A single gene abnormality causes Treacher Collins syndrome. This gene is found on chromosome 5, and the normal function of the gene is unknown. More than 50 different changes in the gene have been associated with Treacher Collins syndrome. A recent study found that during embryonic development, an abnormally high level of cell death in cells called neural crest cells occurs in babies with Treacher Collins syndrome, leading to the facial abnormalities.

In more than half of cases, the gene mutation that causes Treacher Collins syndrome occurs spontaneously during embryonic development. There is no evidence that a mother’s lifestyle choices during pregnancy affect this mutation.

However, the Treacher Collins gene mutation is autosomal dominant, which means that if one parent has the mutation, they have a 1 in 2 chance of passing the mutation on to their child. A parent with Treacher Collins syndrome may have one normal gene and one altered gene. If the altered gene is passed on to a child, Treacher Collins syndrome can result. About 40 percent of people with Treacher Collins syndrome also have a parent with the syndrome, according to the National Craniofacial Association. Both males and females are affected equally by Treacher Collins syndrome.