2019.