Treacher Collins Syndrome

What is Treacher Collins syndrome?

Treacher Collins syndrome is a condition that affects the development of bones and other tissues in the face. The signs and symptoms of this disorder vary greatly, ranging from almost unnoticeable to severe. Most affected individuals have underdeveloped facial bones, which result in a sunken appearance in the middle of the face, a prominent nose, and a very small jaw and chin (micrognathia). Some people with this condition are also born with an opening in the roof of the mouth called a cleft palate. In severe cases, underdevelopment of the facial bones may restrict an affected infant's airway, causing potentially life-threatening respiratory problems.

People with Treacher Collins syndrome often have eyes that slant downward, sparse eyelashes, and a notch in the lower eyelids called a coloboma. This condition is also characterised by absent, small, or unusually formed ears (pinnae). Defects in the middle ear (which contains three small bones that transmit sound) cause hearing loss in about half of cases. People with Treacher Collins syndrome usually have normal intelligence.

How common is Treacher Collins syndrome?

This condition affects an estimated 1 in 50,000 people.

What genes are related to Treacher Collins syndrome?

Mutations in the TCOF1 gene cause Treacher Collins syndrome.

The TCOF1 gene provides instructions for making a protein called treacle. Although researchers have not determined the precise function of this protein, they believe that it plays a critical role before birth in the development of bones and other tissues in the face. Mutations in the TCOF1 gene prevent the production of functional treacle. It is unknown how a loss of this protein leads to the specific problems with facial development found in Treacher Collins syndrome.

How do people inherit Treacher Collins syndrome?

This condition is inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder. About 60 percent of cases result from new mutations in the TCOF1 gene. These cases occur in people with no history of the disorder in their family. In the remaining cases, a person with Treacher Collins syndrome inherits the altered gene from an affected parent.

What other names do people use for Treacher Collins syndrome?

• Franceschetti-Zwahlen-Klein syndrome
• Mandibulofacial Dysostosis
• MFD1
• Treacher Collins-Franceschetti syndrome