Zygoauromandibular Dysplasia (Treacher Collins Syndrome)

What is Zygoauromandibular Dysplasia?

Zygoauromandibular dysplasia, more commonly referred to as Treacher Collins syndrome (TCS), is a rare condition that affects the development of tissues and bone in the face.

Caused by a genetic mutation, it’s estimated that Treacher Collins syndrome affects one in 50,000 individuals. While it can be inherited, the condition may also result from a new gene mutation that’s entirely random.

What are the Symptoms of Zygoauromandibular Dysplasia?

Named after English surgeon Edward Treacher Collins, TCS is caused by an abnormality in the TCOF-1 gene that results in a reduced amount of a specific protein (treacle) thought to play a role in facial bone development. Visible signs of Treacher Collins syndrome can range from subtle to severe.

Affected individuals may display the following characteristics:

  • Unusually formed, small, or absent ears
  • Cleft palate or a restricted airway
  • Eyes slanting downward
  • Underdeveloped facial bones
  • Small chin or jaw (micrognathia)
  • Notch in lower eyelids (coloboma)

Diagnosis of Treacher Collins Syndrome

When the condition is suspected from physical appearance, related testing often includes X-rays, CT scans, and MRIs to determine the extent of the irregular development. An orthopantomogram of the upper and lower jaw is sometimes performed. Testing is also done to rule out conditions that can produce similar abnormalities, such as Goldenhar syndrome.

What are the causes of Zygoauromandibular Dysplasia?

The condition is the result of mutations of the TCOF1 or POLR1D gene. Unfortunately, it is considered autosomal dominant, which means that only one copy of the altered gene is needed for the condition to be caused. About 60% of the known cases are from families that have no history of the condition.

In the remainder, there is a family member or family members who have the condition. Where parents have copies of the gene, most of them do not display any symptoms of the condition.

How is a Zygoauromandibular Dysplasia Treated?

Treatment typically involves corrective surgery performed in stages. For instance, cleft palate repair normally takes place between the ages of 9-12 months. Surgery needs to be timed to be performed in accordance with normal facial development stages to allow for growth-related changes affecting soft tissues and bones.

Treatments may also include:

  • External ear reconstruction
  • Speech therapy to address language and speech difficulties
  • Nose reconstruction

People with Treacher Collins syndrome sometimes experience vision and hearing problems due to under-developed bones around the eyes and ears. Related dental abnormalities may cause difficulties with food intake. The condition has no connection to or affect on intellectual development.

Can Zygoauromandibular Dysplasia be prevented?

There is currently no known cure for zygoauromandibular dysplasia. Likewise, there is no known preventive measures for the condition. Treatment for those suffering from the condition is limited to the specific needs of the patient, whether they be a child or an adult. When these treatments are performed, they are usually undertaken by a multidisciplinary team of craniofacial specialists.

One of the most important concerns, especially for infants, is their ability to breathe, which most often calls for special positioning of the airway to help with respiration. Hearing loss is also a common problem for those suffering from zygoauromandibular dysplasia. Hearing aids, often accompanied by speech therapy and educational intervention are the most common treatments.

There are some genetic therapy options being studied which might eventually prevent the condition. This includes, most commonly, the activation of certain genes as well as the deactivation of others that would cause the condition.

Last Reviewed:
October 11, 2016
Last Updated:
September 03, 2017
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