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Updated 28 January 2014

Treacher Collins syndrome (TCS)

Treacher Collins syndrome (TCS), also called mandibulofacial dysostosis and Franceschetti-Zwalen-Klein syndrome, is a rare genetic disorder that causes abnormal development of facial bones and tissues, resulting in a wide range of facial defects. Symptoms vary from barely noticeable to severe. In general, most people have underdeveloped facial bones, especially cheekbones.

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BACKGROUND

Treacher Collins syndrome (TCS), also called mandibulofacial dysostosis and Franceschetti-Zwalen-Klein syndrome, is a rare genetic disorder that causes abnormal development of facial bones and tissues, resulting in a wide range of facial defects. Symptoms vary from barely noticeable to severe. In general, most people have underdeveloped facial bones, especially cheekbones.

Hearing loss is a common complication of TCS because some people have malformed ears. In very severe cases, underdeveloped facial bones may make it difficult for the patient to breathe, eat, or both.

About 40% of TCS cases are inherited, while the remaining cases occur randomly without family history of the disorder. The condition appears to affect all populations equally. Researchers estimate that TCS affects about one out of every 50,000 people worldwide.

There is no cure at present for TCS. However, most people with the disorder are able to function normally and have normal intelligence. If life-threatening complications that affect breathing do not develop, patients are generally able to live long, healthy lives. Common treatment options include hearing aids, speech-language therapy, and surgery. Some patients require reconstructive surgery in order to improve symptoms and prevent complications, such as difficulty breathing. Others may undergo reconstructive surgery to improve their facial appearance.

RISK FACTORS

A family history of Treacher Collins syndrome (TCS) increases the risk of having a child with the disorder. TCS can be passed down among family members as an autosomal dominant disorder. This means that if one parent has the disorder, there is a 50% risk that their child will have the disorder. If both parents have the disorder, there is a 75% chance that their child will have the disorder. However, more than half of the known TCS cases occur randomly without a family history of the disorder.

CAUSES

Genetic mutation: Treacher Collins syndrome (TCS) occurs when a person is born with a mutated or abnormal Treacher Collins-Franceschetti syndrome 1 (TCOF1) gene. Normally, this gene provides the body with instructions on how to produce a protein called treacle. Researchers have not discovered the exact function of treacle, but they believe that it is crucial in fetal facial development.

When the TCOF1 gene is mutated, the body does not produce enough treacle. Without enough treacle, researchers believe that the body signals the cells involved in facial bone development to self destruct, resulting in the signs and symptoms of TCS. The amount of missing treacle may be related to symptom severity.

Inheritance: About 40% of TCS cases are inherited or passed down from parents to children. Each gene has two variations, called alleles, and one allele is inherited from each parent. When TCS is inherited, the genetic mutation is passed down as an autosomal dominant trait. This means that just one copy of the mutated gene is needed for the disorder to occur. In other words, if one parent has TCS, there is a 50% chance that his or her child will have the disorder. If both parents have TCS, there is a 75% chance that the child will inherit the condition.

Random occurrence: About 60% of TCS cases occur when the TCOF1 gene randomly mutates during the development of the egg, sperm, or embryo. In such cases, there is no family history of the disorder. However, once a person has the genetic mutation, he or she can then pass on the condition to his or her children.

SIGNS AND SYMPTOMS

General: Symptoms of Treacher Collins syndrome (TCS) vary, even among family members, from barely noticeable to severe. Patients with more severe symptoms are more likely to experience complications from the disorder.

In general, individuals with TCS may have underdeveloped or absent cheekbones, an underdeveloped or smaller-than-normal jaw bone, underdeveloped or malformed ears, and small or obstructed nasal passages. They often have an unusually large mouth and a large beak-like nose. An opening in the roof of the mouth, called a cleft palate, is common. Patients may also have misaligned teeth, eyes that slant downward, sparse eyelashes, and a notch in the lower eyelids, called a coloboma.

DIAGNOSIS

Clinical evaluation: Treacher Collins syndrome (TCS) is diagnosed after a clinical evaluation. A doctor looks for the characteristic signs and symptoms of the disorder, such as ear defects, downward-slanting eyes, eyelid abnormalities, underdeveloped cheekbones, and a small lower jaw.

Imaging studies: Tests such as X-rays and magnetic resonance imaging (MRI) scans may be performed. These tests provide detailed images of the bones and internal structures and help doctors determine the severity of bone abnormalities and plan for reconstructive surgeries.

Hearing and vision tests: Hearing and vision tests may also be performed to detect hearing or vision loss.

Prenatal genetic testing: Prenatal genetic testing, such as amniocentesis and chorionic villus sampling, is possible but is not yet widely available for patients with family histories of the disorder. There are risks associated with prenatal testing, including miscarriage. Therefore, patients should talk to their doctors before making any medical decisions.

COMPLICATIONS

Breathing problems: In severe cases of Treacher Collins syndrome (TCS), underdeveloped facial structures, such as a small jaw and airway, may make breathing difficult. Breathing may be difficult at all times or just during sleep, leading to a condition called sleep apnea. Sleep apnea is a serious condition that occurs when an individual stops breathing for short periods of time during sleep. Patients with TCS may develop sleep apnea if underdeveloped facial structures block the upper airways. Because sleep apnea causes individuals to wake up frequently throughout the night, patients are often drowsy during the day.

People with severe TCS may develop life-threatening breathing problems if left untreated. Difficulty breathing may strain the cardiovascular system and increase blood pressure. In addition, patients may experience a decreased quality of life if breathing problems limit their daily activities. Patients should consult their healthcare providers if they experience feelings of sadness, low self-esteem, loss of pleasure, apathy, or difficulty with normal functioning for two weeks or longer with no known underlying cause. These may be signs of depression.

Eye infection and vision loss: If a patient with TCS has a notch in the lower eyelids, it may cause the eyes to dry out easily, increasing the risk of infection. Some people may experience vision loss as a result of eye abnormalities.

Eating difficulty: Some children with TCS may have difficulty eating because of their underdeveloped facial features, such as depressed cheekbones, a receding chin, and a cleft palate.

Hearing loss: About half of people with TCS experience hearing loss, which ranges from mild to severe, as a result of defects in the middle ear. The type of hearing loss associated with TCS is called conductive hearing loss. In most cases, hearing loss is not severe enough to be termed deafness.

Reactions to anesthesia: Patients with severe TCS have an increased risk of experiencing aspiration with general anesthesia because they have difficulty breathing. Aspiration occurs when foreign matter is inhaled into the lungs, most often when the contents of the stomach enter the lungs after vomiting. Aspiration is very serious because it can cause life-threatening infections in the lungs. Therefore, endotracheal tubes should be inserted into a patient's throat before anesthesia is administered if he or she has TCS.

Speech problems: People with TCS may have speech problems. These problems may occur as a result of underdeveloped facial structures (e.g., cleft palate), which make it difficult to properly form sounds, or as a result of hearing loss.

TREATMENT

General: There is currently no known cure for Treacher Collins syndrome (TCS). However, most people with the disorder are able to function normally as adults. A group of craniofacial specialists typically work with the patient to design an individualized treatment plan.

Common treatment options include hearing aids, speech-language therapy, and surgery. Many patients require reconstructive surgery in order to improve symptoms and prevent complications. Others may undergo reconstructive surgery to improve their facial appearance. Children who require reconstructive surgery usually undergo several surgeries between age five and adolescence.

Hearing aids: People with TCS who have hearing loss may use hearing aids. People often use conductive hearing aids such as the BAHA© bone-anchored hearing aid, because their ears are malformed and unable to hold an earmold hearing aid. These surgically implanted hearing aids help people who have missing ear canals, non-functioning middle ears, or other conditions that cannot be treated using traditional hearing aids. Unlike other types of hearing aids, they allow sound to be conducted through the bone rather than the middle ear.

Speech-language therapy: Speech-language therapy may be beneficial if a patient with TCS has speech problems from underdeveloped facial features, such as depressed cheekbones, a receding chin, and a cleft palate. During speech-language therapy, a qualified speech-language professional (SLP) works with the patient on a one-to-one basis in order to help improve speech, language, and communication skills. These programs may also help children with eating problems. Programs are tailored to the patient's individual needs and may include family education and instruction.

Speech pathologists use a variety of exercises to improve the patient's communication skills. Exercises typically start off simple and become more complex as therapy progresses. For instance, the therapist may ask the patient to name objects, tell stories, or explain the purpose of an object.

On average, patients receive five or more hours of therapy per week for three months to several years. Doctors generally recommend starting treatment early to ensure the best possible outcome for the child.

Tracheostomy: If the patient experiences difficulty breathing, surgery may be performed to create an opening in the windpipe. During the procedure, called a tracheostomy, an incision is made into the airway, and a breathing tube is inserted into the opening. The patient may continue breathing through the tube for several years, until the lower jaw has grown enough or another surgery has been performed to improve breathing. Tracheostomy tubes are replaced periodically. Although uncommon, tracheostomies may cause serious complications, including bleeding, collapsed lung, air trapped under the skin near the tracheostomy, damage to the esophagus, and laryngeal nerve damage.

Continuous positive airway pressure (CPAP): A machine called a continuous positive airway pressure (CPAP) machine is the most common and effective treatment for patients with moderate to severe sleep apnea. This machine delivers air through a mask placed over the nose during sleep. The mask does not breathe for the patient, but pushes air into the patient's mouth when he or she inhales. This air movement keeps the airways open, preventing sleep apnea and snoring. Patients who use a CPAP machine should tell their doctors if their weight changes. If the patient loses or gains weight, the pressure settings may need to be changed.

Dental devices: Patients may also wear devices over their mouths to control sleep apnea. Some devices bring the jaw forward in order to open the throat and control symptoms of mild obstructive sleep apnea. Patients should talk to their dentist to determine the best oral appliance for them. Patients should visit their dentist every six months for the first year after they find an oral appliance that works for them. After the first year, patients should visit their dentist and healthcare provider annually to make sure that the device is effectively relieving the symptoms of sleep apnea.

Surgery: Reconstructive surgery is available to treat symptoms or complications and to improve physical appearance. The exact type of surgery performed depends on each patient's individual abnormalities. Different surgeries are performed at different ages, depending on the child's stage of development. Children who require reconstructive surgery usually undergo several surgeries between age five and adolescence.

For instance, the first surgery is often done to correct the eyelid coloboma in the first years of life. Surgery to correct depressed cheekbones is usually performed before the child is five years old, and the ears are usually reconstructed when the child is about six years old. Surgery to lengthen the lower jaw may begin when the child is in elementary school and may be completed when the child is in late adolescence or early adulthood. Moderate to severe sleep apnea may need to be treated with surgery. During this surgery the extra tissue from the throat or nose that is blocking the airway is removed.

INTEGRATIVE THERAPIES

Currently there is a lack of available scientific evidence on the use of integrative therapies for the treatment or prevention of Treacher Collins syndrome (TCS).

PREVENTION

Because some cases of Treacher Collins syndrome (TCS) occur randomly with no family history of the disorder, there is no known way to prevent it. Early diagnosis and prompt treatment is important in order to prevent serious complications, such as difficulty breathing.

Prenatal genetic testing, such as amniocentesis and chorionic villus sampling, is possible, but not yet widely available for patients with family histories of the disorder. Because TCS can be detected in a fetus, parents may choose whether to continue the pregnancy. There are risks associated with prenatal testing, including miscarriage. Therefore, patients should talk to their doctor before making any medical decisions. Patients with TCS can meet with a genetic counselor to learn about the risks of having children with TCS.

AUTHOR INFORMATION

This information has been edited and peer-reviewed by contributors to the Natural Standard Research Collaboration (www.naturalstandard.com).

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Copyright © 2011 Natural Standard (www.naturalstandard.com)
 
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