Treacher Collins syndrome is named after the man who described it. Treacher Collins syndrome is sometimes called Mandibulofacial Dysostosis. Mandibulofacial Dysostosis describes some of the features of this syndrome. Mandibulo refers to the lower jaw, and facial to the face. Dysostosis means that certain bones are not formed normally. The lower jaw and cheekbones are often smaller than usual (also known as mandibular hypoplasia and malar hypoplasia respectively).

Other possible features of Treacher Collins syndrome?

Treacher Collins syndrome is associated with lower eyelid coloboma, which means a small notch missing from the lower eyelid. About half of people with Treacher Collins syndrome are missing some eyelashes on the lower eyelid. Differences in the way the ear is formed, such as absence of the external auditory canal or microtia (small ear), ear tags (extra bits of skin in front of the ear) and little pits near the ear are common. Hearing loss of varying degrees may also occur. While it is unusual to have a cleft lip and palate with Treacher Collins syndrome, cleft palate alone is not an unusual finding occurring in about a third of people with Treacher Collins syndrome. Learning problems are not normally associated with Treacher Collins syndrome.

Will someone with Treacher Collins syndrome have all the feature of the syndrome?

No, this is a very variable condition. Some people may not even know that they have it unless they have a child with it. It is not possible for anyone to predict how many or how few of the possible features associated with Treacher Collins syndrome a person will have.

What causes Treacher Collins syndrome?

This condition is caused by a change in a single gene. The Treacher Collins syndrome gene is on chromosome 5. At the present time it is not known what the correct function of this gene is. Over 50 different changes in the gene are known to cause Treacher Collins syndrome.

Can more than one person in a family have Treacher Collins syndrome?

In about 60% of people with Treacher Collins syndrome the change in their gene happened for the first time in them. This means that there is little chance of this person’s parents or brothers or sisters having any children with Treacher Collins syndrome.

In about 40% of people with Treacher Collins syndrome one of their parents also has the same gene chance. Treacher Collins syndrome is an autosomal dominant condition. If you have Treacher Collins syndrome, there is a 1 in 2 or 50% chance for each pregnancy that your child will also have Treacher Collins syndrome. This is because a parent with Treacher Collins syndrome has one normal Treacher Collins gene and one changed gene. When you have a baby you only pass on one of each pair of your gene. If you pass on the normal gene, then the baby will not have Treacher Collins syndrome; if you pass on the gene with a change, the child will have Treacher Collins syndrome.

You have no control over which gene you pass on. It is like flipping a coin. You could get all heads, all tails or a mixture.

Is there a test for Treacher Collins?

There is a clinical test available. This test is very labor intensive.


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  • Jones K.L., Smith’s Recognizable Patterns of Human Malformation. 5th Edition. W.B. Soliders Company A Division of Harcourt Brace and Company, 1997.
  • Online Mendelian Inheritance in Man, OMIM (TM). Johns Hopkins University, Baltimore, MD. MIM Number: 154500: 2002.