What is Treacher Collins Syndrome?
Treacher Collins syndrome, also known as mandibulofacial dysostosis, is a condition resulting from genetic problems. It impacts roughly one child in every 40,000 in both the United States and around the world. According to research, there are no connections between race and the disease. In addition, it is equally common in both males and females.
The disease impacts the gene TCOF1 located on chromosome 5 in human DNA. This gene is responsible for the treacle protein which stimulates the growth of facial and cranial features. If a problem occurs with the TCOF1 gene, this protein fails to survive long enough to create the full range of features common in the human craniofacial structure. This results in malformations in the eyes, mouth, ears and bone structure seen at birth.
Treacher Collins syndrome impacts individuals during the fetal developmental stage in the womb. Usually, onset takes place roughly six to seven weeks after conception. Genetic testing while the fetus is still in the womb can identify those who are at risk of being born with the disease.
Treacher Collins syndrome is generally passed from parent to child. If one parent has the genetic disorder, there is a 50 percent chance that it will be passed onto a child. Since the gene is a dominant gene, each pregnancy is at risk for the hereditary problem. However, just because one child is born with the condition, it does not necessarily mean a second child will suffer from the disease. If both parents carry the gene for Treacher Collins, there is nearly a 100 percent chance for the child to be born with the condition.
Mutations of the TCOF1 Gene
Approximately 60 percent of all cases of Treacher Collins syndrome are not caused by inheritance of the gene. These cases are simply caused by the natural mutation of the TCOF1 gene. Scientists have identified over 25 different ways in which the gene mutates, most involving either insertion or deletion in the coding. When a child is born with Treacher Collins syndrome, it is highly unlikely that a sibling will also suffer from a random mutation of chromosome 5.
Do Environmental Factors Cause the Condition?
There are no known environmental factors that cause the mutations resulting in Treacher Collins syndrome. Most geneticists simply believe that the condition is the result of natural progression, meaning the gene is subject to problems like most parts of human DNA. However, it has been shown that mutations to the TCOF1 gene is more common than most genes.
One study, conducted in 1983, showed that there was a connection between high levels of vitamin A and Treacher Collins syndrome. Scientists researching the phenomena injected numerous rats, hamsters, and mice with retinoic acid while offspring were in the womb. These animals had a higher prevalence of being born with facial skeleton deformities than other rats. Although the research identified a connection, there is little evidence to support the connection in humans.
“Mandibulofacial Dysostosis” eMedicine: https://emedicine.medscape.com/article/946143-overview
“Treacher Collins Syndrome” Cleft Palate Foundation: https://www.cleftline.org/publications/treacher_collins
Cleft Palate. (Supplied by Felsir at Wikimedia Commons; GNU Free Documentation License; https://upload.wikimedia.org/wikipedia/commons/2/21/Cleftbefore.jpg)
This post is part of the series: Facts About Treacher Collins Syndrome
Treacher Collins syndrome is a genetic condition caused by mutations to the TCOF1 gene found on chromosome 5. Treatment methods such as corrective surgery and education can aid children born with problems such as facial and cranial malformations.