Overview of Treacher Collins Syndrome

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Treacher Collins syndrome, also known as mandibulofacial dysostosis, is a rare disease that affects facial bone development, causing major facial deformities. Children afflicted with the syndrome can have a very unusual facial appearance. It affects approximately one in 50,000 people worldwide. 

Because it is so uncommon, the condition is not well known outside the medical community. A central character in a 2017 Hollywood movie, Wonder, was afflicted with Treacher Collins syndrome, which subsequently increased awareness and interest in the condition. 

Symptoms 

There can be some variability in the severity of Treacher Collins syndrome. The most prominent feature of the condition is its affect on facial appearance. The bone deformities can also cause impaired hearing, and facial bone malformations can result in deficiencies of smell or vision as well. Problems with airway structure may interfere with breathing. 

The altered facial development of Treacher Collins syndrome is apparent at birth, and, in some instances, it can be recognized even before birth on a prenatal ultrasound.

Other symptoms, such as hearing, vision, and smell deficits, may be less noticeable during infancy. Breathing difficulties can begin during infancy or may develop later in life. Treacher Collins syndrome does not typically affect intelligence, but the severe facial deformities can interfere with normal socializing and peer interactions, which can affect school attendance. 

The symptoms of Treacher Collins Syndrome include:

Changes in facial appearance: Treacher Collins syndrome is characterized by a small jaw and chin (micrognathia), a very thin and elongated face, and small, sunken cheekbones. The facial features are usually almost symmetrical.

Abnormal Eye Appearance: The small cheekbones result in a downward slant of the eyes, which can appear to be set back into the face. A characteristic notch that appears like a missing piece of skin on the eyelids is called an eyelid coloboma. If the shape of the eyes and the bone structure around eyes is severely affected, it may result in a visual deficit. Eyelashes are thin, often causing dry eyes.

Cleft palate: A cleft palate may be present as well. This is a defect in the bone that normally separates the roof of the mouth from the nasal passages above it. Children with a cleft palate have an open space between the roof of the mouth and the nose. This defect can allow food to enter into the nose, and potentially into the lungs, causing an infection. It may also allow mucus to enter into the mouth. 

Ear and hearing problems: Among the obvious changes in appearance, the ears can be small or unusually shaped. The bones of the ear canal, which cannot be seen easily without an ear examination, can be underdeveloped as well. This results in auditory (hearing) deficits. Rarely, the ears may be completely undeveloped, resulting in complete deafness. 

Respiratory problems: As a child’s face grows and develops, the facial bones may block the airway. At any point during life, respiratory problems may develop and can even be life-threatening if left untreated.

Problems with the sense of smell: Abnormalities in the development of the nasal passages and bone structure of the nose can affect smell sensation. 

Hand deformities: Some children who have Treacher Collins syndrome have minor deformities of the hands or fingers.

Causes 

Treacher Collins syndrome is caused by underdevelopment of a child’s facial bones, beginning before birth.

The structural problems of the face are caused by a defect in a protein called the treacle protein, which is involved in the molecular process of ribosome assembly, which is a vital step in the production of the physical structures of the body.

It is unclear why this deficiency in treacle protein specifically affects the bone structure of the face so severely. 

Genetic Mutation

The treacle defect can be caused by several different genetic mutations. A mutation is an error in a person’s DNA code that results in a problem with physical features.

The most common mutation associated with Treacher Collins syndrome is a defect in the TCOF1 gene, which is located on chromosome 5 in the 5q32 region. There are at least 100 different defects that have been known to occur on this chromosome, manifesting as Treacher Collins syndrome.

There are other genetic abnormalities that can also cause Treacher Collins syndrome, although the TCOF1 abnormality is the most common. 

The POLR1C gene, which is on chromosome 6 in the 6q21.2 region and the POLR1D gene, which is on chromosome 13 in the 13q12.2 region, both code for molecules called polymerase that help in production of ribosomes. Defects in either of these genes can cause Treacher Collins syndrome. 

Inheritance Pattern

Approximately half of the children with Treacher Collins syndrome inherit it from their parents. This is a hereditary autosomal dominant condition, which means that a person who inherits the genetic defect from one parent will develop the condition. Parents who have the condition will pass on the genetic defect to half of their children.

Every person has two chromosomes that code for treacle production, and if a person has only one defective chromosome, the body still produces some of the treacle product. However, this not is enough to support the normal formation of the bones and tissues of the face. 

Approximately half of the time, Treacher Collins syndrome develops as a de novo genetic condition, meaning that it is caused by a new mutation that was not inherited. It is believed that de novo mutations that cause Treacher Collins syndrome may develop as the result of some type of environmental factor, although no specific environmental factor has yet been identified as the cause of this condition. 

Diagnosis 

This condition, while rare, is characterized by a unique facial appearance. The diagnosis of Treacher Collins syndrome is based on the facial appearance. It can be diagnosed based on the ultrasound features prior to a child’s birth or by the baby’s physical features immediately after birth. 

X-rays are often needed to assess the exact structure of the bone deformities for surgical planning.

The condition is usually associated with genetic defects, and genetic testing of an affected child can confirm the diagnosis. Genetic testing of the parents can be helpful in assessing the risk that a couple may have more children with the disorder.

Specialized diagnostic tests are necessary to assess hearing and vision. Diagnosis of respiratory impairment may require a multidisciplinary approach, including bone X-rays, evaluation of respiratory function, or interventional diagnostic testing using a bronchoscope—a camera-equipped device that can be placed into the nose and threaded down the nasal passage to evaluate the structure of the respiratory system.

Treatment 

There is no treatment to cure Treacher Collins syndrome, but surgery can repair many of the bone deformities. Supportive care for treatment of hearing loss, visual defects, and impaired smell may improve your child’s symptoms. 

Surgery 

Children may need to have many surgeries, and the optional timing may require surgery to be spaced out over a period of several years. 

Surgical planning is based on a number of factors, including:

  • Waiting for a child to reach an age at which surgery can be well tolerated.
  • Early reconstruction of auditory bones to permit proper development of hearing function.
  • Early correction of cleft palate to avoid the associated complications.
  • Correcting cosmetic problems to maximize a child’s ability to interact with peers, while minimizing the psychological effects of social ostracism.
  • Waiting for development of facial structure to be able to plan out corrective surgery with the best long-term outcome.
  • Preventing life-threatening respiratory problems.

Because the facial deformities of Treacher Collins syndrome can be quite extensive, the surgical interventions generally do not result in a completely normal facial appearance. 

Supportive Care 

In most instances, hearing loss is treated with surgery, hearing aids, or rehabilitation. Vision may improve with surgical correction of anatomical structural abnormalities or with visual aids. 

In some instances, respiratory support with a mechanical respiratory device may be necessary. 

Coping 

There are many serious concerns that you may have if your child has Treacher Collins syndrome. 

The social and psychological issues associated with such a severe facial deformity can be excruciatingly difficult throughout the lifetime of a person who is afflicted with the condition. It can be painful for parents, siblings and other family members to watch. Psychological counseling, family counseling, and support groups may be helpful. 

Strategies that may help in the school and work setting may involve sharing details about the condition with peers through a school assembly or a workshop. Suitable approaches for interacting with peers have to be based on your individual family’s circumstances, your child, and the receptiveness of your community. 

Developing skills, such as music, art, academics, speech, theater, sports, or any other area of interest, can help build confidence, camaraderie, and acceptance.

A Word From Verywell 

Treacher Collins syndrome is among the rarest and most cosmetically unusual medical conditions. If you or your child has it, there is a very strong chance that most of the people who you meet throughout your life will never encounter another person with this condition besides you. This can be overwhelming, and the shock with which people respond to your appearance can be upsetting. 

Nevertheless, despite the extremely unique appearance of Treacher Collins syndrome, many people who are afflicted with the condition are able to cope and eventually develop strong self-esteem and resilience. 

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